New Species of Palaeozoic Fossils, 189 



LuciNA (Paraoyclas) elltptica Hall var. occidentalis. 



Shell orbicular, of medium size, nearly circular in outline, with 

 regularly convex valves and small closely appressed and approximate 

 beaks, centrally situated. Cardinal border very slightly excavated 

 just anterior to the beaks, but rounded and full behind. The sinus 

 just within the posterior cardinal margin (so characteristic of the 

 group) is but slightly developed. 



. Surface marked by strong, sharp striae, which are often developed 

 into irregular concentric ridges. 



This species has been usually considered identical with Lucina (P.) 

 proaria of Goldfuss, from the Devonian of the Eilel, but the beaks 

 are less prominent, and the cardinal line less straight on the posterior 

 side and less excavated anteriorly, while the surface is much more 

 strongly marked concentrically. 



The L. (P.) elltptica, as it occurs in the limestones of New York, is 

 usually in the condition of casts of the interior, and the surface mark- 

 ing is rarely seen. They are, moreover, usually vertically com-" 

 pressed and otherwise distorted, appearing sometimes abruptly 

 fusiform. 



The difference in aspect between the specimens from the eastern 

 and western localities is apparently mainly due to the preservation of 

 the shell in the latter. The relative position of the beaks is likewise 

 influenced by the direction and degree of pressure. 



Forination and locality. In the upper limestones, near Louisville, 

 Ky. ; at Charleston Landing and elsewhere on the Indiana side of the 

 Ohio river. From the cabinet of Dr. James Knapp, and from former 

 collections of Major S. S. Lyon. 



Cypkicakdinia inflata var. subequivalvis n. sp. 



Shell small, nearly equivalve, subcylindrical, beaks terminal ; car- 

 dinal and basal margins subparallel ; left valve slightly smaller, less 

 convex, and straighter than the opposite; the post-umbonal slope 

 distinctly angular, while on the right valve it is subangular or 

 rounded. 



Surface marked by about twelve to fourteen or sixteen strong, 

 equal, lamellose, concentric ridges. 



The valves are sometimes so nearly equal in convexity, particu- 

 larly when crushed, that they might be considered as equal ; several 

 good specimens, however, clearly prove the slight inequality charac- 

 terizing the genus. 



This shell resembles C. inflata {Cypricardites inflai^ of Conrad), 

 but the valves are more nearly equal, and the right ralve is less 

 inflated. 



