— 371 — 



branches, the specimen reminds of A. incurva, but in other respects it 

 most resembles A. hystrix. The last named species seems thus to be 

 less distinctly separated from other species of Acrosiphonia, especially 

 A. incurva as here understood. In this respect my material agrees with 

 the Greenlandic material described by Rosenvinge (Grl. Havalg. p. 907 — 908); 

 he remarks (I.e.) about y hystrix: „cum forma typica" (o : Spongomorpha 

 arcta f. typica Fosl. Wittr. & Nordst. Exs. No. 612 = A. incurva Kjellm.) 

 „formis intermediis arete conjuncta". 



E. Icel. Berufjöröur, Vattarnes ; Eskifjöröur (Strömfeit) ; Seyöisfjöröur. 



N. Icel. Eyjafjöröur. 



NW. Icel. Grimsey in Hünaflöi (Hj. Jensen) ; Önundarfjöröur (Ldbk.) ; 

 Dyrafjöröur (G. O.). 



SW. Icel. Stykkishölmur, Reykjavik. 



Acrosiphonia flabelliformis nov. spec. (?) 



I have at Vestman- 

 naeyjar met with some 

 peculiar specimens of an 

 Acrosiphonia growing in 

 more sheltered situations 

 in the litoral region on 

 a very exposed coast. 

 The plants were for the 

 most part left dry during 

 the ebb. Lying prostrate 

 on the rocks they had 

 a very peculiar appear- 

 ance on account of the 

 rigid upper branches and 

 their flabelliform bran- 

 ching. The plants are 

 9 — 10 cm. high. The 

 main branches are 140 

 —200 ft thick below, 

 about 260 fx in the 

 middle and 230 fx above. 

 The branches of the last order are of about the same thickness as the 

 main branches and measure about 260 fx a little below the apical cell. 

 The cells of the old branches are as long as broad or up to three times 

 broader than their length, while the cells of the younger branches, in 

 which vegetative divisions take place, usually are longer than their breadth. 

 The chromatophores of the younger cells are finely reticulated, while the 

 meshes of the chromatophores of older cells are somewhat larger and of 



abc 

 Fig. 15. Acrosiphonia flabelliformis. 

 a the lower part of a main branch with lateral 

 branches furnished with rhizoids, b the middle part 

 of a main branch the cells of which contain starch 

 in large quantities, c the uppermost part of a branch, 

 with two branches of the last order. (10: 1.) 



