THE CROTALIDÆ.

IN the several chapters in which the rattlesnake has been introduced, the reader has seen that for about 250 years it has been an object of interest and of study among naturalists, and that first one and then another has made fresh examinations of its various parts, giving to the world new items of information as the results of such observations.

And can there remain anything further to find out about it? we may ask in surprise. Yes, there is. There yet remains to comprehend and decide upon one feature which thus far has defeated conjecture and investigation—the ‘pit’ (p. 277). Possibly among the indefatigable observers in the land of rattlesnakes, recent labours may have been rewarded by some new evidence of the utility of this peculiar orifice, and already their zoological journals may have enlightened ophiologists on its functions. At the present moment I am not aware of such information; and time will not permit of further delay to enable me to send a message of inquiry across the great deep.

Hitherto the pit has certainly plagued not only zoologists, but all classifiers of the Ophidia; because serpents that have this facial depression embrace so many widely differing genera, some of them resembling in all other respects the true vipers, and others the rattlesnakes, so that they have come to be distinguished as the ‘pit vipers.’

One of our most able biologists, A. R. Wallace, in his Geographical Distribution of Animals,[106] informs us that ‘the CrotalidÆ, including the deadly rattlesnakes, abound most in the oriental regions’ (though not a single rattlesnake is found there, or in the Old World at all). Let us seek for the reason of this apparent incongruity, and how it is that a large number of serpents which have no rattle come to be placed among those which have an instrument specially constructed to produce a rattling sound.

Not to weary the reader by attempting to describe the various systems of classification adopted by the many herpetologists who were the contemporaries and immediate successors of LinnÆus, we will rather invite his imagination to picture the geographical history of our globe during that age. Travels, explorations, the establishment of new colonies, and the settlement of new territories marked the era; and, as a sequence, new and hitherto unknown fauna were continually brought home to Europe. We have seen, too, how natural history had been growing into a science, and how travellers and zoologists stimulated each other by their researches and writings. To recall a few of the names with whom reptiles are associated, and to remind the reader that one arranged them according to their scales, another their form, a fourth their teeth, a fifth their habits, and so on, and that even at the present day the classification of them is far from complete, the present writer will be absolved from attempting anything beyond generalization.

Studying snakes towards the end of the last century, were Laurenti, Buffon, Bonnat, LacepÈde, Klein, Seba, etc.

In the early part of the present century were Latreille, Shaw, Daudin, Oppel, Merrem, Wagler, Neuwied, Cuvier, and many others till we come to Gray, Fitzinger, and Dumeril, 1844. This last author, in his introduction to Les serpents solenoglyphes, dit Thanatophides, including the most deadly snakes, devotes several pages to the subject of the ‘pit,’ and why it had especially occupied the attention of those herpetologists who were endeavouring to improve the previously imperfect systems. Wagler in 1824 assigned the name Bothrops (from ?????, any hole, or pit, or hollow dug) to vipers with the pit that had only scales and no plates or shields on their head, separating these from the rattlesnakes and from those that have shields (see illus. p. 318). This nomenclature of Wagler’s did not commend itself to other herpetologists, and Fitzinger, in his Systema Reptilium, 1843, extending the group, retained the name for one of the five families into which he divided all the venomous snakes. Fitzinger’s fifth family, the Bothrophides, included some of the Indian pit vipers; but as some of these latter have shields on their head, they could not be admitted into Wagler’s group with scales only. As the present object is to demonstrate some of the perplexities of naturalists, and to arrive at the reason why so many snakes without the crotalon are called CrotalidÆ, we will quote Dumeril’s reasons, inviting the reader to picture to himself the interest with which new examples were brought home for investigation, and the obstacles presenting themselves to herpetologists, who find one feature claiming alliance to this snake, while another feature points an alliance to an entirely opposite one.

