Auditory organs of a simple type are present in most insects.
Auditory bulla filled with honeycombed bony tissue.
At the fundus are placed the concrement-cells with their conspicuous otoliths (con) and the inconspicuous auditory cells, which are connected with the subumbral nerve - ring.
In connexion with the large size of the ears is the excessive inflation of the auditory bulla of the skull.
The green gland and the structures associated with it in Decapods were at one time regarded as constituting an auditory apparatus.