pared for a vigorous defence. The spines are covered with a skin or sheath, which the creature has a power, of drawing from the points and leaving them bare. This fish will live a long time out of water, pro- vided it be kept slightly wet, but soon dies on immersion in fresh water. Those fish that swim deeply, are able to retain life much lon- ger than those that swim near the surface ; and the former are more sluggish in their movements, and require less aerated water for respi- ration. The more active are surface-swimmers. The immersion in fresh water acts like a poison, death not resulting from any variation in the respirable quality of the water. If a sea-scorpion, after being taken from the sea, be constantly kept wet with salt-water, it will live for a considerable time, the gill-covers acting as if surrounded by wa- ter. If the gills be kept wet and the skin dry, the creature gets rest- less, croaks, the gills move more rapidly than before, and it then dies at an earlier period than when kept altogether moist. If the gills be wetted with fresh water well aerated, life is not so long retained, but the fish seems more active for a time, and dies at last in almost a state of plethora.
Rough-tailed Stickleback, Gasterosteus trachurus. Rare in con- sequence of their being no favourable localities for them, for they breed so rapidly that they soon overstock a pond. I am informed that they build nests of dried leaves and grass.
Fifteen-spined Stickleback, Gasterosteus spinachia. This is a pretty and remarkable species : it is common on all our shores in sheltered bays ; in spring and summer it ventures into the open sea : it is very active and pugnacious, using the dorsal spines with effect on small fish with which it may engage. In the pools between tide- marks it may be seen either remaining balanced in the water under the shelter of some hanging sea-weed, prowling among the sand and rocks for the minute crustaceans on which it feeds, or carefully guard- ing its neatly stitched nest, hanging among the neighbouring rock. Its mouth is small, and snout long, from which it is enabled to take its prey from beneath stones, or in the crevices of the rocks, whether they be horizontal or perpendicular. It never takes a bait, and is very timid, unless when watching its young, when it becomes sometimes bold and fearless : it spawns about April and May. The description of the nest and eggs of this fish having already appeared in the pages of the 'Zoologist' (Zool. 795), it is unnecessary to repeat it. The nests are not uncommon, for one evening while wandering over the rocks of Mount's Bay with a friend, for the purpose of showing him one, we
