Clarke — The Naples Fai na. 139 



Independence shales), and present evidence shows the occurrence of Monti- 

 cooeras intmnesoens in both. 



The facts cited afford evidence of a feeble representation of the fauna of 

 the Intumescens-zone in Iowa and the far north-west, but without the associa- 

 tion of species characteristic of that fauna in its most specialized development 

 as shown in western New York and in Westphalia. On the other hand, they 

 indicate that this single index fossil. Mantle intumescens. will prove to be 

 involved with a fauna of quite different facies, as in many of its European 

 occurrences ; Devonshire, the Hartz, the Urals. 



At a later opportunity Ave may take up for consideration the hypotheses 

 which have been put forth with regard to the dispersion of our upper Devonian 

 faunas. The)' are serving a temporary purpose in the absence of facts and 

 wiser fancies. 



But for the Intumescens-fauna alone, meager as the extrinsic evidence is, 

 it suffices to indicate the strong probability of an invasion into its New York 

 province from the west and northwest. Intrinsic evidence is to the same 

 intent; the wedge-like interpenetration of the Otselic fauna at the east of the 

 Intumescens province is sufficient proof. At its incoming the fauna seems to 

 have been weak in the goniatitine element and herein to have rapidly 

 developed great strength and diversity. The present evidence indicates that 

 the goniatite element itself is accelerated. Nothing of it is known within 800 

 miles of its New York province. It must have entered its province in simple 

 form ; otherwise, with so varied an aspect as that here portrayed, it should have 

 left a clearer trace behind. The acceleration of many of its species we have 

 also noted. 



The evidence before us shows to how higdi a decrree the confined sea 

 wherein this organic association flourished had become, a center of variation, 

 and even of origination of organic types. 



