44 PROCEEDINGS OF THE ACADEMY OP [1879. 



Dorsal side of ventral valve sub-semicircular, markings of 

 growth indistinct, parallel to sub-semicircular opening; dorsal 

 side of opening almost perpendicular to hinge line, or about one : 

 tenth inch nearer to the apex. 



Cardinal process or tooth central, round and smooth along its 

 summit, three-tenths inch in length, three-tenths in width, gradu- 

 ally narrowing from the hinge backward, extending from the 

 hinge line to the inner end of cavity. 



The characters which separate this species from G. Tennes- 

 seensis, Roemer, and G. sandalinae, Lamarck, are well marked. 

 The semicircular margin of the mouth in G. Tennesseensis is 

 one-half inch from the apex; while in G. corniculum it is nine- 

 tenths inch, or almost over the hinge line. 



Position and Locality. A few good ventral valves have been 

 obtained from the ferruginous clay, Niagara period, one mile east 

 of Louisville, north side of Beargrass Creek. 



Calceola Coxii, 1 V. W. Lyon, n. sp. 



Shell thick, triangular, valves not articulated ; ventral valve 

 pyramidal ; area large, flat, triangular, nine-tenths inch high, with 

 an obscure central line; markings of growth prominent, extend- 

 ing around the shell parallel to hinge ; hinge line straight crenu- 

 lated, four-tenths inch long. 



Mouth semicircular; cavity three-tenths inch deep ; all around 

 the mouth, extending centrally towards the bottom of cavity, are 

 linear rows of punctures, not so conspicuous as in those of the 

 European species, G. sandalina. The cardinal process central, 

 prominent, short, round, and smooth along its summit. 



Dorsal valve raised slightly, sub-centrally toward hinge line; 

 valve composed of several thin semicircular plates, one above 

 another, gradually increasing in diameter from top to bottom ; 

 area very narrow. Cardinal process not seen. 



In some adult species young are seen attached to the bottom of 

 cavity; none have been found on the outside of shell, as in G 

 attenuatus. 



Position and Locality In same beds as the preceding, also in 



into two right-angle triangles. The hinge is at right angles to the apex ; 

 while in G. corniculum the hinge is at an obtuse angle. 



1 I take great pleasure in dedicating this elegant Calceola to Prof. E. T. 

 Cox, State Geologist of Indiana. 



