Genus Closterium Nitzsch. 



CI. tumidum Johnson; West Mngr. I pi. 19 f. 15—18; 

 var. nylandicum, nova var. Cellulae longiores apicibus plus 

 attenuatis subtruncatis, saepe irregulariter curvatae. Locum 

 medium inter C. tumidum et C. cornu tenens. Zygospora 

 subrectangularis (saepe obliqua) lateribus longitudinalibus 

 subrectis, lateribus transversalibus excavatis, angulis valde 

 rotundatis non productis; a latere visa ovalis. Long. 100—200, 

 lat. 8—11; zygospora long. 30—34, lat. 17—19//. [N:o 1129] J ) 



This variety differs considerably from the typical C. tu- 

 midum in being much longer and slenderer with more 

 elongated and attenuated apices. It is distinguished from 

 C. cornu by its thicker median portion. The zygospore is 

 much rounded at the angles, which are never produced. 

 The copulating cells are always parallel and quite close to 

 each other. Another allied species seems to be C. acutum 

 Breb. (vide Printz, Beitr. Norweg. pi. 1 f. 5.) 



Hab. Bjorko in Esbo (S). PI. 5 fig. 38—41. 



CI. pseudolunula Borge, N.-Amer. pi. 1 f. 2. Forma 

 cellulis prae latitudine longioribus. Long. 239, lat. 38, apex 

 circ. 9 ft. [N:o 952] — This form is longer and slenderer 

 than the typical one. Moreover the pyrenoids are more 

 numerous (6 in each semicell). Cell-wall entirely smooth but 

 conspicuously yellowish coloured. Apex broadly rounded. 

 Compare also C. spetsbergense Borge, Siissw. Alg. Spitzbg. 

 pi. 1 f. 5, which is narrower at the truncate apices („sub 



r ) NB. The numbers in brackets ^N:o] refer to my collection 

 of original figures. 



