EXOPEOSOPA. 81 



EXOPEOSOPA 



(sensu stricto). 



Three submarginal cells ; third joint of the antennae in the shape of an elongated, irregular cone, with a more 

 or less long style, separated from the cone by a distinct suture, and ending in a microscopic bristle; a 

 distinct tooth at the base of the ungues ; no pulvilli ; strong posterior legs ; front legs generally as' in 

 Hyperalonia (compare below). 



The length of the antennal style is variable, and usually in an inverse ratio to the 

 length of the third joint itself: E. sima, O. S., has a long third joint with a very short 

 style; E. socia, O. S., on the contrary, has the style twice as long as the rather short 

 third joint. There is a South-European species (E. stupida, Rossi) which, with all the 

 apparent characters of a true Exoprosopa, and even very small, but sharp teeth on the 

 ungues, has no distinct antennal style; the third joint is a long, gradually tapering 

 cone, ending in a microscopic bristle. 



The eyes are but moderately approximate on the vertex, and there is in this respect 

 but little difference between the sexes. 



The face is generally, but not always, conically projecting ; in the group E. rostrifera, 

 E.Jllia, and E. socia it is merely convex. The length of the proboscis is also variable : 

 sometimes it is withdrawn within the oral opening, sometimes it projects beyond it ; it 

 is longer than usual in the above-mentioned group of species (E. rostrifera &c,). The 

 structure of the front legs and tarsi is the same as in Eyperalonia; the tibise are 

 smooth, without spinules ; the tarsi have rather indistinct articulations, and are beset 

 on both sides with numerous short, delicate, erect hairs ; the ungues are small. But 

 there are exceptions to this structure of the front legs : the three above-mentioned 

 species (E. rostrifera &c.) have the front tibiae beset with spinules, and the ungues 

 larger. I also find both characters in the South-European E. algira, Fabr., which, like 

 those species, has a face not conically projecting, but in other respects differs from them. 



The tooth at the base of the ungues is in some cases very small, but in all the 

 specimens examined I have found a sharp projection, and not merely an incrassation. 

 On the front ungues, owing to their smallness, the tooth is difficult to perceive, yet I 

 have distinctly seen it in several species. In the male the front tarsi are more tapering 

 towards the tip than in the female. 



The generalities which I have given above are the results of the examination of the 

 American species accessible to me, of a few European ones, and of the Australian 

 E. marginicollis, Gray, and another species, related to E. adelaidica, Macq. 



1. Exoprosopa caliptera. (Tab. I. fig. 12.) 



Anthrax caliptera, Say, Compl. Wr. ii. p. 62. 

 Exoprosopa caliptera, O. Sacken, Western Dipt. p. 233. 



Hob. Western United States.— Mexico, Northern Sonora {Morrison). 



A single male specimen from Northern Sonora agrees with the descriptions, except 

 biol. CENTB.-AMEB., Dipt., November 1886. m 



