  1 A most minute and exact description of the newly hatched larva of Chionobas AËllo is given by the American entomologist, Samuel H. Scudder. Ann. Soc. Ent. de Belgique, xvi., 1873. 2 I am aware that this certainly cannot be said of philosophers like Lotze or Herbert Spencer; but these are at the same time both naturalists and philosophers. 3 “Über die Artrechte des Polyommatus Amyntas und Polysperchon.” Stett. ent. Zeit. 1849. Vol. x. p. 177–182. [In Kirby’s “Synonymic Catalogue of Diurnal Lepidoptera” Plebeius Amyntas is given as a synonym and P. Polysperchon as a var. of P. Argiades Pall. R.M.] 4 “Die Arten der Lepidopteren-Gattung Ino Leach, nebst einigen Vorbemerkungen Über LocalvarietÄten.” Stett. ent. Zeit. 1862. Vol. xxiii. p. 342. 5 [Eng. ed. W.H. Edwards has since pointed out several beautiful cases of seasonal dimorphism in America. Thus Plebeius Pseudargiolus is the summer form of P. Violacea, and Phyciodes Tharos the summer form of P. Marcia. See Edwards’ “Butterflies of North America,” 1868–79.] 6 [Eng. ed. I learn by a written communication from Dr. Speyer that two GeometrÆ, Selenia Tetralunaria and S. Illunaria HÜb., are seasonally dimorphic. In both species the winter form is much larger and darker.] [Selenia Lunaria, S. Illustraria, and some species of Ephyra (E. Punctaria and E. Omicronaria) are likewise seasonally dimorphic. For remarks on the case of S. Illustraria see Dr. Knaggs in Ent. Mo. Mag., vol. iii. p. 238, and p. 256. Some observations on E. Punctaria were communicated to the Entomological Society of London by Professor Westwood in 1877, on the authority of Mr. B.G. Cole. See Proc. Ent. Soc. 1877, pp. vi, vii. R.M.] 7 [In 1860 Andrew Murray directed attention to the disguising colours of species which, like the Alpine hare, stoat, and ptarmigan, undergo seasonal variation of colour. See a paper “On the Disguises of Nature, being an inquiry into the laws which regulate external form and colour in plants and animals.” Edinb. New Phil. Journ., Jan. 1860. In 1873 I attempted to show that these and other cases of “variable protective colouring” could be fairly attributed to natural selection. See Proc. Zoo. Soc., Feb. 4th, 1873, pp. 153–162. R.M.] 8 [A phenomenon somewhat analogous to seasonal change of protecting colour does occur in some Lepidoptera, only the change, instead of occurring in the same individual, is displayed by the successive individuals of the same brood. See Dr. Wallace on Bombyx Cynthia, Trans. Ent. Soc. Vol. v. p. 485. R.M.] 9 “Über den Einfluss der Isolirung auf die Artbildung.” Leipzig, 1872, pp. 55–62. 10 [Mr. A.R. Wallace maintains that the obscurely coloured females of those butterflies which possess brightly coloured males have been rendered inconspicuous by natural selection, owing to the greater need of protection by the former sex. See “Contributions to the Theory of Natural Selection,” London, 1870, pp. 112–114. It is now generally admitted that the underside of butterflies has undergone protectional adaptation; and many cases of local variation in the colour of the underside of the wings, in accordance with the nature of the soil, &c., are known. See, for instance, Mr. D. G. Rutherford on the colour-varieties of Aterica Meleagris (Proc. Ent. Soc. 1878, p. xlii.), and Mr. J. Jenner Weir on a similar phenomenon in Hipparchia Semele (loc. cit. p. xlix.) R.M.] 11 [The fact that moths which, like the GeometrÆ, rest by day with the wings spread out, are protectively marked on the upper side, fully corroborates this statement. R.M.] 12 “Über die Einwirkung verschiedener, wÄhrend der Entwicklungsperioden angewendeter WÄrmegrade auf die FÄrbung und Zeichnung der Schmetterlinge.” A communication to the Society of Natural Science of Steiermark, 1864. 13 See Exp. 9, Appendix I. 14 See Exp. 11, Appendix I. 15 See Exps. 4, 9, and 11, Appendix I. 16 It seems to me very necessary to have a word expressing whether a species produces one, two, or more generations in the year, and I have therefore coined the expression mono-, di-, and polygoneutic from ???e??, I produce. 17 [Eng. ed. In the German edition, which appeared in 1874, I was not able to support this hypothesis by geographical data, and could then only ask the question “whether in the most northern portion of its area of distribution, appears in two or only in one generation?” This question is now answered by the Swedish Expedition to the Yenisei in 1876. Herr Philipp Trybom, one of the members of this expedition, observed A. Levana at the end of June and beginning of July, in the middle of Yenisei, in 60°-63° N. (DagfjÄrilar frÅn Yenisei in Översigt ap k. Vertensk. Akad. FÖrhandlingon, 1877, No. 6.) Trybom found Levana at Yenisk on June 23rd, at Worogova (61° 5´) on July 3rd, at Asinova (61° 25´) on July 4th, at Insarowa (62° 5´) on July 7th, and at Alinskaja (63° 25´) on July 9th. The butterflies were especially abundant at the beginning of June, and were all of the typical Levana form. Trybom expressly states, “we did not find a single specimen which differed perceptibly from Weismann’s Figs. 1 and 2 (‘Saison-Dimorphismus’ Taf. I.).” The Swedish expedition soon left the Yenisei, and consequently was not able to decide by observations whether a second generation possessing the Prorsa form appeared later in the summer. Nevertheless, it may be stated with great probability that this is not the case. The districts in which Levana occurs on the Yenisei have about the same isotherm as Archangel or Haparanda, and therefore the same summer temperature. Dr. Staudinger, whose views I solicited, writes to me:—“In Finnmark (about 67° N.) I observed no species with two generations; even Polyommatus PhlÆas, which occurs there, and which in Germany has always two, and in the south, perhaps, three generations, in Finnmark has only one generation. A second generation would be impossible, and this would also be the case with Levana in the middle of Yenisei. I certainly have Levana and Prorsa from the middle of Amur, but Levana flies there at the end of May, and the summers are very warm.” The middle of Amur lies, moreover, in 50° N. lat., and therefore 10°-13° south of the districts of the Yenisei mentioned. It must thus be certainly admitted that on the Yenisei A. Levana occurs only in the Levana form, and that consequently this species is at the present time, in the northernmost portion of its area of distribution, in the same condition as that in which I conceive it to have been in mid Europe during the glacial period. It would be of the greatest interest to make experiments in breeding with this single-brooded Levana from the Yenisei, i.e., to attempt to change its offspring into the Prorsa form by the action of a high temperature. If this could not be accomplished it would furnish a confirmation of my hypothesis than which nothing more rigorous could be desired.] 18 See Exp. 10, Appendix I. 19 When Dorfmeister remarks that hibernating pupÆ which, at an early stage “were taken for development into a room, or not exposed to any cold, gave dwarfed, weakly and crippled,” or otherwise damaged butterflies, this is entirely attributable to the fact that this able entomologist had neglected to supply the necessary moisture to the warm air. By keeping pupÆ over water I have always obtained very fine butterflies. 20 [For other remarkable cases of sexual dimorphism (not antigeny in the sense used by Mr. S.H. Scudder, Proc. Amer. Acad., vol. xii. 1877, pp. 150–158) see Wallace “On the Phenomena of Variation and Geographical Distribution, as illustrated by the PapilionidÆ of the Malayan Region,” Trans. Linn. Soc., vol. xxv. 1865, pp. 5–10. R.M.] 21 [Eng. ed. Dimorphism of this kind has since been made known: the North American Limenitis Artemis and L. Proserpina are not two species, as was formerly believed, but only one. Edwards bred both forms from eggs of Proserpina. Both are single-brooded, and both have males and females. The two forms fly together, but L. Artemis is much more widely distributed, and more abundant than L. Proserpina. See “Butterflies of North America,” vol. ii.] 22 [Eng. ed. Edwards has since proved experimentally that by the application of ice a large proportion of the pupÆ do indeed give rise to the var. Telamonides. He bred from eggs of Telamonides 122 pupÆ, which, under natural conditions, would nearly all have given the var. Marcellus. After two months’ exposure to the low temperature there emerged from August 24th to October 16th, fifty butterflies, viz. twenty-two Telamonides, one intermediate form between Telamonides and Walshii, eight intermediate forms between Telamonides and Marcellus more nearly related to the former, six intermediate forms between Telamonides and Marcellus, but more closely resembling the latter, and thirteen Marcellus. Through various mishaps the action of the ice was not complete and equal. See the “Canadian Entomologist,” 1875, p. 228. In the newly discovered case of Phyciodes Tharos also, Edwards has succeeded in causing the brood from the winter form to revert, by the application of ice to this same form. See Appendix II. for a rÉsumÉ of Edwards’ experiments upon both Papilio Ajax and Phyciodes Tharos. R.M.] 23 Thus from eggs of Walshii, laid on April 10th, Edwards obtained, after a pupal period of fourteen days, from the 1st to the 6th of June, fifty-eight butterflies of the form Marcellus, one of Walshii, and one of Telamonides. 24 [The word ‘Amixie,’ from the Greek ????a, was first adopted by the author to express the idea of the prevention of crossing by isolation in his essay “Über den Einfluss der Isolirung auf die Artbildung,” Leipzig, 1872, p. 49. R.M.] 25 [Eng. ed. In 1844, Boisduval maintained this relationship of the two forms. See Speyer’s “Geographische Verbreit. d. Schmetterl.,” i. p. 455.] 