The calyptra (fig. 24) is half-cleft (dimidiate) and very hairy.
dimidiate, halved, said of a sessile pileus semi-circular in form and attached by the plane edge directly to the wood.
The stem is wanting, and the cap is shelving, dimidiate, reniform or suborbicular.
dimidiate -us: halved; extending half way around; applied to elytra when they cover only half the abdomen.
dimidiate, halved; as where a leaf or leaflet has only one side developed.
To dimidiate two coats of arms, the dexter half of one shield was conjoined to the sinister half of the other.