310 CONTRIBUTIONS TO NORTH AMERICAN ICHTHYOLOGY IV. 
cortiiinly occur, but sucli are not necessarily “hybrids.” {Salmo, tlio 
Latin name of salar, originally from salio, to leap.) 
The following observations on the species of trout are taken, with 
some slight abridgment and alteration, from Dr. Gunther’s account of 
this family (Cat. Fish. Brit. 3Ius. vi): 
TIuto is no other group of lishos which otlors so many difficulties to the ichthyol- 
ogist, with regard to the distinction of the species, as well as to certain points in 
tlieir life history, as this genus. * * * The almost inlinite variations of these lishcs 
are dependent on age, sex, and sexual development, food, and the properties of the 
water. * * * The coloration i.s, lirst of all, subject to variation, and consequently 
this character hut rarely assists in distinguishing a species, there being notone which 
would show ill all stages the same kind of coloration. The young in all the species 
of this genus are 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 Sahno alone, but also to 
Thymulhis and probably to Corcgonun. The number of bars is not quite constant, but 
the migratory trout have two (or even three) more than the river-trout. When the 
SdlmoiicH 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 inlluence on the coloration of the outer jiarts than on that of the ilesh ; 
thus, the more variegated specimens are frequently out of condition, whilst well-fed 
individuals, with pinkish Ilesh, are of more uniform though Itright colors. » • * 
The water has a marked inlluence on the colors. Trout with intense ocellated spots 
are generally found in clear, rapid rivers and in alpine pools ; in the large lakes, with 
l)ebbly bottom, the fish are bright silvery, and the ocellated spots are mixed with or 
replaced by X-shai)ed black spots; in dark holes, or lakes with i)eaty bottom, they 
often assume an almost uniform blackish coloration. 
The brackish or salt water has the etfect of giving them a bright-silvery coat, 
without or with few spots, none of them ocellated. With regard to size, the various 
species do not i)rescnt an equal amount of variation. Size appears to depend on the 
abundance of the food and the extent of the water. Thus, the migratory species 
do not appear to vary considerably in size, because they find the same conditions in 
all the localities inhabited by them. A widely-spread species, however, like Sahno 
fario (or in America, Sahno purjynrahis), when it inhabits a small mountain pool, with 
scanty food, never attains a weight of 8 ounces, while in a largo lake or river, where 
it finds an abundance of food, it attains to a weight of 14 or IG po.;nuls. Such large 
river-trout are fre(pieutly named or described as Salmon-trout, Bull-trout, Steel-heads, 
etc. 
The proportions of the various parts of the body to one another vary exceedingly, 
in the same species, with age, sex, and condition. 
The fins vary to a certain degree. The variation in the number of rays in any ono 
genus (except Oncorhijnchus) is inconsiderable, and of no value for specific distinction. 
Although some species appear to bo distingnislu'd by a comparatively low dorsal and 
anal tin, yet the proportion of the height of these fins to their length is a rather un- 
certain character. In most of the species the fin-rays are longer during the stages of 
growth or development. The caudal fin especially undergoes changes with age. 
Young specimens of all species have this fin more or less deeply excised, .so that the 
young of a species which has the caudal emargiuato throughout life is distin- 
guished by a deeper incision of the fin from the young of a species which has it 
truncate in the young state. The individuals of the same species do not all attain 
to maturity at the same size. 
