INTRODUCTION. XXI 



behind the upper and inner corner of the eye, erect, or the 

 inner pair convergent, the outer pair divergent. 



Postvertical, in the middle of the upper part of the occiput, 

 generally small or absent. 



Ocellar, situated close to the ocelli, usually directed for- 

 ward ; often absent. 



Fronto-orbital bristles, placed on each side of the front, near 

 the orbit, immediately below the vertical bristles. There 

 may be one, two or none on each side*. 



Lower fronto-orbital, situated on the lower part of the front, 

 above the antennae, along the orbit, and not quite in line with 

 the fronto-orbital bristles. They are not of frequent occur- 

 rence. 



Vibrissa, a stout bristle situated near the oral margin on 

 each side. Of important use in the classification of the 

 Acalyptratse. 



Facial, a series of bristles on either side of the middle por- 

 tion of the face, above the vibrissse, especially conspicuous 

 among many genera of the Tachinidse, but usually absent in 

 the Acalyptratse. 



THORACIC DORSAL BRISTLES. 



Humeral, one or more bristles inserted on the humeral 

 callus. 



Post-humeral, usually two, inserted immediately above the 

 dorso-pleural suture, between the humeral callus and the root 

 of the wing, on the bottom of the pre-sutural depression. 



Pre-sutural, one or more bristles situated immediately in 

 front of the transverse suture, above the pre-sutural depression. 



Supra-alar, usually three bristles, one on the post-alar cal- 

 lus, one on the alar frenuin and the third in front of the second 

 on the edge of the supra-alar depression. 



Intro-alar, a row of two or three bristles between the supra- 

 alar group and the dorso-central bristles. 



Dorso-central, two or four longitudinal rows on the inner 

 part of the dorsum, sometimes represent by the 



