NOISES OF INSECTS. 399 
lark (‘Sylvza locustella), which preys upon them, makes a 
similar noise. Professor Lichtenstein in the Linnean 
Transactions has called the attention of naturalists to the 
eye-like area in the right wing of the males of this genus*; 
but he seems not to have been aware that De Geer had 
_ noticed it before him as a sexual character; who also, 
with good reason, supposes it to assist these animals in 
the sounds they produce. Speaking of Locusta viridis- 
s¢ma—common with us—he says, ‘‘ In our male grass- 
hoppers, in that part of the right elytrum which is folded 
horizontally over the trunk, there is a round plate made 
of very fine transparent membrane, resembling a little 
mirror or piece of talc, of the tension ofa drum. ‘This 
membrane is surrounded by a strong and prominent ner- _ 
vure, and is concealed under the fold of the left ely- 
trum, which has also several prominent nervures an- 
swering to the margin of the membrane or ocellus. 
There is,” he further remarks, “every reason to be- 
lieve that the brisk movement with which the grass- 
hopper rubs these nervures against each other, produces 
a vibration in the membrane augmenting the sound. 
~The males in question sing continually in the hedges 
and trees during the months of July and August, espe- 
cially towards sun-set and part of the night. When any 
one approaches they immediately cease their song>.” 
The last description of singers that I shall notice 
amongst the Gryllidx, are those that are more com- 
monly denominated grasshoppers (Gryllus, F.). To 
this genus belong the little chirpers that we hear in 
every sunny bank, and which make vocal every heath. 
@ Linn. Trans, wv. 51— > De Geer, iii. 429. 
