September— October iSSS.] 



PSrCHE. 



101 



give to the group a family rank, loca- 

 ting it between the asilidac and inidai- 

 dae. 



The simultaneous possession of fonr 

 species, three from Australia and A. 

 haruspex O. S., will, I hope, give 

 some weight to the remarks I woultl 

 iiere oU'er concerning its true syste- 

 matic position. As Osten Sacken very 

 justly remarked in a letter to me, the 

 group is an old one geologically, and 

 within certain limits will show wide 

 structural variation. In - one of the 

 species, both male and female, now be- 

 fore me, there is no indication what- 

 ever of any anterior branch to the 

 third longitudinal vein. The absence 

 of this vein under some circumstances 

 would indicate very great structural 

 differences, but, as Cope has more than 

 once said, generic, or even family 

 characters in transitional forms or iso- 

 lated groups may cease to have even a 

 specific value. Here a well-marked 

 family character among the asilidae^ 

 therevidae and the like, I am satisfied 

 has nothing more than a specific value, 

 if it has even that. The apioceridae is 

 an old, isolated, geological form ; it 

 cannot be allied to the therevidae or 

 asllidae without doing violence to gene- 

 tic relationships. On the other hand, 

 the midaidae^ certainly the neviistri- 

 dae^ and perhaps also, the acroceridae^ 

 are all families undergoing a similar 

 decadence ; all are apparently old geo- 

 logically ; all show remarkable neura- 

 tional variations within narrow limits, 

 and all, except perhaps the acroccridae^ 

 seem to have more than an accidental 



coincidence in their geographical dis- 

 tribution. Numerous forms of nemis- 

 trinidae and midaidae occur both in 

 Australia and South America, as I can 

 state from the examination of speci- 

 mens. I do not wish it to be inferred 

 from the above that apiocera should be 

 looked upon as only an aberrant type 

 of Diidaidae. but rather that the apio- 

 ceridae from their isolated position 

 should be recognized as distinct in the 

 same way that these other families are. 

 In one thing I agree with Osten Sac- 

 ken ; the shortness of the first longi- 

 tudinal vein in therevidae points to a 

 more remote geological divergence. 

 The argument of fleshy labella has lit- 

 tle weight, for in one of the species be- 

 fore me the proboscis is elongate, slen- 

 der, and the labella small. 



My views, then, in brief are : the 

 apioceridae form an isolated group 

 approaching extinction, it is probably 

 most nearly related geologicallv to the 

 fiemistrinidae and midaidae^ next to 

 the a^///^<7^, and less intimately to the 

 therevidae. In consideration of these 

 views it seems to me best to recognize 

 the group as a distinct one under the 

 name of apioceridae. 



One other thing that has impressed 

 me in the examination of a consider- 

 able collection of the South American 

 flies, and a small one from Australia, 

 and that is the points of resemblance 

 that exists between the dipterological 

 faunae of the two continents. This 

 resemblance, too, in some respects, is 

 more than superficial. With only my 

 small collection for comparison I have 



