1 86 NEW YORK STATE MUSEUM 



the Appalachian region, where there were varying conditions of sedimen- 

 tary deposition, than in the Cordilleran and continental border regions, 

 where these conditions were more uniform. Thus, in the eastern province, 

 as Professor Williams has pointed out, diversity and alternation of deposits 

 is accompanied by numerous successive and distinct faunas ; in the extreme 

 western regions, uniformity of prevailing calcareous sedimentation for long 

 periods is characterized by the abnormally long continuance of many 

 Devonic species ; and the central continental province, midway between 

 the two, is marked by the unmistakable recurrence of Devonic species well 

 along into the Carbonic. Another noteworthy feature of the Devonic 

 which has been developed very fully and clearly by the painstaking investi- 

 gation of Dr Clarke is that faunal changes within the ancient Appalachian 

 sea are sometimes so precisely indicated that it is possible, as in the case of 

 the Portage group, to trace the boundaries not only of local provinces, but 

 of local subprovinces characterizing the stage in question. Thus, the 

 Genesee province of the Portage is divided into Chautauquan and Naples 

 subprovinces on the basis of differences in their faunal facies ; and an inter- 

 esting peculiarity of the Naples subprovince is that, as stated by Dr Clarke, 

 " with contemporaneous faunas of the Appalachian gulf " its fauna " has in 

 its purity no organic relation, direct or sequential."' 



It is very necessary to understand this matter of the provincial charac- 

 ter of Devonic faunas in North America. Also, in tabulating the facts of 

 distribution, one must keep in mind the inferred lines of intercommunica- 

 tion between those provinces that were connected, as well as the position 

 of barriers between others that are known to have been separated. The 

 data upon which our information in regard to these matters reposes have 

 been brought together chiefly by workers In Invertebrate paleontology, and 

 as the evidence at their disposal is enormous as compared with that 

 obtained from a study of the vertebrates alone, no deductions drawn from 

 the latter are likely to prejudice the results depending upon a different class 



^ Clarke, J. M. The Naples Fauna in Western New York. N. Y. State Mus. Mem. 6. 

 1904. p. 382. 



