STICKLEBACKS. 505 



Of "Sticklebacks" (Gastrosteus) about ten species are 

 satisfactorily known, one of wMch (G. spinacUa) lives in salt 

 and brackish water, whilst the others inhabit principally 

 fresh waters, although they all are able to exist in the sea. 

 They are confined to the Temperate and Arctic zones of the 

 northern hemisphere. The British freshwater species are 

 the Three-spined Stickleback {G. aculeatus), which sometimes, 

 especially in Central Europe, lacks scutes, sometimes has a 

 series of scutes along the side of the body ; the Four-spined 

 Stickleback {G. spimdosus) and the Mne-spined Stickleback 

 {G. pungitius). The commonest N"orth American species is 

 G. novebomcensis. The habits of all the freshwater species 



Fig. 230. — Gastrosteus novelDoracensis. 



are very similar. The common European species {G. aculeatus) 

 is an active and greedy little fish, extremely destructive to the 

 fry of other species, and consequently injurious in ponds 

 where these are sought to be preserved. It is scarcely to be 

 conceived what damage these little fishes do, and how greatly 

 detrimental they are to the increase of all the fishes in general 

 among which they live ; for it is with the utmost industry, 

 sagacity, and greediness that they seek out and destroy all 

 the young fry that come their way. A small Stickleback, 

 kept in an aquarium, devoured, in five hours' time, seventy- 

 four young dace, which were about a quarter of an inch long, 

 and of the thickness of a horse hair. Two days after it swal- 

 lowed sixty-two ; and would, probaby, have eaten as many 

 every day could they have been procured. The Stickleback 



