Dr. J. E. Gray on Chelonians. 297 



Melanochelys trijuga. 



The skull is at once known from Bellia crassicolUs by the 

 alveolar surface and the sharp simple edge of the lower jaw. 



The shell of this species greatly varies in colour, for 

 example : — 



a. Shell black above, with three yellow keels, more distinct 



when worn. 

 Sternum black, with a well-marked yellow margin ; 



lateral margin of shell yellow. 

 Sternum and shell like the former, but lateral margin with 



irregular pale blotches. 

 Sternum and lateral margin of shell blackish brown. 



b. Back brown, keels not paler. 



Sternum blackish, with a narrow yellow edge. 

 Sternum brown, slightly paler on the edge. 

 Sternum pale bYown, with a broad yellowish border and 

 under margin to the shell. 



In the older specimens the plates become very rugose, of a 

 blackish-brown colour, and often covered with a brown-reddish 

 earth. 



In the younger specimens the first vertebral plate is quadran- 

 gular, about as long as broad, and rather narrower behind than 

 before ; but as the animal enlarges the anterior vertebral plate 

 becomes much longer than broad, and is marked with a line 

 extending up each side of the plate, forming a narrow area 

 behind ; and the upper front margin of the first costal plate 

 overlaps the hinder part of the side of the first vertebral so as 

 to make the plate appear very narrow behind. In a very 

 old solid specimen in the British Museum it has entirely 

 lost the broad square form of its youth, or the elongate 

 urceolate form, partly covered by the overlapping front edge 

 of the first costal, of its more adult age, and become a narrow 

 elongate plate, which is much narrower behind. 



The half-grown have a rhombic space covered with membrane 

 in the middle of the sternum, the centre of it placed rather 

 behind the suture between the pectoral and abdominal plates. 



The dorsal plates of the younger specimens often have tuber- 

 cular radiating lines from the angles of the areola to the 

 margin. 



The young specimens from Ceylon have the edge of the 

 keels and the margin of the shell yellow, like the large spe- 

 cimen from India (/') which I have called Melanochelys Seine • 

 but they appear to pass into the other specimens with the 

 3^ellow on the margin more diffuse. In these young specimens 



