100 [May. 



any smooth surface i'; visible between the punctures, and the pubes- 

 cence is very dense subauraUis Eossi (gramineus Sm.). 



3 (2) J 5th ventral segment strongly and conspicuously foveate at the 



base ; antennae extremely long. 



$ mesonotum very densely punctured, but the general surface 

 remains visible, the sculpture not being so rugose, and the clothing 

 much less. 



4 (5) c? trochanters of middle legs entirely yellow or red beneath, the 



penultimate antennal joint also pale beneath, and sometimes the 

 apical one ; foliaceous process of the lacinia of the genital arn^ature 

 with its apical margin straight or slighth' rounded. 

 5 tomentose band of Srd abdominal segment broad and entire, 

 occupying the whole apical impression 



.... Jlavipes F. 



5 (4) c? middle trochanters and penultimate antennal joint not thus 



coloured ; process of lacinia emarginate at the apex. 

 5 tomentose band of 3rd segment interrupted, or at least very much 

 narrowed, in the middle tumulorum L. 



6 (1) c? hind tibiae black, at most the tips and base pale. 



$ apical portion — there being no distinct impression— of the basal 

 abdominal segment impunctate, or practically so. 



7 (8) J tarsi black or dark, and the mesonotum shining. 



5 mesonotum shining, the punctures irregular, of unequal size, the 

 abdomen usually conspicuously metallic, and in good specimens with 

 distinct tomentose markings . . smeathmanellus K. 



8 (7) (5 either the tarsi are black and the mesonotum dull, or the former 



are whitish. 

 5 mesonotum dull or scarcely shining, the abdomen black, sometimes 

 with slight metallic tint. 



9 (10) S tarsi black or darlc. 



5 apical expression of 2nd abdominal segment closely and very finely 



rugulose transver?ely under a strong lens, dull or hardly shining ; 



face longer, less rounded at the sides 



.... vion'o F. 

 iO (9) cJ tarsi nearly white. 



5 apical impression of 2ud segment smooth or nearly so and very 



shining; face shorter and wider 



.... leucopns K. 



As sculpture and other minute structural characters are chiefly used 

 for the separation of the species Halictits and ^i^liecodes, it is necessary 

 above all things that the specimens be perfectly clean. Very fine jiins 

 are advisable for the smaller species, and the j)in is best inserted in the 

 middle of the thorax at the suture joining the mesonotum and scutellum, 

 A very strong simple lens is used for describing the characters of all 

 species, whether large or small, foi- the sake of uniformity, a compound 

 microscope being quite unnecessary for seeing any characters liere 

 described, genital or other. 



