Key To Genera

1 a. Generally two setae per valve, one at each end of the apical axis

Chaetoceros, p. 189

lb. More than two setae per valve, regularly arranged around its margin . . Bacteriastrum, p. 186

Genus Bacteriastrum Shadbolt 1854 (Plate 37, Table 45) Lectotype: Bacteriastrum furcatum Shadbolt (vide Boyer, 1927, p. 114). Synonym: Bacteriastrum varians Lauder.

References: Shadbolt, 1854, p. 14, Plate 1, Fig. 1; Lauder, 1864a, p. 8, Plate 3, Figs. 1-6; Cleve, 1897a, p. 19, Plate 1, Fig. 19; Ikari, 1927; Pavillard,

PLATE 37 Bacteriastrum elongatum: (a) part of chain in girdle view. After Cupp (1943). Bacteriastrum comosum: chain in girdle view. After Cupp (1943). Bacteriastrum hylinum: (a) terminal parts of chain, girdle view; (b) terminal valve with central process. After Cupp (1943). Bacteriastrum delicatulum: (a) part of chain in girdle view; (b) intercalary valve in valve view. After Cupp (1943). Bacteriastrum furcatum: (a) terminal parts of chain in girdle view; (b and d) terminal, and (c and e) intercalary valves in valve view. After Hustedt (1930). Scale bars = 20 ftm.

B. delicalulum

Species

Per valvar axis (|im)

Diameter (jim)

No. of inner setae per valve

B. comosum

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