1908] Cushman,— New England Species of Micrasterias. 105 
grows to a very considerable size, its angular form and coarsely punc- 
tate surface giving it a very different appearance from the typical 
form than which it seems to be more rare. 
11. MicnasTERIAS sou (Ehrenb.) Kütz., Spec. Alg., 1849, p. 171; 
W. & G. S. West, Brit. Desm., 1905, p. 95, pl. 46, figs. 1, 2. M. 
radiosa Ralfs, Brit. Desm., 1848, p. 78, pl. 8, fig. 3; Wolle, Desm. 
U. S., 1884, p. 109, pl. 31, fig. 2. ÆEuastrum sol Ehrenb., Mikr. Leb. 
Sud. u. №. Amer., 1843, p. 413, pl. 4, fig. 16. Cells large, circular in 
general outline, very deeply constricted, sinus narrowly open, the sides 
undulate, semicells five lobed, all the sinuses deep; polar lobe with 
nearly parallel sides, broadest distally, apex concave with a slight 
median notch, the outer angles each with two teeth, a single tooth 
within at either side of the median notch; upper lateral lobes larger 
than the lower ones and often with more lobules, lower lobes dichoto- 
mously twice divided to form four equal lobules, the apices variously 
toothed; cell wall unornamented. Length 140-220 м, breadth 125- 
235 м, polar lobe 25-34 м, isthmus 20-25 и. N. H.: Pudding Pond, 
North Conway! Hills Pond, Alton! Mass.: Lake Quinsigamond, 
Worcester (Stone); Reading! Carver’s Pond, Bridgewater: R. I.: 
Near Providence (Bailey). 
lla. MICRASTERIAS SOL, var. ORNATA Nordst., Point sfor. Skand. 
Vaxt., 4, 1880, p. 25; W. &. G. S. West, Brit. Desm., 1905, p. 97, 
pl. 46, figs. 3, 4. М. radiosa, var. ornata Nordst., Desm. Brasil., 
1870, p. 223, pl. 2, fig. 11. M. radiosa Wolle, Desm., U. S., 1884, 
pl.31,fig. 3. М. radiosa var. Wollei Cushman, Notes on Micrasterias, 
1904, p. 394. Cells similar to those of the typical form but with a row 
of minute teeth bordering the sinus and the interlobular incisions except 
on the polar lobe. Length 152 x, breadth 146 x, polar lobe 28 p. 
Mass.: Chilmark, Marthas Vineyard. 
llb. MuicnmasrERIAS SOL, var. Swainii (Hastings) n. comb. М. 
Swainii Hastings, in Wolle, Desm. U. S., 1892, p. 119, pl. 42, fig. 1. 
M. radiosa var. Swainii W. & С. S. West, Some М. A. Desm., 1896, 
р. 240, pl. 13, fig. 30. А variety with the basal lobules of each semicell 
simple and produced into elongated processes. Length 150-160 у, 
breadth 151-164 м, polar lobe 34 y, isthmus 11.5-16 и. №. H.: Roches- 
ter (Hastings). Mass.: Reading (Н. C. по. 644)! і 
12. MicRASTERIAS PAPILLIFERA Bréb., in Ralfs, Brit. Desm., 
1848, p. 72, pl. 9, fig. 1; Wolle, Desm. U. S., 1884, p. 109, pl. 32, 
figs. 8,9; W. & С. S. West, Brit. Desm., 1905, p. 91, pl. 44, figs. 1, 
