HYMENOPTERA 77 



all the other large species in its nearly impunctate metallic abdomen, which bears 

 fasciae of white pubescence. A second group is defined by its parasitic habits, and 

 the clothing of the front tarsi of the ? , the hairs of which have not the regular curved 

 form of the industrial species. The females of all the parasitic species but one have the 

 abdomen ferruginous at least at the base, but in two species the males are black or 

 nearly so. Very closely allied to this group is another, the females of which are 

 industrial, and provided with well-developed curved sweeping hairs on the front 

 tarsi. The face is always long, and the pubescence of the front of the head is very 

 short and inconspicuous. The remaining species form several ill-defined groups, 

 none of which are parasitic, and in all the abdomen is impunctate or nearly so. 

 The front of the head is clothed with more or less long hairs, at least in those 

 which have the face elongate. Several species are distinguished by their small 

 size, narrow form, and the more than usually long dorsal surface of the propodeum. 

 N. crabrotioides is the most striking species of this group. Others are remarkable 

 for the great width of the face across the eyes, e.g. N. laticeps and its allies. 

 Finally there are a number of species closely allied to N. facilis, which comprise the 

 least remarkable species of the genus. The face is not extremely short and wide, nor 

 is the form very narrow ; the dorsal surface of the propodeum is short. These three 

 last-mentioned groups, however, seem to be connected by intermediate forms. 



The specific characters of the (/ are chiefly to be found in the amount of 

 dilatation of the scape of the antennae, the markings of the face (which, however, 

 vary a good deal in some species), and the relative length and width of the head. 

 The eighth ventral segment, which it is necessary to extract for examination, also 

 furnishes very useful characters. If the scape of the antennae be viewed from the 

 front, so that the front edge instead of the flattened surface be examined, it will be 

 seen to be more or less concave beneath. The height and form of the arch so 

 formed often furnishes useful specific distinctions. The females are much more 

 difficult to separate, and in a few cases I see no specific distinction between two 

 species, although the males are quite distinct. The shape of the head and its 

 puncturation in front, the sculpture of the anterior area of the propodeum, the colour of 

 the wings, and of the hairs on the apical segment of the abdomen, as well as the 

 facial and prothoracic markings when present, furnish the most useful characters. 



(i) Nesoprosopis facilis. 



Prosopis facilis, Smith, J. Linn. Soc. xiv. p. 683. 



Prosopis facilis, Blackburn and Cameron, P. Manch. Soc. Vol. xxv. (1885 — 



86), p. 142. (Plate II. fig. i, and fig. 8— 8/^.) 

 Male black, with the clypeus, the plate above it, and an elongate spot on either 

 side adjoining it, flavous ; front tibiae and more or less of the front femora testaceous 



