2l8 



A HISTORY OF FISHES 



pools ; in the large lakes with pebbly bottom the fish are bright 

 silvery, and the ocellated spots are mixed with or replaced 

 by X-shaped black spots ; in pools or parts of lakes with muddy 

 or peaty bottom the Trout are of a darker colour generally, 

 and when enclosed in caves or holes they may assume an 

 almost uniform blackish coloration." In some Irish lakes the 

 Trout on the boggy side have been observed to be dark and 



Fig. 88. 

 Slender File-fish {Monacanthus scriptus) among Eel-grass. (After Beebe.) 



comparatively shapeless, whereas, on the gravelly side they 

 are of the beautiful and sprightly form generally to be found 

 in rapid gravelly or sandy streams. Two or three Trout from 

 the Thames sent to the British Museum during recent years 

 exhibited all the characteristic silvery and black-spotted appear- 

 ance of typical Sea Trout, but proved to be merely Brown 

 Trout that had been living in shallow reaches with light 

 gravelly bottom. In a stream near Ivy Bridge the Trout were 

 observed to have become much lighter in colour after the water 



