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E. I c el. Reyöarfjöröur, Seyöisfjöröur. 

 N. Icel. Eyjafjöröur. 



Ulva Lactuca L., Rosenv. Grl. Havalg. p. 939 ; Strömf. Algveg. p. 54. 



This species occurs in litoral pools and in the upper sublitoral region 

 down to a depth of 2 — 5 fathoms. A specimen collected by Mr. Lund- 

 beck has been picked up from a depth of 1 1 fathoms. The Icelandic 

 specimens are 8 — 20 cm. long, 3 — 20 cm. broad and 50—70 p. thick. It 

 has been collected with zoospores in May — August. 



NW. Icel. Broddanes; Önundarfjöröur (Ldbk.). 



SW. Icel. Stykkishölmur, Olafsvik, Sandur, Reykjavik. 



S. Icel. Eyrarbakki (Strömfeit); Vestmannaeyjar. 



Fam. Prasiolaceæ. 

 Prasiola polyrhiza (K. Rosenv.). 



Gayella polyrhiza Rosenv. Grl. Havalg. p. 936. Prasiola crispa (Lightf.) 

 Menegh., subsp. marina Börgesen Fær. Alg. p. 482. 



Prasiola crispa f. submarina Wille, Studien p. 13. 



Börgesen (1. c.) unites the genus Gayella with Prasiola as he in the 

 rich Færoese material of Gayella polyrhiza besides filaments consisting of 

 one row of cells, furnished with rhizoids and filaments composed of many 

 rows of cells, divided in all directions, found specimens consisting of 

 monostromatic discs. He moreover includes Gayella polyrhiza in Prasiola 

 crispa as a subspecies under the name of *marina, which essentially differs 

 from the subsp. terrestris besides other characters by the divisions of the 

 filaments in all directions. On account of this character I think that 

 Gayella polyrhiza might as well be regarded as an independent species, 

 Prasiola polyrhiza (K. Rosenv.), as a subsp. marina of Prasiola crispa. 



I have only had a scanty material of Gayella polyrhiza from Iceland, 

 and it has only been met with in two places, growing at high-water mark 

 or above it. In SW. Iceland it occurred in company with Prasiola stipi- 

 tata in a pool above high-water mark. The filaments consisting only of 

 one row of cells were furnished with rhizoids, and resembled precisely 

 the figures given by Rosenvinge (1. c. fig. 45 D, F), Wille (I. c. Tab. I, 

 fig. 41—44) and Börgesen (1. c. fig. 99 c, e, h, g). 



The specimens from S. Iceland were composed of many cell-rows 

 and divided in all directions, fully resembling Rosenvinge's fig. 46 A (1. c). 

 The specimens occurred at high-water mark in company with Ulothrix 

 flacca and Urospora mirabilis. 



SW. Icel. Skarfaklettur near Viöey. 

 S. Icel. Vestmannaeyjar. 



