32 KANSAS UNIVERSITY QUARTERLY. 



ciently great to render the determination not improbable ; at least 

 with some of its varieties. 



Pfl/cho€lus martini, n. sp. Plate X. 



A large series of teeth, 110 in number, found together in the 

 Niobrara chalk of the Smoky Hill river, and collected by Mr. H. T. 

 Martin, cannot be indentified with any described species. I have 

 photographed them, arranged as symmetrically as possible, but with 

 no assurance that the arrangement is a natural one. In fact, it is 

 not improbable that the teeth belong to both upper and lower jaws. 

 The teeth apparently from the lower median row are much elongate 

 transversely, with a very flat crown, wherein they differ from the teeth 

 of other known species. The ridges are nine or ten in number, and 

 reach nearly to the lateral margin. In some of the teeth several of 

 the ridges form loops near the extremities. The marginal area of 

 granulations is small, and presents scarcely any distinct vermiculations. 

 The teeth of the lateral rows are less elongated than those of the 

 middle one, though still more so than is usual. The granulations 

 become rather more extensive in area proportionally in the small teeth, 

 as is the case with other species. A series ( left vertical row of the 

 plate) that may belong in the medio-lateral rows of the upper jaws are 

 more nearly square in shape, and the crown has a distinct, though low, 

 convexity extending over nearly its whole area. Antero-posteriorly 

 the surface is nearly flat, with a moderate convexity of the margin. 

 The surface posterior to the large grooves on the upper part shows 

 small, radiating and branched ridges. 



The largest teeth measure 45 by 20 mm.; the ones more nearly 

 square, 35 by 25 mm. 



Ptychodus (iiiomjmus. n. sp. Plate XI, figs. 5-8, 16-18, 20-22, 24. 



Seven teeth of nearly uniform size, four of them united in the ma- 

 trix, from Walnut creek, Kansas, seem to belong to a species distinct 

 from any previously described (figs. 16-18). They are of about the 

 same size as those described as P. uiJiippleyi and jP. occidentalis, but 

 will be distinguished from the former by the more broadly conical 

 crowns. In the teeth of this size of P. ivhippleyi the crown is much 

 compressed, standing up, tooth-like; in the present specimens they are 

 nearly straight or gently concave from the apex to the rims. From 

 P. occideiitalls the species will be distinguished by the very distinctly 

 reticulate marginal areas, the transverse ridges not reaching to the 

 rims of the crown. Other specimens agreeing in these characters are 

 from the Niobrara. The horizon is probably Benton. 



