220 TRANSACTIONS OF THE [MaY 15 



while those at Eoilly Pond and Big Crooked Lake have been 

 estimated at more than a million cubic yards eacli. 



The character of the Hinckley eartli, as disclosed by the 

 microscope, and probably that of all the other earths referred 

 to, is not materially different from that of a hundred deposits 

 found throughout the glacial region of New England, excepting 

 that this Herkimer county earth appears to be much purer than 

 any other known diatomaceous deposit, both in the number of 

 unbroken forms found in it, and in its freedom from sand and 

 other foreign material. Identifications have been made of 

 eleven genera and about forty species of Diatomacese, of which 

 more than thirty species are of the genera Navicula, Stau7-oneis, 

 Cymbella and Ennolia, which are almost always prominent in 

 the lacustrine deposits of our northern States. These are all 

 solitary and motile forms, indicative of a still water habitat, as 

 distinguished from those filamentous forms like Melo><ira, which 

 are characteristic of running water, and those sessile forms 

 like Goscinodiscus and Arachnoidiscus, which are characteristic 

 of the seashore. 



The discovery of these Herkimer county deposits has its main 

 value in the relation which it establishes between the glacial 

 lake region of the Adirondacks and similar geological forma- 

 tions in other parts of the country. A careful comparison of 

 all diatomaceous deposits on this continent would lead to 

 results of considerable importance, and this is a field of research 

 which has been heretofore generally neglected. 



May 15, 1893. 

 Stated Meeting. 



President Bolton in the chair, and sixty persons present. 



Dr. Edward G. Love delivered the eighth lecture of the 

 Public Lecture Course, 1892-1893, on "Photographing Micro- 

 scopic Objects," illustrated by lantern slides, apparatus and 

 photographs. 



