ORANGE-SPOTTED SUNFISH, LEPOMIS HUMILIS. 3 



coming from upland glacial lakes. Tile white crappie {Pomoxis an- 

 nularis) and the green sunfish {Leporms cyanellus) are most frequent 

 associates of this fish in Illinois waters. " If one may judge from 

 its feeding structures, it is protected from serious competition with 

 these companion species by differences in its food." 



SEXES. 



The sexes of Lepomis humilis are easily distinguishable immedi- 

 ately prior to and during the breeding season. The male with flow- 

 ing milt is very brilliantly colored. The body color is opalescent 

 green, shading into a greenish blue toward the doreal fin. This 

 bluish green background is scattered w^th eight indefinite bands of 

 brilliant orange spots, extending from the dorsal fin ventrad to the 

 region halfway between the lateral line and the belly. In some males 

 there is an appearance of mottling with orange. The opalescent 

 green is particularly brilliant between the eye and the maxillary 

 and just posterior to the opercular spot, which is black, outlined with 

 a narrow border of grayish white. The opercle is crossed hori- 

 zontally by four bright golden bars. The top of the head is dark 

 metallic green. There is a small black spot above the eye. The 

 maxillary and mandible are dusky blue. The walls of the belly of 

 the ripe male are light orange, blending ventrad into white. The 

 dorsal fin is transparent, outlined with orange-red. The anal fin 

 is similar but is brighter, and its anterior and ventral edges are lined 

 Avith black. The ventral fins are salmon pink, with their lateral 

 edges dusky. The pectoral fins are very light orange and trans- 

 parent. The caudal fin is* transparent, mottled with two rows of 

 orange spots. 



The ripe female with abdominal walls heavily swollen with mature 

 eggs is not nearly as brilliantly colored as her mate. The body color 

 is olivaceous green ; the spots are not distinctly orange, being rather 

 more dusky. The color effect is one rather of mottling than of 

 banding; the mottled effect is noticeably prominent on the opercle. 

 The opalescent green color characteristic of the breeding male is 

 found in the female only between the eye and the mandible and on 

 the opercle. The black spot over the eye of the male is not promi- 

 nent in the female. The ojDercular spot is dusky in the female and 

 the border of white not nearly so contrasted as in the male. The 

 pectoral, anal, and ventral fins of tlie female are transparent and 

 colorless. The caudal and dorsal fins are mottled faintly with 

 dusky, the latter having a perceptible row of dusky spots or a duskj^ 

 band. The anal fin is more noticeable ventrad and cephalad because 

 of a dark outline. 



When preserved in formalin, it is not difficult to identify the sexes, 

 through the difference in reaction of the orange and dusky spots of 

 male and female fishes, respectivel3^ The spots on the male become 

 very pale; those of the female, brownish black. Moreover, the dif- 

 ference in "appearance in outline as well as in color" (Forbes and 

 Richardson. 1908) makes it possible to determine the sexes, "the 

 males having the forehead concave, the profile steeper, and the 

 ventrals longer." 



The immature fish of either sex of this species is of marked dif- 

 ference in color and in color i^attern from its parents. Its body 



