6 SALMONID^E OF BRITAIN. 



The fact must not be lost siglit of that, if salmon ever depended for their 

 entire subsistence in the fresh water they ascend, the amount of food they would 

 require would be so great in a river as to constitute a nuisance, and cause pollution 

 were it left unconsumed. 



The number of circal appendages present in each form of Salmonoid has been 

 considered a criterion by which the various species may bo differentiated ; but, on 

 a mure careful investigation, they have proved to be inconstant iu their numbers. 

 Still, the broad fact that all the species possess many of these appendages is 

 important; for, if we examine the true fresh- water fishes, as the carps, we find 

 them destitute of these appendages, while those fresh-water forms which possess 

 them in any number, as perch and rnfFe in the Percida) and burbot in the Gadida>, 

 appear invariably to have marine relatives ; consequently, their presence in 

 the salmon family tends towards a supposition as to their also having a marine 

 ancestry. 



It may reasonably be asked on what gi-ounds it can be held that a species of 

 fish as the brook trout, S. fario, in which vomerine teeth are normally present 

 throughout its life,* could be a retrograde descendant from a salmon S. salar, in 

 which these teeth are shed as the adult stage is obtained ? If we look at the very 

 young salmon, as when in its par stage, we find the same distribution'of colours as 

 are present in many adult front or the immature livery of the salmon continued 

 throughout the life of the more minute S. fario. While in America the land- 

 locked salmon, S. salar, which occurs in some lakes, and only attains a few 

 pounds in weight, would seem to be somewhat ari-ested in its development, and 

 par bands are visible even in adults on the scales being rulabed oif. In the 

 larger lake Wenern variety of the land-locked salmon, although the par bands do 

 not continue through life, the fish is extensively spotted. 



It must be admitted that these finger mai'ks are usually lost in adult trout, 

 but when they pass their existence in small streams these immature marks may be 

 continued through life, in fact the trout has not arrived at the silvery stage of the 

 smolt. And what we find in colour we similarly perceive in dentition : the double 

 row of vomerine teeth, so indicative of the fresh- water trout, are invariably seen 

 in the immature par, or to put it in another way, a sign of immaturity in the 

 trout is a persistence of the infantile dentition of the salmon. Consequently, it is 

 to be expected that if this permanence of vomerine teeth is symjitomatic of a 

 change from a marine to a fresh-water state of existence we should expect to find 

 such occurring in anadromous sea trout, whether iS'. trulta or iS'. cambricus, did they 

 commence residing in rivers and lakes. And this is exactly the difference which we 

 perceive does occur, the vomerine teeth in such forms becoming more persistent 

 through life than if the fish had retained its anadromous propensities. 



Salmon on enteiing rivers, as a general rule, deteriorate in quality, similarly 

 to what has been shown takes place in sea fishes, prevented migrating to the ocean, 

 unless under peculiarly favourable conditions ; therefore it becomes a question 

 of what is the effect on salmon debarred from going to the sea ? Here 

 doubtless the reply of all observers is to one effect — that they sensibly dwindle ia 

 size, and generally the breed dies out, for even the land-locked salmon is a 

 dwarfed race— in fact, similar in its character to the dwarfed breed of herrings 

 imprisoned in the brackish Baltic sea. 



the scales lose their brilliant silvery lustre, and the flesh becomes soft and pale. Dr. Giinther 

 (Ciitnl. vi, IBfie, p. 3) placed the fish of the genus Salmo as "inhabitants of the fresh waters 

 of the Arctic and temperate parts of the Northern hemisphere, many species descending to the 

 sea after having deposited their spawn." In 1800 he stated of the char " none of which 

 migrate to the sea as far as our present knowledge goes" (Cntid. vi,| p. 145), while in the 

 Zoological liecord for 1804, of the char he remarked " the origin of which cannot be deduced from 

 a marine species." Frank Buckland, on the contrary, observed, " I consider the salmon a sea fish 

 proper ; nevertheless, this sea fish ascends the rivers and streams in order to deposit its eggs, for, 

 unlike other sea fish, it does not breed in the sea " (Familiar Hist. Ilrit. Fish. p. 321). 



* Char do not possess teeth on the body of the vomer, and possibly those systematists are 

 correct who place them in a distinct genus from the salmon and trout. But this work not being 

 intended to refer to any extent to such disputed points, I have considered it unnecessary to enlarge 

 on this (luestion and followed those authors who have suppressed the separate genus Salvelini. 



