152 
CICADA. 
lias justly claimed the attention of the most cele- 
brated investigators. Reaumur and Roesel in par- 
ticular have endeavoured to ascertain the nature 
of the mechanism by which the noise is produced, 
and have found that it proceeds from a pair of 
concave membranes, seated on each side the first 
joints of the abdomen: the large concavities of the 
•abdomen, immediately under the two broad la- 
mellae in the male insect, are also faced by a thin, 
pellucid, iridescent membrane, serving to increase 
and reverberate the sound, and a strong muscular 
apparatus is exerted for the purpose of moving 
the necessary organs. 
The Cicada ple'oeju is thus distinguished by 
Linn^us as a species*, viz. Cicada with the tip 
of tiie scutellum bidentated, and the upper wings 
marked with four anastomoses and six ferruginous 
lines. 
In this division of the genus Cicada are several 
large and elegant insects, as the Cicada hcematodesy 
distinguished by its body of a polished black 
'Colour, with the divisions of the abdomen marked 
by so many scarlet rings or bands, and the Cicada 
atrata, which is of a fine black, varied beneath 
with yellow streaks in the direction of the abdo- 
minal and thoracic divisions: the wings are black 
to some distance from the base. In this tribe 
also ranks the Cicada vhddis, a large species, na- 
* It is to be observed however that from a great general 
similarity between the Cicadae of this division or tribe, it is diffi- 
cult to form specific characters sufficiently distinctive; and it 
may be doubted whether the present be so. 
