1874.] W. Theobald — On Indian and Burmese species of Triowyx, 77 



the above generalization. Not long since I received a living Trionyx v^rhich 

 fairly corresponded outwardly with the figure of Tr, Jiurum in Gray's 

 Illustrations. This specimen, when prepared, proved (by its skull) to be a 

 true Tr. gangeticus, I then prepared (no specimens existing for compari- 

 son in the Imperial Museum) the skull of a small Triotiyx I had in spirit in. 

 the 'precise livery of Tr. ocellatus, Gray, and this likewise afforded a skull 

 which I should decidedly identify as that of Tr. gangeticus. 



The mandibular symphysis was longer in proportion than in the adult, 

 and in this character it approached the species indicated by Anderson as Tr, 

 7iK/rum, but the convex profile was quite that of Tr. gangeticus. The 

 proportionate length of the head, too, anterior to and posterior to the front 

 rim of the orbit, measuring to the nasal bones, was that of Tr. gangeticus ; 

 in gangeticus the proportion being 1 to 7.70 ; in Tr. stellatus, 1 to 5.90 ; 

 in the young specimen of Tr. ocellatus type, 1 to 7.20. It is moreover 

 incredible to me that all the ocellated specimens one sees should belong to 

 Tr. Imrum, assuredly a rare species, adult in Bengal, and I think therefore 

 that Dr. Anderson has entirely misunderstood the question, and whilst 

 correct in separating the species he terms Tr. liurum from Tr. gangeticus, 

 he is in error as to the differences whereby he distinguishes them, in the 

 young state, and ocellated livery. 



What I believe to be the case is this : — We have in Bengal an extremely 

 abundant and rather variable species, Tr. gangeticus, Cuv., some of the 

 varieties of which have been considered as distinct species by Gray and others, 

 and two of which have lately been re-established under the old name of 

 Jiurum by Dr, Anderson followed by Dr. Gray as described above. In 

 addition to these better known varieties, there is, very rarely met with in 

 Bengal, a second species, confounded by Dr. Anderson with the two so- 

 called species Tr. Tiurum, Gray, and Tr. ocellatus, Gray, the whole being 

 united under the name Tr. liurum, Gray, ajpud Anderson. To this I shall 

 revert presently, but I here give the synonymy of Tr. gangeticus, Cuv., in 

 accordance with the above view. 



Tk. Gangeticus, Cuv. 



Tr. (Testudo) hurum, BucTi. Ham., MSS. 



Tr. (Testudo) gatajhal, BucJi. Sam., MSjS. 



Tr. hurum, Gray, III. I. Z. 



Tr. ocellatus. Gray, III. I. Z. 



Tr. hurum. Gray, Ann. Mag. N. H , Nov. 1872, 331 in part. 



Tr. hurum, Anderson, Ann. Mag, N. H., May 1872, in part. 



This is the common Trionyx of Lower Bengal, and though variable in its 

 markings may be always distinguished from the next by possessing in some 

 form or other the dark streaks and lines on the head at all ages, which the 

 other never does. At page 85 of the Annals and Magazine of Natural 



