The view of the frustule when the valve is uppermost. See also
Barber, H.G. and Hayworth, E.Y. (1981). Guide to the Morphology of the Diatom Frustule.
Freshwater Biological Association, 112 pp.
Image Credit: Marina Potapova
Light micrograph of Hippodonta capitata, with a girdle view on the left and valve view on the right.