ORGANS OF HEARING. 1Q1 



discovered the organ of hearing in the cockroach, 

 (Blata Orientalis,) in the form of an opening 

 covered by a membrane, white, interiorly concave, 

 and situated at the base of the antennae ; under it 

 there is a projection from the brain, (the first nerve- 

 knot or ganglion,) which appears to perform the 

 office of an auditory nerve. The membrane 

 was not round, but semicircular, and immediately 

 bordering on the ring in which the antennae are 

 fixed. Under it I found a white horny substance, 

 similar to that which covers the inner crustaceous 

 envelope of the head. The projections of the brain 

 appeared to give off nerves to the antennae on each 

 side ; but I could not determine whether it spread 

 out over the membrane, which I am inclined to 

 consider the organ of hearing, as I could not other- 

 wise conceive of its functions. 



The antennas of butterflies terminate in a clubbed 

 tip, in which there are not muscles for producing 

 motion, as in the body of these organs, but half a 

 liquid substance filling the cavity. In the Alder- 

 man Butterfly, (Ammiralis Atalanta,) I found this 

 substance intermixed with membranous 'matter, 

 resembling in some degree the substance found in 

 the auditory sacs of the frog, the calcareous portions 

 being less than in the latter. I think it exceed- 

 ingly probable that the clubs of the antennae are 

 the seat of the sense of hearing." * 



* See Field Naturalist's Magazine, ii. p. 24. 



