NATURAL HISTORY. 



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Class VII. . . CRUSTACEA. (-Lat. Crusta, a crust or shell.) 



^/ 



Sub-class I. . MALACOSTRACA. ( Gr. MaAa/cof, soft ; uarpai<.ov, a 

 shell.)* 



Order I DECAPODA. (Gr. At'/ca, ten ; Trovg, a foot.) 



Sub-order I. DECAFODA-BBACHYUBA. (Gr. Bpa\'iV, short; ovpu, a tail.) 

 Family I. . . Cancerida?. (Lat, Cancer, a Crab.) 



CANCER. 



Pagurus, the Crab. 



The CRUSTACEA are almost all aquatic animals. They have 

 no internal skeleton, but their body is covered with a strong 

 crust, which serves for protection as well as for strength. 

 Their whole framework consists of a series of rings fitted to, 

 and working in each other ; some forming limbs, and others 

 developing into the frame work supporting the different organs. 

 From this reason, they and the remaining animals, as far as 

 the star-fishes, who have no limbs, are called " articulated" 

 animals. 



* So called because their shell is soft compared with that of the univalve or bivalve 

 molluscs. 



