342 TRANSACTIONS AND PKOCEEDINGS OF THE [Sess. Lix. 



The locality is of great interest to the Algologist, and 

 is well deserving of being thoroughly explored, not only 

 on account of the luxuriance of the Algfe, but for the 

 information to be gained relative to the geographical 

 distribution of species. The species will often be found to 

 have different habitats, — as well as different host-plants, — 

 from those commonly observed in the southern islands, and 

 in Scotland generally. They are altogether more northern 

 in character. 



At the west of the island, where the dip of the argill- 

 aceous-sandstone strata is at a gentle angle to the west, 

 the pools between tide marks are numerous at all levels, 

 and are of greatly varying depths. In these pools, especially, 

 the AlgfE are to be found growing in luxuriance, repre- 

 senting many species. 



Notwithstanding indifferent health and failing sight, I 

 succeeded in collecting 123 distinct species, including 

 many rarities, in the course of a fortnight's work last 

 August ; but that number would doubtless have been 

 considerably increased had my time been less limited. 

 Of these, the following ten have not hitherto been observed 

 in Orkney : — 



1. Dictyosiphon Ghordaria, Aresch. ; forma gelatinosa, 

 Eeinke. — In shallow pools at a high level. Not un- 

 common at Eisegjo, also at Noustar, and at South Bay, 

 S.E. from Howmae, sometimes in bushy, robust specimens. 

 Mr. E. Batters, to whom I am greatly indebted for his 

 kindness in examining part of my North Eonaldsay 

 collection, and in identifying this, amongst other doubtful 

 species, informs me that these correspond with the 

 specimens gathered by Eeinke and sent out by him in 

 the " Phycotheca Universalis," and that they, probably, 

 should be referred to his forma gelatinosa, which comes 

 very near to Dictyosiphon Mesogloia, Aresch,, and forms a 

 connecting link between the two species. Dictyosiphon 

 Chordaria was first found in Britain by Mr. Batters at 

 Berwick-on-Tweed, and he subsequently found it at 

 Cumbrae, while on the British Museum Working Com- 

 mittee, which was formed for the investigation of the 

 Marine Flora of western Scotland. It is properly a 

 Scandinavian species. 



