. British reptiles and batrachians. Amphibians; Reptiles. 30 REPTILES AND BATRACHIANS. But the chief characteristic of the viper is its poison tooth. "The perfection of mechanism culminates in the viperine fang," writes Dr. Edward Nicholson, a distinguished ophiologist. And by mechanism he refers to its mobility, the action of it. Among the various wonders which we discover in the structure of a snake and its control over parts of its frame that are stationary in other creatures, the power in the viper to raise and fold back its fangs is perhaps the greatest. Vipers, it will be remem
. British reptiles and batrachians. Amphibians; Reptiles. 30 REPTILES AND BATRACHIANS. But the chief characteristic of the viper is its poison tooth. "The perfection of mechanism culminates in the viperine fang," writes Dr. Edward Nicholson, a distinguished ophiologist. And by mechanism he refers to its mobility, the action of it. Among the various wonders which we discover in the structure of a snake and its control over parts of its frame that are stationary in other creatures, the power in the viper to raise and fold back its fangs is perhaps the greatest. Vipers, it will be remembered, have only one tooth, the fang, in each upper jaw, and this when at rest lies back along the gum (as in a, fig. 12), and when in use is " erected," that is, brought down ready to inflict the bite (as in b), and the action is instantaneous, rapid as is that of the viper in striking its victim. The fang is curved, pointed as a fine needle, and " hollow," commonly so called. Strictly speaking, a snake's fang is a long finely pointed tooth, flattened out and rolled over to form a groove, as seen in the magnified examples (fig. r3). In the viper the " join "—as we will call it—is so complete as to be scarcely percepti- ble, in other snakes the fold is more or ing a channel down which the venom ger example, a, the groove is more At the base the venom enters from a Close to the point in a viper's fang and through this slit the venom is forced out again into the wound by the action of " striking," as the rapid bite is called. All is swift as a flash ; but the noxious power of the venom is so great that in that moment of time enough has passed through the tiny slit into the flesh of the bitten creature to cause its death. The viper then draws back its head, and waits till the victim ceases to struggle, when it again approaches stealthily, cautiously surveys the prey, and if quite dead grasps it conveniently, and proceeds to swallow it. I
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