148. No indication of lateral line 149. 

 Lateral line present, although sometimes broken 150. 



149. Body compressed, about three times as long as deep; with 38 or less 



evenly arranged scales along the side; west to Texas 



Erimyzon sucetta (Lacepede) Chub Sucker, Creek Fish 

 Body longer, less compressed; with 39 or more irregularly arranged 



scales along the side; eastern and central states (Considered by some 



to be a subspecies of the preceding) 



Erimyzon ohlongus (Mitchill) Chub Sucker, Mullet 



150. Lateral line broken; Great Lakes area to Montana 



Minytrema vielanops (Raf.) Spotted Sucker 

 Lateral line complete 151. 



151. Upper lip not protractile; lower lip in two separate lobes; formerly most 



of central U. S., possibly extinct 



Lagochila lacera J. 6? B. Rabbit-mouth or Harelip Sucker 

 Upper lip protractile; lower lip entire or more or less lobed 152. 



152. Head transversely concave between the eyes; eye very far back in head; 



lower lip tuberculate, very thick, with two almost separate lobes; snout 

 much produced downwards; eastern and north'central states 

 Hypentdium nigricans (LeSueur) Hog Sucker 

 Head flat above or slightly convex; eye somewhat nearer middle of head 



153. 



153. Eye somewhat behind middle of head; no posterior fontanelle, the parie- 



tal bones being united in this region (on top of skull) ; restricted region 

 of Virginia and W. Virginia in mountain headwaters 

 Thoburnia rhothoeca (Thoburn) 

 Eye about midway in head; with a large posterior fontanelle 154. 



154. Mouth large, oblique; with six to ten large cylindrical teeth on the 



lower part of the pharyngeal bar; Michigan to Georgia and Arkansas 

 Placopharynx carinatus Cope Big-jaw Sucker 

 Mouth smaller, horizontal; pharyngeal teeth all small 155. 



155. Dorsal rays 12 to 15; under fins often red; getting to be over a foot 



long in most species; usually found in rivers and ponds (A difficult 

 group. Revised by Hubbs, 1930, Univ. of Michigan Museum of Zool. 

 Misc. Pub. No. 20. A representative species is given here.) ; eastern 

 and central U. S. 



Moxostoma aureolum (LeSueur) Common Redhorse 

 Dorsal rays 10 to 12; under lins not much reddish; small suckers usually 

 found in mountain streams; south Atlantic states 156. 



156. Scales pale spotted in lengthwise rows 



Scartomyzon cervinus (Cope) Jumping Mullet, Crawl-a-bottom 

 Back dusky 



Scartomyzon rupiscartes (J. & J.) Jumprocks 



157. With a barbel present on the maxillary (minute and usually concealed 



by the fold near the corner of the mouth) 158. 



No trace of maxillary barbel 182. 



276 