So Dumeril shows us why some of the herpetologists wished to admit every species that has the nasal fosse under the generic name BothrophidÆ, and others would have limited the term to a few, because the name does not suit them all equally well. ‘Beaucoup d’autres serpents presentent aussi des enfoncements creusÉs sur la tÊte et sur le bord des lÈvres.’ These depressions, called by Professor Owen ‘secreting follicles,’ may be easily distinguished on the upper lip of some of the larger constrictors. In the Reticulated python you can count these pits like deep dimples round the mouth. In the Diamond snake (Morelia spilotes) they are remarkably deep along the lower lip.

Of those ‘follicles’ in the CrotalidÆ Dumeril writes: ‘Les fossettes paraissent devoir Être des organes particuliers dont l’usage ou la fonction n’est pas connu il est vraix, mais qui semble avoir quelque importance par leur position constante entre les orifices rÉels des narines et les yeux, at leur structure anatomique assez compliquÉe. À cause de la grande analogie qu’ils ont tous avec les serpents À sonnettes, nous avons prefÉrÉ appeler ceux-ci les crotaliens.’[107]

The above words are under the head of ‘Les Crotaliens,’ a name retained, he had already explained why. ‘Les solenoglyphes qui ont les narines doubles en apparence seront pour nous les Crotaliens quoique cette dÉnomination puisse, À tort, porter À croire que ces espÈces font du bruit avec leur queue: elle indique seulement leur rapports avec les crotales Établis d’aprÈs la prÉsence des fausses narines ou fossettes dont nous venons de parler. On nomme quelquefois ces Ophidiens Bothrops.’[108] ... ‘Comme ce caractÈre conviendrait À tous les Crotaliens parcequ’ils ont tous des fossettes dites lacrymales, ce nom (Bothrops) deviant par consÉquent trop gÉnÉral.’[109]

In retaining Bothrops as a generic distinction, a large number of non-venomous and constricting serpents must have been included, which probably induced Wagler’s opposers to say of him that he ‘created a system in which the venomous and non-venomous were huddled together pell mell.’

Thus we see that on account of the nasal fosse the Indian crotaline snakes could not be true vipers; they could not be exclusively BothrophidÆ, for the reasons given above, and they certainly are not rattlesnakes; but for want of a better name they are ‘CrotalidÆ,’ as they have (minus the rattle) more features in common with rattlesnakes than with any others.

In the slough of a rattlesnake you may see the form of this pit. It is lined with scales, and reversed in sloughing, perfectly shaped as a tiny glove finger.

When Dr. J. E. Gray, F.R.S., etc., edited a short-lived little magazine in 1831 called the Zoological Miscellany, the whole of the known CrotalidÆ consisted of ten genera and thirty species, of which sixteen species belonged to Asia and its adjacent islands, one to South Africa, and the rest to America. When he published his catalogue of snakes belonging to the British Museum in 1849, he enumerated eleven genera and thirty-seven species. Wallace, 1876, gives eleven genera and forty species, the eastern examples of which belong to India, Siam, Java, Borneo, Tartary, Thibet, Japan, and Formosa. Still more recently some belonging to the Western States of America have, I believe, been added by Cope or Coues, the latter informing us that up to the date of his paper, 1878, eighteen species and upwards of the rattlesnake proper had been described in the United States, nearly all in the west and south-west. So, as those vast deserts are being explored, new species are continually discovered.

Of the Indian species of CrotalidÆ, those minus a rattle, Fayrer says that they are chiefly in Malaya and Indo-China. Many of them, the Trimeresuri, are arboreal, and like the foliage in colour. They have the viperine aspect, but are ‘less formidable than their American congeners,’ being of much smaller dimensions. Only one, Halys, has anything approaching to a rudimentary rattle, a tail ending in a spine. Of the Trimeresuri, the tree species, Fayrer affirms that few deaths are ascribed to them. Some attain to above three feet in length. He thinks a feeble person might die of their bite. They are of a sluggish habit, and lie quietly hidden among the leaves of low bushes and ferns. They will even suffer themselves to be moved without attempting to bite, but one that was pressed to the ground with a stick struck so hard as to break both its fangs. They feed chiefly on insects. Their habits are crepuscular if not nocturnal, and Fayrer does not state positively that they or any of the Indian CrotalidÆ are viviparous.

