//. S, H "(II (<un. v — f) t vonian System of Devonshire, 'M 



pean sections are not common with us. The acuminata and 

 pugntu types of RhynchoneUa are known to ua at the base of 

 the eastern Chemung terrane, in Iowa at a doubtfully deter- 

 mined horizon, and in other western localities in association 

 with Carboniferous faunas. In England and Europe they are 

 conspicuous in association with what, are called " Middle Devo- 

 nian" faunas. Spirifera disjuncta is with them a Middle, as 

 well as Upper, Devonian form. With us it is characteristic of 

 the final Upper Devonian fauna alone. 



A comparison of the fauna of the Upper Devonian of North 

 Devonshire with our Devonian fossils shows that it is repre- 

 sented by our Chemung fauna, and although there are indica- 

 tions that it is a later fauna, as in its Productus with a row of 

 strong spines along the center ("Prod, curtinotus" T. M. 

 Hall), the ordinary forms are " Productus (or 8t?>ophalosi<i) 

 productoidee^ and " Chonetes //ardrensis" The Carbonif- 

 erous aspect of this Pilton fauna is not more marked than the 

 Upper Devonian aspect of the fauna of the limestones of Ilfra- 

 combe and Xewton. 



Comparison of these European Devonian sections and their 

 fossils with the corresponding ones of the Appalachian basin 

 leads me to the hypothesis that the marine faunas of the De- 

 vonian had different histories in the two areas. There is a 

 continuity in the succession from the lowest to the highest 

 faunas of the system in Europe which we do not find in the 

 American series. The explanation which seems to me most 

 probable is that the Middle and Upper Devonian faunas of 

 Europe (probably also down to the Lower Devonian fauna) 

 were merely successive stages of the life inhabitants of a com- 

 mon and more or less continuous basin. That during this 

 period the Appalachian basin was bounded on the east by a 

 considerable barrier and was partially separated from the cen- 

 tral continental basin by the Cincinnati uplift. 



Up to the close of the Hamilton the Devonian faunas in the 

 Appalachian and in the Central North American basin were 

 extensions of the same general fauna, but they differed mark- 

 edly from the corresponding European faunas. 



With the Tully limestone an incursion of species of the 

 European fauna began, and the following Chemung fauna 

 shows a resemblance to the Upper Devonian of Europe, es- 

 pecially in those species which were present, themselves 

 or in their ancestral representatives, in the European Mid- 

 dle Devonian. In the sections along the central part of 

 the Appalachian basin where the Tully limestone appears 

 holding the European "Cuboides" fauna, the Hamilton fauna 

 is abruptly stopped, but on the eastern side of the basin the 

 Hamilton appears to continue on, even mingling with the few 



