DENTITION.

IN the preceding pages it may have been observed that the adage, ‘There are no rules without exceptions,’ occurs so frequently in ophidian physiology that the latter are almost in the majority. Concerning the teeth especially, the forms of dentition in the various families, the distinction of species by them, the size and position of poison fangs, etc., the rules involve so many exceptions that we can perhaps render the subject less perplexing by dispensing with rules altogether. ‘The gradations of teeth are very imperceptible,’ said Prof. Huxley in his lecture at the London Institution. So numerous are their stages of development that there is really no well-defined gap between the venomous and the non-venomous species. ‘We do not know for certain whether the ordinary teeth are poisonous or not,’ Huxley also said. The recent researches into the nature of salivary secretions will throw more light on this subject. A large non-venomous snake, like other normally harmless animals, if biting angrily, with its abundant salivary glands pouring secretions into its mouth, might inflict a very ugly wound, especially on a feeble or frightened victim.

A few rules may, however, safely be offered as ‘without exception,’ and these I will point out in order to clear the way a little towards a better comprehension of the exceptional ones.

All true snakes, poisonous or not, that have teeth at all, have the six jaws described in the first chapter, viz. the right and left upper jaw, the right and left lower jaw, and the right and left palate jaw. The latter are called ‘jaws,’ not anatomically, but merely as answering the same purpose, being furnished with teeth; each true jaw and the palate being considered as two or a pair, on account of the independent action imparted to each by the especial muscles and the elastic tissue which unites them, where in the higher animals they are consolidated.

With but one exception (the egg-eating Oligodon or Anodon family) all other true serpents, whether venomous or not, possess the two rows of palate teeth.

All can move or use each of the six jaws, or any two, three, or more of them independently, as we observed in feeding, some of the six holding the prey while others move on. Some writers have conveyed the idea that there is a regular alternation and even rotation of the jaws in feeding, No. 1, 2, and so on in succession till all the six have moved, and then No. 1 in its turn again; but observation inclines me rather to decide that there is no other rule than the feeder’s individual convenience, according to what its teeth may be grasping, any more than there is in other creatures that without reflection or intent, and not strictly in turn, eat now on one side of the mouth and now on the other (except in the case of some poor mortal with the toothache, when, having only the two jaws, his distressful efforts are chiefly directed towards relieving that side of its ordinary duties). Snakes, for aught we know, may have the toothache: loose teeth they frequently have; they suffer from gum and mouth affections too, and no doubt can at such times relieve a whole jaw of its work.

In all true snakes the teeth are long, conical, and curved: not planted perpendicularly, but directed backwards; these long, fine, claw-shaped instruments presenting a formidable obstacle against the retreat of a creature once seized by them. Their arrangement is a species of trap, like the wires of a mouse-trap: to enter being easy enough, but to escape against the spikes being impossible.

All snakes renew their teeth throughout life. Except fishes, therefore, no creatures are so abundantly supplied with teeth as are the Ophidia.

On account of this continual loss and replacement of teeth, the number is rarely so fixed and determinate as to be characteristic of the species. Probably no two snakes, not even brothers and sisters of the same brood, may possess precisely the same number of teeth at a given age; because they are so easily loosened and lost, that the normal number might rarely occur in all the members of the same family at the same time. In the scientific language of Rymer Jones, ‘the facility for developing new tooth germs is unlimited, and the phenomena of dental decadence and replacement are manifested in every period of life.’

