2 PKOCEEDINGS OF THE GEOLOGICAL SOCIETY. [NoV. 7, 



Viewed sideways, the shaft of the bone is, for the greater part of 

 its length, nearly straight, though its dorsal contour is a little convex. 

 But towards the proximal end it becomes widened and flattened from 

 above downwards, while, at the same time, its longitudinal contour 

 becomes concave above and convex below. 



In its dorsal, or upper, aspect also, the greater part of the length of 

 the shaft of the bone is nearly straight ; but at nine inches from the 

 proximal end it curves so as to have a convex outer and a concave 

 inner contour. The latter curve takes a broad and gradual sweep. 

 In consequence of the various curvatures and other changes of form 

 which have been described, the broad and J&attened proximal end 

 of the femur is, as it were, twisted upon the more cylindroid shaft, 

 the long axis of its section forming an acute angle with that of the 

 shaft. 



The outer surface of the greater part of the shaft of the bone is 

 somewhat flattened. Just where the proximal end begins to bend 

 inwards, the junction of the outer and the upper faces rises into an 

 obtuse ridge, nowhere more than an inch broad and as much high, 

 which is continued for about four inches upon the outer or convex 

 edge of the incurved proximal part of the bone, and ends, in an obtuse 

 summit, at 5-75 inches from the proximal end. 



The surface of this outer trochanteric ridge is unbroken very 

 nearly to its proximal end ; so that if it were ever continued into a 

 free process, this must have been comparatively short and slender. 



Erom its inner and under side the shaft of the femur gives oif a 

 very stout process, the greater part of which is broken away. Enough 

 remains, however, to show that one of its faces had the same direc- 

 tion as the tibial (or inner) face of the femur itself. 



The anterior end of the fractured surface, indicating the attach- 

 ment of the base of this inner trochanter, is 18-5 inches distant from 

 the proximal end, and the surface is about 8 inches long ; so that its 

 centre must have been situated on the proximal side of the middle 

 of the length of the uninjured bone. A broad, but very shallow, 

 depression marks the inner face of the femur above the base of this 

 process. 



The various se(?tions presented by the ends of the fragments of the 

 bone show that it contained a large and distinct meduUary cavity, 

 having a diameter of from two and a half to three inches. 



The peculiar form of this femur, with the characters and position 

 of its trochanters, leave no doubt as to the Dinosaurian affinities of 

 the animal to which it belonged. 



In size it must have corresponded with Megcdosaurus and with 

 moderately large Iguanodons. The largest femur of an Iguanodon 

 with which I am acquainted is that marked JSTo. 1 in the British 

 Museum. It is 44-5 inches long, the middle of its shaft having a 

 transverse diameter of 8 inches. 



The Iguanodont femur in the British Museum figured by Pro- 

 fessor Owen in his monograph upon that Beptile, pubhshed by the 

 Palseontographical Society (pi. 15. fig. 1), is 33 inches long, the 

 transverse diameter of the middle of the shaft 'being 5 inches. 



