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DR. J. E. GRAY ON THE GENUS OCADIA. [Feb. 4, 



side produced into a conical prominence in the middle in front ; the 

 edge on the inner side is sharp, and not so much raised, but united 

 in front, and forms a well-marked central longitudinal ridge, which is 

 rather broader behind. 



Skull of Ocadia sinensis. 



There can be no doubt that this genus should be referred to the 

 Kachugina, the second section of Bataguridce, but that it is rather an 

 aberrant form, both in the colouring of the animal and of the shell, 

 especially in the young state, when it has ocellated marks on the 

 margin like the Emydidce, which become solid black spots in the 

 adult shell. In some respects the skull is like that of Hardella ; but 

 there is no central groove between the front of the inner marginal 

 keels of the alveolar surface, found in all the other genera of the tribe. 



There is in the British Museum a fine adult shell of this species, 

 brought home by Mr. Swinhoe, and showing its full development. 

 It has the front and, especially, the hinder aperture of the shell con- 

 tracted, with an internal compressed rib something like those in the 

 larger Batagurs. The vertebral shields have a distinct central keel, 

 interrupted before the hinder edge of each shield. The keel on the 

 anterior shield is very broad, and becomes gradually less broad on 

 the hinder shields, that of the fourth and fifth being narrow and 

 compressed. There is a blunt keel near the upper edge of each 

 costal shield, which is generally of a pale colour, the one on the 

 hinder costal shields being more like a tubercle than a keel. 



