50 PROCEEDINGS OF THE ACADEMY OF [1896. 



57. Larger (4i mm.), face less hairy, lateral face-marks shaped 



like the main-sail of a schooner 66 vagans $ 



Smaller (4 mm.), face more hairy, lateral face-marks tri- 

 angular 59 vespertilio <? 



58. Abdomen with 6 or 8 white marks 59 



Abdomen with yellowish markings 60 



59. Mesothorax shiny ; clypeus dark with a light spot ; face- 



markings white 42 pectidis $ 



Mesothorax dull; clypeus light with dark spots or bars; 

 face-markings yellowish 51 fallax 9 



60. Face-markings white, 1st segment of abdomen largely blue, 



5 interrupta $ 



Face-markings yellowish or yellow 61 



61. Postscutellum yellow 7 mexicanorvm $ 



Postscutellum not yellow H2: 



62. Nervures dark brown, lateral face-marks truncate above, 



clypeus light marked with dark, mesothorax dullish, ab- 

 dominal marks very pale 25 affinis 9 



Nervures colorless, lateral face-marks pointed above, cly- 

 peus dark marked with light, mesothorax shining, ab- 

 dominal marks yellower 10 obscnrata 9 



63. Larger species, length over 6 mm 64 



Smaller species, 6 mm. or less 68' 



64. Males, abdominal bands narrow, inconspicuous, dull yellow, 



emarginate at sides 65 



Females, bands conspicuous 66 



65. Front comparatively shining, flagellum blackish 



69 var. heliantld $ 

 Front dull, flagellum orange 68 verbesiiice $ 



66. Abdomen white with black bands, clypeus white with two 



black dots 64 perpulchra 9 



Abdomen dark with yellow bands 67 



67. Nervures dark 67 sparsa 9 



Nervures colorless 69 albipennis 9 



68. Clypeus hairy, legs black, face-markings and abdominal 



bands white 65 albovittata 9 



Not so 69 



69. Yellow at sides of face extending above level of insertion of 



antennae : size very small 44 mistini $ 



Yellow or whitish at sides of face only extending to level 

 of insertion of antennie ; size not so small 70' 



