BRITISH FEESH-WATER FISHES. 



INTRODUCTION. 



The British Fresh-water Fishes are exhibited in the British Saloon 

 at the far end of the Bird Gallery. On entering the Saloon from 

 the Bird Gallery the visitor turns sharply to the right and finds 

 the fishes facing him, occupying two adjacent wall-cases. In the 

 limited space available it has been impossible to adhere strictly lo 

 a systematic arrangement, but the general plan is that the Sturgeon 

 and the Salmonoids occupy the case on the right and the 

 Cyprinoids that on the left ; the other families, which together 

 include but a small proportion of the species, are placed above, 

 below and to the left of the Cyprinoids. Each specimen exhibited 

 is provided with a number, and these numbers are repeated in 

 the Guide. 



Many of our fresh-water fishes spend part of their life in the 

 sea ; some of these, such as the Stickleback, both feed and breed 

 in either fresh or salt water ; others, like the Salmon, feed in the 

 sea and breed in the rivers, whilst the Eel, on the contrary, 

 descends to the sea to breed. Marine fishes that ascend rivers 

 may form perumnent fresh-water colonies, and in time these may 

 become distinct races or even species. All the fresh-water fishes 

 peculiar to the British Isles, such as the Char and Whitefish of 

 different lakes, and the Killarney Shad, are closely related to 

 marine fishes that spawn in fresh water. On the otlier hand, our 

 Perch, Pike, Roach, Bream, etc.. are true fresh-water fishes ; 

 they and their relatives are found only in fresh water. All our 

 fishes of this type are found also on the continent of Europe, and 

 as they cannot cross the sea it is evident that they reached our 

 islands at a time when the latter were joined to the continent and 

 our eastern rivers were, in all probability, tributaries of the Rhine. 



The accompanying figures of the Perch and Trout (fig. 1) are 

 intended to iUustrate some of the differences used in characterising 

 the families. In the Trout the maxillary bones form part of the 

 upper border of the mouth, but in the Perch the praemaxillaries 

 exclude them from the oral margin. In the Trout the pelvic fins 

 are abdominal, far behind the pectorals ; in the Perch they are 



