THE SONG OF THE CICADA. 
359 
sensibly differ from the epimera of the other thoracic seg- 
ments. 
At the upper and internal angle of the epimeron of either 
side is to be seen the first joint ( coxa 44 hanche,” P. figs. 1, 2, 3,) 
of the leg of the third pair. It is accompanied by an appendage 
called 64 cheville ” (c, figs. 1, 2), by Reaumur, which is none 
other than the trochanter of the thigh which has taken on a 
great development, and is received, in part, into a slight de- 
pression in the operculum. This arrangement led Reaumur 
to believe that the trochanter acted as a check to prevent the 
operculum from moving too much — an error, as the latter is 
quite immovable. 
2. The first abdominal segment. This may be conveniently 
divided into a peripheral, and a central part. 
a. The peripheral part. This 44 somite ” is narrow behind, 
and forms on its sides the upper border of the frame of the 
drum ( 44 cadre de la timbale ”). This border divides in front 
into two branches, which eventually form two ridges ( 44 aretes” ) 
of a triangular pyramid, termed by M. Carlet the 44 tetrahedron,” 
which has its apex at their point of divergence. There are, more- 
over, four sides, or faces, of which one forms the base of the 
tetrahedron, while that which is bounded by the anterior and 
posterior ridges is pierced for the first stigmatic orifice (s, fig. 1) 
of the abdomen. There are two symmetrical tetrahedra. 
b. The central part, which comprises the entogastrium (Au- 
douin, op. cit. p. 125), or 44 triangle ecailleux ” of Beaumur. M. 
Carlet proposes to retain the first term, as a reminder that the 
part is homologous with the entothorax. The entogastrium 
somewhat resembles a bird with a forked tail and wings spread 
out. A median crest is developed upon the hinder part of its 
body, affording insertion for the motor muscles of the 44 timbales ” 
(fig- !)• 
The second segment of the abdomen is very broad behind and 
on the sides (2a, fig. 2), but becomes much narrower in front (2a, 
fig. 3), clasping by its concavity the preceding somite, with 
which it becomes completely fused in the middle line. This 
arrangement is exactly the reverse of that of the first segment, but 
is to be found only in the male insect. Laterally there will be 
found in the second segment a kind of inclined plane, resting 
upon its upper margin, which M. Carlet terms the floor of the 
cavern ( 44 plancher de la caverne ”), as it forms the lower surface 
of this cavity (C, figs. 2, 3). A large chitinous scale ( 4C apophysis 
of the cavern,” ap, figs. 1, 3), is to be seen at the junction of the 
part just described with the second abdominal ring, which forms 
the outer wall of the cavern. It is triangular, completely 
masking the drum, to see which it must be lifted, and is itself 
in turn covered by the lower (or hinder) wing, when this is at 
