i534 Zoological Society i Dr. Falconer ««^ Capt. Cautley 



direction of affinity was observed throughout the conformation of 

 the head. The only portions of the skeleton from which more or less 

 direct evidence was not derived, were the neck and tail vertebrse, of 

 which there were no specimens in the collection. The general re- 

 sult of the examination showed that the Colossochelys Atlas was 

 strictly a land tortoise in every part of its bony frame ; and the im- 

 pressions of the horny scutes proved the like in regard to the arrange- 

 ment of its dermal integument. 



" The principal distinctive characters were found in the sternum, 

 which is enormously thickened at its anterior extremity, along the 

 united portion of the episternal bones, and contracted into a narrow 

 neck, so that the width of the combined episternals does not much 

 exceed their thickness : this thickened portion bears on its under side 

 a deep massive cuneiform keel, which terminates upon the commence- 

 ment of the entosternal piece. There is more or less thickening of 

 this part in all the species of Testudo, and the amount of it is very 

 variable in different individuals of the same species ; but there is 

 nothing approaching the same degree of contraction in reference to 

 the thickness, nor aught like a developed keel, in any of the existing 

 land tortoises which we have either had an opportunity of examining, 

 or seen described in systematic works on the tribe. The keel in the 

 fossil is feebly shown in the young animal, but strongly marked in 

 the adult. Conceiving that generic distinctions are only legitimate 

 in the case of well-defined modifications affecting some of the leading 

 characters in the organization of an animal, we do not consider our- 

 selves warranted in attaching a higher systematic importance to the 

 Colossochelys than as a subgenus of Testudo, which may technically 

 be defined thus (the distinction resting mainly on the form of the 

 sternum) : — 



Subgen. Colossochelys. 



Testa solida, immobilis, sterno antice in collum valdi incrassatum, 

 subtils carind crassd cuneiformi instructum, angustato. Testudo 

 terrestris, statura et mole ingenti (inde nomen KoKoaabs et x^^vs) 

 sui tribus prodigium ! Olim in Indise orientalis provinciis sep- 

 tentrionalibus degebat. 

 •' Colossochelys Atlas. — The first fossil remains of this colossal tor- 

 toise were discovered by us in 1835 in the tertiary strata of the Se- 

 walik Hills, or Sub-Himalayahs skirting the southern foot of the great 

 Himalayah chain. They were found associated with the remains of 

 four extinct species of Mastodon and Elephant, species of Rhinoceros, 

 Hippopotamus, Horse, Anoplotherium, Camel, Giraffe, Sivatherium, 

 and a vast number of other Mammalia, including four or five species of 

 Quadrumana. The Sewalik fauna included also a great number of 

 reptilian forms, such as crocodiles and land and freshwater tortoises. 

 Some of the crocodiles belong to extinct species, but others appear 

 to be absolutely identical with species now living in the rivers of 

 India : we allude in particular to the Crocodilus longirostris, from 

 the existing forms of which we have been unable to detect any dif- 

 ference in heads dug out of the Sewalik Hills. The same result 



