CONCLUSIONS. 91 



CONCLUSIONS.* 



In the course of the investigations detailed in this paper, 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 propositions are only half truths, to be more com- 

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

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

 fishes, especially the Etheostomatidce, Ccntrarchidce, and Cyprinidw. Our 

 knowledge of the range of the larger Catostomidw and Siluridce 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 fishes in his paper on the Fishes of the Alleghauy Region 

 of Southwest Virginia, Jonrn. Acad. Nat. Sc. Phila. 3868, pp. 239-247. 



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

 faunae of the upper waters, compared 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 Chattahoocheo and 

 Altumaha, as compared with the Chattahoochee and Alabama. The 

 faunte of Wisconsin Elver and of Red liiver of the North are very similar. 



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

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

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

 fresh icc.ter, 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 Miami have more in common than either has 

 with the Kentucky. 



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

 lower species are common to both. (This matter needs turther 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 occurrence of Luxilus coccogenis, 



* Au abstract of the remaining part of this paper appeared in the American Naturalist 

 for October, 1877 (pp. G07-til3). For this part, Professor Jordan is alone responsible. 



