30 
Memoirs of the Indian Museum. 
[VOL. II, 
This species appears to resemble T. akajei in several respects but to differ in size, 
in the proportions of the disk and tail, lepidosis and character of the teeth and 
jaws. Possibly it may be identical with Bleeker’s Trygon dadong, but on the whole I 
think this improbable. 
Two adult males were taken by the ‘ ‘ Golden Crown ’ ’ off the Ganjam coast in 
23 to 27 fathoms in March, 190g. The type (dried skin, mouth in spirit) is numbered 
F' 2^3 3 Museum registers. 
To facilitate comparison I give the measurements of specimens of the six allied 
species, Trygon uarnak, Trygon gerrardii, Trygon favus, Trygon hleekeri, Trygon alcockii 
and Trygon jenkinsii together. The specimen indicated with a * was measured in spirit. 
Name of species. 
Sex. 
Length 
of 
disk. 
Width 
of 
disk. 
Length 
of 
tail. 
Nasal 
flap. 
Distance 
between 
eyes. 
Snout. 
Trygon uarnak 
3 
I22'5 cm. 
i5o‘0 cm. 
321-25 cm. 
12-75 cm. 
25-0 cm. 
37-5 cm. 
5 » ) > • • 
9 
120-0 ,, 
1525 
438-75 
15-0 ,, 
23-75 .. 
32-5 . 
» > 5 > • • 
9 (juv.) 
2375 ,> 
40-0 ,, 
8o'0 ,, 
2-5 „ 
6-25 ,, 
* 9 (em- 
bryo). 
237 ,> 
29‘5 >1 
67-8 
2-9 M 
4'5 > > 
67 , 
Trygon gerrardii 
9 
55'0 „ 
67-5 ,, 
150-0 ,, 
5-62 ,, 
lo-o 
15-0 ,, 
Trygon favus (type) 
9 
iiS’o >> 
130-0 ,, 
207-5 ,, 
30-0 ,, 
36-25 ., 
Trygon hleekeri 
9 
11875 >, 
Ii7'5 >, 
202-5 M 
8-75 
15-0 ,, 
32-5 ,, 
J 9 9 9 • • 
9 (juv.) 
41 ‘23 ,, 
46-25 ,, 
138-75 >, 
5'0 ,, 
7‘5 >> 
15-0 ,, 
Trygon alcockii (type). . 
g 
73 ’o ,, 
85'o ,, 
102-5 ,, 
7 ’o ,, 
ii-o ,, 
i6'5 ,, 
Trygon jenkinsii 
t? 
7875 
10375 ,, 
IIO-O ,, 
8-75 
16-25 ,, 
22-5 ,, 
„ ,, (type).. 
3 
8o-o ,, 
103-75 ,, 
112-5 
7'5 
15-0 ,, 
20-0 ,, 
Trygon marginatus , Blyth. (PI. iii, fig. 2.) 
T. marginatus, Blyth, Journ. Asiat. Soc. Bengal, xxix, p. 38 (1861) ; Day, Faun. 
Brit. Ind., Fishes, p. 54. 
Disk broader than long, with the pectoral angles somewhat narrowly rounded. The 
snout rounded as a whole, but sometimes with a short terminal projection ; length 
of snout 3f to 4|- times in length of disk. Eyes small. 
T ail much longer than disk, without caudal folds. There is only one large serrated spine. 
Colour .- — Dorsal surface grey, with a distinct blackish tint and without any tinge of 
brown. In the male a series of livid bluish marks of an irregularly crescentic 
outline runs round the disk at some little distance from the margin. Ventral 
.surface white with a broad blackish margin laterally and posteriorly ; this 
margin .sometimes indistinct. Tail blackish. 
