NATURAL HISTORY OF AMIA CALVA LINNiEUS. 61 



and not be able to return to his swarm. In that case the swarm perishes unless, 

 as sometimes happens, it unites with the swarm of some other male and thus gains 

 protection. 



From all this it results that observation, as continuous as it can be made, 

 yields only fragmentary individual histories, so that the account which follows 

 must be regarded as the average made by piecing together many such fragments. 

 Even thus numerous details still remain to be worked out. 



II. OBSERVATIONS. 



i. Secondary Sexual Characters — The descriptions of the adult fish given by 

 systematists, e.g. Jordan and Evermann ('96, p. 113), are sufficient for ordinary 

 purposes, but in work on the habits it is necessary to distinguish the sexes, often at 

 a distance of ten or twenty feet, so that some further account of the secondary 

 sexual characters is desirable. 



The males on the average are smaller than the females and are further distin- 

 guished from them during the breeding season by their color (see plate in Dean, '98). 

 In the breeding male (PI. VII, Fig. 4) all the fins, dorsal, caudal, pectoral, and pelvic, 

 are of a bright green, like that of the aquatic plants; the tail-spot, which in the 

 female is small, indistinct, not bordered, and usually stated to be lacking, is large, 

 velvety-black, and bordered by a broad band of orange or yellow, so that as a whole 

 it is very conspicuous. The ventral surface of the male is of a lighter green than 

 the fins, and this green tinges the bronze-green of the sides up to the lateral line and 

 shows everywhere, but especially on the sides, a sheen of orange. The cheeks of the 

 male show the stripes more distinctly than those of the female, and the bronze of 

 his back and sides is both brighter and lighter, and its reticular markings of darker 

 bronze are much more distinct than those of the female. 



In the female the colors are duller and darker and the bronze tends to reddish. 

 The fins are never green, but of a brownish-red color. In the discussion of a paper 

 by the writer at the meeting of the Naturalists of the Central States at Chicago in 

 1899, Professor C. A. Kof oid stated that in the Illinois River near Havana the females 

 of Anna have green fins. Since then many specimens from the Huron River at Ann 

 Arbor have been examined and none have been found with green fins, but all with 

 fins of reddish-brown. A record of twenty-one females taken in a fyke net on the 

 spawning ground between April 18 and April 28, 1899, shows all with reddish-brown 

 fins. The spawning season of 1899 ended on April 30. By means of the green 



