364 FAUNA ANTIQUA SIVALENSIS. 



large as tliat 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 and greater rotation, and that the Co- 

 lossochelys 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 sheU and extremi- 

 ties 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 youjig or half-grown Colosso- 

 chelys, was exhibited. The head of the adult to correspond 

 with the dimensions of the shell, and according to the pro- 

 portions furnished by a large Testudo Indica, was deduced to 

 have been two feet long. 



There were no ascertained cervical vertebrae to afford 

 direct evidence as to the length of the neck, which was con- 

 structed in the diagram relatively to the proportions of 

 Testudo Indica. The entire length of the Colossochelys Atlas 

 was uif erred to have been about eighteen feet,^ and it was 

 believed to have stood upwards of seven feet high. 



The generic name given by the discoverers has reference to 

 the colossal size of the fossil {koXoo-ctos et ')(^s\vs), and tlie 

 specific one to its fitting re]3resentation of the mythological 

 tortoise that sustained the world, according to the systems of 

 Indian cosmogony. 



The anatomical details occupied so much of the evening, 

 that space was not left for Dr. Falconer to enter on general 

 points connected with the fossil, such as its possible con- 

 nection with the mythological fables of the Hindoos and the 

 sera of its extinction, which will form the subject of another 

 communication. 



The results of a chemical analysis of the bones by Mr. 

 Middleton were communicated, showing that they contained 

 a very large quantity of fluorine. Some rough sketches of 

 the Colossochelys were exhibited, etched on glass by means of 

 the fluorine yielded by its own bones. The analysis indicated 

 the presence of 11 per cent, of fluoride of calcium. 



Part II. 



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 modi- 

 fications of form through the costal elements of the carapace 

 and the dorsal vertebrse, all of which bear the closest resem- 

 blance to the ordinary type of the Chersite Chelonians, or 



' See note, p. 363.— [Ed.] 





