F. B. Loomis — New Mosasaur from the Ft. Pierre. 563 



regions the caudals are robust, but toward the rear become 

 more and more flattened from side to side. 



Length of the cervical series (7) 260 mm 



Length of the dorsal series (22) 1265 



Length of the pygal series (5) 250 



Length of the caudal series (25 = 1050 mra ) 



estimated 2200 



Length of the skull 510 



4485 mm _ a b ou t is feet. 



The ribs are single headed and simple. Their varying length 

 give an idea of the size of the body as follows : 



Dorsal rib 



Cervical rib 3 



r^mrr 



a a 



4 





tt tt 



5 



116 



a it 



6 



132 



tt a 



1 



475 



Dorsal rib 



1 



320 



U it 



2 



330 



U it 



3 



350 



it tt 



4 



410 



a a 



5 



390 + 



6 



420 mm 



7 



370 + 



8 



408 



9 



370 



10 



350 



11 



202 



12 



175 



13 



160 



14 



155 



15 



140 



The ossified portion of the scapula has the distal articular 

 end greatly thickened, its rounded roughened surface showing 

 two faces, both convex, the one for the coracoid, the other for 

 the humerus. The neck is strongly constricted ; the anterior 

 margin is the shorter, and deeply concave ; the posterior border 

 is longer and less concave ; the proximal border is rogose and 

 highly convex. The bone as a whole is flat and moderately 

 thin. 



The coracoid is larger than the scapula but like it a fan- 

 shaped bone. The articular end is not as swollen as that of 

 the scapula, and it presents two surfaces, the one for the sca- 

 pula, the other for the humerus. The anterior margin is short 

 and slightly concave ; the posterior margin longer and much 

 more concave ; the inferior border is convex, and about a 

 fourth of the way from the front has a deep notch as seen in 

 the figure (fig. 7). I do not find beside this a coracoid fora- 

 men as is typical for Platecarpus. 



The humerus is remarkable for its distal width, being 

 actually greater than the height of the bone (exaggeration 

 of Platecarpus). The proximal end is only slightly convex, 

 the articular surface being greatly thickened opposite the 

 pectoral process. The distal end makes nearly a half circle, 

 the articular surfaces for the radius and the ulna being thick- 



