656 EXTERNAL ANATOMY OF INSECTS. 



what are called the puncta or dinar ia, which distinguish the 

 sides of the protlwrax of many Scarabmda and Geotru- 

 pidcc, form a base for an elevation of the interior surface 

 with which the extremity of the base of the clavicle, 

 which plunges deep into the breast, ginglymates a ; this 

 structure may also be found in other Lamellicorns, as 

 the stag-beetle (Lucanus) and Dynastes, that have not 

 those excavations ; in these last it is an elevated ridge 

 forming a segment of a circle with, it should seem, a pos- 

 terior channel, receiving a corresponding cavity and pro- 

 tuberance of the clavicle. With regard to the mid-leg, 

 in Copris, the coxa is emboxed in a nearly longitudinal 

 cavity of the medipectus , and the coxa of the hind-leg an- 

 teriorly is suspended to a transverse cavity of the post- 

 pectti.% but posteriorly it is received by a cavity of the 

 first segment of the abdomen ; so that it may be regard- 

 ed as suspended anteriorly, and inosculating posteriorly. 

 In some tribes of this Order, as the Weevils [Curculio 

 L.) and Capricorns [Cerambyx\ the coxae of the four an- 

 terior legs are subglobose 5 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 bronchiee; but the coxa is sus- 

 pended by ligament in the socket. This structure ap- 

 proaches as near the ball and socket as the nature of the 

 insect skeleton will permit ; the high polish of the arti- 

 culations acts the part of synovia, and the motion is in 

 some degree rotatory or versatile, whereas in Copris, &c, 

 lately mentioned, it seems to be more limited, and is pro- 



a See above, p, 308. b p IATE XXVII. Fig. 18, 19. 



