FAMILY PER CIDAE 205 



6. Premaxillaries distinctly protractile, even the midline separated by a deep 



groove from the snout 7 



Premaxillaries scarcely protractile, bound down to the snout by a fleshy 

 frenum. which, especially in Imostoma, may be crossed by a shallow gi'oove 

 when the mouth is tightly closed 9 



7. Lateral line lacking on posterior part of body; dorsal fins widely separated; 



snout very blunt and rounded 



Bluntnose Darter, Boleosoma chlorosomuvi (Hay) 



Lateral line nearly or quite complete; dorsal fins little separated: snout 

 more or less sharp (Boleosoma nigrum). 8 



8. Nape, cheeks, and breast well scaled 



Scaly Johnny Darter, Boleosoma nigrum eulepis Hubbs and Greene 



Nape, cheeks, and breast scaleless 



Central Johnny Darter, Boleosoma nigrum nigrum (Rafinesque) 



9. Midline of belly with a definite single file of scales more or less enlarged, 

 thickened, deciduous, and separated by a slight groove from the scales on 

 either side; these scales may be only weakly specialized in Imostoma and 

 sometimes little modified in females of other genera; one such scale between 

 pelvic fins: pelvics separated by a space at least three-fourths as wide as 

 base of either fin; anal fin usually almost as large as the second dorsal, some- 

 times even larger; body typically elongate and little compressed 10 



Midline of belly without a median file of specialized scales; no specialized 

 extra-spiny scale between pelvic fins: pelvics separated by a space less than 

 three-fourths as wide as base of either fin: anal fin smaller in area than 

 second dorsal fin; body typically deeper and more compressed. 14 



10. Snout extended forward as a small conical protuberance beyond the upper 

 lip: mouth horizontal: anal spines very flexible; scales 78-103 in lateral line; 



crossbars numerous and narrow 



Northern Logperch, Percina caprodes semifasciata (De Kay) 



Snout not extended beyond upper lip; mouth more or less oblique; anal 

 spines stiff; scales fewer than 80; crossbars either broad or obsolete 11 



11. Belly largely scaleless medially, but crossed before anus by a bridge of scales; 

 scales of midline only incipiently modified; premaxillary frenum usually 



hidden by a shallow furrow behind upper lip 



River Darter, Imostoma shumardi (Girard) 



Belly mostly scaled and with the scales of the midline strongly modified, at 

 least in males; premaxillary frenum usually not hidden by cross furrow. .12 



12. Gill-membranes united into a broad curve distinctly more distant from tip 

 of snout than is the back of the eye; lateral blotches small; spinous dorsal 



with a submarginal orange band in life 



Slenderhead Darter, Hadropterus phoxocephalus (Nelson) 



Gill-membranes not united, but meeting at a sharp angle and on the midline 

 scarcely farther from tip of snout than is the back of the eye; lateral bars or 

 blotches large; spinous dorsal without orange strijje 13 



13. Scales in lateral line 52-67; cheeks naked; bands broad, large, and squarish; 

 color gilt in life. . . .Gilt Darter, Hadropterus elides (Jordan and Copeland) 

 Scales in lateral line 65-85; cheeks at least partly scaled; bands narrower; 

 not gilt in life Blackside Darter, Hadropterus macidatus (Girard) 



14. Lateral line obsolete; dorsal spines usually 6; lower fins much produced and 



pointed in breeding males; adults seldom as long as 1 1/2 inches 



Northern Least Darter, Microperca microperca microperca 



