58 



MAEINE EEPTILES OF THE OXEOKD CLAT. 



at their upper end is so complete that no trace of their original separation is visible, 

 and consequently the share of each in the articular surface for the ilium and in the 

 acetabulum cannot be made out. 



The femur (text-fig. 41) is a very much smaller bone than the humerus, the relative 

 lengths of the two being about as 2 to 3, while the difference in bulk is still more 

 striking. The proximal end of the bone is very massively constructed compared with 



Text-fig. 39. 



Left ischio-pubes of Ophihalmosaurus : A,, from outer side ; B, proximal end ; C, inner side ; 

 D, a second specimen from outer side (A, B, C, E. 2853, | nat. size). 



acet., acetabulum ; isch., ischium ; oh.f., obturator foramen; pu., pubis. 



the distal end, and it agrees generally in form with the proximal end of the humerus. 

 If, as in the description of the fore limb, we assume that the palmar face of the paddle 

 looks downwards and backwards, making an angle of about 45° with the vertical, then in 

 text-fig. 41, C, which represents the proximal end of the right femur, the line a-b shows 

 the direction of the paddle, a being at the top. The border marked a.i. is ventral, 

 ^vllile l.b. is anterior. The large trochauter-like ridge d.r. forms the postero-inferior 

 angle on the border,^.5, is at the top. As in the case of the humertis, the upper end 



