180 NATURAL ARRANGEMENT OP INSECTS. 



torial anterior legs, as well as produced prothorax ; Me- 

 gascelis, with its large coxse, and intermediate thighs; and 

 Exeira Shkd., wherein the form of the prothorax passes 

 off into the usual transverse collar. In this last genus, 

 which is from New Holland, we ohserve the only in- 

 stance of a petiolated submarginal cell; a structure found 

 in every one of the families of the fossorial aculeates, 

 but which was not known in this until the description 

 of this insect. It is strange that the Ampulicidce should 

 have been allowed to remain so long incorporated in the 

 midst of the family Sphegida, presenting, as they do, so 

 many distinctive characters. In the first place, the hete- 

 roclite structure of the abdomen, which not only distin- 

 guishes them from the rest, but is also sexual; for in the 

 male it is exceedingly obtuse and rounded, and in the fe- 

 male very acute, and either compressed or conical at its 

 apex; and the second segment of which is the most largely 

 developed, in some genera occupying nearly the whole of 

 the abdomen, and in all with which we are yet acquainted, 

 the segments, after the third, are very small. The majority 

 of these genera also exhibit a remarkably sculptured me- 

 tathorax, armed at its extremity with a couple of spines ; 

 their clypeus is produced generally into a sort of aqui- 

 line nose ; but the most remarkable circumstance in their 

 structure is the pulvillus of the under side of the penul- 

 timate joint of the tarsus, an organisation observable 

 no where else among the aculeated Hymenoptera, ex- 

 cepting in some of the social Vespidce. They are said 

 to prey upon the Blatta, and some one genus of them is 

 found in all quarters of the world : the majority are 

 brilliantly metallic, either blue or green, which is agree- 

 ably contrasted, occasionally, with red femora. Very 

 few, excepting the European Dolichurus, and New Hol- 

 land Conocercus, are black. The next family, iheSphe- 

 cidce, are distinguished by a pedunculated abdomen, 

 which is frequently of great length, and very slender. 

 These insects, like thePompilida, also prey upon spiders 

 and caterpillars. Chlorion is distinguished for its metal- 

 lic colours, as also Pronaus : the latter, which is African, 



