42 KANSAS UNIVERSITY QUARTERLY. 



Leptostyrd.v, gen. nov. Plate VI, figs. 3, 15, 15a; plate VIII, fig. 7. 



Leptosiyrccv hicusj^idatus, gen. et sp. nov. 



Principal cusp long and slender, flattened upon the outer side, with 

 sharp, smooth edges and a median convexity in the middle of the 

 flattened surface ; for the most part convex longitudinally, gently 

 concave before the apex. Inner surface strongly convex from side to 

 side, concave on the lower half longitudinally, gently convex on the 

 upper part. A single denticle present, slender, flattened cylindrical, 

 with an anterior and posterior carina ; it arises below the base of the 

 main cusp, and is directed more outwards, its inner surface concave 

 longitudinally. Immediate base of crown of both main cusp and 

 denticle" with short ridges. Base of tooth short, truncate ( ? ) below 

 the main cusp, prolonged downward below the denticle. Length of 

 main cusp, 19 mm.; width of same at base, 5 mm.; length of denticle, 

 5 mm.; width of same at base, 2| mm.; height of tooth, 26 mm.; width 

 of base, 10 mm. 



A small tooth of the same form found with this has a total length 

 of 14 mm. The base is deeply emarginate below, with two slender 

 roots; that below the denticle the longer. Mentor beds, 4i miles 

 southwest of Marquette, Kan. 



U. S. Nat. Mus. No. 1979. 



