34 Memoirs of the Indian Museum. [Vol.. II, 



Skin smooth, richly provided with mucous glands. Sometimes a few rudimentary 

 denticles can be detected on the posterior part of the disk and the base of the tail, 

 but as a rule the skin is naked except for a single mid-dorsal line of large denti- 

 cles with sharp spines directed backwards. Sometimes this line is only developed 

 on the base of the tail, sometimes it extends from a point close behind the 

 spiracles. 



Tail with low dorsal and ventral folds, which commence close behind the spine and 

 run for about a third of the length of the tail ; the tail from one-and-a-half to 

 nearly three times as long as the body. 



Mouth broadly arched as a whole ; the jaws slightly sinuous. The teeth white. Each 



Fig. 7. — Teeth of Trygon zugei, cf " (enlarged). "- From preparation in canada balsam. 



in the male with a roundish base and a long, slender, tapering cusp, which ends 

 in a sharp point ; in the female a triangular ridge takes the place of the cusp. 

 Colour. — Dorsal surface dark blackish brown, no paler at the edge of the fins than on 

 the middle of the disk. Ventral surface white, often blotched or suffused with 

 dark pigment. Young paler above than the adult, with the edges of the pectoral 

 fins black on both surfaces. 



P. zugei does not appear to be common in the northern parts of the Bay of Bengal 

 but a few specimens have been taken by the '' Golden Crown ' ' off the coasts of Burma 

 and Orissa, as well as a considerable number (in February) off that of Madras. 

 The photograph reproduced on plate iv was taken from one of the former while it was 

 still fresh. The freezing to which jt had been subjected, however, had caused the 

 skin to shrivel a little. 



Trygon kuhlii (Müller and Henle). 



Size small (male 30 cm. across the disk, female 32 cm.). 



Disk slightly broader than long : the pectoral angle rounded, the broadest diameter 

 being considerably nearer the tip of the snout than the base of the tail. The snout 



