On a second occasion I made a dental examination of the living Xenodon in order to be fully convinced of the nature of its back teeth, and in both instances the fangs were depressed until the snake was provoked into displaying them. It exhibited no spitefulness or attempt to bite, and in both cases folded back its fangs the moment my finger was removed, as if glad that the ceremony was over.
Heterodon d’Orbignyi, being a small and delicate snake, was not again enticed to exhibit its jaws; but my forbearance was otherwise rewarded. One day it was dining off a rather large frog, and its mouth, close to the glass, was stretched open to its fullest extent. The frog had disappeared so far as to be within the mouth, wedging it wide open; and I then saw a fang well erected and in use, moving, being detached, in fact, from the food. It appeared to be somewhat nearer to the front than Xenodon’s fangs, with perhaps only three or four simple teeth before it. But that it was a sheathed fang and mobile I have no doubt whatever, having seen it very distinctly. I told Tyrrell at the time that Heterodon’s fangs were also moveable; but now for the first time I impart this new secret to the public. Xenodon also greedily seizes upon inconveniently large frogs, but it has never displayed its fangs to me while feeding, as the pretty little Heterodon did. One more singular thing did this little Heterodon, and that was to assist itself by coiling its body round an unmanageable frog one day. It did not regularly constrict it in order to kill it; but when caught in the mouth, it helped itself to restrain the straggling limbs by a few coils. Dr. Wucherer affirms that he had never seen its congeners Liophis or Xenodon squeeze or coil themselves round their prey, but Heterodon d’Orbignyi certainly does.
Another peculiarity of the American Heterodons is that of flattening their heads and the upper part of the body when angry or molested. It is this, together with their pseudo-fangs, that have procured them the name of ‘spread-head,’ ‘spreading-adder’, ‘puffing-adder’ or ‘blowing viper’,—because at the same time they hiss violently,—or simply ‘the adder,’ and ‘blausser,’ or the blower.
There are several species of them, all, with the exception of H. d’Orbignyi, having undeniably ugly, viperish-looking heads, ‘Anguis capitæ viperino,’ or ‘Serpent à la tête de vipère.’ The snout terminates in a large, conspicuous, recurved scale which gives them a pug-nosed or rather a hog-nosed appearance. Catesby, who was the first to describe the ‘hog-nosed snake,’ said ‘it hath a visage terrible and ugly.’ In H. niger and H. platirhinos this is most apparent. They belong mostly to the New World, both north and south. One in Virginia is called, from its bright markings, the ‘calico snake,’ the word calico in America being applied chiefly to coloured prints used for dresses. Another is called ‘the mountain moccasin,’ the latter name in the United States being applied to venomous kinds.
In the flattening of the head and body, Xenodon and Heterodon approach the cobras; in the strange dentition they approach the vipers; in their true nature they are harmless colubers: thus do we see the wonderful links or gradations between opposite families, which have been such a perplexity to the early naturalist.
The Heterodons have the reputation of ‘feigning death’ when annoyed. This peculiarity has been commented on by many who have experimented upon the snake for this purpose. Holbrooke observed it in H. platirhinos, and came to the conclusion that it was done at will. ‘It will deceive its tormentor by feigning death, remaining flat and motionless.’ It otherwise ‘flattens the head and upper part of the neck, which it lifts and waves, hissing loudly.’ This is the true cobra manner. He often worried it and tried to make it bite, when it only projected its head in that menacing way, but with closed mouth. On the contrary, other experimentalists describe it with widely expanded jaws when thus annoyed. In an excellent American magazine, Science News, the Heterodons formed the subject of several papers a few years ago. To my friend, Mr. J. E. Harting, I am indebted for some numbers of Science News, in which Heterodons’ performances are fully described. One, on being intercepted in its retreat, ‘threw its head back with widely expanded jaws; but instead of striking, it turned completely over on its back, remaining stiff and motionless, with jaws fixed in rigid expansion, feigning death.’ Reptilian intellect was, however, insufficient to carry out the feint, inasmuch as its full muscular power was exercised to maintain its position. ‘On concealing myself,’ continues the narrator, ‘it cautiously righted itself and made off; but only to repeat the ruse when again caught.’[115] Dr. J. Schneck, in the March number for the same year, describes a similar action on his worrying them with a switch, when, after making futile efforts to attack, they would seem to bite themselves (which they really never do), and then turn on their backs as if dead. After a few moments of quiet they would turn over and beat a hasty retreat. Several other writers in Science News confirm Holbrooke’s experience, that ‘under no provocation can it be induced to bite.’ Those we have seen at the Gardens verify this; exhibiting an extremely inoffensive nature, though no death-feigning or summersault performances. And I am more inclined to attribute the rigidity to a sort of paralyzed terror than to any pretence of being dead. The same thing is observed in some insects. If you blow on them or alarm them, they will flatten themselves against whatever they may be crawling on, and cling close and stiff as if dead, but presently escape. Some other snakes, also, as well as the Heterodons, keep rigidly still as if paralyzed when molested, previous to attempting any escape, though I do not remember any others that turn over on their backs in so singular a fashion.
A few more words about the Deirodon with its still stranger teeth must come in the next chapter.
