FISHES OF PENNSYLVANTA. 101 


The brook silverside or skip jack is found in streams and ponds in the 
Ohio and Mississippi valleys. It has also been discovered recently in 
some of the southern states from South Carolina to Florida. 
This fish grows to a length of four inches and is important only as 
food for larger species. It has been kept in the aquarium but does not 
endure captivity. The brook silverside is a surface swimmer, and the 
name skip jack is derived from its habit of skipping out of and along 
the surface of the water. It abounds in “clear pools left in summer by 
the fall of the waters in the stream, which has filled them.” 
ORDER ACANTHOPTERI (THE SPINY-FINNED FISHES). 
Famity APHREDODERIDZ (Pirare Percues). 
Genus APHREDODERUS Le Svevz. 
115. Aphredoderus sayanus (GILLIAMs). 
The Pirate Perch. 
The body is moderately stout, oblong, somewhat compressed posteriorly. Scales 
etenoid. The dorsal fin is continuous, with three or four spines and eleven soft rays; 
the anterior spines much the shortest. The anal has two spines and six rays. The 
mouth is rather large for the size of the fish ; the lower jaw somewhat longer than 
the upper ; the maxilla reaches to front of eye. Jaws, vomer and palatine bones 
with villiform bands of teeth. Lateral line wanting. The depth of the body is two- 
sevenths and length of the head one-third of the total without caudal. The eye is 
two-ninths as long as the head. The origin of dorsal is much in advance of the mid- 
dle of the total length. The pectorals do not reach as far back as the ventrals ; ven- 
trals more than one-half length of head. The long anal spine three-sevenths length 
of head; the caudal is rounded. Scales in 48 to 55 series. The color is variable, 
sometimes olivaceous at other times dark brown with numerous dark punctulations; 
a dark bar at the base of the caudal followed by a light one. 
The pirate perch ranges from New York westward to Minnesota and 
in the Mississippi valley it extends to Louisiana. In Pennsylvania the 
species occurs in Lake Erie, probably in tributaries of the Ohio and in 
the lower Delaware. It grows toa length of four inches. Nothing is 
recorded about its habits except that it is very voracious and feeds at 
night. It is common in sluggish streams and ponds in the shelter of 
aquatic plants. In a pond near Patchogue, Long Island, we found the 
pirate perch to be quite common and the owners of the pond mistook 
it for the young of German carp which they had introduced. 
This is one of the most interesting little fishes of the fresh waters, 
particularly because the position of the vent varies with age. In the 
young it is behind the ventrals while in the adult it is in the throat. 