Says Nicholson, ‘The teeth are replaced not merely when accident has broken off the old ones, but they are all shed at more or less regular intervals, coinciding with the casting of the epidermis.’ Not on each occasion of sloughing, as we may, I think, understand this, but, like the casting of cuticle, contingently, according to the condition of the individual. Not altogether, either, or at certain periods of life, as a child loses his first teeth and gets a second crop, or as an adult cuts his wisdom teeth, but ‘a crop of young teeth work their way into the intervals of the old teeth, and gradually expel these latter.’ All the spaces and depressions between the maxillary and palatine rows are occupied by the matrix of tooth germs. Not a cut can be made in this part of the palate without the knife turning up a number of young teeth in every stage of development.[92]

Independently of this accidental number, the maxillary presents certain phases which characterize families. For instance, a true viperine snake has in the upper jaw fangs only: non-venomous snakes have a whole row of from fifteen to twenty-five maxillary teeth, and in intermediate species their normal numbers vary considerably. Some of the highly poisonous families, notably the cobras and the sea snakes, have a few simple teeth in addition to fangs. The length of the jaw, therefore, diminishes in proportion to the number of teeth it bears. Only the viperine snakes are limited to the poison fang in the upper jaw; but fangs, like the simple teeth, are shed, broken, or lost, and renewed continually.

Behind the one in use—the functional fang—others in various stages of development are found—‘a perfect storehouse of new fangs,’ as Mr. F. Buckland in his facetious style called them; ‘lying one behind another like a row of pandean pipes.’ In the skeletons of viperine snakes these may readily be observed. In the living example they are enclosed in a capsule, hidden by the loose gum sheath, called a gingeval envelope. So when the functional fang meets with an accident, or falls out in the order of things, the supplementary fangs in turn supply its place, each becoming in time firmly fixed to the jaw-bone, and ready to perform the office of its predecessor.

Poison fangs succeed each other from behind, forwards; the simple teeth from the inner side, outwards.

Before proceeding further, it may be well to explain that what is meant by the true snakes in the foregoing rules, are those which do not possess the lizard features; Anguis fragilis, and some of the burrowing snakes which approach the lizards, not having the palate teeth. But here again we are tripped up with exceptions, since we are told that in dentition the boas are allied to the lizards; yet they have palate teeth.

The importance of dentition in distinguishing snakes is seen in the names assigned to them from their teeth alone. In giving a few of these terms we enable the reader to perceive at once, not only how very varied are the systems of dentition, but in what way they vary, the words themselves conveying the description.

The names here given are without reference to venomous or non-venomous serpents, but only as belonging to certain families whose teeth present characteristics sufficiently marked to be named by them.

From odous, odontos, a tooth.

In Dumeril’s system very many families, including sometimes several of the above, are grouped according to their teeth, thus:—

And some others whose names are equally descriptive.

These various characters, with the exception of Aproterodontes, which refers to the under jaw, have reference to the upper jaw only. It might be tedious to the reader to enter into a minute description of each of the above groups: sufficient for our present purpose is it to show that such varieties exist, and that a simple, even row of teeth, as a family distinction, is oftener the exception than the rule. Some of the teeth increase in size posteriorly, others are largest anteriorly; others, again, are larger towards the middle of the jaw, and decrease at either end. Some harmless snakes have ‘fangs,’ that is to say, fang-like teeth, but not connected with any poison gland, and at the back instead of the front of the jaw. Again, there are some non-venomous species that have the power of moving these fang-like teeth, raising or depressing them as vipers move their fangs, and as will be further described presently. Some grooved teeth convey an acrid saliva, others are without any modification of saliva, the long teeth being of use in holding thick-skinned prey.

Thus we find every gradation both in number and in form until we come to the true fang, the ‘murderous tooth’ of the terrible cobra, the hydrophidÆ, and the viperidÆ. And noteworthy it is that the fewer the teeth in the maxillary bone the more terrible are they. Fig. A of the four illustrations given opposite is the jaw-bone of the Indian Rat snake, Ptyas mucosus, already ‘honourably mentioned’ in these pages. The illustration being taken from Fayrer’s Thanatophidia, may be received as a faithful representation. This conveys a good idea of jaws generally in non-venomous snakes of that size, say from six to ten feet long. In some of the smaller kinds the jaw and palate teeth are so fine as to be almost imperceptible to the naked eye. To the touch they feel like points of the finest pins. Draw your finger along or press it against a row of ‘minikin pins,’ and you will form a correct idea of these tiny weapons. I have often felt when I could not see them in the mouth of a small harmless snake. Pass the tip of your little finger gently along them towards the throat, and they are almost imperceptible even to the touch; but in withdrawing your finger against the points, you feel how excessively fine they are.

