Trionyx gangeticus and Trionjx Inirum. 383 



coloration of the specimens yielding skulls identical with the 

 skull figured by Cuvier is very characteristic and uniform, 

 except in very old individuals. The upper surface of the head 

 is uniformly greenish olive, and there is a black line running 

 from between the eyes to the nape, with three pairs of diver- 

 gent stripes on either side of it directed downwards and back- 

 wards. There is no yellowish temporal spot, nor any band 

 across the nose. Young individuals with these characters 

 have greenish-olive shells vermiculated with fine black lines ; 

 and of the large series of specimens that have come under my 

 observation, not one has presented any trace of ocelli. The 

 only change that occurs in the coloration of the ^dult is that 

 the lines on the head become more or less broken up, and the 

 vermiculations on the shell all but disappear. On the other 

 hand, about twenty specimens of Trionyx with the yellow 

 s})0t on the temporal region, and another at the angle of the 

 mouth, with a yellow band across the snout, and with the 

 surface of the head marbled with reticulated black lines over 

 a gi-ound-colour varying in the intensity of its yellow hue, and 

 with the upper shell marked usually with four ocelli, which 

 disappear with age, but of which generally faint traces can be 

 detected in the form of dark spots, have, as I have already 

 stated, skulls quite distinct from Cuvier's T. gangeticus. I 

 propose therefore to retain provisionally for this last-mentioned 

 form Dr. Buchanan Hamilton's name of T. Jiurum^ and for the 

 former T. gangeticus^ Cuvier. 



Dr. Gunther*, in writing of the T.javanicus, Schweigger, 

 as identified by Gray, observes, " that the characteristic mark- 

 ings of the head of the continental specimens are not men- 

 tioned in descriptions of Javan individuals, so that both may 

 be specifically different." Now, however, that T. javanicus 

 of Gray seems unquestionably to be T. gangeticus of Cuvier, 

 may it not be that the " T. gangeticus, Cuvier" of Gray may 

 prove to be T.javanicus, Schweigger. I have never seen T. 

 javanicus in the flesh, nor am I acquainted with its skull ; so 

 that I only throw this out as a suggestion. 



The skull of T. gangeticus, Cuv., as I have now indicated 

 the species, differs from the form 1 provisionally designate T. 

 Iniruvi in its broader and shorter snout — two characters which 

 also distinguish the heads in life. But I shall elsewhere 

 illustrate and describe the two skulls in detail, the sterna, and 

 sexual characters. 



The foregoing identification is an important one, as it opens 

 the way to a more satisfactory understanding of a group by 

 clearing away a load of synonyms. 



* Keplilos of Britiijh ludia, p. If^. 



