308 FISHES OF ILLINOIS 



its rather large and oblique mouth; depth of caudal peduncle 2 . 1 to 

 2,6 in its length. Color brownish olive, the back with S or 6 quadrate 

 saddle-like blotches of blackish to greenish brown; 8 or 9 greenish brown 

 bars on sides, becoming obscure in front of caudal peduncle; interspaces 

 between bars rust-red to orange; belly orange; head slaty olive, with 

 dark streak in front of eye and below ; cheeks olivaceous, tending to bluish 

 brown or chestnut ; opercle olivaceous with sprinklings of iridescent golden 

 green; eye dull, the pupil dull black and iris chestnut; spinous dorsal 

 tipped with a narrow edge of pale blue, under which is a narrow band- 

 like row of orange- red spots; lower half of fin chiefly pale blue; soft dorsal 

 irregularly spotted with rusty orange; pectorals transparent; ventrals 

 dusky at base; anal pale; one of the most elegantly colored of our darters. 

 Females somewhat duller in color, examples in preservative showing 

 less prominently than males the dark bar-like blotch near base of spinous 

 dorsal. Head 3.7 to 4.2, rather large, uniformly tapered above and be- 

 low to the end of the bluntly pointed muzzle; width of head 1.7 to 2.3; 

 interorbital space about half of eye, 5 .4 to 7 .4 in head; eye round, 3 .3 to 

 4; nose slightly less than eye, 3.5 to 4.3; mouth rather large, terminal, 

 oblique, upper lip above level of lower margin of orbit; maxillary past 

 front of orbit; cleft 2 . 8 to 3 . 3 in head; jaws subequal; gill-membranes 

 narrowly connected, distances from muzzle to angle and to back of orbit 

 about equal. Dorsal fin X-XI (occasionally IX), 12 or 13, the spinous and 

 soft portions scarcely separated; height of first dorsal 1 . 9 to 2 . 2 in head, 

 second 1 . S to 2 (height of first 74 to 98 per cent, of second) ; caudal 

 rounded or slightly emarginate; anal II, 7 or 8^; pectorals 1.1 to 1.3 in 

 head ; separation of ventrals scarcely more than ^ their width at base. 

 Scales 6 (occasionally 5), 49-57, 7—9 [9—1 1] ; lateral line somewhat flexed 

 upward anteriorly, about parallel* with line of back; 3 to IS pores usu- 

 ally lacking; cheeks, opercles, and nape closely scaled; breast naked; 

 belly covered with ordinary scales. 



This little species, very abundant in Illinois, and represented by 

 161 collections, differs from the remainder of its subfamily in its 

 average distribution. It is consequently among those darters least 

 frequently found in company with others, and our associative coeffi- 

 cient for the species is but 1.47, the general average for the subfamily 

 being 2 . 02. It seems to prefer the stagnant water of lowland lakes 

 and sloughs, and occurs otherwise most frequently in rivers, large 

 and small, and somewhat less frequently in creeks. Our coeffi- 

 cients for these various waters are 2 . 02 for bottom-land lakes and 

 ponds, 1.23 for the larger rivers, 1.13 for the smaller rivers, and 

 .99 for the creeks. Its preference for the larger streams and the 

 waters of their neighborhood is indeed plainly evident from the map 

 of its distribution. It is wanting in all our collections from the up- 

 land glacial lakes. 



*Least distance between lateral line and middle of back equal to J depth of body. 

 Compare with Boleichthys fusiformis. 



