5 Nitzschia dubia Wm. Sm. 118 6 Nitzschia amphioxys Wm. Sm. 114 7 Nitzschia compressa (Bail.) 116 8 Nitzschia compressa var. minor H. L. Smith 116 9 Surirella intermedia Lewis (zone view) 128 10 Surirella arctissima A. S. forma minor 128 11 Surirella ovalis Bréb. 126 12 Surirella biseriata (Ehr.) Bréb. 124 13 Nitzschia sigma (Kuetz.) Wm. Sm. 121 14 Nitzschia obtusa var. flexella H. L. Smith 121 15 Stauroneis legumen Ehr. 89 16 Nitzschia obtusa Wm. Sm. 121 [Illustration: PLATE 39] PLATE 40 1 Caloneis liber (Wm. Sm.) Cl. 81 2 Anomoeoneis sphærophora (Kuetz.) Cl. 80 3 Nitzschia spathulata Bréb. 120 4 Stauroneis ? abnormal 89 5 Navicula ? abnormal 101 6 Podocystis adriatica Kuetz. 129 7 Nitzschia dissipata (Kuetz.) Grun. 120 8 Cymbella ventricosa Kuetz. (zone view) 62 9 Navicula radiosa Kuetz. (zone view) 94 10 Detail of Rhabdonema arcuatum (Lyng.) Kuetz. 35 11 Diatoma anceps (Ehr.) Kirchn. (containing chromataphores) 42 12 Coscinodiscus asteromphalus Ehr. (trans. section, after Pelletan) 23 13-14-15 Transverse section (diagram) of Pinnularia showing straight, oblique and grooved raphes 101 16 Transverse section (diagram) of Biddulphia favus showing inner punctate stratum (after Deby) 31 17 Transverse (ideal) section of Surirella 124 18-19 Transverse (ideal) section of Pinnularia, before and after division 101 20 Transverse section of Nitzschia linearis (Ag.) Wm. Sm. 122 21 Transverse section (diagram) of Navicula 89 22 Transverse section (diagram) of Cymbella 60 23 Transverse section (diagram) of Amphora 65 [Illustration: PLATE 40] End of the Project Gutenberg EBook of The Diatomaceae of Philadelphia and Vicinity, by Charles Sumner Boyer