270 BRITISH FRESHWATER FISHES 



From this it will be seen that all of the twenty-two 

 species are inhabitants of the continent of Europe, and 

 that whilst only one of them crosses the Pyrenees into 

 Spain, and about half of them get over the Alps into 

 Italy, quite a number extend far into Asia, and two 

 even are common to Europe and North America. 

 Moreover, it will appear that whilst all the species 

 occur in Yorkshire, and nearly all in the Trent, the 

 Ouse, and Norfolk, there are parts of these islands 

 where the true freshwater fish-fauna is a very poor 

 one. Ireland has only ten of the twenty-two species, 

 namely, Planer's Lamprey, Gudgeon, Tench, Minnow, 

 Rudd, Bream, Loach, Pike, Ten-spined Stickleback, 

 and Perch, and one of these, the Minnow, is reputed 

 to have been introduced about one hundred years ago. 

 In Britain there is a considerable diminution in the 

 number of species towards the north. Thus in Loch 

 Lomond and the Teith there are present only Planer's 

 Lamprey, Tench, Minnow, Roach, Loach, Pike, Ten- 

 spined Stickleback, and Perch. Of these the Roach 

 is absent from the Tay, Dee, and Deveron, whilst the 

 Tench occurs in these systems only in ponds where 

 it has been introduced. Finally, in the Northern 

 Highlands, as in the outlying islands, there seem to 

 be no indigenous true freshwater fishes, although the 

 Pike has been introduced into some of the lochs and 

 rivers, and the Minnow into the Spey. 



A similar decrease in the number of species takes 

 places from east to west ; the Burbot, the Barbel, and 

 the White Bream are found only in English rivers 

 which flow into the North Sea. In Dorsetshire there 

 are found only Planer's Lamprey, Gudgeon, Tench, 

 Roach, Dace, Chub, Minnow, Loach, Ten-spined 

 Stickleback, Pike, Perch, Bull-head, and perhaps 



