310 coNTinnrTiONS TO NORTH AMERICAN ICHTHYOLOGY iv. 



certainly occur, but such are not necessarily "hybrids." (Salmo, the 

 Latin name of *v. .whir, originally from salio, to leap.) 



The following 1 observations on the species of trout are taken, with 

 some slight abridgment and alteration, from Dr. Guuther's account of 

 this family (Cat. Fish. Brit. Mus. vi): 



Then- is no other group of fishes which offers so many dilliculties to the ichthyol- 

 ;, with it-nurd to the ili.it iuct ion of tin- species, as well as to certain points in 



their life history, as this genus. * * * The almost infinite variations of these fishes 



an dependent on age, sex, ami sexual development, food, and the properties of the, 

 water. * * * The coloration is, firat of all, subject to variation, and consequently 



this character but rarely assists in dist inguishing a species, tliere being not one which 

 would show in all .ilages the same kind of coloration. The yonirj, in all the species 

 of this genus arc barred, and this is so constantly the case that it may be. used as a, 

 generic or even as a family character, not being peculiar to Salmo alone, but also to 

 J'lii/ntallttn and probably to Coreyonus. The number of bars is not quite constant, but 

 tin- migratory trout have two (or even three) more than the river-trout. When the 

 SnliitmifK have passed this " parr" state, the coloration becomes much diversified. The 

 males, especially during and immediately after the spawning time, are more in- 

 tensely colored and variegated than the females, specimens not mature retaining a 

 brighter silvery color, and being more similar to the female fish. Food appears to 

 have less influence on the coloration of the outer parts than 0:1 that of the Me.ih : 

 thus, the more \ariegaled spei imeiis are frequently out of condition, whilst well-fed 

 indi\ iditals, with pinkish flesh, are of more uniform though bright colors. 

 The water has a marked influence on the colors. Trout with intense ocellated spots 

 are generally found in clear, rapid rivers and in alpine, pools; in the large' lakes, with 

 pebbly bottom, the fish are bright silvery, and the oecllated spots aiv mixed with or 

 replaced by X- s l |a l"'d black spots; in dark holes, or lakes with peaty bottom, they 

 often asinine an almo.it uniform blackish coloration. 



The brackish or saltwater has the effect of giving them a bright-silvery coat, 

 without or with few spots, none of them ocellated. With regard to si/e, the various 

 hpecies do not present an equal amount of variation. Size appears to depend on tho 

 abundance of the food and the extent of the water. Thus, the migratory species 

 do not appear to vary considerably in si/e, because they find the same conditions in 

 all the localities inhabited by them. A widely-spread species, however, like Snlmo 

 /;-io(or in America, Sulmo jiurpiirndin), when it inhabits a small mountain pool, with 

 scanty food, never attains a weight of - ounces, while in a large lake or river, where 

 it finds an abundance of food, it attains to a weight of 1 I or 1(1 pivinds. Such 1 ; 

 ri\ er-t rout are frequently nann-d or described as Salmon-trout, I lull- trout, Steel-heads, 



etc. 



The proportions of the various parts of the body to one another vary exceedingly, 

 in the- >-ame species, with a^e. sex, and condition. 



The lins \ ary 1o a certain de- ice. The \ a rial ion in the number of rays in any ono 

 genus (except OIK -orli ijnclm:- ) is inconsiderable, and of no value for specific distinction. 

 Although some species appear to be distinguished by a comparatively low dorsal and 

 anal tin, yet the proportion of the height of the-e lins to iheir length is a rather un- 

 certain character. In most of the species the lin-ravs are longer during the stages of 

 vth or development. Tin- caudal I'm especially undergoes changes with a^e. 

 ipceimen^ "f all species have this tin more or less deeply excised, so that the 



of a species which h:n tin- caudal einargiuate throughout life is distin- 

 d by a deeper ineiiion of the I'm from the young of a species which has it 

 truncate in the yum;,' slate. The individuals of the same species do not all attain 

 to maturity at the same si/e. 



