1'LK I'K'OT.KMIM. 1 '.>'. 



1. Pleurotaenium coronatum (Breb.) Uabenli. 

 (IM. XXVII, figs. 10-18; PI. XXVIII, fig. 1,) 



coronatum Ureb. in Ealfs' Brit. De.sm. 1S4S, p. :M7, t. :>.">, f. ii; 

 Aivli. in 1'ritcli. liit'u.s. 18(51, p. 745; Cooke, Kril. Desm. issr,, |.. I::, t. 7, 

 i. L; \\Vst, A1-. N. Wales, IS'. to, p. US].; Roy in Juiiru. But. is; to, 

 p. :;:>"); K'oy \ Biss. Scott. Desm. IS;M., p. I'll. 



Plciirnl ;r//i inn <-iiri>ii<t/ii 111 (Jirrli.) IvU-liuiih. Flor. Europ. Alu,';ir. Ill , ISIjS, 

 p. 11:5 ; Kiirhn. Al^-. Schk-a. 1S?S, p. 1 14; Hans-. Trudr. Algenfl. lJ(.hni. 

 isss, p. 190; Do Toni, Syll. Al-\ 1889, p. 901 ; West, Alg. \V. lrrlan.1, 

 is'.tj, p. us, t, 1 ( J, f. .S-1U ; Nordst. index Do.sin. ISiJU, p. s:; ; West, A1-. 

 En-. Liikf Distr. 1SU2, p. 719; West \ G. S. West, Altf. S. Eii-lainl, 

 IS'.IT, p. -I.SL' ; Al-VL-H. Yorks. litoo, p. .->s ; Al^-. N. Iivhuid, !!)(>-', p. i'ii 



PI. ntiilii/iixtiiH var. curuitut inn (Ureli.j Uoklt ill Bill, till Sv. Vet.-Akad. 

 Ilaudl. Ud. 13, 1S88, no. 6, p. 59. 



Cells largo, 9-12 times longer than their diameter; 

 semicells very slightly and gradually attenuated from 

 base to apex, with a prominent basal inflation and 

 several smaller undulations immediately above it, upper 

 half of lateral margins straight; apices truncate, \villi 

 a peripheral ring of 10-12 large, conical or flattened 

 tubercles (5-6 visible across the apex) ; cell-wall 

 scrobiculate. 



Zygospore unknown. 



Length 430-591 /A; breadth at base of semicells 

 38-70 /A; breadth at apex of semicells 3 7-53 /x. 



Brother's Water and Helvellyn, West- 



moreland ! Pilmoor, N. Yorks ! Thursley Common, 

 Surrey ! Enbridge Lake (//<>//) and New Forest ! , 

 Hants. 



WALES. Capel Curig, Carnarvonshire ! 



SCOTLAND. Inverness ! , Aberdeen, Forfar, Perth ! , 

 Fife (I i "if fy Bissrtt). Sutherland ! Plankton of Loch 

 Ruar and Loch Nan Cuiiine, Sutherland ; and of Loch 

 Fadaghoda, Lewis, Outer Hebrides ! 



IRELAND. Near Lough Magrath, Donegal ! Louglts 

 Aunierin, Derryclare, and Shannacloontippen, Galway ! 

 Dublin and Wicklow (Areiit'r}. 



Geoi/r. Distribution. France. Germany. Galicia 

 in Austria. Norway. Sweden. Central and E. 

 Africa. United States. Brazil. 



