1873.] DR. J. E. GRAY ON THE TRIONYCHIDjE. 49 



the front odd bone of the dorsal disk is quite separate, with a trans- 

 verse oblong pitted callosity ; the front margin of the dorsal disk 

 has a central prominence nearly reaching the back edge of the odd 

 bone. 



In young specimens the odd bone in the front of the dorsal disk 

 is transversely elongate, rugose the whole of its width, separate from 

 but very close to a central prominence in front of the dorsal disk. 



2. Trionyx leithii. The Poonah Mud-tortoise. (Fig. 3, p. 48.) 

 A small species, the shell about 10 inches long and 61 broad ; the 



alveolar surface of the lower jaw nearly flat, with a very slight lon- 

 gitudinal ridge across the front end. 



Trionyx leithii, Gray, Ann. & Mag. N. H. 1872, x. p. 334. 



Hub. Poonah, Dr. Leith. 



The history of this species is given in the Aun. & Mag. N. H. 1872, 

 x. p. 334. 



There are two other specimens in the British Museum, from Mr. 

 Day. The older one has the dorsal disk suborbicular, concavely 

 truncated behind. The odd bone in front about half the width of 

 the widest part of the dorsal disk, and united to it. 



The younger one has the dorsal disk with numerous, close, rather 

 irregular, minute tubercles ; the hinder edge is regularly arched ; 

 the front edge truncate, with a deep arched notch on each side of 

 the central prominence ; the odd marginal bone is rather broad, 

 arched in front, and slightly concave on the sides of the inner edge, 

 about I as wide as the breadth of the broadest part of the disk. 



** The hinder part of the crown and sides of the head marked 



with pale spots. 



3. Trionyx hurum. The " Kaavez." 



Crown of the head varied with irregular black lines ; a yellow spot 

 on each side of the crown and at the back angle of the mouth. 



Kaavez, Hardwicke, icon. ined. B. M. 



Trionyx hurum, Gray, Synopsis Rept. tab. 1 0, copy of Hardwicke ; 

 Grav, 111. Lid. Zool. tab., copy of Hamilton's ; Gray, Ann. & Mag. 

 N. Hist. 1872, x. p. 335. 



Testudo htirum, Hamilton, icon. ined. 



The history of this large species is to be found in the Ann. & Mag. 

 N. Hist. 1872, x. p. 336. 



4. Trionyx jeudii. 



Skull, with nose rather elongate, produced forward, with a rather 

 tapering outline ; orbit further from the cavity of the nostrils than 

 the diameter of the orbit ; alveolar surface of the lower jaw with a 

 very distinct central longitudinal ridge in front, with a deep pit on 

 each side. 



Trionyx jeudii, Gray, P. Z. S. 1869, p. 217, fig. 19 ; Suppl. Cat. 

 Sh. Rept. p. 97, fig. 32 (skull). 



Hub. India. 



Proc. Zool. Soc— 1873, No. IV. 4 ' 



