7S r-IMTlSH DESMIDIACE.E. 



Iliissj;!. Spit/beru'en. Greenland. Siberia, United States. 



Ar_M'iit inc. 



.s 1 /. sfi.nni'iox'im is a beautiful species, and is very well charac- 

 t.-ri-i'.l l>y its |)rominent and regularly arranged verrucae, which 

 are <> l.-ir^e as almost to constitute short processes with emar- 

 LMiiat.- apices. The front view naturally varies in appearance 

 according as the individual is observed from the face view or 

 tin 1 anide. 



Var. perbifidum West. (PI. CXL, fig. 16.) 



St. spongiosum var. perbifidum West, Alg. W. Ireland, 1892, p. 175, t. 23, 

 f \\ Uitk. Desin. Attersees, 1893, p. 365, t. 9, f. 15; Schmidle, Beitr. 

 Alp. Alir. is!r,, p. 32 ; W. & G. S. West, Alg. S. England, 1897, p. 494 ; 

 li.ir-j. Alg. Faeroes, 1901, p. 234; Borge, Botan. Notiser, 1913, p. 50. 



This variety differs from the type in that the granules 

 <t the emarginate processes are developed into stout 

 spines. 



I )imensions as in the type. 



lv\( : LAND.- -Borrowdale, Cumberland ! Thursley Com- 

 mon. Surrey (3- and 4-ended forms) ! 



I I:K LAND.- -Near Westport, Co. Mayo ! 



('<'n<j ,- . Distribution. Germany. Austria. Sweden. 

 Faeroes. 



Transitional forms between this variety and the type form are 

 frequent. 



Var. Griffithsianum (Nag.) Lagerh. (PL CXL, fig. 15.) 



/'/////'/.*/////// (/W///./f7////>////) Criffithsianum Xag. Gatt. einz. Al. 1849, 

 p. I2S, t. S. ('. f. L>. 



Staurastrum Uriflithximnuii Aivh. in Quart. Journ. Micr. Sci. 1866, p. 67; 

 Cookr. Brit. Dcsm. 1887, p. 154, t. 53, f. 2; Georgev. Desm. Wlasina 



L909 p. 203. 



x/. spongiosum var. ^'/-///f///.</V/ ///// Lagerh. in Wittr. & Nordst, Alg. exs 

 1886 : DC Tmii, Syll. Alg. 1889, p. 1174 ; Liitkem. Desm. Atter- 

 .'.'{. p. ~n4 ; Borge, Botan. Notiser, 1913, p. 50. 



'11s with the sinus open towards the exterior, sides 



in the end view nearly straight or slightly concave, with 



deep mimded and prominent concavity between the 



two MHMlmii processes of each lateral margin ; in other 



characters similar to the type. In the development of 



spines this variety resembles var. perbifidum West. 



