56 R. Gronblad, New Desmids. 



is easily distinguished from A octocornis by its size, which 

 is twice as large, the submamillate angles and the very 

 different sinus. Also X. smithii var. majus (R a 1 f s) West 

 is smaller with shorter and normally paired spines, with a 

 thickened central area and a different shape of its semicells. 

 Hab. Gov. of Archangel. PI. 3 fig. 58—60. 



Genus Staurastrum Meyen. 



S. pachyrhynchum Nordst. var. uhtuense nova var. 

 Cellulae a fronte visae dorso altius convexo, membrana 

 etiam in apice incrassata; a vertice visae triangulae lateri- 

 bus subrectis (vix conspicue retusis), angulis plus obtusis. 

 Massa chlorophyllacea axilis nucleis singulis. Membrana 

 subtilissime porosa. Long. 35, lat. 30, isthm. 11 /(. [N:o 842]. 



Hab. Gov. of Archangel. PI. 3 fig. 44—45. 



S. minutissimum Rein sen. var. convexum West, 

 Mngr. IV p. 131 pi. 119 f. 3 (syn. = S. minutissimum 

 Rein sen., Spec. gen. alg. nov. pi. 23 A II fig. 1 — 2); 

 Boldt, Desm. Gronl. pi, II f. 41. — The Finnish specimens 

 have in vertical view less retuse sides. Long. 14,5 — 11,9 

 -13,2—13,2, lat. 14,5—13,9—14,5, 13,9, isthm. 11—11,9—11,1— 

 ll,i fA. [N:o 1091]. 



Hab. Nadendal (SW), leg. Elfv. PI. 3 fig. 41—43. 



S. tristichum Elfv. This species seems to be exceedingly 

 rare, not being recorded since it was described for the 

 first time (Cfr. Nordst., Index & Suppl.). Our drawings 

 are made from a specimen in a sample from Prof. Elf- 

 v i n g's collection. In the front view the sinus is deeper 

 and also more rounded (not acute) than according to 

 Elfving's figure. Nevertheless I think this is nothing but 

 the typical S. tristichum. It is closely allied to „S. pygmaeum 

 Breb. forma 4-gona" Boldt (Desm. Gronl. pi. 2 f. 42). 

 Compare also 5. pygmaeum v. subglabrum Boldt (Sibir. 

 Chlor. pi. 5 f. 20); S. pygm. v. subglabr. forma Eichler 



