pilid1um

[Lat. pileus =a cap, a hat, and Gr. eidos =appearance, form.] 1. Bot .: An orbicular, hemispherical shield, the outside of which changes to powder. It occurs in such lichens as Calycium. ( De Candolle .) 2. Zool.: The name given by Müller to the larva of Nemertes (q. v.). It is so called from its helmet form.