natural history, a genus of pellicular and crystalliform spars, composed of two octangular pyramids, joined base to base, without any intermediate column. Of these some have long pyramids, others short and sharp-pointed ones, and others short and obtuse pointed ones; the two former species being found in the harts-forest, and the last in the mines of Cornwall.

Diodia, in botany, a genus of the tetrandra monogyria clasps. The corolla consists of one funnel-shaped petal; and the capsule has two cells, containing as many seeds. There is but one species, a native of Virginia.