270 Philippine Journal of Science i^ 9 



species of Halictus are ground-nesting bees of relatively feeble 

 flight, and the wide distribution of several species through the 

 islands of the Archipelago is rather surprising. The smaller 

 species are sometimes referred to as sweat bees, from their 

 habit of settling on the skin, apparently attracted by the per- 

 spiration. Is it perhaps possible that they occasionally attach 

 themselves to birds, and thus get carried about? The follow- 

 ing key should suffice for the separation of the species before me. 

 I include Nesohalictus, as it is likely to be mixed with Halictus. 



Males 1 - 



Females 8. 



1. Clypeus with a yellow or whitish transverse apical band 2. 



Clypeus entirely black . 4. 



2. Tibiae yellow, with dark markings; scape with a light stripe; area 



of metathorax not plicate or only very delicately so near base. 



eschscholtzi sp. nov. 

 Tibiae mainly or wholly dark ~ 3. 



3. Flagellum ferruginous beneath; hind tarsi or, at least, basitarsi yellow. 



philippinensis Ashmead. 

 Flagellum dark or dusky beneath; hind tarsi dark. 



philippinensis nigritarsellus var. nov. 



4. Mesothorax dull or dullish 5. 



Mesothorax shining _ 6. 



5. Larger; stigma pale ferruginous; tarsi light red. 



Nesohalictus robbii Crawford. 

 Smaller; stigma dark brown; tarsi dark melanurops sp. nov. 



6. Head very large ; scape largely red ; anterior knees red.... scapalis sp. nov. 

 Head not unusually large _ 6a. 



6a. Very small species; mesothorax highly polished, without conspicuous 



punctures _ lionotulus sp. nov. 



Small species; mesothorax shining, but finely and distinctly punctured. 



itaminus sp. nov. 

 Larger; mesothorax with evident punctures „ 7. 



7. Mesothorax coarsely punctured; first abdominal segment closely punc- 



tured all over baguionis Crawford. 



Mesothorax polished, more finely punctured; first abdominal segment 

 without evident punctures luzonicus Strand. 



8. Tibiae mainly yellow or reddish yellow; tubercles yellow. 



eschscholtzi sp. nov. 

 Tibiae and tubercles not thus yellow 9. 



9. Mesothorax dull, without evident sculpture 10. 



Mesothorax more or less shining or evidently sculptured 12. 



10. Metathorax dark green (Baguio) opisthochlorus sp. nov. 



Metathorax black, the area granular, without evident sculpture 11. 



11. Apical part of metathoracic area shining and with a median groove 



(Puerto Princesa) caroli sp. nov. 



Apical part of area entirely dull; larger species (Culasi and Mount 

 Maquiling) mcgregori sp. nov. 



