628 Journal of the Asiatic Society of Bengal. [September, 1911. 
discovery of a foetus proves finally that this fish not only 
lives in fresh water very high up above tidal influence but also 
breeds in fresh water—a fact which was denied by Francis Day 
and used to be doubted by many others. 
The bigger species (specimens of which were caught in 
the bed of the Ganges below Bararighat near Bhagalpur) 
may now be recognized as T'rygon fluviatilis, in consequence of 
this form being the larger of the two freshwater species 
alluded to by Buchanan, and having the tail without a hanging 
fold of skin, but provided with spines. 7. fluviatilis occurs 
also in the sea, specimens having been taken by the ‘‘ Golden 
Crown’’ in the Bay of Bengal. The marine specimens were 
received deprived of their tails, but their shape and measure- 
ments at once singled them out as belonging to a hitherto 
undescribed species. Though Hamilton did not provide either 
drawings or descriptions, there is no room for doubt that this 
is the species which he named Raia fluviatilis. 
following measurements will show how closely 
freshwater specimen resembles a marine one in all important 
proportions. The tail of the former is nearly one and a half 
times as long as the length of the disk. The measurements 
quoted are from the specimen from Bhagalpur (which has been 
mounted [F +*3"], and of the marine specimen [F +12°], of 
which the skin has been preserved in spirit. In both cases 
the measurements were taken on the fresh specimen :— 
Specimen from Specimen 
the Bay of from fresh 
Bengal. 
enga water. 
cm. cm. 
Breadth of disk ree 138°75 126°25 
Length of disk 135°0 120-0 
Breadth between eyes a 20:0 16-0 
Length of snout “ 50°0 43-125 
Breadth of mouth a 12°5 11°25 
Length from mouth to vent 83°75 78°75 
Length of tail .. Wanting 176°25 
T’. fluviatilis also breeds freely in fresh water, for young 
ones are caught in the nets in August. 
in numbers in the mud of the bed of the Ganges. T’rygon 
fwiatilis is captured in largest numbers in November (i.¢., 
soon after the subsidence of the floods) and in May, when the 
