244 



Galeocerdo iiartwjgllit, Cope. 



This species is of the G. egertonii group, i. e., with the cutting-edges 

 subequal and symmetrical. The basis is broad, and with convexities of the 

 fang, instead of the processes of the last species. The external parts 

 of the cutting-edge rise gradually from the base, and then more steeply at 

 an obtuse angle. They are convex on each side above, and meet symmet- 

 rically, forming a little less than a right angle. No denticles. Cementnm 

 smooth. Edge everywhere denticulate. One side of crown plane; the other 



convex. 



Measurements. 



M. 



Length of the basis 0.0215 



Length of tho fang 0.0195 



Elevation of tho apex (from the concavity) 0. 0145 



Width of tho crown at tho contraction 0.012 



This tooth is stouter and larger than that of G. egertonii, and was found 



beneath the bones of the Protostega gigas. It is named after Martin V. 



Hartwell, a member of my expedition, to whose acuteness and industry I owe 



many specimens. 



PTYCIIODUS, Agass. 



Ptychodus janewayii, Cope. 



Established on teetli resembling the posterior or pavement teeth 

 of Heterodontus. Their arrangement cannot be described, as they are only 

 known as separated specimens. Their surface is regularly convex, and 

 covered with a dense layer, which does not exhibit pores, and is thrown into 

 transverse or oblique ridges. No root is preserved in the specimens; but the 

 basis is coarsely porous. 



A small tooth, probably lateral, is an oval, with its surface thrown 

 into four folds, which traverse it obliquely from border to border. At the 

 base of the outer, at one end, is a series of adherent tubercles ; at the basis 

 of that at the opposite end is a broken fold, with tubercles at its outer base. 

 Length, ,n .0045 ; width, m .0025. A portion of a larger and more central 

 tooth has the surface with an unsymmetrical convexity, and crossed trans- 

 versely by fivefolds from border to border. 



Discovered by Prof. B. F. Mudgc, near Stockton, Kans., in a bed con- 

 taining man}' teeth of Oxyrhina, Lamna, etc., of small size. Dedicated to 

 Dr. John II. Janeway, post-surgeon at Fort Hays, Kansas, who has rendered 

 much important aid to paleontology and botany in Kansas. 



