HEAD. 



23 



pable of being thrust out through the frontal suture just 

 above the root of the antennae, and which is used by the 

 imago in springing off the cap to the puparium when 

 about to extricate itself. 



Frontal lunule. An oval or crescentic space just above 

 the root of the antennae in cyclorrhaphous flies, bounded 

 by the frontal suture. 



Epistoma or Peristoma. The oral margin and an indefi- 

 nite space immediately contiguous thereto; not often 

 now used. 



Antennal fovea ox groove. A groove or grooves in the 

 middle of the face, as though for the lodgment of the an- 

 tennae, bounded on the sides by the facial ridges. 



Cheeks or 'jowls' . The space back of the face and below 

 the eyes. 



Orbits. The space immediately contiguous to the eyes, 

 sometimes indicated by structural characters, at other 

 times indefinite. It is called facial, frontal, etc., from 

 the position. 



Clypeus. A part of the mouth structure, often visible 

 below the margin of the mouth in front as a more or less 

 visor-shaped piece. 



Fig. 4. Mouthparts of female Tabanus. After Washburn, nip, maxil- 

 lary palpus; m, mandible; mx, maxilla; lb, labium. 



