408 BRITISH rOSSIL REPTILES. 



than ill PL 15. Nine dorsal vertebrae, third to eleventh inclusive, in natural juxta- 

 position, with the twelfth slightly dislocated, are preserved at the upper part of the slab 

 (PI. 16, d). The summits of the neurals pines (««) 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 (eg^es) 

 is downward ; the broad ischium Q^), and the pair of spatulate pubic bones (cJ, 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> eg), 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 Dimorjiliodon proportions of pelvic 

 bones very different from those determined by Wagner in Pterodacti/lus Kochii} and l)y 

 Quenstedt- in Pterodactylus suevicus ; and, besides, it leaves undetermined the pair of 

 bones (64, PI. 16) 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 PI. 16, might well afford such indications of 

 the lire- and post-acetabular productions of the ilium as are there shown at 03,02- In 

 Pterodactylus suevicus the ischium contributes the lower and major half of the 

 acetabulum {tr, loc. cit.), and expands into a broad thin plate («, ib.), having the pro- 

 portions to that of the spatulate pubis, which the bone 03 bears to c^, in PI. 16. The 

 portion of the pelvis in the original specimen is preserved in natural connection with 

 the sacrum and contiguous vertebrae ; and the constituent bones are rightly recognised by 

 Buckland (op. cit., p. 222). 



It is interesting to note, that the pelvis of Pferosauria, so determined, resembles more 

 closely that of the existing representatives of the section of Pepiilia with the 4-chambered 

 heart and double-jointed ribs, viz., Crocodilia, than it does the pelvis in Chelonia and 

 Lacertia. The ischium in Crocodilia, e. (/., sm-passes the pubis in size, and excludes that 



1 " Ueher Ornitkocep/ialus Kochii," in 'Abhaiidl. d. niatli.-phvs. Klasse der Bayeiischen Akad.," ii, 

 'ito, Munchen, 1837- 



- ' Ueber Pterodactylus suevicus,' &c., 4to, Tubingen, 18.55. 

 ^ In the Jlemoir above cited. 



