106 Cincinnati Society of Natural History. 



some doubt and hesitation that we have ventured upon proposing a 

 new generic appellation. 



Angellum cuneatdm, u. sp. (Plate III., fig. 11.) 



['Ety .—Cuneatws, wedge-shaped.] 



Shell medium size, equivalve, much elongated from the cardinal line 

 to the base, middle part sub-cylindrical, where width and depth are 

 sub-equal; lower half wedge- shaped ; umbones high, angular, and 

 prominent anteriorl}^; beaks acuminate and incurved over the cardinal 

 line; hinge line straight, short, and nearly at right angles to the longer 

 axis of the valves. The cast is a little convex on the anterior side, 

 where there is some evidence of a bj'ssus, and slightl}- winged on the 

 posterior margin. Surface marked by concentric lines. 



The specimen illustrated I collected in the upper part of the Cincin- 

 nati Group, at Richmond, Indiana. 



Cythere irregularis, n. sp. [Plate III., fig. 7, dorsal view; fig. 7a, 

 side view, ventral margin uppermost.] 



[Ety. — Irregularis, irregular.] 



Valves smooth, or minutely granular, highly convex anteriorl}^, and 

 rapidly declining to the posterior end. Ventral margin forming a 

 broad curve. Dorsal margin slightly depressed at the sulci in the 

 valves. Deep sulcus in the middle of each valve extending from the 

 dorsal margin halfway across the valve. Small sulcus near the pos- 

 terior end of each valve extending about half way across the middle 

 part of the valve. 



Ant^-ior end of the shell subreniform. Posterior end rounded and 

 wedge-shaped- Narrow border all around the margins of the valves. 

 No visible eye-tubercle. 



Length of a large specimen, 0.17 inch; height, 0.10 inch; convexity. 

 0.10 inch. 



This species is distinguished by its subreniform anterior end, wedge- 

 shaped posterior, and deep central sulci. 



The honor of first collecting and calling attention to this peculiar 

 form belongs to Mr. George L. Vallandigham, who found it near the 

 top of the hills at Cincinnati, associated Avith Cythere cincinnatiensis. 

 He collected several specimens, and presented them to the author for 

 illustration and description. 



LiCHAs iiARUisi, n. sp. (Plate III., fig. 9.) 

 The specimen illustrated shows the under side of the pygidium 



