232 



Frederikshavn; UC, TO, 18 m and FF (Trindelen) north of L£es0. ~ Ke: ZE, Fladen; IB, Store Middel- 

 griind. — Km: XB and XC south of Kobbergrund. -- Ks: HS, Briseis Grund; OU, Schultzs Grund; 

 00, Soborghoved Grund. — Sa: KK, Klorgrund, south of Hjelm; FT, Klepperne. — Lb: Middelfart. — 

 Sb: Reef at Korsar harbour, 2m; NN, south-west of Sprogo, 19 m. — Su : Off Aalsgaarde, 2() m (H. E. 

 Petersen); TF', StalJans Flak, 14 — 18 m. — (Bm: Stones picked up near Stevns ?). 



8. Lithothanniion laevigatuni Foslie. 



Foslie, Norweg. Forms, 1895, p. 139, pi. 19, fig. 21—23; Heydrich, Litlioth. Helgoland, 1900, p. 76. 

 Lithothamnion emboloides Heydrich, Lith. Helgol., p. 74, Taf. II Fig. 1.5 (teste Foslie). 

 Phijmatolithon Icevigatum (Fosl.) Foslie, Remarks. 1905, p. 79. 



Judging from Danish specimens, this species appears to be quite distinct from 

 L. polymorphum, whereas, according to Foslie (Remarks, p. 79), in more southern 

 localities there is no distinct limit between these two species. L. Icevigatum is charac- 

 terized by a comparatively thin, smooth crust, up to 0,5 mm thick, by the roof of 

 the sporangial conceptacles disappearing after the evacuation of the sporangia, and 

 by the two-parted sporangia. When occurring together with L. polymorphum, the 

 difference between them is evident; the two species are, however, only rarely met 

 with in the same locality, and it must be emphasized that L. polymorphum does 

 not occur in the Limfjord, where L. Icevigatum has been met with in several loca- 

 lities. I therefore do not doubt that they are specifically distinct. 



The anatomical structure much resembles that of L. polymorphum. The hypo- 

 thallium is similar, but is sometimes more fully developed. Its cells were found to 

 be 18- 21 long, 4,5 — 7 />. broad. The cells of the perithallium were less variable 



in breadth than those of L. poly- 

 morphum; they were almost al- 

 ways 6—7 // thick. The length 

 was usually 6 — 9/^, most frequently 

 7 — 8//, or only little greater than 

 the breadth, and the rounded cells 

 thus approach the spherical form ; 

 but cells shorter than broad are 

 also met with (fig. 151 A). Trans- 

 verse fusions occur here and there, 

 in the hypothallium and the peri- 

 thallium as well. Starch grains 

 are frequently present as single 

 grains in great numbers in most 

 of the cells, except the uppermost. 

 Only sporangial conceptacles were 

 met with. They resemble those of L. polymorphum, and the hollow containing the 

 roof is, as in that species, sometimes very slight or wanting, and the elevated border 

 may also be wanting, the surface over the conceplacle thus being quite even or with 



B 



Fig. 150. 



Lilholliamnion hruitjatiini. Verticnl sections of crust from Hols;i\cii. 

 Sb, showing spor:ingiaI conceptacles and limiting lines between llie 

 zones, tig. I) also the hypothallium. 65:1. 