26 According to a written communication from Dr. Staudinger, the female BryoniÆ from Lapland are never so dusky as is commonly the case in the Alps, but they often have, on the other hand, a yellow instead of a white ground-colour. In the Alps, yellow specimens are not uncommon, and in the Jura are even the rule. 27 [According to W.F. Kirby (Syn. Cat. Diurn. Lepidop.), the species is almost cosmopolitan, occurring, as well as throughout Europe, in Northern India (var. Timeus), Shanghai (var. Chinensis), Abyssinia (var. PseudophlÆas), Massachusetts (var. Americana), and California (var. HypophlÆas). In a long series from Northern India, in my own collection, all the specimens are extremely dark, the males being almost black. R.M.] 28 [Eng. ed. From a written communication from Dr. Speyer, it appears that also in Germany there is a small difference between the two generations. The German summer brood has likewise more black on the upper side, although seldom so much as the South European summer brood.] 29 [Assuming that in all butterflies similar colours are produced by the same chemical compounds. R.M.] 30 [Mr. H.W. Bates mentions instances of local variation in colour affecting many distinct species in the same district in his memoir “On the Lepidoptera of the Amazon Valley;” Trans. Linn. Soc., vol. xxiii. Mr. A.R. Wallace also has brought together a large number of cases of variation in colour according to distribution, in his address to the biological section of the British Association at Glasgow in 1876. See “Brit. Assoc. Report,” 1876, pp. 100–110. For observations on the change of colour in British Lepidoptera according to distribution see papers by Mr. E. Birchall in “Ent. Mo. Mag.,” Nov., 1876, and by Dr. F. Buchanan White, “Ent. Mo. Mag.,” Dec., 1876. The colour variations in all these cases are of course not protective as in the well-known case of Gnophos obscurata, &c. R.M.] 32 “On the Origin and Metamorphoses of Insects,” London, 1874. 33 I at first thought of designating the two forms of cyclical or homochronic heredity as ontogenetic- and phyletic-cyclical heredity. The former would certainly be correct; the latter would be also applicable to alternation of generation (in which actually two or more phyletic stages alternate with each other) but not to all those cases which I attribute to heterogenesis, in which, as with seasonal dimorphism, a series of generations of the same phyletic stage constitute the point of departure. 34 When Meyer-DÜrr, who is otherwise very accurate, states in his “Verzeichniss der Schmetterlinge der Schweiz,” (1852, p. 207), that the winter and summer generations of P. Ægeria differ to a small extent in the contour of the wings and in marking, he has committed an error. The characters which this author attributes to the summer form are much more applicable to the female sex. There exists in this species a trifling sexual dimorphism, but no seasonal dimorphism. 35 P.C. Zeller, “Bemerkungen Über die auf einer Reise nach Italien und Sicilien gesammelten Schmetterlingsarten.” Isis, 1847, ii.-xii. 36 “Isoporien der europÄischen Tagfalter.” Stuttgart, 1873. 37 [Trans. Linn. Soc., vol. xxv. 1865, p. 9. R.M.] 38 It is certainly preferable to make use of the expression “metagenesis” in this special sense instead of introducing a new one. As a general designation, comprehending metagenesis and heterogenesis, there will then remain the expression “alternation of generation,” if one does not prefer to say “cyclical propagation.” The latter may be well used in contradistinction to “metamorphosis.” 39 Loc. cit. chap. iv. 40 The idea that alternation of generation is derived from polymorphism (not the reverse, as usually happens; i.e. polymorphism from alternation of generation) is not new, as I find whilst correcting the final proof. Semper has already expressed it at the conclusion of his interesting memoir, “Über Generationswechsel bei Steinkorallen,” &c. See “Zeitschrift f. wiss. Zool.” vol. xxii. 1872. 41 See my essay “Über den Einfluss der Isolirung auf die Artbildung.” Leipzig, 1872. 42 [In the case of monogoneutic species which, by artificial ‘forcing,’ have been made to give two generations in the year, it has generally been found that the reproductive system has been imperfectly developed in the second brood. A minute anatomical investigation of the sexual organs in the two broods of seasonally dimorphic insects would be of great interest, and might lead to important results. R.M.] 43 “GrundzÜge der Zoologie.” 2nd ed. Leipzig, 1872. Introduction. 44 With reference to this subject, see the discussion by the Belgian Entomological Society, Brussels, 1873. 45 P.E. MÜller, “Bidrag til Cladocerners Fortplantingshistorie,” 1868. 46 Sars, in “FÖrhandlinger i Videnskabs Selskabet i Christiania,” 1873, part i. 47 [Eng. ed. Recent researches on alternation of generation in the Daphniacea have convinced me that direct action of external conditions does not in these cases come into consideration, but only indirect action.] 48 See my memoir, “Über Bau und Lebenserscheinungen der Leptodora hyalina,” Zeitschrift f. wiss. Zool., vol. xxiv. part 3, 1874. 49 Stettin. entom. Zeit., vol. xviii. p. 83, 1857. 50 Compt. Rend., vol. lxxvii. p. 1164, 1873. 51 [“Accidental” in the sense of our being in ignorance of the laws of variation, as so frequently insisted upon by Darwin. R.M.] 52 [Eng. ed. Since this was written I have studied the ornamental colours of the DaphniidÆ; and, as a result, I no longer doubt that sexual selection plays a very important part in the marking and colouring of butterflies. I by no means exclude both transforming factors, however; it is quite conceivable, on the contrary, that a change produced directly by climate may be still further increased by sexual selection. The above given case of Polyommatus PhlÆas may perhaps be explained in this manner. That sexual selection plays a part in butterflies, is proved above all by the odoriferous scales and tufts of the males discovered by Fritz MÜller.] [For remarks on the odours emitted by butterflies and moths, see Fritz MÜller in “Jena. Zeit. f. Naturwissen.,” vol. xi. p. 99; also “Notes on Brazilian Entomology,” Trans. Ent. Soc. 1878, p. 211. The odoriferous organs of the female HeliconinÆ are fully described in a paper in “Zeit. f. Wissen. Zool.,” vol. xxx. p. 167. The position of the scent-tufts in the sphinx-moths is shown in Proc. Entom. Soc. 1878, p. ii. Many British moths, such as Phlogophora meticulosa, Cosmia trapezina, &c. &c., have tufts in a similar position. The fans on the feet of Acidalia bisetata, Herminia barbalis, H. tarsipennalis, &c., are also probably scent organs. A large moth from Jamaica, well known to possess a powerful odour when alive (Erebus odorus Linn.), has great scent-tufts on the hind legs. For the application of the theory of sexual selection to butterflies, see, in addition, to Darwin’s “Descent of Man,” Fritz MÜller in “Kosmos,” vol. ii. p. 42; also for January, 1879, p. 285; and Darwin in “Nature,” vol. xxi. January 8th, 1880, p. 237. R.M.] 53 NÄgeli, “Entstehung und Begriff der naturhistorischen Art,” Munich, 1865, p. 25. The author interprets the facts above quoted in a quite opposite sense, but this is obviously erroneous. 54 See my essay, “Über den Einfluss der Isolirung auf die Artbildung.” Leipzig, 1872. 55 [Eng. ed. In the summer of 1877, Dr. Hilgendorf again investigated the Steinheim fossil shells, and found his former statements to be completely confirmed. At the meeting of the German Naturalists and Physicists at Munich, in 1877, he exhibited numerous preparations, which left no doubt that the chief results of his first research were correct, and that there have been deposited a series of successively derived species together with their connecting intermediate forms.] 56 See my essay, “Über die Berechtigung der Darwin’schen Theorie.” Leipzig, 1868. 57 I expressly insist upon this here, because the notice of Askenasy’s thoughtful essay which I gave in the “Archiv fÜr Anthropologie” (1873) has frequently been misunderstood. 58 The experiments upon Papilio Ajax and Phyciodes Tharos, described in this Appendix, were made by Mr. W.H. Edwards (see his “Butterflies of North America;” also the “Canadian Entomologist,” vol. vii. p. 228–240, and vol. ix. p. 1–10, 51–5, and 203–6); and I have added them, together with some hitherto unpublished results, to Dr. Weismann’s Essay, in order to complete the history of the subject of seasonal dimorphism up to the present time.—R.M. 59 This is a striking illustration of the diversity of individual constitution so frequently insisted on by Dr. Weismann in the foregoing portion of this work. 60 The reader who wishes to acquire a detailed knowledge of the different varieties of this butterfly, of which a very large number are known, must consult the plates and descriptions in Edwards’ “Butterflies of North America,” vol. ii. 61 Mr. Edwards has shown also that Argynnis Myrina can lay fertile eggs when but a few hours out of the chrysalis. Canad. Ent., September, 1876, vol. viii. No. 9. 62 Mr. Edwards remarks that the habit of becoming lethargic is of great service to a digoneutic species in a mountain region where it is exposed to sharp changes of temperature. “If the fate of the species depended on the last larval brood of the year, and especially if the larvÆ must reach a certain stage of growth before they were fitted to enter upon their hibernation, it might well happen that now and then an early frost or a tempestuous season would destroy all the larvÆ of the district.” 