186 CONTRIBUTIONS TO NORTH AMERICAN ICHTHYOLOGY IV. 



ttt Species of small size, witL tlie scales not mncli deeper than long, less closely 

 imbricated; body obloug or elongate, little elevated ; mouth 

 moderate, oblique or horizontal ; dorsal fin inserted close be- 

 hind ventrals; nuptial colors mostly brilliant (Alburnops 

 Grd.). 

 roseus, rubricroceus, lutipinnis, chlorocephalus, chiliticus, chahjhceus, 

 chrosomus, xwmocephalus, phimbeoltis, lacertosus, shiimardi, hlenniua. 

 tt Teeth without evident grinding surface. 



a. Teeth with the edges serrate; scales closely imbricated cercostigma. 



aa. Teeth not serrate; scales loosely imbricated, scarcely higher than loug. 

 J). Dorsal fin inserted directly over the ventrals; anal rays 7-9; eye very 

 large; scales large (^'Episema" Cope & Jordan). 



ariommus, sccibriceps, jejunus, Icuciodue. 

 hh. Dorsal inserted behind ventrals altipinms, amdbilis, megalops. 



* * Scales small, about 55 in the lateral line bivittatus, tinnyanogensis. 



$§ Anal fin more or less elongate, its rays 10-14. 



c. Scales comparatively small, more or less closely imbricated, and with 

 the exposed edges deep, as in Codoma and Lnxilus ; scales iu 

 front of dorsal small ; teeth with grinding surface more or 

 less developed. (Lythrurus Jordan.) 

 d. A black spot at base of dorsal in front. 



ci/anocejyhaltis, alripes, diplcemiiis, ardens, pimctiilatus. 



dd. A black spot at the upper anterior part of dorsal ruhripinnis. 



ddd. No distinct black spot on the dorsal. 



e. Body short and deex> bellus. 



ee. Body slender and elongate 7nafufirius, lirus. 



cc. Scales comparatively large, not higher than loug, and not closely im- 

 bricated ; scales in front of dorsal large ; teeth without grind- 

 ing surface. (Minnilus.) 



/. Anal fin long, with about 14 rays oligaspis. 



ff. Anal fin moderate, its rays 10 or 11. 



g. Scales above lateral line in about 9 series u^nbratilis. 



gg. Scales above lateral line in 5-7 series. 



h. Ventral fins reaching beyond middle of dorsal. 



ecepticus, photogenis, ielescopus, stilbius, percobromiis, ru~ 

 bellus, dineinus, rubrifrons, jcmezanns. 

 hh. Ventral fins scarcely reaching beyond front of dorsal. 



micropta'yx. 

 ^ Anal fin short, its rays 7-9 (rarely 10). 



* Scales large, 35-50 in the lateral line. 



t Teeth with the grinding surface more or less developed. 



t Species attaining a large size, with the scales along the flanks nearly 

 twice as deep as long, and so closely imbricated that the exposed sur- 

 faces are very narrow ; back elevated and convex in the adult male ; 

 the lower jaw included; dorsal fin inserted directly opposite ventrals. 

 {Ltixihis Eaf.*) 

 260. M. coriSBltOBS (Mitchill) J. & G.— Shi tier ; Bed-fin; Dace. 



Body elongate in the .yonug, iu the adult short, compressed, with 

 the anterior dorsal region much swollen and gibbous. Head rather 

 heavy, compressed, rounded between the ejes, the snout bluntish. 

 Mouth moderate, nearly horizontal, the jaws nearly equal, the lower 

 somewhat included. Eye moderate, 4-5 in head, maxillary scarcely 



* Rafinesque, Ichth. Oh. 1820, 47 : type Luxilus chriisocephalus\iiii.=^ C yprinuii curnutaa 

 Mitch. (From Latin Z«x, light = " Shiner ". ) {^^ Hypa'depis 'Biiivdi.) 



