140 Memoirs of the Indian Museum. [Voi,. II, 



Suborder Batoidei. 



Family RAIID^. 



Rata andamanica , sp. nov. 



Illusir. Zool. "Investigator," Fishes, pi. xlvi, fig. 2 (1909). 



Raia, sp. nov., Annandale , Mem. Ind. Mus., ii, part i, p. 3. 



The breadth of the disk is slightly greater than the length measured to the end 

 of the pelvic fin in the proportion of 19 to 17. The tail is long, the distance between 

 the tip of the tail and the centre of the vent is much greater than the distance 

 between the snout and the vent in the proportion of 3 to 2. 



The snout projects very slightly. The antero-lateral borders, which are markedly 

 sinuous, meet at less than a right angle. The lateral and posterior angles are both 

 evenly rounded, but the lateral angle is less broadly rounded than the posterior. The 

 greatest diameter of the eye is slightly greater than the smallest interorbital distance, 

 and is a quarter of the length of the snout measured from the centre of the upper jaw. 

 The spiracle is close behind the eye ; its greatest diameter is about half that of the 

 eye. The mouth is nearly a transverse line, being very slightly curved ; its length is 

 one-third that of the snout. The anterior limit of the nostril is removed from the 

 corner of the mouth by a distance equal to the breadth of the mouth. There are 54 

 rows of teeth in the upper jaw, 40 in the lower. The teeth are on an oval base ; the 

 front ones are worn flat, the back ones have a low pointed cusp. 



The dorsal fins are small, the anterior being somewhat larger than the posterior; 

 they are close to the end of the tail and are separated by a distance less than the 

 length of the base of either. The caudal fin is only represented by a narrow fold of 

 skin on the lower side. 



There is a continuous row of eight large thorns on the supraorbital ridge ; the 

 first of these is in front of the eye, the last behind it. 



There are about 15 large spines over the rostral cartilage which does not extend 

 quite to the end of the disk. . 



There is a single series of large spines in the mid dorsal line extending from a short 

 distance behind the level of the spiracles, to the tail, where the series becomes less 

 regular. Besides this, most of the upper surface except the postero-lateral margins of 

 the pectoral fins is covered with small denticles. 



The sides and top of the tail are spiny, the spines being larger on the upper 

 surface. 



The entire lower surface is smooth and naked except the distal half of the tail, 

 which bears a few very small spines. 



Colour, a uniform slaty grey above and below. 



A small male 21 cm. in length from 279 fathoms in the Andaman Sea, Station 

 332. Registered No. F i\^^. 



