232 S. W. Williston — North American Plesiosaurs. 



tunity of again examining the type specimen. I therefore 

 place the Yale specimen for the present in this species. 



The characters of the pelvis, that is, the short ischia espe- 

 cially, and the shape of the pubis, will be readily appreciated 

 by an examination of Plate I. The paddle is especially note- 

 worthy because of the primitive number of the epipodial 

 bones (there are no supernumeraries), and this character I have 

 also observed in the paddles of three other species of the 

 genus. The paddle, it is also observed, is much elongated, 

 and the femur is relatively short (Plate II, figure 1). The few 

 vertebrae of the neck preserved are quite elasmosaurian in 

 character. Other propodials of this species are preserved in 

 the University of Chicago collections. 



Elasmosaurtis stembergi n. sp. Niobrara Cretaceous of Kansas. 



The only parts referable with certainty to this species are 

 two complete dorsal vertebrae and some additional fragments 

 in the University of Kansas collection, obtained some years 

 ago by Mr. Charles Sternberg in the yellow chalk of Gove 

 county, Kansas. I describe them, nevertheless, since they 

 indicate the largest plesiosaur of which I have any knowledge. 

 If they belonged to a long-necked form like E. platyurus, the 

 animal could not have been less than sixty feet in length. 

 That they pertain to a long-necked form is quite certain, and 

 the general characters of the vertebrae are like those of JElas- 

 mosaurus. 



The dorsal centra are nearly circular in outline, somewhat 

 broader than high, with their sides gently concave. The dia- 

 pophyses are stout, directed upward and outward to a plane 

 above the zygapophyses. The zygapophyses are separated by 

 a notch and are rather small. The spine is flattened and elon- 

 gate. Figures of these vertebrae will be given in a later com- 

 munication. 



Width of dorsal centrum .. ] 65 mm 



Height of same 140 



Length of same .., 80 



Width of more posterior dorsal . .. 155 



Height of same _ _ 143 



Length of same . 18 



This is the only specimen referable to this species that I 

 have ever seen in the many years of my acquaintance with 

 the Kansas saurians. Its extreme rarity will therefore justify 

 the description of the rather meager material. 



JElasmosaurus nobilis n. sp. Niobrara Cretaceous of Kansas. 



A very large specimen referable to a new species is repre- 

 sented by a considerable portion of a skeleton in the Yale 



