4 JBKITISH DESMID1ACEJ3. 



C. Botrytis var. afghanicum Schaarschm. (' Afghan. Alg/ 

 1884,, p. 245, t. 5, f. 19) is not a form of C. Botrytis. 



Var. paxillosporum var. nov. (PI. XCVI, figs. 3, 4.) 



Cell-wall minutely punctate between the granules. 

 Zygospore furnished with short, blunt spines, each of 

 which arises from the apex of a mamillate or bluntly 

 conical projection. 



Length 72-80 p.; breadth 57-61 /u,; thickness 

 29-36 /x; diam. zygosp. without spines 42-5 6 ^, with 

 spines 60-72 /z. 



ENGLAND.- -Yorkshire ! Surrey (zygospores from 

 Frensham Great Pond, and from pond east of Chapel 

 Wood) ! Cornwall ! 



SCOTLAND.- -Sutherland ! Near Kirkwall, Orkneys! 



The vegetative cells of tliis variety differ only in the 

 presence of distinct punctulations between the granules, but 

 the zygospore differs markedly from that of typical C, Botrytis 

 in the blunt spines which arise from conspicuously swollen 

 bases. The spines of the mature zygospores remain bluntly 

 rounded with no trace of apical denticulations. 



Var. subtumidum Wittr. (PI. XCVII, fig. 1.) 



C. Botrytis var. subtumidum Wittr. Gotl. 6l. sotv. Alg. 1872, p. 57, t. 4, 

 f. 12; Boldt, Desm. Gronland, 1888, p. 28; Andersson, Sverig. Chlor. 

 1890, p. 14 ; Schmidle, Chlorophy.-Fl. Torfstiche Virnheim, 1894, p. 58 ; 

 Koy & Biss. Scott. Desm. 1894, p. 44 ; Borge, Beitriige Alg. Schweden, 

 1906, p. 30. 



Cells rather wider than in the type, basal angles 

 more projecting, slightly tumid in the centre of the 

 semicells, and with the granules covering the tumour 

 somewhat larger than the rest of the granules. 



Length 52-80 p. ; breadth 43-65 p, ; breadth of 

 isthmus 10-15/x; thickness 28-38*4 p. 



SCOTLAND. Aberdeen, Kincardine, Perth (Hoy Sf 

 Bis sett). 



Geogr. Distribution. Germany. Galicia in Austria. 

 Sweden. N. Russia. Greenland. Siberia. 



This variety must be exceedingly rare,, and we have never 

 seen any form of C. Botrytis that we could with justice refer 

 to it. 



