second notiee on tlie Apiocerina. 313 



011 liead and thorax; the structure of the scutellum, of tlie male 

 forceps, of the legs and antennae; and also the comparative short- 

 ness of the discal cell. About the palpi of Bhaphiocera I have not 

 been able to say anj^thing in my description, nor is there anything 

 in Coqnillett's paper. 



The only character in which both Apiocera and HhapJiiomidas 

 differ from the Asilidae and resemble the Midaidae lies in the 

 venation. 



I Said (1. c. p. 291) „the only link, as yet missing, in order to 

 complete the transition from the venation of certain forms of Erax 

 to Apiocera^ consists in the position of the first vein issuing from 

 the discal cell. We have no Asilid yet in which this vein ends 

 before the apex of the wing, and no Apiocera in Avhich it ends 

 behind it. And this is the only point in which Apiocera is like 

 the Midaidae." 



The venation of Rhaphiomidas ^ far from bridging over this 

 gap, widens it by approaching still nearer to the Midaidae. In the 

 Asilidae {Erax etc.) the first vein, issuing from the discal cell ends 

 in the margin beyond the apex of the wing; in AjAocera it ends 

 before it; m RliapMomidas not only the first, but also the second 

 vein issuing from the discal cell end before the apex. For this 

 reason in the Asilidae there is only one cell between the second 

 submarginal cell and the posterior margin; in Apiocera there are 

 two, in Rhaphiomidas three. The venation of Rhajyhiomidas, 

 as I described it in the „Western Diptera" is not unlike that of the 

 Midaid Diochlistus mitis^ figured by Gerstaecker in bis Monograph, 

 Tab. I, fig. 1. I have indicated the differences, the principal of them 

 being the much shorter discal cell which is charasteristic of an Asilid 

 and also belongs to Apiocera. The three genera of the Midaidae 

 which, like Rhaphiomidas, have tliree cells between the second 

 marginal cell and the posterior margin {Diochlistus., Mitrodetus 

 and Triclonus) occur in Australia and Chili; all the other Midaidae 

 have, like Apiocera., only two such cells (comp. Gerstäcker, Stett. 

 Ent. Zeit. 1868, p. 8). 



The strengthening of the bind margin of the wing by veins 

 parallel to it implies among Diptera the power of regulating the 

 flight, of hovering or poising. We have instances in the Sj'rphidae, 

 Bombylidae etc., diptera of a very light build. That heavier forms, 

 like the Midaidae and the Apiocerina, are provided with a stronger 

 armature of parallel veins seems natural. We have a similar case 

 in the Cyrtidae Eidonchus and Lasia, whose venation reminds of 

 the Midaidae, although the homologies of the veins are different. 



