'Periostraca' definitions:
Definition of 'Periostraca'
- Periostracum \Per`i*os"tra*cum\, n.; pl. Periostraca. [NL.,
fr. Gr. peri` around + ? shell of a testacean.] (Zool.)
A chitinous membrane covering the exterior of many shells; --
called also epidermis.
[1913 Webster]
