110 REPORT — 1841. 



occiput to the beginning of the tail. In Crocodiles the skull equals about 12 

 dorsal vertebrae 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 probabl)- not below the length of the head of the Megalosaur. 

 With regard to the tail, this includes between 36 and 38 vertebras in Croco- 

 dilians, 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 pre- 

 sented 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 Megalo- 

 saur to have had the same number of vertebrae as the Crocodile, and multi- 

 plying 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, 



Length of head B feet. 



Length of trunk, with sacrum 12 — 



Length of tail 13 — 



Total length of the Megalosaurus 30 — 



Upon this mode of obtaining an idea of the bulk of the present extinct rep- 

 tile 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. 



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

 found in the Bath oolite immediately below that slate, and in the cornbrash 

 above it. The other formation in which the remains of the Megalosaur 

 occur, next in importance to the Stonesfield slate, is the Wealden strata. 

 Dr. Mantell has discovered in the ferruginous clay of the Forest of Tilgate 

 a fine vertebra, and a portion of the femur of the Megalosaurus, 22 inches 

 in circumference. Many teeth have been discovered altogether of the same 

 form as those found by Dr. Buckland. Some fragments of the metacarpus 

 and metatarsus from this locality, were thicker than those of a large hippo- 

 potamus. Mr. Holmes, surgeon at Horsham, possesses a good caudal ver- 

 tebra, and some other parts of the Megalosaurus from the ferruginous sand 

 near Cuckfield in Sussex. Remains of the Megalosaurus occur in the Pur- 

 beck limestone at Swanage Bay. In some of the private collections in the 

 town of Malton, Yorkshire, are teeth, unquestionably belonging to the same 

 species as the Stonesfield Megalosaurus, ivoxaihQ oolite in the neighbourhood 

 of that town. 



The tooth from the New Red Sandstone of Warwick figured in the Memoir 

 by Messrs. Murchison and Strickland*, and referred to the Megalosaurus, be- 

 longs to another genus of Lacertian, more nearly allied to the PalcBosaurus 

 of the Bristol conglomerate. 



* Geol. Trans., 2nd Series, vol. v. pi. xxix. fig. 7. 



