154 The Rev. Lanspown GuILDING on the Crepitaculum 
projection of the hemelytron which lies above it; and it is by 
. rubbing the one over the other that the loud or shrill sound of 
most orthopterous insects is produced. = 
One species, Locusta camellifolia, whose call (resembling the 
words shock—shock slowly and loudly repeated) may be heard 
in the stillness of the night at the distance of a mile, has often 
astonished the inhabitant of Europe on his arrival in the tropical 
regions. It is hardly possible to contemplate a more extraor- 
dinary scene than one of our valleys by the light of the moon, 
decorated with the shining foliage of waving palms, and lighted 
.up by thousands of luminous Coleoptera, which flit in every 
. direction before our eyes; while the grasshoppers, in company 
`- with the Hyle and Tettigonie, perform their deafening concert. 
In this most interesting species the wing-cases are admirably 
adapted to increase the sound, being deeply concave in the 
male, even the wings are closely pressed by the arched pteri- 
gostia against the walls of the hemelytra, leaving a considerable 
space vacant above the abdomen. 
The other organ to which I wish to call the attention of 
entomologists, (and which was first noticed, I believe, by De 
Geer,) is situated on the anterior tibiæ of both sexes in such of 
the orthopterous insects as possess the crepitaculum or tym- 
panum at the base of the wing-cases. In the Fabrician Locuste 
it consists of two approximate suboval open foramina, gibbous 
at the sides: in his Achetæ, of two opposite oval flattened 
openings, closed by a delicate membrane. In the true Grylli, 
‘whose organ of sound (noticed by Kirby in his Introduction to 
Entomology,’ vol. ii.) is very different in its structure and posi- - 
tion, these openings are wanting. 
I have no means in this distant country of examining the genus 
Pneumora of 'Thunberg, the species of which are remarkable for 
^ the 
