BOLEOSOMA TESSELLATED DARTERS 295 



of back and sides a very pale strawish olive, over which are distributed 

 small brownish dots and splashes and more or less vaguely W-, X-, 

 and V-shaped markings, part of the latter forming an indefinite lateral 

 row, — rather aptly called "sand-paper" darter by one of our collectors; 

 back finely tessellated with dark brown in and between 6 or 7 large, 

 but sometimes indistinct, quadrate blotches; sometimes an obscure cau- 

 dal spot; belly in life translucent pale greenish to dull golden; head 

 olivaceous above, with dark brown specks; a dark streak in front of eye, 

 a rather broad bar-like blotch behind it; lower part of cheek very pale 

 greenish; opercle olivaceous, with dark spots above; pupil dull black; 

 iris with a narrow rim of golden next to pupil; dorsals, caudal, and pec- 

 torals barred, the latter only near base; ventrals and anal plain, the anal 

 pale whitish, ventrals of a creamy to strawish hue. Spring males with 

 head, and with first dorsal, anal, and ventral fins a very dark bluish black, 

 and rest of body and fins more or less clouded with same color, the sides 

 being marked with 8 or 9 bars of darker color, the bars indistinct in some 

 specimens and in instances wholly submerged in an almost uniform 

 black coloration; in the less dusky spring males, in which barring is 

 plainest, the spinous dorsal may have dark color mostly confined to the 

 membrane between the first and second spines and to an irregular narrow 

 edging on posterior half of fin. No difference between coloration of late- 

 summer males and females. Head short, 3.5 to 4.2 in length, with 

 decurved snout, protruding eyes, and flat and sloping forehead; width 

 of head 1 . 6 to 2 . 1 in its length; interorbital space narrow and concave, 

 '6.5 to 8.5 in head; eye round, protruding above level of cranium, 3.2 

 to 3.8 in head; nose bluntly pointed, 3.3 to '4.2; mouth rather small, 

 inferior, maxillary reaching past front of orbit; cleft 2.9 to 3 . 7 in head; 

 lower jaw included; gill-membranes narrowly connected, distance from 

 muzzle to angle and to back of orbit equal. Dorsal fin VIII-X (usually 

 .IX), 10-12, the spinous and soft portions often united at base; height of 

 first dorsal 1 . 7 to 2 . 1 in head, second 1 .4 to 1.8 (height of first 70 to 

 92 per cent, of second) ; caudal truncate; anal I, 6 to 9 (usually 7 or 8) ; 

 pectorals . 9 to 1 . 2 in head ; separation of ventrals usualh r a little less 

 than their width at base. Scales 5-7 (usually 6), 45-52, 6-8 [8-11]; 

 lateral line as a rule complete, but 2 or 3 pores occasionally lacking; 

 rheeks typically* naked or with only a trace of scales on upper portion ; 

 opercles covered with small scales ; nape either scaled or naked ; breast 

 •in typical* specimens naked, fully or more or less scaled in many speci- 

 mens from the Rock, upper Illinois, and upper Wabash basins, in which 

 cheeks also are scaly; belly with ordinary scales. 



The Johnny darter, much the most abundant of its subfamily in 

 this state, and taken by us in 243 collections, is not so much a thor- 

 oughly typical as a fairly average darter — distinguished, that is, less 

 by a precise adaptation to the special darter environment than by a 

 fairly equal distribution throughout the entire class of situations fre- 

 quented by the various species of the group. 



*See table on page 297. 



