186 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 105 



37. Antennal segment 3 much longer than segment 2 . P. ocellatus (Gigiio-Tos) 

 Antennal segment 3 not longer than segment 2 38 



38. Wing pattern interrupted by transverse hyaline stripe. 



P. sylvosus (Williston) 

 Wing pattern not interrupted 39 ^ 



39. Large species, 19-23 mm P. grandis (Williston) 



Smaller species, 13-18 mm 40 1 



40. Legs dark P. guianicus (Curran) 



Legs rufous P. floridanus, new species 



41. First posterior cell hyaline 42 ! 



First posterior cell darkened 43 i 



42. Wing pattern distinctly paler anterior to second vein. Cheeks never with { 



any black P. angustifrons (Williston) 1 



Wing pattern not much paler before second vein . . P. discalis (Williston) 1 



43. Front and vertex entirely dark 44 I 



Yellow markings at junction of front and vertex . P. ornatifrons (Krober) ! 



44. Wing pattern diffuse P. obsciiripennis (Williston) « 



Dark of wing distinct from hyaline areas . . P. nigromarginatus (Krober) 1 



45. Front with sharply defined T-shaped pattern 46 i 



Front without sharply defined T-shaped pattern 53 I 



46. Antennal segment 3 much longer than segment 2 . . P. costatus (Fabricius) t 

 Antennal segment 3 not longer than segment 2 47 ' 



47. Antennal segment 3 nearly equal to segment 2, at least three-fourths ... 48 

 Antennal segment 3 much shorter than segment 2, less than two-thirds . . 49 



48. Front nearly filled by T pattern P. pictifrons (Krober) 



Front not nearly filled by T pattern P. gracilior (Krober) 



49. Posterior femur mostly reddish P. nigrimanus (Bigot) 



Posterior femur mostly black 50 



50. Cheeks yellow 51 



Cheeks dark 52 



51. Antennae dark P. peruvianus, new species i 



Antennae rufous P. nitens, new species • 



52. Antennae reddish C. ornatus (Williston) 1 



Antennae dark P. varipes (Krober) I 



53. First posterior cell without dark pattern; except along vena spuria, and some- • 



times at very base 54 I 



First posterior cell with some of dark pattern 56 



54. Antennal segment 3 as long as segment 2 .... P. shannoni, new species 

 Antennal segment 3 much shorter than segment 2 55 



55. Cheeks yellow P. fronto (Williston) 



Cheeks dark P. infuscatus, new species 



56. Cheeks dark 57 



Cheeks yellowish 62 



57. Complete distinct postvertical pollinose stripe 58 



No complete distinct postvertical stripe 60 



58. Thorax and abdomen mostly rufous P. townsendi, new name 



Thorax and abdomen mostly dark 59 



59. Abdomen with golden pollen P. connectens, new species 



Abdomen with grayish yellow pollen P. excisus (Wiedemann) 



60. Reddish species P. rufus (Williston) 



Dark species 61 



61. Pleural stripe connected with humeral spot .... P. antennatus (Krober) 

 Pleural stripe not connected with humeral spot . . P. pallifrons (Coquillett) 



