Volucella. 397 



has the basal part and the somewhat long and narrow labella of 

 about equal length. Thorax square or almost so; scutellum yellow 

 to blackish brown, without fringe below the margin. There are noto- 

 pleural, supraalar and postalar bristles and marginal bristles on scutel- 

 lum, and also a transverse row of bristles in front of scutellum; on 

 the mesopleura are bristles at the upper corner. In the pilose species 

 the bristles are less conspicuous and the supraalar bristles, those in 

 front of scutellum and the scutellar bristles quite inconspicuous or 

 wanting. Metapleura with short hairs, Abdomen short and broad, 

 ovate, not longer than thorax and scutellum together, or it is less 

 broad and more elongate. In the male there are four not trans- 

 formed segments. Genitalia of relatively moderate size. In the female 

 abdomen has five visible segments, the rest more or less hidden, the 

 last terminatlng with two small lamellæ. Legs simple, the usual in- 

 curvation on the posterior side of hind tibiæ near apex more or less 

 pronounced; hind metatarsi thickened. The legs haired in the usual 

 way, more or less densely, the hairs on femora generally not long; 

 one species, inanis, is remarkable by having small, spine-like bristles 

 on the posterior side of anterior tibiæ, one ventral on middle tibiæ 

 and numerous around the apex. Glaws and pulvilli well developed; 

 empodium spine-shaped, hairy. Wings with the subcostal cell closed, 

 the subcostal vein distinct from costa quite to its end, the radial vein 

 bending suddenly up at its end, joining the subcostal vein a little 

 before the apex; the marginal cross-veins retracted from the margin, 

 the upper marginal cross-vein angular, its upper part recurrent; the 

 cubital vein bending somewhat upwards after the marginal cross-vein, 

 terminating considerably before the apex; medial cross-vein before the 

 middle of the discali cell; no stigmatical cross-vein; the basal part of 

 the radial vein with bristles; vena spuria slight, especially in the basal 

 part. Alula large. Squamulæ broad, the thoracai broadest; alar 

 squamula with somewhat long, curious, flattened hairs, thoracai squa- 

 mula with long, richly and regularly branched hairs. Plumula well 

 developed, with somewhat long but simple hairs. 



The developmental stages are rather well known ; already Reaumur 

 found the larva {of homhylans) in nests of Bomhus, and Reaumur and 

 De Geer observed V. zonaria and homhylans respectively layi-ng eggs 

 of which larvæ hatched, which they knew as the same found in the 

 Bomhus-uQsis, though Reaumur committed some confusion of the 

 species. Since then the larvæ have often been observed. Kiinckel 

 d'Herculais has in 1875 published an elaborate monograph over the 

 genus (Recherches sur l'organisation et le développement des Volucelles, 

 Paris 1875), in which the metamorphoses and the larvæ of V. zonaria, 



