1920] Seamans: Anatomy of Anthomyia 203 



THE HEAD. 



The outline of the head when viewed from the front (Figs. 

 1 and 2) is nearly circular, being slightly wider than high, and 

 less regular in the female than in the male. Viewed in profile 

 the outlines differ greatly in the two sexes. In the female 

 (Fig. 3) the line from the vertex to the base of the antennae is 

 almost at right angles to the line from the vertex to the occipital 

 foramen. The face is almost perpendicular, having a slight 

 tendency to be retreating. The antennae are situated distinctly 

 above the middle and are about one-third as long as the major 

 axis of the head. In the male head (Fig. 4) the vertical angle is 

 decidedly acute, the antennae are situated at about half way 

 down from the vertex, the face is retreating, making the 

 epistome appear to protrude, and the minor axis is only two- 

 thirds the length of the major axis. The posterior aspect of the 

 head is essentially the same in both sexes, showing distinct 

 sclerites and sutures, while the anterior portion shows regions 

 which are variable in the two sexes. There are five sutures 

 arising from points on the occipital foramen (Fig. 7). Two of 

 these arise from the two dorsal angles of the foramen, two from 

 the two ventral angles, and one from the middle of the dorsal 

 margin. The two sutures arising from the dorsal angles of the 

 foramen are the paracephalic sutures of Lowne (prsu). These 

 extend upward to the vertex and then around the compound 

 eyes. The two lateral halves of the head thus formed are the 

 paracepala (pre) (Fig. 7). 



The suture which arises from the middle of the dorsal margin 

 of the occipital foramen extends about one-third the distance 

 towards the vertex and forks, each fork disappearing in a faint, 

 almost indistinguishable suture which turns downward at an 

 acute angle to meet the foramen at the base of the paracephalic 

 sutures. The two triangular areas thus formed are the epi- 

 occipital sclerites of Lowne (epos). The space between the 

 paracephalic sutures and above the epioccipital sclerites is the 

 epicephalon (epc). 



The two sutures which start from the ventral angles of the 

 foramen are the basal sutures (bsu). These extend downward, 

 meeting a fold just above the oral margin, and become indis- 

 tinct. The somewhat irregular six-sided area cut off from the 

 paracephala by these sutures is the metacephalon (mtc). The 



