124 VERTEBRATE ANIMALS OF THE UNITED STATES 



S. c. horeuni (Girard). Head slender: upper Missouri. 



3. Percina Haldeman. Body slender, elongate, slightly com- 

 pressed; midventral line with enlarged plates, which may fall off leaving 

 a naked strip; caudal margin concave; mouth overhung by snout; 

 teeth on vomer and palatines; lateral line continuous; air bladder and 

 pseudobranchiaj rudimentary: 2 species. 



P. caprodes (Rafinesque) . Log-perch. Length 200 mm.; head 4 to 

 4.7; depth 5 to 6.5; color yellowish green, with about 15 black transverse 

 bars extending from the back to the belly and alternating with shorter 

 ones; a round spot at the base of the tail fin; rays of dorsal fin XIII to 

 XVII-12 to 17; anal II, 9 to 12; scales 9-90 to 95-15: Great Lakes region 

 to North Carolina, Mississippi and the Rio Grande; in Atlantic coastal 

 streams sothward to North Carolina; in large, clear streams; generally 

 common. 



P. rex Jordan & Evermann. Length 150 mm.; head 4; depth 4.6; 

 scales 11-83 to 85-19; anterior dorsal fin with a broad orange band 

 towards the margin: Roanoke River; rare. 



4. Hadropterus Agassiz. Black-sided darters. Body very small, 

 elongate, cylindrical, brightly colored, with a series of large dark more 

 or less confluent blotches along the lateral line and rounded blotches on 

 the back; mouth terminal; teeth on jaws and vomer and usually the 

 palatines; midventral area with enlarged scales which in most species 

 may be shed, leaving the belly naked; fins large; ventral fins well 

 separated: about 12 species. 



Key to the Species of Hadropterus 



ai Median line of belly naked as far as the anus, 

 bi Species west of the Alleghenies. 

 Ci Ventral fins widely separated. 



di Color blotches more or less transverse H. evermanni. 



d2 Color blotches more or less longitudinal. 



Ci Lower jaw as long as the upper //. phoxoccphalus. 



62 Lower jaw shorter than the upper. 



fi Scales very small, about 90 in the lateral line.H. macrocephalus. 

 (-2 Scales 50 to 70 in the lateral line. 



gi Cheeks scaly; scales 60 to 70 H. aspro. 



g2 Cheeks usually naked; scales 50 to 60. . .H. ouachilce. 



C2 Ventral fins not widely separated; cheeks naked H. evides. 



1)2 Species east of the Alleghenies. 



Ci Scales 52 to 56 H. peltatus. 



C2 Scales 48 //. roanoka. 



ao Median line of belly scaly at least posteriorly. 



bi In the Mississippi Valley H. scierus. 



hi In the southern and Gulf States H. nigrofaciatus. 