64 See Canad. Ent., vol. ix. p. 69. 65 Figures of the different forms of this species are given in vol. i. of Edward’s “Butterflies of North America.” 66 Only the species of Smerinthus can be made to lay eggs regularly in confinement; Macroglossa Stellatarum laid a number in a large gauze-covered breeding-cage; the species of Deilephila could not be induced to lay more than single ones in such a cage. From species of ChÆrocampa also I never obtained but a few eggs, and from Sphinx and Acherontia never more than single ones. 67 [Eng. ed. Since the appearance of the German edition of this work, numerous descriptions of the young stages of caterpillars have been given, but in all cases without representing the relationship of the forms.] [In the excellent figures of larvÆ at various stages of growth, given in some of the more recent works on Lepidoptera, there will be found much material which may be regarded as a contribution to the field of research entered on by the author in the present essay, i.e. the ontogeny and comparative morphology of larval markings, although it is much to be regretted that the figures and descriptions have not been given from this point of view. In his “Butterflies of North America,” for example, W.H. Edwards figures the young as well as the adult larvÆ of species of Apatura, Argynnis, Libythea, Phyciodes, Limenitis, Colias, Papilio, &c. Burmeister, in his recently published “LÉpidoptÈres de la RÉpublique Argentine,” figures the young stages of species of Caligo, Opsiphanes, Callidryas, Philampelus, &c. Messrs. Hellins and Buckler have figured and described the early stages of large numbers of the caterpillars of British Lepidoptera, but their figures remain unpublished. The larvÆ of many of our native species belonging to the genera Liparis, TÆniocampa, Epunda, Cymatophora, Calocampa, &c., are dull when young, but become brightly coloured at the last moult. Such changes of colour are probably associated with some change, either in the habits or in the environment; and a careful study of the ontogenetic development of such species in connection with their life-history would furnish results of great value to the present inquiry. The same remarks apply to those NoctuÆ larvÆ which are brightly coloured in their young stages, and become dull when adult. Among other papers which may be considered as contributions to the present subject, I may mention the following:—In 1864 Capt. Hutton published a paper, “On the Reversion and Restoration of the Silkworm, Part II.” (Trans. Ent. Soc. 1864, p. 295), in which he describes the various stages of development of several species of BombycidÆ. In 1867 G. Semper published accounts of the early stages of several Sphinx-larvÆ (“BeitrÄge zur Entwicklungsgeschichte einiger ostasiatischer Schmetterlinge,” Verhandl. k.k. Zoolog.-botan. Gesell. in Wien, vol. xvii.). The question as to the number of claspers in young NoctuÆ larvÆ has been raised in notes by Dr. F. Buchanan White (“Ent. Mo. Mag.,” vol. v. p. 204) and B. Lockyer (“Entomologist,” 1871, p. 433). A valuable paper, “On the Embryonic LarvÆ of Butterflies,” was published in 1871 by S.H. Scudder (“Ent. Mo. Mag.,” vol. viii. p. 122). For remarks on the development of the larva of Papilio Merope, see J.P. Mansel Weale in Trans. Ent. Soc., 1874, p. 131, and Pl. I.; also this author on the young stages of the larva of Gynanisa Isis, Trans. Ent. Soc., 1878, p. 184. For an account of the development of the larvÆ of certain North American species of Satyrus, see W.H. Edwards in the “Canadian Entom.,” vol. xii. p. 21. Mr. P.H. Gosse’s recent description of the newly hatched caterpillar of Papilio Homerus (Proc. Ent. Soc. 1879, p. lv), furnishes a good illustration of the value of studying the ontogeny. The natural affinities of the PapilionidÆ were at one time much disputed, some systematists placing this family at the head of the Lepidoptera, and others regarding them as being more closely allied to the moths. Mr. Gosse’s observation tends to confirm the latter view, now generally received by Lepidopterists, since he states that the larva in question “suggests one of the great SaturniadÆ, such as Samia Cecropia.” Mr. Scudder, in the paper above referred to, adopts an analogous argument to show the close relationship between the PapilionidÆ and HesperidÆ. R.M.] 68 [Mr. A.G. Butler has recently furnished a good illustration of the danger of classifying Lepidoptera according to the affinities of the perfect insects only, in his paper, “On the Natural Affinities of the Lepidoptera hitherto referred to the Genus Acronycta of authors,” Trans. Ent. Soc. 1879, p. 313. If the author’s views are ultimately accepted, the species at present grouped under this genus will be distributed among the ArctiidÆ, LiparidÆ, NotodontidÆ, and NoctuÆ. Mr. Butler’s determination of the affinities of the species supposed to belong to the genus mentioned, is based chiefly upon a comparative examination of the larvÆ, and this is far more likely to show the true blood-relationship of the species than a comparison of the perfect insects only. A study of the comparative ontogeny can alone give a final answer to this question. R.M.] 69 [In his recent revision of the SphingidÆ, Mr. A.G. Butler (Trans. Zoo. Soc., vol. ix. part x.) retains Walker’s arrangement. R.M.] 70 The deposition of black pigment may commence immediately before ecdysis. 71 [Mr. Herbert Goss states (Proc. Ent. Soc. 1878, p. v.) that according to his experience, the green and brown varieties of C. Porcellus (erroneously printed as Elpenor in the passage referred to) are about equally common, the former colour not being in any way confined to young larvÆ. Mr. Owen Wilson in his recent work, “The LarvÆ of British Lepidoptera and their food-plants,” figures (Pl. VIII., Figs. 3 and 3a) the two forms, both apparently in the adult state. During the years 1878–79, my friend, Mr. J. Evershed, jun., took five of these full-grown larvÆ in Surrey, one of these being the green variety. In order to get more statistics on this subject, I applied this year (1880) to Messrs. Davis of Dartford, who informed me that among 18–20 adult caterpillars of Porcellus in their possession, there was only one green specimen. R.M.] 72 I unite the genera Pergesa and Darapsa of Walk. with ChÆrocampa, Dup.; the first appears to me to be quite untenable, since it is impossible that two species, of which the caterpillars agree so completely as those of C. Elpenor and Porcellus, can be located in different genera. Porcellus indeed was referred to the genus Pergesa because of its different contour of wings, an instance which distinctly shows how dangerous it is to attempt to found Lepidopterous genera without considering the caterpillars. The genus Darapsa also appears to me to be of very doubtful value, and in any case requires further confirmation with respect to the larval forms. 73 [Mr. A.G. Butler (Trans. Zoo. Soc., vol. ix., part. x., 1876) gives a list of about eighty-four species of ChÆrocampa, and sixteen of Pergesa, besides numerous other species belonging to several genera placed between ChÆrocampa and Pergesa. Of Darapsa, he states “that this genus was founded upon most heterogeneous material, the first three species being referable to HÜbner’s genus Otus, the fifth to Walker’s genus Diodosida, the sixth and eighth to the genus Daphnis of HÜbner, the seventh, ninth, and tenth to ChÆrocampa of Duponchel; there therefore remains only the fourth species, allied to ChÆrocampa, but apparently sufficiently distinct.” The species still retained in the genus Darapsa is D. rhodocera, Wlk., from Haiti. R.M.] 74 [Otus Syriacus of Butler’s revision. R.M.] 75 Abbot and Smith. “The Natural History of the rarer Lepidopterous Insects of Georgia, collected from the observations of John Abbot, with the plants on which they feed.” London, 1797, 2 vols. fol. 76 [Otus Choerilus and O. Myron of Butler’s revision. R.M.] 77 [To this group may also be added Ampelophaga Rubiginosa, MÉnÉtriÉs, from China and Japan, the caterpillar of which, having the distinct subdorsal line without any trace of eye-spots, is figured by Butler (loc. cit., Pl. XCI., Fig. 4). This author also gives a figure of another species belonging to the subfamily ChÆrocampinÆ (Pl. XC., Fig. 11), viz. Acosmeryx Anceus, Cram., from Amboina, Java, Silhet, and S. India; the caterpillar is green, with seven oblique yellow stripes along the sides, and a very conspicuous white subdorsal line with a red border above. As there are no eye-spots, this species may be referred to the present group provisionally, although its general marking is very distinct from that of the ChÆrocampa group. R.M.] 78 [Eng. ed. Dr. Staudinger has since obtained the caterpillar of C. Alecto from Beyrout; it possesses “a very distinct subdorsal line, and on the fourth segment a beautiful eye-spot, which is repeated with gradual diminution to segments 7–8”.] 