1 ( ><> T.IMTlsif DESMIDIACK.K. 



20. Penium cruciferum (De Bary) AYittr. 

 (PL X, figs. 18, ID.) 



Cosmarium ? cruciferum De Bary, Conj. 185$, p. 72, t. 7 G, f. 3-6: Areli. 



in Pi-itch. Infus. 1861, p. 735 ; Eabenh. Flor. Europ. Algai-. Ill, isijs. 



p. 177 ; Lund. Desm. Suec. 1871, p. 51 ; Roy & Biss. Scott. Desm. LS94, 



p. 44. 

 Peniiiin cmriffrv.m (De Bary) "\Vittr. in "\Vittr. & Nordst. Alg. Exsirc. 



]VSL>, No. 482, and in fasc. 21 (1889), p. 48; Nordst. Freshw. Alg. N. 



Zealand, 1888, p. 71, t. 7, f. 19; Nordst. Index Desm. 189(5. p. 90; Wrst 



& G. S. West, Alg. S. England, 1897, p. 479; G. S. West, Alga-ft. 



Cambs. 1899, p. Ill ; West & G. S. West, Alga-fl. Yorks. 1900, p. 47. 

 Dysphinctium cruciferum Hansg. Prodr. Algenfl. Bohm. 1888, p. 185. 



Cells small, about twice longer than their diameter, 

 ellipsoicl-subcylindrical with a slight median constric- 



. ^ 



tion, apices broadly rounded or truncately rounded ; 

 cell-wall smooth and colourless ; chloroplasts with four 

 longitudinal ridges and one central pyrenoid. 



Zygospore unknown. 



Length 15-3-26 ^; breadth 7-6-1 3'5/u. 



ENGLAND. Ogden Clough, Keighley Moor, Eldwick, 

 Baildon Moor, Lindley, Appletreewick, Cocket Moss, 

 Old Cote Moor, and Cray Moss, AY. Yorks ! Market 

 AYeighton, E. Yorks ! Chippenham Fen, Cambridge! 

 Epping Forest, Essex ! AYimbledon Common, Surrey ! 

 Near St. Just, Cornwall ! 



AYALES. Llyn Ogwen and Llyn-cwm-ffynon, Car- 

 narvonshire ! 



SCOTLAND. Near Loch Rosque, Ross ! Lochnagar. 

 Aberdeen; Durris, Kincardine ; Rannoch, Perth! (YA>// 

 A 1 Bissett}. Near Loch Thorn, Renfrew! Loch Dungeon, 

 Kirkcudbright ! 



IKELAND. Loughs Anna, Gatny, and Machugh, 

 Donegal ! Slieve Donard, Down ! 



Gro</)\ Distribution. France. Galicia in Austria. 

 Lapland. New Zealand. East Africa. LTnited States. 

 Cuba. 



This plant was doubtfully placed by its describer under 

 the o-enns Coma iiri nut, but the structure of the chloroplasts 

 and the very slight median constriction indicate a much closer 

 relationship to the genus Penium. Moreover, Wittrock has 

 described a variety of it (var. plnriratliaus} from Sweden in 



