182 



Chlorophycece 



in any British specimens. Each cell possesses at its upper pole a 

 small conical projection which forms a basal sheath for a long, 



delicate seta or bristle. This 

 bristle is extremely fine and 

 fragile, and is commonly broken 

 off at the apex of the basal 

 sheath. In most specimens it is 

 impossible to see any sheath-like 

 structure in the conical projec- 

 tion, the bristle appearing to 

 arise from its apex. The chloro- 

 plast is very variable, but in 

 some specimens it is distinctly 

 parietal with one pyrenoid. The 

 division of the cells sometimes 

 takes place by the formation of 

 a horizontal division-plane, the 

 lower daughter-cell migrating 

 to the side. Asexual reproduc- 

 tion occurs by zoogonidia, pro- 

 duced four (or more ?) in a cell. 

 There is some little confusion 

 described by Borzi in 1892 



Fig. 70. A and B, Chcetospharidium 

 globosum (Nordst.) Klebahn; A, from 

 Esher Common, Surrey; B, from Bow- 

 ness, Westmoreland. C, Ch. globosum 

 var. depressum (West & G. S. West), 

 from the New Forest, Hants. (All 

 x 370.) 



between this genus and one 



in ly2 as 



Nordstedtia 1 . The latter was supposed to be founded on a plant 

 described by Nordstedt as Herposteiron globosa*, and since referred 

 by Wolle to the genus 'Aphanochcete.' Klebahn, who compared 

 the original specimens of Nordstedt with Borzi's drawings of 

 Nordstedtia, affirmed that the latter represented an entirely 

 different plant. This being the case, one is compelled to accept 

 the genus Chcetosphceridium for the plants described by Nordstedt 

 as " Herposteiron globosa." 



Ch. globosum (Nordst.) Klebahn is widely distributed in the British 

 Islands, occurring chiefly in the Sphagnum-pools of permanent bogs. The 

 cells are 11 18 p, in diameter, loosely associated, and occasionally surrounded 

 by a gelatinous envelope (fig. 70 A and B). There is a curious var. depressum 

 of this species with the cells much depressed (fig. 70 C). 



The plant described as Chcetosphceridium Pringsheimii by Klebahn appears 

 to be identical with Aphanochcete globosa var. minor Hansgirg, and if it is 

 distinct from Ch. globosum it should be known as Ch. minus Hansg. Most 



1 Borzi in Nuova Notarisia, iii, 1892, p. 50. 



2 Nordstedt, Alg. aq. dulc. et Char. Sandvic. 1878, p. 23, t. ii, f. 22, 23. 



