OF THE ANIMAL FRAMK. 



m 



the poisonous serpents are raised or depressed at pleasure. The teeth of 

 the xiphias Gladius^ or sword-fish, are similarly inserted ; while his long 

 sword-Hke snout is armed externally, and on each side, with a taper row 

 of sharp, strong, pointed spines or hooks, which are sometimes called his 

 teeth, and which give rise to his popular name. 



The ant-eater and manis swallow their aliment whole : and in many ani- 

 mals the jaws themselves perform the office of teeth, at least with the as- 

 sistance of the tongue. In birds this is generally the case, sometimes in 

 insects, whose jaws are for this purpose serrated or denticulated at the edge, 

 and frequently in molluscous worms. The jaws of the triton genus act 

 like the blades of a pair of scissors. The snail and slug have only a single 

 jaw, semilunar in its form, and denticulated : but the mouth of the nereis 

 has several bony pieces. The sea-rnouse (aphrodita aculeata) has its 

 teeth, which are four, fixed upon its proboscis, and is of course able to ex- 

 tend and retract them at pleasure ; and the leech has three pointed cartila- 

 ginous teeth, which it is able to employ in the same way, and by means of 

 which it draws blood freely. In like manner, though insects chiefly depend 

 upon a serrated jaw, yet many of them are also possessed of very powerful 

 fangs, of which we have a striking mstance in the aranea avicularia^ or 

 bird-spider, an inhabitant of South America, found among trees, and a 

 devourer of other insects and even small birds. It is of so enormous a size 

 that its fangs are equal to the talons of a hawk ; and its eyes, which are 

 eight in number, arranged as a smaller square in the middle of a larger, 

 are capable of being set in the manner of lenses, and used as microscopes. 



In many animals, especially the herbivorous, the tongue itself is armed 

 with a serrated apparatus, the papillae being pointed and recurvated, and 

 enabhng them to tear up the grass with much greater facility. In the cat- 

 kind the tongue is covered with sharp and strong prickles, which enable 

 the animal to take a strong hold ; and similar processes are met with in the 

 bat and the opossum. In the lamprey and myxine families, the tongue it- 

 self is covered with teeth. In that grotesque and monstrous bird the tou- 

 can, whose bill is nearly as large as its whole body, the tongue is lined with 

 a bundle of feathers, of the use of which, however, we are totally ignorant, 

 though it is probably an organ of taste. 



In the crab and lobster tribes the teeth are placed in the stomach, the 

 whole of which is a very singular organ. It is formed on a bony appara- 

 tus, and hence does not collapse when empty. The teeth are inserted into 

 it round its lower aperture or pylorus : their surface is extremely hard, and 

 their margin serrated or denticulated, so that nothing can pass through the 

 opening without being perfectly comminuted. The bones and teeth are 

 moved by pecuhar muscles. It is a curious fact, that at the time the ani- 

 mal throws off its shell, it also disgorges its bony stomach and secretes a 

 new one. 



The teeth of the cuttle-fish are arranged not very diflferently, being situ- 

 ated in the centre of the lower part of the body ; they are two in number, 

 and horny, and in their figure exactly resemble the bill of a parrot. 



The teeth of the echinus genus (sea-hedge-hog) are of a very singular, 

 arrangement. A round opening is left in the centre of the shell for the 

 entrance of the food : a bony structure, in which five teeth are inserted, 

 fills up this aperture ; and as those parts are rnoveable by numerous mus- 

 cles, they form a very complete organ of mastication. 



Such is the variety which the hand of nature, sometimes, perhaps, spor- 



16 



