British Hymenoptera. 229 



5. Psithyrus quadricolor, Lep. (PL XII., fig. 2). 



Lep., Ann. Soc. Ent. Fr., i., p. 376 = Barhatelliis, $ , 

 Smith (nee Kirby), Cat. Brit. Hym., 2nd ed., p. 222. 



Black ; thorax with a wide yellow band in front, and some pale 

 hairs posteriorly round the scutellum ; apex of the abdomen in the 

 5 clothed with white hairs, extreme apex of the <? with reddish 

 hairs. 



Very like tlie three preceding, but differing in the 

 following particulars : — 



3' . 2nd and 4th joints of the flagellum of the antennae sub- 

 equal ; 3rd about two-thirds as long as the 4th. Abdomen shorter ; 

 5th segment clothed with black hairs, 6th and 7th with rufescent 

 hairs ; 7th segment beneath simple ; genital armature very 

 different from that of any other species, the lacinia produced into 

 a long, narrow, horny process (see PI. XII., fig. 2). 



5 . Differs from any of the preceding in being smaller, with the 

 abdomen (looked at from above) more rounded; the 7th dorsal 

 segment shining, finely and irregularly punctm-ed ; 6th ventral 

 segment armed at the extreme apex with a reflexed triangular 

 spine or tooth, which projects amongst the dense pubescence which 

 clothes the apex of the segment. Length, 15 — 20 mm. 



Hah. Common in many localities, and generally dis- 

 tributed. Lives with Bomhiis pratorum and Schrimski- 

 ranus. 



BoMBUS, Latr. 

 Latr., Hist. Nat. Ins., xiv., p. 63. 



Wings with three submarginal cells ; labial palpi 4-jointed ; 

 maxillary palpi 2-jointed ; mandibles of ^ fringed with curled 

 hairs ; posterior tibia; outwardly shining, generally with a more or 

 less distinct impression down the centre; J with the posterior 

 tibiae dilated and concave outwardly, very shining, with a fringe of 

 long hairs on each side of the concavity (this arrangement is called 

 the " corbicula") ; (? with six ventral segments exposed ; 7th sub- 

 transparent, shaped much as the 6th ; 8th narrower, somewhat 

 truncate, hairy at the apex; genital armature stout, very variable 

 in form (see PI. XII.). 



A genus of social bees. Communities consisting of 

 males, females, and workers. 



