178 KAARE MÜNSTER STRØM. 



188. Cosmariwm Quadrum. Lund. 

 forma. 



This desmid occurred in great quantities in two samples 

 obtained from boggy springs. The cells were very variable in 

 outline. Many of them had a slightly incurved apex, and others 

 the convex apex as on my drawing, but all intermediate forms 

 were observed. The granulation was also variable. The granules 

 are different both in size and with regard to Ihe distance between 

 them. Apex is oftener without warts (as the figure), but it may 

 also have them. 



Size: long. 60-66 /^ lat. 50-53 ii, lat. isthm. 23— 23,5 ^<, 

 crass. 30 ,«. PI. IV, Figs. 5 & 6. 



I think that this species is to be best referred to C. Quadrum, 

 but it differs in various points. To G. margaritatum it can 

 not be referred as the apex often is incurved. The gi*anules 

 are not so regularly arranged on my figure as in the drawings 

 of LuNDELL and West, but I have fixed every granule to its 

 right place with means of camera lucida. 



189. Cosmarium amoenum. Breb. 



Very frequent. Indeed, this species was one of the com 

 moner desmids at Tuddal, especially at the lower altitudes. 



190. Cosmarium crenatum. Ralfs. 

 General, but by no means abundant. 



191. Cosmarium taxichondrum. Lund. 



This rare species was observed in some quantity in a single 

 sample. The cells differed somewhat from the type. 

 PI. IV, Fig. 7. 

 Addenda to the genus Cosm,arium. 



192. Cosmarium diplosporum. (Lund.) Lütkem. 

 Cylindrocystis diplospora. Lund. Desm. Suec. 

 Rare, only in a few samples. 



Genus Xanthidium. Ehrbg. 1837. 



193. Xanthidium armatum. (Breb.) Rabh. 

 Rare, only observed from a single locality. 



