ep1phragm (g silent), ep1phragma

[Gr. epiphragm a =a covering, a lid; epiphru o to block up: epi =upon, and phra ō to enclose, to fence.] 1. Zool .: A layer of hardened mucus, sometimes strengthened with carbonate of lime, closing the aperture of the shell of land snails during hyber nation. 2. Bot .: A membrane, often divided into teeth, which are always a multiple of four, closing the aperture of the theca in a mo . It is called also the Tympanum (q. v.).