254 COMPARATIVE ZOOLOGY 



The first six pairs of legs in the lobster and crab are 

 likewise appropriated to conveying food into the mouth, 

 the sixth being enormously developed, and furnished 

 with powerful pincers. Scorpions have a similar pair 



of claws for prehension, and 

 also a pair of small forceps 

 for holding the food in con- 

 tact with the mouth. In 

 their relatives, the spiders, 

 the claws* are wanting, and 

 . the forceps end in a fang, 



* IG. 216. One of the Fangs, or Perforated r ' 



Mandibles, of the Spider, much magni- Or hook, which is perforated 

 fied. 7A 



to convey venom.' 4 



The biting insects, as beetles and locusts, have two 

 pairs of horny jaws, which open sidewise, one above and 

 the other below the oral orifice. The upper pair are 

 called mandibles ; the lower, maxillae. The former are 

 armed with sharp teeth, or with cutting edges, and 

 sometimes are fitted, like the molars of quadrupeds, to 

 grind the food. The maxillae are usually composed of 

 several parts, some of which serve to hold the food, 

 or to help in dividing it, while others (palpi) are both 

 sensory and prehensile. There, is generally present a 

 third pair of jaws the labium which are united in 

 the middle line, and serve as a lower lip. They also 

 bear palpi. The mantis seizes its prey with its long 

 fore legs, crushes it between its thighs, which are armed 

 with spines, and then delivers it up to the jaws for 

 mastication. All arthropods move their jaws horizon- 

 tally. 



The backboned animals generally apprehend food by 

 means of their jaws, of which there are two, moving 

 vertically. The toothless sturgeon draws in its prey by 

 powerful suction. The hagfish has a single tooth, which 

 it plunges into the sides of its victim, and, thus securing 



