406 GEOLOGICAL SURVEY OF THE TERRITORIES. 



margin of the glenoid cavity (cotylus) to commencement (or end) of 

 coronoid suture, indicating a shortening of the posterior part at least 

 of the cranium. The hone is continued forward only immediately under 

 the coronoid, (c. f. r. L. ictericus.) 



The proximal extremity of the quadrate is characteristic, and exhibits 

 features intermediate between those of Liodon ictericus, Cope, and the 

 typical species of Mosasaurus, as M. fulcidtus, M. dekayi, &c. The proxi- 

 mal articular face is much like that of M. depressus, (Trans. Ainer. 

 Philos. Soc, 1869, p. 187, Fig. 48, No. 3.) The external angle is much 

 smaller than in the Liodons and more anterior; nevertheless it is con- 

 tinued distally as a ridge-like angle separating the antero-lateral from 

 the postero-lateral faces, as in them, and not presenting the gradual 

 blending of the two surfaces, characteristic of the genus Mosasaurus. 

 The postero-lateral face is thus flat proximally, and the meatal pit, which 

 is well developed, cannot be seen from the antero-lateral face. The 

 distal part of the quadrate is lost so that I cannot determine the char- 

 acter of the ridges there. . 



The basal element of the axis -bears a strong hypapopbysis without 

 articular faces, but very rugose surfaces. The same portion of the atlas 

 is a convex parallelopipedon with median rugose tuberosity, and very 

 rugose extremities. Its surface is not separated from its body anteriorly 

 by a deep groove as in Liodon. 



The articular facets of the scapula are much broader than in the other 

 species here described, indicating a head or wider articulation of the 

 humerus. No limb bones were preserved. 



The vertebras are too much injured to be characteristic, with one ex- 

 ception. This one is a posterior dorsal, and had had compressed 

 centrum, or, at least, not depressed. The inferior face is convex trans- 

 versely, and there is a slight concavity below each diapophysis. 



Measurements. 



M. 



Parietal length 0.074 



Parietal width between anterior and crests 048 



Parietal least width 022 



Frontal interorbital width .092 



Quadrate width above 002 



Quadrate length from pit to proximal end 0.023 



Articular length, lower edge 015 



Articular depth, in front of cotylus * ' 035 



Articular depth at coronoid 055 



Posterior dorsal length 0.495 



Scapula, proximal width 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. Icevis and L. congrops, in which that element is unknown, it differs in 

 the stouter or less slender vertebras ; from L. prorigerin its much smaller 

 size. 



Its size is a little less than the L. ictericus or L. validus. It is dedi- 

 cated to Professor Mudge, in recognition of the valuable results of his 

 investigations as State geologist of Kansas. 



LIODON ICTERICUS, (COPE.) 

 (Proceed. Amer. Philos. Soc, December, 1870.) 



Characteristics : External angle of the osquadratum close by the mea- 



