Plate 1. Fig. 1. (Biblarium) constrictus Ehrenberg nom. nud., reproduced from Ehrenberg's manuscript drawings 2268, labelled Bargusina, Siberien (Museum für Naturkunde, Humboldt Universität zu Berlin, Berlin, BHUMP at http://download.naturkundemuseum-berlin.de/ehrenberg/). Fig. 2. Illustrations of peragalli Héribaud, peragalli var. major Héribaud, peragalli var. eximia Héribaud, reproduced from Héribaud (1903), Pl. 10, Fig. 21: peragalli Héribaud; Pl. 10, Fig. 22: peragalli var. major Héribaud; Pl. 10, Fig. 23: peragalli var. eximia Héribaud (1903): 31, Pl. 10, Fig. 23. Fig. 3. Illustrations of javanicus Hustedt, reproduced from Hustedt (1913 in Schmidt: Pl. 294, Figs. 42 and 43). Fig. 4. Illustrations of celatom Okuno, reproduced from Okuno (1958): Text-Fig. 1A E.-
Plate 2. Figs. 1 4. Specimens of constrictus from Slide No. 624 of Tempère and Peragallo, Diatomées du monde entier, second edition (lectotype is slide No. 624, BM 68973). 1 and 2: same specimen (length 70 µm, width 15 µm, at widest point); 3: different specimen, the form of striae suggest that this is possibly a valve from an initial cell (length 75 µm, width 20 µm, at widest point); 4: a third specimen (length 60 µm, width 10 µm, at widest point). Figs. 5, 6. Specimen of javanicus from BM Adams E 216 (isotype, Recent - Sussw. Diatomeen vom Vulkan Pangeron, Kat. VII, No. 3076, 2500 Fuss hoch. Thum, see Thum 1891 [1895: 43]) (length 30 µm, width 10 µm, at widest point). Fig. 7. Specimen of peragalli, from BM 68397 (length 40 µm, width 10 µm, at widest point), (Tempère and Peragallo, Diatomées du monde entier, second edition, No. 51, Joursac, Cantal, isotype material for peragalli, peragalli var. major and peragalli var. eximia). All figures measurements bar = 10 µm.
Plate 3. Figs 1, 2. constrictus. Miocene fossil deposit from Trout Creek Formation, Oregon, USA. Both specimens of smallest size and reduced shape with almost elliptical valves. 1: with rimoportula on valve mantle (arrow) (bar = 6 µm); 2: with valvocopula and a copula in position; these valves are probably formed immediately or near auxospore formation and are indicative of the smallest size range (bar = 10 µm).
Plate 4. Figs. 1 7. peragalli. Miocene fossil deposit from Lovelock, Nevada, USA, ex. Brigger. 1 and 2: whole valves, position of rimoportula indicated by arrow, central sternum notable on each specimen (2) with primary transapical ribs and very few secondary ribs (1 and 2, bar = 25 µm); 3: detail of external view of pole, with more closely packed striae (suggesting a rudimentary pore field) and a scattering of short spines (bar = 6 µm); 4: detail of internal view of pole with prominent rimoportula (bar = 7.5 µm); 5: detail of external pole of pole with prominent rimoportula (bar = 5 µm); 6: detail of first six bands of girdle; note the arrangement of each band relative to the next (all appear open) and the pore field in the face of the ligula (arrows); these bands are primary copulae (the first is, by definition, the valvocopula) (bar = 6 µm); 7: detail of bands further from the valve; note the arrangement of each band relative to the next (all appear open) and the lack of a pore field in the face of the ligula; these bands are secondary copulae (bar = 5 µm).
Plate 5. Figs. 1 5. bradburyii. Miocene fossil deposit from Trout Creek Formation, Oregon, USA. 1: detail of external view of valve with girdle from preceding valve; bands are probably secondary copulae, with one band possibly a pleura (arrowed) (bar = 10 µm); 2: external view of whole valve with visible sternum and striae (bar = 15 µm); inset, light micrograph of valve from holotype slide BM 101326 (Trout Creek, Oregon, USA) (specimen length 30 µm, width 10 µm); 3: detail of first six bands of girdle; note the arrangement of each band relative to the next (all appear open) and the pore field in the face of the ligula (arrows); these bands are primary copulae (the first is, by definition, the valvocopula marked vc, next to valve, marked v) (bar = 6 µm); 4: detail of external view of pole with rimoportula (arrowed) (bar = 5 µm); 5: detail of two adjoining bands from the cingulum, showing septum (marked s) and interconnection (bar = 5 µm).