6454 Fishes. 



throat, as if taking in all the air it can contain, closes the mouth, de- 

 scends under the surface and contracts it throat, as if it were forcing 

 the air into the lungs : sometimes during this action one or two very 

 small bubbles of air are emitted at the gill-aperture, and then the 

 animal takes up its old position near the bottom of the vase. I once 

 saw the animal ascend, and so take in air almost immediately after it 

 had been passing a fresh supply of water to its gills : when I have been 

 observing it, it appeared to take in air more frequently than water. It 

 often rises with its body perpendicular, as if it were going to take in 

 free air, but descends without reaching the surface of the water." 



I will now give some accouut of my own interviews with the mud- 

 fish. These interviews were three in number, and I had the oppor- 

 tunity of examining the creature under two different aspects : on the 

 occasion of one visit, the second, he continually came to the surface, 

 holding his body at an angle of about 45°, keeping his four tendrils in 

 constant and graceful undulation, and frequently opening his mouth, 

 apparently for the purpose of breathing atmospheric air. Although, 

 however, this action was frequently repeated, an idea occurred to me 

 that he might have some other business in hand than merely satisfying 

 his spectators as to what class of endosteate animals he belongs ; 

 because I observed that the gold fishes in his immediate neighbourhood 

 were also hanging from the surface of the water at a similar angle, 

 were also smacking their lips, and were also apparently bent on 

 inhaling atmospheric air. This, instead of inducing me to speculate 

 on the exact site occupied by the mud-fish in the System of Nature, 

 led me to advise the officer on duty to change the water, concluding 

 that mud-fish and gold-fish had combined together to exhaust the 

 oxygen of the small allowance of water in which they were confined. 

 Be this as it may, it is quite clear, that whatever conclusions are drawn 

 from the fact, that one fish in a tank appears to seek a supply of atmos- 

 spheric air, must be applicable to a second, and a third, and a fourth 

 fish, which, under precisely identical circumstances, seek the same 

 means of supporting life. Thus it appears to me that the observations 

 of Mr. Waterhouse Hawkins, Mr. Bartlett and Dr. Gray, coinciding as 

 they do most precisely with my own, go simply to prove that fishes, 

 having exhausted the oxygen of the small portion of water allowed 

 them, seek to obtain that element of existence from the atmospheric 

 air. On the occasion of my other visits, the conduct of the mud-fish 

 was widely different; he kept constantly below the surface, and, with a 

 sort of unhealthy restlessness, perambulated his prison like a caged 

 tiger ; still the movements were free and unfettered ; and the involun- 



