324 Bulletin ^7, United States National Museum. 



Head flattish above, the snout broad, somewhat projecting over the large, 

 oblique mouth ; maxillary reaching front of eye. Barbel evident. Eye 

 large, as long as snout, \\ in interorbital space. Scales small, crowded 

 forwards, those on the back smaller. Dorsal beginning over last ray of 

 ventrals. Height of dorsal fin 1 to \\ in head ; free margin of the fin con- 

 cave, the anterior rays produced and extending beyond the others when 

 the fin is depressed ; longest anal ray 1^ to If in head, its form similar to 

 that of dorsal. Dusky above ; sides somewhat silvery ; an obscure dusky 

 band through eye around snout ; fins plain. Length 6 inches. Streams 

 and lakes, from Lake Superior east to the Adirondack region and New 

 Brunswick ; not very common, except northward, (plumbeus, lead-colored. ) 



Gobio plwiibeus, AGASSIZ, Lake Superior, 366, 1856, Lake Superior. (Coll. Agassiz.) 

 Ceralichtliys prosthemius, COPE, Cypr. Perm., 365, 1866, Montreal River, Keweenaw Point, 



Lake Superior. (Coll. Dr. J. H. Slack.) 

 Nocomis milneri, JORDAN, Bull. U. S. Nat. Mus., x, 64, 1877, Lake Superior. (Type, No. 20332. 



Coll. Milner.) 



Ceratichthys plumbeus, GUNTHER, Cat., vn, 176, 1868. 

 Couesius dissintilis, JORDAN & GILBERT, Synopsis, 218, 1883, in part. 

 Couesius prosthemius, JORDAN & GILBERT, Synopsis, 219, 1883. 



539. COUESIUS DISSIMILIS (Girard). 



Head 4 to 41 ; depth 4 to 5; eye 4 to 5 in head ; snout 3 to 4. D. 8 ; A. 

 8 ; scales 12-68-8, varying from 64 to 72. Very close to C. plumbeus, the 

 only important difference being in the form of the dorsal fin. Height of 

 dorsal fin li to li in head ; free margin of fin nearly straight, the anterior 

 rays little if at all produced ; when depressed barely reaching end of 

 other rays ; longest anal ray If in head, the free margin of fin straight, 

 the first rays where depressed not reaching beyond others. Upper Mis- 

 souri and Black Hills region ; generally common ; probably a variety of 

 C. plumbeus. (dissimilis, dissimilar, to Semotilus atromaculatus.) 



Leucosomus dissimilis, GIRARD, Proc. Ac. Nat. Sci. Phila., 1856, 189, Milk River and Little 

 Muddy River, Montana. (Type, No. 158. Coll. Suckley.) 



540. COUESIUS GREENI, Jordan. 



Head 4 T L -; depth 4-jV; snout 3f. D. 8; A. 8; scales 10-57-7; teeth 2, 

 4-4, 2. Body robust, the back convex before the dorsal, profile of 

 head straight and rather steep, space between eyes broad and flattish, 

 3 in head. Snout bluntish, but rather long; premaxillary just above 

 level of lower part of pupil ; maxillary reaching almost to orbit, 3f in 

 head ; barbel well developed, not quite at end of maxillary ; its length 

 considerably less than that of pupil. Mouth moderately oblique, the 

 lower jaw slightly included. Dorsal fin inserted behind base of ventrals 

 and behind middle of body, at a point midway between preopercle and 

 base of caudal, the fin of moderate height. Pectoral shortish, 1| in 

 head, ventrals nearly 2. Caudal well forked, the lobes equal; scales 

 larger than in most related species, scarcely reduced forward and but 

 lit tie .smaller on the back than on the sides ; 36 scales in front of the 

 dorsal. Color dark olive above, the sides reddish silvery ; slight traces 

 of a lateral band, a dark streak below the eye, undulating and extending 



