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THE GEOGRAPHICAL DISTRIBUTION OF FISHES. 



There are known at the present about 

 twenty thousand species of fishes, which 

 are distributed throughout the creeks, 

 rivers, lakes, seas and oceans of the 

 world. A few species of the open sea are 

 cosmopolitan ; the others are more or 

 less restricted in their range. Northern 

 Asia, Europe and North America have 

 in common a few species of fresh water 

 fishes. There are many others of close 

 relationship, which indicates a somewhat 

 common origin of the fish faunas. The 

 same is largely true of the salt water 

 shore fishes, which live well to the north. 

 The fresh water fishes of South America, 

 Africa and Australia are all different from 

 each other, none being even closely re- 

 lated as are those we find in the coun- 

 tries of the northern hemisphere. 



The fishes of our Atlantic coast are 

 different from those of the Pacific, very 

 few species being common to both coasts. 

 The fishes of the Ohio river are entirely 

 different from those of the Columbia, not 

 a single species being common to both 

 streams. The fishes of the Missouri river 

 are very different from the Ohio, many 

 of the larger species, as catfishes, buffa- 

 lo fishes, black basses, and some of the 

 sun fishes are common to both rivers. 

 The difference between the fishes of these 

 two rivers is chiefly in the smaller kinds, 

 which do not migrate to any great extent, 

 and is greater as you go toward their 

 sources, or confine yourself to their 

 smaller tributaries. 



There are many reasons why the fishes 

 of one region are not the same as those 

 we find in another. Some of these rea- 

 sons we may learn by making a careful 

 study of the fishes of each region, and 

 their environment. In addition we must 

 learn all we can about the past history of 

 the country, finding which streams were 

 formed first, and how they became in- 

 habited from the old ancient fish faunas 

 of our earher geological periods. If you 

 visit streams in the Alleghanies, the 

 Ozarks and the Black Hills you will find 

 them much alike. All have clear, cool 

 water, flowing over sand or gravel. The 

 black bass, speckled trout, channel cat, 



and the eastern pickerel will live quite as 

 well in streams of each locality. If you 

 spend a day at each place collecting 

 fishes all your catch will not be the same 

 species. In the Alleghany region you 

 will obtain about forty species, and a like 

 number in the Ozarks. Of these quite 

 one-fourth, or one-fifth, will be the same 

 species, and the others closely related. A 

 large portion will consist of sunfishes and 

 very small, perch-like fishes, which are 

 called darters. These are spiny-rayed 

 fishes ; that is, nearly all of the fins are 

 made partly of strong, sharp spines, such 

 as you find on the back of sunfishes, 

 black bass and the like. In the streams 

 of the Black Hills you will not find more 

 than fifteen species, and not more than 

 one or two, if any, will be the same as in 

 either of the other two catches. There 

 are none of the spiny-rayed fishes in the 

 Black Hills, and no trout, though the 

 streams seem in every way well suited for 

 them. The fishes of the Black Hills con- 

 sist of two catfishes, four suckers, eight 

 minnows, and one member of the cod 

 family. Why are there no spiny-rayed 

 fishes? If you examine a map you will 

 find that the Black Hills is an isolated re- 

 gion, about seventy-five by one hundred 

 miles in extent. It is covered with heavy 

 pine forests and drained by a dozen or 

 more good-sized creeks, which find, 

 through the north and south forks of the 

 Cheyenne, an outlet into the Missouri 

 river. Surrounding the Black Hills is a 

 broad plain one hvmdred or two hundred 

 miles in width. It has no forests, and 

 only a scant vegetation. Its streams are 

 alkali and contain much solid matter in 

 suspension. None of these streams flow 

 over rocky or gravelly beds. Like all the 

 streams of the great plains they are over- 

 loaded with sediment. All the streams 

 can do with this sediment is to deposit it 

 in places during falling or low water, and 

 in time of freshets, pick it up, shift it 

 about and redeposit it farther down the 

 stream. Such streams are like the Platte, 

 narrow and deep in a few places, but 

 mostly wide and shallow\ with a bottom 

 of quicksand. The streams of the plains 



