DR. MANTELL ON THE PELOROSAURUS. 
385 
losaurus and Iguanodon. They belong to a huge terrestrial reptile, in which the 
patellar space is smooth, and not traversed by a deep furrow as in the femur of the 
latter. The structure of these fossils led me to examine with great care the enormous 
femur obtained by Mr. Strickland from the Bradford clay at Enslow Bridge, on the 
Charwell, eight miles from Oxford. This specimen is now affixed to the wall in 
Dr. Buckland’s museum, at a considerable height from the floor, and therefore can- 
not be examined with facility. Unfortunately too the bone was found in so shattered 
a condition that it w'as necessary to cement its anterior face to a board. The poste- 
rior surface pressed flat, the condyles and popliteal space, and the outline of the sides 
of the shaft, are therefore the only characters now displayed ; the proximal extremity 
or head is wanting. This bone exactly corresponds in length and width with the 
humerus of the Pelorosauriis. The condyloid extremity is the only portion in a nor- 
mal state. The condyles (so far as I could ascertain from an elevated and inconve- 
nient position on a ladder) are more equal, and wider apart, than in the Iguanodon 
and Megalosaurus ; but the general appearance of the bone is so similar to that of 
the femur of the Iguanodon when shattered and pressed flat, that until I ascertained 
there were no indications of a median trochanter on the mesial border of the shaft, I 
could not convince myself it did not belong to that reptile. There were no visible 
traces of a medullary cavity, yet it seemed improbable that the shaft of this enormous 
and strong bone could have admitted of the degree of compression it had sustained, 
(for the entire thickness did not appear to exceed 3 or 4 inches,) if it was solid as in 
the Cetiosauri: Dr. Buckland entirely concurred in this opinion. 
To ascertain this important point I wrote to Mr. Strickland, who very obligingly 
favoured me with an immediate reply. In answer to my inquiries, Mr. Strickland 
stated, that upon comparing the femur with that of the Megalosaurus, it was evident 
that it belonged to a different genus : and he had labelled it “ Cetiosaurus” from its 
resemblance to portions of femora and other bones found in the same locality, 
and so named in the Oxford Museum; and likewise, because in the crushed mass 
of bony fibre which filled the interior, he did not perceive any traces of a medullary 
cavity; but it is quite possible, Mr. Strickland adds, ‘'that such a cavity may have 
existed, though now so much obliterated by compression as to have escaped my ob- 
servation.” 
The character of the condyloid extremity, and the general form of this bone, appear 
to me to separate it from the femur of the marine reptiles, to which it has been re- 
ferred, provisionally, by this distinguished naturalist ; if upon a more accurate ex- 
amination a medullary cavity should be detected, there will be strong grounds for 
assigning this gigantic thigh-bone to the Pelorosaurus ; on the contrary, if the shaft 
should prove to be solid throughout, the supposed relation of this femur to the 
humerus previously described, will of course be negatived. 
Summary . — From the facts described he following inferences result: — 
1st. Upon the evidence of the humerus alone, the existence during the Wealden 
MDCCCL. 3 D 
