— 351 — 



M. latissimum (Kütz ) Wittr., but it well agrees with M. arcticum Wittr. I 

 found moreover in Strömfelt's collection an undetermined specimen, col- 

 lected by him in E. Icel., Seyöisfjöröur, 14. Juli 1883, which also belongs 

 to this variety. 



var. intestini formis Rosenv. 1. c. ; Enteromorpha intestinalis Strömf. 

 p. 58 partim (e specim.). 



This variety has only been found in two places in Iceland, in E. Icel. 

 at Hölmanes in Reyöarfjöröur (Ström felt) and in SW. Icel. at Reykjavik 

 (G. 0.). The specimens gathered by Strömfeit were by him determined 

 as Enteromorpha intestinalis, and in his book (1. c.) mentioned as follows : 

 „I found at Hölmanes in a depth of 2 — 3 fathoms an unusually large 

 f. genuina (= var. maxima auct. ?) ; one of the specimens was more 

 than 40 cm. long and up to 10 cm. wide". This variety resembles also 

 higly a large Enteromorpha intestinalis , and can with certainty be sepa- 

 rated from it only by anatomical characters. I have seen Strömfelt's 

 specimens, the longest of them is 45 cm. long, the broadest 16 cm. broad 

 in dry condition. They are 25 — 36 fi thick, and the base of the plants 

 agrees well with the Greenlandic specimens. The specimens gathered by 

 Ostenfeld at Reykjavik were found floating in the sea near the coast. 

 There are only two fragments without the base, the one 43 cm. long 

 and 3 cm. broad, the other 23 cm. long and 9 cm. broad, both in dry 

 condition. The thickness of the frond is 24 — 31 pt. 



Strömfelt's specimens agree very well with Rosenvinge's description 

 of this variety; Ostenfeld's specimens I have on account of the thickness 

 of the frond referred to this variety rather than to the nearly related vai\ 

 Vahlii (J. Ag.) Rosenv., which according to Rosen vinge (1. c.) is somewhat 

 thinner (15—25 fi). 



var. typica and var. arctica are common along the coasts. 



Monostroma undulatum Wittr. Monostr. p. 46, Tab. Ill, fig. 9 ; Rosenv. 

 Grl. Havalg. p. 945; Monostroma Grevillei Strömf. Algveg. p. 54 partim 

 (e specim.). 



It occurs in pools and on other algæ : e. g. Rhodymenia palmata and 

 Chordaria flagelliformis in the litoral region and in the upper sublitoral 

 region down to a depth of about 14 fathoms, frequently on the stems of 

 Laminaria. It has been collected with zoospores in April— June. The 

 Icelandic specimens are 5 — 30 cm. long, 2 — 15 cm. broad and 20 — 30^ 

 thick. They are broadest either below, in the middle or above ; the base 

 is cordate or cuneate. My specimens agree very well with Wittrock' s 

 description except that they are somewhat thinner. According to Wittrock 

 (I.e.), the thickness of the typical M. undulatum is 40 — 50/^, the Green- 



23* 



