EXTERNAL ANATOMY OF INSECTS. 655 
posterior channel, receiving a corresponding cavity and 
protuberance of the clavicle. With regard to the mid- 
leg, in Copris, the coxa is emboxed in a nearly longitu- 
dinal cavity of the medipectus; and the coxa of the hind- 
leg anteriorly is suspended to a transverse cavity of the 
postpectus, but posteriorly it is received by a cavity of 
the first segment of the abdomen; so that it may be re- 
garded as suspended anteriorly, and inosculating pos- 
teriorly. 
In some tribes of this Order, as the Weevils and Ca- 
pricorns, the coxee of the four anterior legs are subglo- 
bose* and extremely lubricous, and are received each 
by a socket that fits it, and is equally lubricous. In the 
bottom of this externally, and in the head of the coxa, 
is an orifice for the transmission of muscles, nerves, and 
bronchize; but the coxa is suspended by ligament in the 
socket. This structure approaches as near the ball and 
socket as the nature of the insect skeleton will permit ; 
the high polish of the articulations acts the part of sy- 
novia, and the motion is in some degree rotatory or ver- 
satile, whereas in Copris, &c., lately mentioned, it seems 
to be more limited, and is probably, at least in the mid- 
and hind-legs, only in two directions; in the middle pair, 
probably, from the core being in a position parallel with 
the breast, opposite to that of the hind pair. In the 
ground and water beetles (Hutrechina and Eunechina), 
and some other beetles, the coxe, especially the posterior 
pair, appear to be fixed and incapable of motion. In 
many insects these coxee seem to belong as much to the 
abdomen as to the trunk. We have just seen this to be 
* Prate XXVII. Fie. 18, 19. 