79 Figured in “A Catalogue of Lepidopterous Insects in the Museum of the East India Company,” by Thomas Horsfield and Frederick Moore. London, 1857. Vol. i., Pl. XI. 80 Figured in Trans. Ent. Soc., New Series, vol. iv., Pl. XIII. 81 Ibid. 82 [The following species figured by Butler (loc. cit. Pls. XC. and XCI.) appear to belong to the second group—ChÆrocampa Japonica, Boisd., which is figured in two forms, one brown, and the other green. The former has two distinct ocelli on the fourth and fifth segments, and a distinct rudiment on the sixth, whilst the subdorsal line extends from the second eye-spot to the caudal horn, and beneath this line the oblique lateral stripes stand out conspicuously in dark brown on a lighter ground. The ocelli are equally well developed on the fourth and fifth segments in the green variety, the subdorsal line commencing on the sixth segment, and extending to the caudal horn; there is no trace of a third eye-spot, nor are there any oblique lateral stripes; the insect is almost the exact counterpart of C. Elpenor in its fourth stage. (See Fig. 21, Pl. IV.) Pergesa Mongoliana, Butl., is brown, without a trace of the subdorsal line except on the three front segments, and with only one large eye-spot on the fourth segment. ChÆrocampa Lewisii, Butl., from Japan, is likewise figured in two forms. The brown variety has the subdorsal line on the three front segments only, distinct ocelli on the fourth and fifth segments, and gradually diminishing rudiments on the remaining segments. The green form appears to be transitional between the present and the third group, as it possesses a distinct, but rudimentary eye-spot on the third segment, besides the fully developed ones on the fourth and fifth, and very conspicuous, but gradually decreasing repetitions of rudimentary ocelli on segments 6–10. To this group may be added ChÆrocampa Aristor, Boisd., the caterpillar of which is figured by Burmeister (LÉp. RÉp. Arg., Pl. XV., Fig. 4) in the characteristic attitude of alarm, with the front segments retracted, and the ocelli on the fourth segment prominently exposed. The subdorsal line is present in this species. Burmeister also figures two of the early stages (Pl. XV., Fig. 7, A and B), and describes the complete development of Philampelus LabruscÆ, another species belonging to the subfamily ChÆrocampinÆ. The earliest stage (3–4 days old) is simple green, with no trace of any marking except a black spot on each side of the fourth segment, the position of the future ocelli. A curved horn is present both in this stage and the following one, during which the caterpillar is still green, but now has seven oblique red lateral stripes. The caudal horn is shed at the second moult, after which the colour becomes darker, the adult larva (figured by Madame MÉrian, in her work on Surinam, pl. 34 and Sepp., pl. 32) being mottled brown. In addition to the ocellus on the fourth segment, there is another slightly larger on the eleventh segment, so that this species may perhaps be another transition to the third group; but our knowledge is still too imperfect to attempt to generalize with safety. R.M.] 83 Cat. Lep. Ins. East Ind. Comp., Pl. XIII. [Figured also by Butler (=ChÆerocampa Silhetensis, Walker), loc. cit. Pl. XCII., Fig. 8. R.M.] 84 Cat. Lep. Ins. East Ind. Comp., Pl. XIII. [Figured also by Butler, loc. cit. Pl. XCI., Fig. 1. R.M.] 85 Horsfield and Moore, loc. cit. Pl. X. 86 Ibid. [=Pergesa Acteus, Walker. R.M.] 87 [Figured also by Burmeister, loc. cit. Pl. XV., Fig. 3. R.M.] 88 Horsfield and Moore, loc. cit., Pl. XI. 89 To be accurate this should be designated the infra-spiracular line; but this term cannot be well applied except in cases where there is also a supra-spiracular line, as, for instance, in Anceryx (Hyloicus) Pinastri. 90 Upon this fact obviously depends the statement of that extremely accurate observer RÖsel, that the caterpillar of EuphorbiÆ is but very slightly variable (“Insektenbelustigungen,” Bd. iii. p. 36). I formerly held the same opinion, till I convinced myself that this species is very constant in some localities, but very variable in others. It appears that local influences make the caterpillar variable. 92 “Die Pflanzen und Raupen Deutschlands.” Berlin, 1860, p. 83. 94 The fading of the red anteriorly has not been represented in the figure. 95 [The caterpillar of Deilephila Euphorbiarum, figured by Burmeister (LÉp. RÉp. Arg., Pl. XVI, Fig. 1) belongs to this stage. R.M.] 96 [In concluding this account of the ChÆrocampinÆ I may call attention to the following species, which have since been figured by Burmeister:—Pachylia Ficus, Linn. (loc. cit. Pl. XIV., Figs. 1 and 2); during the three first stages the larva is uniformly green, with a yellow subdorsal line, and below this ten oblique yellow stripes slanting away from the head; after the third moult the colour completely changes, the whole area of the body being divided into two distinct portions by the subdorsal line, above which the colour is red, and underneath of a pale green; the oblique stripes have almost disappeared; no occelli nor annuli are present. Pachylia Syces, HÜbn. (loc. cit. Fig. 3); very similar to the last species in its young stages (figured also by MÉrian, Surin. pl. 33). Philampelus Vitis, Linn. (loc. cit. Figs. 4 and 5); two stages represented; between first and second moults green, with oblique paler stripes slanting in same direction as in Pachylia, and each one containing a red streak surrounding the spiracle. When adult, the ground-colour is yellow above and green beneath, the whole surface being mottled with deep black and red transverse markings; the oblique stripes whitish, bordered with black at their lower extremities (figured also by MÉrian, pls. 9 and 39). Philampelus Anchemolus, Cram. (loc. cit. Pl. XV., Fig. 1; MÉrian, pl. 47); green when young, with seven oblique red stripes; when adult, uniformly brown, with seven pale yellow lateral markings, the first four of which are spots, and the remainder broad oblique stripes slanting forwards. Philampelus LabruscÆ, (see note 82, p. 195). R.M.] 97 [Mimas TiliÆ of Butler’s revision. The author states that this genus is “easily distinguished from LaothoË by the form of the wings, the outer margin of secondaries deeply excavated below the apex, and the secondaries narrow and not denticulated.” Here again we have a clashing of the results arrived at by a study of the ontogeny of the larvÆ, on the one hand, and the founding of genera on the characters of the imagines only, on the other. Of the three species discussed by Dr. Weismann, Mr. Butler, following other authors, refers TiliÆ to the genus Mimas, Populi to LaothoË, and Ocellatus to Smerinthus. It is to be hoped that when our knowledge of the developmental history of larvÆ is more complete in all groups, a reconciliation between the results of the biological investigator and the pure systematist will be brought about, so that a genus may not, as at present, have such very different values when regarded from these two points of view. R.M.] 98 The caterpillar is thus figured by RÖsel. 99 [In 1879 Mr. E. Boscher found about thirty full-grown caterpillars of this species in the neighbourhood of Twickenham, ten to twelve of which were feeding on Salix viminalis, and the remainder, from a locality not far distant, on Salix triandra. The whole of the specimens taken on the plant first named, had the red-brown spots above and below the oblique stripes more or less completely developed, as I myself had an opportunity of observing. In these spotted specimens the ground-colour was bright yellowish-green, and in the others this colour was dull whitish-green above, passing into bluish-green below. Should these observations receive wider confirmation, it would be fair to conclude that this species is now in two states of phyletic development, the more advanced stage being represented by the brighter spotted variety. (See also Proc. Ent. Soc. 1879, p. xliv.). Mr. Peter Cameron has recently suggested (Trans. Ent. Soc. 1880, p. 69) that the reddish-brown spots on the Smerinthus caterpillars may serve for purposes of disguise, as they closely resemble, both in colour and form, certain galls (Phytoptus) of the food-plants of these species. If this view be admitted, these spots must be considered as a new character, now being developed by natural selection. The variation in the ground-colour of the two forms of S. Ocellatus may possibly be phytophagic, but this can only be decisively settled by a series of carefully conducted experiments. R.M.] 100 “Insekten-Belustigungen,” Suppl. Pl. 38, Fig. 40. 101 “Catalogue of Lepidop.” British Museum. [Butler divides the subfamily SmerinthinÆ into 17 genera, containing 79 species, viz. Metamimas, 2; Mimas, 4; Polyptychus, 7; Lophostethus, 1; SphingonÆpiopsis, 1; Langia, 2; Triptogon, 23; LaothoË, 2; Cressonia, 3; Paonias, 2; Calasymbolus, 5; Smerinthus, 5; Pseudosmerinthus, 2; Daphnusa, 4; Leucophlebia, 5; Basiana, 10; CÆquosa, 1. R.M.] 102 “Cabinet Orient. Entom.,” p. 13, Pl. VI., Fig. 2. [Butler places this species doubtfully among the SphinginÆ. R.M.] 104 [The larvÆ of four other species of this subfamily have since been made known through Mr. Butler’s figures. Smerinthus Tatarinovii, MÉnetriÉs (loc. cit. Pl. XC., Fig. 16), from Japan, is “pale sea-green, tuberculated with white, with seven lateral, oblique, crimson-edged white stripes.” There is no trace of the subdorsal line shown in the figure, so that this species thus appears to be in the third phyletic stage of development. Smerinthus Planus, Walker, from China (loc. cit. Pl XCII., Fig. 11), is “pale green, with white or yellow lateral stripes.” A trace of the subdorsal line remains on the front segments, thus showing that the species is in the second phyletic stage of development. Triptogon Roseipennis, Butler, from Hakodadi (loc. cit. Pl. XCI., Fig. 6), is represented as yellow, with seven oblique white stripes, with large irregular triangular red spots extending from the anterior edge of the stripes, nearly across each segment. It is probably in the third phyletic stage. The Indian Polyptychus Dentatus, Cramer (loc. cit. Pl. XCI., Fig. 10), is “bluish-green at the sides, with oblique purple stripes, with a broad, dorsal, longitudinal, golden-green band, bordered by subtriangular purple spots, one