174 



KANSAS ACADEMY OF SCIENCE. 



A NEW PLESIOSAUR FROM THE NIOBRARA CRETACEOUS OF KANSAS. 



BY S. W. WILLISTON. UNIVEESITY OF KANSAS. 



During the past summer. Judge E. P. West, of the University of Kansas, ob- 

 tained from the chalk of western Kansas a specimen of a plesiosaur. which is of 

 especial interest, both by reason of the comparative rarity of these animals and of 

 the nature and preservation of the remains obtained. The specimen comprises the 

 skull and twenty-eight cervical vertebra?, all attached and with their relative positions 

 but little disturbed. They lie upon the right side, with the usual opisthotonic curve 

 to the neck, and are all laterally compressed. The right side of the skull is not at 

 aU disturbed, save from the effects of compression and of chemical action upon the 

 teeth. The upper side, however, though the teeth are in perfect preservation, and 

 the relative positions of the mandible and maxilla are unchanged, has been crowded 

 up about three inches, nearly obliterating the orbit. 



In the absence of other material for comparison, and some of the necessary liter- 

 ature. I shall not attempt to enter into a full description of the specimen, but shall 

 reserve such for another time, when my opportunities will be greater. Most of the 

 sutures will, I believe, be traced out. but at present I have not sufficiently distin- 

 guished some from the cracks due to compression. In the figure herewith given I 

 have indicated such onlv as are bevond doubt. 



S.W.W. 



.Skull of Ciiiioliosdurus I Eh(sinosai(riis.' ) Snowii Will., iiboiit 



SKULL. 



Parietals. The parietals form a high, steep, roof-like covering, ascending into a 

 sharp, thin sagittal crest, extending through nearly their whole length from near 

 the attachment of the squamosals posteriorly as far forward as the posterior part of 

 the orbit. This crest, throughout most of its extent, forms a plate of bone with 

 nearly parallel sides for about two inches vertically, its thickness on the margin 

 varying from two to four millimeters, and its entire length about loO millimeters. 

 Posteriorly they expand into a thickened triangular process, directed upward and 

 backward over the supraoccipital — for union with the squamosals. Extending the 

 whole length of the crest is a well-marked suture, and it is possible that at or near 

 the anterior extremity there may have been a parietal foramen: but, if so, the open- 

 ing has been closed by the compression. 



Frontalf'. -The frontals are small bones: neither the anterior or posterior sutures 

 have been traced, but. allowing for compression, the distance between the upper 

 borders of the orbits could not have exceeded three inches. The two bones meet in 

 a roughened suture, which, for more than an inch, seems to have been imperfectly 

 closed in life. 



