102 LEPTID-ffi. 



most about one and a half times. In LeptievE the discal cell is 

 distinctly oblong and always more than twice as long as wide. 

 The only two genera about which doubt might arise would be 

 Xylophagus and Xylomyia.* The TABANLDiE, though possessing 

 the same venation as the LeptibvE, may at once be recognized 

 by the characteristic antenna? and their more robust structure 

 throughout. 



Table of Subfamilies. 



1. Third antennal joint flagelliform, more or less 



elongate, annulated, without arista 2. 



Third antennal joint not flagelliform, short, or 

 but little elongated, rounded, conical, or 

 reniforru, never distinctly annulated ; arista 

 always present 4. 



2. All tibiae with spurs 3. 



Front tibia? without spurs Arthroceratinvr. 



3. The 5th posterior cell in broad contact with 



discal cell ; face with rounded socketed 

 epistoma, margined by broad side-cheeks ; 

 eyes in S contiguous ; scutellum with two 



short blunt spines CraNOMYixiE. 



The 5th posterior cell not touching discal cell ; 

 face flat, epistoma not socketed or margined 

 by broad side-cheeks ; eyes in $ well sepa- 

 rated; scutellum unarmed XYLOPHAGiNiE. 



4. Eyes in c? wide apart ; 3rd vein widely forked 



at much beyond half its length ; face not at 



all socketed Vermileonin^.:. 



Eyes in $ contiguous ; 3rd vein less widely 

 forked before, or at latest at, half its length ; 

 face with rounded socketed epistoma Leptinje. 



In few families of Diptera is there such diversity of opinion 

 with regard to the subfamilies as in the present one. Prof. Kertesz, 

 in his ' Catalogue of Diptera,' admits none at all, but ranks 

 XYLOPHAGiDiE (including Xylomyia and Ccetomyid.e) as separate 

 families. Verrall recognises the four last subfamilies presented 

 here with ChrysopiliNjE as a fifth ; "Williston divides the Leptid.e 

 into three (dealing with North-American species only), Xylo- 

 PHAGiNiE (iucluding Coenomyia), Arthroceratinje (including 

 Xylomyia), and Lepthst^e. Beling has shown the affinity between 

 Coenomyia and Xylophagus in their larval stages. 



Verrall divides the Xylophagiiue and Vermileonin^e, taken 

 together, from the CansroMYiN.E and Leptpn/E (with Chrysopilin.p 

 as an additional subfamily), taken together, by the characters of 

 the face, afterwards distinguishing those of each group from one 

 another by antennal characters ; but the system herein presented 

 is adopted on account of less indecision being likely to arise as to 

 the nature of the antenna? than the degree of prominence of the 

 face 



The Arthroceratin^ as a subfamily are rather difficult for me 

 to judge personally, since no example is available for actual 



* See XYLOPHAGiNiE (p. 104) and Xylomyia (p. 96) respectively. 



