■ 2lQ NEW YORK STATE MUSEUM 



The fauna of this province is indigenous. Prolonged study of its compo- 

 sition shows it to be at the outset the fauna of the Hamilton stage. It is 

 the autochthonous fauna of this period, having been on the ground during 

 Hamilton time. The modifications which supervened on the species as 

 time passed, gradually changed the face of the organic association, so that 

 eventually the species individually and the fauna as a whole became 

 impressed with a character quite their own.' 



3 Genesee province. From the interleaved strata along the meridian of 

 Cayuga lake, the field westward to Lake Erie is occupied by softer shales 

 with interbedded and overlying sands, the former embodying locally two or 

 three noteworthy bands of bituminous shales, repetitive expressions of the 

 Genesee shale beneath. The Genesee province contained a fauna which 

 was (as we have previously demonstrated) wholly a newcomer into the 

 gulf from the northwest, an invasion by way of a brief submergence of the 

 western old shore line; a world-wide traveler, it has maintained with 

 surprising integrity its individuality on its long journey eastward from 

 middle Germany into Russia and Siberia and down through British 

 America (Manitoba). Its stay was brief, and with its disappearance the 

 Appalachian sea was again shut off at the west. It is the fauna of the zone 

 of Manticoceras intumescens, or, speaking geographically, the 

 Naples fauna. Its earlier species penetrated as far eastward as Cayuga 

 lake, but here the invasion ended, as the field was occupied by a resistant 

 aggregation, the Ithaca fauna 1 ; the invaders seem to have been finally 

 driven to exile by the outburst and aggression of the Chemung fauna. 

 Some of its associated species, specially those which seem to have ancestral 

 relations with the antecedent Hamilton fauna, extend eastward in the inter- 

 leaves of the Ithaca province, but occurrences of this kind are rare. 

 Within the fauna of this Genesee province are two evident congeries, one 

 an advance guard of the invasion, which extended to the eastern limit of 



-A very few of the commoner forms of the fauna which may have been derived from 

 the Hamilton stage beneath, occur at points still farther east, in the 200 feet of strata 

 immediately overlying the Genesee shales. 



