1907] Cushman,— New England Species of Penium 229 
North Woodstock, common! Mass.: Medford! Bridgewater! East 
Bridgewater! Lake Watuppa, Fall River! 
PENIUM LIBELLULA, var. INTERRUPTUM (West) W. & G. S. West. 
Penium closterioides, forma interrupta West, Journ. Roy. Micr. 
Soc., 1892, p. 721. 
Penium Libellula, var. interruptum W. &. G. S. West, Journ. Roy. 
Micr. Soc., 1897, p. 479; Brit. Desm., vol. 1, 1904, p. 74, pl. 7, figs. 9, 10. 
Smaller than the typical form, the chloroplasts divided three times 
transversely, therefore in each cell four chloroplasts each containing 
à pyrenoid. 
Length 120-170 x; breadth 22-37 p. 
N. H.: Pudding Pond, North Conway! Mass.: Pondville! Plain- 
ville! 
PENIUM LIBELLULA, var. INTERMEDIUM Roy & Biss. 
Penium Libellula, var. intermedium Roy & Biss., Ann. Scot. Nat. 
Hist., No. 12, Oct. 1894, p. 252; W. & G. S. West, Brit. Desm., 
vol. 1, 1904, p. 74, pl. 7, fig. 11. 
Differs from the typical form in size, being about one half the size, 
otherwise typical. 
Length 124 u; breadth 22 y. 
Mass.: Pondville! 
PENIUM Navicuta Bréb. 
Penium Navicula Bréb., Mem. d. l. soc. imp. sc. nat. Cherbourg, 
vol. 4, 1856, p. 146, pl. 2, fig. 37; Wolle, Desm. U. S., 1884, p. 36, 
pl. 5, fig. 16; W. & G. S. West, Brit. Desm., vol. 1, 1904, p. 75, pl. 7, 
fig. 12-15, 19. 
Cells small, 34—44 times as long as wide, fusiform, no constriction, 
ends broadly rounded, vacuoles with two or three moving granules. 
Length 55-60 4; breadth 14 p. 
Me.: Orono (W. West); Mass.: Plainville! Lake Watuppa, 
Fall River! 
PENIUM MARGARITACEUM (Ehrenb.) Bréb. 
Closterium | margaritaceum Ehrenb., Die Infusionthierchen als 
volkommene Organismen, 1838, p. 95, pl. 6, fig. XIII. 
