perIderm

[Pref. peri-, and Gr. derma = the skin.] 1. Bot .: One of the four layers of bark, the epiphlœum or phlœum, consisting of several layers of fate, făt, färe, amidst, what, fall, father; we, wět, here, camel, her, there; pine, pit, sire, sir, marine; gō, põt, The American Dictionary and Cyclopedia per i diastole thin-sided, tubular cells, rarely colored green. Mohl draws a distinction between an external and an internal periderm. 2. Zool.: The hard cuticular layer developed by certain of the Hydrozoa. ( Nicholson .)