COSMAFJUM. 191 



1 : 1'3. Cell-wall smooth. Chloroplasts axile, with 

 one pyrenoid. 



Zygospore unknown. 



Length 23-39/i; breadth 14-22/1,; breadth of apex 

 7-11 p.; breadth of isthmus 6'5-ll ft; thickness 9-17 p.. 



EXCILAXD.- -Helln Pot near Selside, Mougiiton Fell, 

 Penyghent, S. of Cray Moss, and Cowgill Wold Moss, 

 AY. Yorks ! Ytickle Fell and Mossdale Moor, TYiddale 

 Fell, X. Yorks ! Chippenham Fen, Cambridgeshire ! 

 Enbridge Lake, Hants (Roy). 



SCOTLAND.- -Inverness, Aberdeen, Kincardine, Forfar, 

 Perth, Stirling (Roy $ Bissetf). 



IRELAND.- -Cloonee Lough, Kerry! Dublin and 

 TVicklow (Archer). Slieve Donard, Down ! 



Geor/r. Distribution. Germany. Galicia and Bohemia 

 in Austria. Italy. Sweden. Greenland. Spitzbergen. 

 Xova Zembla. Java (form). United States. 



This minute species is principally subalpine in habitat, 

 being frequently found among mosses on wet limestone rocks, 

 and its occurrence in the fen district of Cambridgeshire is 

 certainly remarkable. 



AVe have explained at length the reasons for regarding 

 Cosmarium augustatum (Wittr.) Nordst. as synonymous with 

 Euastrum PoTcornyanum Grim, in the c Journal of Botany/ 

 1900, p. 292-293, and in the < Alga-fl. Yorks/ 1900, p. 79. 



C. Pokornyanum should be compared with C. trilobulatum, 

 from which it is distinguished by its retuse lobes and by the 

 tumid vertical view. 



42. Cosmarium pseudatlanthoideum West. 

 (PL LXIII, figs. 16, 17.) 



Cosmarium pseudatlanthoideum West, Alg. Eng. Lake Distr. 1892, p. 725, 

 t. 9, f. 21 ; Schmidle, in Hedwigia, 1895, p. 8-4. 



Cells very small, about 1^- times longer than broad, 

 deeply constricted, sinus very narrow, slightly open 

 outwards ; semicells subtriangular from a broad base, 

 basal angles broadly rounded, lower half of sides con- 

 yex, upper half concave, apex narrow and rounded. 

 Side view of semicell elliptic-ovate. Vertical view 



