9 Pseudauliscus radiatus (Bail.) Rattr. 29 10 Pseudauliscus spinosus (Christian) Rattr. 29 [Illustration: PLATE 5] PLATE 6 ACTINOCYCLUS 1 Actinocyclus barkleyi var. aggregata Rattr. 27 2 Actinocyclus moniliformis Ralfs. 27 BIDDULPHIA 3 Biddulphia antediluviana (Ehr.) V. H. 32 5 Biddulphia reticulum (Ehr.) 33 6 Biddulphia favus (Ehr.) V. H. 31 7-8 Biddulphia alternans (Bail.) V. H. 33 TRINACRIA 9 Trinacria pileolus (Ehr.) Grun. 30 DITYLUM 4 Ditylum intricatum (West) Grun. 30 TERPSINOË 10 Terpsinoë americana (Bail.) Ralfs. 34 11 Terpsinoë novæ-cæsareæ Boyer 34 [Illustration: PLATE 6] PLATE 7 BIDDULPHIA 1-2-3-4 Biddulphia biddulphiana (Smith) 31 5 Biddulphia rhombus (Ehr.) Wm. Sm. 32 6 Biddulphia granulata Roper 32 7 Biddulphia turgida (Ehr.) Wm. Sm. 32 8 Biddulphia smithii (Ralfs) V. H. 32 9 Biddulphia lævis Ehr. 33 10 Biddulphia lævis Ehr. Sporangial frustules (260 diam.) 33 EUNOTOGRAMMA 11 Eunotogramma læve Grun. 33 [Illustration: PLATE 7] PLATE 8 RHABDONEMA 1-2-3 Rhabdonema arcuatum (Lyng.) Kuetz. 35 4-5-6 Rhabdonema adriaticum Kuetz. 36 7 Rhabdonema minutum Kuetz. 36 TABELLARIA 8-9-10 Tabellaria flocculosa (Roth) Kuetz. 36 11-12 Tabellaria fenestrata (Lyng.) Kuetz. 36 GRAMMATOPHORA 13-14 Grammatophora marina var. subtilissima (Bail.) V. H. 37 15-16 Grammatophora angulosa var. hamulifera (Kuetz.) Grun. 37 17-18 Grammatophora marina (Lyng.) Kuetz. 37 19-20 Grammatophora islandica Ehr. 37 21 Grammatophora serpentina Ralfs. 37 STRIATELLA 22-23 Striatella unipunctata (Lyng.) Ag. 38 24 Striatella interrupta (Ehr.) Heib. 38 ATTHEYA 25 Attheya decora West 38 [Illustration: PLATE 8] PLATE 9 LICMOPHORA 1-2 Licmophora flabellata (Carm.) Ag. 39