273 



Lines. 



Length of centrum beneath. 30. 



Breadth of articular ends. 40. 5 



Depth of articular ends 36. 



The better preserved of the caudals without diapophyses, represented in 

 Fig. 8, measures as follows : 



Lines. 



Length of centrum beneath 24 



Breadth of articular ends 38 



Depth of articular ends 30 



The researches of Professor Marsh have proved the mosasauroid reptiles 

 to have had four limbs constructed as paddles and adapted to swimming. 

 Previous to his discoveries it was supposed that posterior limbs were absent. 



Specimens of limb-bones, found in association with the vertebral specimens 

 above described, are supposed to belong to the posterior limbs, from the latter 

 pertaining to the back part of the column. 



The femur represented in Fig. 9, Plate XXXV, is a broad bone strikingly 

 different from the humerus of Cliclastes. The specimen is probably more 

 flat than in the normal condition, as its many fractures are evidences of its 

 having been crushed. 



The distal extremity is much the wider, and the upper extremity is but 

 little wider than the shaft. The head appears as a wide, lenticular, convex, 

 and very rugged surface. The lower extremity ends in a long, narrow, ellip- 

 tical, rugged surface for articulation with the bones of the fore-arm. From 

 the posterior part of the shaft there projects a thick, convex ridge, which 

 terminates above in an oval, flat, rugged surface, sloping from that of the 

 head of the bone. 



The rugged, articular surfaces of the femur would appear to indicate a 

 cartilaginous continuity with the contiguous bones more intimate than in 

 Clidastes. 



The measurements of the specimen are as follows : 



Lines. 



Length of femur 90 



Breadth of head - - 40J 



Breadth of distal extremity 69 



Breadth at narrowest part of shaft 34 



Thickness of head and trochanter 28 



Greatest thickness of lower extremity 17 



The remaining two bones I take to be those of the leg, though I am 



uncertain in regard to their relative position with each other and the femur. 

 35 g 



