100 FISHES OF PENNSYLVANIA. 

ORDER PERCESOCES. 
Famity ATHERINIDAS (Tue Sriversipgs). 
GENUS MENIDIA BonaPARTE. 
113. Menidia beryllina Cope. 
The River Silverside. 
The body is shorter than usual among the silversides. The spinous dorsal is well 
separated from the soft dorsal and its posterior margin extends almost to the verti- 
cal from the first anal ray. The ventral reaches to below the first ray of the dorsal. 
The length of the head is contained four and one-fourth times in the total length 
without caudal. The eye large, orbit one-third as long as the head. Mouth small. 
The mandible slightly longer than the maxilla and slightly curved. Greatest depth 
of body one-sixth of total length without caudal. Scales in lateral line thirty- 
six, transverse series ten. The lateral line is represented by a pore on the anterior 
part of the exposed portion of each scale, except on the caudal peduncle where it 
runs through a groove. 
Davalos At Lawl S i) Sven. pys kzeel os 
The caudal is deeply forked. Pale olivaceous in color with a silvery lateral band, 
on two and one-half rows of scales, with a lead colored margin. The anal base is 
lead colored ; sides of the head silvery. 
This species corresponds in many particulars with Menidia peninsule, 
of Goode and Bean, but in that species the silvery streak covers only 
one and one-half rows of scales. Thesoft dorsal in 1. peninsule appears 
to show considerable variation in the number of rays. 
The river silverside has been found only in the Potomac river so far 
as present information goes. It is believed to occur in the Susquehanna 
and probably will be found in that river. Itis distinguished among the 
Menidias by its long soft dorsal fin, which contains eleven rays besides 
arudiment. The silvery band along the sides also is very wide, cover- 
ing two and one-half rows of scales. The species has no importance 
except as food for larger fishes. 
Genus LABIDESTHES Corr. 
114. Labidesthes sicculus Cope. 
The Brook Silverside, 
The body is slender and elongate, its depth one-sixth or one-seyenth of the total 
without caudal. Length of head about two-ninths of total. Eye two-sevenths length 
of head, two-thirds length of snout. 
D. IV, I, 11; A. I, 23; scales 14,75. Caudal deeply forked. 
Color olivaceous, the fish in life translucent. The upper parts with small black 
dots. The silvery lateral band edged above with lead color and covering one row 
and two half rows of scales. Cheeks silvery. 
The genus Labidesthes has a very oblique mouth, with the upper jaw flat above 
and coneave beneath, the intermaxillaries forming a roof-like beak. The mandible 
1S CONVeXx. 
