94 KANSAS UNIVERSITY QUARTERLY. 



beak of tlie lower valve. The test of the lower valve is uuich 

 thinner than that of tlie upper one. 



Measurements: 



Length 30 mm 



Width 20 " 



Height 15 " 



Locality: Saline river, Ellis county, Kansas. 



Geological horizon: Rudistes beds, Niobrara Cretaceous. 



Remarks. — This form is more nearly related to O. jevuellejisis than to any other 

 species. It differs from that species in that its borders are not contracted in front 

 of the beak; that it possesses crenulations and in that it is more convex. The 

 latter might be due to an accident of growth but the other characters remain con- 

 stant in all the specimens examined. 



Ostrea leeii, n. sp. Plate XXI, Figs. 10, n. 



Shell (right valve), thin, irregular in shape, medium size, very 

 slightly convex; surface crossed transversely from beak to posterior 

 border by a series of rounded ridges and more or less deep grooves 

 which show on the inner surface of the shell as ridges; beak 

 sharply pointed, turned a little toward ventral margin; anterior 

 portion of the shell forming a short neck to the expanded posterior 

 portion. 



The ventral side of the shell slopes more than the somewhat 

 abrupt dorsal side; ventral border slightly concave; dorsal border 

 possessing- a deep inward curve; posterior border broadly rounded. 

 Lower valve unknown. 



Measurements: 



Length 40 mm 



Width 25 " 



Height 10 " 



Locality: Solomon river, Phillips county, Kansas. 



Geological horizon: Rudistes beds, Niobrara Cretaceous. 



Remarks. — Only a few specimens of this species have been collected, and these 

 from one locality. The specimen figured is the best preserved one of the collec- 

 tion. 



Ostrea lata, n. sp. Plate XXII, Figs. 7, 8, 9, 10 



Shell (right valve) thin, ablong, slightly convex; beak pointed 

 and turned downward; surface of shell rising moderately abruptly 

 to anterior one-third of shall, thence sloping very gradually to the 

 posterior border; sides of shell symmetrical; exterior surface 

 marked near the borders by light lines of growth; ventral border 

 nearly straight; dorsal [;order slightly convex; posterior border 

 forming an obtuse point. 



