126 FISHES OF PENNSYLVANIA. 

D. X, 12; A. II,7. Fiverows of scales above the lateral line, eight below, and forty- 
five between the head and tail. Nape and breast generally scaleless. 
The body of the male is olivaceous with darker blotches on the back. Twelve bars 
of indigo blue running obliquely downward and backward across the sides. The 
spaces between the bars are orange as are the throat, breast and cheeks. The base of 
the spinous dorsal is crimson, surmounted by orange and margined with blue. The 
soft dorsal is orange, the base and margin blue. In the female the blue and orange 
colors are chiefly wanting and the dorsal, anal and caudal are checked or barred. 
The blue darter, blue Johnny, rainbow darter and soldier fish, is found 
in the Ohio valley and in some parts of the Mississippi valley. In 
Pennsylvania it is limited to the western portion of the state, in the Chio 
and its tributaries. It reaches a length of two to three inches and is 
one of the most brilliantly colored of all the darters. It frequents 
gravelly bottoms in deeper parts of streams and is not common in small 
brooks. The blue darter is not so active as some of the other members 
of its family, but in coloration it is the most beautiful of all the darters. 
Genus PERCA (Arrepi) Linn. 
145. Perca flavescens (Mircuttt). 
The Yellow Perch. (igure 12.) 
The yellow perch has a fusiform and moderately elongate body, its greatest height 
at the ventral origin two-sevenths of the total length without the caudal and nearly 
equal to the length of the head. The least depth of the caudal peduncle equals one- 
third length of head. The greatest width of the body equals one-half its greatest 
height. The head is moderately large, its length contained three and one-fourth 
times in the standard, with pointed snout, one and one-third times as long as the eye. 
The interorbital region is flat, its width one and one-half times the diameter of the 
eye. The mouth is rather large, the jaws equal, and the maxilla reaching to below 
middle of pupil. The preopercle is coarsely dentate on its hind margin, the teeth 
on the superior border directed partly upward and partly backward, those on the 
lower limb pointing downward and some of them forward. The scapulaand humerus 
are finely serrate. Scales on the cheeksin about thirteen rows from before back ward. 
A single row or two imperfect rows of scales on the subopercle. Four short rows ot 
scales on the upper anterior part of the opercle. Gill-rakers six -+ fourteen, the 
longest one-half as long as the eye. The spinous dorsal begins over the base of the 
pectoral ; the first spine is one-third as long as the head to the end of the opercular 
spine; the fourth and longest spine is as long as the eye and snout combined ; the 
last spine is minute and concealed in the dorsal furrow. The soft dorsal in the 
specimen described is preceded by two spines, the first two-thirds as long as the eye 
and one-half as long as the second. The longest ray is as long as the longest spine, 
and twice as long as the last ray. The ventral origin is under the fourth spine of the 
dorsal; the fin equals one-fifth of the total length without the caudal. The anal 
origin is under the fourth or fifth soft dorsal ray. The first anal spine is one-third 
as long as the head and nearly as long as the second. The last anal ray is less than 
one-half as long as the longest, which is one-half as long as the head. The caudal is 
notched, the middle rays contained one and one-third times in the length of the 
outer rays. The pectoral is as long as the ventral. D. XV, II, 18; A. II, 8; V.I, 4; 
P. 15; scales 7-57-13. The lateral line curves upward in a long curve following the 
dorsal outline until below the end of the soft dorsal where it becomes straight and 
median. Color olivaceous varying into greenish or bluish, the sides yellow with 
about six to eight dark bands, the widest wider than the eyeislong. The upper 
fins are olivaceous, the lower orange and rosy. The specimen described, No. 22,862, 
United States National Museum, from Washington, D. C., is nine inches long. 
