Algse of the English Lake District. By Wm. West. 719 
Genus Gymnozyga Ehrnb. 
G. moniliformis Ehrnb. Hp., W., Sk., C., Hk. 
Genus Desmidium Ag. 
D. cylindrieum Grev. L. 
D. Swartzii Ag. W., B., R., Hk., Deepdale, H. (at 2400 ft.). 
D. aptogonum Breb. L., S. 
var. acutius Nordst. Bn. 
Genus Pleurotsenium Nag. 
P. coronatum (Breb.) Rabh. B. 
var. nodulosum (Breb.) West. [ Docidium coronatum 
Breb. var. nodulosum (Breb.) Roy]. Bo. 
P. Ehrenbergii (Ralfs.) De Bary. Frequent. 
P. clavatum (Kiitz.) De Bary. B. 
P. maximum (Reinsch) Lund. 
var. Occident ale var. n. [P. maximum West (Contrib. 
Ereshw. Alg. of W. Ireland, p. 119)]. 
Var. ad formam typicam similis sed ter minor est. W., 
Bn., Hk. 
This is 2J to 3J times smaller, but in form it agrees exactly with 
the species described by Reinsch (Alg. FI. yon Mitt. Frank., p. 184, 
t. 12, f. iv.). It is quite distinct from P. Ehrenbergii (Ralfs) De 
Bary. 
P. truncatum (Breb.) Nag. Bo. 
Genus Closterium Nitzsch. 
G. didymotocum Corda. C., Hk. 
C . abruptum sp. n. Fig. 1. 
Cl. anguste lanceolatum, circiter decies longius quam 
latius, leve curvatum, latere ventrali non (vel levissime) 
tumidum, sensim aequaliter attenuatum utrimque in apicem 
truncatum ; membrana luteola et non-striata ; pyrenoidibus 
8-10 in unica serie. 
Long. 127-156 /jl; lat. ad medium 12-15*5 lat. apic. 
6-7 ya. C., Hk., Esth waite Water, Ennerdale. 
This is similar in shape to some forms of Cl. intermedium Ralfs, 
but differs in its much smaller size and in its membrane not being 
striolated. 
forma punctata. 
Forma membrana irregulariter punctata. C. 
G. obtusum Breb. 
Forma apicibus subtruncatis. 
Long. 41 yu ; lat. 7*5 ya. Fig. 13. H. 
C. lunula (Muller) Nitzsch. Frequent. 
