Hypoarion

• (n.) An oval lobe beneath each of the optic lobes in many fishes; one of the inferior lobes.
Found on http://thinkexist.com/dictionary/meaning/hypoarion/

Hypoarion

Hy`po·a'ri·on noun ; plural Hypoaria . [ New Latin , from Greek 'ypo` beneath + ... a little egg.] (Anat.) An oval lobe beneath each of the optic lobes in many fishes; one of the inferior lobes. Owen.
Found on http://www.encyclo.co.uk/webster/H/82
No exact match found