104 SPOLIA ZEYLANIOA. 
non-predatory, nest-building species in Ceylon of equal value with 
the lula. The mahseer occurs in up-country rivers (Maskeliya), but 
apparently is not very common in Ceylon; and it is unsuitable 
for tank cultivation, being a migratory river fish of a pronounced 
type. 
It thus appears that there is a distmet scope in Ceylon for the 
cultivation of a non-predatory food-fish, such as the gourami, which 
would fill a gap in the fauna without displacing any native species. 
The recognition of a natural deficiency in the fauna of the inland 
waters of Ceylon is one of the chief practical results of this investi- 
gation, and indicates clearly that the already attempted introduction 
of the gourami should be persevered with. Whenever the fishes 
arrive in Ceylon from abroad they should be carefully acclimatized 
in a Government stock pond, and by no manner of means turned 
loose indiscriminately. When in due course the time comes for 
them to be distributed amongst selected public waters, it would be 
useful to mark them by affixing to the base of the dorsal fin with 
silver wire’ a small silver or aluminium label with a current number 
impressed upon it, the fishes.so marked to be returned to the water 
if by chance they are captured ; and every time they are taken to 
be noted by some arrangement with local headmen. Whatever 
method of marking and recording be adopted, the principle remains 
the same, namely, to effect the introduction systematically and at 
considerable pains. 
EXPLANATION OF THE PLATE. 
Arius falcarius from Angulu Eliya, August, 1909. 
Fig. 1.—Frontal view of ovigerous male, with mouth agape, 
exposing the eggs with their contained embryos in 
the buccal cavity. Note the convexity of the gular 
region. 
Fig. 2.—Embryo lying upon the yellow yolk inside the egg 
membrane, showing the paired efferent vessels of the 
yolk sac. The distal end of the efferent vessel is seen 
in front of the head, below which it enters the heart. 
Very slightly enlarged. 
Fig. 3. 

Lower view of preceding, to show the unpaired efferent 
vessel of the yolk sac. 
Fig. 4.—Embryo (same stage as fig. 2) released from the tough 
elastic egg membrane by puncturing the latter with a 
needle. Total length of embryo about 21 mm. 
