protremata

from The Century Dictionary.

• In Beecher's classification of the Brachiopoda, an order of articulated genera having the pedicle-opening restricted to the ventral valve throughout life and the prodeltidium originating on the dorsal side of the body-wall in the Cephalata stage and later ankylosed to the ventral shell, thus initiating the deltidium, which persists in all later growth stages. The brachia are unsupported by a calcareous ribbon. A few genera (Thecidea, Lacazella) still exist, but most of the genera of the order are extinct.