THE NAPLES FAUNA 



(FAUNA WITH MANTICOCERAS INTUMESCENS) 

 IN WESTERN NEW YORK. 



By John M. Clarke. 



Geological Introduction. 



The time period characterized by the culmination of the cephalopod 

 species, Manticoc&ras intumescem, Beyrich, is clearly denned in many coun- 

 tries and is commonly regarded as marking an early stage in the closing 

 phases of Devonian life and time. 



The assemblage of species manifested in the several local developments 

 of this zone of life forms is found to be variable within certain limitations. 

 That which we are about to consider, to which we have previously applied 

 the term Naples fatma, presents numerous traits which bring it into close 

 relationship to the Intumescens-zone of Devon, Belgium, the Rhine, the Hartz, 

 and the west and east slopes of the Urals. In none of these, however, are its indi- 

 vidual, specific and generic features so fully reproduced as in the association 

 described by Holzapfel* as occurring at Martenberg, near Adorf, in 

 Westphalia. 



This Intumescens-fauna has clearly manifested itself in cisatlantic palaeo- 

 zoic provinces only in the western part of the State of New York ; in passing 

 westward from the meridian of Cayuga lake its distinctive organic features 

 become gradually disentangled and isolated from the' dissimilar but geologic- 

 ally contemporaneous eastward fauna ; they become predominant throughout 

 Ontario, Livingston, Genesee and Wyoming counties ; still further westward 

 its faunules gradually become less prolific, decline in unity and, so far as our 

 observations now extend, no evidence of the assemblage has been found beyond 

 the western boundary of this State. 



* PalaeoDtographlca Neue Folge, vol. viil, 6, xxvhi. 1882. 

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