A. J. Grove 
11 
given off from their posterior margins, and follow a course almost 
parallel to the body axis, extending for some distance along the thorax 
before reaching their respective destinations. The nerve from each of 
the second thoracic ganglia travels for some distance in the nuclear 
sheath which surrounds the ganglia themselves before finally entering 
the thoracic cavity. 
Besides supplying nerves to the legs, the thoracic ganglia innervate 
the wing muscles, but as far as my investigations show, these muscles 
receive the whole of their nerve supply from the second thoracic ganglia. 
The nerves which proceed from these ganglia give off a branch which 
passes towards and is lost amongst the wing muscles, but I have been 
unable to discover a similar nerve given off from the nerves from the 
third thoracic ganglia. 
The median abdominal ganglion gives off one large nerve which, as 
in the apterous stage, runs along the mid-ventral line nearly to the end 
of the abdomen where it expands into a small ganglion. 
Sense Organs. 
Consideration of the nervous system naturally leads to the sense 
organs. The only definite sense organs which the winged stage pos¬ 
sesses are the eyes and the antennae. 
The eyes in this stage—as would be expected—are larger in propor¬ 
tion to the size of the head than in the apterous stage. From Plate I, 
Fig. 3, it will be seen that each eye occupies a considerable portion of 
the side of the head, and also that the supplementary eye is much more 
distinct and consists of three small facets. The number of facets in the 
eye is larger, there being on an average about eighty facets in the 
winged stage and sixty in the apterous stage. This enlargement 
accounts for the increased size of the optic ganglia. 
The antennae present many features of interest. As in the case of 
the apterous form, the last or sixth joint has a number of curious ridges 
and markings on it; but where the expanded portion gives place to the 
tapering portion, there are, in the winged stage, several curious tuber¬ 
cles or exci’escences, similar to those which will be described later as 
found upon the third joint of the antennae. At the junction of the fifth 
with the sixth joint, there is another of these curious tubercles. These 
points are illustrated in Plate I, Figs. 5 and 6. Whatever kind of sense 
organ the peculiar ridges on the last joint may represent, it is clear that 
these new structures must be looked upon as satisfying some need which 
