many of the more delicate began to grow sluggish and manifestly unhealthy; some of the fishes, some of the mollusks, particularly the univalves, and the smaller Crustacea, died off one by one; and the water began to have a tainted odour, arising, as I discovered, from the carcases of some of the animals that had died beneath the shelter of the stones.
The whole contents were therefore removed: the plants and animals, such of them, at least, as appeared in health, being temporarily placed in a pan, while the water, sand, gravel, and clay were thrown away, the interior of the Tank well cleansed, and refilled with new materials. With these I got on better; though, as it was always an object with me to have as many animals under observation as possible, I did not care to confine the number to such as would maintain the balance with the plants. I preferred to change the water periodically, as the sea flowed invitingly up to the very door, and accordingly renewed it regularly about once in three weeks. Hence this must not be considered as evidence pro or con on the philosophy of the subject, a question which Mr. Warington's experience triumphantly settles.
THE BLACK GOBY
This fish (Gobius niger), of which I had several about 3 inches long, soon became tame, feeding readily After a few weeks they would come out of their shelter as soon as a stick was put into the water, and at length grew so bold as to snap at and seize the stick. A little Two-spot Goby (G. Ruthensparri), elicited the cannibal propensities of his black cousin, for no
