92 MR. smith's catalogue of hymenopteeotjs insects 



every known country of the world, contains individuals exhibiting 

 great variety, not only in their colouring, but also in their struc- 

 ture and form ; one group, which contains the most highly 

 coloured and elegantly formed species, have their tibiae and tarsi 

 destitute, or nearly so, of spines ; another, on the contrary, have 

 their tibiae more or less spined, the anterior tarsi spined, and 

 frequently pectinated; a third group have the intermediate and 

 posterior tibiae furnished with a double row of teeth, or serrations, 

 the tarsi being strongly spined. All the above striking differ- 

 ences are, however, linked together b}^ imperceptible modifica- 

 tions ; these will always be found, when an extensive collection 

 of these insects, from various countries, are brought together and 

 carefully examined. The differences alluded to are undoubtedly 

 of high value, when investigating the oeconomy and habit of the 

 species; thus we find, that the P. ptmctiim of Europe, which 

 belongs to the subgenus Agenia, in which the species are destitute 

 of spines on the tibiae, is not a burrowing insect, but constructs 

 tubular cells of mud ; P. rujlpes, on the contrary, is eminently 

 fossorial and has serrated posterior tibiae, and has also the anterior 

 tarsi furnished with long cilia. In the present paper, I adopt as 

 subgenera, the names given to the groups by Schiodte, in Kroyer's 

 Tidsskrift. 



1. PoMPiLUS LEUcoPHiEUS. P. schistacco-pubescens ; facic albo-ma- 

 culata ; prothoracis margine postica alba ; aUs fuscis basi hyalinis. 



Male. Length 5^ lines. Black, covered with slate-coloured pubescence 

 or pile ; a spot on each side of the clypeus, the inner orbits of the 

 eyes, not reaching their vertex, a narrower line behind them and the 

 palpi, yellowish-white ; the antennae stout and tapering to their apex; 

 the hinder margin of the prothorax white and subangulated ; wings 

 brown, becoming gradually hyaline to their base ; the tibiae and tarsi 

 strongly spinose ; a white spot on the posterior tibiae near their base ; 

 the calcaria nearly as long as the basal joint of the tarsi. Abdomen 

 densely pilose; the apical margins of the three basal segments 

 naked and shining; the four apical segments beneath, naked and 

 shining. 



Hob. Malacca. 



2. PoMPiLus VAGABUNDUS. P. atcr, guttis maculisque flavis varie- 

 gatus ; alis hyalinis apice fuscis ; tibiis posticis ferrugineis. 



Female. Length 5^ lines. Black ; a line on the inner orbits of the eyes ; 

 the anterior margin of the clypeus with a narrow line which unites 

 with a quadrate spot on each side of the clypeus, and a narrow line 

 behind the eyes, yellow ; the face with a thin silvery pile, and the 

 cheeks with a few white hairs. Thorax covered with a fine silky white 



