88 University of Kansas Geological Survey. 



Cipley. In the interior of North America the type, so far as 

 known, begins near the lower part of the Niobrara and termi- 

 nates at its close or in the beginning of the Fort Pierre ; that is, 

 to use the European time periods, with the close of the Turo- 

 nian or the beginning of the Senonian. Forms ascribed to this 

 genus, the Liodon of Cope, are from the Lower Greensand or 

 Lower Marl of New Jersey, but their positive identification is 

 yet uncertain, if not doubtful, since the only characteristic 

 parts, the rostrum, quadrate, and limb bones, have never yet 

 been found. There is nothing improbable in its occurrence in 

 these beds, but hitherto nothing decisively characteristic of 

 Tylosaurus has been found there. The genus Hainosaurus is 

 clearly of the Tylosaurus type. In fact, the two genera are so 

 nearly related that decisive distinctional characters are not yet 

 forthcoming, unless they be found in the paddles. 



The Platecarpinae have a very similar distribution. Begin- 

 ning in the Cenomanian of New Zealand, in Taniivhasaurus , if 

 the deposits of New Zealand are really contemporaneous with 

 this epoch in Europe, they terminate in the closely allied Plio- 

 platecarpus Dollo from the Lower Maestrichtian of Belgium. In 

 North America the species upon which the genus Platecarpus 

 has been chiefly based are known nowhere outside of Kansas 

 and Colorado, and are here restricted exclusively to the Nio- 

 brara. The type species of this genus, P. tympaniticus Cope, is 

 from Mississippi, and is in all probability congeneric with the 

 Kansas species, but this has not yet been satisfactorily proven, 

 though it certainly belongs in the Platecarpinse. 



From the Fort Pierre only one species can be referred to this 

 group, and this with doubt. Brachysaurus described by myself 

 may belong here, but I believe that its affinities are more close 

 with the Mosasaurinre. It is certainly closely related to Prog- 

 nathosaurus Dollo, 3S from the L T pper Senonian of Belgium, and I 

 should have had little hesitancy in identifying it with that 

 genus had not Dollo stated that the chevrons are free in Progna- 

 thosaurus , 39 



38. Mem. Soc. Belg. de Geol., in, 193, 1889. 



39. Mem. Soc. Belg. de Geol., iv, 163, 1890. 



