4 PROCEEDINGS OF THE NATIONAL MUSEUM Vol.. 68 



hypopleural 3 to 4; mesopleural 5 or 6 behind, one at lower front 

 angle; prothoracic 2 (just above front coxae); prosternum bare; 

 postalar declivity bare; postnotum at side below calypter destitute 

 of minute hairs. 



Abdomen narrow and elongate, the basal segment which in most 

 Tachinidae is not visible from above is quite distinct though short 

 (following custom I have ignored this in counting the segments) ; 

 this short segment is without bristles; the first principal segment 

 has a pair of median bristles not near the margin, and on each 

 lateral margin three, one behind the other ; second segment with one 

 median marginal pair and one lateral near hind margin; third seg- 

 ment with marginal row of four, no laterals ; fourth segment with a 

 row of about 8, which are discal in the middle, marginal at the sides 

 (the American are mostly marginal in the middle) ; fifth or first 

 genital segment in male with one pair of small bristles projecting 

 backward. Basal sternite of abdomen overlapping the tergites, the 

 following sternites however concealed; second tergite with a few 

 bristles at hind angles below near median line. 



Male (fig. 1) with the usual posterior (or inner) and anterior (or 

 outer) forceps, the former pale and much less chitinized than the 

 latter. Female with last genital segment forming a theca or cup, 

 open apically, where a small sting protrudes; on each side at tip the 

 chitin is produced into a curved horn or hook, not jointed, no doubt 

 used in holding the host during the insertion of the sting. The 

 structure is almost identical with that of inter^nedia (fig. 25). 



Legs stout, claws and pulvilli elongated in male, not in female. 



Wings narrow; fourth vein with stump at bend, the last section 

 sinuous, joining the third considerably before its apex, petiole of 

 third vein curving forward to join the costa far before apex. Veins 

 bare except a few hairs at base of third. Hind crossvein sinuous, 

 joining fourth vein about last fifth of its penultimate section. 



Our species, like those of Europe, separate into three groups on 

 the bristles of the scutellum ; Pandelle used these characters in 1894, 

 and Coquillett in 1897. Our dosiades has a single pair of scutellars 

 (the posterior laterals of Pandelle), while intermedia and nigra 

 have in addition a small crossed apical pair. Compressa, known 

 from a single female, has in the type only one of the apicals, hence 

 may belong to either of the two groups. All the rest of our species 

 have in addition to the two pairs mentioned a lateral pair near base 

 (anterior lateral of Pandelle). 



Females of our species separate into three groups on the presence 

 or absence of groups of short ventral setules on the abdomen, on a 

 swelling of the segment. G. dosiades and cmnjrressa have such a 

 swelling with spinules on the first principal segment; noma and 



