32 
FOSSIL REPTILIA OF THE 
2 feet. It is much shorter in proportion to the trunk (as reckoned from the first 
dorsal (ib., fig. 1, d) to last sacral (ib., s) than in the Plesiosaurus Itomalospondylus 
(Tab. V), and differs in the more proximal position of the metacarpal of the fifth digit, 
and in the smaller size of the radial carpal of the distal row. 
Like the scapula in the pectoral arch, the ilium (Tab, IX, 62 ) is the smallest bone 
of the pelvic one; it is 5 inches, in length, inch across the obliquely truncate upper 
(proximal or sacral) end, it contracts to a diameter of 9 lines at its middle, and then 
expands to a breadth of 2 inches ,4 lines, with proportional thickness, at its lower 
acetabular end. The stem is subcompressed, convex transversely, and also longitudi- 
nally at the upper half, which shows a low ridge externally, and is longitudinally 
striate near the margin of the surface connected with the sacral pleurapophyses, from 
which, as before stated, it has been dislocated. The acetabular end preserves its 
natural connections with the corresponding thickened part of the ischium (ib., 63 ), 
which on both right and left sides is interposed between the ilium and pubis. The 
rough acetabular surface is nevertheless continued from the ischium upon the pubis, 
for about two inches of the contiguous border. The head of the femur is applied to 
the ischio-pubic surface in both limbs, yet the better proportioned articular depression 
is that formed by the ilium and ischium, from which it seems as if the femur had been 
dislocated forward. As, however, the mode of attachment has been by a ligamentous 
mass, this may have converged from the whole of the antero-posteriorly extended 
acetabular surface to the head of the thigh-bone, allowing a certain freedom of play of 
the bone forward and backward ; the diameter of such acetabular surface, lengthwise, 
is 5 inches, the greatest vertical diameter is 3 inches. 
The ischium (Tab. IX, 63 ), as it passes from the acetabulum mesiad, loses its 
thickness and expands into a plate of the usual triangular form, the posterior apex of 
which is seen on the left side behind the two overlying sacral ribs, stretching as far 
back as the ilium (ib., 62 ) ; from this apex, or angle, to the acetabular junction with the 
pubis, the ischium measures 8 inches. Pyritic matter intervenes between the ischium 
and sacral ribs, on the left side. 
So much of the pubis (Tab. IX, 64 ) as is visible on the left side exhibits the usual 
subcircular discoid shape, with the two facets on the thickened part of the margin, one 
for articulation with the ischium, the other completing the fore part of the acetabular 
tract. The broadest part of the exposed pubic disk measures 6 inches lengthwise. 
The femur (Tab. IX, 65 ) is 9 inches 9 lines in length. A longitudinal notch 
feebly marks out a trochanteric part of the thick, convex, articular head; this is 
coarsely pitted for the ligamentous insertions. The shaft contracts, chiefly losing 
thickness, and becoming lamelliform as it expands in breadth to the distal articular 
surface. This is convex, curving in a greater degree at its hinder part. Both anterior 
and posterior borders of the shaft are concave ; the former least so, but to that extent 
differentiating the femur from the humerus, in which it is straight, or rather convex. 
