1907] Cushman,— New England Species of Pleurotaenium 105 
21 m; apex 16 j.— Mass.: Tewksbury (Lagerheim). This species 
rests upon this record and could not be verified although many of the 
records of Lagerheim have been gone over by the writer from some 
of the material from which Lagerheim took his desmids. For the 
present it must remain as a single record. 
P. constrictum (Bail.) Wood, F. W. Algae N. Am., 1873, p. 121. 
Docidium constrictum Bail. in Ralfs, Brit. Desm., 1848, p. 218, Pl. 
XXXV, fig. 7. Wolle, Desm. U. S., 1884, p. 50, PI. XI, fig. 2. Cells 
large, 12-15 times as long as wide, very slightly attenuated from base 
to apex; a prominent basal inflation and three or four others in each 
semicell; apices truncate with a peripheral ring, usually 8 large 
bluntly pointed tubercles, membrane evenly punctate; basal inflation 
occasionally with small plications, usually 8 in number. Length 435- 
560 p; breadth at base 40-50 m; apex 25-32 jL.— N. H.: Laconia, 
scarce, (Wests); Pudding Pond, North Conway! Mass.: Tewks- 
bury (Lagerheim). R. I.: Worden’s Pond, North Providence (Bailey). 
P. noposum (Bail) Lund., Nova Acta Reg. Soc. Scient. Upsala, 
ser. 3, Vol. VIII, 1871, p. 90. Docidium nodosum Bailey in Ralfs, 
Brit. Desm., 1848, p. 218, Pl. XXXV, fig. 8. Wolle, Desm. U.S., 
1884, p. 50, Pl. XI, figs. 11-12, Pl. XII, fig. 20. Cells large, 7-10 
times as long as wide, semicells with rings of nodules, usually four 
in number including the basal ring and equidistant, 6-8 nodules in 
each ring; apices dilated, with a ring of 6-8 tubercles. Length 300— 
460 u; breadth at base 40-70 4; apex 28-40 j.— Me.: Orono (Har- 
vey). N. H.: Laconia (Wests); Pudding Pond, North Conway! 
Intervale! Noone's Station! Mass.: Near Salem (Bailey); Lake 
Quinsigamond, Worcester (Stone); Carver's Pond, Bridgewater! 
R. L: Wainskut Pond, North Providence (Bailey). 'Phis seems to 
be one of the commonest species of the genus in New England. It 
is rare in the Dritish Isles. 
P. verrucosum (Bail.) Lund., Nova Acta Reg. Soc. Scient. Upsala, 
ser. 3, Vol. VIII, 1871, p. 6. Closterium verrucosum Bail., Am. Jour. 
Sci., n. s. Vol. I, 1846, p. 127, fig. 4. Docidium verrucosum Bail. in 
Ralfs, Brit. Desm., 1848, p. 218. Wolle, Desm. U. S., 1884, p. 52, 
Pl. X, figs. 4-5. Cells of medium size, about 10- TES long as wide, 
semicells with straight sides, slight inflation at the base, cell wall with 
13-15 rings of irregularly quadrilateral areas, the last ring distally 
more elongated than the others. Length 490-169 4; breadth at base 
30-40 p; apex 22-30 u.— N. H.: Pudding Pond, North Conway, fre- 
quent! Mass.: Mt. Everett (Wolle). R. I.: Near Providence (Bailey). 
