EXPLANATIONS OF PHOTOGRAPHS IN PLates III-VII 
All photographs were taken through a phase-contrast 
microscope system. 
The 1X1” photographs are at a magnification of 1550. 
Se oD 
The 2”X2” photographs are at a magnification of 
4500; they are not enlargement of the smaller ones, but 
are of different grains, except for the fossil specimens. 
