1404 Fishes. 



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 traehurus. 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 