The accompanying illustrations are from nature, and exemplify the various lengths of jaw in four snakes, not differing very greatly in size.

Fig. A. Ptyas mucosus, with simple teeth only. That they are not very regular is probably owing to the stages of growth in those that have replaced others.

Fig. B. A venomous snake, Bungarus, the ‘Krait,’ with a fixed fang in front and a few simple teeth behind it.

Fig. C. Jaw of the cobra, with a longer fixed fang, and one or two simple teeth behind it.

Fig. D. The shortest jaw of them all, that of the Indian viper Daboia, in which the maxillary is reduced to a mere wedge of bone. These, with four or five reserve fangs, are here folded back ‘depressed.’ A few palate teeth are also seen.

Having given a slight sketch of the various forms of dentition, and arrived at ‘fangs,’ we may recapitulate, in what Nicholson calls ‘roughly speaking,’ four stages of development in these latter.

First, the ‘fangs’ of the harmless snakes, such as Lycodon, Xenodon, Heterodon, etc., which have no poison gland, but whose saliva may be slightly and occasionally injurious.

Secondly, those having a salivary gland secreting poison and a grooved fang in front of some simple teeth, HydrophidÆ.

Thirdly, the maxillary bone shorter, bearing one poison fang with a perfect canal, and one or two teeth behind it. In some of these there is a slight mobility.

Fourthly, the maxillary bone so reduced as to be higher than long, and bearing only a single tooth, viz. a long, curved, and very mobile fang, Viperina.

These four classes, be it observed, are only designated ‘roughly speaking.’ Nicholson describes a close gradation in the development of the poison glands also to correspond with those almost imperceptible stages. The poison gland is after all only a modified salivary gland. It lies behind the eye, whence the venom is conveyed by a duct to the base of the fang, down along it, and sometimes through it, and is emitted at what we may for the present call the point, into the wound made by it, something on the principle of an insect’s sting. As when inserting the sting the pressure forces the poison out of a gland at its base, so does the pressure of certain muscles act upon the poison gland when a snake opens its mouth to strike. In some of the most venomous, viz. the viperine families, the largely developed glands give that peculiar breadth to the head. There is a hideous, repulsive look about some of these, that seems to announce their deadly character, even to those who see one for the first time. The evil expression of the eye, with its linear pupil; the peculiar curve of the mouth, with its very wide gape downwards, and then up again, are unmistakeably treacherous, venomous, vicious.

Like all other animal secretions, the poison is produced, expended, and renewed, but not always with equal rapidity; climate, season, and temperature, as well as the vigour of the reptile, influencing this secretion. The hotter the weather, the more active the serpent and all its functions. When the poison gland is full and the snake angry, you may see the venom exuding from the point of the fang, and by a forcible expiration the reptile can eject it. I have seen this in the little Echis carinata and its congener the Cerastes. I am not certain whether the Cerastes hisses or not, but under terror or excitement it moves itself about in ‘mystic coils’ as Echis does, producing a similar rustling noise with its scales; but both of them, if angry, will strike at you with a sound which may be compared with a sneeze or a spit, at the same time gnashing their mobile fangs and letting you see that they have plenty of venom at your service. They may almost be said to ‘spit’ at you, though literally it is the mouth ‘watering with poison,’ combined with the natural impulse to strike, which produces this effect. We can, however, by this judge of the force with which the venom is expelled, which in a large viper must be considerable.

Travellers have told us that a serpent ‘spouts poison into your eye.’ If an angry one strike, but miss its aim, the poison is then seen to fly from its mouth, sometimes to a distance of several feet. Whether a snake is so good a marksman as to take certain aim with this terrible projectile, or whether he possess sufficient intelligence to attempt it, we may doubt. Dr. Andrew Smith tells us that this belief prevails among the natives of South Africa.

