THE GREEN ALGAE OF NORTH AMERICA 97 



2. C. MINOR Klebs, 1896, p. 347, PI. II, figs. i-S ; P. B.-A., 

 No. 1327 ; Tribonema minus Hazen, 1902, p. 185, PI. XXV, 

 figs. 7 and 8. Cells cylindrical or very slightly inflated, 5-6 p 

 diam., 2-4 or even 6 diam. long ; chromatophores 2 or 4 in a cell, 

 arranged in pairs. Mass, to N. J. Europe. 



In habit similar to C. bombycina, and in dimensions not unlike 

 forms of that species, but quite distinct in the symmetrical 

 arrangement of the 2 or 4 chromatophores. 



3. C. UTRICULOSA Kiitzing, Decades, No. 114; Wolle, 1887, 

 p. 140, PI. CXX, figs. 14-16; P. B.-A., Nos. 1071 and 1223; 

 Tribonema utriculosum Hazen, 1902, p. 186, PI. XXV, figs. 9-11. 

 Filaments 11-16 /* diam.; cells usually inflated, but somewhat 

 irregularly, occasionally cylindrical, 1^2-6 diam. long, rarely 

 more ; chromatophores large and often crowded ; cell wall rela- 

 tively thick. Mass, to N. J.; Jamaica. Europe. 



Our largest species, having thicker cell walls and larger 

 chromatophores than the others ; the cells less uniform in size 

 and shape ; the Jamaica plant has cells up to 12 diam. long ; like 

 the other species chiefly a spring plant. 



Many species originally included in Conferva will now be 

 found under other genera ; in some cases, however, the descrip- 

 tions are not sufficiently full to determine the genus. Among 

 the latter are C. sesquipedale Montague, 1859, p. 173, from 

 Louisiana; C. antillarum Kiitzing, 1853, p. 15, PI. XLV, fig. 2, 

 from Trinidad; C. serpens Kiitzing, 1849, p. 372; 1853, p. 15, 

 PI. XlyVI, fig. 2, from Texas ; C. centrifuga Agardh, 1854, p. 

 109, from Nicaragua. 



Family 2. BOTRYDIACEAE. 



Unicellular, multinucleate, with numerous lens- or spindle- 

 shaped chromatophores ; with vesicular part above ground, 

 rhizoidal part below ; asexual reproduction by uniciliate zo- 

 ospores, and by aplanospores. 



Only one genus. 



BOTRYDIUM Wallroth, 1815, p. 153. 



Frond stoutly clavate or globose, with branched lower portion 

 containing protoplasm ; asexual reproduction by uniciliate zo- 

 ospores, formed in large numbers by simultaneous division of the 

 cell contents, escaping by an opening at the summit ; either de- 

 veloping into vegetative plants, or passing into resting spores 

 with thick membrane, which later may develop vegetative plants. 



