Source : Webster's Revised Unabridged Dictionary (1913)

Mastax \Mas"tax\, n. [NL., fr. Gr. ? mouth, jaws.] (Zo["o]l.)
   (a) The pharynx of a rotifer. It usually contains four horny
       pieces. The two central ones form the incus, against
       which the mallei, or lateral ones, work so as to crush
       the food.
   (b) The lore of a bird.