1908] Cushman,— New England Species of Micrasterias. 111 
three wide portions, connected by narrowed sections, the interlobular 
incisions deep but broadly rounded, sinus deep, acute angled, median 
and apical lobes split laterally, basal one split into three parts, the 
middle one of the three longest and occasionally bifid, apices of all 
the lobes minutely toothed, cell wall punctate. Length 160—195 p, 
breadth 120-155 м, polar lobe 120-140 y, isthmus 21-31 s. Me.: 
Spencer Pond, East Middlesex (H. C. no. 633)! N. H.: Pudding 
Pond, North Conway. Rare! Mass.: Lake Quinsigamond, Worces- 
ter (Stone); Tewksbury (Lagerheim); Carvers Pond, Bridgewater! 
Westport (Н. С. по. 689)! R.I.: near Providence (Bailey). 
21a. MicRAsTERIAS MURICATA, forma MINOR Cushman, Desm. 
Flora N. H., 1905, p. 254. A form in which the cells are much smaller 
than in the typical form of the species. Length 123 и, breadth 84 y, 
polar lobe 84 и, isthmus 16 и. N. H.: Intervale! 
22. MICRASTERIAS FOLIACEA Bailey, in Ralfs. Brit. Desm., 1848, 
р. 210, pl. 35, fig. 3; Wolle, Desm. U. S., 1884, p. 118, pl. 38, figs. 10, 
11; Johnson, Bot. Gaz., 1894, p. 56, pl. 6, figs. 1-4. Cells small, sub- 
quadrate in outline, deeply constricted, sinus narrow, linear throughout 
its length, semicell five lobed, lateral lobes with their outer margins 
nearly straight, the two sides of the semicell parallel, the upper of the 
lateral lobes being elongated and somewhat curved, each lateral lobe 
divided into two or four lobules, the upper usually with the distal 
lobule shortest; polar lobe rhomboid, end with a quadrate incision with 
a broad plate like projection on either side, between which are two 
teeth at one side and two on the reverse side, the opposite polar lobe 
exactly reversed, the shape allowing the interlocking of the cells to form 
long linear series: surface typically smooth. Length 80-96 y, breadth 
80-85 y, polar lobe 36-38 y, isthmus 14-15 м, №. H.: Laconia, scarce 
(H. J. no. 665) Pudding Pond, North Conway, rare! Mass.: Gilder 
Pond, Mt. Everett, Mount Washington (Wolle); Lake Quinsigamond, 
Worcester, (Stone). R. I.: Worden's Pond, near Providence (Bailey). 
Johnson worked out the structure of the polar lobe in this species and 
his figures give a better idea of the structure than a description. ‘This 
is one of our most beautiful and most interesting species. Johnson 
records filaments with over a hundred cells. 
92a. MICRASTERIAS FOLIACEA, var. granulifera n. var. Like the 
type but the surface covered with large irregularly disposed granules. 
Var. membrana granulis magnis inordinatim dispositis. N. H.: Pud- 
ding Pond, North Conway! 
Boston SOCIETY or NATURAL HISTORY. 
