2 F. E. FRITSCH. 



species in common, and the representation of the main groups is rather different. The 

 collections made by the members of Sir E. Shackleton's Expedition, on the other 

 hand, come from very much the same region as those which form the subject of the 

 present communication, and there is a considerable degree of resemblance between 

 them, a fact which- is especially noticeable as regards the Diatoms. Owing to the 

 very appreciable delay * which has taken place in the preparation of this report, 

 Messrs. West's report on the freshwater Algae of Sir E. Shackleton's Expedition has 

 appeared since this manuscript left my hands. Professor G. S. West was good enough 

 to forward to me in the summer diagnoses and figures of the new forms found by him 

 and his father, and for the last two months a proof of their paper has been in my hands. 

 I am glad to have this opportunity of thanking Professor West for his courtesy, which 

 has to some extent relieved the great labour of working out the collections. 



A considerable number of species and varieties are common to the -two 

 collections, and these include several of the new forms described by Messrs. West. 

 Nevertheless the present report brings a considerable number of new records and the 

 descriptions of sixteen new species and five new varieties. We may evidently look to the 

 Antarctic continent to furnish us with quite a large number of new representatives 

 of previously known genera, although thus far no new genera f have come to light. 

 This is rather surprising, as the extreme conditions under which the algal flora of the 

 Antarctic exists might be expected to lead to the development of new types. 



The distribution of genera and species in the different groups is as follows : 



Genera. Species. 



IsokontiE . . . . (j . . . . 13 



Conjugates .... 1 . . l 



Cyanophyceas . . . 17 . 52 



Diatomaceas . . . . 11 . . . . 25 



Totals . . . 85 . . . .91 



The prevalence of Cyanophyceous forms and Diatoms, which this table discloses, 

 is true also of the number of individuals. It does not appear that any green Algae 

 are common in the freshwater flora of the Antarctic, except for species of Prasiola, 

 which have long been recognised as important constituents of the flora of these 

 regions, and species of Pleurococcus or allied genera. Species of Chlamydomonadacese 

 also appear in abundance, but their occurrence is probably rather local. On the 

 other hand numerous Protococcales that are prevalent in the waters of other ' parts 

 of the earth are completely wanting, the filamentous Chlorophycese are represented 

 only by Ulotlirix, and the whole host of the Conjugates are as good as absent. The 

 discovery of a few individuals of a Desmid (cf. pp. 20-21) is of great interest in this 



* For this delay the author is alone responsible, although largely due to circumstances which were beyond 

 his control. 



t A new genus was described among the Algse of the South Orkneys (op. cit., p. 304), but this came from the 

 yellow snow flora, a type of algal flora that was previously unknown. 



