﻿66 



FOSSIL REPTILIA OP THE 



articular surface for the inner femoral condyle may be recognised at a , and that for the 

 outer condyle at b, fig. 3, PI. XXI. A procnemial plate (c), with a base of 7 inches in 

 extent, projects forward 4 inches beyond the articular part of the head of the bone. As- 

 wrought out of the matrix this plate shows a sharper free border than probably was 

 natural ; its obtusely rounded summit, d, has retained its condition as an epiphysis. The 

 diameter of the head of the tibia in the direction of the procnemial prominence («, c, fig. 5) 

 is 11 inches. The preserved longitudinal extent of the tibia is 2 feet. The two 

 diameters of the fracture (/, fig. 3) are 4 inches 6 lines and 3 inches 6 lines. The 

 indication of a medullary cavity at the fracture if) are hardly so definite as in fig. 6, and 

 such as it is, the cavity was short ; for at the fracture (<?) the corresponding central 

 portion of the shaft shows an open osseous tissue with wide chondrosal interspaces. 



In the obliquely fractured and partly crushed end of the shaft the trace of medullary 

 cavity has disappeared. The osseous tissue of the rest of the shaft is compact. Not- 

 withstanding the degree of crushing, the beginning expansion in the tibio-fibular 

 direction and of contraction or flattening in the rotulo-popliteal direction is unmistak- 

 able, and has led me to conclude that the distal, more flattened end of the bone is that 

 which is wanting in the present specimen. 



§ 16. Doubtful pakts of Hind Limb. — Exterior to the right femur and overlain by 

 it is the shaft or slender part of a bone, 16 inches in length and 3 inches in breadth; 



it bears the proportion of a fibula to the tibia above described. 



No recognisable tarsal, or other bone of the hind-foot, has been 

 detected in the indurated matrix forming the bed of the Omosaur. 

 But Professor Phillips, in his instructive 4 Geology of Oxford/ 

 states, 1 44 Three metatarsals in the Oxford Museum, apparently of 

 Megalosaurus, lying in their original apposition, have been obtained 

 from the Kimmeridge Clay of Swindon and seem to indicate a 

 tridactyle foot (diagram lxviii)." I subjoin a copy of the cut of 

 these bones (Fig. 11), deeming it more probable that they belonged 

 to the genus of Dinosaur now known to have left remains in 

 that formation and locality, than to the Megalosaurus, of which 

 no indubitable evidence has yet been obtained from Kimmeridge 

 Clay, either at Swindon or elsewhere, a is an outline of the 

 proximal, b of the distal, ends. 



These bones exemplify the 4 leptopodal ' character of the 

 Dinosaurian foot, due to the reduction of thickness or breadth by 

 suppression of two of the toes, and a consequent departure from the short, thick, or broad 

 4 pachypodal ' character of the pentadactyle hind foot of the existing and extinct terrestrial 

 Chelonia. 



Fig. 11. 



Metatarsals of Omosaurus ? 



1 P. 215. 



