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



dorsal fins seem to be of ver)^ great importance ; in some species {e.g., P. schlegelii) the 

 first dorsal is much nearer the pelvic fins than it is in others {e.g., R. gramdatns). 

 As regards the freedom or otherwise of the anterior border of the pectoral, I fail to 

 see any absolute difterence at all in fresh or well-preserved specimens. Undoubt- 

 edly, however, there is a certain gradation in respect o_f this character ; in R. djed- 

 densis the fin projects more freely than it does in R. granulatus, but in R. granulatus 

 it projects more freely than in R. halavi. The fact that the lower lobe of the caudal 

 is distinct in A', djeddcnsis and not so in the other species would not be regarded as a 

 generic difference in other families of the suborder. Indeed, " Rhynchobcdus " seems 

 to me to be less widely separated from such a form as Rhinohatis granulatus than 

 Pristis cuspidatus is from such a form as P. perottetii. 



Key to the Iiidinii Species of Rhinobatis. 



I. Anterior dorsal fin above pelvic fins. Tail with a distinct lower pointed 

 lobe . . . . . . . . . . R. djeddensis. 



II. Anterior dorsal fin wholly behind the pelvic fins. 



A. No fold of skin on the interval between the anterior angles of the 



nostrils. 

 A'. Interval between the posterior angles of the nostrils not markedly 

 less than the length of one nostril. 

 {a) A ro-w of sharjj s]3ines running down the centre of the back. 

 Snout acutely pointed . . . . R. granulatus. 



[a') An interrupted row of obtuse spines on the back. vSnout 

 obtuse . . . . . . . . R. halavi. 



A". Interval between the nostrils posteriorly less than half the length 

 of one nostril . . . . . . R. thouini . 



B. The anterior nasal valve on each side continued as a fold of skin extend- 



ing towards the other nostril. 



(b) Back with a median row of large, .smooth tubercles crossed by a 



vertical line of similar tubercles on the .shoulder R. columnce. 



(//) Back finely granular with faint indications of a mid-dorsal 



row of enlarged tubercles . . . • R- schlegelii. 



Of the six species enumerated in this key four have been taken by the ' ' Golden 

 Crown , ' ' while a fifth is fairly well represented in the old collection of the Indian Museum. 

 I have not seen R. thouini. R. schlegelii is here recorded from Indian seas for the first 

 time ; R. djeddensis has been taken in very large numbers, while R. granulatus is rep- 

 resented by a single specimen in the ' ' Golden Crown ' ' collection and by several in that 

 of the Indian Museum ; of R. columnce several s])ecimens have been taken by the trawler. 



6. Rhinohatis djeddeiisi'^ (Forskal). 

 Rhyneholjatus djeddensis, Gunther , op. cit., p. 441 ; Day, op. cU., p. 40. 

 Snout pointed, measured from the mouth between \ and J of the total length ; the 

 concavity on the dorsal surface extending forwards for a considerable distance. 



