394 



JOHS. HOYE PKTKRSEN 



ri)stratis; striis piuicUitis railianlibiis vel :i|)iif paiallt-lis; ari-a apicali 

 anj^usta; area cenlrali roUiiidala vol in fasciaiu traiisapicaicni unilalera- 

 liter vi'l hilatcralilcr dilatala. Fi{^. 19. 



Lonj5. 9-24 //. lat. 0—6,3 //. striis IS 20 in \0 u. 



E. Icol. L. 131 — X. Iccl. L. 1()1. L. 1(;2, L. 17 3. L. 242. L. 252, 256 — 

 N. W. Icel. 268 - W. Iccl. L. 297. L. 29S. L. 309, 327 — S. Iccl. L. 282, 



L. 295. L. 352, L. 353. L. 372. L. 381. 



Fig. li). Savicula nilrophila 

 Boye l\ n. s|). X 1200) 



.\ railler variable .species ol' which, 

 howevcr. I do not find any reason lo set 

 up varietles since Ihe varioiis forms are 

 roiiiid inlerniixed aiiioii^ each ollier and 

 willi Iransilional lornis. Quitc small 

 spccimcns occiir of oval shapc wilh 

 roundcd or sli[<lilly Iruncate apices 

 1^1. 9/<. br. 5//, sir. abl. 20), and wilh a 

 round central area. I.arj^er spccimcns 

 occur wilh ncarly lanceolatc valves wilh 

 rostratc apices, wilh Ihe central area round or more or Icss transversally 

 expanded. sometimes rcachinf^ Ihc edgc of the valve on one side. L. 12— 

 17//, br. 6.2//, sir. 18). Finally large s|)ccimens are found in which the 

 valve is linear wilh rostratc ajiiccs and a broad lransa|)ical fascia. (L. 24//, 

 br. 6//, str. 18). These specimens somewhat resemble N. Borrichii but 

 difVer plainly from this species in the striæ nol bcing radiale al the 

 apices and csjiccially by Iheir appcarance in the girdlc view. The valves 

 are slightly silicilied which oftcn gives thcm an irrcgular appcarance as 

 a conse(|uence of Ihe preparalion. I have found the species in 18 samples 

 in all, ncarly all derived from the immediale vicinily of houses, in piaces 

 wherc there was abundant maiuire and therefore a copious vegetation 

 ui J'rasiola crisj)a and other nitr()|)hilous species. In 14 of the 18 sani|)les 

 it was found among Pnisiulu (■risj>a . Xaoiciila nilrophihi ilself must there- 

 fore be regarded as a pronounced nilrophilous species. Everylhing 

 would scem lo indicatc that il will withsland strong desiccalion, it having 

 in manv cases been Ibund on fences. 



Navicula Rotæana Uabh. var. oblongella Grun. Cleve Syn. I, \^. 128. 

 Van Heurck Syn. IM. 11. lig. 21. 



E. Icel. 25, 129 — W. Icel. 297. 298 - S. Iccl. 295. 



The median striæ were somewhat wider apart than the rest. the 

 spaccs belween these were very small so lliat they wcrc alniost confluent, 

 a strialion which is also found e. g. in Wpu/mla Kiit/. Only n-fi 



few specimens were found in cach sam])lc, and in no case 

 could cell conlcnls be obscrved. ^ 



Navicula thermicola Boye V. n. sp. 



Valvis ()l)l()ngis. j)ro(hiclo-capitalis. long. 13//. lat. 3,.3//. 



J 



striis in medio 18 in 10 //. apices versus densioribus; area •^"""'"''' 

 1- . ' ,. . n ■ ■ . ... Ihcrnticohi 



apicali angusla. area cenlrali in fasciam Iransapicalcm <lila- jj<,yj.p. „.sp, 



lata; nodulis tcrminalibus in coslas apicales protractis. Fig. 20. (X 1200). 



