220 TRANSACTIONS OF THE [May 15 
while those at Roilly Pond and Big Crooked Lake have been 
estimated at more than a million cubic yards each. 
The character of the Hinckley earth, 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 Diatomacez, of which 
more than thirty species are of the genera Navicula, Stauroneis, 
Cymbella and Eunstia, 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 Melosira, which 
are characteristic of running water, and those sessile forms 
like Coscinodiscus 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. 
Statep Meretina. 
President Botton 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. 
