prostomium

noun

The anterior portion of the head of an annelid worm, situated in front of the mouth.

noun

The region in front of the mouth in the embryos of the Cœlomata; the preorsd part of the head: said chiefly of invertebrates, as mollusks and worms.

noun

That portion of the head of an annelid situated in front of the mouth.

noun

That portion of the head of an annelid situated in front of the mouth.