A bright object always attracts snakes, and some victimized traveller’s eyes may have been remarkably brilliant, and in consequence smarted under the accident. Be that as it may, the poison is sometimes so abundant that you may see it flow from the mouth over the prey. The glands being excited, just as are the salivary glands of mammals, the mouth ‘waters’ with poison. In the Hamadryad I have seen it flow, or more correctly ‘dribble,’ down over the snake it was eating. This noxious secretion assists digestion in the same way that the ordinary saliva in the human mouth does. Says Dr. Carpenter, ‘The saliva prepares food for the business of the stomach; and if the ordinary operations of mastication and insalivation be neglected, the stomach has to do the whole work of preparation as well as its own especial duty of the digestion.’ That the digestive powers of snakes are strong, we know from the fact that nearly all animal substances are converted to nutriment in the stomach of a healthy snake. The abundant saliva must be a powerful agent in the process, because mastication takes no share in the work. This has become more than mere conjecture, since recent experiments have shown that snake venom possesses strong peptic qualities; that, like pancreatic juice, it will even dissolve raw meat and albuminous substances. Recent experiments have also shown that the salivary gland is the laboratory in which the poison of venomous serpents is elaborated; that ordinary saliva is there intensified, concentrated, and endowed with its toxic properties.

During the two hundred years that have witnessed the development of natural history into a science, many and various have been the methods of zoological and particularly of ophiological classification. A few of these methods are sketched out in chap. ii. It will be seen that the character of the teeth had not for a long while much weight in classifying snakes. According to Schlegel, Klein in 1755 was the first to separate the venomous from the non-venomous snakes in classification. But after him LinnÆus, then the greatest naturalist of modern times, distinguished snakes chiefly by the form of the ventral and sub-caudal plates; so that in the six genera which he established (AmphisbÆna, Cecilia, Crotalus, Boa, Coluber, and Anguis), rattlesnakes and boas, colubers and vipers, with others of the most opposite characters, were jumbled up together; and the little burrowing blindworm and the venomous sea snakes were supposed to be related, because they neither of them had ventral scales! On account of his vast researches and great reputation, subsequent naturalists were slow to entirely overthrow his system and to venture on reforms of their own, and our cyclopedias are suffering to the present day from the confusion of the various methods of classification adopted by so many naturalists, as a few quotations presently will show. Dandin, 1802, though his work was reckoned by Schlegel the most complete up to his time, comprehended all the venomous snakes under the head of ‘vipers.’ Cuvier divided the vipers (with crochets mobiles) from those with fixed fangs; but yet was unsound in many other respects, confounding the ElapidÆ with the ViperidÆ, although he professed to separate them. Another confusion arose out of the word cobra, Portuguese for snake, so that wherever the Portuguese settled most snakes were Cobras. In India the English have retained the name Cobra for the snakes with the hood, which name is now confined to the one group, Capella.

‘The characters of dentition offer in a great many cases a decisive method for distinguishing the species,’ says GÜnther; ‘but as regards the combination of species into genera and families, it is of no greater importance than any other external character by itself.... Still I am always glad to use the dentition as one of the characters of genera and species whenever possible—namely, whenever it corresponds with the mode of life, the general habits, and the physiology.’[93]

Since the publication of Dr. GÜnther’s work, The Reptiles of British India, 1864, the distinctions of the various types of dentition seem to have been more clearly comprehended; and as this work is the accepted authority among English ophiologists, and will best commend itself to the reader, it shall be our guide in the present attempt to simplify much complication.

The five groups of snakes described in chap. ii. are divided into three sub-orders of Ophidia as follows:—1. Ophidia colubriformes (the harmless snakes). 2. Ophidia colubriformes venenosi (those which, not having the viperine aspect just now described, are the more dangerous from their innocent appearance). 3. Ophidia viperiformes (the viperine snakes).