above each stripe.” The dorsal band is bordered by coloured stripes, which may be the subdorsal lines; but the position in which it is figured, and its very different mode of coloration, make it very difficult to compare satisfactorily with the foregoing species. The genus Ambulyx is closely allied to the SmerinthinÆ, and the two following species may be here mentioned: A. Gannascus, Stoll, figured by Burmeister (loc. cit. Pl. XIII., Fig. 5), is green, with a yellow subdorsal line, and seven oblique white lateral stripes, edged with red. A. Liturata, Butl. (loc. cit. Pl. XCI., Fig. 2), is yellowish-green above, passing into bluish-green below. The subdorsal is present on the three front segments, and is followed by a row of white, elongated patches, one on each segment, these being the upper portions of a row of lateral oblique stripes. The thickened upper extremities of the latter are edged with red, and their arrangement is very suggestive of their having arisen from the breaking up of a subdorsal line. R.M.] 105 [Butler catalogues 43 species of this genus. R.M.] 106 The deposition of eggs was accomplished by the insect laying hold of the point of a twig with its legs during flight, and curving its abdomen upwards against a leaf, the wings being kept vibrating. The egg is instantaneously fastened to the leaf. This operation is repeated from twice to four times successively, the moth then hovering over and sucking at the flowers for some time. The eggs exactly resemble in colour the young green buds of Galium. 107 [Figures of a remarkable case of gynandromorphism in a butterfly (Cirrochroa Aoris, Doubl.) have recently been published by Prof. Westwood (Trans. Ent. Soc. 1880, p. 113). On the right fore- and hind-wings of a male specimen there are patches of female colouring, thus bearing out in a very striking manner the above views concerning the non-fusibility of characters (in this case sexual) which have been long fixed. Complete (i.e. half-and-half) gynandromorphism is not uncommon in butterflies. R.M.] 108 [I have long held the opinion that the di- and trimorphism displayed by certain butterflies has originated through polymorphism from ordinary variability. I will not here enter into details, but will only cite a few instances indicating the general direction of the arguments. The phenomenon to which I refer is that so ably treated of by Mr. A.R. Wallace (see Part I., p. 32, note 20) and others. One male has often two or more distinctly coloured females, and in such cases one form of the female generally resembles the male in colour. Cases of polymorphic mimetic females may for the present be excluded, in order to reduce the argument to its greatest simplicity. Thus, in the case of native species, Colias Edusa has two females, one having the orange ground-colour of the male, and the other the well-known light form, var. Helice. So, also, Argynnis Paphia has a normal female and the dark melanic form var. Valezina. Numerous other cases might be mentioned among exotic species; and, looking at the phenomenon as a whole, it is seen to be one of gradation. For instance, our common “Blues” (Plebeius Icarus, P. Thetis, &c.) have females showing a complete gradation between the ordinary blue male and the brown female coloration. In a large number of specimens of Callosune Eupompe in my cabinet, collected in Arabia by the late J.K. Lord, there is a completely graduated series of females, varying from individuals having the scarlet tips of the fore-wings as strongly developed as in the males, to specimens without a trace of such colouring; and the same is the case with other species of this and allied genera. In such instances it is only necessary for the intermediate female forms to become extinct, in order to have true cases of dimorphism. It is significant that in 1877, when Colias Edusa appeared in this country in such extraordinary profusion, large numbers of intermediate forms were captured, these forming an uninterrupted series connecting the normal female and the var. Helice. R.M.] 109 [Many of our best describers of caterpillars, such as the late Edward Newman, Messrs. Hellins and Buckler, &c., have described the various forms of numerous polymorphic species, but not from the point of view of the comparative morphology and ontogeny of the markings. R.M.] 110 [In Butler’s revision both these species are placed in the genus Hemaris. R.M.] 111 [This species is figured also by Butler (loc. cit. Pl. XC., Fig. 9), who represents it with seven oblique green lines between the spiracles and below the subdorsal line. R.M.] 112 “Cat. E. Ind. Co. Mus.,” Pl. VIII., Fig. 2. [Walker, Lepidop. Heter. VIII., p. 92, No. 14, 1856; this species is strictly confined to Java. R.M.] 113 [Eng. ed. The caterpillar is described and figured by MilliÈre, “Iconographie des Chenilles et LÉpidoptÈres inÉdits,” tome iii., Paris, 1869; also in the Annales, Soc. Linn. de Lyon, 1871 and 1873.] [This sp. = Hemaris Croatica, Esper., of Butler’s revision. R.M.] 114 [The following additional species of the subfamily MacroglossinÆ have been figured by Butler:—Lophura Hyas, Walk. (loc. cit. Pl. XC., Figs. 1 and 2), Hong-Kong, Silhet, and Java. The larva is apparently figured in two stages, the younger being red-brown with oblique white stripes, and the head and three front segments green. The larger specimen is green, mottled with red-brown, and no oblique stripes. In both figures the subdorsal line is indicated. The whole colouring is very suggestive of protective resemblance. Hemaris Hylas, Linn., from China, Japan, Ceylon, India, Australia, and Africa (loc. cit. Pl. XC., Fig. 4). The upper part of the body is light blue, and the lower part green, the two areas being separated by a white subdorsal line bordered above with brown. The dorsal line is feebly represented. Macroglossa Belis, Cram., N. India (loc. cit. Pl. XC., Fig. 6), is figured with the ground-colour deep indigo; a conspicuous white subdorsal, and a yellow spiracular line is present; on the side of each segment, between the two lines mentioned, there is a large red spot with a yellow nucleus (? eye-spots), the spots decreasing in size towards the head and tail; these probably confer upon this species some special protective advantage. Macroglossa Pyrrhosticta, Butler, China and Japan (loc. cit. Pl. XC., Fig. 8), is greenish-white with dorsal and subdorsal lines, and seven dark oblique stripes along the sides, below the subdorsal line. Of the foregoing species Hemaris Hyas appears to be in the same phyletic stage as M. Stellatarum and M. Croatica, &c., whilst M. Pyrrhosticta is probably, together with M. Corythus and M. Gilia, in another and more advanced stage, which is also passed through by Lophura Hyas in the course of its ontogenetic development. This last species (adult) and M. Belis may represent phyletic stages still further advanced. Caliomma Pluto, Walk., of which the caterpillar is figured by Burmeister (loc. cit. Pl. XIII., Fig. 1), appears to be a case of special protective resemblance to a twig or branch of its food-plant. Figured also by Chavannes; Bull. Soc. Vadoise des Sci. Nat., Dec. 6th 1854. R.M.] 115 [Genus Pterogon, Boisd., = Proserpinus and Lophura (part). Butler, loc. cit. p. 632. The species above treated of = Proserpinus ŒnotherÆ, Fabr. R.M.] 116 [These species = Thyreus Abboti and Proserpinus GaurÆ of Butler’s revision. Of the former he states:—“Transformations described, and larva and imago figured, Am. Ent. ii. p. 123, 1870; the larva is also figured by Scudder in Harris’s ‘Correspondence,’ Pl. III., Fig. 1 (1869), and by Packard in his ‘Guide,’ p. 276, Fig. 203.” R.M.] 117 [Proserpinus (Sphinx) Gorgon, Esp. R.M.] 118 RÖsel, loc. cit. vol. iii., p. 26, note. 119 Figured and described by Abbot and Smith. [Macrosila (Sphinx) Cingulata is figured also by Burmeister, loc. cit. Pl. XII., Fig. 1. R.M.] 120 Figured in “Cat. Lep. E. Ind. Co.” 121 See the figure in Sepp’s Surinam Lepidoptera, P. 3, Pl. CI., 1848. A specimen in alcohol of the adult caterpillar is in the Berlin Museum. [The following is the synonymy of the above mentioned species:—Macrosila Hasdrubal, Walk. = Pseudosphinx (Sphinx) Tetrio, Linn.; M. Cingulata = Protoparce (Sphinx) Cingulata, Fabr.; M. Rustica = Protoparce (Sphinx) Rustica, Fabr.; Sphinx Convolvuli, Linn. = Protoparce Convolvuli; S. Carolina, Linn. = P. Carolina; the other species remain in the genera, as given above. The following additional species of SphinginÆ and AcherontiinÆ have been figured by Butler:—Pseudosphinx Cyrtolophia, Butl., from Madras (loc. cit. Pl. XCI., Figs. 11 and 13); Protoparce Orientalis, Butl., from India, China, Java, &c. (Pl. XCI., Fig. 16); Diludia Vates, Butl. from India, &c. (Pl. XCI., Fig. 18); Nephele Hespera, Fabr., from India, Australia, &c. (Pl. XCI., Fig. 20); Acherontia Morta, HÜbn., from Java, China, India, &c. (Pl. XCII., Fig. 9); and A. Medusa, Butl., from nearly the same localities as the last (Pl. XCII., Fig. 10). Most of these species fall under Dr. Weismann’s general remarks, so that it is unnecessary to give detailed descriptions. The most divergent marking is that of P. Cyrtolophia, which has a broad white dorsal line bordered with pink, and two large pink ovals on the back of the four anterior segments, the hindmost and larger of these being bisected by the dorsal line. In N. Hespera the subdorsal line is present on segments 6 to 11 only, and it is highly significant that the oblique stripes are absent from these segments, but are present on the anterior segments, where the subdorsal line fails. With reference to the larva of A. Atropos, Mr. Mansel Weale states (Proc. Ent. Soc. 