On the gigantic Fossil Tortoiscy Colossochelys Atlas. 533 



at the apex, and supplied with a thick cuneiform keel on its inferior 

 side : this keel constitutes one of the principal features in the fossil. 

 The entosternal portion exhibits exactly the form of Testudo, the 

 same being the case with the xiphiosternal or posterior portion. The 

 plastron in the adult animal was estimated to be nine feet four 

 inches long. 



The carapace or buckler of the shell coincides exactly with the 

 general form of the large land-tortoises, of which it exhibits only a 

 magnified representation, flattened at the top and vertical at the sides, 

 with the same outline and recurved margin. The shell was estimated 

 to have been twelve feet three inches long, eight feet in diameter, 

 and six feet high. 



The extremities were described as constructed exactly as in the 

 land-tortoises, in which the form of the femur and humerus is marked 

 by peculiar characters. These bones in the fossil were of a huge 

 size, corresponding to the dimensions of the shell. Tlie ungueal 

 bones indicated a foot as large as that of the largest Rhinoceros. The 

 humerus was more curved, and the articulating head more globular 

 and deeper in the fossil, from which it was inferred that it had a 

 stronger articulation, greater rotation, and that the Colossochelys 

 was enabled to bring its anterior extremities more under its weight 

 than is the case with existing tortoises. 



The affinities with Testudo shown in the shell and extremities were 

 found to hold equally good in the construction of the head, of which 

 a comparatively small-sized specimen, inferred to have belonged to 

 a young or half-grown Colossochelys, was exhibited. The head of 

 the adult to correspond w-ith the dimensions of the shell, and accord- 

 ing to the proportions furnished by a large Testudo Indica, was de- 

 duced to liave been two feet long. 



There were no ascertained cervical vertebrae to afford direct evi- 

 dence as to the length of the neck, which was constructed in the 

 diagram relatively to the proportions of Testudo Indica. The entire 

 length of the Colossochelys Atlas was inferred to have been about 

 eighteen feet, and that it stood upwards of seven feet high. 



The generic name given by the discoverers has reference to the 

 colossal size of the fossil (kij\o(T(tus et j^eAus), and the specific one to 

 its fitting representation of the mythological tortoise that sustained 

 the world, according to the systems of Indian cosmogony. 



May 14. — The conclusion of the paper by Dr. Falconer and Cap- 

 tain Cautley on the Gigantic Fossil Tortoise of India was then read : — 



" On a former meeting we went through the anatomical characters 

 presented by the remains of the Colossochelys Atlas. Commencing 

 with the plastron, we traced the modifications of form through the 

 costal elements of the carapace and the dorsal vertebrae, all of which 

 bear the closest resemblance to the ordinary type of the Chersite Che- 

 lonians, or true land tortoises. A like result followed the examina- 

 tion of the extremities, which, as exhibited in the remains of the 

 humerus, femur and ungueal phalanges, were seen to be constructed 

 exactly on the plan of Testudo, with columnar legs and truncated 

 club-shaped feet, as in the proboscidean Pachydermata. The same 



