1868.] DR. F. DAY ON INDIAN FRESHWATER FISHES. 2/7 



enclosure, to cut off from the rest of the swamp that portion in 

 which the circular patches had been cleared of sod the night before. 

 This was done by breaking the sod in a narrow line encompassing 

 the space which it was intended to enclose, and trampling a portion 

 of it down to the more solid mud at the bottom. The long grass 

 which is thus carried down makes a kind of fence, which is supposed 

 to confine the fish, but which one can hardly suppose to be very 

 efficacious, as they would have but little difficulty, if so inclined, iii 

 making their way through it. When this is done, the diluted mud 

 in the holes that have been opened overnight is thickened by mixing 

 it with some of the more solid mud, or peat, scooped up from beneath. 

 Some of the long grass which grows on the surface is then laid over 

 the thickened mud in two strata, the stalks of which the one is com- 

 posed being at right angles with those composing the other. The 

 whole is finished off with a coating of mud. Nothing then remains 

 to be done but to watch for the appearance of the fish. The first 

 indication of their presence is the rising of bubbles of air ; and in 

 each instance when these bubbles appeared, the natives who were 

 standing by named correctly the species of fish by which they were 

 emitted, being guided probably by their size and by their coming up 

 singly or in larger numbers. After a bubble of air has appeared 

 but a short time elapses before the head of a fish appears protruding 

 above the surface of the mud. There is no difficulty in securing a 

 fish when he shows himself in this way, as the blades of grass which 

 liave been arranged so as to cross each other beneath the surface of 

 the mud form a net through which he cannot easily force his way 

 back. I remained watching the process for about an hour, during 

 which I saw eleven fish taken, and the natives told me that as the 

 day advanced larger fish would be caught and in greater numbers. 

 None of those I saw taken weie large. They were of three 

 species, Counia {Ophiocephalus kelaarti), Magoora, and Hoonga 

 (Clarias taysmanii). It is obvious that this mode of catching the 

 fish is entirely based upon the fact that they cannot breathe water, 

 but are forced to ascend at stated intervals to the surface to breathe 

 atmospheric air — a fact which I afterwards verified by drowning two 

 or three specimens by inverting a net over them " 



In 1866, when engaged in carrying out my experimental intro- 

 duction of fishes from the plains on to the Neilgherry Hills, my 

 attention was drawn to certain peculiarities in the respiration of the 

 Ophiocephalidae and some other genera ; but it has only been re- 

 cently that I have been enabled to make the following series of ex- 

 periments, which, I trust, may, in conjunction with the preceding 

 observations, assist in elucidating the question of the respiration of at 

 least a few species. In the transportation of the Ophiocephalidse I 

 found that if mud were mixed with the water they did well, but if 

 the water were pure they died. The solution of this is that the 

 muddy water does not pass through their branchiae as they respire 

 air direct, whilst the muddy state of the water decreased the amount 

 of agitation they were subjected to in clear water. 



Experiment No. 1. — Three of the Ophiocephalus punctatus 



