60 R. Gronblad, New Desmids. 



shown, it is a form of 5. natator West. (Vide Gronbl. 

 Desm. Keur.). 



Mab. Gov. of Archangel. PI. 5 fig. 24—26. 



S. uhtuense, nova sp. Cellulae mediocres, pars media 

 („corpus") quadrata medio incisura parva acuta vix aperta 

 constricta. Semicellulae rectangulares dorso glabro vix re- 

 tuso; angulis superioribus in radios longos in ipso margine 

 denticulatos, in apice bifidos productos; lateribus excavatis, 

 angulis basalibus verrucam utrimque ad isthmum efficientibus, 

 praeterea verrucis 3 utrimque ad isthmum; a vertice visae 

 fusiformes medio crassae. Cum proc. long. 72, lat. 62; sine 

 proc. long. 15, lat. 15, isthm. 8 (i. [N:o 763]. 



This charasteristic species has been observed only once. 

 I know no species with which it could be confused. (Vide 

 5. columbetoides West, Ceylon, pi. 22 f. 8—9). 



Mab. Gov. of Archangel. — PI. 5 fig. 30. 



S. johnsonii West, var. perpendiculatum Gronbl., 

 Desm. Keur. pi. 2 f. 33. Radiis graciliter sursum curvatis. 

 Cum proc. long. 91—99, lat. 110 — 125, isthm. 13//. 

 In the living condition the chloroplasts were easily observed 

 in the vertical view consisting of one pyrenoid in each 

 semicell and 10 radiating plates: two in each process and 

 three on both sides in the median portion. The same 

 system of plates is present in S. natator West var. boldtii 

 Gronbl. and 5. dimazum (Liitk.) Gronbl. The figures 

 will be here reproduced for comparison with each other. 

 [N:o 897 a]. 



Hab. Lempaala (W). PI. 5 fig. 35-35'. 



S. pseudoiotanum, nova sp. Cellulae parvae, medio in- 

 cisura parva obtusa aperta constrictae. Semicellulae bira- 

 diatae e basi subtrapeziformi utrimque in radios longos 

 sensim attenuatos productae; radii in marginibus asymmetrice 

 undulati plane glabri, apice spinulis 3 parvis ornati; a vertice 

 visae fusiformes utrimque polis in radios productis, medio 

 utrimque verrucis singulis parvis depressis bidentatis orna- 

 tae. Long. 27, lat. 30, isthm. 7//. [N:o 886]. 



This species is perhaps nearest to S. tetracerum from 



