CONCLUSIO.NS. 91 



CONCLUSIONS.* 



la the course of the investigations detailed in this [)aper, some light 

 has been thrown on the laws which govern the distribution of fresh- 

 water fishes in general. The writer has collated the known facts into a 

 series of general propositions, which, without any pretense to exhaust- 

 iveness or to originality, are here briefly stated. It may be premised 

 that some of these i)ropositions are only half truths, to be more com- 

 pletely stated when our knowleiige of the subject shall be increased. 

 Most of the statements also refer chiefly to the smaller and non-migratory 

 fishes, es])ecially the EtheostomatidWj Ceiitrarchuhv, and Cijprinidw. Our 

 knowledge of the range of the larger Catostotnidte and tSUuridui is still 

 very meagre. 



For the first statement of several of the following propositions, we are 

 indebted to Professor Cope, who has ably discussed the subject of the 

 distribution of tishes in his paper on the Fishes of the Alleghany Ki'giou 

 of Southwest Virginia, Journ. Acad. Xat. Sc. Phila. 18G8, i)p. 239-247. 



I. In the case of rivers flowing into the ocean, the character ot the 

 faunae of the upper waters, ('om[)ared one with another, bears no, or 

 very little, relation with the places of discharge. In illustration of this 

 we may note {a) the similarity of the faunae of the Chattahoochee and 

 Altamaha, as com[)ared with the Chattahoochee and Alabama. The 

 faunae of Wisconsin River and of Ked Itiver of the North are very similar. 



II. Iiiiver- basins having a similar discharge into some larger river or 

 lake have a similarity of fauna, due to this fact, and, in general, other 

 things being equal, the nearer together the jjhices of discharge, if in 

 /resli water, the greater the similarity. The almost identical faunae of 

 the Catawba and the Saluda will illustrate this. 



III. Parallel rivers tributary to the same stream have, other things 

 being equal, more in common than streams coming from opposite direc- 

 tions. The Wabash and jMiami have more in common than either has 

 with the Kentucky. 



IV. The higher or the older the water-shed between two streams, the 

 fewer species are common to both. (This matter needs lurther investi- 

 gation.) 



V. Certain species, not including "species of general distribution", 

 occur on opposite sides of even the highest watersheds. This fact was 

 first noticed by Professor Cope. The occMirrence of Luxilus eoccofjenis, 



* An abstract of the icniaiiiing part of thia paper appeart-*! in the American Naturalist 

 for October, 1877 (p^). ()()7-()l:)). For tbia part, Professor Jordan is alone responsible. 



