102 



NUTRITION. 



(Echinus,) this apparatus, which has been called Aristotle's 



Fig. 5G. 



lantern, (Fig. 56,) consists of numerous pieces, and is much 

 more complicated. Still, the five fundamental pieces or jaws, 

 each of them bearing a tooth at its point, may be recognized, 

 as in Scutella; only instead of being placed horizontally, 

 they form an inverted pyramid. 



213. Among the Mollusks, a few, like the cuttle-fishes, 

 have solid jaws or beaks closely resembling 

 the beak of a parrot, (Fig. 

 57,) which move up and 

 down as in birds. But a 

 much larger number rasp 

 their food by means of a flat 

 Fis;. 57. blade coiled up like a watch- 



spring, the surface of which is covered with innumerable 

 minute tooth-like points of a horny consistence, as seen in a 

 highly magnified portion of the so-called tongue of Natica, 

 (Fig. 58, a,) which, however, is 4ftly a modification of the 

 beaks of cuttle-fishes. 



214. The Articulata are remarkable, ag 

 a class, for the diversity and complication 

 of their a-- paratus for taking and dividing 

 their food. In some marine worms. Nereis 

 for exarr pie, the jaws consist of a pair of 

 curved, horny instruments, lodged in a 

 sheath, fFig. 59.) In spiders, these jaws are external, and 



Fig. 58. 



'■^vv{..^-0 



Ux..l 



