720 EEPTILIA. 



conforms more to the Emys type than to that of Geoemyda, and the skulls, in the 

 presence of a quadrate- jugal, agree with Emys. 



There is nothing in the features of the internal anatomy of these forms that 

 would entitle us to separate them from the Emydes. They are all provided with 

 cloacal bladders, but to a varying degree. In G. grandis the bladders are very large, 

 and the whole of their inner surfaces are covered with dendritic papillse. In 

 G. depressa they are small, and also in C. theohaldi, but I am unable to speak of 

 these structures in C. tricar inata^ having never had the opportunity to examine a 

 fresh example of that species. In the genus Hmys they are large and generally 

 smooth. 



The presence of cloacal bladders indicates that all of these animals have one 

 habit, and in this respect they must be regarded as belonging to the Emydidce, and 

 the males, as in the Emydes, have a more or less concave sternum, but these 

 structures are not present in the so-called genus Manouria nor in the Testudinidce 

 generally. 



In Geoemyda grandis the toes of the fore feet are webbed to the base of the 

 claws, but not broadly so, and the hind toes are hardly perceptibly webbed, while in 

 G. depressa the web, at the base of the toes, in the hind foot, is still more obscure. 

 In Emys both feet are webbed, but the even partial webbing in these two forms 

 referred to Geoemyda, serves to connect them with Emys. 



In Chaibassia tricarinata the toes seem to have been in much the same con- 

 dition as in C theohaldi, in which no web can be said to exist. 



As there can hardly now be any doubt regarding the natural family to which 

 these four species rightly belong, the question arises what value is to be attached 

 to the absence in the skulls of G. grandis and G. depressa of a quadrate- jugal 

 bone. Besides this feature, which separates the latter from the true Emydes, their 

 skulls, although conforming in their alveolar palatine characters and large palatine 

 foramina to the Emyde type, differ from it in the great breadth of the fronto-nasal 

 region. But viewing their structure as a whole, they appear to me to be entitled to 

 generic rank among the Emydidce. 



The Emyde which Mr. Theobald has placed in the new sub- genus Chaibassia 

 subordinate to Geoemyda should, by the structure of its skull, be more properly 

 considered as sub- generic to the genus Emys, because its whole form above and 

 below, its more elongated character generally, and the presence of a quadrato-jugal, 

 show it to be closely allied to Emys, indeed so much so, that, judging by the skull 

 alone, one would not be justified in separating it generically from Emys. There is, 

 however, a feature observable in Blyth's type of 0. tricarinata, and in another of 

 the same species which I procured from Chota Nagpur, through the valued assistance 

 of Colonel Dalton, C.S.I., which would seem to indicate a tendency in this form to 

 diverge towards the members of the family Cistudinidce. It is this, that the process 

 from the hyposternal piece which springs upward and abuts against the first costal 

 and third marginal plates, does not become firmly attached to the latter, but is 

 movable on it, and this false joint involves apparently the side of the hyposternal, but 

 does not extend forward to the hyosternal. This is observable in the male type of 



