418 



JOHS. BOYE FKTKHSKN 



Tlic dimensions of tlie spccimcns found ran^^o wiliiiii tlu' folldwin«^ limits: 

 L. 11— 24//. br. 2.2— 2.8 //, str. more tlinn 'M). cniiiinl dols 11 1.') iii 10//, 

 Tiic species, whicli has nol prcvioiisly bccii Ibiind in Iccland, sccms 

 ])redominanlly lerresliial tlicrc, Ihoujjh it docs nol grow in very dry 

 localitics. 



IMitzschia microcephala (Irun Cl. cl (iriin. Ard. Diat. p. <)('). V. llciirck 

 Syn. IM, (il), lij^. 21. 



\V Iccl. L. 337. 



Tilis pcculiai- small s|)ecics has hillierlo only bccn known from 

 Europe (Bclgium, (icrniany. Swilzcrland, Denmark. Il was nol found 

 in any greal niimber in thc sample. 



Nitzschia perpusilla Habh. Cl. und (irun. Arct. Diat. p. 99. Van llcurck 

 Svn. PI. 09, fifi 8. 



E. Iccl. 85 



X. Iccl. L. 135. 



Tiie species has nol prcviously bccn found in Iccland, and on thc 

 Nvhole liltle is known as to ils distribution and occurrence. Hcncc il 

 is difhcull lo form any opinion as to wliclher it lives chiefly as a Icr- 

 restrial or as an aquatic species. 



Nitzschia sinuata W. Sm. Grun. Cl. und Grun. Arct. Diat. p. 82. 

 Van Hcurck Syn. IM. 60. hg. 11. 



E. kel. 85, 92, 99. 



Østrup found it in Iccland in 26 samples from fresh 

 water, hence it isevidenlly in the main a hydrophilous species. 



Nitzschia thermaiis Kiitz. var. minor Hilse. Cl. und 

 Grun. .\rct. Diat, p. 78, Van Heuick Syn. l'l. 59, lig. 22. 



.\. kel. 133. 



Found in a dricd u|) ditch soulh of Akureyri among 

 pronouncedly Icrrestrial species. 



Nitzschia vermicularis Kulz. Grun. var. terpestris 

 Boye r. n. var. 



E. Icel. L 8. 



Valva recta lineari in media parlc paululuni con- 

 slricla, apicibus prolractis; long. 50— 55 //, lal. 4,5//, slriis 

 transversis delicalissimis punclis carinalibus 6— 8 in 10//. 

 E facie conncctivali visa sigmoidca. I'ig. 31. 



I only found Ibis form of N. vermicularis in onc of 

 thc samples I cxamined, and it may perhaps bclong lo 

 Ihat kind of small forms which sevcral invcsligators have 

 found OU carth. Boye Petersen 1915, Brislitl 1920. 

 p. 40. Beger 1927. p. 391 . The fretiucntiy elongatcd 

 carinal dols arc a |)cculiar feature of Ibis form. 



lMK.:n. 



\il:schiit 



uenniciiliiris 



(.Kul/.) riruii. 



var. liTrestris 



n. var. 



(X 1200>. 



