1909.] 



N. Annandai,e : Report on the Batoidei. 



ten times as distant from one another at the base as they are at the tip of the saw. 

 They frequently have the same nmnber on the two sides of the saw. The posterior 

 dorsal fin is usually rather larger than the anterior one. There is a narrow yel- 

 lowish streak along the side of the saw in large individuals of this species, as there 

 is in all adult specimens of P. pectinatus, but even in the males the colours 

 are dull. 



Day says that P. zysron is perhaps more common in the seas of India than P. cus- 

 pidatus , but this remark probably applies to the Arabian Sea rather than the Bay of 

 Bengal. Several large specimens have, however, been taken by the " Golden Crown.' ' 

 The measurements of two males are as follows : — 



Total length (including saw) . . . . .. 456-0 cm. 



I^ength of saw 

 ■ Width of saw at base 



,, ,, ,, ,, tip 

 Breadth across pelvic fin 



127-9 , 



12-5 , 



6-25 , 



1.317 > 



402-5 cm. 



120-0 



26-3 



12-5 



131-2 



The second of these specimens has 28 pairs of rostral teeth, the first has 25 on one 

 side and 26 on the other. I should not be surprised ultimately to obtain a series of 

 specimens linking P. pedinatus and P. zysron together. Undoubtedly there has been 

 much confusion as regards the two species, and I am by no means satisfied that thev 

 are distinct. The large size of adult specimens and the difficulty with which they are 

 preserved, however, militate against the acquisition of such a series. All the ordinary- 

 specimens of P. pedinatus I have seen have been less than 10 feet long with the saw, 

 while the two of P. zysron I have examined in detail have been over 15 feet. I doubt 

 whether either form grows as large as P. perottetii. 



Family RHINOBATID^ (Guitar-Fishes, Spear-Sharks). 



Shark-like rays (having the gills on the ventral surface) with the anterior part of the 

 body depressed but comparatively little expanded and the pectoral fin-rays not 

 extending forwards to the sides of the head. The snout rounded or produced, 

 without rostral teeth. No electric organ. Two dorsal fins, without spines. 

 This family is divided by Günther, as by most other ichthyologists, into three 

 genera, viz., Rhy'nchobatus , Rhinobatus and Trygonorhina. Trygonorhina , which is 

 distinguished from Rhinobatus by having the anterior nasal valves confluent, is only 

 known from the S. Pacific, but Rhynchobatus and Rhinobatus are both well represented 

 in Indian seas. Two very dissimilar species, however, are held by most authors to 

 constitute the former genus, although they differ from one another considerably not 

 only in the shape of the snout but also in the structure of the head. These two species 

 are R. ancylostormis and R. djeddensis. The former in my opinion is not congeneric 

 with the latter and as Gill's generic name Rhamphobatis is available for it, I have placed 

 it in that genus. As regards R. djeddensis, moreover, I have been confronted with a 

 difficulty in the matter of the proper genus to which it should be assigned. It is sup- 

 posed to be distinguished from the species of Rhinobatus by certain rather ill-defined 



