80 THE FRESH-WATER FISHES OF EUROPE. 



is scarcely visible. The dorsal spine, like that of the ventral fin, is always 

 shorter than in the Common Stickleback, but always broader at the base, 

 and is more strongly notched on both sides. The base of the soft-rayed 

 dorsal fin is longer, and extends just before the vent. The anal fin begins 

 farther back, and its rays are somewhat shorter. The caudal fin is about 

 one-half the length of the head ; the three-cornered plate between the ventral 

 fins is smaller and more pointed in males than in the females, in which it is 

 considerably broader than in G. aculeatus. There are four lateral shields. 

 They touch the base of the shield below the spinous ray, and reach down 

 to the pelvic girdle. This variety is found at Gorz, in Istria, and the Lake 

 of Garda, and other localities in Lombardy, where it is known as Spinarola. 



A four-spined Stickleback has been named Gasterosteus spinulosus by 

 Jenyns and Yarrell. It is recorded from near Edinburgh, Arran,.and Berwick. 

 A five-spined Stickleback, taken near Warrington, has been recorded by Mr. 

 J. Peers. These can only be regarded as another series of variations of 

 Gasterosteus aculeatus. 



Gasterosteus pungitius (LINN^US). The Ten-spined 



Stickleback. 



D. 911/11, P. 910, V. 1/1, A. 1/911, C. 5/12/6. 



The body in this fish is compressed, elongated, with the sides naked, 

 except for about a dozen keeled scales, which terminate the lateral line on 

 the tail, though they are not present in all varieties. The lateral line is 

 indicated only by a furrow. The operculum is rather larger than in G. 

 aculeatns. There are from nine to eleven, more frequently ten, low, free, 

 dorsal spines, which are similar and nearly equal in size, each with a slight 

 fin-membrane. They are erectile at the will of the fish. There is no 

 interval between the last dorsal spine and the dorsal fin. The anal fin, 

 which has a recurved spine in front, is opposite to the dorsal. The ventral 

 fin consists of one spine and one soft ray. The spine is attached to a 

 triangular pelvic shield, which is keeled, and has something of the form of a 

 sternum. The fins are transparent. 



The colour is more uniform than in the Common Stickleback. The 

 upper side of the body is green or bluish -black, with darker transverse bands. 

 The belly and sides are silvery, but with change of season become silver- 

 blue, orange, or reddish. The male in summer is often black on the under 

 side in Germany, and in Britain its wedding dress is an intense velvety black, 

 without the slightest trace of red. The black colour develops first on the 



