32 BEITISH DESMIDIACE.E. 



or faintly truncate in the middle ; cell- wall uniformly 

 granulate, granules small and rather variable in dis- 

 position, sometimes irregular, sometimes in more or 

 less distinct longitudinal series, and not infrequently 

 in decussating oblique series. Side view of semicell 

 oblong with a rounded apex. Vertical view subcircular- 

 elliptic. Chloroplasts axile, with one pyrenoid (or 

 two ?) in each semicell. 



Zygospore unknown. 



Length 44-59 p; breadth 18-29 //, ; breadth of 

 isthmus 15-24 ^ ; thickness 21-25'5 p. 



ENGLAND.- -Skip with Common, E. Yorks ! 



IRELAND.- -Dungloe, near Grlenties, Loughs Anna,, 

 Claggan, Magrath and Sproule, Donegal ! Foxford, 

 Mayo ! Clifden and Athry Lough, Galway ! 



Geogr. Distribution.- -Germany. Galicia in Austria. 

 Sweden. Bornholm. Finland. X. Russia. Central 

 China. Xew Zealand (var.). E. Africa. United 

 States. Brazil. 



The distinctions between. C. pseudamoenum and C. amoenum- 

 are very slight. The cell of C. pseudamoenum is proportionately 

 a little narrower, the constriction is less deep., and only one 

 pyrenoid is present in each semicell ; but we are inclined to 

 think the latter character is not constant. 



It is a species which requires thorough investigation. 



Var. basilare Nbrdst, (PI. CII, figs. 10-12.) 



C. pseudamoenum "Wille var. basilare Nordst. in Botan. Notis. 1887, p. 160 ; 

 Freshw. Alg. N. Zeal. 1888, p. 50, t. 5, f. 14; "W. & G. S. West, Some 

 Desm. U. S. 1898, p. 308 ; Borge, Beitrage Alg. Schweden, 1906, p. 29. 



Semicells with a transverse double series of granules 

 across the base just above the isthmus, each pair of 

 granules being part of a bigranulate wart. 



Length 40-53 p ; breadth 22*5-30 p, ; breadth of 

 isthmus 15-22 p, ; thickness 18-19 p. 



SCOTLAND.- -Near Tarbert, Harris, Outer Hebrides ! 



Geogr. Distribution. --Sweden. United States. New 

 Zealand. 



The double series of basal granules are well marked in this 



