WILLISTON : FISH TEETH FROM KANSAS CRETACEOUS. 41 



antiquus Desl., C. incisits Egert., C. Iwvis Gieb. and C. pygmceus 

 Munst. have been described from Europe, and C. crassidens Cope and 

 C. hartvelli Cope from the United States. 



Cor(i.t falcdtus. 



Cora.v faJcatvs Agassiz, Poiss. Foss. Ill, 220. pi. XXVI, f. U. XXVI^/, ff. 

 1-15: Woodward, Cat. Foss. Fishes Brit. Mus. I, 42J: 'where additional 

 synonymy will be found); Proc. Geol. Assoc. XIII, 198. pi. VI, ff. 13-15. 



Galeocerdo falcaius Leidy, Ext. Vert. Fauna West. Terr. ,301, pi. XVII, 

 ff. 29-42. 



Cenomanian and Turonian, England, France, Switzerland, Saxony, 

 Bohemia, Galicia. Russia ; Senonian of England and France ; Creta- 

 ceous of Texas, New Jersey, Mississippi ; Niobrara of Kansas. 



The very variable shape of the teeth referred to this species will be 

 seen in plate XIII, ff. 1-40. Possibly the specimens there figured 

 represent distinct species. C {Galeocerdo) crassidens Cope seems 

 to be represented by fig. 21, and C. ( Galeocerdo) hartvelli Cope (Cret. 

 Vert. 244) by fig. 23. Possibly this species also includes C. pristo- 

 dontus and C. lindstromi, both of which seem to be imperfectly dif- 

 ferentiated from C. falcaius at j)resent. 



In plate XIV, ff. 1-1^, are shown a number of teeth pertaining to 

 a single individual and found associated with many others, by Mr. 

 Martin, in the Niobrara Cretaceous of the Smoky Hill valley. Iso- 

 lated teeth of this species are the most abundant of the selachian 

 teeth in the Niobrara of Kansas. Only in very few instances have 

 many teeth been found associated, so that it is yet imi^ossible to fully 

 understand the dentition. The species occurs rarely, if at all, in the 

 lower Niobrara horizons, where those of OxyrMna and Ptychodus are 

 the most abundant. 



Cor<(.i- CHi'i-dta. n. sp. Plate XII, figs. 7, 8. 



Two specimens from the same block which yielded those of Ptycho- 

 dus janewayii and Lamna, species, aritea, seem evidently specifically 

 distinct from the foregoing. These teeth, while not differing much, 

 in outline from certain ones referred to C. falcatus, show a marked 

 variance in structure. In C. falcatus the outer surface of the tooth 

 stands out but very slightly. In C. curvata the crown is attached to 

 the root very obliquely, so that when resting upon a plane the tooth 

 forms a high arch, touching only by the extreme tips of the roots 

 and crown. The inner surface, also, is very much more uneven and 

 convex, the crown separated from the root by a marked, narrow, trans- 

 verse ridge, which is scarcely indicated in the teeth of C. falcatus. 

 Altitude, 8 mm.: greatest width, 14 mm.; horizon, lower or lowermost 

 Benton of Ellsworth county. 



