THE CLASSIFICATION OF CRUSTACEA 37 





dorsal shield, or carapace, covering the greater part of 

 the body, which consists of a large number of seg- 

 ments (about twenty- 

 eight), and ends be- 

 hind in a pair of 

 long antenna-like fila- 

 ments. The fin-like 

 feet are also very nu- 

 merous (about sixty- 

 three pairs). The eyes 

 are not stalked, but 

 are set close together 

 on the upper surface 

 of the carapace. 



The third order of 

 the Branchiopoda, 



the CONCHOSTRACA 



(Fig. n), are not re- 

 presented in Britain, 

 though several 

 species occur on the 

 Continent of Europe. 



T , , FIG. 12 Daphnia pulex, A COMMON 



In these the cara- SPECIES OF "WATER-FLEA." MUCH 



pace forms a bivalved gSde^ 15 



shell, completely en- Female carrying eggs in the brood- 



closing the body and chamber 



limbs, and closely resembling that of a small mollusc. 

 The fourth order, the CLADOCERA, comprises the 

 so-called " Water-fleas," which are abundant every- 