Of the principal American CrotalidÆ that are not true rattlesnakes, the ‘Bushmaster’ (Lachesis mutus) stands first. This is undoubtedly the largest venomous serpent known. In length it equals the Hamadryad; and in thickness, the large African vipers. On looking closely at the illustration of this reptile’s tail (p. 176), it will be seen that in addition to the spine which terminates it, there are several rows of fine, elaborated scales, which under the microscope appear almost as curiously pointed as those on the head of Vipera nasicornis. Dumeril thus describes the tail: ‘PonctuÉe, et prÉcÉdÉe de dix ou douze rangÉes d’Écailles Épineuses, un peu courbÉes en crochets À la pointe.’ This is the snake called Crotalus muet, or ‘dumb rattlesnake,’ by LinnÆus, and which is supposed to simulate the sound of the rattle by vibrating this point against the leaves; but many other snakes do this whether their tail is pointed or not, as we saw in chap. xi. Any small thing, such as a twig rustling among dead leaves, would produce the same sound. The near approach of Lachesis to Crotalus horridus of the same habitat is, however, seen in this rudimentary rattle, the agitation of which may similarly be attributed to the timidity of these ‘highly nervous and irritable creatures,’ to repeat Coues’ words; for deadly as they are, timidity strongly displays itself. Watching the venomous snakes when their food is dropped into their cages, their excessive caution, amounting to cowardice, is remarkable, and this with the rattlesnakes especially. One will fix its eyes on the rat which is running about, and shrink back terrified if it approach too closely. Then if the quadruped is a moment quiet, the snake appears to be considering whether it will be advisable to attack it or not. Stealthily and slowly it approaches its head, but on the slightest movement of the little animal, recedes in alarm, and is some time before it makes a second venture. I have seen a rattlesnake thus timidly advancing and recoiling three or four times before it has the courage to give the fatal stroke. Even after the bite it watches its victim with a steadiness in which terror is the strongest expression; and when the rat has remained motionless for a time, and the rattlesnake ventures near to investigate and make sure it is dead, one faint gasp or dying struggle will cause the reptile to dart back in excessive alarm, and wait again some minutes before venturing near. After long and patient observations, I am still doubtful whether stupidity or timidity predominates in viperine natures.

Of the other well-known and formidable American CrotalidÆ is the ‘Fer de lance’ (Trigonocephalus lanceolatus) of the Antilles and Central America. This has also a pointed tail. The Jararaca of Gray (Craspedocephalus Braziliensis) is another, but without the point. Of the true rattlesnakes, Dumeril gave five genera in 1844, viz. Crotalophorus, Crotalus, Caudisona, Urocrotalon, and Urosophus.

From the two species originally known, we see how they have gradually multiplied as the country has been more thoroughly explored. In 1860, Dr. Weir Mitchel affirmed that twenty species had been then described; probably the most recent ‘Reports’ or Bulletins will tell us of yet others. And these latter are exclusive of the non-rattle-bearing CrotalidÆ.

Dr. Mitchel’s experiments were with the northern species, chiefly Cro. durissus; and as a relief from this wearisome classification, some of his observations will be welcome. One very noteworthy result is that the Crotalus does occasionally produce a sound independently of the rattle. Not a prolonged hiss, or by any means so loud as the innocent snakes, but merely ‘the expiration of air from the lungs just before striking.’ I have never observed or heard this in our London rattlesnakes, but it no doubt is of the same character and degree of sound as that produced by the Cerastes and the little Echis, and which more resembled a short, feeble, spitting sound. Still, as we are informed by Dumeril that rattlesnakes are ‘deprived of voice,’ it is interesting to know that, on the authority of Dr. Weir Mitchel, some slight sound, though not a regular hiss, does sometimes accompany the action of striking.

