S. W. Williston — North American Plesiosaiors. 233 



Museum, obtained a good many years ago from the Fort Hays 

 limestone, or basal strata of the Niobrara Cretaceous, of 

 Jewell county, Kansas, by B. F. Mudge. The specimen bears 

 the catalogue number 1640. Unfortunately, the specimen 

 had been injured in collecting before it fell into proper hands. 

 Originally it is probable that the larger part of the pectoral 

 girdle, and perhaps, also, of the pelvic girdle and hind limb had 

 been present, in addition to numerous vertebrae, and all in an 

 undistorted condition. The specimen, notwithstanding Avhat 

 it has suffered, is of much interest, since it is the only verte- 

 brate of which I have any knowledge from the Hays lime- 

 stone. Additional figures and descriptions will be given later. 

 For the present, the figures of the femur, ilia, and dorsal and 

 sacral vertebrae given in Plate IY will render the species 

 recognizable. A massive fragment of the scapula shows a 

 broad and firm union with its mate in the middle line. The 

 posterior projection of the coracoid is very long and much 

 constricted before its extremity, its distal width being a little 

 less than twice that of its least width ; the outer posterior 

 angle is acute and not much produced. The femur shows 

 facets for but two epipodial bones. 



Length of femur . . 33 V mm 



Greatest width distally . _ 206 



A rather common species referable to this genus from the 

 fence-post and lower horizons of the Benton is represented by 

 a number of specimens in the Kansas University collections, 

 and will be described later, with figures. 



Two additional species also referable to this genus are 

 known to me from the Hailey shales (probably equivalent to 

 the Benton Cretaceous) of Wyoming, and will be described 

 and figured later. 



Polycotylus Cope. 



The genus Polycotylus, described by Cope in 1870 from a 

 number of mutilated vertebrae and fragments of podial bones, 

 has remained hitherto much of a problem, and its characters 

 have been very generally misunderstood. Fortunately, there 

 is an excellent specimen in the Yale Museum (No. 1125), 

 collected now many years ago by the late Professor Marsh in 

 the vicinity of Fort Wallace, Kansas, from the Niobrara chalk, 

 which I believe can be referred with certainty to the type 

 species P. latvpinnis Cope. That it belongs in the genus 

 Polycotylus is beyond dispute, the vertebrae agreeing quite 

 with the type as they do. This species seems to be the most 

 common one of the order in the Kansas chalk, and is repre- 

 sented by several other specimens in the Yale Museum and by 

 specimens in the University of Kansas collection. It is not at 



