The pineal gland sits in the central portion of the brain and helps secrete hormones, including
melatonin

hm (events in a 24 hour period)

In this picture the probe is pointing straight to the pineal gland after the brain has been cut in half by hemispheres:
pineal_body.jpg

In this picture the brain has not been cut at all and by pulling back the cerebellum the pineal body is visible and labeled:

pineal_gland.jpg