158 



case are very obscure. Nevertheless, it appears that the descending margin 

 of the parietal does not descend to the front of the alisphenoid, but is mar- 

 gined inferiorly by the latter to the postorbital expansion. No part of the 

 inferior margin of the alisphenoid can have readied the sphenoid, as it ter- 

 minates in a thin edge, except for a short distance medially, where it is 

 broken off. 



The inferior aspect of the parietal and frontal bones presents a furcate 

 keel corresponding to the divergent parietal crests, and a very large funnel 

 for the epiphysis of the brain. The olfactory groove is deep and regular, and 

 open like that of P. ictericus. 



The surangular bone is characterized by the prominent longitudinal crest, 

 which descends on the inner side, from the front of the glenoid cavity to 

 below the posterior attachment of the coronoid bone, where it terminates in 

 a thin edge ; also, by the short distance between the 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 bone is con- 

 tinued forward only immediately under the coronoid (cfr. P. ictericus). 



The proximal extremity of the quadrate is characteristic, and exhibits 

 features intermediate between those of Platecarpus ictericus, Cope, and the typ- 

 ical species of Mbsasaurus, as M. fulciatus, M. dekayi, etc. The proximal artic- 

 ular face is much like that of M. depressus (Transactions of the American Phi- 

 losophical Society, 1863. p. 181, Fig. 48, No. 3). The internal angle is much 

 smaller than in the Liodons, and more anterior; nevertheless, it is continued 

 distally as a ridgelike angle, separating the antero-lateral from the postero- 

 lateral faces as in them, and not presenting the gradual blending of the two sur- 

 faces characteristic of the genus Mosasaurus. The postero-lateral face is thus 

 Hat proximally : and the meatal pit, which is well developed, cannot be seen 

 irom the antero-lateral face. The distal part of the quadrate is lost, so that I 

 cannot determine the character of the ridges there. 



The basal element of the axis bears a strong hypapophysis without artic- 

 ular laces, but very rugose surfaces The same portion of the atlas is a con- 

 vex parallelopipedon. with median rugose tuberosity and very rugose extrem- 

 ities. Its surface is not separated from its body anteriorly by a deep groove, 

 as in P. ictericus. 



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



