CRUSTACEA 



369 



are without opening in the adult. Other glands may be excretory. 

 The NaupliuSy if present, has a bivalve shell. There are among the 

 ostracods freshwater and marine, pelagic and bottom-living forms. 

 Parthenogenesis is common among them, and in some males have 

 never been found. 



fh.1 



-ram. 



Fig. 247. A female of Leptodora kindti. After Lilljeborg. an.' antennule; 

 an." antenna; car. carapace; mdg. mid gut; ov. ovary; ram. ramus of caudal 

 fork; tel. telson; th.i, first thoracic limb; trk.g, ninth trunk somite. 



Cypris (Fig. 248) is a common British freshwater genus. It swims 

 well, by means of its antennae, but i& not pelagic. It is omnivorous, 

 feeding on algae, small animals, detritus, etc., and taking its food in 

 various ways. Large objects are pushed into the shell by the antennae 

 or pulled in by the mandibles, finer particles drawn in by the action of 

 the epipodites of the maxillules (whose fan of setae is conspicuous in 

 the figure), gathered by long bristles on the palps of the mandibles, 



