periostracum [per-ee-os-truh-kuh m] ExamplesWord Origin noun, plural per·i·os·tra·ca [per-ee-os-truh-kuh] /ˌpɛr iˈɒs trə kə/.
- the external, chitinlike covering of the shell of certain mollusks that protects the limy portion from acids.
Origin of periostracum 1830–40; New Latin, equivalent to peri- peri- + ostracum a shell Greek óstrakon. See oyster Related formsper·i·os·tra·cal, adjective Examples from the Web for periostracum Historical Examples of periostracum
The periostracum, or epidermis, is heavy and often velvety or even hairy.
Augusta Foote Arnold
Gray calls it the Periostracum, from the membranous skin covering the bones of quadrupeds.
George Brettingham Sowerby