gnathopodite

from The Century Dictionary.

• noun One of the limbs which in crustaceans and other arthropods are modified into mouth-parts; a mouth-foot, jaw-foot, or foot-jaw; a maxilliped; a gnathite.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Zoöl,) Any leglike appendage of a crustacean, when modified wholly, or in part, to serve as a jaw, esp. one of the maxillipeds.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun zoology Any leg-like appendage of a crustacean that is modified to serve as a jaw.