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. Possibh- 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 ' ' oft" the Ganjam coast in 

 23 to 27 fathoms in March, 1909. The type (dried skin, mouth in spirit) is numbered 

 F ^-^,^^ in the Museum registers. 



To facilitate comparison I give the measurements of specimens of the six allied 

 species, Trygon uarnak, Trygon gerrardii, Trygon favus, Trygon bleekcri , Trygon alcockii 

 and Trygon jenkinsii together. The specimen indicated with a * w^as measured in spirit. 



Trygon marginatus , Blyth. (PI. iii, fig. 2.) 



T. marginatus, Blyth, Joiirn. Asiaf. Soc. Bengal, xxix, p. 3S (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 4j times in length of disk. Eyes small. 



Tail much longer than disk , without caudal folds. There is only one large serrated spine. 



Cnlniir. — 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 irregvtlarly 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. 



