New British Freshwater Algse. By W. and G. S. West 153 
after the late Dr. John Roy, who was the first to point out the differ- 
ences between the species of this and those of the allied genus 
Glosterium. 
The var. montana, which we describe of B. obtusa , may perhaps 
he a distinct species. The only other species of the genus is B. 
Pseudoelosterium (Roy) nob. [ Glosterium P seudoclosterium Roy in 
Roy et Biss. Scottish Desm., p. 55.] 
Genus Penium Breb. ; de Bary. 
10. P. didymocarpum Lund. (Desm. Suec., p. 85, t. v. f. 9.) 
In a specimen from a pool between Hawkshead and Yewdale in 
the Lake District (cf. West, Alg. of Eng. Lake Distr., Journ. Roy. 
Micr. Soc., Dec. 1892, p. 721), the outer membrane of the zygospore 
was splitting exactly as figured by Reinsch for ScMzospora minor 
Reinsch (Contrib. Alg. et Fung., tab. xvii. fig. 2). 
11. P. cuticulare sp. n. PL IY. figs. 43, 44. 
P. minutum, cylindricum, diametro 2J-3J-plo longius, ad 
medium non constrictum, apicibus truncatis, angulis leviter 
rotundatis; membrana juveni glabra tenuissima et achroa, 
membrana vetusta firma rufo-ferruginea et minute papilloso- 
punctata. 
Zygosporae angulari-globosae, glabrae. 
Long. 19-34 //, ; lat. 8-10 ya; diam. zygosp. 19-22 y. 
Hab. Thursley Common, Surrey. 
This species differs from P. rufescens Cleve ( = P. rufopellitum 
Roy) in its much smaller size and truncate ends. It differs from 
P. truncatum (Breb.) Ralfs in its membrane and in its less truncate 
ends. 
Genus Micrasterias Ag. 
12. M. denticulata Breb. (Ralfs, Brit. Desm., p. 70, tab. vii. 
%. i). 
Diam. zygosp. sine proc. 116 ya, cum proc. 195 ya. 
PI. III. fig. 29. 
Hob. Halgavor Moor, Cornwall. 
The zygospore in the specimen figured appears to have been 
formed by the conjugation of two individuals which have but just 
separated after division. The figure of M. angulosa Hantzsch, with 
zygospore, given by Roy and Bisset (Scottish Desm., pi. viii. f. 2), 
also appears to have been thus formed. Cf. also remarks under 
Glosterium Ehrenbergii Menegh. 
Genus Euastrum Ehrnb. 
13. E. pectinatum Breb. in Ralfs, Brit. Desm., p. 86, tab. xiv. 
fig. 5. 
Zygospores of this species are more often elliptical or oblong in 
outline than round, as figured by Ralfs. We have noticed this in 
