464 WESTWOOD ON THE 



metathorax. In Leucospis this part is generally armed with 

 two short spines, and in Pelopcsus spirifex it is of a yellow 

 colour, whilst the rest of the thorax (except the tegulae) is 

 black. In Oxybelus it is armed with two small pale-coloured 

 membranous-like lobes. 



2d, An internal vertical piece, of which the edge only is 

 generally visible, but which in Pepsis is much more distinct. 

 In P. apkalis, Gray, it is differently coloured from the preced- 

 ing and following pieces. In some others it is also equally 

 visible, and longitudinally divided in the centre. Mellinus, 

 Gorytes, and some other allied fossorial genera, appear to 

 have this part developed in its greatest extent, in which it 

 forms what Latreille terms " une sorte de faux ecusson, 

 sillone ou guilloche." In Oxyhelus the centre of its anterior 

 margin is armed with a spine in addition to the lobes mentioned 

 above. Whether, indeed, this "faux ecusson" may not be a 

 portion of the metathoracic scutellum of MacLeay, having only 

 an apparent separation from it, I will not decide. Latreille 

 mentions this as the third segment of the metathorax, in his 

 description of Oxyhelus. This Mr. MacLeay considers as 

 the scutum of the metathorax ; but M. Audouin regards it 

 as composed of two parts, and forming the metathoracic 

 scutellum (external), and postscutellum (internal). Mr. Curtis 

 has described these metathoracic segments as the scutellum. 



3d, A piece generally much exceeding all the other dorsal 

 metathoracic pieces in size, and often striated, bearing on each 

 side near the anterior angles a spiracle. This Mr. MacLeay 

 regards as the scutellum of the metathorax ; but Messrs. 

 Audouin and Latreille (taking into consideration the oblique 

 direction of the segments of the thorax, when viewed laterally, 

 compared with such Coleoptera as Copris, and the existence of 

 the spiracles,) consider this piece as " un hors d'oeuvre," and 

 that the scutellum and postscutellum of MacLeay *' ne sont 

 autre chose que le premier arceau superieur de I'abdomen." 



4th, A short and generally obscure piece, (which supports 

 the funiculus of Kirby,) termed by MacLeay the postscu- 

 tellum of the metathorax. M. Audouin, however, considers 

 this piece, like the former, as abdominal, and that it is not 

 distinct from it. In those Hymenoptera, however, which have 

 the metathoracic portion more extensively developed, we lind, 

 as might naturally be expected, the divisions of these pieces 



