ERIMYZON — CHUB-SUCKERS 81 



portion of the cheeks below; pharyngeal bones weak, 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. 



(Map XVI) 



Mitchill, 1S15, 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 everywhere 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, covering 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 5.1 to 

 6.5, depth 4.6 to 5.6 in length of body; interorbital 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 in 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 rule 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. 



