REPORT OF THE STATE PALEONTOLOGIST 1902 999 



glomerate, at the base of the Cattaraugus beds. Here Carbonic 

 types appear, a new fauna is introduced and without attempt- 

 ing to analyze again the time values of the various components 

 (I have already discussed this point in my report of last year, 

 op. tit. p. 524) it is enough to add that while the withdrawal of 

 a large part of the Devonic fauna is concurrent with this new 

 arrival, it is altogether to be expected that certain Devonic 

 types survive. It will not do to state this condition as merely 

 an intermixture of Carbonic and Devonic organisms, a charac- 

 terization easily made and which would dismiss these beds as 

 " transitional " but it is rather the fact of a new arrival in the 

 field while survivors of the old faunas or superstitial species 

 still endure. The condition is normal for the process of replace- 

 ment of one fauna by another. It matters little if among the 

 superstitial species one remains so characteristic everywhere of 

 the later Devonic as Spirifer disjunctus; for not alone 

 in New York does this species transcend the limit of the Devonic 

 and enter the Carbonic. With proper regard for such modifica- 

 tions as additional evidence may require I am disposed to the 

 conviction that in placing the dividing line between Devonic 

 and Carbonic at the base of the Cattaraugus beds, as is done 

 on the geologic map, we have the support of the most direct 

 evidence. 



