Per″i‐derm (?), n. 1. (Bot.) The outer layer of bark.
2. (Zoöl.) The hard outer covering of hydroids and other marine animals; the perisarc.
Webster's Dictionary 1913
Per″i‐derm (?), n. 1. (Bot.) The outer layer of bark.
2. (Zoöl.) The hard outer covering of hydroids and other marine animals; the perisarc.