RIVER SILVERSIDE. 919 
very elongate, translucent; dorsal spines four; scales smal]. This genus contains but 
a single species, peculiar to the fresh waters of the Western States—a small fish, very 
slender and graceful, and of delicate organism. 
* 
111. LaBpimpEsTHES sIccuLus Cope. 
River Silverside; Skipjack. 
£ 
Chirostoma sicculum, Corr, Proc. Acad. Nat. Sci. Phila., 1865, 81. 
Labidesthes sicculus, Copz, Proc. Amer. Phil. Soc., 1870, 455.—JoRDAN, Man. Vert., 1st 
Kd., 1877, 2d Ed., 1878, 261. 
Description.—Form very slender, the depth contained 6 to 7 times in length; the head 
about 44; eye large and round contained 34 times in the length of the side of the head, 
and 14 times in the length of the snout; top of head and muzzle plane, the latter con- 
vex transversely, its tip about even with that of the lower jaw; front with a median 
ridge; teeth slender and simple; scales small; in 14 longitudinal and 75 transverse 
series; anal fin very long, nearly one-third the length of the body; first dorsal short, 
with 4 very weak spines; D.1; V.10; A. I, 22; Ventrals I, 5; color very clear, trans- 
lucent olive; in life quite transparent; above dusted with black points; sides with a 
very distinct, silvery band, which covers one row and two half rows of scales, edged 
above with plambeous; cheeks silvery. Length 3 to 4 inches. © 
Habitat, Michigan to Tennessee, west to lowa, Detroit River (Cope), Sandusky Bay, 
Clinch River (Cope), Cumberland River, Illinois River, Wisconsin River, and in most 
streams of Ohio and Indiana. 
Diagnosis.—This is the only fish found in Ohio with a long, slender 
body, two dorsal fins, and a bright, silvery stripe along the sides. 
‘Habits —This little creature is one of the most singular and elegant 
of our fishes. It occurs in great abundance where found, and is espec- 
ially numerous in clear pools left in summer by the fall of the waters in 
the stream which has filled them. It swims near the surface, and often 
throws itself out of the water, for which reason it is known to Indiana 
boys by the name of “Skipjack.” It is an attractive creature in the 
aquarium, but from its delicacy of organization hard to keep alive. 
FAMILY XIX. APHREDODERIDA. THE PIRATE 
PERCHES. 
Body oblong, moderately compressed, covered with ctenoid scales; dorsal fia single, 
high, with but three or four spines, which are rapidly graduated, the first being quite 
short; ventral fins thoracic, without distinct spine, and with seven soft rays; mouth 
moderate, the lower jaw slightly proj2cting, the maxillary reaching to the anterior 
border of the eye; teeth in villiform bands, on jaws, vomer and palatines; pharyngeals 
- narrow, the lower separate, with villiform teeth; preorbital, preopercle and other bones 
of the head strongly serrated; branchiostegals six; gill membranes free from the 
isthmus; air-bladder simple; pyloric cwca about twelve; scales moderate, ctenoid; no 
