KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 61. N:0 II. 15 



Hecatonema Satjv. 

 H. maculans (Collins) Sauv. — Fig. 6 a— c. 



Patagonia: Skyring Water, beach drift near Punta Rocallosa, on leaves of 

 Macrocystis (29. 4. 08, gt.). — The occurrence of this northern species is perhaps unex- 

 pected, but I am unable to discover any distinctive characters. The plant was first 

 described from North America, but has låter been found in many places along the coasts 

 of Europé. It is variable, and Sauvageau described three forms, of which our specimens 

 agree with no. 1. The dimensions are: cells of basal disc 10— 15 [x across, erect fila- 

 ments c. 12 tx thick, hairs 10 — ] 3 ^., gametangia 65— 80 X 20 — 25 [x; Sauvageau's fig- 

 ures are: filaments 10— 16a, hairs 10 — 14[x, gametangia 50 — 75 x 17 — 26jx. 



Distribution: Atlantic coasts of N. Amer. and Europé, S. Patagonia. 



Myrionema Grev. 



M. incommodum Skottsb. Ant. Meeresalg. I, p. 52, Fig. 56 — 60. — Fig. 6 d — h. 



Patagonia: Fitzroy Channel, Los Amigos, on Leathesia (St. 17 b, 19. 4. 08, sp. 

 & gt.). F u e g i a: Puerto Barrow, on Adenocystis (St. 42, 4. 3. 09, sp. & gt.). Falk- 

 land Islands, Cape Pembroke, on Scytosiphon (St. 3, 7. 11. 07, gt.). — Of this 

 species new and very good material was obtained. As was pointed out by the writer, the 

 basal disc gets dissol ved and the horizontal filaments creep quite free between the 

 assimilators of Adenocystis; in the new material there is nothing at all that deserves 

 the name of a compact thallus, even on a smooth surface. In the loose tissue of 

 Leathesia the filaments become more or less endophytic and the whole plant resem- 

 bles Strepsithalia Sauv., but a closer comparison seems to show that it must be the 

 same as the rest. 



If Foslie's Ulonema is retained, M. incommodum should belong to that genus 

 But Sauvageau, who made a very careful comparison between U. rhizophorum Fosl. 

 and M. vulgäre Thur., could find no other difference than in the disc. A tendency 

 to a dissolution of the margin may be observed in other species as well, and it should 

 not be forgotten that there is a forma soluta Collins of Hecatonema maculans (Rho- 

 dora, 1906). 



M . incommodum is very like certain forms of M. vulgäre, especially the »Ulonema». 

 But the length of the erect filaments (assimilators) is generally greater in my species, 

 150 — 175 [j. or even more; they are more club-shaped (compare, however, Sauvageau, 

 fig. 7 A on p. 201), with the basal cells long, slender and poor in chromatophores. 

 Very often two assimilators are borne by a common stipe. They are 9 — 10 [x thick 

 as are also the hairs. The sporangia measure 40 — 65x25 — 30 fx, the gametangia 

 20 — 35 x 10— 12 [x; they are 1 — 2-seriate. Both assimilators and reproductive organs 

 appear to have been rather poorly developed in my former material, and the original 

 description is incomplete. There is, however, no doubt about the identity. 



I strongly believe that M. incommodum is the same plant that was found by 

 Kjellman on Adenocystis from Port Arthur, Tasmania, and spöken of as Myrionema 



