1873.] DR. J. E. GRAY ON THE TRIONYCHID.E. 51 



The skull of a young species, tapering in front, the palatine groove 

 rather wide, narrower behind. The lower jaw very broad in front, with 

 a broad central longitudinal groove, nearly reaching the front edge, 

 and a wide longitudinal groove on the inner part of the sides, with a 

 narrow well-raised edge on the inner side. 



The history of this species, and the account of the specimens in 

 the Museum, is given in my paper on Indian Mud-tortoises in the 

 Ann. & Mag. N. Hist. 1872, x. p. 336. 



6. Trionyx ocellatus. 



Only known young ; callosities not developed ; nose before the 

 eyes with a broad lunate yellow spot. 



Testudo ocellatus, B. Hamilton, icon. ined. 



Trionyx ocellatus, Gray, 111. Ind. Zool. (copy of Hamilton); Gray, 

 Ann. & Mag. N. Hist. 1872, p. 337. 



Gymnopus ocellatus, Dumeril & Bibr., Erpet. Gen. iv. p. 9 ? 



Hab. India. B.M. 



For the history of this species I refer to my paper in the Ami. 

 & Mag. N. Hist. 1872, x. p. 337. 



7. Trionyx bellii. 



Only known from young ; callosities not developed ; upper part 

 of the head black, white-spotted on the crown, with a red spot on 

 the side of the temple and on the angle of the mouth. 



"Trionyx gangeticus, Cuvier," Bell's MS. ; Gray, ' Tortoises, Ter- 

 rapins, and Turtles,' p. 11, tab. 51. 



Trionyx bellii, Gray, Ann. & Mag. N. Hist. 1872, x. p. 337. 



Hab. Asia. 



Only known from Mr. Bell's figure. See observation on it and 

 on Trionyx stellatus japonicus in the Ann. & Mag. N. Hist. 1872, x. 

 p. 337. 



4. ISOLA. 



Palate of the skull with a broad shallow concavity to the internal 

 nostrils, which is rather wider behind. 



The skull of the head obtained from Mr. Theobald is rather elon- 

 gate (4 inches long) ; the nose rather tapers on the side, and is 

 rounded in front ; nose at the eyes about two thirds the width of the 

 orbit ; the groove in front of the palate rather wide, shallow in 

 front, gradually wider and deeper behind ; the upper edge of the 

 lower jaw flat behind, rather wider in front, and more concave, with 

 a deep oblong impression on each side of the well-marked keel, which 

 occupies more than half of the middle of the front end. 



This skull is peculiar for the central palatine groove before the 

 nostrils not being so wide as in Trionyx, and in being rather wider 

 and much deeper before than behind. 



1. Isola peguensis. (Fig. 5, p. 52.) B.M. 



Head pale olive above, minutely and closely punctate with black. 

 Lips and beneath whitish. 



