46 
FOSSIL REPTILIA OF THE 
They proved to be parts of the Bimorjjhodon macronyx, confirmed many of the 
observations made on previously acquired specimens, corrected others, and added almost 
all that was required for the restoration of the skeleton of this remarkable genus and 
species, which I have accordingly attempted in PI. XX. 
The slab of Lias with the second specimen, including the skull of Bimorpliodon macronyx, 
is of larger size, shows more of the skeleton and in a more separated and definable state 
than in PI. XVII. Nine dorsal vertebrse, third to eleventh inclusive, in natural juxta- 
position, with the twelfth slightly dislocated, are preserved at the upper part of the slab 
(PI. XVm, d). The summits of the neural spines (««) of most of these, and the disposition of 
many of the preserved ribs, show that they lie mainly with the dorsal aspect downward (as the 
specimen is figured). This explains and accords with the position of the parts of the pelvis, 
which lie a little way behind the dorsal vertebrae. The comparatively slender ilium (gg^eg) 
is downward ; the broad ischium (gg), and the pair of spatulate pubic bones (g4), are turned, 
like most of the ribs, upward, as I conclude the abdominal or ventral surface of the trunk 
was directed as the fossil lies in the figured slab. The bones of the hind-limb, in connection 
with the acetabulum, are turned outward, with their inner surface exposed. The projections 
of the trochlear terminations of the metatarsals (i, iv, gg), show that the sole of the foot 
is turned to view. Accordingly, we have here the bones of the left hind limb. On the 
hypothesis that the femur and tibia are seen from the outside, which at first suggests 
itself, they would belong to the right limb, viewed in profile. But then, the broad thin 
plate of bone contributing to the acetabulum, would represent the ilium, and the indi- 
cations of the pelvis below the acetabulum and head of the femur would represent ischium 
and pubis. This interpretation, however, gives to Dimorpliodon proportions of pelvic 
bones very different from those determined by Wagner in Pterodactylus Kochii,^ and by 
Quenstedff in Pterodactylus suevicus ; and, besides, it leaves undetermined the pair of 
bones ( 64 , Pl.XVlII) which closely resemble in form and proportion the ‘pubic bones’ {u, u) in 
Quenstedt’s instructive plate.^ In this plate the ilia («, «) are represented as long slender 
bones, contributing the upper but smaller proportion of the acetabulum, and extending 
horizontally beyond it both forward and backward. The pelvis, in the position in which 
I conclude it to lie in the slab figured in PL XVIII, might well afford such indications of 
the pre- and post-acetabular productions of the ilium as are there shown at 62,62. In 
Pterodactylus suevicus the ischium contributes the lower and major half of the 
acetabulum {tr, loc. cit.), and expands into a broad thin plate (5, ib.), having the pro- 
portions to that of the spatulate pubis, which the bone gs bears to gj, in PI. XVIII. The 
portion of the pelvis in the original specimen being preserved in natural connection with 
1 Wehev Ornithocephalus KochUy in ‘Abhandl. d. math.-pbys. Klasse der Bayeriscben Akad.,’ ii, 
4to, Muncben, 183”. 
® ‘ Ueber Pterodactylus suevicus,' &c., 4to, Tubingen, 1855. 
^ In the Memoir above cited. 
