172 W. Theobald — On Indian and Burmese Species o/" Trionyx. [August, 



he ascribes to it only four sternal callosities, and where he makes six sternal 

 callosities a generic character of Landemania. Now a fifth callous ' lunate' 

 bone in the sternum is found not only in the present species when fully 

 adult, but in ocellatus (= liurum of Anderson) and Pliayrei, Theob. and is 

 doubtless a generic character of Trionyx though not developed in early life, 

 nor perhaps till extreme age. The sternum of Landemania figured by Gray 

 (in the Sup. Cat. S. R. p. 96) is that of a Trionyx. The animal was not full 

 grown, as may be inferred from the unankylosed suture of the abdominal 

 plates, and the callosity of the lunate bone in front is at that age (as I have 

 seen examples in Gangeticus) being developed from two osculant centres ; 

 though the figure would suggest the idea of the lunate bone being divided by 

 a median suture, which of course it is not, and the idea is unfortunately sup- 

 ported by Gray speaking of these two osculant patches on the lunate bone as 

 a ' sternal pair' in precisely the sense he refers to the abdominal or caudal 

 pairs. This is a mistake, and as far as its sternal characters go Landemania 

 is nothing more nor less than Trionyx. 



Equally open to suspicion are the sternal characters of Aspilus 

 (A. & M. N. H. 1872, Vol. X, p. 339, and Sup. Cat. S. E. p. 101), where 

 the sternal callosities are described as " two lateral." Buch. Hamilton's 

 figure of T. gaiajhol would seem to be answerable for this character, but 

 I cannot help thinking that the two lateral callosities seen in the above 

 figure are no callosities at all, but scars or abrasions accidentally produced, 

 the more so, as the figure is drawn from life, and in the living animal the 

 bony callosities are not apparent but only become visible as the epidermis 

 covering them dries and contracts over them. Dr. Gray, it is true, describes 

 the linear callosities (without figuring them, which is curious) in a Javan 

 specimen of A. cariniferus, but I see no ground for supposing that the scars 

 (as I believe them to be) represented in the drawing of gatajhol represent 

 callosities at all. 



T. Gangeticus is somewhat variable in colour, ranging from dark to pale 

 olive green. The head is symmetrically marked with black diverging lines 

 or with thick black lines, more or less irregular in adults, or in very aged 

 specimens perhaps wanting. The profile of the face is short. The man- 

 dible is armed inside with a median tubercle, hardly developed into a ridge, 

 with a short ridge on either side springing from the inner edge of the jaw 

 and invading for a short distance the masticatory area. 



Sab. — The Ganges valley. Its occurrence east of the Bay of Bengal 

 requires confirmation. 



T. sewaaee, Buch. Ham, 



T. setvaare, Buch. Ham., Icon. ined. {yowuj). 



T. sewaare, Gray, A. & M. N. H. 1872, Vol. X, p. 336. 



T. chhim, Buch. Ham. {adult) Icon, ined (Chim.). 



