280 DR. F. DAY ON INDIAN FRESHWATER FISHES. [May N, 



survive even longer, as when it had been seven hours out of water 

 it was opened, and the heart was found still pulsating, although the 

 body was as hard and stiff as a piece of board from the mucus 

 which had exuded and dried over it. A specimen of the 0. striatiia, 

 18 inches long, was wrapped up alive in a dry cloth and locked in 

 a close cupboard, where it lived for 16 hours. 



Experiment No. 10. — As these fishes had been proved to live for 

 some time altogether without water, and again in water when unable 

 to pass it through their gills, it appeared probable that the inhala- 

 tion of chloroform would affect them. Therefore, at 9.30 a.m. an 

 Ophioeephalus striatus, of upwards of a foot in length, was placed in 

 the glass globe of a hanging lamp, the top of which was covered over 

 by a thick towel ; ten drops of chloroform were then administered, 

 and repeated every minute for five doses. After half a minute the 

 fish made snatches at the air several times in succession, after which 

 it remained in a quiescent state for four and a half minutes, when, 

 after the last ten drops had been administered, it became very 

 excited, and sprang about as if greatly distressed. But it soon sank 

 down, and rapidly became more and more comatose, until at the end 

 of thirteen minutes from the commencement of the experiment it 

 was in a perfectly motionless state, and in that condition was thrown 

 into a tub of cold water, the fluid being only two inches deeper than 

 the height of the body of the fish lying flat. Here it remained on 

 its side (only jumping up once), giving out bubbles of air, and 

 moving its pectoral fins backwards and forwards, at first rapidly and 

 then gradually slower and slower, until its death, which occurred 

 27g minutes from the commencement of the experiment. There 

 was no movement of the gills whatever ; and immediately after death 

 the chest was opened, and the heart was not found pulsating, but 

 full of very dark blood ; on being touched it contracted sluggishly. 



Experiment No. 1 1 . — Wishing to collect some of the air con- 

 tained in these receptacles, a specimen was held under water, and by 

 means of pressure on the superior branchiae all the air was dis- 

 charged. Each time the operation was repeated the fish, immediately 

 on being released, ascended to the top and took in a fresh supply of 

 air ; and the same thing occurred when it was held in the hand and 

 lifted out of the water. In each instance after this aerial respiration 

 air was found in the previously emptied cavities. When these fish 

 are feeding, small bubbles of air are almost invariably discharged 

 through the mouth, probably from the cavity, each time they swallow, 

 and they arise almost immediately to inhale more. 



Experiment No. 1 2. — A number of these fishes were placed in a tub 

 with a small amount of water and plenty of common grass. No 

 other food was allowed them ; but at the end of three weeks they 

 were perfectly well and lively. 



Before drawing attention to the conclusions to be deduced from 

 these phenomena, it may be as well to refer briefly to the opinions 

 previously advanced by others, Commerson considered the laby- 

 rinthiform cavity in the Osphromenus intended for the purposes 

 of smell, and therefore named it Osphromenus, and the species was 



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