200 BRITISH DESMIDIACE^:. 



WALES. General in Carnarvonshire! Dolgelly, 

 Merioneth (Ralfs). 



SCOTLAND.- -General ! (Roy fy Bissett). Common in 

 the Outer Hebrides ! Orkneys ! Shetlands ! 



IRELAND. Donegal ! Mayo ! Galway ! Kerry ! 

 Dublin and Wicklow (Archer). Down ! 



Geogr. Distribution. France. Germany. Austria 

 and Galicia. Hungary. Italy. Norway. Sweden. 

 Denmark. Bornholm. Finland. S. Russia. India. 

 Ceylon. Burmah (form). "W. Africa. Azores. 

 United States. Brazil. Paraguay. Uruguay (form). 

 Argentina. Patagonia (form). 



C. pyramidatum is generally distributed in the peat-bogs 

 and peaty pools of the British Islands. It is also abundant 

 in the rocky pools and lakes of the western areas of Scotland 

 and Ireland. 



Ralfs states that he obtained the zygospores at Dolgelly in 

 Wales, but they do not appear to have been observed since. 

 It is quite possible that the zygospores Ralfs examined were 

 those of C. pseudopyramidatum, as that species was included 

 in his C. pyramidatum. Moreover, he describes them as 

 " tuberculated/' which is a conspicuous feature of the zygo- 

 spores of C. pseudopyramidatum. 



The largest form of the species (forma tropica West & G. 

 S. West) is known from Angola, W. Africa. It reaches a 

 length of 170 /^ and a breadth of 90 /<, and the semicells are 

 slightly inflated with less truncate apices. 



Var. angustatum West & G. S. West. (PI. LXIV, 



fig. 8.) 



C. pyramidatum Breb. var. anyustatum West & G. S. West, New Brit. 

 Freshw. Alg. 1894, p. 5, t. 1, f. 18. 



Cells narrower than in the type, almost twice as 

 long as broad ; semicells more evidently pyramidate, 

 with straighter sides, basal angles very little rounded 

 and almost submamillate. 



Length 90-92 p ; breadth 48-50 p. ; breadth of isth- 

 mus 13 '5-1 5 p. 



ENGLAND. --Near Bowness, Westmoreland ! 



IRELAND. Castletown, Kerry ! 



* / 



