CRUSTACEANS. 183 



CENTIPEDES, OR MYRIAPODS. 



These are very long and worm-like, and divided into 

 very numerous rings or joints, each one of which gen- 

 erally bears two pairs of feet. In the temperate parts 

 of the globe the kinds are not more than two or three 



Fig. 343. American Myriapod, Fig. 344. American Earwig, 



or Galley- Worm. or Lithobius. 



inches long; but tropical species are a foot long in 

 some instances, and the bite of these is often very poi- 

 sonous. All prey upon insects. 



CRUSTACEANS. 



These articulates have a crust or shell, the head and 

 thorax united into one piece, and they live in the 

 water and breathe by means of gills. Some kinds, 

 however, live upon the land. They feed upon all 

 sorts of animal food, and shed and renew their shell 

 many times. 



TEN-FOOTED CRUSTACEANS, OR CRABS, LOB- 

 STERS, AND SHRIMPS. 



Crabs can walk forward, backward, and sidewise. 

 The tail, or hind body, is small, and is doubled under 

 the forward part of the body, where it fits into a groove. 

 The kinds of Crab are very numerous, and some are 

 found on every sea-coast. They vary in size from that 

 of a penny to those which, with the legs outspread, 

 cover a space a yard square. Some kinds are very 



