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THE POPULAR SCIENCE MONTHLY. 



organs by which this is effected are near the muzzle, but, according to 

 Cuvier, they are without the sinuses which exist in the heads of mam- 

 mals. We have tested this sense in several species of snakes, but only 

 pungent odors seem to specially annoy them. The tongue of the ser- 

 pent is a harmless appendage, tough, horny, and double-pointed ; and, 

 like the same member in man, has a wonderful propensity to be in 

 motion. That snakes sting with their tongues is an old but erroneous 

 opinion. Perhaps our own species is not equally innocent in that re- 

 spect. All serpents are carnivorous, and nearly all seize and swallow 

 living food. Their teeth are bony, hard, conical in shape, and exceed- 

 ingly sharp-pointed. None of the class have grinding or cutting teeth. 

 They are formed for holding their food, not to grind, crush, or cut it. 

 Moreover, all their teeth are recurved in form and position ; that is, 

 they point in or backward, so that an object once seized can scarcely 

 escape, and, if the jaws be fully distended, could only with great diffi- 

 culty be ejected. Instances are given where serpents have died from 

 their inability to swallow what they could not eject from their throats, 

 and it is obvious that life could not continue a very long time under 

 such circumstances, for, as Prof. Owen observes, " while swallowing, 

 the tracheae may be so compressed that no air can pass, and their only 

 resource is what is contained in the lungs." 



In the non-venomous species, which includes those that constrict 

 or crush their prey, are found four rows of teeth in the upper jaw and 

 arch of the mouth, and two rows in the under jaw. Venomous spe- 

 cies have usually no more than two rows above, which are on the 

 palatal arch, and two below; but they have on the upper jaw two or 

 more poison-fangs, as shown in Fig. 4, an account of which makes the 

 most fearful chapters in the history of this family of reptiles. 



Fig. 4. 



A. Diagrammatic Section or the Eye 

 of a Viper. 

 a. Eyeball ; &. Optic nerve ; c. Chamber into which tears 

 are poured ; d. Epidermic layer covering the eye. 



B. Head op Viper, showing 

 Poison-Fangs. 



We have observed that serpents swallow their food whole. They 

 make a meal from a mouthful, but the mouthful is sometimes a very 

 large one, for they will swallow animals twice or thrice their own 



