392 



INVERTEBRATE MORPHOLOGY. 



upon tlie sides of the body and forming a long cylindrical 

 unjointed appendage. 



Respiration is usually effected by the general surface of 

 the body and the inner walls of the shell duplicature, though 

 in certain Cypridinidse a double row of respiratory processes 

 are situated upon the dorsal surface of the body near the 

 second thoracic appendage. The so-called branchial lobes on 

 the maxillse probably subserve the respiratory function only 

 by renewing the water in contact with the body surface. A 



H 

 Pr 



Ai^ 



Fig 176. — Cypridina mediterranea. Female (after Claus). 



At^ — iinteuuule. 

 AP — antenna. 

 A = heart. 

 Mnp = mandibular palp. 

 M^, Ma? = first and second maxilla. 



o = simple eye. 

 Oc = compound eye. 

 Pr = fi-ontal organ. 

 8m = shell-muscle. 

 i', T" = first and second thoracic 

 appendages. 



single median eye alone is present in Gypris and Cytliere, but 

 in addition a pair of lateral compound eyes occurs in Cypri- 

 dina. The frontal sense-organ is a single strong process, in 

 certain forms lying slightly above and between the antennules. 

 A heart is present in Cypridina and Halocypris as a saclike 

 organ with two lateral ostia and is not prolonged into arteries. 

 In Cypris and Oy there it is entirely wanting. 



The Ostracoda occur both in fresh water and in the ocean. 

 The genus Cypris and its allies are for the most part aquatic 

 while the other genera mentioned are exclusively marine. 



