Memoirs of the Indian Museum. 



[Vol. Ill, 



case in fresh specimens. They do not, however, even in a dried skin assume the 

 regular pattern with well-defined outlines so characteristic of T. gerrardii and 

 T. Meeker i. 



The measurements of the disk of the young specimen of T. uarnak given on 

 page 30 of my report are unusual, the disk being broader than is commonly the case. 

 The following measurements were taken from a single batch of somewhat older speci- 

 mens in which the spots had already begun to coalesce and the ground colour of the 

 back to darken: — 



d" cf c? 2 ? 2 ? 



Length of disk 40-0 cm. 3875 cm. 35-0 cm. 37-5 cm. 40-0 cm. 38 75 cm. 4i'25 cm. 

 Breadth of disk 50*0 ,, 47-5 ,, 42-5 ,, 46-25 ,, 50-0 ,, 4875 ,, 51-25 ,, 



Trygon gerrardii, Gray. 

 Mem. Ind. Mus., ii, p. 24. 



Two species are confused under this name in the British Museum Catalogue, a 

 half-grown specimen from Japan being certainly distinct from the types of the 

 species. The latter are young stuffed specimens, but I am pretty sure that they are 

 identical with what I call T. gerrardii} In T. gerrardii the spots never extend 

 to the anterior half of the disk, as they do in the half-grown Japanese specimen, 

 in which there are traces of a mid-dorsal row of spines resembling those of 

 T. akajei. 



A large adult male of T. gerrardii was recently captured off the Madras coast 

 which had the ventral surface suffused with dark pigment. Its measurements were 

 as follows : — 



Breadth of disk . . . . . . . . 86-25 cm. 



I,ength of disk . . . . . . . . 72-5 



I^ength from mouth to vent .. .. .. 4375 ,, 



Breadth between eyes .. .. .. 12-5 ,, 



lycngth of snout . . . . . . . . 7'5 ,, 



This is by far the largest specimen of the species I have seen, but the pale spots, 

 which were confined to the posterior margin of the disk, were quite distinct. 



Trygon ßuviatilis (Ham. Buch.). 



(Plate i, fig. I.) 



Size fairly large (a female from the sea measured 4 ft. 7 J in. across the disk). 

 Disk slightly broader than long without the pelvic fins, very flat, with the lateral 

 angles very broadly and gradually rounded, so that the whole body, including the 



1 But see Dr. Giinther's remarks in his " Fische der Südsee," pt. ix, p. 492 (1910). He is of the 

 opinion that the species of these type specimens cannot be recognized. It is only after comparing large 

 numbers of specimens in different conditions of preservation that I venture to differ from him. 



