168 H. JONSSON 



stagnea and Leathesia (living from June to September). In addition 

 there are species which may be supposed to be annual, as for 

 example, Punctaria, Stictyosiphon , Scytosiphon (?), Phyllitis, the ma- 

 jority of the Dictyosiphonacece, Chorda-species, etc. 



Of Red Algae the following must be presumed to be annual: 

 Bangia, Porphyra-species, Porphyropsis, Conchocelis, Chantransia- 

 species, Cera/nzum-species and possibly several more. As regards 

 Porphyra ambilicalis it should, however, be stated that it has been 

 found at all seasons of the year and at Reykjavik it occurs as 

 luxuriantly in December January as during the spring. 



B. Perennial Algae. With regard to some of the species it 

 is difficult to decide whether they are perennial or annual, as our 

 knowledge of them is incomplete; consequently it is sometimes a 

 matter of opinion whether they are to be included in the one or 

 in the other group. Only a few of the Green Algse are perennial, 

 as for instance, the majority of the Acrosiphonia-species. The latter, 

 besides being reproduced by spores, have also abundant vegetative 

 reproduction by means of offshoots; and some of them, as for in- 

 stance, A. albescens and others, live all the year round in the semi- 

 littoral zone. 



Of the Brown Algae the Fucacece and the Laminariacew are 

 perennial. It is, however, doubtful whether we are justified in in- 

 cluding Saccorrhiza dermatodea among the perennials. At Reykjavik 

 I have seen only old fruiting specimens in the winter, and judging 

 from their appearance it is very probable that they die during the 

 winter; nothing can, however, be stated with certainty regarding 

 this point. 



In the fjords of E. Iceland large individuals of this species were 

 growing in the sublittoral zone; I believe they were more than one 

 year old, but I could not prove this. In Greenland (Rosen vinge, 

 61, p. 852) perennial or upwards of a year old individuals of this 

 species occur. 



With regard to several other species of Brown Algae it is not 

 easy to say at present whether they are annual or perennial. I 

 think, however, that the following may be classed as perennial :- 

 Lithoderma, /?a//sza-species, Sphacelaria-species, Chcetopteris, Desma- 

 restia acu/ea/a, D. ligulata, Chordaria flagelliformis (?). 



I think that the majority of the Red Algae are perennial or 

 can, at any rate, live through more than one growth-period. I shall, 



