14 13RACnrCEEA. 



The bi'ach^'cerous venation attains its most perfect form perhaps 

 in the Taba.nid.e, and it is elaborated most in the AsilidtE, 

 Nemestrinid.^, Mydaid^, and CYKTioiE (despite the latter 

 family also exhibiting some very simple venational types), being 

 quite eccentric in the last three families, many of the longi- 

 tudinal veins in the hinder part of the wing running more or 

 less parallel to the hind margin ; whilst in certain genera of 

 NEMESTRiMDyE au additional character is the net-like system of 

 verv numerous small cross-veins. An isolated instance of a cell 

 being subdivided by numerous cross-veins occurs in Lifcastris 

 (SvRpniu.Ti;), in which the subcostal cell is so divided. 



After the Brachycera the venation becomes more simplified, 

 and is, speaking broadly, remarkably uniform in type throughout 

 the MusciD.E, in the higher groups of which (Tachinids, Dexiids, 

 Sarcophagids, and Muscinids) the 1st posterior cell is quite or 

 nearly closed by the upturned apical section of the 4th vein, 

 whilst in the Antkomyin.e and the various subfamilies forming 

 the AcALYPTRATA that cell is broadly open, JS'umerous minor 

 differences occur in these groups, but the type of venation 

 remains the same. Passing on to the Pupipara, some genera 

 may be observed to possess peculiar venation, but they need not 

 be discussed here. 



The g(meral form of the body exhibits the \videst diversity. 

 The head may be variously proportioned to the body, perhaps 

 attaining its minimum of size in the Cyrtid.t: and its maximum 

 in PiPUXCULiD.i:, but normally it is approximately of the same 

 width as the thorax and usually juore or less semicircular. The 

 thorax and abdomen both vary greatly in length and breadth in 

 relation to one another, and range from the flattened form in some 

 Stratiomyid-^ to the humped thorax iu mam^ Empid.e and to tlie 

 globular or balloon-like abdomen in most Cyrtid.t, the whole 

 body in many species of the latter family being practically 

 splierical. As regards vestiture, a short pubescence over the 

 greater part of the tliorax and abdomen is common to the vast 

 majority of genera in BR/VCitYCERA, a few restricted groups being 

 for all practical purposes absolutely bare (Scenopinus). The earher 

 families are eremocha^tous — that is, possess no distinct bristles of 

 a chaetotactic nature on the head or thorax ; but such bristles 

 gradually appear in successive families, as witnessed by the apical 

 spurs on the tibia3 in Leptid.^, spicules or stick-like spines on the 

 legs in some Bombyliid.i:, and real bristles and spines in that family, 

 in DoLiciiopoDiD.E, Empim:, and Thereyid.e, culminating in the 

 powerful chaetotactic system in most Asilid.e ; after which these 

 cliaracters gradually diminish or practically disappear (as iu 

 PiPUNCULiD.E and SYRPniDJs), reappearing and attaining probably 

 their greatest development in the order in the Tachini>',e, the 

 highest group of the Muscid^e (s. latiss.). The pubescence, 

 always soft in Stratiomyid^, attains its greatest development 

 perhaps in Bombyliid.ij, Theretid^, and Asilid.e ; and true 



