AMERICAN JOURNAL 



DESCRIPTIONS OF NEW GENERA AND SPECIES OP 

 FOSSIL SHELLS. 



BY T. A. CONRAD. 



ANOMIID^. 

 PARANOMIA, Conrad. 



Description. — Irregular, inequivalve, one valve flattened or 

 slightly concave ; hinge of lower valve with a broad irregular 

 triangular tooth or plate, flattened or slightly convex, with sharp 

 margins and an anterior compressed small but prominent tooth ; 

 muscular impression situated towards the ventral margin in a 

 line with the apex or nearly equidistant from the anterior and 

 posterior ends. 



Type Placunanomia Saffordi, Conrad. — Journ. Acad. Nat. 

 Sciences, Vol. IV., p. 290, pi. 46, fig. 21. 



This Cretaceous genus somewhat resembles PUcatula, but 

 it is probably more nearly allied to Placuna. It does not 

 appear to have a foramen, as I supposed, but the shell is very 

 thin about the umbo, and frequently appears from within as if 

 there were a large opening, but this is owing to the disintegra- 

 tion of the shell. It is probable that the young shell had a fora- 

 men, which it lost in a later stage of growth, like Carolia. It is 

 often attached by the umbo to other shells. The genus is very 

 distinct from Placunanomia. 



Two other species are known in the Ripley Group, to which 

 this genus appears to be limited, viz., P. lineata, Conrad, and 

 P. (Placuna.) scabra, Morton. 



NUCULANIDiE. 



YOLDIA, Morch. 



Y. ALBARTA, Conrad, {Y. protexta^ Co7i.,) — Amer. Jour, of 

 Conch., Vol. I., p. 213, pi. 21, fig. 2. 



This shell coming into the same genus with Leda protexta, 

 Gabb, it is necessary to change the name. 



