NAPLES FAUNA IN WESTERN NEW YORK, PART 2 203 



thereafter, with a brief interval of gray muds, appears a second black 

 band of great thickness (227 feet; in Ontario county but 21 feet in 

 thickness) separated from a bituminous band above by an interval of 

 257 feet of muds and sands. And again at a still higher horizon on 

 Lake Erie is a third black band altogether absent in sections farther 

 east. Doubtless the increase westward in the number and thickness of 

 these bituminous deposits indicates the prevalence thither of the deeper 

 waters of a now well inclosed sea, as indicated by their predominance in 

 northern Ohio and in the vicinity of Kettle Point, Ontario, in both regions 

 to the essential exclusion of the gray muds with their characteristic 

 fauna. 



The nature of the calcareous banks in these bituminous muds invites 

 further attention. The Styliola or Genundewa limestone is a thin sheet 

 sometimes interrupted, sometimes nodular, but virtually continuous from 

 Lake Erie to Seneca lake. It is for the most part a mass of exuviae of the 

 pteropod Styliolina fissurella and in many places bears little trace 

 of intermixture of sedimentary mud. It carries with it species of the 

 Naples fauna which now make their earliest appearance, goniatites, lamelli- 

 branchs and gastropods, and we have frequently cited this occurrence as 

 illustrative of a p'renuncial fauna. But notwithstanding the presence of 

 various molluscan shells the mass is essentially a pteropod ooze. Now the 

 existing pteropods are pelagic creatures of surface or zonal habit, rising to 

 the top of the water or -swimming below it much according to the time of 

 day 1 and for the most part the shelled species are warm water or tropic 

 forms; with but one or two exceptions cold water species are shell-less 2 ; 

 moreover the distribution of the dead shells on the sea bottom, says Wal- 

 ther, 3 corresponds to the distribution of the living animals on the sea surface. 



There is no reason to doubt the pteropod nature of the needlelike 

 shells of Styliolina fissurella, the essential component of the 



1 Thomson, W. The Atlantic. 1878. p. 125. 



2 Murray & Renard. Challenger; Deep Sea Deposits, p. 224. 

 3Walther. Einleitung, p. 507. 



