608 On the Distribution of Fresh- Water Fishes. (October, 
fishes, which have been drawn from my own experience as a col- 
lector. In these, I have had reference chiefly to the smaller or 
non-migratory species, the Centrarchide, Etheostomatide, and 
Cyprinide. The larger species are generally too little known 
or are too widely distributed to be especially considered here. 
The theoretical questions of how fishes have become dispersed, 
or how and why they have in past time extended their range, 
I do not propose to discuss. These points and others noticed 
below have been ably treated by Professor Cope. 
It may be premised that some of the propositions contained in 
the following pages are probably only half truths, to be more 
completely stated as our knowledge increases. 
I. In the case of rivers flowing into the ocean the character 
of the faune of the upper waters compared one with another 
bears no or very little relation with the places of discharge. An 
illustration of this may be taken in the general similarity of the 
faune of the Youghiogheny and Upper Potomac rivers, — or in 
the greater resemblance existing between the faunz of the Chat- 
tahoochee and Ocmulgee than between those of the Chatta- 
hoochee and Alabama. The Wisconsin River and the Red River 
of the north have a very similar fauna. 
II. River 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 the points of dis- 
charge, if in fresh water, the greater the resemblance. The al- 
most identical fauna of the Catawba and Saluda will exemplify 
this. ; : 
III. The higher or the older the water-shed between two 
- rivers, the fewer species are common to both. (This needs further 
investigation. ) ; 
V. Certain species — not including “ species of general dis- 
tribution” — occur on opposite sides of even the highest water- 
sheds. This fact was first noticed by Professor Cope. The a 
currence of Luzxilus coccogenis and Hybopsis rubricroceus mM P> 
Tallulah and Little Tennessee rivers will illustrate. Neither 
species is known as yet from any river basin other than the 
Savannah and Tennessee. The existence of Platygobis gracilis 
in the upper waters of the Missouri and Colorado is an ei 
illustration. ‘ 
V. When the water-shed between two streams is a swampy 
upland instead of a mountain range, the same species will 
1 Journal Acad. Nat. Sci., Phila., 1868, pp. 239-247. 
