KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND. 20. N:0 5, 293 
Gen. Ulva (L.) Wirrr. 
Monostr., p. 9; L. Syst. Nat. Ed. 10, p. 1346, 
Ulva crassa KJevum. 
Spetsb. Thall. 2, p. 44. 
Descr. et Fig. Ulva crassa KsEuum. |. c. et t. 3. 
Syn. Ulva crassa KJeium. |. c. et Algenv. Murm. Meer. p. 51. 
» latissima KseLiM. Vinteralgv. p, 65. 
Remark on this species. Since I have had the opportunity of examining a greater 
number of forms of Ulva from different parts of the Scandinavian coast and especially 
from the north coast of Norway, I have found that U. crassa is not such an indepen- 
dent form as I believed at the time when I described it. It is nearly related to U. 
lactuca, but it differs from that species by greater thickness, the greater height of the 
cells, the smaller transverse diameter of the cell-rooms and by more abundant endo- 
chrome. Until it has been fully demonstrated that these characteristics cannot be 
employed as specific differences in the genus of Ulva, I think U. crassa ought to be 
retained as a separate species. 
Habitat. It grows sublitoral in 3—5 fathoms water, attached to other alge and 
to stones, always scattered and in sheltered localities, On the coast of Spitzbergen it 
occurs also in winter. I found young individuals at Musselbay in Noveinber, January, 
and April and an older specimen with zoospores on the 23 December. I have besides 
taken specimens bearing zoospores in July and August on the coast of Spitzbergen, and 
in July on the west coast of Novaya Zemlya. 
Geogr. Distrib. This species belongs to the arctic region of the Polar Sea, but 
judging from one very fragmentary specimen occurs also on the north coast of Norway. 
Greater numbers of it have not been met with anywhere. Its most northern point is 
Musselbay on the north coast of Spitzbergen Lat. N. 79° 53’. 
Localities: The Norwegian Polar Sea: Finmarken at Oxfjord, only one incomplete 
specimen found. 
The Greenland Sea: on the north and west coasts of Spitzbergen, rather commonly 
dispersed, but always scarce. 
The Murman Sea: on the west coast of Novaya Zemlya local and very scarce. 
Ulva lactuca L. 
Spec. Pl. °2, p. 1163. 
Descr. et Fig. Ulva lactuca Born. ct Tuur. Etud. Phycol. p. 5 et t. 2—3. 
Syn. Ulva latissima Nord]. Alg. p. 40. 
» » ScHUBELER, in Heugl. Reise, p. 317 (?). 
» linza ArescH. Phye. Seand. p. 410 (?). 
» »  KDEEN, 1. c. (?). 
