FAMILY ASILID.i: THE ASSASSIN FLIES 175 



37. Antennas without distinct style 38 



Antennae with the style short and broad, two-segmented, easily dis- 

 tinguishable (9, 73, 92) JLaphystia Lcew 



38. Anterior femora on the basal half of the under side with a large patch 



of dense, very short bristles Sphageus Lcew 



Anterior femora without such bristles 39 



39. Third antennal segment very much longer than the basal two combined 



(40, 124) Di/onias Lcew 



Third antennal segment not or scarcely longer than the basal two 

 combined, elongate oval, swollen (8, 34, 79) *Psilocurus Lcew 



40. Antennal style as broad as the third antennal segment and simulating 



a segment, sometimes closely appressed and not easily differentiated. 41 

 Antennal style narrower than the third segment or absent 44 



41. Lateral slopes of the metanotum bare 42 



Lateral slopes of the metanotum with pile (75, 91) Dicoloiius Lcew 



42. Face bare except below 43 



Face haired between mystax and antennae (103) . . . .Ceraturgopsis Johnson 



43. Posterior femora with very short, stout bi'istles below on the apical 



half ( 85 ) Ecthodopa Lcew 



Posterior femora without short, stout bristles below, but with short, 

 erect pile on the whole length (12, 74, 90) fDioctria Meigen 



44. Front narrowed posteriorly 45 



Front not narrowed posteriorly 46 



45. Ocelli situated far forward on the front (56, 133) Plesioma Macquart 



Ocelli situated near the vertex Dolichodes Macquart 



46. Face bare except on the oral margin (cf. Holcocephala) 47 



Face with hair between the mystax and antennae, or evenly haired. ... 49 



47. Third antennal segment swollen, about twice as wide as the second. 



Willistonina Back 

 Third antennal segment elongate, more or less tapering from the base 

 or only slightly wider than the second 48 



48. Third antennal segment elongate, longer than the basal two combined 



(49) Neopogon Bezzi 



Third antennal segment oval, not as long as the basal two combined. 



Lissoteles Bezzi 



49. Head very wide, the face with a deep, transverse groove above the oral 



margin and with only two to six hairs above the mystax (36, 141). 



Holcocephala Jaennicke 

 Head narrower, the face without the transverse depression 50 



50. Mesonotum with the dorsocentral bristles strong and extending in front 



of the suture, if rather weak anteriorly there are no acrostical 



hairs 51 



Dorsocentrals absent or not strongly differentiated; mesonotum hairy, 

 the acrostical hair always present 52 



* Curran, 1931, Amer. Mus. Novit. No. 487, p. 8. 

 t Melander, 1923, Psyche, xxx, p. 212. 



