﻿326 CYPROCENIA 



Bapliia hihircthiciua II. and A. AbAMS. Gen. Rec. Moll., II, 



1857. p. 4()(). 

 Margavitatia hildrcthiana 15. II. Wkicht. Check List, 1888. 

 Alasuiodiuita duhia Ficri'ssxc. (aier. Ma^'.. 1835, p. 26. 



AIESOGEN.^. 



Male and female shells alike, short, solid, inflated ; embryos 

 occiipyin,^- a few distinct ovisacs in the center of the outer skills. 



(knus CYPROGKNlA Agassiz, 1852. 



Cyprogcnia Agassiz, Arch, fiir Nat., 1852, p. 47. — Ortmann, 



Ann. Car. Mus., VIII, 1912, p. 312. 



Shell solid, inflated, rounded triangular, sometimes slightly 

 retuse, generally a little biangular behind ; posterior ridge un- 

 usually well developed, especially in the young shell ; unbonal 

 region Hattened parallel with the axis of the shell, sometimes 

 compressed ; Ijeaks curved inward and forward, their sculp- 

 ture very faint, consisting of slightly doubly-loo])ed ridges ; 

 sculpture of the shell nodular, radiately wrinkled or lachry- 

 mose ; ligament black and conspicuous ; lunule distinct and well 

 devcio])ed ; epidermis shining, painted with a delicate, dark 

 mottling on a light ground ; hinge plate wide and flat ; pseudo- 

 cardinals heavy, triangular, blunt and ragged ; laterals short, 

 obliquelv striated; cavity of the beaks not deep; adductor 

 scars small, well impressed, those at the posterior round ; 

 nacre bright and silvery. Animal having the inner gills partly 

 free from the abdominal sac, rounded below ; outer gills 

 smaller ; marsupium consisting of from seven to twenty-three 

 very long, purple ovisacs pendent from near the central base 

 of the outer gills and fonned into a close coil with the ends 

 turne<l inwardly ; branchial opening large, with many small 

 pajiilla; : anal opening smooth. 



Tvpe, Unio irroratits Lea. 



Cyprogema irrorata (Lea) 



Shell suborbicular or rounded triangular, very solid, in- 

 flated; beaks high and full but flattene<l. central or a little 



