Hardwicke's science-gossip : an illustrated medium of interchange and gossip for students and lovers of nature . Fig. 151. Navicula firma, var. R(Navicula dilatata, Ehr.) x 400. Fig. 152. Navicula firma,var. y, x 400. Variety a, linear oblong=Navicula Iridis, Ehr. Variety /3, pointed elliptic = Navicula dilatata,Ehr. (fig. 151, outline only). Variety y, cuneate = Navicula amphigomphus,Ehr. (fig. 152, outline only). Variety £, valves turgid elliptical-lanceolate, withseveral marginal longitudinal bnes, large median blank space, striae distinct. This is undoubtedlythe finest of all the varieties
Hardwicke's science-gossip : an illustrated medium of interchange and gossip for students and lovers of nature . Fig. 151. Navicula firma, var. R(Navicula dilatata, Ehr.) x 400. Fig. 152. Navicula firma,var. y, x 400. Variety a, linear oblong=Navicula Iridis, Ehr. Variety /3, pointed elliptic = Navicula dilatata,Ehr. (fig. 151, outline only). Variety y, cuneate = Navicula amphigomphus,Ehr. (fig. 152, outline only). Variety £, valves turgid elliptical-lanceolate, withseveral marginal longitudinal bnes, large median blank space, striae distinct. This is undoubtedlythe finest of all the varieties of Navicula 153, valve. Eig. 153 a, b, ideal sections ofvalve and frustule; a represents a central transversesection, showing thickening of the silex forming theblank median space; b, transverse section of frustulebeyond the median space, and intended to illustratethe contour of the frustule : it will be seen that oneportion of the valve inclines downwards towards themedian line, and the other, or marginal part, formsa broad curve towards the connecting
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Keywords: ., bookcentury1800, booksubjectnaturalhistory, booksubjectscience
