86 K. MUNSTER STROM 



distribution when dealing with each species in the following account, in con- 

 formity with the other contributions to this work. 



Only in a few cases I have mentioned the names of the collecting-places 

 proper, as they are of very little interest when such scarce material is investiga- 

 ted, but often I have made use of Prof. SKOTTSBERG's notes on the conditions 

 under which the Algae grew. 



The number of species may be apportioned as follows. 



Chlorophyceae 12. PkOTOCOCCALES I. 



Conjugate 5. Myxophyceae 13. 



OEDOGONIALES I. COCCOGONE/E 2. 



CLADOPHORALES 3. HORMOGONE^E II. 



Ch/ETOphorales 2. Total 25. 



As to be seen from this, the number of species in the Myxophyceae was 

 relatively large. The ecological groups of Algae, which were best represented 

 were the Algae of wet and dripping rocks, and a few strictly subaerial ones. 



Finally I wish to express my best thanks to Professor Dr. N. WlLLE for 

 kindly giving me his opinion on some critical species. 



Systematic account of the species observed. 



Class Chlorophyceae. 



Order Conjugatae. 

 Family Desmidiaceae. 

 Genus Cosmarium Corda. 

 1. Cosmarium subspeciosum Xordst. 

 Nordstedt: Desm. Arctoae. W. & G. S. West: British Desmidiaceaa Vol. III. 



After due consideration I have referred the specimens observed to this 

 species. Many of them closely resemble Cosmarium biuum, but in no case 

 could I observe the characteristic and indispensable markings. The nature of 

 the central tumour furnished with the vertical granulate ridges in Cosmarium 

 biuum must be regarded as the essential distinguishing feature. 



Moreover, the measurements and the number of crenations on each semi- 

 cell are in accordance with the typical form of Cosmarium subspeciosum. The 

 crenations are by no means regularly binate granulated. All these characters 

 serve to distinguish the species. 



However, the specimens observed at a first glance so much resemble cer- 

 tain forms of Cosmarium biuum that the two species may be easily confused, 

 when dealing with such forms as the present. 



