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U.S. NATIONAL MUSEUM BULLETIN 2 82 



Figure 2. — Size change in the number of serrations of the posterior edge of the pectoral 

 spine in Noturus stigmosus. Noturus eleutherus differs little from stigmosus in the number 

 of serrae. In most other species of the subgenus Rabida, it is not possible to distinguish 

 species on numbers of serrae as the overlap is great. There is some suggestion (in the 

 several species plotted) that females average more serrae than do males. 



tions of young, and egg counts for Noturus flavus; Fowler (1917b) and 

 Clugston and Cooper (1960) reported on Noturus insignis, and 

 Thomerson (1966) gave data on Noturus junebris. Species of Noturus 

 lay comparatively few eggs, undoubtedly the joint result of small 

 body size and large egg size. N. flavus, according to published accounts, 

 lays more than others, probably averaging between 500 and 1000. 

 The madtoms lay few eggs, many species perhaps less than 100 at 

 a time. 



Spawning occurs in middle or late summer in the north. Since the 

 species are characteristic of warm water, this is to be expected. 

 Probably the late spawning and warm water environment contribute 

 importantly to the relative geographic constancy in fin ray counts 

 of most species. The time of spawning in the south has not been 

 reported, but it probably begins in early spring and extends well 

 into the fall. Hellier (1967) reported young (size not given) of Noturus 

 gyrinus collected in the Santa Fe River, Florida, from April to Sep- 

 tember. Thomerson (1966) was unable to determine the age of a 

 sample of Noturus junebris from Florida, but based its age interpreta- 

 tion on the length frequency distribution of the sample, assuming 

 late season spawning. If the spawning season does begin earlier and 



