Webster's Revised Unabridged Dictionary · 1913

Mastax

Mastax , noun

[New Latin, from Greek {not transcribed} mouth, jaws.]

(a)
(Zoology) 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)
(Zoology) The lore of a bird.