226 ^poLoGf. 



larger species, inhabiting warm climates : they are viviparous, 

 and change their skins in the manner of Spiders. 



10. Cancer. Crab. Legs eight, sometimes six or ten ; 

 besides two chelated hands; eyes two, distant, gene- 

 rally pedunculated, elongated, and moveable; tail 

 jointed, unarmed* 



This genus is divided into Crabs, having a roundish flatt- 

 ened body : Lobsters, vrith the body elongated ; tail move- 

 able ; chelate claws, two, flattened, furnished with a move- 

 able thumb -• Cray-Fish, with an elongated spinous body, 

 tail moveable, chelate claws four-sided. These animals feed 

 on all kinds of animal substances either fresh or putrid ; they 

 annually change their shells. 



11. Monoculus. ieg"* four or eight, very long, fprmed for 

 swimming ; body covered by a crustaceous tegument ; 

 eyes in most species approximated, and imbedded in 

 the shell. 



Most of this genus are small aquatic insects, scarcely dis- 

 coverable but with the microscope, some few are large, and 

 the largest of the Insect tribe, is found in this genus, the M. 

 Polyphemus, which has been known to measure two feet in 

 length, exclusive of the tail ; in those species, said to possess 

 only one eye, (from whence the generic name,) the two eyes 

 are so approximated, as to appear single. Food as the last. 



12. Oniscus. Wood-Louse. Jak)* truncate ; antennce seta- 

 ceous 5 bodif oval ; legs fourteen. 



