78 FISHES OF PENNSYLVANIA. 

Commission averaging about one inch per month up to the age of one 
year. 
Size.—The average individuals of this species are less than one foot 
in length, but specimens measuring nearly two feet and weighing eight 
pounds have been recorded. The Neosho station has individuals nearly 
one foot long at the age of one year. 
Habits and Reproduction.—The rainbow feeds on worms, insect larvze 
and salmon eggs. In streams in which’ the California salmon and rain- 
bow exist together, the rainbow is the one species most destructive to 
salmon eggs. Spawning takes place in winter and early spring, varying 
with temperature and locality. The bulk of the eggs are usually taken 
in January, February and March, and the average yield from each female 
is about 900 eggs. 
Uses.—The rainbow is a good table fish although held in variable 
estimation in different localities. In most places, however, it is con- 
sidered fully equal to the common brook trout. On the McCloud river, 
Cal., it is regarded as superior to salmon. 
92. Salmo fario Linyzvs. 
The Brown Trout. (Figure 6.) 
The brown trout of Europe was introduced into the United States from Germany 
in February, 1883, and in subsequent years. It has now become thoroughly accli- 
mated in the fresh waters of many of the states. 
The body of this trout is comparatively short and stout, its greatest depth being 
contained about four times in the length without the caudal. The caudal peduncle 
is Short and deep, its depth equaling two-fifths the length of the head. The length 
of the head in adults is one-fourth of the total length without caudal, or slightly less. 
The diameter of the eye is about one-fifth of the length of the head and less than 
length of snout. The dorsal fin is placed nearer to the tip of the snout than to the 
root of the tail; the longest ray of this fin equals the distance from the eye to the 
end of the opercle. The ventral is under the posterior part of the dorsal ; its length 
is about one-half that of the head. The adipose dorsal is placed over the end of 
the anal base ; it is long and expanded at the end. The caudal is emarginate in 
young examples, but nearly truncate in specimens ten inches long. The pectoral is 
nearly one-sixth of the length without the caudal. In the male the jaws are pro- 
duced and very old ones have a hook. The maxilla extends to the hind margin of 
the eye. The triangular head of the yomer hasa transverse series of teeth, and the 
shaft of the bone bears two opposite or alternating series of strong, persistent teeth. 
D. 13-14; A. 10-11; P. 138; V. 9; scales 25-120-30; pyloric coeca 38-51; vertebree 57-58. 
On the head, body and dorsal fin usually numerous red and black spots, the latter 
circular or X-shaped and some of them with a pale border. A yellowish margin, 
usually present on the front of the dorsal and anal and the outer part of the ventral. 
The dark spots are few in number below the lateral line. The ground color of the 
body is brownish or brownish black, varying with food and locality. 
Names.—In European countries in which this species is native it bears 
the name of trout or brook trout, or the equivalents of these terms. In 
Germany it is Bachforelle ; in Italy, Trota ; in France, la Truite. In 
the United States it is known as the brown trout and von Behr trout, 
the latter in honor of Herr von Behr, late president of the Deutscher 
