488 University of Kansas Geological Survey. 



Inoceramus pennatus, n. sp. Plate cxviii, fig. 2; cxx, 2. 



Description : Shell (right and left valves) oblong ovate, mod- 

 erately thin, slightly convex, greatest convexity in central re- 

 gion ; hinge long (sixty mm.) , thicker than shell body ; marked 

 with transverse grooves two mm. in breadth, upper border of 

 grooves bent inward ; grooves marked with striations running 

 parallel and transverse to the groove ; hinge raised and curved 

 inward. Interior of shell smooth, showing no marks or undu- 

 lations ; exterior covered with adhering forms of Ostrea congesta. 



Length of longer diameter, 150 mm. ; height, 75 mm. ; great- 

 est convexity not more than 10 mm. Type specimen is imbed- 

 ded in a matrix of chalk, having valves spread out and open, 

 somewhat resembling wings. Both valves taken together some- 

 what resembling a leaf in general outline, the hinge correspond- 

 ing to the midrib and stem. 



In general form, Inoceramus pennatus does not resemble any 

 of the other species belonging to this genus. In thickness of 

 test it resembles Inoceramus deformis, but differs from that spe- 

 cies materially in other respects, as will be seen by a comparison 

 of their descriptions. 



This is common in the upper horizon of the Pteranodon beds, 

 fragments being found in many places, but on account of the 

 fragile nature of the shell whole specimens are difficult to obtain. 



Inoceramus subtriangulat us, n. sp. Plate cxx, fig. 1. 



Shell (left valve) large, subtriangular, slightly convex, fi- 

 brous, greatest convexity in the antero-central region ; hinge 

 long, straight, composed of columnar fibers and crossed trans- 

 versely by costse ; length of hinge in type specimen, eighty mm. 

 Interior of shell smooth, ornamented with scarcely visible con- 

 centric lines or striae. Length of longitudinal axis, 200 mm.; 

 height of shell, 120 mm. Anterior lateral margin forming an 

 angle with the longer axis of the shell equal to the hinge angle. 

 Posterior margin curved, oval in outline. A single left valve 

 ( the type specimen) is imbedded in a matrix of chalk, from 

 which, owing to the fragile condition of the shell, it cannot be 



