terminal segments of Aculeate Hymenoptera. 263 



at the sides may be remarked the usual recurrent angles, 

 which are strong and horny ; the segment is concave, 

 membranous posteriorly, and only thickened anteriorly 

 in a ridge running between the lateral supports, if they 

 may be so termed ; in the centre of this thicker portion, 

 on its anterior margin, are two long recurved spines 

 dilated at the apex ; at each side, but at some distance 

 from these central spines, are a number of finer spines 

 with sharply truncate dilated heads ; from these a 

 thickened line runs diagonally on to the disk of the 

 segment, bearing a number of simple spine-like hairs, 

 which appear to be much thickened at the base ; beyond 

 the anterior spines is a subtriangular apical mem- 

 branous production (see PL XIII., fig. 21«). In C. 

 sicula the 6th segment has a strong semicircular ridge 

 dividing the more membranous parts across the disk ; 

 in front of this at each side is a thick fascicle of some- 

 what twisted, flat, ribbon-like hairs, so densely matted 

 together that it is difficult to see one separately ; beneath 

 these, on the ridge running from them on to the concave 

 anterior portion of the segment, are a number of fine 

 simple hairs, on thickened bases ; 7th segment narrow 

 and membranous ; 8th tongue-shaped, with a basal 

 angle at each side ; armature clear testaceous-brown, 

 glabrous, highly polished ; stipites long and narrow, 

 nearly straight, widened at the apex into a broad in- 

 ternal hama ; sagittae straight, widely apart at the base, 

 converging to the apex, with a membrane covering the 

 space between them (see PL XIII., fig. 21). 



Megachile. — Very like Chalicodoma in character ; the 

 6th segment membranous, and bearing hairs or spines of 

 different forms across its centre, its apex sometimes 

 terminating in a wing-like process ; armature with the 

 stipites more or less straight, generally divergent at the 

 apices, which are nearly simple ; no distinct lacinia, but 

 the apex of each stipes in maritima is bifurcate ; stipites 

 very large at the base, and enclosed by a ring-like cardo ; 

 sagittae simple, united by a membrane (see PL IX., 

 figs. 1—7). 



Diphysis serratuke. — The armature of this insect is 

 quite unlike that of Osmia, in or near which genus it has 

 been usually placed : it has almost exactly the same 

 form as that of some of the species of Anthidium, next 

 to which genus I should propose to place it ; the white 

 clypeus of the ^ also favours this view, which is held 



