THE GREEN ALGAE OF NORTH AMERICA 129 



Snow, 1903, figures three forms found in Lake Erie and de- 

 scribes them all as new species ; they appear to be nearly re- 

 lated to three European species, but sufficiently distinct to give 

 them at least a prima facie right to a place here ; one other 

 form found in America appears identical with a described Euro- 

 pean species; these four, with the arctic "red snow" are all 

 that can safely be given here. As it is more than probable that 

 these are only a small portion of the species occurring here, no 

 key is given. 



1. C. GRACILIS Snow, 1903, p. 374, PI. I, fig. I. Cells 

 cylindrical, rarely ovoid or spherical, 10-13 /* l n g> 5-6 p- diain.; 

 color dull green; cilia 2, about i 1 /? times as long as the cell; 

 stigma a dull red disk, about equidistant from either end ; pyre- 

 noid at extreme posterior end. Lake Erie. 



Nearly related to C. angulosa Dill. 



2. C. COMMUNIS Snow, 1903, p. 374, PI. I, fig. II. Cells 

 ovoid, ellipsoid, or cylindrical, 10-13 P l n g> 6-8 ^ diam.; color 

 light yellowish green ; stigma inconspicuous, near anterior end ; 

 cilia 2, slightly longer than the cell; pyrenoid near center; 

 division longitudinal. Lake Erie. 



Nearly related to S. Steinii Gorosch. 



3. C. GiX)BOSA Snow, 1903, p. 375, Pi. I, fig. III. Cells 

 spherical or slightly ellipsoid, 5-8 ^ diam., cilia 2, slightly longer 

 than the cell ; chromatophore much thickened at posterior end ; 

 stigma small, inconspicuous ; pulsating vacuoles at anterior end ; 

 pyrenoid at posterior end. Lake Erie. 



Nearly related to C. Reinhardi Dang. 



4. C. MUCICOLA Schmidle, 1897, p. 17, PL II, figs. 4-8; 

 Wille, 1903, p. 136, PL IV, fig. 6. Cells ovoid, 6-8 /x long, 3-4^ 

 diam. ; cilia 2, longer than the cell ; pulsating vacuoles at 

 anterior end ; no stigma ; pyrenoid near center of cell ; division 

 transverse. Mass. Europe. 



5. C. NIVAUS (Bauer) Wille, 1903, p. 147, PL III, figs. 

 44 and 45, PL IV, fig. 25. Cell ovoid, 26-36 ; 14-20 /A, wall 

 thickish, uniform or thickened at the posterior end, more or less 

 distinctly lamellate ; chromatophore cup-shaped, with one pyre- 

 floid ; usually thoroughly colored by haematochrome ; asexual 

 reproduction by division into aplanospores with thick, lamellate, 

 smooth wall ; also by Palmella-stage of free, spherical, thick- 

 walled red cells, repeatedly dividing ; sexual reproduction im- 

 perfectly known, but resulting in a spherical or subspherical 

 zygote, 20-34 /" diam., with red contents and colorless wall, the 



