HOW ANIMALS EAT 



253 



a pair of hard mandibles, resembling the beak of a 

 parrot, and working vertically ; and around the mouth 

 are eight or ten powerful arms 

 furnished with numerous cup- 

 like suckers. So perfect is the 

 adhesion of these suckers, that 

 it is easier to tear away a limb 

 than to detach it from its hold. 

 The earthworm swallows 

 earth containing particles of 

 decaying vegetable matter, 

 which it secures with its lips, 

 the upper one being prolonged. 

 Other worms (as Nereis) are 

 so constructed that the gullet, 

 which is frequently armed with 

 teeth and forceps, can be pro- 



FIG. 214. Suckers on the Tentacles 



truded to form a proboscis for O f a Cuttlefish: , hoiiow axis of 

 seizing prey. the arm ' containing nerve and ar ' 



The Arthropoda exhibit a 

 great variety of means for pro- 

 curing nourishment, in addi- 

 tion to the suctorial contrivances already mentioned, the 

 innumerable modifications of the mouth corresponding 

 to the diversity of food. Mille- 

 pedes, caterpillars, and grubs 

 have a pair of horny jaws moving 

 horizontally. The centipede has 

 a second pair of jaws, which are 

 really modified feet, terminated 

 by curved fangs containing a 

 , poison duct. The horseshoe crab 



FIG. 215. Nereis head, with * 



extended proboscis: ?, jaws; US6S its feet for prehension, aild 

 T, tentacles; H, head ; , eyes. - , . , . , . . . . 



the thighs, or basal joints of its 

 legs, to masticate the food and force it into the stomach. 



tery; c, cellular tissue; d, radiat- 

 ing fibers; h, raised margin of the 

 disk around the aperture f, g, which 

 contains a retractile membrane, or 

 " piston," i. 



