NO. 2 MOSSES OF AFRICAN EXPEDITION — DIXON 3 



bryoides, Hylocomium proliferum var. alpinum, and perhaps Grim- 

 mia ovata and Pohlia elongata; the remaining species having too 

 wide a range for their presence here to establish such a connection, 

 though they would lend support to it were it well established. 



It is therefore of the highest interest to find this connection 

 immensely strengthened by certain of the species in this collection, 

 which have hitherto not been known from the African continent. 

 It will be well to give these in tabulated form together with their 

 distribution as hitherto known. 



Species Distribution 



Blindia acuta (Huds.) Bry. Alpine and arctic Europe and North America; 

 Eur. Caucasus; Central Asia. 



Aulac omnium turgidum Higher Alps of Europe; Arctic regions; 



Schwaegr. mountains of North America and Japan. 



Neckera complanata (L.) Temperate regions of Europe and western 



Huebn. Asia, and eastern North America. 



Callicrgon sarmentosum var. (Of type) Alpine-arctic regions of Europe, 

 subflavum Ferg. Asia, and North America ; Fuegia ; South 



Georgia; Alps of New Zealand. 



Moreover, the plant described below as Hygroamblystegium pro- 

 cerum sp. nov. is extremely near to and possibly should be considered 

 a subspecies of II. fflicinum, the range of which is northern and 

 alpine Europe, Asia, and North America, and New Zealand; and 

 Callicrgon Keniac sp. nov. belongs to a genus the representatives of 

 which are exclusively confined to the arctic and cold-temperate 

 regions, and almost entirely to those of the northern hemisphere. 



The above listed species are so distinctively plants of a compara- 

 tively limited area of the alpine-arctic districts of the pakearctic 

 region, that (taken with the two or three species referred to above) 

 they can hardly be explained, I think, without postulating a bridge, 

 at some time or other, between the two areas. 



Engler (8) has discussed at some length the problem of the 

 presence of representatives — either identical or as racial forms — of 

 arctic-alpine plants at high elevations on the mountains of Central 

 Africa, citing especially certain grasses and flowering plants (e. g., 

 Luzula spicata, Anthoxantlium odoratum, Koclcria cristata, Sitbit- 

 laria aquatica). His general conclusion is in favor of what may be 

 termed a fortuitous transport, rather than a definite migration. He 

 holds that there has been no continuous continental connection at any 

 time, such as would provide the conditions necessary for a migration 

 of plants of the colder European regions across northern or north- 



