63 



The specimens from East Greenland entirely agree with 

 Rosenvinge 's exhaustive description of the species (Grl.Havalg. 

 1. c). The size of the plants is somewhat varying. Young 

 plants 2 — 5 cm. long and 0,5 — 2 cm. broad fully resemble the 

 figures given by Rosen vinge (Grl.Havalg. fig. 48). The larger 

 specimens are 10 — 30 cm. long and 5 — 20 cm. broad. The 

 thickness of the frond varies between 39 and 44^. The species 

 was gathered in May — July, and September, with zoospores in 

 June, July, and September. In a single place it is said to have 

 been dredged up from a depth of 5 — 19 fathoms. 



As well known,^ Rosen vinge found (1. c), that this species 

 contains two chromatophores in each cell, one in each end of 

 the cell, facing each of the two sides of the frond. In this 

 respect M. fuscum differs from other species of Monostroma 

 as, for example, M. Grevillei, which only contains one chro- 

 matophore in each cell facing the primary surface of the frond 

 (Rosenv. 1, c). The occurrence of two chromatophores in each 

 cell in M. fuscum is highly important and should be mentioned 

 in the description of the species^). 



Gr. or.: Tasiusak, Ikerasak, Tiningnekelak, Angmagsivik, Smal- 

 sund, Nualik. 



102. M. leptodermum Kjellm., K. Rosenv. Grl. Havalg. p. 944, 

 Deux. Mém. p. 117. 



The largest specimen collected is 21 cm. long, and its 

 largest breadth is 14 cm. Right above the tubular stipe the 

 frond is 10 fi thick. The specimens are well agreeing with 

 typical plants of this species, except in the largeness of the 

 frond. The plants were collected in July. 



Gr. or.: Tiningnekelak. 



') F. S. Collins (The Ulvaceæ of North America, Rhodora, Journal of the 

 New England Botanical Club, Vol.5, No. 1, 1903) does not at all men- 

 tion this important character neither in the description of the species 

 nor in the description of the genus Monostroma. 



