olfactory pit n.
See nasal pit.
The olfactory pit is the latest formed of the three organs of special sense.
On the ventral aspect of the head, and immediately in front of the mouth, is placed the olfactory pit (fig. 43, ol).
The olfactory pit (ol) is seen a little in front of the eye.
The opening of the olfactory pit does not retain its embryonic characters.