384 
BULLETIN OF THE BUREAU OF FISHERIES. 
sackusetts Bay, it is not likely that the vernal flowerings become active there until 
after the middle of March — -that is, at least three weeks later than in the waters be- 
tween Cape Ann and Cape Elizabeth, or in Cape Cod Bay (p. 396). 
Fig. 104. — Distribution of the more characteristic types of phytoplankton, February to March, 1920. 1 , rich diatom; 
2, sparse diatom; 3, sparse Ceratium and diatom 
The shallow waters off western and southern Nova Scotia, out to and including 
German and Browns Banks, are the site of a second center of propagation for dia- 
toms late in March, for though the phytoplankton was still very scanty there on 
