232 



BIOLOGICAL SURVEY OF 



CusHMANiDEA Blake gen. nov. 



This genus is distinguished from Cytheridea chiefly by the 

 structure of the hinge, and from all of its subfamily by cer- 

 tain rather remarkable features of the appendages. 



The general structure of the shell is that of a Cytheridea, 

 but the hinge is composed of thin, overlapping flanges, not 









Fig. 39 Limnocythere reticulata, male. A. dorsal view. 

 C. detail of shell sculpture. D. genitalia. 



B. right lateral view. 



rows of small teeth fitting into sockets. We may consider 

 these flanges as three pairs. The anterior one is the longest, 

 comprising half the length of the hinge, and the left flange 

 here overlaps the right. The center pair is one-fourth the 

 length of the hinge and the left member underlies the less 

 conspicuous right member. The posterior pair has the same 

 mutual relations as the anterior pair. The great length and 



