19 



the presence of trout in the upper Chattahoochee, we must 

 account in some other way. 



It is noteworthy that the upland fishes are nearly the same 

 in all these streams, until we reach the southern limit of possible 

 glacial influence. South of western North Carolina, the faunae 

 of the different river basins appear to be more distinct from one 

 another. Certain ripple-loving types* are represented by 

 closely related but unquestionably different species in each 

 river basin, and it would appear that a thorough mingling of 

 the upland species in these rivers has never taken place. 



With the lowland species of the Southern rivers it is differ- 

 ent. Few of these are confined within narrow limits. The 

 streams of the' whole South Atlantic and Gulf Coast flow into 

 shallow bays, mostly bounded by sand-spits or sand-bars which 

 the rivers themselves have brought down. In these bays the 

 waters are often neither fresh nor salt ; or rather, they are 

 alternately fresh and salt, the former condition being that of 

 the winter and spring. Many species descend into these bays, 

 thus finding every facility for transfer from river to river. There 

 is a continuous inland passage in fresh or brackish waters, tra- 

 versable by such fishes, from Chesapeake Bay nearly to Cape 

 Fear ; and similar conditions exist on the coasts of Louisiana, 

 Texas, and much of Florida. In Perdido Bay I have found 

 fresh-water mmnows {Notropis c erco stigma ; Notropis xcenoceph- 

 al?is), and silversides [Labidesthes siccidiis), living together 

 with marine gobies i^Gobiosoma molestnm) and salt-water eels 

 { My r op his punctatiis). Fresh- water alligator gars {Lepisosteus 

 tristcechus) and marine sharks compete for the garbage thrown 

 over from the Pensacola wharves. In Lake Pontchartrain the 



* The best examples of this are the following : In the Santee basin are found Notropis pyrrhotn- 

 elas, Notropis niveus, and Notropis chloristius : in the Altamaha, Notropis xcEnurus and Notropis 

 callisemus ; in the Chattahoochee, Notropis hypselopterus and Notropis eurystomus : in the 

 Alabama, Notropis coeruleus, Notropis trichroistius, and Notropis callistius. In the Alabama, 

 Escambia, Pearl, and numerous other rivers, is found Notropis cercostigtna. This species 

 descends to the sea in the cool streams of the pine-woods. Its range is wider than that of the others, 

 and in the rivers of Texas it reappears in the form of a scarcely distinct variety, Notropis venustus. 

 In the Tennessee and Cumberland, and in the rivers of the Ozark range, is Notropis galactur us: and 

 in the upper Arkansas Notropis camurus — all distinct species of the same general type. Northward, 

 in all the streams from the Potomac to the Oswego, and westward to the Des Moines and the 

 Arkansas occurs a single species of this type, Notropis whipplei. But this speci«s is not known 

 from any of the streams inhabited by any of the other species mentioned, although very likely it is 

 the parent stock of them all. 



