DR. MANTELL ON THE PELOROSAU RUS. 
;^8i 
smoother and more uniform, but as the epiphyses are wanting, and both extremities 
of the bone somewhat abraded by attrition, I am led to conclude that in the recent 
state, the radio-ulnar articulation must have closely resembled the crocodilian type. 
In the posterior aspect (Plate XXI. fig. 1*), the double bend or curve so strikingly 
conspicuous in the shaft of the crocodilian arm-bone, is wanting ; the deltoid ridge 
(Plate XXL fig. P c) commences much lower down, and above the fractured end of 
this process (fig. Pc) the bone expands into the wide flattened head, for articulation 
with the glenoid socket, formed by the union of the coracoid and scapula. Although 
the general character of the fossil corresponds in so many respects with that of the 
Crocodile, yet there are such marked discrepancies, that I have not ventured to in- 
troduce an outline indicative of the probable form of the parts that are deficient ; 
for there is ample space for the commission of important errors in such a substitu- 
tion, which might form a stumbling-block to future observers. 
To facilitate comparison I have subjoined figures of the right humerus of the 
recent Gavial, and of the Iguanodon, and Hylaeosaurus, reduced to an uniform scale: 
the arrn-bone of the Gavial belongs to a skeleton 18 feet long, in the museum of that 
eminent physiologist, my friend Dr. Robert Grant. 
It will be seen at a glance that the enormous bone under consideration differs 
essentially from the humeri of all the Saurians with whose remains it was found 
associated. The large medullary cavity at once separates it from the bones referred 
to the Polyptychodon and Cetiosaurus ; for in these animals the long bones are com- 
posed of “coarse cancellous tissue without any trace of medullary cavity*.” 
These data appear to me sufficient to warrant the establishment of a new genus 
for the colossal air-breathing reptile to which this remarkable humerus belonged, and 
I propose the name of Pelorosaurus'\‘ to indicate the enormous magnitude of the 
original. 
I now pass to the consideration of other parts of the skeleton, or, to express myself 
more correctly, of certain detached and isolated bones found in the same quarry with 
the gigantic humerus, and which, for reasons to be stated in the sequel, may with 
greater probability be assigned to the Pelorosaurua, than to any other of the colossal 
reptiles obtained from the Wealden deposits. 
Anterior Caudal Vertebrae of the Pelorosaurus, Plate XXII. and Plate XXIV. and 
XXV. 
The vertebrse which I would assign to the Pelorosaurus with but little hesitation, 
are four anterior caudals of a very remarkable character, which I found many years 
since in the same stratum as the humerus above described, and at the distance 
of but a few yards. They were firmly imbedded and lying in various positions in a 
* Reports on British Fossil Reptiles, 1841, p. 102. I have a series of bones from Brook in the Isle of Wight, 
through the kindness of my distinguished friend Sir R. I. Murchison, proving the existence of Cetiosauri in 
the Wealden ; all the long bones are destitute of a medullary cavity. 
t IleAwp pelor, monster, unusually gigantic. 
