108 BRITISH HKSMIDIACE^I. 



Cl. (/ntrile is a widely distributed species and is often abun- 

 dant in collections from permanent bog's. It is undoubtedly 

 nearest to Cl. Cornu Elirenb.. from which it is distinguished 



' O 



by its proportionately greater length, by the straighter 

 nu'dian part of the cell, by tlie incurved and narrower apices, 

 and by the form of the zygospore. 



The curvature of Cl. gracile is very similar to that of ('/. 

 juncidum, but in no other respect do these species resemble 

 each other. They are in no way closely related. 



The figures given by Brebisscm and by Cooke are very poor 

 representations of the species, and have led to considerable 

 confusion. 



The zygospores of this species are somewhat variable. 

 They are seldom spherical, but are more often angular-globose 

 or even subquadrate with rounded angles. 



Var. elongatum var. non. (PI. XXI, figs. 14-10.) 



Cells very elongate, 85-95 times longer than their 

 diameter, apices obtusely rounded. 

 Length 270-300 /x; breadth 3-4 /u,. 

 SCOTLAND. Rhiconich, Sutherland ! 

 It; ELAND. Cromagloun, Kerry ! Clough, Antrim ! 



Var. tenue (Lemm.) West & G. S. West. (PI. XXI, 



fig. 13.) 



Cl. limneticum Lemm. var. tenue Lemm. Phytoplankton silchsis. Teichc, 



is<i!, p. 2S, t. 2, f. 42-44. 

 Cl. (jracilc var. tcnuc (Lemm.) West & G. S. West, Frcsliw. Alg. Ceylon, 



1902, p. 138, t. 18, f. 22, 23 ; Alg. N. Ireland, 1902, p. 25. 



Cells smaller and somewhat thinner than in the 

 typical form. 



Length 09-110 p ; breadth 2'5-3-r. p. 



Scotland. Near Tarbert, Harris, and Balnllan, 

 Lewis, Outer Hebrides ! W. of Kirkwall, Orkneys! 



Iri'hiiiiL Dungloe, Loughs Anna and Sproule, and 

 near Though Magrath, Donegal ! Slieve Donard, DOAVII ! 



(Icoi/r. Distribution. (iermany. Ceylon. 



This variety is sometimes very abundant amongst Splint/inim 

 cuspidatum, intermingled with Netriuin, Dit/itii* and Staur- 

 (iKfntiii brachiatum. We have previously commented upon 

 the erroneous measurements given by Lemmermann. 



