LIASSIC DINOSAURS. 113 



Pelvic Arch and Limb. Pis. 53, 57, 58. 



The left iliac bone (PL 53, figs. 1 and 2, 62) retains almost its natural relations 

 with the sacrum. The right iliac bone (ib., 62) has been obliquely dislocated. It 

 is a long bone, with a sigmoid flexure (ib., fig. 2, 62), convex upward and outward 

 in its anterior two thirds, more slightly concave in the rest of its extent. Of 

 the left ilium an extent of 18 inches is preserved, a part, apparently a 

 small one, being wanting from both extremities. The narrowest portion of 

 the bone is that which is produced anterior to the first sacral rib (ib.,sl); 

 this portion is 6 inches in extent, triedral in form, 2 inches 6 lines in breadth 

 where it joins the obtuse, expanded end of that rib. Beyond or behind the 

 first sacral abutment the ilium progressively expands to a breadth of about 5 

 inches opposite the fourth abutment (« 4). The thickness of the bone, as exposed 

 in the fracture of the left ilium, is from 2 inches to 2^ inches. The middle 

 third of the substance of the bone shows a rather open, cancellous structure ; 

 external to this the texture is much closer, with a compact, peripheral layer of from 

 1 to 2 lines in thickness. The articular cavity for the femur is on the under and 

 outer side of that part of the ilium which is opposite its symphysis with the first 

 two sacral vertebrse (s 1 and s 2). 



The fore part of the right ilium (g2') has been thrust away from that junction, 

 and the femur (65) is dislocated, passing beneath the ilium, with the head abutting 

 against the sacrum. The summit of the great trochanter terminates rather more 

 than an inch below the articular head of the bone. The breadth of the femur 

 across this part of the trochanter is 3 inches 6 lines. The length of the femur 

 (PI. 57, fig. 1, 60) is 1 foot 4 inches. The inner process or ridge {t) begins to be 

 developed about 5^ inches from the head of the bone, and is 2 inches in extent. 

 The shaft of the bone at this part is rather flattened, both anteriorly and posteriorly, 

 and is most convex externally. It assumes a rounder circumference about 1 inch 

 below the inner process, where the bone is 2 inches 4 lines in diameter. Thence 

 it expands to the condyles (a and j), becoming flattened anteriorly and concave 

 posteriorly. The condyles are but feebly indicated by a shallow notch on the fore 

 part, but more distinctly behind, where they are produced backward. The hind 

 extremity of the outer condyle (j) is marked off by a notch from the rest of its 

 articular surface lying anterior and external to it. This posteriorly defined part 

 articulates with the outer condyloid production of the head of the tibia, the fibula 

 articulating with the rest of the outer condyle. The transversely convex fore part 

 of the shaft of the femur is divided on each side by a low ridge from the flattened 

 surfaces converging towards it, the one from the outer side, the other from the 

 inner process (t). The exterior of these ridges is continued further down the bone 

 15 



