32 



Repokt of the State Geologist. 



This peculiar association is not only distinctively different in its organic 

 elements from the faunas which immediately precede and follow it, but also 

 from those contemporaneous with it in adjacent regions. 



The formation in which this fauna is involved, the Portage grqup, was 

 defined more than a half century ago by Professor James Hall, its boundaries 

 were set, its westward extent determined, and, at various times since, several 

 of its species described. Some further accounts of its geologic relations and 

 organic constitution have been given by others, especially during the past 

 twelve years.* 



For the purpose of apprehending the stratigraphic conditions in which 

 this fauna is involved, they are briefly restated in the following pages. As 

 many of the important species of the fauna, with the exception of those here 

 especially considered, are still undescribed, previous studies have been prose- 

 cuted at somewhat of a disadvantage. This paper is an introductory instalment 

 of what is hoped may prove a reasonably full presentation of the organic 

 components of this zone. 



The succession of strata exhibited in a series of beautiful exposures along 

 the course of the Genesee river was described in some detail by Professor 

 James Hall in the fourth "Annual Report of the Survey of the Fourth 

 Geological District of New York" (1840). 



* The original accounts of this formation are found in the following reports : 

 James Hall, Annual Report on the Survey of the Fourth Geological District, 1840. 

 Ditto, Geology of New York: Report of the Fourth Geological District, 1848. 



Later publications in which especial consideration is given to these rocks and their contents, are : 

 James Hall, Palaeontology of New York, vol. 1 , 1884-5 ; part 2, 1879. 



John M. Clarke, On the Higher Devonian Faunas of Ontario County, N. Y. ; Bull. No. 16, U. S. Oeol. Surv., pp. 1-78, 

 pis. 1-3, 1885. 



Ditto, A Brief Outline of the Geological Succession in Ontario County, N. Y.; Fourth Ann. Rept. State Geo!., pp. 

 9-22, 1885. 



Ditto, Die Fauna mit Goniatites intumescens, Beyrich, im westlichen New York ; Neue.t Jahrb. fiir Mineral., 1891, 

 Bnd. 1, pp. 161-168. 



Ditto, The Fauna with Goniatites intum«scens, Beyrich, in western New York ; American Geologist, Aug. 1891, pp. 86-105, 

 Ditto, The Diicovery of Clymenia in the Fauna of the Intumescens zone (Naples beds) of western New York, and iu. 

 geological significance , Amer. Jour Science, vol. xliii, pp 57-52, 1892. 



Ditto, The Protoconch of Orthoceras ; American Geologist, vol. xii, pp. 112-117, 1893. 



Ditto, The Genus Autodetus and some paramorphic shells from the Devonian ; American Geologist, May, 1894. 



Ditto, Report on Field Work in Chenango County ; Thirteenth Ann. Rept. N Y. State Geologist, pp. 531-557, 1894. 



Ditto. The Stratigraphic and Faunal Relations of the Oneonta sandstone and shales, the Ithaca and Portage Groups in 

 central New York ; Fifteenth Ann. Rept. N. Y. State Geol., pp. 29-81, 1898. 



Ditto, The Geologic Conditions at the Site of the proposed Dam and Storage Reservoir on the Genesee River at Portage; 

 Rept. State Engineer and Surveyor for 1896, pp. 116-122, 3897. 



H. S. Williams, On the Fossil Faunas of the Upper Devonian, along the meridian of 76° 30', lrom Tompkins county, New 

 York, to Bradford county, Pennsylvania. Bull. No. 8, U. S. Geol. Surv., pp. 1-36. 1884. 



Ditto, The Fossil Faunas of the Upper Devonian : The Genesee section, New York ; Bull No. 41, U S. Geol. Surv., pp. 

 1-123, pis. 1-4, 1887. 



Ditto, Correlation Papers— Devonian and Carboniferous ; Bull, No. 80, U. S. Geol. Surv. pp. 1-279, 1891. 



Charles S. Prosser, The Thickness of the Devonian and Silurian Rocks of western central New York ; American 

 Geologist, Oct. 1890, pp. 901-211. 



Ditto, The Thickness of the Devonian and Silurian Rocks of western New York, approximately along the line of the 

 Genesee river; Proc. Rochester Acad. Sciences, vol. 2, pp. 49-104, 1892. 



Ditto, The Thickness of the Devonian and Silurian Rocks of Central New York; Bui!. Geol. Soc. Amer.,vo\. 4, pp. 91-118, 1893 



D. D Luther, Report on the Geology of the Livonia Salt Shaft ; Thirteenth Ann. Rept. N. Y. State Geol., pp. 21-130, 1894. 



