STIZOSTEDION AMERICAN PIKE-PERCHES 271 



compressed, subcylindrical or fusiform; depth in length as a rule 6 or 

 more; spring- males ordinarily without red or other gaudy coloration. 



e. Cranium broad between the eyes, the interorbital space 4 to 4.7 in head; 



snout pig-like; darters of large size, reaching a length of 6 inches. .Percina. 

 ee. Interorbital space narrower, 5.5 to 9 in head; small fishes, ordinarily not 

 over 4 inches in length. 



f. Body moderately slender, the depth as a rule about 6 in length (sometimes 7); 



scales not often over 70; body not hyaline in life Hadropterus. 



ff. Body extremely slender, depth 7.8 to 9 in length; scales 89-100; body hya- 

 line in life; back crossed by 4 broad, obliquely-forward-directed dark 

 bands Crystallaria. 



dd. 'Cranium more or less compressed and elevated back of eyes, n-shaped, its 



elevation as a rule noticeably more than % (to less than %) its breadth, 



(the exceptions being species with spinous dorsal less than 60 per cent. 



height of soft dorsal, and with a distinct black humeral process or scale) ; 



fishes with usually more or less compressed and comparatively shortened 



bodies, the depth in length as a rule less than 6 (4% to 6); spring males 



(except in species with low spinous dorsal) usually with brilliant red, 



blue, or green coloration. 



g. Lateral line present. 



h. Lateral line not noticeably flexed upward anteriorly Etheostoma. 



hh. Lateral line conspicuously flexed upward anteriorly, its direction parallel 

 with line of back (least distance between lateral line and middle of back in 

 B. fusiformis about % depth of body at same point) Boleichthys. 



gg. Lateral line absent; fins very short, dorsal spines 6; size very small, length 

 not over 1% inches Microperca. 



cc. Premaxillaries protractile, i. e., a groove separating them from the skin of 

 the forehead (this groove sometimes crossed by a very narrow frenum in 

 Cottogaster shumardi, in which also there is a black blotch at front and 

 back of base of spinous dorsal). 



i. Groove bet-ween skin of forehead and premaxillaries ordinarily, though not 

 always (in Illinois species), crossed by a narrow frenum; a black spot at 



front and back of base of spinous dorsal Cottogaster. 



ii. Premaxillaries freely protractile, a frenum never present; no black blotch 



at back of spinous dorsal fin. 



j. Groove separating premaxillaries from forehead inferior, not visible except 

 from below; maxillary adnate to the preorbital for most of its length, 

 nearly immovable; anal spines 2 Diplesion. 



jj. Groove separating premaxillaries from forehead superior, easily visible from 

 in front and above; maxillary separated by a groove from preorbital for 

 its entire length; anal spine single. 



k. Anal fin much smaller than soft dorsal; body moderately slender, depth not 

 over 7 in length; not hyaline in life Boleosoma. 



kk. Anal fin almost as large as soft dorsal; body extremely slender, depth in 

 length 8 to 10; body hyaline in life Ammocrypta. 



GENUS STIZOSTEDION EAFINESQUE 



AMERICAN PIKE-PERCHES 



Body elongate, fusiform, back broad; mouth large and premaxillary 

 protractile; preopercle serrated, the serrse below turned forward (antrorse) 

 and spaced rather wide apart; opercle with 1 or more spines; teeth in villiform 

 bands, in addition to which sharp canines are present on jaws and palatines; 

 pseudobranchise well developed; pyloric caeca 3; dorsal spines 12 to 15; anal 

 spines 2, slender and closely appressed to the soft rays; scales small, ctenoid. 



