KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 61. NIO II. 19 



Petroderma Kttck. 



P. maculiformc (Wollny) Kuck. — Fig. 8 a— d. 



South Georgia: Bay of Isles, in the sublit. region on rocks, 8 m (St. 52, 

 25. 4. 09, sp.). — Known before from the North Atlantic. My specimens seem to 

 agree with Kucktjck's description and figures in almost every respect (Beiträge II, 

 p. 282). There are pecnliar swollen cells in my plants, with yellowish brown, strongly 

 refractive contents. They look abnormal. 



Distribution: Fseroes, Ireland, Heligoland, S. Georgia. 



Lithoderma Aresch. 



L. piliferum nov. spec. — Fig. 8 e — m. 



Maculas orbiculares minutas, 1 — 3 mm diam., centro 60 — 90 jj. crassas formans. 

 Cellulse strati basalis in centro subhexagona?, versus marginem magis rectangulares, 

 chromatophoris disciformibus sat numerosis instructse. Plantula? a 1 i se cellulis majori- 

 bus, centralibus 9 — 12jj. diam., submarginalibus 15—30 X 12^, filis erectis (semper arcte 

 cohserentibus) 12 — 14 ij. latis, sporangiis terminalibus (raro inventis) subglobosis, circ. 

 15 {i diam., pilis 8 — 9;j. crassis; a 1 1 e r se cellulis minoribus, centralibus 6 — 9 [idiam., 

 submarginalibus 12 — 15x6—8^, filis erectis 8 — 10 ji crassis, sporangiis nullis inventis, 

 pilis 6 — 7 [i diam.; sed adsunt etiam nonnullae typi secundi sed aliquantulum majores, 

 vera3 intermediae autem non observatse. Gametangia ignota. 



Falkland Islands: Port Louis, on a piece of bottle glass picked up in 

 a tide-pool (St. 11, 7. 2. 08, sp.). — The growth takes place exactly as described by 

 Kjellman, Handb. p. 17. A comparison with the illustrations of L. fatiscens in 

 Hauck, Meeresalg. p. 403, fig. 177 will show the extreme likeness between the two 

 plants: the cells in the vertical rows are 8 — 17 [a across according to Hauck, 12 — 17.5fi 

 according to Areschoug Observ. phyc. III p. 23. The presence of hairs seems to 

 forbid an identification with the northern species. Another question is if the new 

 species really belongs to Lithoderma Aresch. His genus was characterized by posses- 

 sing lateral gametangia seated on free ends of the filaments, while Kuckuck considered 

 that specimens with terminal gametangia belonged to L. fatiscens. Svedelius made 

 a new genus, Pseudolithoderma Sved. for Kucktjck's gametangium-form (Engler & 

 Prantl, Nachtr. zum I. Teil, 2 Abt. p. 176). There are no good vegetative char- 

 acters that help to a distinction of the two genera, and of sporangia only one type 

 has been found. To judge from Kuckuck's figures (Bemerk. p. 237 — 240 and Beiträge 

 Nr. II Taf. VII) the anatomical structure is the same in plants with sporangia and 

 with gametangia; still, Kylin thinks the former belong to the true Lithoderma 

 (Algenflora Schwed. Westk. p. 46). The position of L. piliferum will remain unsettled 

 until the gametangia have been discovered. Gain, Flore algol. p. 50 found a sterile 

 Lithoderma on the coast of Graham Land. He does not mention if hairs occur. The 

 plants figured by Kjellman in Alg. Aret. Sea, Pl. 26 fig. 6 differ from Lithoderma 

 in some respects but very much resemble Petroderma. 