1878, p. v.) that in S. Africa the ordinary form feeds generally on SolanaceÆ, whilst the darker and rarer variety is found only on species of Lantana. The following species of these subfamilies are figured by Burmeister: Amphonyx JatrophÆ (loc. cit. Pl. XI., Fig. 1); Protoparce (Diludia) Florestan, Cram. (Fig. 2); Sphinx JusticiÆ, Walk. (Fig. 3); Protoparce (Diludia) Lichenea, Walk. (Fig. 4); Sphinx (Protoparce) Cingulata, Fabr. (Pl. XII., Fig. 1); and Sphinx Cestri (Fig. 5). All these species have the characteristic Sphinx-like markings. Dilophonota Ello, Linn. (Pl. XII., Fig. 2), is greenish-brown with a yellow subdorsal line, and D. HippothÖon (Fig. 4), yellow with a whitish subdorsal. Neither of these has oblique stripes. D. Œnotrus, Cram. (Fig. 3), has neither stripes nor subdorsal, but is uniform brown above, passing into green beneath. Protoparce Albiplaga, Walk. (Pl. XIII., Fig. 2, also MÉrian, Pl. III., and Abbot and Smith, I., Pl. XXIV.), pale green with large yellow, black-bordered patches surrounding the spiracles. Pseudosphinx Tetrio, Linn. (Pl. XIII., Fig. 3), and P. Scyron (Fig. 4) are black with broad transverse belts, yellow and white respectively, encircling the middle of each segment. These light bands serve very effectively to break up the uniform surface of the large bodies of these insects, but the whole marking is suggestive of distastefulness. R.M.] 122 [The species referred to is placed by Butler in HÜbner’s genus Hyloicus. R.M.] 123 [= Ellema Coniferarum, of Butler’s revision. R.M.] 124 [= Dilophonota Ello of Butler’s revision. R.M.] 125 “Synopsis of the North American Sphingides.” Philadelphia, 1859. 126 [The larvÆ of many moths which feed on deciduous trees during the autumn and hibernate, are stated to feed on low-growing plants in the spring, before the buds of their food-trees open. On the other hand, low-plant feeders, such as TriphÆna Fimbria, &c., are stated to sometimes feed at night in early spring on the buds of trees. The habits and ontogeny of these species are of special interest in connection with the present researches, and are well worthy of investigation. R.M.] 127 “Neuer Beitrag zum geologischen Beweise der Darwin’schen Theorie.” 1873, Nos. 1 and 2. [This principle, in common with many others which have only been completely worked out of late years, is foreshadowed by Darwin. Thus, he states when speaking of inheritance at corresponding periods of life: “I could give a good many cases of variations (taking the word in the largest sense) which have supervened at an earlier age in the child than in the parent” (“Origin of Species,” 1st ed., 1860, p. 444). In the case of inherited diseases also: “It is impossible to ... doubt that there is a strong tendency to inheritance in disease at corresponding periods of life. When the rule fails, the disease is apt to come on earlier in the child than in the parent; the exceptions in the other direction being very much rarer.” (“Variation of Animals and Plants under Domestication,” 1st ed., 1868, vol. ii., p. 83.) R.M.] 128 [If the reddish-brown spots on the larva of S. Populi have the protective function assigned to them by Mr. Peter Cameron (Trans. Ent. Soc. 1880, p. 69), it can be readily understood that they would be of service to the insect in the fourth stage, and the backward transference of this character might thus be accelerated by natural selection, in accordance with the above principles. (See, also, note 100, p. 241.) R.M.] 129 [For cases of correlation of habit with protective resemblance in larvÆ, see a paper in “Ann. and Mag. of Nat. Hist.,” Feb., 1878, pp. 159, 160. Also Fritz MÜller on a Brazilian Cochliopod larva, Trans. Ent. Soc. 1878, p. 223. Mr. Mansel Weale states, with reference to S. African SphingidÆ (Proc. Ent. Soc. 1878, p. vi.), that many species when seized “have a habit of doubling up the body, and then jumping a considerable distance with a spring-like action. This is especially the case with species having eye-like markings; and it is probable that if attacked by birds in a hesitating manner, such species might effect their escape amid the grass or foliage.” Many of the defensive weapons and habits of larvÆ are doubtless means of protection from ichneumons and other parasitic foes. In the case of saw-flies, Mr. Peter Cameron has shown (Trans. Ent. Soc. 1878, p. 196) that the lashing about of the posterior part of the body may actually frighten away such enemies. The grotesque attitude and spider-like appearance and movements of the caterpillar of Stauropus Fagi are considered by Hermann MÜller (“Kosmos,” Nov., 1879, p. 123) to be means of protection from ichneumons. Among the most remarkable means of defence possessed by larvÆ is that of secreting a liquid, which Mr. W.H. Edwards has shown, in the case of certain North American LycÆnidÆ (“Canadian Entomologist.” vol. x., 1878, pp. 3–9 and 131–136), to be attractive to ants, who regularly attend these caterpillars, in the same manner and for the same purpose as they do our aphides. The mutual advantage derived by the ants and larvÆ was discovered in the case of LycÆna Pseudargiolus. Mr. Edwards states that the mature larva of this species is singularly free from Hymenopterous and Dipterous parasites:—“Why this species, and doubtless many other LycÆnÆ, are thus favoured will, perhaps, in some degree appear from a little incident to be related. On 20th June, in the woods, I saw a mature larva on its food-plant; and on its back, facing towards the tail of the larva, stood motionless one of the larger ants.... At less than two inches behind the larva, on the stem, was a large ichneumon-fly, watching its chance to thrust its ovipositor into the larva. I bent down the stem, and held it horizontally before me, without alarming either of the parties. The fly crawled a little nearer and rested, and again nearer, the ant making no sign. At length, after several advances, the fly turned its abdomen under and forward, thrust out its ovipositor, and strained itself to the utmost to reach its prey. The sting was just about to touch the extreme end of the larva, when the ant made a dash at the fly, which flew away, and so long as I watched—at least five minutes—did not return. The larva had been quiet all this time, its tubes out of sight, and head buried in a flower-bud, but the moment the ant rushed and the fly fled, it seemed to become aware of the danger, and thrashed about the end of its body repeatedly in great alarm. But the tubes were not protruded, as I was clearly able to see with my lens. The ant saved the larva, and it is probable that ichneumons would in no case get an opportunity to sting so long as such vigilant guards were about. It strikes me that the larvÆ know their protectors, and are able and willing to reward them. The advantage is mutual, and the association is friendly always.” Those who are familiar with Mr. Belt’s description of the standing armies of ants kept by the “bull’s-horn thorn” (“Naturalist in Nicaragua,” pp. 218–222) and by certain CecropiÆ and MelastomÆ, will be struck with the analogy between these and the foregoing case. R.M.] 130 [The adaptive resemblance is considerably enhanced in Catocala and in Lasiocampa Quercifolia by the row of fleshy protuberances along the sides of these caterpillars, which enables them to rest on the tree trunks by day without casting a sharp shadow. The hairs along the sides of the caterpillar of PÆcilocampa Populi doubtless serve the same purpose. (See a paper by Sir John Lubbock, Trans. Ent. Soc. 1878, p. 242; also Peter Cameron, ibid., 1880, p. 75.) It is well known to collectors that one of the best methods of finding the caterpillars of the CatocalÆ is to feel for them by day on the barks of their respective food-trees, or to beat for them at night. R.M.] 131 [See Wallace’s “Contributions to the Theory of Natural Selection,” 1st ed., p. 62. Also a paper in “Ann. Mag. Nat. Hist.” Feb. 1878, p. 159, for cases in point. RÖsel in 1746 mentioned this habit in Calocampa Exoleta. Hermann MÜller has recorded many other similar instances on the authority of Dr. Speyer; see “Kosmos,” Nov., 1879, p. 114. R.M.] 132 [Andrew Murray called attention to this fact in 1859 (“Edinburgh New Philos. Journ.,” Jan., 1860, p. 9). This view is also corroborated by the fact that no internal feeders are green; see note 142, p. 310 and Proc. Zoo. Soc. 1873, p. 159. R.M.] 133 [Proc. Ent. Soc. March 4th, 1867; and “Contributions to the Theory of Natural Selection,” 1st ed., pp. 117–122; also Darwin’s “Descent of Man,” 2nd ed., p. 325. Among the most important recent additions to the subject of the colours, spines, and odours of caterpillars, I may call attention to a paper by Fritz MÜller (“Kosmos,” Dec., 1877), the following abstract of which I communicated to the Entomological Society (Proc. 1878, pp. vi, vii):—“The larvÆ of Dione Juno and AcrÆa Thalia live gregariously, and are brown in colour; they are covered with spines, but, being of dull colours, their spiny protection (which in the case of D. Juno is very imperfect) would not preserve them unless they were distinguished as inedible at the right time, and not after being seized, in accordance with the principles laid down by Mr. Wallace. It is suggested that the social habits of the larvÆ which lead then to congregate in large numbers, make up for their want of colour, since their offensive odour then gives timely warning to an approaching enemy. The caterpillars of ColÆnis Julia and Dione VanillÆ are equally wanting in bright colours, but are solitary in their habits, and these species rest on the under side of the leaf when feeding. On the other hand, the caterpillars