Kansas University Science Bulletin. 



Vol. I, No. 9. SEPTEMBER, 1902. | To?, xi?™ 



RESTORATION OF DOLICHORHYNCHOPS OSBORNI, A NEW 



CRETACEOUS PLESIOSAUR. 



BY S. W. WILLISTON. 

 With Plate XI. 



No less than twenty-seven species and fourteen genera of 

 plesiosaurs have been described from the mesozoic deposits of 

 North America, with but few exceptions based upon very scanty 

 material. The earliest of these are from the Baptanodon beds 

 of the Jurasssic of Wyoming, and the latest is reputed to be 

 from the Laramie Cretaceous. Every intervening epoch, un- 

 less it be the Dakota, has furnished one or more species, but, 

 notwithstanding all this great diversity and wide geological 

 range, we have hitherto known but little concerning this order 

 of reptiles in America — less perhaps than of any other equally 

 extensive group. Enough, however, is already known to make 

 it certain that w r e have to do with a great diversity of types. 

 The following is a preliminary list of the American forms of 

 this order hitherto described : 



Plesiosaurus. 



lochwoodi Cope, Ext. Batrach., etc., 1869, 40. Cretaceous, New Jersey. 



brevifemur Cope, Cret. Vert. 256. Cretaceous, New Jersey. 



gu'o Cope, Proc. Acad. Nat. Sci. Phil., 1872, 128. Niobrara Cretaceous, 

 Kansas. 



occiduus Leidy, Proc. Acad. Nat. Sci. Phil., 1870, 74; Rep. Geol. Surv. 

 Terr., 1873, i, 345, pi. xv, ff. 11-13; Cope, Cret. Vert. Laramie Cretaceous, 

 Dakota. 



goutdii Williston, Kans. Univ. Quart, vi, 57. Comanche Cretaceous, 

 Kansas. 



mudgei Cragin, Fifth Publ. Colo. College Sci., 1894. Comanche Creta- 

 ceous, Kansas. 



shirley ensis Knight, Amer. Jour. Sci., x, 1900, 115. Baptanodon beds, 

 Jurassic, Wyoming. 



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