An inquiry has lately met the eye in one of our scientific journals as to whether a rattlesnake drinks. Dr. Mitchel clears away all doubts on that subject by impressing upon those who keep these creatures the importance of giving them plenty of water, particularly when changing the skin. Deprived of it, the cuticle comes off unhealthily—desquamates, in fact, in bits. At the casting of the cuticle, or previous to the process, they will not only drink, he tells us, but lie for hours in the water. When they were disinclined to eat, and had fasted long enough to endanger their health, he fed them by force with milk and insects, and the way he managed was to get their mouths open and insert a tunnel a safe distance down their throat. While held in this position, a repast consisting of insects and milk was pushed down the tube of the tunnel in sufficient quantities. The most surprising circumstance in connection with this style of feeding, and also with the process adopted by Dr. Shortt of Madras in filling his cobras ‘as full as they could hold’ with sour milk, is that these fastidious and frightened reptiles did not disgorge the diet. Both experimentalists, however, found it answer, reminding us of some advice given to the keeper at the London Ophidarium in the case of the Hamadryad, which, having no snakes to dine off one winter, elected to fast. To force frogs or fish down its throat was suggested; but no one could be found brave enough to undertake the task, and happily ‘Ophio’ survived till a relay of ring snakes arrived.

Both Mitchel and Coues corroborate what has been observed by others regarding the increased virulence of the bite when moulting; but both are of opinion that this is owing to an accumulation of venom, as the snakes have not been feeding or expending their store for some days. Even while not feeding, their venom is secreted all the same, and they survive many months, even a whole year and more, without food. Dumeril mentions one that lived twenty-five months without feeding.

A startling and almost horrifying demonstration of what physiologists would perhaps attribute to nervous or to muscular irritability is described by Dr. Mitchel, namely, an action that had been begun in life, carried out in a headless snake. On p. 281 was described the astonishment of Colonel Beverley, who observed the severed head of a rattlesnake attempting to bite. ‘Then the head gave a sudden champ.’ Long after a snake is dead the tongue will be exserted as in life; and in other actions they, as it were, carry out their intentions though deprived of vitality. ‘The headless trunk will strike,’ says Dr. Mitchel, and continue to do this when touched or irritated as if it still had its head and its fangs to strike with!

Mr. George Catlin in his Life among the Indians relates a circumstance of this kind which may well be introduced here, as illustrative of this amazing fact—a rattlesnake coiling and springing after it is decapitated. His party were going down a river, and had just landed to explore a little, when he saw a large Crotalus, and seizing his gun fired at its head. At the same moment it leaped and sprang towards him, apparently striking him on the breast, Mr. Catlin being on the point of leaping back into the boat. He thought he had fired and missed his aim, and was a dead man, nevertheless much wondering at having missed his mark. Meantime, an Indian, seeing a spot of blood on the front of Mr. Catlin’s linen smock, exclaimed, ‘You are bitten!’ and without ceremony the smock and flannel shirt were torn open, and a spot of blood on his breast was exposed to view. Promptly the blood was washed off, and the Indian on his knees had his mouth at the wound preparing to suck out the poison. Quickly looking up, however, he rose to his feet, and with a smile of exultation said, ‘There’s no harm! You’ll find the snake without its head.’

Stepping ashore again, and pushing aside the long grass, there, sure enough, was the headless rattlesnake, coiled up where it had fallen, and with its headless trunk erect, ready for another spring. Mr. Catlin had not missed fire, but the creature so near the spring, was so ready at the instant with its aim made, that it leapt and struck Mr. Catlin probably on the very spot where it would have bitten him had the sportsman missed his mark. The bleeding trunk had printed its stroke with blood, driving the stain through the dress to the skin. ‘How curious it is,’ Mr. Catlin remarks at the conclusion of his narrative, ‘that if you cut off the head of a rattlesnake, its body will live for hours, and jump at you if you touch it with a stick, when if you break his spine near the tail, with even a feeble blow, it is dead in a minute. This we proved on several occasions.’

