TWENTY-THIED ANNUAL MEETING. 177 



The sixth vertebra has the spine nearly perpendicular, and the pleurapophyses 

 broad, with more marked terminal anterior and posterior prolongations. 



SIXTH CERVICAL VEKTEBB A. 



Length of centrum 48 milliiu. 



Height of centrum 4l! 



Height of spine above floor of cMnal 47 ' " 



Width of spine 'Af> 



NINTH CERVICAL VERTEBRA. 



Length of centrum 53 millini. 



Height of centrum 42 



Height of spine above floor of canal 47 



Width of spine 40 



Length of pleurapophyses 40 



Least width of pleurapoijhyses 25 



Greatest width of pleurapophyses, distally 49 



FOURTEENTH CERVICAL VERTEBRA. 



Length of centrum 65 mlUini. 



Height of centrum 50 



Height of spine 50 



Width of spine 4'2 



Length of pleurapophyses 48 



Least width of pleurapophyses 32 " ' 



Greatest width of pleurapophyses, dislally 56 " 



TWENTIETH CERVICAL VERTEBRA. 



Length of centrum 78 millini. 



Height of centrum 60 



Height of spine 62 ' ' 



Width of spine 65 



Greatest width of pleurapophyses, distally 65 " 



TWENTY-SEVENTH CERVICAL VERTEBRA. 



Length of centrum 90 millini. 



Height of centrum 68 



TWENTT-NINTH ? THIRTIETH? CERVICAL VERTEBRA. 



Height of centrum 77 millim. 



Width of centrum 74 



Depth of cup 12 



SYSTEMATIC POSITION. 



In the absence of any definite knowledge of the skull-structure of other American 

 ]olesiosaurs. and not very much knowledge, and that in a measure contradictory, of 

 the European forms, it is a matter of some ditficulty to correctly refer the present 

 species to any definite genus. In Science, vol. XVI, p. 262, 1 provisionally referred it 

 to Cimoliosaurus Leidy. under the name C Snoivii, in honor of Chancellor F. H. Snow. 

 But the genus Cimoliosanriis, as defined by Lydekker, will include absurdly compos- 

 ite forms. Among the material in the museum of the University of Kansas there 

 are a dozen or more specimens from the Kansas Cretaceous certainly referable to at 

 least three distinct genera, all of which might be included in Cimoliosaurus of Lydek- 

 ker and Zittel. 



It cannot be denied that there is a striking reserrtblance between our present skull 

 and that described by Sollas ( loc. cit.) as Plesiosaurus Conybeari Sollas, and I am 

 strongly tempted to believe that the two forms are congenerous. On the other hand, 

 such a definition of Plesiosaurus as the following, from Zittel's Hand-Buch, vol. Ill, 

 pp. 489 and 490, will prohibit the admission of our species: "... Augenhohlen 

 rundlich. ungefahr in die Mitte der Schadellange, ohne verknocherten Skleroticaring; 

 Schlafenlocher gross, vierseitig. ■ . . . Scheitelbeine verschmolzen, schmal und 

 kurz; Jochbein kraftig, gebogen; Quadrat jochbein nach hinten vorspringend, die 

 seitliche Hinterecke des Schadels bildend. . . . Zahnbeine vorn zu einer breiten 



