periostracum

[ per-ee-os-truh-kuhm ]

noun

, plural per·i·os·tra·ca [per-ee-, os, -tr, uh, -k, uh].

1. the external, chitinlike covering of the shell of certain mollusks that protects the limy portion from acids.

Other Words From

• peri·ostra·cal adjective

Word History and Origins

Origin of periostracum¹

1830–40; < New Latin, equivalent to peri- peri- + ostracum a shell < Greek óstrakon. See oyster

Example Sentences

Gray calls it the Periostracum, from the membranous skin covering the bones of quadrupeds.

From Project Gutenberg

The periostracum, or epidermis, is heavy and often velvety or even hairy.

From Project Gutenberg