'4 U. S. BUREAU OF FISHERIES. 



color is light olivaceous, with eight or nine dusky orange vertical 

 bars extending from the dorsal to the ventral line. The barring 

 becomes evident when the fish is 1.4 cm, long. The mottled and 

 spotted effect appears when the fish measures about 4 cm. All the 

 fins of the immature fish are of a green cast, at first sight colorless 

 and transparent. The opercle is a brighter metallic green with one 

 of the vertical orange bands extending across it. The eye of the 

 immature fish is large. 



BREEDING SEASON. 



The breeding season of Lepomu hmnUis is an extended one, begin- 

 ning early in spring and not ending until at least the first week in 

 August for Iowa fish and lasting for Louisiana fish until the first 

 week in September. The mating season begins in Louisiana ordi- 

 narily about the first week in April. In Iowa it begins at least six 

 weeks later, occurring usually about May 20. Well-developed fry 

 of at least 2 weeks of age have been taken as early as April 25 in 

 Louisiana. Exceptionally cold weather may delay the first spawn- 

 ing several days, particularly since there appears to be a critical tem- 

 jDerature at which egg laying occurs. This has not been accurately 

 studied by observation, but by water temperature (Table 1) and 

 breeding records for both Iowa and Louisiana it may be concluded 

 fairly to be approximately 65° F. (Fig. 1). It is of interest to note 

 that the pigmy sunfish Elassoma zon^tuni^ of much smaller size and 

 an inhabitant of a distinctly different environmental association, 

 breeds at least a week earlier than humiUs (Barney and Anson, 1920), 

 The critical breeding temperature, however, for the two species is 

 about the same, tlie earlier Elassoma mating occurring in shallower 

 and clearer water, these conditions allowing for an earlier warming 

 of the water. 



Tari,e 1. — Average mean temperature of water at Mound, La., and Fairport, 



Iowa. 



It is not to be understood that the breeding season for a single fish, 

 either male or female, may last through the entire spring and summer. 

 The period of egg laying for an individual fish probably does not 

 extend through more than a few hours of a single day. The ex- 

 tension of the laying season is caused by the attainment of sexual 

 maturity by the younger fish that have not spawned previously dur- 

 ing the spring or summer. The later limit of the breeding season of 

 Lepomis hu77ulis is based on records of two small females taken at 

 Mound — one carrying 50 and the other 80 ripe or nearly mature 

 ova — on August 29. Many males taken on the same day were flow- 

 ing with milt. The latest record of a gravid female at Fairport is in 

 a collection of August 3. This fish carried 175 eggs that appeared to 

 be mature. A number of males taken in the same collection were 

 ripe. 



