Trofidoi.f.ptus Fauna at Canakdaigua T.akk, N. V. 153 



addition to Professor Prosser's lists from eastern New York, unpub- 

 lished lists made by Miss (zrace Goodenough from the section at 

 Worcester, Otsego county, and by various members of the Cornell 

 Summer School of Field (ieology, from East Berne, Albany county, 

 were incorporated in the table. 



The Canandaigua Lake faunule consists of about 115 species which 

 are divided among the classes as follows : 



Crustacea 16 



Cephalopoda i 



Gastropoda 8 



Pteropoda 3 



Pelecypoda 16 



Brachiopoda 39 



Biyozoa 18 



Vermes 6 



Anthozoa 5 



It will at once be seen from the large number of Bryozoa and corals 

 and the small number of pelecypods that this fauna is not closely re- 

 lated to the fauna of the eastern counties. 



In Prosser's list from eastern New York there are 131 species which 

 can be definitely located at a certain number of feet from the top or 

 bottom of the Hamilton section of the region. Of this list 66, almost 

 exactly half, are pelecypods, while only 14 per cent, of the species in 

 our faunule belong to that class. It is well known that the more 

 western sections contain a smaller proportion of lamellibranchs than 

 the eastern ones, but our faunule contains less than one would expect 

 from its locality. 



The Livonia section, which is only 20 miles to the west, contains 30 

 per cent, of pelecypods in its list of species, and the Cayuga Lake 

 section about 30 miles east, has 32 per cent. Of course this is a com- 

 parison of one faunule with an aggregate of faunules, but it shows that 

 conditions were unfavorable for the development of lamellibranchs at 

 the time these strata were deposited. 



Of the 112 species identified, 26 are found in none of the other 

 sections, and so are not useful in comparisons. These are distribu- 

 ted as follows : Yermes, 3 ; Bryozoa, 6 ; Brachiopoda, 2 ; Pelecypoda, 

 2 ; Pteropoda, 1 ; Crustacea, 12. These are all rare or delicate species, 

 usually small and are not apt to be obtained in ordinary collecting from 

 sections. Of the remaining 86 species, 55 occur in that part of the 



