BOLEOSOMA — TESSELLATED DARTERS 395 



paper" darter by one of our collectors; hack finely tessellated with dark 

 brown in and between 6 or 7 large, but sometimes indistinct, quadrate 

 blotches; sometimes an ol)scure caudal 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 pectorals 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 be- 

 tween the first ancl second spines and to an irregular narrow edging on pos- 

 terior 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, pro- 

 truding 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.S 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 con- 

 nected, 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 usually 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; cheeks typically* 

 naked pr 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 mam^ specimens 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 sub- 

 family in this state, and taken by us in 243 collections, is not so 

 much a thoroughly typical as a fairly average darter — distin- 

 guished, that is, less b}^ a precise adaptation to the special 

 darter environment than b}^ a fairl}^ equal distribution through- 

 out the entire class of situations frequented b}^ the various 

 species of the group. 



It occurs virtually' everj^where in the state except in the 

 larger streams and in lowland lakes and sloughs, where it is 

 strikingly rare. It has occurred but twice, for example, in over 

 five hundred collections made by us from the Illinois River at 



* See table on page 297. 



