158. Tail fin slightly emarginate; a moderately large European species intrc 



duced into the eastern states 

 Tinea tinea Linn. Tench 

 Tail fin distinctly emarginate or forked 159. 



159. Upper lobe of tail fin longer than the lower lobe, in adult specimens; 



about twelve inches long; California 



Pogonichthys macrole pi dolus (Ayres) Splittail 

 Lobes of tail fin equal 160. 



160 With two barbels on each side of the mouth; two inches long; Arkansas 

 and Kansas 



Extrarius tetranemus (Gilbert) 

 With one barbel on each side of the mouth 161. 



161. Premaxillaries not protractile 162. 

 Premaxillaries protractile 164. 



162. Scale count about 50; lips thick; eastern states 



Parexoglossum laurae Hubbs Eastern Tonguetied Minnow 

 Scale count 60 to 70; lips thin 163. 



163. Snout projecting considerably beyond the mouth; color dark; widely dis' 



tributed over northern U. S., south to North Carolina 



Rhimchthys cataractae (C. 6? V.) Long-nosed Dace 

 Snout projecting very little beyond the mouth; with a dark band along 

 each side; Maine to Minn, and southwards 



Rhinichthys atronasus (Mitchill) Black-nosed Dace 

 B.himchthys atratulus (Hermann) 

 (Includes R. meleagns Agassiz) 



164. Barbel situated before the end of the maxillary 165. 

 Barbel situated at the end of the maxillary, at the junction of the upper 



and lower lip 167. 



165. Dorsal fin with a distinct black blotch at the base, from the first to the 



third ray; Maine to N. J. and Wyoming 



Semotilus atromaculatiis (Mitchill) Horned Dace 

 No such fin spot 166. 



166. Scale count about 45 ; east of the AUeghenies 



Leucosomus corporalis (Mitchill) Fallfish 

 Scale count 50 to 75; with scattered dark-colored scales forming a spotted 

 pattern above; Lake Erie and southwards 



Margariscus margarita (Cope) Pearl Minnow 



167. Scales small, 58 to 90 in the lateral line 168. 

 Scales larger, 35 to 56 in the lateral line 176. 



168. Pharyngeal teeth thick, blunt, scarcely hooked, 5-5 in the main row; 



scale count about 75; with two dark bands along each side; about a 

 foot long; northwestern U. S. 



Mylocheilus lateralis A. ^ P. Columbia River Chub 



Mylocheilus caurinus (Richardson) 

 Pharyngeal teeth slender, hooked, 4-4 in the main row; smaller fishes 169. 



169. Barbels well developed; pharyngeal teeth 2-4-4-2; lateral line complete; 



northern states 



277 



