Nearly six months ago the caretaker placed in this river twenty young carp from Bathurst. Some of them were enticed from their cavernous resting-places by the bright rays of the lamp, and appeared to be tolerably vivacious and in fair condition. They seem to have all they require except the solar rays; but what is life without sunshine! They ought to be scientifically observed, for there is a theory that in three generations of darkness they will become blind. This has been the fate of the fishes in the Mammoth Cave of Kentucky, and it is stated that their blindness is the result of a law of Nature, which does not continue to supply organs or powers which have ceased to be necessary. Dr. Forwood, in his history of the Mammoth Cave, says:--"The fishes are of a peculiar species, and are of a class known as viviparous, which give birth to their young alive, and do not deposit eggs after the manner of most other fishes. They have rudiments of eyes, but no optic nerve, and are, therefore, incapable of being affected by any degree of light.... It has been proved that these eyeless fishes prey upon each other. In shape they somewhat resemble the common catfish, and rarely exceed eight inches in length." Professor Silliman published the following in his "Journal" for May 1851:--"Of the fish there are two species, one of which has been described by Dr. Wyman in the _American Journal of Science_, and which is entirely eyeless. The second species of the fish is not colourless like the first, and it has external eyes, which, however, are found to be quite blind. The crawfish, or small crustacea, inhabiting the rivers with fish are also eyeless and uncoloured; but the larger-eyed and coloured crawfish, which are abundant within the caves, are also common at some seasons in the subterranean rivers, and so also, it is said, the fish of the Green River are to be found in times of flood in the rivers of the Caves." Dr. Forwood gives also the following quotations, on the authority of Professor Agassiz, an eminent naturalist in the department of ichthyology:-- "The blind fish of the Mammoth Cave was for the first time described in 1842 in the 'Zoology of New York,' by Dr. Dekay, part 3rd, page 187, under the name of 'Amblyopsis spelæus,' and referred, with doubt, to the family of 'Siluridæ,' on account of a remote resemblance to my genus Cetopsis. Dr. J. Wyman has published a more minute description of it, with very interesting anatomical details, in vol. xlv. of the 'American Journal of Science and Arts,' 1843, page 94.