308 FISHES OF ILLINOIS 



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 show- 

 ing 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 below 

 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 hack 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 1.5 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 [9-11]; lateral line some- 

 what flexed upward anteriorly, about parallel* with line of back; 3 to 15 pores 

 usually 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 coefficient 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 other- 

 wise most frequently in rivers, large and small, and somewhat 

 less frequently in creeks. Our coefficients 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 dis- 

 tribution. It is wanting in all our collections from the up- 

 land glacial lakes. 



Its ecological separateness from its nearest allies, notwith- 

 standing its close resemblance to them, is shown by our coeffi- 

 cients of association of this species with the banded, the rainbow, 



* Least distance between lateral line and middle of back equal to l /$ depth of body. Com- 

 pare with Boleichthys fusiformis. 



