350 



THE PORTLAND OOLITE PERIOD. 



CHAP. 



On the supposition that this and the previously described bone 

 constitute together the lower part of a pelvic arrangement, they are 

 so placed in the above diagram (CXLIIL). The bone more resembles 

 a monstrous tarsal, such as occurs in the middle line of the toe of 

 some liassic plesiosauri; but that would indicate a paddle 38 inches 

 broad, and a femur 24 inches broad, for which, at present, there 

 is no authority. 



A pubic bone, which came to the Museum complete as to figure 

 in the clay, but so broken into many fragments partly decayed 

 that it was not possible to replace the whole. Before the restora- 

 tion, the exact figure was taken, and the vacant spaces were filled 

 up to the true outline given in Diagram CXLIV. 



It is a large nearly plane trapezoidal bone, with two convex 

 and two concave sides, one angle being truncated by a slightly 

 sigmoidal surface. The symphysial line is curved, its depth 1*4 

 inch ; the articulating face is 6-3 long, and 2-4 deep. 



Diagram CXLIV. Pelvic bones of Pleiosaurus. Scale one-tenth of nature. 

 Arrangement of pelvic bones the pubic above, the ischial below. 



