222 THE LIFE OF CRUSTACEA 



in by the small brood-plates. The mouth parts form 

 a short piercing beak with which the parasite sucks 

 the blood of its host. On the under-side of the 

 abdomen may usually be found the minute male, 

 attached, like a secondary parasite, to the body of 

 the female. 



The species of Epicaridea are very numerous, and 

 they infest Crustacea belonging to nearly all the 



FIG. 71 A, FRONT PART OF BODY OF A PRAWN (Spirontocaris 

 polaris), FROM ABOVE, SHOWING ON THE RIGHT SIDE A SWELLING 

 OF THE CARAPACE CAUSED BY THE PRESENCE OF THE PARASITE 

 Bopyroides hippolytes IN THE GILL CHAMBER ; B, THE FEMALE 

 PARASITE EXTRACTED AND FURTHER ENLARGED ; C, THE MALE 

 PARASITE ON SAME SCALE AS THE FEMALE. (After Sars.) 



chief groups of the class, a few even being parasitic 

 on other Epicaridea. Many of them differ greatly 

 from the Bopyrus just described, and in some cases 

 it would be impossible to guess from the structure of 

 the adult animals that they were Isopoda, or even 

 Crustacea at all. The life-history is not yet com- 



