6 THE CYPRINODONTS. 



Between the sexes in certain species of these fishes there are great differ- 

 ences in size and shapes ; commonly the female is larger and less modified. 

 The greater number belong to the fresh waters ; many are inhabitants of 

 brackish water or of the sea along the shores. 



In the new world the known distribution extends from the basin of the 

 great lakes and British America on the north to Argentina and Chili on the 

 south, and from the Pacific to the West Indies and the Bermudas ; in the old 

 Avorld it comprises the whole of Africa, Madagascar, the Seychelles, and the 

 southern portions of Europe and Asia, from Spain to India and Japan. 

 Marine species are known only near the surface ; fresh water species carry 

 the vertical distribution from the sea level up to altitudes of 13,000 feet 

 or more ; the highest points reached by any of the fishes. 



Brownish or olivaceous, more or less tinted with greenish or yellowish, 

 prevail in the ground colors. Metallic tints, especially those of silver, are 

 common, most on the males. Apparently some of the species, or individuals, 

 pass from the fresh to the salt waters ; on these a change in the coloration 

 obtains similar to that affecting Salmo salar, which in the land-locked stage, 

 so called, is more brown with numerous spots of black, but which on reach- 

 ing the sea becomes more silvery with obsolescent spots. This modification 

 is marked in the common minnows of the Gulf coast, Fundulus grandis, and 

 in F. heteroclitus, from the Gulf northward along the eastern coasts of the 

 United States. Another variation is exemplified by F. heteroclitus, a general 

 diffusion of brownish with corresponding decrease in the amoimt of silver, or 

 in the brilliancy of coloration ; this is noticeable on comparing the more 

 modest coloi'ation of the variety, badius, from Grand Menan with the more 

 ornate representatives of the species from South Carolina to Florida. The 

 male is the more highly colored of the sexes. Of some species the males are 

 brilliant with striking combinations of red, orange, yellow, green, blue, gold, 

 silver, white, or black, several of which colors sometimes unite in producing 

 marked contrasts as compared with the plainer garb of the females. The 

 fins of some of the males resemble the wings of gorgeous butterflies, in 

 Mollienisia for instance. Among birds the female is commonly more modest 

 in color than the male ; this according to the Darwinian is beneficial, in that 

 it renders the female less conspicuous when nesting ; whether the benefit 

 caused the difference is another question. Females of these fishes also are 

 less conspicuous than the males ; but necessarily the fact in this case is pro- 

 vocative of some other theory in explanation. Considerable changes in color- 



