198 



Puget Sound Marine Sta. Pub. 



Vol. 1, No. 17 



Spirogyra gigantica, n. sp. 



Grace A. Hill, University of Washington, Seattle. 



Filaments 173 to 188 /x in diameter. Cells 1-2 diameters long, or 

 slightly more or less. Chloroplasts not fewer than 4 and not more than 

 6, roughly parallel to each other, deviating from transverse by an angle 

 of 10-25 degrees, making 1.5-3 turns in the cell, 15-22 fx wide, lobed at 

 margin; pyrenoids conspicuous, 7-12 /x in diameter, 9-12 in each half- 

 turn. Reproduction unknown. 



So named on account of its large size. Collected by A. M. Hurd in 

 basin of old fountain on University of Washington campus, Seattle, Wash., 

 Nov., 1916. 



It resembles S. crassa Kiitz., but differs as follows: 



A. S. crassa — Cells 150-160 yu, wide; chloroplasts .5-1 turn in the cell; 



pyrenoids 'i-7 /a in diameter. 

 AA. S. gigantica — Cells 173-188 /u. wide; chloroplasts 1.6-3 turns in the 



cell; pyrenoids 7-12 /x in diameter. 



I ^s."^ J J 



1 ^ 



G. A. Hill, Del. 



PLATE S3 



Fig. 1. Cells about ready to divide. X 70. 



Fig. 2. Cell recently divided, and thus short. X 32{ 



