.1 Monograph o/ Eqyptian Diptcra. 



The Medinn (12). hiiul or posterior cross-vein : very important 

 and sitiiated lietween Ml and M3 + Cul, on the posterior part near 

 the hind margin; it may be long or short, oblique or perjjendicular, 

 parallel or not with the radio-median cross-vein, The distance be- 

 tween it and the latter is very important, in relation to the position 

 of the radio-median cross-vein; this distance, following Rondani, 

 can be measured by the relative length of the varions portions into 

 which Ml is divided: thèse portions are : the first or basai, between 

 the base and the radio-median cross-vein; the second or médian, 

 between the radio-median cross-vein and the médian cross-vein; the 

 third or apical, between the médian cross-vein and the apex; or 

 following Bezzi, (which in my opinion is the simplest and best 

 method of the two) by référence to the length of the médian cross- 

 vein. 



Media 3 (13), basai, anterior liasal or discoidal cross-vein (Mo): 

 less important, situated in the middle of the wing near the base, 

 between Ml and M3 + Cnl. 



Cubitus 1 + cubitus 3 (14), anal or ):)osterior basai cross-vein 

 (Cul4-Cn2) : between M3-(^Cul and Cn2 + A2. near the base and 

 below M3 cross-vein : this is very important ; it may be convex or 

 concave or with a very characteristic médian bend (as in Ceratitis): 

 the lower portion of this cross-vein is sometimes very prolonged 

 (as in Dacus). 



The cells are as follows : 



Costal cell (C.) at the fore border and base, between the costa 

 and subcostal vein ; it is divided into two cells by the humerai ci'oss- 

 vein : the Ist costal and 2nd costal cells; the first is not important 

 and not considered hère, but the second may be short or long, broad 

 or narrow. 



Sub-Costal (s.c.) or mediastinal cell : not important, often very 

 small and sometimes indistinct; it is situated below the costal cell, 

 between the sub-costa and RI. The end of this cell however is 

 dilated and forms a callosity known as the Stigma (.st.) or pteros- 

 tigma; this is important in its form, coloration and length as it 

 may be short, long or often very much prolonged; at the base of 

 the stigma where the sub-costal vein should end is situated the pre- 

 viou.sly mentioned costal bristle (c.b.) 



Ri cell (RI), marginal or sub-costal cell : between RI and 

 R2 + 3: mav be narrow or broad. 



R3 cell (R3), sub-marginal or cubital cell : below RI cell and 

 between R2 + 3 and R4 + 5; narrow or broad, more or less widened 

 at the end. 



Radial cell (R), or first basai cell : in the middle of the wing, 

 between R4-f5 and Ml veins and from the base to the radio-median 

 cross-vein; more or less long and widened or not at the end. 