Mr. Catlin also helps to confirm what has been already stated in these pages, viz. the certainty of the mate being within hearing of the rattle, and responding when one of them sounds an alarm; also that ‘they can track each other and never lose company, though when met are not always seen together, so that if we kill one over-night and leave its dead body, the other will be found by its side in the morning.’

A near relative of the rattlesnake is the ‘copper-head,’ Trigonocephalus contortrix of the United States, known also as the ‘Red adder,’ and the ‘Dumb rattlesnake.’ It is the Boa contortrix of LinnÆus, who, as we explained above, and also in chap. ii., divided the Ophidia into only three or four families, calling an immense number, both venomous and harmless, ‘boas.’

This member of the CrotalidÆ is said to be as venomous as the rattlesnake, and is much more dreaded, because it has no rattle to give warning of its proximity. When a bitten person survives, the effects of its bite are said to be felt annually, as in the case of the rattlesnake, and the injured limb ‘turns the colour of the snake.’ In regard to this latter symptom, said to show itself in the case of so many snakes, the bitten limb assumes all manner of horrible tints in most cases, and it does not require a great stretch of imagination to detect colours resembling the also many-tinted aggressors. Still there may be more in this than we at present know of.

In the cranberry swamps and tamarack marshes in the northern districts of Ohio formerly were found immense numbers of a small and very dark brown rattlesnake known as the Massasauga. It is seen lying in clusters like small twigs on dry leaves, and still is found in considerable numbers in some remote districts. The illustration of the small rattle (p. 302) was sent me from that neighbourhood, and is, I believe, from a true ‘Massasauga.’ This is the one (as I think I am safe in stating) that was first (1810) described by Dr. Kirtland, a distinguished naturalist of Ohio, and after him named Crotalophorus Kirtlandi. Its range is confined to the swampy districts of Northern Ohio and Southern Michigan. Its rattle being scarcely audible, this little snake gets frequently trodden upon, and persons are as frequently bitten; but Dr. Kirtland stated that he had never known any one to die of its bite, which is scarcely worse than the sting of a hornet. It is a link between the last-named snake, the ‘copper-head,’ and the rattlesnake, having head-shields like the former, and tail of the latter. These small species no doubt help to add to the confusion of evidence regarding the virulence of rattlesnake bites, one person affirming that they are deadly, and another, that recovery is common. The degree of venom between the smallest and the largest of the CrotalidÆ can no more be compared than can the constriction of the little slow-worm round your fingers with the constriction of the anaconda.

A word in conclusion about the rattlesnake’s enemies; and of these hogs come first, next to man. Wild hogs, peccaries, and deer in their native haunts, and doubtless an immense number of snake-eating birds, devour young rattlesnakes. Deer strike them with their hoofs, jumping on them with wonderful adroitness, so as to pin them down with all four feet. Pigs in the west derive no small part of their subsistence from snakes; and, as is now a well-known fact, the introduction of hogs has done more than anything else—not even excepting the annual battue—to diminish the number of rattlesnakes. The venom being ‘innocuous to hogs,’ is a fact only partially stated. A thin hog, bitten on a vein, might die as speedily as any other victim. It is because the venom fails to penetrate the fat, or, as Dr. Coues more ably expresses it, ‘the fluid fails to enter the circulation through the layer of adipose tissue.’ Pigs are not invariably exempt, any more than is the mongoose, from the cobra’s bite. In both cases adroitness assists the animals to evade the strike, and in the latter case the thick fur of the mongoose is as great a protection to it as the fat is to the hog.

Dr. Coues mentions a danger not often anticipated in dealing with rattlesnakes when you wish to examine them. This is their habit of twining themselves around the arm, or wherever they can get hold. ‘Grasp it fearlessly at the back of the neck,’ he says; ‘but even then a large one can constrict enough to paralyze both arms.’ A man who was thus trammelled had to be relieved by a bystander. We are not always prepared for constricting rattlesnakes!