62 R. Gronblad, New Desmids. 



radios productis, angulis utrimque verruca parva instructis. 

 Long. 24, lat. 22, crass. 6,6, isthm. 4 //. [N:o 1084]. — In 

 the front view this variety very much resembles 5. iotanum 

 v. tortum Teiling, Schwed. Plankt. II p. 65 fig. 15 (on 

 page 64) which is neither figured nor described in vertical 

 view (likewise the dimensions are not given, but, according 

 to the figure, they should be: cum proc. long. 24, lat. 24, 

 isthm. c. 4 (jl). It does not seem to me correct that the 

 „var. tortum" is referred to 5. iotanum Wo lie- West, from 

 which it differs by the rounded basal angles (comp. the 

 diagnosis by West: „non rotundatis") with 3-denticulate 

 processes at the apex (by West „emarginatis"). Moreover 

 Tei ling's variety is biradiate, whilst the type is triradiate. 

 The distinctive feature of Teiling's variety „circa 40 

 tortae" is of no systematic value, the small biradiate (but 

 also] 3-radiate) Staurastra very often being twisted at the 

 isthmus. (Vide West, Mngr. IV page 172 „The alternation 



is of no specific importance — "). The „var. tortum" 



is probably a form of S. tetracerum according to Dr 

 B o r g e. 



Hab. (SW?), leg. Elfv. PL 5 fig. 31-32. 



(?) var. subexcavatum, nova var. Semicellulae parte 

 basali multo minore, radiis longioribus marginibus denticu- 

 latis, apicibus 3-dentatis; dorso leviter excavato; a vertice 

 visum fusiforme. Cum proc. long. 38, lat. 63, crass. 8 it. 

 [N:o 857]. — I am not sure whether this variety is correctly 

 placed under 5. tetracerum. Compare also S. subparvulum 

 West, Ceylon pi. 22 f. 7; 5. excavatum West, Madagasc. 

 pi. 8 f. 42 and „forma" West, Yan Yean pi. 6 f. 19. 



Hub. Plankton from Vuoksen (SE), leg. K. M. Levan- 

 der. — PI. 5 fig. 28—29. 



S. dimazum (Liitkem.) Gronbl. Note the chloro- 

 plasts! Lat. 85//, crass. 23//. [N:o 1225]. 



hab. Esbo (S), leg. C. Cz. PI. 5 fig. 45. 



S. natator West var. boldtii Gronbl. Note the chloro- 

 plasts! Lat. 76//, crass. 23//. [N:o 1224]. 



Hab. Esbo (S), leg. C. Cz. PI. 5 fig. 46. 



