3-4 Licmophora lyngbyei Kuetz. 40 5 Licmophora ehrenbergii (Kuetz.) Grun. 40 6-7 Licmophora paradoxa (Lyng.) Ag. 39 8-9 Licmophora ovulum Mer. 39 10 Licmophora baileyi (Edw.) Grun. 40 11 Licmophora gracilis (Ehr.) Grun. 39 12-13 Licmophora gracilis var. elongata (Kuetz.) De Toni 39 14-15 Licmophora tincta (Ag.) Grun. 40 [Illustration: PLATE 9] PLATE 10 MERIDION 1-2-3 Meridion circulare (Grev.) Ag. 40 DIATOMA 4 Diatoma vulgare var. grande (Wm. Sm.) Grun. 42 5-6 Diatoma anceps (Ehr.) Kirchn. 42 7-8 Diatoma hiemale (Lyng.) Heib. 42 9-10 Diatoma vulgare Bory. 42 PLAGIOGRAMMA 11 Plagiogramma tessellatum Grev. 43 12 Plagiogramma obesum Grev. 43 13 Plagiogramma pygmæum Grev. 43 14 Plagiogramma wallichianum Grev. 43 EUNOTOGRAMMA 15 Eunotogramma læve Grun. 33 OPEPHORA 16-19 Opephora schwartzii (Grun.) Petit. 43 17 Opephora pinnata var. lanceolata n. var. 44 18 Opephora pacifica (Grun.) Petit. 43 FRAGILARIA 20-21 Fragilaria virescens Ralfs. 44 22-23 Fragilaria arctica Grun. 44 24-25-27-28-29 Fragilaria undata Wm. Sm. 44 26 Fragilaria undata Wm. Sm., var.? 44 30 Fragilaria construens (Ehr.) Grun. 45 31 Fragilaria harrisonii (Wm. Sm.) Grun. 45 34 Fragilaria capucina var. mesolepta Rab. 45 35 Fragilaria parasitica (Wm. Sm.) 45 36 Fragilaria sp. ? 45 37 Fragilaria linearis Cstr. 45 RHAPHONEIS 38 Rhaphoneis amphiceros Ehr. 46 39-40 Rhaphoneis amphiceros var. rhombica Grun. 46 41 Rhaphoneis belgica var. intermedia Grun. 46 SYNEDRA 32-33 Synedra radians Kuetz. 49 [Illustration: PLATE 10] PLATE 11 SYNEDRA--Continued 1-5-6 Synedra ulna (Nitzsch) Ehr. Sporangial 47