486 



appears to differ soraewhat from this species and it is perhaps 

 doubtful whether it belongs to it at all (cfr. Rosenv., Grønl. Havalg, 

 p. 938, and Wille, Færoernes Ferskvandsalger, p. 53). 



With regard to its habitat Wille writes (1. c. p. 14): — »Sie 

 wuchs anf der Schattenseite am hochsten Wasserstandszeichen, so 

 dass sie nur bei Springflut oder starken Wellenschlag von Salz- 

 wasser benetzt werden konnte, und deshalb abwechselnd der Durch- 

 netzung mit Salz- und Regenwasser ausgesetzt war.« This corres- 

 ponds in the main with its distribution along the sheltered coasts of 

 the Færoes, while along the open coasts, according as the place 

 is more or less exposed, it occurs from several feet above high- 

 water mark to upwards of at least 40 feet above it. Nor does it 

 grow here exclusively on the shady sides of the rocks, but it also 

 occurs in open piaces facing south and exposed to the sun. Conse- 

 quently, it is often quite dried, and naturally enough in such habi- 

 tats it is also often liable to be wetted only by freshwater for a 

 longer period at a time. 



This species has been observed along the coasts of the Færoes 



in the summer and autumn months and doubtless occurs there all 



the year round. 



It is presuinably very common along the coasts of the Færoes, but 

 is often difficult to gather off the steep rocks; it has hitherto been 

 found in the following piaces: — Svino(!); Vi der 6: Kvanncsund (H. J.); 

 Øst.: Skaalefjord (H. J.); Str. : between Hojvig and Skandsetangen (!), 

 Gliversnæs (!) ; Lille Dimon (!). 



subspec. terrestris (Roth). Ulva terrestris Rolh. Lyngb., Hydro- 

 phyt., p. 32. 



This is recorded from the Færoes also as a marine alga by Lyng- 

 bye (1. c), who writes: — »In insulis Færoensibus in terrestribus 

 umbrosis humidis, et ad rupes marinas paulo supra littora, aéri 

 marino exposita.« The specimen collected by Lyngbye and pre- 

 served in the museum in Copenhagen is from Ridevig, Østero. In 

 Thorshavn and its environs I have also found Prasiola crispa grow- 

 ing in piaces where it is frequently liable to be wetted by the 

 spray, so that there is good reason to regard it also as a marine alga. 



160. P. furfuracea (Mert.) Menegh. Lagerstedl: Om algslågtet 

 Prasiola, p. 31; Imhaiiser: Entwicklungsgeschichte und Formenkreis 

 von Prasiola (Flora 1889, p. 266); Foslie, Conlrib. I, p. 127. 



Found on rocks along the shore where it is completely washed 

 by the waves when the sea is rough. The speciinens agree well 



