270 
PROCEEDINGS OF SOCIETIES. 
structure, and showed the singular compound character of its skull, which com-* 
bines the cranium of a Lizard with the jaws of a Porpoise, armed with the teeth 
of a Crocodile, and described the series of bony plates which surrounded the 
sclerotic coat of the immense eye of that creature, and stated that he had first 
described their affinities to the sclerotic plates of Tortoises and Iguanas and other 
reptiles, and their use in the mechanism of the organ of vision, adapting that 
wonderful instrument to receive the rays of light through media of varied density, 
in a lecture he delivered upwards of two years ago before the members of this 
Institution, a full report of which was contained in the Cheltenham Chronicle of 
the 10th of December, 1835. He thought it was but justice to himself to be 
somewhat particular about dates, as Dr. Buckland had received a vast deal of 
credit for having pointed out, by a similar train of reasoning, the probable uses of 
the plates. The lecture alluded to was delivered upwards of twelve months anterior 
to the publication of the Doctor s treatise, and if merit was due to any one it was 
assuredly due to him (Mr. Wright). The mechanism of the spine was next 
described, and the singular character of the vertebrae compared with those of 
fishes, which they most closely resembled. The disposition of the several pro¬ 
cesses was viewed in reference to the aquatic habits of the animal, and the 
evidence of prospective design which the entire column afforded clearly pointed 
out. The form of the thorax and the disposition of the ribs next engaged the 
lecturers attention, and he gave a luminous exposition of the wonderful me¬ 
chanism of the extremities, and showed by numerous examples that the paddle 
of the Ichthyosaurus, which at first sight so closely resembled a tesselated pave¬ 
ment, was composed of precisely the same elements that we recognize in the 
human arm, fore-arm, and hand, and so far from being a monstrous production, 
affords a fine example of that harmony of composition which we everywhere 
discover in the mechanism of organic forms. The entire structure of this wonder¬ 
ful reptile showed that it was admirably adapted for swimming with great 
rapidity through the sea, and from the armature of its jaws, that it was highly 
carnivorous in its habits. From the demonstration of its skeleton the lecturer 
proceeded to describe the probable character of its digestive organs, which from 
the form of the petrified contents of the intestinal canal, called coprolites , found 
with its shattered skeleton, were conjectured to resemble that of the Dog-fish. 
This opinion was founded on the fact that some coprolites presented a peculiar 
spiral form, which was supposed to be occasioned by the inner membrane of the 
canal in which they were contained being provided with a spiral valve, like 
the spiral valve of the Dog-fish, or the corkscrew disposition of that canal in the 
Sword-fish. 
The Plesiosaurus was described as a creature which approached existing Lizards 
still more closely than the preceding; it was distinguished from all other animals 
