159 



species here described, indicating a head or wider articulation of humerus. 

 No limb-bones are preserved. 



The vertebrae are too much injured lo be characteristic. One posterior 

 dorsal now has a compressed centrum, or, at least, not depressed. The infe- 

 rior face is convex transversely, and there is a slight concavity below each 

 diapophysis; but it is clear that it has been so modified by pressure as to 

 render its normal *hape a matter of uncertainty. 



Measurements. 



M. 



Parietal, length 0.074 



Parietal, width between the anterior ends of the crests 0. 048 



Parietal, least width 0.022 



Frontal, interorbital width 0.092 



Quadrate, width above 0. 020 



Quadrate, length from the pi t to the proximal end 0. 023 



Surangular, length of the lower edge 0.015 



Snrangular, depth in front of the cotylus 0. 300 



Surangular, depth at the end of the coronoid 0. 055 



Posterior dorsal, length 0. 04F5 



Scapula, proximal width 0. 051 



This species differs from all those of Mosasaurus and Liodon in which 

 the form of the quadrate is known in the character of that bone. From L. 

 IcetAs and L. congrops, in which that element is unknown, it differs in the 

 stouter or less slender vertebrae ; from L. proriger, in its much smaller size. 



Its size is a little less than the P. ictericus or L. validus. It is dedicated 

 to Professor Mudge in recognition of the valuable results of his investigations 

 as State geologist of Kansas. 



Platecarpus tectulus, Cope. 



Established on a number of cervical and dorsal vertebrae of smaller size 

 than those characteristic of the other species of the genus. The centra have 

 no', suffered from distortion under pressure. The articular surfaces are de- 

 pressed transverse-elliptic in outline, with a slight superior excavation for 

 the neural canal. A well-marked constriction surrounds the ball. 



There is a rudimental zygosphen, in the form of an acute ridge, rising 

 from the inner basis of the zygapophysis, and uniting with its fellow of the 

 other side, forming a production of the roof of the neural canal. The combined 

 keels become continuous with the anterior acute edge of the neural spine. 

 Thus, the form is quite different from that seen in the previously-described 

 species, and constitutes a lower grade of rudiment. The fact that this zygo- 



