SPAWNING BEHAVIOR IN FUNDULUS HETEROCLITUS. 34! 



2 inches. Cape Cod to the Rio Grande, in brackish waters, entering 

 streams, very abundant southward, the males more highly colored south- 

 ward, but the southern form (called gib&osus) not otherwise different." 



These sexual differences, especially those of general bodily 

 form, comparative size and shape of fins, color pattern, etc., are 

 well brought out in the illustrations (Text Plate II., Figs. 3 and 4). 

 Characters involving color, iridescence and the like cannot be 

 represented in monocrome, so it will be necessary to fall back 

 upon verbal description. For this purpose I cannot do better 

 than to refer to Jordan and Evermann's full account for details 

 not brought out in the illustrations. This account was evi- 

 dently written with reference to the fish when in "spawning 

 plumage," no reference being made to the fact that, in the males 

 especially, the color and iridescence are merely temporary adorn- 

 ments, characteristic of the breeding season alone. Before and 

 after the breeding season the males are about the same color as 

 the females perhaps a trifle greener. 



The points of sexual dimorphism to be especially born in mind 

 are the following : 



1. The male is usually somewhat larger than the female 

 the opposite being the case in the species of Fiinduhis described. 



2. The male, in "spawning plumage," is very much more bril- 

 liantly colored than the female. 



3. The body of the male is decidedly deeper but more com- 

 pressed than that of the female, differing from Finuiuliis in this 

 respect. 



4. The dorsal, anal and ventral fins are larger in the male than 

 the female, even more markedly than in Fnndnh/s. 



5. The cross-barred color pattern is retained more nearly 

 intact in the female than in the male, the opposite condition 

 holding for Fundiilns. 



6. The dark, ocellated spot, that, in Fnndiilns characterizes 

 the posterior rays of the dorsal fin of the male, is present here 

 only in the female, although the same area in the male is usually 

 more heavily pigmented than the rest of the fin in the male. 



7. The contact organs are similar in form and distribution to 

 those of Fitndulus. 



8. As in Fundiilns, all of the fins of the male are more deeply 

 and more brilliantly colored than in the female. 