Although apparently named from their form only, it is the teeth which have chiefly to do with these latter distinctions, as will be seen on reference to the dotted examples of upper jaws. The first have the six rows of simple teeth (four above, as seen, and the lower jaw teeth), in all from 80 to 100 perhaps. The second have the two rows of palate teeth, the lower jaw teeth, and a fixed fang on each upper jaw, with one, two, or more simple teeth in addition. The Australian poisonous serpents are nearly all of this group, the only viperish-looking one, the ‘Death adder,’ having fixed fangs like the cobras. The sea snakes and the ElapidÆ are included. The third have only four rows of simple teeth, viz. those of the lower jaws and those of the palate, with a solitary moveable fang in each upper jaw.

Fayrer divides the poisonous snakes of India, again, into four families, viz. ElapidÆ and HydrophidÆ, with fixed fangs; and ViperidÆ and CrotalidÆ, with mobile fangs.

But without so many perplexing distinctions, I hope to be able to interest the reader in that wonderful piece of mechanism, the poison fang, and by the aid of the authorities to represent it in simple language.

We have long been accustomed to read that a serpent’s fang is a ‘perforated tooth’ or a ‘hollow tube,’ as if a miniature tusk had a hole bored through its entire length, the poison entering at the root and flowing out again at the point. This is not strictly the case. Fangs in their construction are not absolutely ‘hollow,’ with ivory on the outside and pulp on the inside, but are as if you had flattened out an ivory tusk and folded or wrapped it over again, so as to form a pointed tube. It would then have dentine both on the outer and inner surface. This involution may be compared with that seen in a long narrow leaf, in which the larva of an insect has enwrapped itself. The various degrees of involution are extremely close, as also would be the forms of leaves and the extent of curling which each caterpillar had effected. Some fangs are folded so as to leave the—join, we will call it, easily perceptible. Others leave a groove more or less evident; while in others the fold is so complete as to have disappeared entirely. Schlegel, in describing the insensible passage from solid teeth to fangs, affirms that traces of the groove are always perceptible: ‘On dÉcouvre toujours les traces de la fente qui rÉunit les deux orifices pour le venin.’[94]

In a mixed collection of thirty odd fangs of various snakes lent to me by Holland, the keeper, for examination, and sent all together in a little box, there were few in which I could not discern the join. The keeper was not sure to which snakes each belonged, excepting one or two of the largest, which were those of a puff adder. Those of the larger CrotalidÆ I could identify by the peculiar curve. In a functional fang of the ‘bushmaster’ (Lachesis mutus), which I myself took from its jaw, there is a well-defined line, like a crack, the whole way down, from the base to the slit; in a rattlesnake fang, also in my possession, there is a faint appearance of this line or join; and in a young Crotalus fang it is still there,—only a faint crack, such as you would contemplate with alarm in your egg-shell china, still there it is.

It is scarcely necessary to explain that fangs differ in size in different families, as well as proportionately to the size of the possessor. In sea snakes they are not much larger than the simple teeth behind them. In the Cobra they are larger than in the Bungarus; in the viper they attain their largest size.

But in one respect all fangs agree, and that is in their delicacy and fineness. Under the microscope, the stronger the lens the greater the degree of exquisite polish and sharpness revealed. To handle those of very young vipers is as difficult as it would be to handle fine needle-points of similar length. One can compare them with nothing else, except perhaps the fine thorns of the sweet briar, which are equally unmanageable, and, as compared with manufactured articles, equally exquisite.

Sir Samuel Baker describes the fangs (both functional and supplementary) of a puff adder which he found. His words, if not strictly scientific, are so graphic as to convey a true idea of these terrible weapons. The viper was five feet four inches long, and fifteen inches in girth in its largest part. The head was two and a half inches broad. Sir Samuel counted ‘eight teeth’ (fangs), and secured five of them, the two most prominent being nearly one inch long. ‘The poison fangs are artfully contrived, by some diabolical freak of nature, as pointed tubes, through which the poison is injected into the base of the wound inflicted. The extreme point of the fang is solid, and is so finely sharpened that beneath a powerful microscope it is perfectly smooth, although the point of the finest needle is rough!’[95] He describes the aperture in the fang as like a tiny slit cut in a quill.

