THE GREEN ALGAE OF NORTH AMERICA 35 



FRANCEIA L,emmermann, 1898, p. 307. 



Cells single or united in colonies, enclosed in a gelatinous, 

 hyaline envelope ; cell with 2-3 parietal chromatophores, and 

 with long spines, base of spine not thickened ; asexual repro- 

 duction by division of cells in one plane. 



F. OVALIS (France) Lemmermann, 1898, p. 308, Phythelios 

 ovalis France, 1894, p. 2, figs. 1-5; Golenkinia Franzei Chodat, 

 18943, p. 308. Cells ovoid or ellipsoid, 10 /* wide, 17 /u. long, 

 with many spines, about 23 /x long. Fig. 12. Wis., G. M. Smith. 



Europe. 



The dimensions given above are those of the European plant ; 

 Smith's specimens from Wisconsin are decidedly smaller, 

 7 X 13 /*, with spines 15 p. long. 



ACANTHOSPHAERA L,emmermann, 18993, p. 118. 



Cells spherical, solitary (chromatophore single?) with distinct 

 pyrenoid ; membrane very thin, with gelatinous coating and 

 many spines ; spines with lower part rather thick and refring- 

 ent, above very slender and hyaline. Only one species. 



A. ZACHARAISII L,emmermann, 18993, p. 118, PI. I, figs. 

 10-11. Cells 10-14 /A diam., spines 30-35^ long. The princi- 

 pal character of this species is found in the spines, the lower 

 third relatively stout and distinct ; the upper two-thirds delicate 

 and hyaline, visible only when dried, or under high magnifica- 

 tion. Fig. 13. Wis., G. M. Smith. Europe. 



Page 161, for Key to the Species of Nephrocytium, substitute, 



i. Cells semicular with rounded ends. 3. N. obesum. 



i. Cells reniform. 2. 



2. Daughter cells 2-7 /x diam., 3-6 diam. long. i. N. Agardhianum. 



2. Daughter cells 11-22 n diam., 2 diam. long. 2. N. Naegelii. 



and after description of N. NAEGELII, add, 



3. N. OBESUM W. &G. S. West, 1894, p. 13, PI. II, figs. 39- 

 40. Daughter cells nearly semi-circular with rounded ends, the 

 ventral edge straight or slightly concave, 15-28 p wide, rarely 

 more, 25-49 /A long. Two cells within the mother cell wall, 

 which may be over 100 /* long and wide, with very thick mem- 

 brane. Manistique, Mich., Transeau. England, So. America. 



Page 161, for Key to the Species of Tetraedron, substitute, 

 i. Cells without spines or sharp tips to lobes. 2. 



i. Cells with spines or sharp tips to lobes. 8. 



2. Cells with 3 rounded angles. 3. 



2. Cells with more than 3 angles. 4. 