of Heliconius Eucrate, ColÆnis Dido, and C. Isabella, which are of solitary habits, and which freely expose themselves, are very gaudily coloured, and therefore most conspicuous. As examples of nearly allied larvÆ, of which some species are gregarious and others solitary, Fritz MÜller mentions Morpho and Brassolis, which are gregarious; while Opsiphanes and Caligo are solitary. The larva of Papilio Pompeius also is gregarious, and those of P. Nephalion, P. Polydamas, and P. Thoas are solitary.... Fritz MÜller sums up his observations by remarking that those caterpillars which live alone, and lack the bright colouring as a sign of offensiveness, must hide themselves; as those of C. Julia and D. VanillÆ. The spiny covering is much less a protection against birds than against smaller enemies; and they may, by the protective habit of living together, diffuse around themselves an offensive atmosphere, even to man, and thus gradually becoming shorter (as with D. Juno), the spines of these caterpillars become useless, and finally are altogether dropped.” See also Sir John Lubbock’s “Note on the Colours of British Caterpillars,” Trans. Ent. Soc. 1878, p. 239. Mr. Peter Cameron finds (Trans. Ent. Soc. 1880, pp. 71 and 75) that these remarks are also applicable to the larvÆ of certain saw-flies. In 1877 Mr. J.W. Slater published a paper “On the Food of gaily-coloured Caterpillars” (Trans. Ent. Soc. 1877, p. 205), in which he suggested that such caterpillars might derive their distasteful qualities from feeding on plants containing poisonous or otherwise noxious principles. A much larger number of observations will be required, however, before this view can be accepted as of general application. A beautiful illustration of the theory of warning colours is given by Belt in his “Naturalist in Nicaragua,” p. 321. All the frogs found in the woods round St. Domingo are, with one exception, protectively coloured; they are of nocturnal habits, and are devoured by snakes and birds. The exception was a species of bright red and blue colours, which hopped about by day and made no attempt at concealment. From these facts Mr. Belt concluded that this species was inedible, and on trying the experiment with ducks and fowls this was found to be the case. R.M.] 134 See the essay “Über den Einfluss der Isolirung auf die Artbilding.” Leipzig, 1872, p. 22. 136 [Eng. ed. The habit of hiding by day occurs also in those caterpillars which resemble the bark of their food-trees. Thus Catocala Sponsa and Promissa conceal themselves by day in crevices of the bark, and are, under these circumstances, only found with difficulty. Dr. Fritz MÜller also writes to me that in Brazil the caterpillars of Papilio Evander rest in this manner in large numbers, crowded together into dense masses, on the trunks of the orange-trees, which they resemble in colour.] 137 “Über den Einfluss der Isolirung auf die Artbildung.” Leipzig, 1872, p. 21. 138 I am unfortunately not able to give exact numbers showing the relative proportions of the different forms, since I have never bred S. Convolvuli from eggs, nor C. Elpenor in sufficient numbers. 140 [In the class of cases treated of in the foregoing portions of this essay, the external conditions remain unaltered during the lifetime of the caterpillar, but change of habit, and in some cases of colour, occurs when the insect has attained a size conceivable À priori, and are realized by observation, in which the environment itself may undergo change during the lifetime of the individual caterpillar. Thus, in the case of hibernating species, the colour which is adaptive to the autumnal colours of the foliage of their food-trees would not assimilate to that of the newly-opened leaves in the spring. I have already quoted (Proc. Zoo. Soc. 1873, p. 155) as instances of what may be called “seasonal adaptation,” the larvÆ of Geometra Papilionaria, Acidalia Degenararia, and Gnophos Obscurata, and many more could be named. These species undergo a change of colour before or after hibernation, the change being always adaptive to the environment. It has long been known that caterpillars which feed on flowers or on plants of variously-coloured foliage, in some cases partake of the colour of their food. See, for instance, Dr. L. MÖller’s memoir, “Die AbhÄngigkeit der Inseckten von ihrer Umgebung,” 1867, and B.D. Walsh “On Phytophagic Varieties and Phytophagic Species,” Proc. Ent. Soc. Philadelph., vol. iii., p. 403. In 1865 Mr. R. McLachlan published a paper entitled “Observations on some remarkable varieties of Sterrha Sacraria, Linn., with general notes on variation in Lepidoptera” (Trans. Ent. Soc. 1865, p. 453), in which he gave many illustrations of this phenomenon. The larva of Heliothis Peltiger, according to Mr. Reading’s description (Newman’s “British Moths,” p. 438), is another case in point. In 1874 a number of instances were published by Mr. Thomas G. Gentry in a paper entitled “Remarkable Variations in Coloration, Ornamentation, &c., of certain Crepuscular and Nocturnal Lepidopterous LarvÆ” (“Canadian Entomologist,” vol. vi., p. 85. See also W.H. Edwards’ description of the summer and autumnal larvÆ of LycÆna Pseudargiolus; Ibid., vol. x., pp. 12, 13). The caterpillars of the SphingidÆ appear also in some cases to vary in a manner very suggestive of phytophagic influences. The observations upon S. Ocellatus recorded in the previous note (p. 241) may perhaps be interpreted in this sense. In order to get experimental evidence upon this subject, I may add that Mr. E. Boscher was good enough at my request to repeat his observations, and conduct some breeding experiments during the present year (1880). In the same locality as that previously mentioned, seven larvÆ were found feeding on Salix viminalis, all of which were the bright green spotted variety; and in the same osier-bed six more were found on another species of Salix, two of these being the bluish-green variety, and the other four the bright green form. Unless we have here a local race, these observations, in connection with those of last year, tend to show that the light green form is associated with Salix viminalis. When found in the natural state feeding on apple, the caterpillar of this species is generally, perhaps invariably, the bluish-green form. In order to try the effect of breeding the larvÆ ab ovo on distinct food-plants, a large number of eggs laid by a female Ocellatus in July were divided into three batches, one being supplied with Salix triandra, another with S. viminalis, and the third lot with apple. The experiment unfortunately failed in great part, owing to most of the larvÆ dying off, three from the third lot only surviving; but these were all of the bluish-green form, which colour was shown by all the caterpillars of this batch from their earliest stage. The observation is thus so far successful, as it goes to support the view that the variety mentioned is associated with apple (and S. triandra?) My friend Mr. W.J. Argent informs me that he had a number of specimens of Sphinx Ligustri in his possession this autumn, some of which had been found on lilac and others on laurestinus, and he states that all those on the latter plant had the ground-colour distinctly darker than in those feeding on lilac. I learn also from Mr. W. Davis, of Dartford, that he found a number of these larvÆ this year feeding on ash, and that they were all differently coloured to those found on lilac or privet, being of a more greyish-green. Another case of colour-variation in larvÆ is that Emmelesia Unifasciata, specimens of which I have recently had an opportunity of examining, through the courtesy of Mr. W. Davis. This species feeds on the seeds of a species of Bartsia when the capsules are in various stages of growth, and (omitting details of marking) those caterpillars found on the green capsules were green, whilst those on the brown capsules were of a corresponding colour. On the whole I am inclined to believe that sufficient importance has not hitherto been given to phytophagic variability as a factor in determining larval coloration, and a large field for experimental investigation here lies open for future work. The obscure chemico-physiological processes which may perhaps be shown by such researches to lead to phytophagic variation, cannot, I am persuaded, produce any great divergence of character if unaided; but when such causes of variability play into the hands of natural selection variations of direct protective advantage to the species, we can easily see that this all-important agency would seize upon and perpetuate such a power of adaptability to a variable environment. (See Proc. Zoo. Soc. 1873, p. 158, and “Nature,” vol. xiv., pp. 329 and 330.) R.M.] 141 [In 1879 Mr. George Francis, of Adelaide, forwarded from the latter place a number of moths (a species of AnapÆa) together with their larvÆ (in alcohol) and cocoons (Proc. Ent. Soc. 1879, p. xvi), and in an accompanying note he stated that the male larva when living is of “a bright emerald green, with red and pink markings on the back, and yellow, black, and white streaks on the sides.” The male larva is described as being smaller than the female, and as possessing all the brilliant colours, the latter “having no red markings, but only white, yellow, and green, with a little black.” I was at first disposed to think that we might be dealing here with two distinct species having differently marked larvÆ; but Mr. Francis this present year (1880) forwarded a large number of the living cocoons of this species, which I separated according to size, and, on the emergence of the moths (August), I found that all