1 Monograi)h o/ Egyptian Diplcra. 



MUSCID^ 



HOLOMETOPA 



ACALYPTER^ 



Trypaneidae 



GENERAL CHARACTERS OF THE FAMILY 



H E AD 



The chaetotaxy of the head and thorax is one of the most im- 

 {xn-tant eharacters in this family, especially the position of th.- 

 bristles, their number and form. 



Head narrower than the thorax, broatl or narrow, widened 

 lielow or not ; the proportions between the breadth, height and 

 depth is often important in distinguishing the gênera. Frons with- 

 out any distinct vibrissae and bearing a row of bristles on its hiteral 

 borders kiiown as the fronto-orhitnl hiistles {or). Thèse are 

 variable in number and form and are divided into superior fronto- 

 orhitah {s. or.), consisting of 1 or 2 pairs bent backwards and 

 iuferior fronto-orhit<tl.'< (i.or.) consisting of from 1 to 4 p.airs bent 

 forwards or outwards. 



Face nsually flattened, sometimes concave (ir somewhat swol- 

 len in the middle, retreating below or not, more or less elongated 

 and sometimes with antennal furrows. 



Epistoma prominent or not. 



Cheeks (genae) broad or narrow, usually bearing 1 bristle, 

 laiown as the (/erial bristir. which when présent is more or less 

 developed . 



Occiput sometimes swollen l)elow and almost always with a 

 row of bristles. known as the occipital row (ocp.) running from the 

 vertex along the posterior orbits to the chin; this ocp. is considered 

 of great systematic value as it may be formed either by black, thin, 

 })ointed bristles or by whitish, thick, truncated bristles. 



Vertex nearly always possessing three pairs of bristles, two of 

 which near the latéral margins known as the vertical bristles (vt.), 

 the inner pair being very long, the outer shorter and the third pair 



