ERIMYZON CHUB-SUCKERS 81 



the teeth small and slender, rapidly diminishing in length upward; 

 vertebrae 34; ribs 13; dorsal rays 11 or 12; scales large; lateral line 

 wanting at all ages; air-bladder with two chambers. Fresh waters of 

 the United States ; one species, widely distributed. 



ERIMYZON SUCETTA OBLONGUS (Mitchill) 

 (chub-sucker; sweet sucker) 



Mitchill, 1815, T. Lit. & Phil. Soc. N. Y., 1 (Cyprinus oblongus). 

 G., VII, 21 (Moxostoma oblongum); J. & G., 133; M. V., 46; J. & E., I, 186; N., 48 

 (Erimyzon oblongus); J., 64; F., 80; F. F., II. 7, 447; L., 12. 



Body oblong, compressed, the depth increasing with age; predorsal 

 region often more or less elevated and profile angled at nape in old 

 specimens; depth 3.1 to 3.9 in length. Size small, length about 10 

 inches. Coloration varying considerably with age; in adults a nearly 

 uniform brownish olive, intermixed with pinkish anteriorly, and every- 

 where with more or less of a coppery luster; paler below; fins dusky, 

 ventrals and anal most so. In young specimens the sides are marked 

 by four distinct bands of color: a dark band extending from occiput 

 backward on each side of dorsal fin to middle of caudal peduncle, cover- 

 ing 4 upper rows of scales; below this a band of light color, extending 

 from just above upper corner of gill-cleft to upper part of base of caudal; 

 next, and most prominent, a narrow band of purplish black, extending 

 from center of base 'of caudal forward along sides and through eye to 

 end of snout; and beneath this dark lateral band the sides pale to the 

 whitish or silvery belly. Adults are found which retain to a greater 

 or less extent the markings of the young, specimens from 6 to 8 inches 

 in length sometimes showing more or less plainly the dark lateral stripe, 

 as well as the apportionment of color in bands above and below; the 

 black lateral band may break up into indistinct bars with age, various 

 stages between the barred condition and a uniform dusky coloration 

 being found. Head short, compressed, considerably tapered, its length 

 3.5 to 4.1, width S.l to 6.5, depth 4.6 to 5.6 in length of body; inter- 

 orbital space weakly convex, 2.2 to 2.6 in head; snout (usually) 2.5 to 

 3.2 in head; mouth subterminal, rather small, mandibles more or less 

 obliquely set, tip of upper lip in old specimens sometimes not far below 

 level of lower rim of orbit; lower lip strongly plicate, its halves meeting 

 m a rather acute angle; eye large, 3.8 to 5.8 in head. Dorsal fin a little 

 higher than long, its developed rays 9 to 12. Scales large, 36 to 45 in 

 longitudinal series, transverse rows 13 to 15 ; scales more or less crowded 

 anteriorly and somewhat irregularly arranged on posterior half of body ; 

 lateral line as a r/ule entirely wanting at all ages; specimens occasionally 

 found with one or two imperfectly developed pores. 



Head of spring males with three large tubercles on, each side of 

 snout, two in longitudinal series in front of eye, one lower down, near 

 corner of mouth. 



