34 KANSAS UNIVERSITY QUARTERLY. 



museum, without definite locality, seems to agree pretty well with 

 the Texas specimens, but the specimen is an uncharacteristic one and 

 may pertain to some other species. 



Some of the teeth referred to this species show a marked resem- 

 blance to those figured by Woodward (Cat. Foss. Fishes Brit. Mus. I, 

 pi. V, f. 2, P. rugosus), and by Dixon {P. altior Dix.) 



The European species is described as having the sides of the 

 median elevation of the crown smooth, which is not the case with the 

 present species, the grooves continuing midway into the lateral 

 granulations. 



Ttlichodns, sp. Plate XI, figs. 2, 3; plate XIII, fig. 53. 



Four teeth of moderately large size, from the Benton Cretaceous, 

 of Salt creek, Russell county, and two others of smaller size, also 

 from the Benton, seem to belong to a species distinct from any hith- 

 erto known. The larger ones will be distinguished from those re- 

 ferred to the upper series of P. martini, which are of nearly the same 

 size and shape, by the smaller area of transverse ridges, and the much 

 larger area of marginal reticulations, which are coarser. The teeth are 

 more nearly square and the convexity of the crown is greater. The 

 two teeth of smaller size i^robably belong with the others. It is pos- 

 sible that some of these teeth may belong with P. polygyrus. 



The other described species of this genus are the following : 



Ptychodus mammilaris Agassiz. — Senonian, Turonian, and Ceno- 

 manian, Europe. 



Ptychodus rugosus Dixon. — Senonian, England. 



Ptychodus decurrens Agassiz. — Senonian, Turonian, and Ceno- 

 manian, Europe. 



Ptychodus nadtistriatus Woodward. — Senonian and Turonian, 

 England. 



Ptychodus latissimus Agassiz. — Turonian and Senonian, Europe. 



Ptychodus papillosus Cope, Cret. Vert, 294. — Upper Cretaceous, 

 Colorado. 



Ptychodus triangularis Reuss. — Upper Cretaceous, Bohemia. 



Ptychodus levis Woodward. — Lower Chalk of England. 



SCYLLIID^. 



The family ScylliidciB comprises small sharks with sharp-pointed 

 cuspidate teeth, arranged in numerous series. The following genera 

 are given by Woodward (Cat. Foss. Fishes Brit. Mus. I, 838): Paleo- 

 scyllium Wagner, Lower Kimmeridgian of Bavaria; Scylliuni Cuvier, 

 Turonian and Senonian ; Pristiurus Bonaparte, Lower Kimmerid- 

 gian of Bavaria ; Mesiteia Kramb., Senonian and middle Eocene ; 



