FIGURES 52–57 in Entogoniopsis gen. nov. and Trilamina gen. nov. (Bacillariophyta): a survey of multipolar pseudocellate diatoms with internal costae, including comments on the genus Sheshukovia Gleser

FIGURES 52–57. Scanning electron micrographs of Entogoniopsis venosa from Joe's River, Barbadoes (Figs 52, 54, 56), and Oamaru, New Zealand (Figs 53, 55, 57). Fig. 52: Oblique external view, central rimoportula indicated by arrow. Fig. 53: Oblique internal view. Note the internal opening of the rimoportula indicated by arrow. Fig. 54: Detail of the specimen in Fig. 52, showing a small depression around the fractured external tube of the rimoportula. Fig. 55: Detail of the specimen in Fig. 53, showing the internal opening of the rimoportula in the form of a slightly raised slit. Note the prominent costae radiating from the rimoportula. Fig. 56: Detail of the specimen in Fig. 52, showing the hyaline marginal ridge, and the mantle, with external thickenings on the part adjacent to the valve face, associated with the internal costae (arrows). Fig. 57: Detail of the specimen in Fig. 53, showing the internal costae and the hyaline mantle margin, with a slight inward expansion.