33 
1909.] 
N. Annandai.e : Report on the Batoidei. 
Mouth. — The jaws are somewhat curved as a whole and regularly but not very strongly 
undulate. The teeth are small and white ; the transverse ridge is low and 
Pig. 6. — Teeth of Trygon imbricata (enlarged). From preparation in canada balsam. 
somewhat irregular, the surface of the tooth posterior to it being decidedly con- 
cave. There are two short processes on the floor of the mouth, occasionally with 
a minute papilla between them. They are situated much nearer to one another 
than either is to the angle of the mouth. 
At first sight the form described by Bloch and Schneider as Ra'ja imbricata is 
very distinct from Müller and Henle’s Trygon walga. Indeed, so long as I had only 
examined a comparatively small series of specimens, I was prepared to regard them at 
least as distinct varieties.. Recently, however, I have had an opportunity of ex- 
amining a large number of living specimens, among which I find every gradation be- 
tween the two forms. Shortness of tail is not invariably or even usually correlated 
with any peculiarity in the denticles, nor is the exact form of the disk correlated with 
either character. Every possible gradation is found between a distinct caudal fold 
and a complete absence of any such character. Nor is any one peculiarity peculiar to 
either sex. Except that the young has a relatively wider disk, a longer tail and a 
paler colour, and usually fewer denticles on the disk, than the adult, there is no ex- 
ternal difference between them, and I have seen two embryos from one mother which 
differed considerably as regards length of tail. 
T. imbricata appears to be, in the strict sense of the phrase, a littoral and estuarine 
species. Few specimens have been taken in water even so deep as 15 fathoms by the 
“ Golden Crown,” but large numbers are captured in the winter season on the Orissa 
coast at Puri by means of seine-nets worked from the shore. The flesh is only eaten 
by the lowest castes of the Hindus. 
Trygon zugei (Müller and Henle). 
Size small (largest specimen 31 cm. across disk, smallest 8-5 cm.). 
Disk slightly broader than long ; the pectoral angles broadly rounded ; the greatest 
transverse diameter situated about half way between the base of the tail and the 
tip of the snout, which is sharply pointed and much produced, its length from 
the eyes being more than three times as long as the distance between the eyes. 
Eyes nearly as large as the spiracles. 
