186 LIVERPOOL BIOLOGICAL SOCIETY. 
The soft parts within the ear, that is between the outer 
and the inner surfaces of the cup are :— 
G.) A thin epidermis. 
Gi.) A thick layer of nerve-cells, continuous proxi- 
mally with the supra-cesophageal ganglion. 
Gii.) A layer of long thin rod-hke cells, the inner ends 
of which are close to the floor of the cup, i.e. 
the vibrating plate, while their outer ends abut 
upon the nerve-cell layer. 
(iv.) A very large nerve, broader than the ventral cord 
of the abdomen, which arises from the ventral 
part of the supra-cesophageal ganglion at the 
sides of the ‘‘ cesophagus.”’ ‘This nerve 1s inde- 
pendent of the antennary nerve proper and lies 
dorsal to it. On entering the organ it divides 
into layers which lie, one in the middle of the 
nerve-cell layer and one between this layer and 
the bases of the rod-hke bodies. 
(v.) The antennary nerve proper, which simply passes 
through the basal portion of the organ to reach 
the shaft of the antenna. 
This organ is already large in the larva. It arises as an 
infolding of the epidermis around the base of the antenna, 
and all the structures I have described in it are of epider- 
mal origin. The differentiation of the rod-cells from the 
rounded nerve-cells however only occurs in the latter part 
of pupal life. In the female the intolding of the edge of 
the cup is not carried so far as in the male, so that there is 
a considerable space between the infolded margin and the 
floor of the cup. As to the function of this organ—the 
one object of existence of the male is to find and fertilise 
the female. In this he is assisted chiefly by this organ 
which recognises the sound of the female whenever his 
antenne are turned in her direction, and hence he is guided 
