GEOLOGICAL SURVEY OF THE TERRITORIES. 405 



Inches. 



Length from end muzzle to first tooth 2. 5 



Width of muzzle at end 1. 5 



"Width of muzzle at anter. extremity nares 8. 



Width of premaxillary at anter. extremity nares 3. 3 



Width of maxillary between tenth and eleventh teeth 3. 2 



Depth mandible at extremity 2. 5 



Depth mandible at sixth tooth 3.5 



Depth pterygoid at transverse process 2. 5 



Width pterygoid at transverse process 1.4 



Width pterygoid in front 2.2 



Length pterygoid anterior to transverse process : 7.2 



Length crown fifth pterygoid tooth 1. 



Length crown second maxillary tooth 1.9 



Diameter crown second maxillary tooth at base 1.1 



The vomers are, as usual, separate and narrow. They are iu close 

 contact from the second maxillary to the second premaxillary tooth. 

 Thoughout this part of their length they are embraced by posteriorly 

 produced vertical laminae of the premaxillary bone. These laminae unite 

 just behind the second" premaxillary teeth and form a single prominent 

 keel, which disappears between the first premaxillary. 



LIODON MUDGEI, (COPE.) 

 (Proc. Amer. Philos. Soc, 1870, Dec.) 



I am not quite sure whether this species belongs to this genus or to 

 Mosasaurus. The characters of its quadrate bone, size, &c, induce me to 

 refer it provisionally to the former. Its determination rests on a series 

 of specimens from the yellow chalk at a point six miles south of Sheridan, 

 Kansas. They consist of three vertebrae and fragments of atlas, with 

 numerous portions of cranium and proximal extremity of scapula. The 

 parts of cranium preserved are the frontal bone without the anterior 

 extremity, and with the adjacent parietal almost complete, parts of the 

 basisphenoid, the suspensorium, the ossa quadrata, and the greater part 

 of the articular. The frontal is flat, with thin edge, longitudinally hol- 

 lowed on each side of the median line, which is marked by a low but 

 acute keel. There is an abundance of foramina and delicate grooves 

 on the surface, and posteriorly elevated striae, which converge to the 

 median keel. The median square projection of the border of the parie- 

 tal is in advance of the lateral portion of the same, and not behind it, 

 as in Clidastes propytlion. The fontanelle is large. A marked feature 

 is that the parietal crests unite into a low median ridge a short distance 

 behind the fontanelle, and are not, as in Clidastes projiython, separated 

 by a horizontal plane. The sutures of the bones forming the side of 

 the brain-case are very obscure. Nevertheless, it appears that the de- 

 scending margin of the parietal does not descend to the front of the 

 alisphenoid, but is margined inferiorly by the latter to the post-orbital 

 exxaansion. No part of the inferior margin of the alisphenoid can reach 

 the sphenoid, as it terminates 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 fur- 

 cate 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. 



The articular 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 



