T. D. A. Cockerell — Descriptions of Tertiary Insects. 309 



Akt. XXXIII. — Descriptions of Tertiary Insects; by 

 T. D. A. Cockerell. 



Part III. [Continued from p. 232.] 

 (8) Fossil Diptera of the Family Nemestrinidw. 



The Nernestrinidse constitute a small but exceedingly inter- 

 esting family of brachycerous Diptera ; called by Comstock 

 the tangle-veined flies. (The spelling Nemistrinidae, in Com- 

 stock's Manual, is a mistake.) Among the Brachycera they 

 appear to have certain primitive characters : palpi (always ?) 

 3-jointed ; antennae with a jointed terminal appendage ; wings 

 with comparatively simple and direct veins. The last state- 

 ment seems at variance with that of Sharp, who says, " the 

 wing nervuration is perhaps the most complex found in the 

 Diptera, there being numerous cells at the tip, almost after the 

 fashion of JSTeuroptera." The apical reticulation of the wings, 

 such as is described in the South African Megistorhynclius , does 

 not occur in the fossil species examined by me, and may be 

 supposed to be secondary to the venation proper, though per- 

 haps suggestive of an ancestral character. Comparison is sug- 

 gested with the Blepharoceridae. 



That the ]N"emestrinids are actually of great antiquity is 

 shown by the remarkable fossil jProhirmoneura jurassica 

 Handlirsch.* This insect was found in the Jurassic rocks 

 of Bavaria, and if Handlirsch's interpretation of the vena- 

 tion is correct, it seems to suggest that Comstock's nomen- 

 clature of the veins in modern forms may need amendment. 

 It is with hesitation that I base an argument on this little- 

 known fossil; but in any event the discussion may serve to 

 illuminate the readily visible characters of the later remains 

 from the Miocene. 



The figure of Prohirnioneura exhibits the following 

 characters : 



(1) A strong subcostal vein, extending nearly to the end of 

 the wing, where it bends upwards and joins the costa. 



(2) A radius, arising from the subcosta very near its base, 

 running nearly parallel with it, but ending near the tip of the 

 wing, not curving upwards at its apex. 



(3) A radial sector, or second radius, parallel with and close 

 to the radius, and not confluent with it basally, — but this last 

 character may be considered doubtful. 



(4) A media, branching in the apical field, and connected 

 with the radial sector by two cross-veins, the first directed ob- 

 liquely inwards, the other in the reverse direction. 



(5) A cubitus, arising from the media not far from the base, 

 and branching near the middle of the wing, the branches run- 



*Die Fossilen Insekten, Part IV, 1906, p. 633, pi. li, figs. 11, 12] 



