2(3 BRITISH DESMIDIACE^:. 



Zygospore globose, with a number of prominent 

 mamillse, each mamilla provided with a single short 

 spine. 



Length, without spines, 23-25 [JL ; breadth, without 

 spines, 21-23*3 (JL ; breadth of isthmus 6'6 ^ ; length of 

 spines 5-10 pi; diam. zygosp., without mamillse and 

 spines, 23*5-25 pt ; with mamillae and spines 37-41 p. 



ENGLAND.- -Whernside, W. Yorks ! Keston Common, 

 Kent (with zygospores) ! 



SCOTLAND.- -Not uncommon (Roy & Biss.). Plank- 

 ton of Loch Bairness, Inverness ! 



IRELAND. - -Ballynahinch and Glendalough, Co. Gal- 

 way ! Adrigole, Co. Cork ! 



Geogr. Distribution. Germany. Scandinavia. Para- 

 guay. 



Var. coronulatum Gutw. (PI. CXXXIII, fig. 1.) 



.S7. cuspidatum var. coronulatiun Gutw. Wahr. d. Prioritat, 1890, p. 71 ; 

 Flor. Glon. Okolic Lwowa, 1891, p. 66, t. 3, f. 11 ; Roy & Biss. Scot. 

 Desm. 1894, p. 19. 



Angles of the semicell provided with a circle of tiny 

 verrucse just beneath the point of insertion of the spines. 



Length 26 \L ; breadth, with spines, 36 \i ; breadth of 

 isthmus 5-6 \i . 



SCOTLAND.- -Birsemore Loch, Aberdeen (Roy d Biss.). 



Geogr. Distribution. Galicia in Austria. Norway. 



It is perhaps worth noting that Schroder (' Gallertb. Alg.' 

 1902, p. 168, t. 7, f. 15) figures a circle of secreting pores in 

 exactly the same position as the granules of Gutwinski's 

 .var. coronulatum. Possibly the supposed granules round the 

 angles in this variety are merely the hardened heads of the 

 gelatinous pore-threads, which, in so many Desmids, have fre- 

 quently been mistaken for granules. 



55. Staurastrum pseudocuspidatum Roy & Biss. 



(PL CXXXIII, figs. 2, 3.) 



Staurastrum pseudocuspidatum Roy & Biss. Jap. Desm. 1886, p. 237, t. 2(38, 

 f. 3 ; De Toni, Syll. Alg. 1889, p". 1146 ; West, Alg. N. Wales, 1890, p. 10 ; 

 West & G. S. West. Alg. Madag. 1895, p. 73, t. 8, f. 44. 



