2M8 joiis. i{()_^i; i'i:ti:hsi:.\ 



ol the tric-lionics was 1.6—2.0 //, and it af^rccd oii llic wlioli- ahsolutely 



with llu- (li:i;4n<)sis in (ioinont 1. c.i. 



.S. thciimtlis is a Iruc thermal al;;a. in tlic cases. wIumc I have 



louiul stalemciits conci-rninji tiu- tcnipcraturc al wliirli il j^rcw, llie fi- 



gures varieii bclwecn 30" and ;{.')". Nt'vcrliiclcss. it is |)robable that 



tlie varialions in tlu- UMnpcratiiie, al wliicli it is ablc lo grow, are con- 



si(ieral)lv ■'roalci-. 



"^ . 



Symploca sp. ? 



In a sam|)le collected by J. Sicenstrnp and lal)cllc(l : "On siliceous 

 sinter, (icyser. Hlcsi. Tem|). 30"."" a form oiruncd whirb closely re- 

 semblcd S. Ihernuilis : but ils shcalhs colourcd a dccp violcl wilh chlor- 

 zinc-iodine. Theretbrc it cannot bc idcnlificd with the fornier species, 

 and. as the nialcrial is so defifient, I dåre neitiier inclnde il in any of 

 the olher Ihin speeics of .S ///?!/; /o ca. 



V. Plectonema Thuret. 



Plectonema roseolum (Richter Gom. 



(ioniont, Mono-^r, II j). 102. pi. I, figs. 9—10. Witlr et Nord.st. nr. 1159. 



J'. (■(irncuni Lcmmermann 1910 p. 206. 



E. Iccl. Fljolsdahir, rocky wall over whicii waler was Irickling ^'Ve 

 1914. Hrei<\irsta6ir, on leaves from the bottom of a pond. lemp. 12*^ 

 ^h 1914. Sey(iislj6r6ur. bog at 300 m. heiglit above sea-level; among 

 mosses ^^/e 1914. — X. Icel. I Ifsbær, pool with shallow water, temp. 

 20 ** '^/7 1914. 



Area: Eur., Alaska. 



All the samples, in which I have foiind this species, have bcen pre- 

 served in alcohol. Therefore it has been impossible for me to ascertain 

 the colour of the trichomes. On the other band, the dimensions, the 

 apices and the granules at the transverse walls were seen and corre- 

 spondcd exacliy Nvilii Ihose in a tyi)ical J'. ruseoliiin. Bul Ihere is a 

 possibility that it has in laet been, in some or perhaps in all cases, P. 

 nolaluiu Schmidle Simmer 1901 p. 84) that was present. 



P. roscolnin has most fre(|uenlly been found on the panes of bol- 

 houses; bul in Alaska it has been l'ound on dripjjing rocks. The species 

 thus seems to show aérophilous tendencies. and I have found it under 

 similar conditions in Iceland. but also submersed growing on decaying 

 piants sunk lo the boltom of small pools of water. 



Plectonema nostocorum Hornet, 

 (iomonl, Monogr. II |). 102. pi. 1. lig. 11. 



Iv Icel. Pond near (irimsa. In Aphanotliece stagnina, temp. 1(3" 

 ^Ve 1914. — N. W. Icel. Dvraljort^ur Hariot (1893 p. 315), Belloc ^1894 

 p. 6). Reykjancs. hot spring (60 °j Hariot (1. c. , Melloc 1. c). 



Area: Eur., As.. Am., .\ustr. 



("lomonl wriles thai Ibis species is very common among olher algae. 

 Neverthcless it is bul known from com|)aralively few localities er. 15). 