This ‘slit’ is a very important feature in the fang, and is the cause of much trouble in deciding whether a bitten person has been poisoned or not. It is in reality a very small space near the point, where the involution of the fang is incomplete, that is, where it has remained unjoined. This is to permit the emission of the venom. It is not close to the point, which, as Sir S. Baker affirms, is solid. Being solid, it is stronger and sharper, penetrating the skin of the victim more easily, and making way for the venom which in viperine fangs then follows and escapes through the slit into the wound. By this we comprehend how a person may receive a puncture only, or a scratch with this extreme but solid point, but not deep enough for the poison to enter. The space between the lines at a in the next illustration shows where this slit in the fang is found. In the larger fangs it may be readily discerned with the naked eye: under a magnifying glass it is distinguishable in all. It is distinct in the fangs of the young Jararacas now before me, and extends nearly half-way up the fang in these.

The examples of fangs here given are all from nature, and as near to the exact size as it is possible to be in delineating objects of such exceeding fineness and delicacy. Excepting the Xenodon’s and the baby viper’s, the others belong to the CrotalidÆ, whose fangs are mostly distinguishable by a slight double curve or flange. The viperine fang is a continuous curve (see f), but in the Crotalus the point curves very slightly back again and downwards.

For the Brazilian specimens, I am indebted to Dr. Arthur Stradling, who presented me with the snakes, out of whose jaws I myself procured them. In this Lachesis there were two fangs visible on one side, and only one on the other, viz. the functional pair, and one nearly ready to replace one of these. In addition to the pair were four reserve fangs hidden under the functional one on the right side. I say ‘under,’ because anatomically they were beneath, though locally above when the snake was in its natural position. All these five fangs I got from only one side, and in addition some others too small to represent. There may be yet more in the membranous capsule, as mine was a sadly unscientific search for them, and without any very powerful magnifier. Like Charas, I ‘grovelled’ for them! From a young Jararaca I also got out the functional and four or five supplementary fangs from one side, also an exceedingly small and short jaw-bone, leaving the other side undisturbed. Even the principal fang (d) is too fine to represent faithfully in printer’s ink; the others are to the naked eye and to the touch almost impalpable. When we reflect on the exquisite sharpness and finish of these minute weapons, and the fatal injury they are capable of inflicting, we are filled with awe and amazement at the virulence of the subtle fluid which oozes through that almost invisible aperture. The brother of this tiny African viper (f), when only a few hours old, struck a mouse, which was dead in less than one minute. The whole forty-six of them (p. 321) were born with the ‘murderous teeth’ in their vicious little jaws. The fang here represented was loose in its mouth. A pair of perfect functional fangs remained.

Picture to yourselves the intensity of that invisible molecule of venom, which could ooze through an equally invisible aperture in this last diminutive weapon, and be fatal to life in a minute of time! From the effects observed on victims, I am inclined to place these large African vipers amongst the most venomous of all serpents of their size.

It may be of interest to remark that the fang of the baby viper found loose in its mouth does not resemble those remaining, either in form or structure. That it cannot be a jaw tooth is evident from its size. Jaw and palate teeth there are, but discernible only to the touch, and under a magnifying glass. The fixed fang from the side on which I found this loose one, is a trifle shorter, and much finer than its fellow. In the loose one here given I can hardly discern any involution at all, but on touching it with the inky point of a fine needle, the stain shows it be hollow, and clearly so, at its base. In the two fixed fangs, however, the involution is so incomplete that, minute as they are, the point of a very fine needle can be drawn all down them without slipping off.

