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Western Hog-nosed Snake — Part 2
The majority of these snakes are but mildly poisonous and consequently not dangerous to man in the effects of their bites. Moreover, if biting in self-defence, they do not generally employ their fangs as it is difficult for them to produce a wound with the venom-conducting teeth unless they take deliberate hold and advance the jaws in the familiar, chewing motion of snakes, thus bringing the grooved teeth into a position to be imbedded. Few snakes, unless grasped by the body, will use their jaws in this fashion. If cornered, they simply "strike." As the Opisthoglyph snakes are timid and active, accidents from them are very rare. However, persons have been bitten by these snakes, yet escaped being wounded by the fangs. Such observers have emphatically asserted that such snakes are innocuous and have thus set down their views in literature. There has consequently arisen a tangled argument about these creatures.
An examination of the teeth and a dissection of the head will remove all doubt as to the poisonous character of any of the species. The venom apparatus is, in fact, fully as perfect--though rather in miniature--as that of the much dreaded viperine snakes, but in place of the fangs being perforated and ejecting their venom from an orifice at the tip, they are grooved from the base to the tip. The accompanying figures, illustrating the structure of the fangs of various snakes, demonstrate the quite different dentition of these serpents from the better-known poisonous reptiles.
Though the writer has stated that most of the species occurring in North America are not liable to produce injuries actually formidable to man, wounds from the fangs of snakes belonging to the genera Sibon or Trimorphodon, would likely be followed by marked local symptoms.
The poison of the Opisthoglyph snakes appears to exert a powerful, benumbing influence upon the prey, which, when seized, is worked quickly backward into the mouth by alternate, grasping movements of the jaws, until the fangs are firmly imbedded, and in this position it is held until all struggles have ceased, when it is swallowed. The prey is generally benumbed and helpless within one or two minute's time. After a period of about five minutes it appears to be quite dead. The bitten creature seems to die with the muscles perfectly relaxed and in this condition is easily swallowed by the snake as the limbs fold readily against the body during the progress of the snake's jaws over it. To observe one of these snakes feeding is to appreciate the existence of an excellent development for the overpowering of the reptile's prey.
Though it has not hitherto been the custom, the writer without hesitation classes the Opisthoglypha among the poisonous snakes, and would advise the student to discriminate between living examples of these reptiles and the wholly innocuous snakes they so closely resemble.
An outline of the North American genera follows: (The species of all the genera have smooth scales.)
I. Pupil elliptical.
Size moderate.
Body rather slender; head flat, wide and very distinct from the neck.
Two loreal plates. Trimorphodon.
Conformation and colouration similar to preceding genus.
One loreal plate. Sibon.
II. Pupil round.
Size small.
Body moderately slender. Head but slightly distinct.
Pattern (of local species) in bands extending lengthwise.
Erythrolamprus.