100 Rhodora [JUNE 
sions acute, polar lobe acute at the ends, fusiform, lateral lobes bifid 
at the tips, cell wall minutely punctate. Length 112-150 y, breadth 
112-198 z, polar lobe 110—170 y, isthmus 15-31 и. Me.: Bog between 
Orono and Bangor, frequent (W. West). N. H.: Pudding Pond, 
North Conway, rare! Hill's Pond, Alton (HT. C. no. 664)! Mass.: 
Lake Quinsigamond, Worcester (Stone); Carver's Pond, Bridgewater! 
Lake Watuppa, Fall River (JZ. C. no. 7)! Plymouth (H. C. mo. 
660)! Westport (H. C. no. 702)! Sandwich! Eastham! К. L: 
Near Providence (Bailey); Newport (Leidy); Portsmouth! Nyatt 
(Н. C. no. 673)! This species as will be seen by the above list of 
stations is well distributed. It never seems to be abundant however, 
scattered specimens being the rule in all material examined. 
3. MICRASTERIAS PINNATIFIDA (Kütz.) Ralfs, Brit. Desm., 1848, 
р. 77, pl. 10, fig. 3; Wolle, Desm. U. S., 1884, p. 116, pl. 37, figs. 7, 8; 
Johnson, Species of Micrasterias, 1894, p. 58, pl. 6, figs. 5, 6; W. &. G. 
S. West, Brit. Desm., 1905, p. 80, pl. 41, figs. 7-11, 13. Euastrum 
pinnatifidum Kütz., Phyc. Germ., 1845, p. 134.  Euastrum No. 7, 
Bailey, Amer. Bacill., 1841, pl. 3, fig. 29. Cells small, slightly 
broader than long, deeply constricted, sinus open; semicells three 
lobed, lateral interlobular incisions deep and broadly rounded; polar 
lobe narrower than the cell, but spreading, the apices minutely bifid, 
cell wall minutely punctate. Length 53-65 и, breadth 62-75 y, 
polar lobe 46-55 и, isthmus 9.5-13 u. Me.: Orono (Harvey, W. 
West); Scarboro’ (W. West). N. H.: Intervale! Pudding Pond, 
North Conway! Hill's Pond, Alton (H. C. no. 668)! Mass.: Lake 
Quinsigamond, Worcester (Stone); Medford (H. C. no. 701)! Sessa- 
quin Lake, Middleboro (Н. C. no. 652)! R. L: Wainskut Pond, 
North Providence (Bailey); Nyatt! This small species is more com- 
monly found in numbers than the preceding species, although perhaps 
not any more widely distributed as far as New England is concerned. 
Several varieties have been recorded and described from New Eng- 
land. In abundant material it has been shown that this species in 
common with others of this genus is very variable within certain limits 
(Johnson, Bot. Gaz., 1894). Specimens were found in which one 
semicell was typical, the other being var. inflata Wolle. Var. divisa 
West also occurs in a similar manner. A trigonal form from Orono, 
occurring with the typical form and both var. inflata and var. divisa 
was named var. trigona by West. Such forms which are evidently 
montrosities seem hardly worthy of varietal rank. ‘Thus M. pinnati- 
