Si/s(<'i/ialic Position of the Genus Mycetobin, Mj. 115 



Other Characters. 



As vcgMiils the other cliaractevs — tliose of the tliorax, 

 abdoniL'ii, aiui logs, — not much need he said. Uh>ji)hus is 

 ])cculiar in having hoK)ptic eyes in the male and greatly 

 t'ldarged enipodia ; it does not, however, share either ot" these 

 characters with 0/bio(/(tste}', which resembles the MyCETO- 

 PHiLIDvE rather than liJuipliiis in botii these rcspeets. 



Of the male genitalia, which iisually provide sound indica- 

 tions of relationship, I have made no comparative study ; 

 but it is noteworthy that MijCfioHa appears to be the only 

 ]\Iycetophilid which pos-sesses chitinous spermnthecae in the 

 female. Of tli<'?e. there are two in Mi/celobia, two (or, 

 perhai)S, three) in Olhiogaster^ one in Blii/pfnis. 



Conclusions. 



1. Mycetohia agrees with the RhYPHID^ and diverges 

 from the MycETuPHILID.i: in the possession of a large gular 

 plate, in the stiucture of tlie second palpal joint, in the 

 position of the foi king of the radial vein, the course of tiie 

 cubital vein, and in the chitinous spermatheca3 of the female. 

 Since the venation of Mycetohia has been shown to bo 

 directly derivable from that of the Riiyphid genus Olbiogasler, 

 it is probable that any resemblances in this respect to the 

 MycETOPHILID.E are due to convergent evolution, and not to 

 relationship. The genus Mycetohia (and with it Mcsochn'a, 

 though not Dilontyiaox Symmerus) must theretore, on grounds 

 of adult as well as larval structure, be transferred from the 

 Mycetuphilid^ to the Rhyphidje. 



2. It is at least possible that llie characters of the gular 

 plate and of the position of the radial fork will be found on 

 full investigation to divi.le the Nematocera into two groups, 

 and there is evidence that these grou])S may coincide with 

 those founded on other characters, notably the tracheal system 

 of the larva ; this evidence, therefore, tends to confirm Knab's 

 recent division of the Nematocera (Ann. Ent. Soc. Ainer. 

 vol. viii. p. 9."J, March 191.5) into OligONEUIU, with peri- 

 pneustic larvae, and POLYNEUUA, with amphipuoustic larv?e. 

 The genus Pachyneura seems to require special study, owing 

 to the intermediate character of its venation, and JEupeitenus 

 is also aberrant. 



. 3. If, as seems probable from many considerations, the 

 higher Dipter.i have been derived from the I'OLYNEUKA and 

 the C)LiaONEURA represent aneniirely distinct line ot evolution, 



6* 



