154 
bulletin of the bureau of fisheries. 
of the Etheostominae very noticeably, whereas in Lucioperca they are more nearly as in Perea. This 
character varies, however, in Lucioperca, and in L. sandra Cuvier & Valenciennes, from the Danube, 
the submarginal elements are quite short. L. volgensis Pallas, from Astrachan, has the submarginal 
elements conspicuously elongated. Boulenger unites the American Stizostedion with Lucioperca, and it 
is impossible to find any substantial difference in the scales. Curiously, the pike perch, Stizostedion 
vitreum (Mitchell) from Cedar Point, Toledo, Ohio, has the submarginal elements elongated as in L. 
volgensis; while 5 . canadense (C. H. Smith) from Big Sycamore Creek, Tenn., has them short as in L. 
sandra. 
The species of Acerina examined are A. cernua Linnaeus (Danube River and Switzerland) and A. 
schroetser Linnaeus. I can not separate them on the scales. Acerina acerina {Perea acerina Gmelin) I 
have not seen. The genus Zingel Cloquet includes Z. zingel Linnaeus, Z. asper (Linnaeus) and Z. streber 
(Siebold), unless we follow Jordan, and recognize a second genus {Aspro Cuvier & Valenciennes) for 
the second and third of these. I have Z. zingel and Z. streber. The scales of Z. streber, at least in my 
material, are smaller and shorter, otherwise there is no appreciable difference. Scales of Z. zingel (fish 
loX inches long) are about 4 mm. long and broad, therefore much larger than any of the American 
Etheostominse, the largest of which are less than 2 mm. long. In the larger American scales {Percini 
and Diplesion) the basal radii are much stronger than in Zingel, and more parallel. Jordan remarks 
that Zingel is perhaps the ancestor of the entire group of Etheostominae. 
Of Perea I have the three known species, European perch, P. fiuviatilis Linnaeus, from Sweden; 
American perch P . flavescens (Mitchell), from Lyndonville, Vt., and Falmouth, Mass.; P. sekrenkii Kessl 
from Khuldscha. P. fiuviatilis (fish 17 inches long) 
has large reddish scales, fully 10 mm. long, with six 
basal radii; basal margin deeply cut into long lobes; 
apical teeth short; subapical elements quadrate, but 
not elongated. P. fiavescens (fish 6 inches long) has 
colorless scales about 4 mm. long; six basal radii; 
lobes of basal margin not so long; apical teeth short; 
subapical elements distinctly elongated. In P. sekrenkii the scale is about the same size as that of P. 
fiavescens, but longer, and broader above the middle than at the base, the reverse being conspicuously 
true of P . fiavescens . The basal radii are three to six, and the lobes of the basal margin are shorter than 
in either of the other species. The apical marginal elements are distinctly elongated. Scales of P. 
sekrenkii are readily knorni from those of Lucioperca volgensis by their peculiar form, narrowing below 
(basad), the shorter apical teeth, and the much more strongly crenate base. 
It seems quite impossible to make a key to the genera or species of American darters, Etheostominae. 
I give a list of the species studied, with some notes. 
Percina caprodes (Rafinesque), log perch. Chili, Ind. Scales about i }4 (some ipi) mm. long, 
and about as broad; about 6 to 10 basal radii; apical teeth long. 
Hadropterus pkoxocephalus (Nelson). Durkey’s Ferry, Wabash River, Ind. 
H. macrocephalus (Cope). Obeys River, Olympus, Tenn. 
H. aspro (Cope & Jordan), black-sided darter. Upper Eel River, Allen Co., Ind. 
H. guntkeri (Eigenmann & Eigenmann). Cheyenne River, Valley City, N. Dak. 
H. peltatus (Stauffer). Neuse River, Raleigh, N. C. 
H. ouachitae (Jordan & Gilbert). Marked Tree, Ark. 
H. scierus Swain. Tippecanoe River, Marshland, Ind. 
H. roanoka (Jordan & Jenkins). Neuse River, Raleigh, N. C. “Cotype.” 
H. maxinkuckiensis Evermann. Lake Maxinkuckee, Ind. 
All have small scales with quite long apical teeth. They differ in size; thus H. macrocephalus has 
scales hardly over i mm. long, while H. peltatus has them fully 1.5 mm., the fishes in each case being 3 
inches long. H. peltatus and scierus have scales of about the same size, but the apical teeth are distinctly 
longer in scierus. 
•r::c]Qanac::=^ 
Fig. 14. — PercaJiavescensCPercidse) . Ctenoid structures. 
Bureau of Fisheries. 
