120 THE INTEGUMENTAL SKELETON OF THE IMAGO. 



point the ' vertex.' A vertical line, joining the vertex and the 

 axis of the extended proboscis, may be called the ' major axis ' 

 of the head, and the axis of the body prolonged maybe termed 

 its ' minor axis.' 



The forehead lies between the great eyes. It is broad and 



/ 



3 



FIG. 23. / to j, The Head of the Mature Imago of the Blow-fly ; 6, the Head of 

 Stomoxus calcitrans. /, anterior view of the head of the adult female ; 2, 

 anterior view of the head of the adult male ; 3, lateral view of the head of a 

 semi-mature male ; 4 posterior, and 5, anterior view of the head capsule ; 6, 

 anterior surface of the head capsule of stomoxus : /', pars basilaris ; c, clypeus ; 

 (/, mesofacial ; c, epistome ; f, mesofrontal ; g, gena ; g e, compound eye; 

 /, lateral plate or posterior part of paracephalon ; in, mesocranial plates ; 

 p, parafrontal ; v, vertex and epifrontal plate. 



trapezoidal in the female, and narrow and triangular in the 

 male. In the male the whole head is smaller, and the eyes are 

 more obliquely placed. 



Seen from in front, the head capsule of the mature imago 

 exhibits the following parts : the frons, the face, and the 

 epistome in the middle line ; with the anterior margins of the 

 paracephala and the great, or compound, eyes on either side. 



