244 
Dr. Kidd on the 
The newly exposed surface of the whole body is covered 
with the same kind of down as that which covered the pre- 
ceding skin ; except in the case of the long bristly hairs of 
the caudal antennae, which apparently are produced after- 
wards. The colour of the body immediately after the cast- 
ing of the skin is yellowish white, and it remains of that 
colour for a few hours : it afterwards gradually darkens. 
The organ of sound. I have very little doubt that the pecu- 
liar sound which is charcteristic of this insect is produced by 
the wings ; for I have observed in several individuals in their 
perfect state, that, when irritated, they will separate their 
upper wings by a brisk motion laterally from each other ; 
and that upon their being suddenly brought back to their 
natural position, a sound is at the same moment produced, 
resembling that which I have heard the insect spontaneously 
produce during the season of summer ; but I could not fix 
the power of producing this sound to either sex exclusively. 
There is a peculiar organ, forming a part of the common 
integuments of the abdomen, and situated between the fourth 
and fifth stigma on each side ; the anterior portion of which 
consists of a tense membrane, like fine parchment, of a semi- 
lunar form ; this organ from its individual character might 
be supposed to contribute towards the production of the 
sound, but it is found in the female as well as in the male ; 
and its supposed use is not justified by the presence of any 
internal mechanism. 
In two or three instances I have perceived the internal and 
upper surface of the second abdominal segment, answering 
to what is generally called the third thoracic segment, fur- 
nished with two oblong concave laminge, terminating in free 