One of them, the larger, on being touched with ink, revealed this open groove or incomplete involution so distinctly that I tried the other and was convinced at once. The loose one may be a first and only half-developed fang. They are almost as transparent as glass. I requested the keeper to look into the mouths of those subsequently dead, but he found no other loose fangs. Of the remaining forty-five deceased, let us hope those into whose hands they have fallen will be able to throw some further light on the development of fangs in very young vipers. Fayrer tells us that a young cobra is not venomous until it has cast its first skin, which is usually within a fortnight. White of Selborne found no trace of fangs in young vipers which he examined with a lens; but these had not yet been born. The possible cause of functional development in this little viper’s fangs may be found in chap. xxiv. of this work.

Another erroneous impression regarding fangs has been produced by confusing those that are ‘fixed’ and those that are ‘moveable.’ All truly are fixed firmly into the jaw; but in the viperine snakes the very short bone itself is moveable by a volitionary action, so that it partially ‘rotates,’ and with it the fang. The ElapidÆ have fixed or ‘permanently erect’ fangs, and when the mouth is closed these fit into a depression in the lower jaw. Viperine fangs only can be erected or depressed at pleasure. It is those which spring into place for use like a pen-knife half opened, and which when at rest are folded back, like the knife shut up again. This action has been most lucidly described by Coues in connection with the CrotalidÆ, under which head I will quote from his paper. Schlegel himself is not very clear in his distinctions between those serpents that have ‘moveable’ fangs and those which have not, but Cuvier had already described them as crochets mobiles. Indeed, it is since the date of Schlegel’s work that more complete investigations have revealed closer anatomical distinctions. We therefore find in some of our highest-class encyclopedias, if not of recent date, mis-statements regarding fangs which unfortunately have been quoted in many works. ‘Venomous serpents depress their fangs,’ says Schlegel’s translator, true to the text, but as if it were common to all. Describing deglutition, Schlegel says ‘the same in all’ ‘sans en excepter les venimeux, qui lors de cet acte redressent leur crochets et les cachent dans la gaine des gencives, pour ne point les exposer À des injures.’[96] This, however, is the case with the Viperina only. It is common, for the reasons just now assigned, to find the cobra classed among the vipers, in some popular encyclopedias; and in one, a valuable and generally trustworthy American edition of 1875, we read, ‘moveable fangs like the cobra, viper, and rattlesnake.’ A cobra has not moveable fangs. Another, an excellent English edition, but of not very recent date, includes all venomous snakes under the head of ‘vipers;’ a third in general terms states that ‘venomous snakes have no teeth in the upper jaws, excepting the fangs, and that the opening of the mouth brings these into position;’ whereas it is now known that a viper can open its mouth and yet keep its fangs depressed and sheathed. In several other encyclopedias the description of fangs is suited to vipers only.

It is not necessary to designate names, as these things will be set right in the new editions. They are mentioned more with a view to show that ophiology has advanced with rapid strides of late, rather than presumptuously to criticise our standard works. Perhaps in another twenty years my own poor efforts will be exposed as ‘old-time misconceptions.’

The renewal of poison fangs is another subject of interest to ophiologists: how the next supplementary fang becomes fixed, anchylosed to the jaw-bone; and how and when the connection with the poison duct is completed. Mr. Tombes, in a paper read before the Royal Society in 1875, describes a ‘scaffolding’ of bone thrown out to meet and grasp the new fang, to ‘interdigitate and fix it in its place; this soft bone rapidly developing and hardening.’ Sufficiently marvellous is the functional fang in itself; the insertion of the venom, a mode of subcutaneous injection invented long before the doctors thought of it. ‘A most perfect hypodermic syringe,’ Huxley calls it. Suddenly the hypodermic syringe is removed, say by accident, by force, or by gradual decay, and all connection with the gland is cut off; yet within a given period a second, a third, an unlimited number in turn replace it: the connection is restored and the hypodermic syringe is ready for action again. How the new one is brought into relation with the poison duct has afforded much speculation, and in the American scientific journals, as well as those of Europe, papers on this subject appear from time to time. Dr. Weir Mitchell of Philadelphia affirms that when the fang is lost by natural process it is replaced in a few days: when by violence, several weeks elapse before the next is firmly fixed.[97] He speaks of the rattlesnake chiefly. Fayrer gives the periods in several cobra experiments. In one cobra whose fangs were carefully drawn out on Oct. 7th, new fangs were ‘anchylosed’ to the bone in twenty-four days. In another, thirty-one days elapsed before the new ones were ready for use; and in two others, eighteen days. In all of these cases the new fangs were capable of inflicting deadly injury by the time stated.

