150 IWEr.TEl'.liATE ANIMALS. 



these are nmch smaller than the females, ami (jiiite dilferent from 

 them ill apjieaiauce, and they spend their existeiiee within the shell 

 vf the female. 



Greatly as the (_'irri2)edes are nietamorplio.sed, when compared 

 with the typical Crustaceans, they are not so entirely altered as are 

 the nearly allied animals kmiwn as the Ji/il,:niyjth<iki. These sin- 

 gular Cnistaceans are ti.-ceil pai'asitically to the under side of the 

 abilomen of eralis ami liermit-cralis, the body being a mere muscular 

 sac, with no indications of limbs or of segmentation, attached to its 

 host l>y means cif branched I'oot-like processes of attachment, which 

 sink deei>ly into the tissues of the latter. The 3'onng of these 

 degraded Crustaceans have, however, lindjs ami organs of vision, 

 anil swim about actively in the water. 



