NOTES AND QUERIES. 181 



aquaria that several species — e.g., flounders, eels, and sticklebacks — thrive 

 as well in one medium as the other, no difference in the aeration of the 

 blood being perceptible. This [being the case, might not any fish be 

 "acclimatised," if one may use the expression, to a similar modification 

 of its native element ? The fact that seals, walruses, and other marine 

 mammals can be kept in fresh water has, of course, as little to do with the 

 matter as that sea-birds will float in a pond; but it seems to me that if 

 this can be proved to be a mere question of gradual habituation, where 

 fishes are concerned, no definite physiological obstacle existing, it will be a 

 subject of importance to those who establish aquaria at a distance from the 

 coast for purposes of study. Sea-vegetation, to the growth of which the 

 marine salts are undoubtedly essential, could be supplied readily enough 

 when necessary. Some years ago I purchased some sea-horses at a port 

 in South America, — nine of them, I think, — aud to my astonishment dis- 

 covered that the vessel in which they had been kept contained fresh water. 

 They had been caught three weeks or a month previously, and I suppose 

 that the nigger who sold them to me had put them into the butt for the 

 simple reason that it was too much trouble to fetch salt water from the 

 shore — though he had a theory on the point wherewith to exculpate him- 

 self. At any rate, he assured me that none had died, and I regard the 

 circumstance that he did not ask payment for any beyond the nine as 

 stronger evidence of the truth of this assertion than anything that science 

 could bring forward. As soon as I obtained possession of them I turned 

 them into a large deck-tub full of sea-water immediately. Two hours later 

 I found two of them dead, and the rest apparently moribund. It would 

 have been very interesting to have worked out the cause of this, for, on 

 such slender testimony as the one case afforded, I could not come positively 

 to the conclusion that it was the salt water which was killing them, but I 

 wanted to save my sea-horses, not to try experiments ; accordingly I 

 removed them from the briny fluid and restored them to fresh. The sick 

 recovered, and reached Paris safely three weeks afterwards. They were 

 there established in a fresh-water aquarium, but unfortunately fell victims 

 to the rapacity of a small crocodile, which escaped from its proper tank one 

 night before the sea-horses had enjoyed their new quarters a week. 

 Sudden chauge of water will of itself often prove fatal to fish. At the 

 Zoological Gardens, Regents Park, I was recently shown some youug dace 

 which had lived in a vase of water which had not been renewed for over 

 two mouths ; they were the survivors of a numerous company which had 

 been repeatedly decimated by previous changes. The other day a gentle- 

 man gave me an account of some sea-anemones which he had imported 

 into one of the midland counties from the Dorsetshire coast, together with 

 a small barrel of salt water. They were placed in an aquarium, from which 

 the dust was excluded as carefully as possible ; a "high-water mark " was 



