Longest ray of dorsal fin about half as long as the base of the fin; often 

 larger 129. 



128. Mouth mostly before a vertical from the nostrils; Mississippi Valley to 



the Rio Grande 



Carpiodesvelifer (Raf.) Quillback 

 Carpiodes cyprinus (LeSueur) 

 Mouth farther back, the nostrils being very near the end of the snout; 

 Ohio Valley and westward 



Carpiodes dijformis Cope Blunt'nosed River Carp 

 Carpiodes velifer (Raf.) 



129. Mouth mostly before a vertical from the nostrils; Nebraska area 



Carpiodes thompsoni Agassiz Lake Carp 

 Carpiodes forhesi Hubbs 

 Mouth farther back, the nostrils being very near the end of the snout; 

 Ohio Valley to Texas 



Carpiodes carpw (Raf.) Common River Carp 



130. Scales small, with the scale count more than fifty-five 131. 

 Scales larger, with the scale count less than fifty-five 148. 



131. With a large hump back of the head; Colorado River basin 



Xyrauchen texanus (Abbott) Humpback Sucker 

 (Xyrauchen cypho (Lockington) ) 

 Not so ' ^ 132. 



132. Upper lip thin; mouth terminal; western states 133. 

 Upper lip thick; mouth inferior 138. 



133. Scale count about 65; Utah and Nevada 134. 

 Scale count 70 to 80; vicinity of Klamath Lakes, Oregon 136. 



134. Lips with numerous tubercles; Utah Lake 



Chasmistes fecundus (C. 5? Y.) Webug Sucker 

 Lips not tuberculate 135. 



135. End of nose high; Utah Lake 



Chasmistes liorus Jordan June Sucker 

 Nose less prominent; Pyramid Lake, Nevada 



Chasmistes cujus Cope Couia, Kweewee, Quiwee 



136. Snout short and even 



Chasmistes hrevirostris Cope Yen, Tswam 

 Spines of premaxillaries projecting to form a knob on top of snout 137. 



137. Dark spotted above 



Deltistes luxatus (Cope) Lost River Sucker 

 Chasmistes luxatus Cope 

 Dusky above 



Chasmistes stomias Gilbert Klamath Lake Sucker 



138. Head depressed, transversely concave between the eyes; eye well behind 



middle of head; scales even; scale count 45 to 55; eastern and north' 

 central states 



HypenteUum nigricans (LeSueur) Hog Sucker 

 Head less depressed; position of eye various; scale count often greater; 

 scales smaller and crowded anteriorly 139. 



274 



