170 ACANTHOPTEKYGII. GOBIADtE. 
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 ap- 
plicable 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 briefiy noticed. The cavities selected are 
almost always nearer the low than high water- 
mark; they have generally rather narrow open- 
ings, 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 bril- 
liant 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 iii capturing the adult animal at the 
