3 5° 



NEW YORK STATE MUSEUM 



DEVELOPMENT OF THE INTUMESCENS FAUNA OUTSIDE OF NEW YORK 

 A very notable feature of the Upper Devonic deposits of the conti- 

 nent of Europe is the clearness of its subdivision by facies. This is 

 specially appertinent to the ammonitoid 1 faunas, and it is indeed essentially 

 on these that this subdivision has been elaborated. This facial division, so 

 far as based on the ammonoids, is quite generally regarded as sequential 

 in time rather than an expression of geographic variants, unlike the varia- 

 tions in facies represented by the Naples, Ithaca and Oneonta faunas of 

 Portage time in New York. Encroachments are recognized of indicial 

 ammonoids into contemporaneous areas of brachiopod and coral growth, as 

 in the case of Manticoceras intumescens in the Iberg reef lime- 

 stone at various sections. Throughout the succession positive time values 

 attach to leading species, though such species are not restricted to their 

 climacteric horizon. We shall presently advert to the considerable disturb- 

 ance in the New York province of the chronologic values of such of those 

 Eurasian species or their allies as are represented here. Spirifer dis- 

 junctus in the continental sections ranges from the upper Middle 

 Devonic into the Culm 2 ; it is found as a member of the Cuboides zone, a 

 straggler into the true ammonoid facies of the Intumescens zone, but still 

 its climacteric is in the brachiopod facies of this and the succeeding stages. 

 Herein the acme of the species both in Eurasia and America is quantiva- 

 lent, though in the latter it does not precede the Intumescens zone, while 

 recent investigations 3 indicate that it may ascend, as in Europe, into strata 

 which may properly be construed as Carbonic. To bring this facies devel- 

 opment of the Eurasian Upper Devonic before the eye, we present the fol- 



• 



lowing tabulation, compiled from various authors, with the help afforded by 



1 The German writers frequently apply the term pelagic to this association, but prob- 

 ably this term is, as we have before observed, not fully justified. 



2 The Culm is now regarded by Holzapfel and others as a deeper water facies of 

 the Coal Measures rather than a subsidiary member of the Carbonic. The presence of 

 Spirifer disjunctus in strata subsequent to the introduction of the Carbonic 

 fauna is noted by Drevermann. 



3 See N. Y, State Pal. Rep't 1901. 



