;i72 .lOHS. HOYK PKTKRSKN 



II. Tabellarieæ. 



Tdhclhirid l'Jirl). 



Tabellaria fenestrata Lyiij^b. Kut/. V. Ilcurck Traitr p. i^riO, IM 11 

 lij;. 4 77. 



E. Iccl. 2.-). 



Only a fow spccinicns observcd. It is cvidenlly of erratic occurrcncc. 



Tabellaria flocculosa l>t'lli Kiilz. \an Hciirclv Trailé, p. 337, l'l. 1 1 

 fig. 478. 



E. Iccl. 25. 129. 



Ni) ddubt liic nccurrcncc is merely accidcntal, as in liic |)reccding 

 form. The spccimens have hardly lived in the localities mentioned rocks). 



Diatomella Grev. 



Diatomella Balfouriana (irev. \V. .Smith Hr. Diat. II, Tab. GI, lig. 383. 



E. Iccl. 8. 14, L. 24, L. 25, 40, 70, 77, 78, L. 85, L. 92, L. 99, 112, 

 113, L. 114, L. 124, L. 128, L. 129. 



N. Iccl. 133, 135, 137, 162. 169, 179, 184, 185. 241, 242. 252, 256. 

 W. Icel. 294, 307, 321. 336, 338. 

 S. Iccl. L. ?294, 295, 372, 386. 



Didlomclhi lUilfouriuna is a pronounced Arctic-Alpine species, thriving 

 cspecially on irroratcd rocks with mosses or algæ ^sec cg. Hustedt 

 1924 p. 550, V. Schonfeldt 1913 p. 271 Hustedt, however, savs (I. c.) 

 that it only grows »im Urgebirge«. In Iceland, however. jjrimitive rock 

 d(»es nol occiir. \Ve must thcn suppose thai most probably il only grows 

 on eruptive rocks and cspecially nol on limcslone rocks. In Ibis connec- 

 lion it is remarkable too thai the species has nol bcen lound in Den- 

 mark. 



Ostrup found it in Iceland in 168 samples from fresh water. In 

 most of the above-mentioned samples I only found few specimcns. and 

 it was nol possible lo sce any ccll contents. In this species, however, 

 the chromatophores are but litllc conspicuous in the dried material, so 

 Ihcre mav possibly have bcen spccimens wilh endochrome in not a few 

 nn)re samples Ihan Ihc 7 in which I have secn Ihcm with ccrlainty. 

 On Ihe olher band Ihc fruslules are rather slrong, and Ihus no doubt ver\' 

 durable, so that \ve might cxpecl lo lind the emply fruslules in piaces 

 whcre the species has not lived. It is, however, remarkable that 6 of 

 the 7 samples are derived from rocks, or mosses on rocks, that wcre 

 more or Icss dam|). 



It was known from early times and has again bcen jjointed out 

 by N.Carter (1922 p. 56) and Hustedt 1924 p. 550) that this species 

 is providcd wilh a Irue raphe. This circumstance vill presuiuably render 

 it well suilcd for an aerial lifc. C\). Hoyc Petersen, 1915, p. 298). 



It would seem from the data thai the species mav occur bolh as 

 an aerial and as a hydrophilous alga. 



