382 ORTMANN— THE ALLEGHENIAN DIVIDE. [April 18, 



cant at certain times in the past. But beginning with the Post- 

 cretaceous elevation of the country and the subsequent rejuvenation 

 of all drainage systems, this barrier has been emphasized again and 

 persists to the present time. 



3. The uniformity of the fauna of the upper Ohio basin is a 

 character acquired in Postglacial times, and it has been shown that 

 not only Big Sandy River, but also Licking River, and possibly also 

 Kentucky River, belong to the upper Ohio basin, and not to the 

 Cumberland-Tennessee drainage. In this case zoögeographical evi- 

 dence contributes to the solution of a question which has not been 

 fully settled by physio graphical methods. 



4. On the western side we have remnants of an older (F 're- 

 glacial) faunistic differentiation. The most important division is 

 the Tennessee-Cumberland fauna, of which, however, only a small 

 part has been considered in the present paper, and which deserves 

 more detailed study. Other remnants of what might be Preglacial 

 faunas are possibly seen in the headwaters of the Monongahela and 

 Kanawha rivers. But in these cases the physiographical develop- 

 ment of these parts must be studied more closely before we can 

 arrive at a final conclusion. 



5. The Atlantic fauna is a distinct fauna and the creation of two 

 faunal provinces, Mississippian and Atlantic (Simpson, 1900, p. 

 505), is fully justified. Nevertheless, the Atlantic fauna is a sec- 

 ondary one, derived originally from that of the interior basin, and 

 its chief character consists in the absence of a great number of types 

 of the interior basin. 



6. Within the Atlantic fauna we have to distinguish two main 

 elements, a northern and a southern. The northern came from the 

 interior basin around the northern end of the Alleghenies ; the south- 

 ern came around the southern end. The former belongs to the Pre- 

 glacial time, but is not very old, while in the latter there are some 

 rather ancient elements, going back possibly to the earlier Tertiary, 

 or even beyond. The southern element probably is closely connected 

 with the Tennessee-Coosa problem. 



7. Along the Atlantic slope we have a dispersal line directed both 

 north and south, which has been clearly recognized, for land-forms, 



