131 



ENGLAND. Cumberland! Westmoreland (at 2, -1-nn |'i. 

 on Helvellyn) ! W., N., and E. Yorks (/ygosp. From 

 Markington, \\ r . Yorks)! Lancashire! Cheshire 

 (7iV//*). Lincolnshire! Suffolk! Essex! Cambridge! 

 \Var\\-ick (!!'///*). Surrey! Sussex (/.W/x). Hants! 

 (Bennett). Devon! (JJenncft). Cornwall! (Rolfs). 



WALKS. Fairly general in the north ! 



SCOTLAND. General ! Zygospores from Coul in 

 Ross ; between. Loch Kinnord and Cambus O'May, 

 A 1 lerdeen ; Loch Lnnclie, Perth ( Uoij ^ Hixxett) . General 

 in the Outer Hebrides ! Orkneys ! Shetlands ! 



IRKLAXD. Mayo ! Galwav ! Kerry ! Donegal ! 



/ / e/ O 



Dublin and Wicklow (Archer). Antrim! Down! 



6rW//-. Distribution. France. Germany. Austria. 

 Galicia. Hungary. Italy. Portugal. Norway. Sweden. 

 Denmark. Bornholm. Finland. N., S., and Central 

 Russia. Faeroes. Iceland. Nova Zembla. Spitx- 

 bergen. Greenland. Siberia. Central China. Japan. 

 Ceylon. Siam. Java. Australia. New Zealand. 

 Central and E. Africa. United States. "W. Indies. 

 Brazil. Uruguay. 



Some forms of this species have been noticed in which the 

 cell-wall was finely punctate, and others in which it \vas dis- 

 tinctly granulate. The granules were large, but only of 

 slight elevation. 



Yar. arcuatum (Breb.) Rabenh. (PI. XV, figs. 21, 22.) 



Clostcrium arcuatum Breb. in Ralfs' Brit. Dosm. 1848, p. 219 ; Bn'b. 



Liste Desm. 1856, p. 14-9, t. 2, f. 38 ; Lund. Desin. Suec. 1871, p. SO ; 



Eoy & Biss. Scott. Desm. 1894, p. 24-3 ; Nortlst. Index Desm. ISiiii, p. 50; 



West & G. S. West, Alga-fl. Yorks. 1900, p. 49. 

 Cl. Dianx var. arcuatum Eabenh. Flor. Europ. Alp;-. Ill, 1868, p. 133 ; 



Hunsg. Prodr. Alo-cnfl. Bohm. 1888, p. 181 ; Gntw. Flor. Glon. Okolic 



Tarnopola, 1894, p. 80; Nortlst. Index Desm. 189(5, p. In:,. 



About 10 times longer than the diameter, slightly 

 smaller and more strongly curved than the typical form, 

 outer margin 140 152 of arc; cell-wall of a pale 

 yellow colour. 



Distance between apices 129 290 /A; breadth 18-2-^/^: 

 breadth of apices 0-7 ^ ; diam zygosp. 27-29 p. 



