368 TUFTS COLLEGE STUDIES, VOL. II, No. 3 



like, with several pyrenoids; asexual reproduction by zoospores, 

 many in a cell, obovoid, extending into a long projection below, 

 and with 4 cilia above ; also by akinetes formed by the break- 

 ing up of the filaments into individual cells, with thick wall, 

 either producing new filaments or zoospores ; sexual reproduc- 

 tion by biciliate gametes. Marine. 



For discussion of the question of the claims of the generic 

 names Hormiscia and Urospora, see Hazen, 1902, p. 147. 



KEY TO THE SPECIES OF HORMISCIA. 



i. Filaments distinctly clavate. 2. 



i. Filaments nearly cylindrical. 4. 



2. Cells, except at extreme base, always wider than long. 



4. H. crassa. 



2. Cells never shorter than width. 3. 



3. Greatest diameter 135 M. 5- H. incrassala. 



3. Greatest diameter 500 p.. 2. H. Worinskjoldii. 



4. Filaments cylindrical ; fertile cells not swollen. 



3. H. Hartzii. 

 4. Sterile filaments cylindrical or nioniliform ; fertile cells distinctly 



swollen. 5. 



5. Filaments 30-60 fj. diaru., firm. i. H. penicilliformis. 



5. Filaments 50-170 fj. diam., very soft and lubricous. 



6. H. collabens. 



1. H. PENICILLIFORMIS ( Roth) Fries, 1835, p. 327; Con- 

 ferva Yo-imgana Harvey, 1846-51, PI. CCCXXVIII ; Hormotyi- 

 chion spcciositm Harvey, 1858, p. 90 ; Ulothrix isogona Farlow, 

 1881, p. 45 ; P. B.-A., No. 18. Filaments deep green, attached 

 by outgrowths from within the lower cells, 30-60 p. diam., cells 

 y$-2 diam. long, usually ^-1^2; vegetative cells cylindrical, 

 fertile cells more or less swollen ; chromatophore dense, nearly 

 uniform. Fig. 133. Greenland to N. J. ; Alaska to Cal. 



Erirope. 



A common species of northern regions on both sides of the 

 continent, growing on rocks and timber in exposed places, often 

 in company with Bangia fusco-purpurca, and most abundant in 

 spring and summer. 



2. H. WORMSKJOLDII (Mert.) Fries, 1835, p. 328; Hor- 

 motrichum (?) Wormskjoldii Harvey, 1858, p. 91 ; Urospora 

 Wonnskjoldii Rosenvinge, 1893, p. 920, fig. 36 ; P. B.-A., No. 

 915. Filaments attached by fibrils proceeding from the cell 

 wall, 30-60 /A diam. at the base, increasing in size upward, even 

 to 500 /A ; knver cells cylindrical, 3-10 diam. long, upper cells 

 shorter, fertile cells swollen, the largest nearly globular ; chro- 

 matophore an open network. Greenland ; Alaska to Wash. 



