we were led to speak of the nest-making instinct of a species of Stickleback, and extracted some particulars from a communication of great interest made to the Royal Institution of Cornwall. In the same paper the author gave an account of two other fish-nests, one of which was found to belong to the present species. "It may perhaps be doubted whether the term nest is strictly applicable to this, as the fish merely makes use of a natural cavity in the rock, in which the ova are deposited, and remain adherent; but as it shows a deviation from what has been considered as the usual mode of spawning in fish, it may be briefly noticed. The cavities selected are almost always nearer the low than high watermark; they have generally rather narrow openings, and the roofs are smooth, or are at least not much broken by fissures. On the roofs and sides of such cavities the ova are deposited, and thickly arranged, looking as if they were vaulted with a pavement of round stones. As the ova are of a beautiful and bright amber-colour, with a highly polished surface, they have a very brilliant appearance as the light falls upon them in their dark recess. They are semi-circular in form, and about one-tenth of an inch in diameter. Having succeeded in hatching them, I proved them to belong to the Common Shanny (Blennius pholis). This opinion of their character has been repeatedly confirmed, as it is the habit of this fish to retire beneath stones, or to crevices of the rock, during the recess of the tide, where they remain dry until the sea returns. By enlarging the openings of the cavities, I have generally succeeded in capturing the adult animal at the
