WEALDEN FORMATIONS. 25 



of Java having 27 vertebrae of the trunk, we do not, even calculating the same number 

 of vertebrae to have occupied each a space of five inches in the Megalosaurus, obtain a 

 length of trunk exceeding 1 1 feet 3 inches. 



I should consider the first calculation, or about 10 feet, to have been more nearly 

 the natural length. 



To this we must add 2 feet for the known length of the sacrum. Thus 12 feet 

 will be a fair or even a liberal allowance of length from the occiput to the beginning 

 of the tail. In Crocodiles the skull equals about 12 dorsal vertebras in length. In the 

 Java Monitor the proportion of the head is less. In the Iguana the cranium does not 

 exceed 6 dorsal vertebrae in length. 



We may consider therefore 5 feet, taking the Crocodile as the term of comparison, 

 as probably not below the length of the head of the Megalosaur. With regard to the 

 tail, this includes between 36 and 38 vertebrae in Crocodilians, but varies from 30 to 

 115 in the small existing Lacertians, in many of which it is a prehensile organ, aiding 

 them in climbing and other actions suitable to their size. It is very improbable that 

 the tail should have presented such unusual proportions in the great Saurian under 

 consideration, and indeed very few caudal vertebrae of the Megalosaur have been as 

 yet discovered, and none exceeding 4 inches in length. Allowing the Megalosaur to 

 have had the same number of vertebrae as the Crocodile, and multiplying this number 

 36 by 4|, a length of 12 feet 6 inches is thus obtained for the tail. A calculation on 

 this basis thus gives, in round numbers, — 



Feet. 

 Length of head . . . . . . . . .5 



Length of trunk, with sacrum . . . . . . .12 



Length of tail ......... 13 



Total length of the Meo;alosaurus . . . . . .30 



Upon this mode of obtaining an idea of the bulk of the present extinct reptile I am 

 disposed to place the greatest reliance, and conceive that any error in it is more likely 

 to be on the side of exaggeration than of curtailment. From the size and form of the 

 ribs it is evident that the trunk was broader and deeper in proportion than in modern 

 Saurians, and it was doubtless raised from the ground upon extremities proportionally 

 larger and especially longer, so that the general aspect of the living Megalosaur 

 must have proportionally resembled that of the large terrestrial quadrupeds of the 

 Mammalian class which now tread the earth, and the place of which seems to have 

 been supplied in the oolitic ages by the great reptiles of the extinct Dinosaurian 

 order. 



Strata and Localities of Megalosaurian Remains. 



Besides the Stonesfield slate, the remains of the Megalosaurus have been found in 



4 