those from the small cocoons were males, and those from the larger cocoons females. There can be no doubt, therefore, that we have but one species in this case, the larva of which presents the remarkable phenomenon of sexual difference of coloration. As an analogous fact I may here mention the well-known case of Orgyia Antiqua, the larva of which differs in the colour of the tufts of hair according to sex. R.M.] 142 [I have already given reasons for suspecting that the colour of green caterpillars may be due to the presence of chlorophyll (or some derivative thereof) in their tissues (see Proc. Zoo. Soc. 1873, p. 159). This substance appears to be one of great chemical stability, and, according to Chautard, who has detected it in an unaltered state in the tissues of certain leaf-feeding insects by means of its absorption spectrum (“Comp. Rend.” Jan. 13th, 1873), it resists the animal digestive processes (Ann. Ch. Phys. [5], iii., 1–56). If this view should be established by future observations, we must regard the green colour of caterpillars as having been produced, when protective, from phytophagic variability by the action of natural selection; and the absence of colour in internal feeders, above referred to, is only secondarily due to the exclusion of light, and depends primarily on the absence of chlorophyll in their food. In connection with this I may adduce the fact, that some few species of Nepticula (N. Oxyacanthella, N. Viscerella, &c.) are green, although they live in leaf-galleries where this colour can hardly be of use as a protection; but their food (hawthorn and elm) contains chlorophyll. See also note 130, p. 293. Further investigations in this direction are much needed. R.M.] 143 [The same applies to Pseudoterpna Cytisaria, also feeding on broom at the same time of the year. The most striking cases of adaptive resemblance brought about by longitudinal stripes are to be found among fir and pine feeders, species belonging to the most diverse families (Hyloicus Pinastri, Trachea Piniperda, Fidonia Piniaria, &c., &c.) all being most admirably concealed among the needle-shaped leaves. R.M.] 144 The geographical distribution of the dark form indicates that in the case of this species also, the form referred to is replacing the yellow (green) variety. Whilst in the middle of Europe (Germany, France, Hungary) the dark form is extremely rare, in the south of Spain this variety, as I learn from Dr. Noll, is almost as common as the yellow one. I hear also from Dr. Staudinger that in South Africa (Port Natal) the dark form is somewhat the commoner, although the golden-yellow and, more rarely, the green varieties, occur there. I have seen a caterpillar and several moths from Port Natal, and these all agree exactly with ours. The displacement of the green (yellow) form by the dark soil-adapted variety, appears therefore to proceed more rapidly in a warm than in a temperate climate. [Eng. ed. Dr. Noll writes to me from Frankfort that the caterpillar of Acherontia Atropos in the south of Spain does not, as with us, conceal itself by day in the earth, but on the stems underneath the leaves. “At Cadiz, on the hot, sandy shore, Solanum violaceum grows to a height of three feet, and on a single plant I often found more than a dozen Atropos larvÆ resting with the head retracted. It can easily be understood why the lateral stripes are blue when one has seen the south European SolaneÆ, on which this larva is at home. Solanum violaceum is scarcely green: violet tints alternate with brown, green, and yellow over the whole plant, and between these appear the yellow-anthered flowers, and golden-yellow berries of the size of a greengage. Thus it happens that the numerous thorns, an inch long, between which the caterpillar rests on the stem, pass from violet into shades of blue, red, green, and yellow.”] 145 [For Mr. J.P. Mansel Weale’s remarks on the habits of certain ocellated S. African Sphinx-larvÆ see note 129, p. 290. R.M.] 146 [Some experiments with the caterpillar of C. Elpenor, confirming these results, have been made by Lady Verney. See “Good Words,” Dec. 1877, p. 838. R.M.] 147 [The eye-spots on Ch. Nerii have thus been supposed by some observers to be imitations of the flowers of the periwinkle, one of its food-plants. See, for instance, Sir John Lubbock’s “Scientific Lectures,” p. 51. R.M.] 148 “On Insects and Insectivorous Birds,” Trans. Ent. Soc. 1869, p. 21. 149 Ibid., p. 27. 150 [Messrs. Weir and Butler inform me that they have not experimented with Sphinx-larvÆ. R.M.] 151 [It appears that the nauseous character of these last butterflies is to a certain extent retained after death, as I found that in an old collection which had been destroyed by mites, the least mutilated specimens were species of Danais and EuplÆa, genera which are known to be distasteful when living, and to serve as models for mimicry. See Proc. Ent. Soc. 1877, p. xii. R.M.] 152 [This bears out the view expressed in a previous note 129, p. 290, that the grotesque attitude and caudal tentacles are more for protection against ichneumons than against larger foes. R.M.] 153 These experiments, as already mentioned above, were not made with the common German lizard (Lacerta Stirpium), but with the large South European Lacerta Viridis. 154 Thus, Boisduval states of this caterpillar, which in Provence lives on Euphorbia esula and allied species:—“Its resemblance to a serpent, and its brilliant colour, permit of its being easily discovered.” This was written in 1843, long before natural selection was thought of. 155 Or some other extinct analogously-marked species. 156 [See Darwin’s remarks on the struggle for life being most severe between individuals and varieties of the same species “Origin of Species,” 6th ed. p. 59. R.M.] 157 [Compare this with Darwin’s remarks on “analogous variations,” “Origin of Species,” 6th ed., p. 125. R.M.] 158 “Zoologische Studien auf Capri. II. Lacerta muralis cÆrula, ein Beitrag zur Darwin’schen Lehre.” Leipzig, 1874. [The subject of colour-variation in lizards has been much discussed in “Nature” since the publication of the above mentioned essay; see vol. xix., pp. 4, 53, 97, and 122, and vol. xx., pp. 290 and 480. R M.] 159 “Über die Berechtigung der Darwin’schen Theorie.” Leipzig, 1868. See also the previous essay “On the Seasonal Dimorphism of Butterflies,” pp. 112–116. 160 [Mr. A.G. Butler has recently advanced the view that this family is not allied to the SphingidÆ, but is related on the one side to the Pyrales, and on the other to the GelechiidÆ. See his paper “On the Natural Affinities of the Lepidopterous Family ÆgeriidÆ,” Trans. Ent. Soc. 1878, p. 121. R.M.] 161 I am indebted to my esteemed colleague, Prof. GestÄcker, for the knowledge of this specimen. 164 [The question here also suggests itself as to why the dorsal line should not have been the primary longitudinal stripe, seeing that such a marking is almost naturally produced in many caterpillars by the food in the alimentary canal; or, in other words, why has not natural selection taken advantage of such an obvious means of producing a stripe in cases where it would have been advantageous? In answer to this I may state, that in large numbers of species the dorsal line has thus become utilized; but in the case of large caterpillars resting among foliage, it can be easily seen that light lateral (i.e. subdorsal) stripes, are more effective in breaking the homogeneity of the body than a dorsal line only slightly darker than the general ground-colour. Lateral lines are in fact visible from two directions of space. If a caterpillar thus marked be placed on a twig, these lines are visible when we look at the creature’s back or at either side. That the subdorsal are therefore the primary lines, as shown by Dr. Weismann’s observations of the ontogeny of many of the SphingidÆ, is quite in harmony with the view of their having been produced by natural selection. R.M.] 165 “Die Darwin’sche Theorie. Elf Vorlesungen Über die Entstehung der Thiere und Pflanzen durch NaturzÜchtung.” 2nd ed., Leipzig, 1875, p. 195. 166 [In the following species, already mentioned in previous notes, the oblique stripes are bounded at their upper extremities by a conspicuous subdorsal line:—Acosmeryx Anceus, Cram.; Sphinx Cingulata, Fabr.; Pachylia Ficus, Linn.; P. Syces, HÜbn. In Pseudosphinx Cyrtolophia, Butl., the oblique white stripes, beautifully shaded with pink, run into the white pink-bordered dorsal line, so that when seen from above the markings present the appearance of the midrib and lateral veins of a leaf, and are probably specially adapted for this purpose. R.M.] 167 [The dorsal line as well as the oblique stripes is present in the caterpillar of Smerinthus Tartarinovii, MÉnÉt.; and in Ambulyx Gannascus, Stoll., the oblique stripes are bounded above by a subdorsal line, as in the species named in the preceding note. R.M.] 168 Cat. Lep. East India Co., Pl. XI. 169 [Compare this with Darwin’s “Origin of Species” (1st. ed. p. 440), where it is stated that when an animal, during any part of its embryonic career, is active, and has to provide for itself, “the period of activity may come on earlier or later in life; but whenever it comes on, the adaptation of the larva to its conditions of life is just as perfect and beautiful as in the adult animal. From such special adaptations the similarity of the larvÆ or active embryos of allied animals is sometimes much obscured.” R.M.] 170 [For Fritz MÜller’s application of this principle to the case of certain groups of Brazilian butterflies see Appendix II. to this Part. R.M.] |
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