HOW ANIMALS EAT 



265 



are developed into pouches in which the food may be 

 carried. These may be lined with hair. The tongue is 

 remarkably long in the ant-eater and giraffe, and almost 

 immovable in the gnawers, elephants, and whales. 



3. The Teeth of Animals. Nearly all animals have 

 certain hard parts within the mouth for the prehension 

 or trituration of 

 solid food. If 

 these are want- 

 ing, the legs are 

 of ten armed with 

 spines, or pin- 

 cers, to serve 

 the same pur- 

 pose, as in the 

 horseshoe crab; 

 or the stomach 

 is lined with 

 "gastric teeth," as in some marine snails; or the defi- 

 ciency is supplied by a muscular gizzard, as in birds, 



ant - eaters, and 

 some insects. 

 Even the lobster 

 and crab, in ad- 

 dition to their 

 complicated oral 



FIG. 226. Sea Urchin bisected, showing masticating 

 apparatus. 



B 



FIG. 227. -Teeth and Masticatory Apparatus of Gastro- Organs, haVC the 



pods, enlarged: A, portion of odontophore, or " tongue," stomach fUT- 

 of Velutina, enlarged; B, portion of odontophore of 



Whelk (Buccinum undatunt), magnified the entire nished With 3. 



tongue has too rows of teeth; C, head and odontophore r i' f 



ofUmpettPattttavufeata); D, portion of same, greatly pOWeriUl. SCt OI 

 magnified, to show the transverse rows of siliceous teeth. 



The sea urchin is one of the lowest animals which 

 exibits anything like a dental apparatus. Five calcare- 

 ous teeth, having a wedge-shaped apex, each set in a 

 triangular pyramid, or "jaw," are moved upon each 



