NEW AUSTRALIAN BEES. 271 



all over with very minute cross-strife, which are here and there joined 

 by short lines, like the elongate cells in the stem of a plant. 



Hah. Queensland (Gilbert Turner ; Eidg. 5. 91, 706). Allied 

 to H.floralis, Sm., but readily known by the dark colour of the 

 thorax. From H. flindersi and H. murrayi it is readily known 

 by the granular (not coarsely wrinkled) appearance of the area 

 of metathorax. It will be observed that this and the following 

 species of Halictus are named after Australian explorers. 



The genus Halictus is so large, and many of the species are 

 so much alike, that the ordinary methods of description are 

 often unsatisfactory. I find that the use of the compound 

 microscope reveals details of sculpture which are of great assist- 

 ance in defining the species, and it seems that this method of 

 examination should be generally employed. 



The small group of Australian species having metallic (blue 

 or green) colours on the thorax exhibits the following micro- 

 scopical characters : — 



(1.) Sculpture of front. — The front in H. dampieri is minutely 

 tessellate, with very few shallow punctures ; in H. flindersi and 

 H. murrayi it is coarsely striate, but with this important differ- 

 ence, that in flindersi the striae are transverse just below the 

 central ocellus, and just below this is a delta-shaped space 

 without regular striae ; whereas in murrayi the striae run right 

 down from the central ocellus, covering the surface. 



(2.) Sculpture of mesothorax. — In H . dampieri vnmwieXy tessel- 

 late, with very few scattered punctures ; in H. flindersi ? minutely 

 tessellate, with short transverse plicae at the places of insertion 

 of the hairs, becoming more distinct in the <? , which has quite 

 long and very distinct plicae, more or less oblique. In H. murrayi 

 and H. urhanus baudinensis the mesothorax is coarsely micro- 

 scopically tessellate, with numerous distinct punctures super- 

 imposed. For the most part these punctures are about as far 

 apart as the breadth of one, or perhaps a little more distant. 



(3.) Sculpture of second abdominal segment. — In H. dampieri 

 and H. flindersi transversely striatulate, with oblique cross-lines, 

 rather more numerous in the latter. H. flindersi also has some 

 very faint punctures about the middle. 



Halictus flindersi, n. sp. 

 5 . Length 6 mm. or a little more ; head, thorax, and abdomen 

 shining purple-blue, the upper part of the clypeus and the anterior part 

 of the mesothorax peacock-green, and the face in general more or less 

 green ; pubescence white, long, and abundant, the hairs with curled 

 ends, on the under side of the abdomen, but elsewhere only moderately 

 abundant ; apical half of mandibles dark reddish ; anteuua9 dark, the 

 fiagellum dull reddish apically beneath ; mesothorax shining, with the 

 median impressed line distinct ; metathorax truncate, the truncation 

 with a sharp edge, the area strongly longitudinally (antero-posteriorly) 



