FAMILY ASILID.E THE ASSASSIN FLIES 179 



65. First antennal segment less than twice as long as the second; style 



strongly differentiated (42, 110) Atonia Williston 



First antennal segment more than three times as long as the second; 

 style poorly differentiated (82, 145) Bathropsis Hermann 



66. Third antennal segment at least three times as long as the basal two 



combined Aphestia Schiner 



Third antennal segment not more than twice as long as the first two 

 combined 67 



67. Metanotal slopes or callosities bearing pile or short, stout bristles.... 68 

 Metanotal callosities without pile or bristles 73 



68. Mesonotum evenly clothed with dense pile, most of which is yellow, 



some erect and some appressed; no bare areas outside the dorso- 



central area; large species (25, 80) *Bombomima Entlerlein 



Mesonotum without dense hair concealing the ground color 69 



69. Front at least slightly widening above, never narrowed 70 



Front narrowed above (22, 43, 48) fAtomosia Macquart 



70. First antennal segment at least three times as long as the second.... 71 

 First antennal segment not twice as long as the second 72 



71. Seventh abdominal segment elongate (107) Protichisma Hermann 



Seventh abdominal segment short, three or four times as wide as long, 



or apparently absent (44, 77, 146) JCerotainia Schiner 



72. Face strongly gibbous below and with i-ather abundant hair above 



(47) Pilica Curran 



Face weakly gibbous below and with only a row of hairs on either 

 side (72, 144) §Eumecosoma Schiner 



73. Face with a strong swelling occupying the lower half, most prominent 



in the middle 75 



Face very gently convex or concave and most prominent just above 

 the oral margin 74 



74. Scutellum with long marginal bristles; large, elongate species (55). 



Panamasilus Curran 

 Scutellum with extremely short, upturned marginal hair; smaller, 

 robust species (135) Cerotainiops Curran 



75. Proboscis laterally compressed 76 



Proboscis dorsoventrally compressed (46) TIAndrenosoma Rondani 



76. Metasternum with long hairs (26, 45, 61) Lampria Macquart 



Metasternum bare (26) |;Laphria Meigen 



77. Ai'ista pectinate below (27, 60) °Ommatius Wiedemann 



Ai'ista not pectinate 78 



* This name replaces Dasyllis, a strictly South American genus. Unless the presence of 

 metanotal hairs is a valid character the genus does not differ from Laphria. For key see Banks, 

 1917 (Dasyllis) Bull. Brooklyn Ent. Soc. xii, p. 52. 



t Curran, 1930, Amer. Mus. Novit. No. 425, p. 15. 



t Curran, 1930, Amer. Mus. Novit. No. 425, p. 11. 



§ Curran, 1930, Amer. Mus. Novit. No. 425, p. 8. 



Ti Curran, 1931, Amer. Mus. Novit. No. 487, p. 19. 



!I McAtee, 1918. Ohio Journ. Sci., xix, p. i43. 



° Curran, 1928, Amer. Mus. Novit. No. 327. 



