102 Rhodora [JUNE 
6. MiCRASTERIAS TRUNCATA (Corda) Bréb., in Ralfs, Brit. Desm., 
1848, p. 75, pl. 8, fig. 4, pl. 10, fig. 5; Wood, Fr. Alg., 1873, p. 144, pl. 
21, fig. 15; Wolle, Desm. U. S., 1884, p. 114, pl. 38, fig. 6; W. & G. 
S. West, Brit. Desm., 1905, p. 82, pl. 42, figs. 1-8, pl. 45, figs. 5, 6. 
Cosmarium truncatum Corda, Alm. de Carlsbad, 1834, pp. 180, 
206, pl. 2, figs. 23, 24. М. crenata Bréb., in Ralfs, Brit. Desm., 
1848, p. 75, pl. 7, fig. 2, pl. 10, fig. 4; W. & G. S. West, Brit. Desm., 
1905, p. 85, pl. 42, figs. 10-13.  Euastrum No. 3 Bailey, Amer. Bacill., 
1841, p. 294, pl. 3, fig. 24. Cells small, very slightly longer than 
broad, medium sinus deep and narrow, polar lobe wide, in general 
fusiform, lateral angles acuminate or bifid, end of the lobe either broadly 
rounded or slightly retuse; lateral lobes two on each side separated 
from the polar lobe by a comparatively deep sinus, slightly open; sinus 
between the lateral lobes shallow and narrowly open, ultimate lobules 
variable, usually each lobe with two lobules which may have two 
projections or none. Length 86-113 /, breadth 80-110 y, polar lobe 
55-81 м, isthmus 14-22 и. Me.: Orono (Harvey, W. West); Spen- 
cer Pond, East Middlesex (H. C. no. 629)! Mud Pond, Township 
Range! Kittery! Bridgton! N. H.: Hanover (Edwards); Inter- 
vale! Pudding Pond, North Conway! North Woodstock! Mass.: 
Amherst (W. West); Lake Quinsigamond, Worcester (Stone) ; 
Tewksbury (Lagerheim); Reading! Lake Watuppa, Fall River (H. 
C. no. 38)! Sandwich! Eastham! Chilmark! Squam Pond, Nan- 
tucket! R. I.: Wainskut Pond, North Providence (Bailey). Ав 
various gradations occur between typical M. truncata and the form 
known as M. crenata Bréb., it seems best not to use the two names. 
Especially is this true when in American specimens one finds what 
would pass for typical M. crenata making up one semicell and the 
other having the retuse polar lobe and the lateral lobes of typical M. 
truncata. Since noting such specimens it has seemed best to place all 
the forms under M. truncata. For purposes of distinguishing between 
the two extremes, the form with the deeper and more rounded polar 
lobe and the less deeply incised lateral lobes may be known as M. 
truncata (Corda) Bréb., var. crenata (Bréb). 
7. MICRASTERIAS JENNERI Ralfs, Brit Desm., 1848, p. 76, pl. 11, 
fig. 1; Wood, Fr. Alg., 1873, p. 146, pl. 13, fig. 7; W. & G. S. West, 
Brit. Desm., 1905, p. 86, pl. 42, fig. 14, pl. 43, figs. 1, 2. Me.: Orono 
(Harvey), “with truncata." This is the only New England record 
for this species. It is worthy of note that W. West does not record it 
from his material from the same locality. 
