450 NEW GENUS AND SOME NEW SPECIES 



and beautiful species. It is peculiar in its very much com- 

 pressed beaks, and in its greatest diameter being but a short 

 distance above the basal margin. 



5. Symphynota Compressa. Plate XII. fig. 22. 



Testa transversim elongatd, inaquilaterali, valde compressa, ellipticd ; 

 valvulis tenuibus ; natibus sub-prominulis, undulalis ; dente cardinal* 

 prominente ; laterali parvo. 



Shell transversely elongated, inequilateral, compressed, elliptical ; 

 valves thin ; beaks scarcely prominent, undulated ; cardinal tooth promi- 

 nent ; lateral tooth small. 



Hab. 



Ohio. T. G. Lea. 



Norman's Kill, near Albany. Dr Eights. 

 My Cabinet. 

 Cabinet of Prof. Vanuxem. 

 „ Cabinet of Dr Eights. 

 Cabinet of P. H. Nicklin. 

 Cabinet of the Academy of Natural Sciences. 

 Cabinet of the New York Lyceum. 

 Diam. -8, Length 1-7, Breadth 2-8 inches. 



Shell transverse, much compressed, elliptical ; substance of 

 the shell rather thin ; beaks slightly elevated, not decortica- 

 ted, beautifully crowned with small double concentric undu- 

 lations, points of the beaks almost white ; ligament concealed 

 within the valves ; dorsal margin rather elevated posteriorly 

 to the beaks ; posterior margin sub-angular ; posterior basal 

 and basal margins curved ; anterior and anterior dorsal and 

 basal margins rounded ; epidermis olive-green, slightly wrin- 

 kled and glabrous ; radiations over the whole disk ; cardinal 

 tooth prominent and curved, in the left valve with three pro- 

 tuberances, the posterior the highest, sloping to the end of the 

 lateral tooth, the anterior the lowest ; in the right valve one 

 rather large, which closes between the first and second of the 

 left; lateral tooth short and nearly straight, passing from 



