CRETACEOUS FORMATIONS. 



39 



irregularly grooved, and with a large deep hemispheric pit on one side above the 

 surface, but not on the other. 



The above-described long bones were taken back by Professor Rogers to America ; 

 the following specimen he liberally permitted me to retain. 



A metacarpal or metatarsal bone rather larger than the preceding, with the notch 

 at the proximal end much less deep. The angular border or ridge, continued from 

 one of the posterior rounded angles of the articular surface, quickly subsides ; that 

 from the other angle is continued down from the middle of the shaft, giving it an oval 

 transverse section. The fracture of the shaft, nine inches from the head of the bone, 

 exposes an oval medullary cavity, nine lines in the long diameter. The longitudinal 

 ridge is developed from the distal half of the bone, as in the former, and it terminates 

 in a simple convex condyle with the grooved sculpturing upon the articular surface, and 

 with the large deep hemispheric pit for a ligament, on one side of the trochlea, and 

 a large shallow notch on the opposite side. 



The following two bones of the toes conform to the Lacertian type, and not to that 

 of the Enaliosauria. The first is a proximal phalanx of a toe of apparently the same 

 Saurian as the bone last described. The proximal articular surface appears to have 

 been subcircular, very slightly concave, with a few shallow pits and grooves in the 

 middle, like those on the end of the metatarsal. The shaft gradually contracts, and 

 becomes more convex in front than behind ; it subsides into a shallow depression 

 above the forepart of the distal trochlea, on each side of which there is a large and 

 deep ligamentous pit. Its dimensions are as follows : 



Inches. 



Extreme length ........ 



5 



Breadth of upper articulating surface .... 



91 



-2 



Depth of ditto ........ 



. . 2i 



Breadth of lower articulating surface .... 



. . If 



Depth of ditto ........ 



2 



The second specimen is a second phalanx of apparently the same toe ; having an 

 expanded, concave, proximal, articulating surface, adapted to the distal surface of the 

 preceding bone ; and terminated by an oblique broad convex trochlear articulation. 

 Its dimensions are as follows : 



Extreme length 



Breadth of upper articulating surface 



Depth of ditto 



Breadth of lower articulating surface 



Depth of ditto 



Inches. 



2 

 2 

 U 



On the highly probable supposition that the above-described long bones belong to 

 the Mosasaurus, they indicate the extremities of that gigantic lizard to have been 



