terminal segments of Aculeate Hymenoptera. 261 



towards the extremity, which is rounded and dilated 

 (see fig, 13) ; armature short and stout, stipites with the 

 apices rounded, and a distinct bkmt spine (lacinia), pro- 

 jecting from beneath, beyond them (fig. 13). 



Halictoides. —lih. ventral ahuost exactly as in Sijs- 

 tropha ; 8th with the central process very long and bent 

 upwards, dilated and thickened at the apex ; armature 

 with the stipites densely pubescent externally. 



Rhophitoides. — In the form of the 8th segment and 

 genitalia almost identical with the preceding, but, having 

 broken the 7th in the only specimen I have been able to 

 dissect, I cannot record its form. 



Ilhopkites. — 7th ventral segment with two elongate 

 flat testaceous lateral processes, slightly widened at the 

 apex; at the base of each externally is a shorter, small, 

 curved process ; 8th with a very long central process, as 

 in the foregoing genera, densely hairy at the apex ; 

 armature, with the stipites, with a flattened lacinia ; 

 sagittaB widely separated at the base, and converging to 

 the apex (see PL V., figs. 3 — 3fZ). 



Biareolina. — 7th ventral segment simple ; 8th with an 

 elongate central process, truncate at the apex, densely 

 clothed with hairs at the sides and beneath ; armature 

 with the stipites produced at the apex into a semi- 

 circularly dilated lacinia. 



Nomada. — The terminal ventral segments of this 

 genus are most characteristic ; the 7th is simple, and 

 with the 8th is hidden ; the 8th is generally produced in 

 the centre into a long process, which is more or less in- 

 curved at the apex and armed with reflexed spines, vary- 

 ing greatly in number and form according to the species 

 (see PI. VI., VII). In some few species the segment 

 is subtriangular, but still is armed with spines at the 

 apex. The armature is rather quadrate in form, and 

 the stipites largely and deeply emarginate inwardly, 

 densely clothed on their laciniae with long plumose hairs ; 

 the sagittse are narrow and covered with the mem- 

 branous spatha nearly to the apex. Excellent specific 

 distinctions can be obtained from these characters. 



Epeolus. — 7th segment truncate at the apex ; 8th with 

 a short central process, not spinose ; armature with the 

 stipites wide, and with wide lacinise not tufted with hairs; 

 sagittse very wide, united and produced in the centre into 

 a narrow truncate process (see PL VII., figs. 9, 10). 



Biastes.—li\\ and 8th segments hidden, 7th slightly 



