240 DIPTERA OF NORTH AMERICA. [PART IV. 



they are filiform or subfiliform, and vary in length in different 

 species ; in some, they are longer than the body, in others about 

 half the length of the body ; again in others shorter than the 

 thorax. The antenna? of the female are always shorter than 

 those of the male, apparently likewise 6-jointed ; the last joint, 

 however, shows transverse divisions, which have often the 

 appearance of three, four, or five additional joints. 1 The an- 

 tennaa of both sexes are pubescent, but without verticillate hairs. 

 The head is closely applied to the short collare, which receives it 

 in a kind of excavation; this character, distinctly apparent in 

 the only North American species, is also common to all the 

 European ones (Loew, 1. c). Thoracic suture deeply marked. 

 Feet more or less long and stout, spurs of the tibia? and empodia 

 distinct ; ungues usually smooth. (The European A. longipes 

 has, according to Loew, a distinct and rather strong tooth on the 

 under side of the ungues of the hindmost feet ; this is probably 

 the angular projection of the stout basal portion of the ungues, 

 which occurs also in Eriocera and looks like a tooth, although it 

 is quite distinct from the teeth on the ungues of the Limnobina.) 

 The wings of the North American A. megacera are much shorter 

 and narrower in the male than in the female ; but this does not 

 seem to be the case with the European species (Mr. Loew often 

 mentions the wings of the female as being like those of the male). 

 The venation of A. megacera (Tab. II, fig. 12) shows the follow- 

 ing characters : the auxiliary vein ends in the costa nearly oppo- 



1 Hence the disagreement between authors as to the number of the an- 

 tennal joints of the female. Westwood (in the explanation of Tab. XXVI 

 of Walker's Ins. Brit. Diptera) calls the antennae of a female Anisomera 

 10-jointed ; this would be in conformity with the antennae of the females 

 of Eriocera and Penthoptera, upon which I have counted ten joints on living 

 specimens. The only fresh female specimen of A. megacera, which I have 

 had the opportunity to examine, had several subdivisions of the last joint, 

 but they were not sufficiently distinct to be counted ; a dry specimen shows 

 three such subdivisions ; a dry European specimen which I have before 

 me (perhaps Peronecera?), shows four or five. Mr. Loew, in his article, 

 Ueber die bisher beschriebenen europ'aischen Anisomera-Avten (in the Zeit- 

 schriftfur die gesammten Naturwissenschaften, Nov. 1865), calls the antennae 

 six-jointed in both sexes, sometimes with a more or less developed seventh 

 joint ; the latter species, according to this author, belong to the number of 

 those which have short antennae in the male sex. I will have frequent 

 opportunities to quote Mr. Loew's article, and give therefore its title in full.. 



