232 Records of the Indian Museum. [Vol. XVI, 



The embryo is certainly more advanced than those of either 

 of the two species of Trygon described above, even though it 

 shows a large number of filaments hanging out of the gill-slits. (The 

 branchial filaments, the yolk-sac and the yolk-stalk are not shown 

 in the dorsal view of this specimen, fig. 2). The pectoral fins 

 have developed further on the two sides, but the papilla of the 

 snout separating them is quite distinct. The pectoral and pelvic 

 fins have well developed fin-rays. The claspers are as yet only 

 flap-shaped structures. The tail has a distinct fold of skin forming 

 a fin-membrane. 



The general shape of the body has become more like the rays 

 in that the head does not protrude so much and the bodj' is more 

 depressed to form a flat disc. 



Internal anatomy. — The colon is relatively smaller as is also 

 the rectal gland. The stomach and the duodenum both contain 

 a large quantity of coagulated material of the same nature as in 

 T. kuhlii. The connection of the yolk-stalk with the colon is also 

 similar, 



Pteroplatea poecilura (Shaw), 

 (PI. XIX, figs. 3, 3a.) 



1909. Pteroplatea micnira, Annandale, op. c/t., p. 39. 

 1913. Pteroplatea poecilura, Gartnan, op. cit., pp. 412-413. 



As Garman has shown in the paper cited above the name of 

 this Indian species must be P. poecilura, the name P. micrura 

 being confined to the West Indian form. 



In the single embryo (fig. 3) before us, the lines of union of 

 the pectoral fins with the snout are still indicated and the fins have 

 not as yet met in front. The eyes do not protrude so much, 

 the spiracles (fig. 3a) are comparatively smaller than they are 

 in the younger stages figured by Wood-Mason and Alcock,* and the 

 appearance of the embryo is more like that of the adult. There are 

 no branchial filaments at this stage and the yolk-sac and the 

 yolk-stalk are already absorbed to a very large extent. 



Measurements of a female specimen : — 



Length of disc . . 73 mm. 



Maximum breadth of disc .. 115 mm. 



Interorbital distance . . 14*4 mm. 



Snout . . . . 12 mm. 



Mouth to vent .. .. 5i'2 mm. 



Tail . . . . . . 65 mm. 



Yolk-sac , . . . 6-5 mm. X 4 mm. 



Yolk-stalk . . . , 9 mm. 



There is a single specimen of this stage before us. It was 

 dissected out of a large adult specimen trawled in Portugal Bay, 



1 Proc. Rov. Soc, XLIX, p. 359, pis. vii, viii (1891). 



