18 



possess the two sides counterparts of each other, supposing it to 

 be vertically divided exactly in the middle. 



Those who have heon deceived by its changes, into the belief 

 that the parr was not the young salmon ; and who have thought, 

 that from the many variations observable in trout, that there was 

 a multiplication of species, might find some striking analogical 

 reasons for a contrary opinion, in the natural history of the 

 flounder. In this curious fish, one side is usually colored ; the 

 other, white. But we often find them colored on both sides — 

 white on both sides — with brown patches on the white — and even 

 with their eyes and color, on the opposite side to which they are 

 generally placed. These, are far greater, and more important 

 deviations, than we find in either salmon or trout ; yet they are 

 mere varieties of one species. 



Of eels (mursena), we have three species in this county — the 

 broad-nosed, the sharp-nosed, and the snig. Strictly speaking, 

 they are fresh-water fishes ; yet, whenever they have the oppor- 

 tunity, it is said they migrate to the sea. It has been suspected, 

 however, (and as far as my own observations extend, I think 

 with truth) that a large majority of them, if not the whole, 

 remain during winter, in the estuaries. Of all our fishes, it is the 

 most susceptible of cold ; and as I remarked when speaking of 

 salmon, the mixture of salt and fresh water, is warmer than 

 either, unmixed. When, therefore, they reach the higher tem- 

 perature, it is unlikely they should pass through it, into a colder; 

 particularly, as every-day experience shows us, that the sea is 

 neither necessary to their health nor propagation. It has been 

 said, too, that those eels which have the means of migrating, 

 reascend the rivers, to deposit their spawn. It is probable, some 

 may do so : but that groat numbers of them spawn in the estuaries, 

 or in the sea, if they penetrate as far, is certain. If not, whence 

 comes those multitudes of young eels, whose periodical passage 

 up the Thames, is called eelfare? Whence the transit of those 

 myriads of elvers, up the Severn and its tributaries ? Obviously 

 the result of fish which have spawned below. Both these names, 

 eelfare and elver, appear to have the same derivation; being 



