284 Mr. W. Weschd on systematic affinities of the Phoridx 



them botli in a sub-family, " Encrgopoda," with the Asihda! 

 and Empidai, placing the group at the end of" the Ortliorra- 

 pha.* Herr. Theo. Becker thinks that they arc derived from 

 Nematocerous forms allied to the Mycetoi^hilidai and 

 notices the structure of the bristles found only in the 

 Phoridfe and ]\Iycetophilida3.'|" 



Schiner in his "Fauna Austrica" placed them between the 

 Bibionidio and the ]>orboi-ida',but whether for convenience, 

 or on account of afhnity is not clear. 



Not one of these authors is sure whether this family 

 belongs to the Orthorrapha or to the Cyclorrapha, and 

 nothing definite seems known about the mechanism of 

 the pupa-case. 



The problem being so difficult of solution. Osten-Sacken 

 even going so far as to say that " a real affinity with I'hora 

 does not exist anywhere," it may seem presumption in me 

 to attempt to solve it, as I certainly have no pretensions 

 to a comprehensive knowledge of exotic species of Diptera. 

 But I am encouraged to present my views, as I attack 

 from a new position, none of these writers with the possible 

 exception of Becker having made much use of the micro- 

 scope, while the great majority of the observations from 

 which my conclusions have been arrived at, are founded 

 on the anatomy and microscopic structure, the minute 

 size of these insects mostly requiring a magnification of 

 250 diameters for a good view of such organs as mouth 

 parts or genitalia. 



After an examination and comparison of a number of 

 preparations, and a study of the genitalia of several species 

 of Phorida), (I was already familiar with the Muscid forms), 

 I came to the conclusion that they have no real affinities 

 either to tlie Borborida' or the Hippoboscida^, tlie families 

 that are placed before and after them in Mr. Verrall's list 

 of British Diptera. Further, tliey are sharply divided from 

 any of the Muscida^ by the absence of the ptilinum, the 

 membrane on the head, which being inflated, is used to 

 push the cover ofi' the pupa-case. The absence of this 

 structure raises a very strong doubt as to whether the 

 Phorida' have any place in the Cyclorrapha; a doubt that 

 in my mind is a certainty that they have not. 



* Tlie position of riiont in tlio svstom of Diptera, " Enl. INfon. 

 Mag." 2iid ser., vol. xiii, pp. 204, Sep" 1902. 



t Die Phorielen. Abli. (1. k. k. Zool-bulan. Ges. Wieii. BJ 1. 

 Heft ]. 



