PLATK LI I. 



Fig. l,—Plagio(jmmma srrptrum ^rmiii (valviH view). KnUirgcd :^75 diameters. Deweription, p. 32«>. 



Fig, 2,— Plagif) fframm.il .saptrum Mann (zonal view). Enlarged 375 (Haiiieteis. De.scrii>tiun, p. 32i>. 



Fig. 3,—Nai1cula vkJoriehii Grun. (form). Enlnr^^erl 560 diameters. Description, p. 358. 



Fig. •\.—Navicuia ciirvilinmta Jfann. Knlur^^ed ol5 diameters. Description, p. 311. 



Fig. r\—yarfriil<i fipccioaa ^rann. I^:nlarged 550 dinmeters, Deserijttioii, p. 356. 



Fk;. e*,—Navicula gyrinida Mann. Kularged GilO diameters, Duscripticju, p. 341. 



Fig. 1.—\avirula spuma Mann. Enlarged 600 diameters. Description, p. 357. 



438 