But the perfection of mechanism culminates in the viper fangs; and reasoning from analogy, the intensity of poison in their glands also. When at rest, these lie supine along the jaw, but can be ‘erected,’ i.e. sprung down, for use by a special muscle. The two fangs above the dotted illustration of viperine dentition (p. 355) show both positions. Nicholson affirms that the Indian viper Daboia can inject as much poison in half a second as a cobra can in three seconds; ‘that whereas a cobra’s virus flows in small droplets, the viper’s runs in a fine stream.’ Though a much smaller snake than the cobra, Daboia’s fangs are nearly double the size, as may be observed by comparing the figs. C and D (p. 349). There seems reason to believe also that this viper (which in its features Fayrer considers a true Indian type) can inflict injury with more than the pair of functional fangs. ‘In reference to the connection of the poison fangs with the maxillary bones,’ says this learned experimentalist, ‘I would note that second or even third supplementary fangs may be anchylosed with the principal one to the maxillary bone. I have before me the skull of a Daboia, for which I am indebted to Mr. Sceva, in which this is the case; and where there are five well-developed poison fangs on each side, of which on one side two are anchylosed to the bone.’[98] (Described by Mr. Tombes, Phil. Trans. vol. clxvi. p. 146.)

This may explain what we so often read in the description of venomous snakes found with two, three, or more fangs on each side. In my Lachesis two were distinctly visible before I began to dig for those hidden in the loose membrane, of which there seemed an abundance, and I am nearly certain that the second one had its own particular sheath. The spirit in which the specimen had so long been immersed, as well as my awkward probings, forbid me to speak with certainty regarding this second sheath.

After one of his rattlesnake bites—twenty days after—Dr. Stradling informed me by letter: ‘My little durissus is shedding its skin; but when that is over, I shall certainly examine its mouth. Now that my arm is on the verge of ulceration, I find what I had not noticed before, that each puncture is double—two large ones and a tiny second one, about ¹/₁₂ inch behind each, standing out in black relief against the scarlet skin.’

Neither of these experimentalists stated positively that the reserve fangs were in connection with the duct, a phenomenon which I believe is still unexplained. Fayrer removed the functional fangs from an Echis carinata, and observed that there were no others fixed at the time, though there were others loose in the mucous membrane. On the fifth day another pair were anchylosed and ready for use! As will be presently seen, this little viper of sixteen or eighteen inches (almost too small to recognise near the great python in the frontispiece), displays corresponding vigour both in the potency of its venom and in the renewal of its weapons.

From the foregoing illustrations of numerous pointed teeth, the question might arise, ‘How are they disposed of when the mouth is closed? and from the narrow space which is apparent in the flat head of a snake, and the close fit of the jaws, how do the four or six rows meet without interfering with each other?’ This difficulty is obviated by the teeth not closing one upon the other as ours do. Nor are the palate teeth in the centre, or they would wound the upper part of the trachea and the tongue sheath, which occupy considerable space. They close down on each side of these organs. ‘Every relief on one surface fits into a corresponding depression on the other surface, and accurate apposition of every part is obtained,’ Nicholson explains to us. ‘The four upper rows of teeth divide the roof into three parts, and the lower jaw teeth fit between the upper maxillary and palatine teeth.’

There remains yet much more to describe in connection with the poison fang, which might come in the present chapter; but as the two following will treat of the ViperidÆ and the CrotalidÆ—the dentition being the same in both—the viperine fangs shall claim further space under those heads. These three consecutive chapters, and also chap. xxii. on some exceptional forms of dentition, must necessarily be somewhat blended; but I divide them thus in order to present the distinct families more clearly, and render the subject less tedious to the reader.