460 



A, W. GRABAU THE SHERBURNE SANDSTONE 



The 17 species starred in the foregoing table are given by AVilliams"^ 

 as dominant species of the Ithaca fanna at Ithaca. Three others of that 

 list do not occur in the eastern Ithaca. These are : 



Paleoneilo fllosa. 

 (Jystodictya meeki. 

 Orthoceras l)el:)ryx var. cayuga. 



The 12 species marked by a dagger (f ) are considered by AYilliams the 

 dominant types of the eastern extension of the Ithaca fanna. It will l3e 

 observed that 6, or half of the number, are also dominant at Ithaca, the 

 remaining 6 being typical Hamilton species. The double dagger (|)* 

 indicates species of the Traverse fanna of Michigan and Iowa, also marked 

 xt in Table III. 



j2] 



Where the numbers in the columns are double, as <-\-y,OT 2 -\- 1, the 



uJ 



first, or upper, figure refers to the number specifically identified, the sec- 

 ond, or lower, figure to the number doubtfully identified. 



Table IV. — Summary of Species of Ithaca Fauna of Chenango and Cortland 

 Counties {Clarke's Lists) 



Classes. 











Late 



Number 



Eastern 



Traverse 



True 



Ithaca 



of 



Hamilton 



immi- 



Ithaca 



or 



species. 



forms. 



grants. 



forms. 



Chemung; 

 forms. 



Naples 

 immi- 

 grants. 



Aiitliozoa 1 



Bryozoa 1 



Bracliiopoda 29 



Pelecypoda 37 



Gastropoda and Ptero- 



poda 9 



Cephalopoda 3 



Crustacea 3 



Crinoidea 3 



Total 86 



Percentage 100. 



21 

 29 



2 

 1? 



60 

 69.77 



10 

 11.63 



6.98 



8.14 



This summary shows the predominant Hamilton character of this 

 fauna, nearly 70 per cent of the species being of this origin. Of the 

 Ithaca forms, which include both of those Ithaca species which are found 

 in the type region and the "late Ithaca," which have so far been found 

 only in the Chemung, there are 18.61 per cent, or 16 species, as com- 



Bull. U. S. Geol. Survey, 210, p. 74. 



