b - 375 



136. Arista distinctly pubescent; facial ridges bristly on the lower 



five-sixths. Prospherysa. 



Arista bare; facial ridges at most bristly on lower three-fifths (9) . 



Tachina. 



137. Diameter of head at vibrissae as great as at root of antennae. 138 

 Head much shorter at vibrissae than at base of antennae. 139 



138. Facial ridges bristly on at least the lower two-thirds. 



Tachinopsis. 

 Facial ridges bristly on less than the lowest third (93) . 



Demotions. 



139. Lower front corner of third antennal joint produced tooth-like (5). 



Acemyia. 

 Lower front corner not so produced (1) . . . Masicera. 



140. Vibrissae on a level with oral margin 141 



Vibrissae disiinctly above the oral margin. . . . 161 



141. First vein wholly or partly bristly. ..... 142 



First vein bare. ......... 143 



142. Apical cell open (83). . . Chsetoplagla. 

 Apical cell closed and long petiolate (4O, 41) . Metachaeta. 



143. Eyes distinctly hairy. ....... 144 



Eyes bare, or with short, indistinct hairs. . . . 146 



144. Sides of face without macrochaetae. . . . Winthemia. 

 Sides of face with macrochaetae, at least near lower end of eye. 145 



145. Third joint of antennae at least five times the length of the second. 



Paradidyma. 

 Third joint scarcely as long as the second (1O5) . Muscopteryx. 



146. Apical cell closed. . . 147 

 Apical cell open; if closed, the petiole less than one-fifth the 



length of the hind cross- vein. , 149 



147. Frontals not, or scarcely descending below base of antennae. 148 

 Frontal descending considerably below base of antennae. 



Phorichaeta. 



148. Proboscis two and one-half times the height of the head. 



Trochilodes. 

 Proboscis short, not longer than height of head. Miltogramma. 



149. Facial ridges bristly on at least the lower half. . " Araba. 

 Facial ridges bristly on less than low^er half. . . . 150 



150. Antennae reaching only slightly below middle of face. . 151 

 Antennae reaching to or below lowest fourth. . . . 153 



151. Apical cell open. .... 152 

 Apical cell closed, the petiole as long as the anterior cross-vein. 



Euthyprosopa . 



152. Hind tibiae fringed externally with bristles of equal length. 



Thysanomyia. 

 Bristles of hind tibiii of unequal length. . Brachycoma. 



153. Face with macrochaetae, at least near lower end of eye. . 154 

 Sides of face without macrochaetae. . . . . . 160 



