ORTALIN &. 377 
Group ORTALIN A. 
Front broad, with bristles on the upper part only; vibrissee absent; clypeus usually 
well developed. Abdomen with four or five segments ; 
ovipositor of the female in most of the genera flattened and terminating in a point. 
Wings usually with dark 
markings; auxiliary vein ending obliquely in the costa, seldom approximated to the 
second and third basal cells of moderate 
size, the third sometimes drawn out into a pointed lobe. 
Antenne with dorsal arista. 
Legs of moderate size, sometimes elongate and slender. 
first vein, and therefore less conspicuous ; 
The genera represented in the Mexican collections before me may be tabulated as 
follows :-— 
1. Proboscis not incrassated; clypeus feebly developed ; ovipositor 
not flattened Loe ee Loe 2. 
Proboscis thick ; clypeus well developed; ovipositor flattened . 3. 
2. Front very prominent; third basal cell not longer than the second. Pyrgota, Wied. 
Front not prominent; third basal cell inferiorly drawn out into a 
long point ; ovipositor unusually elongate . Loe ee Toxotrypana, Gerst. 
3. Cheeks inferiorly at least as high as the longitudinal diameter of 
the eyes . Loe Ce 4. 
Cheeks inferiorly more or less developed, but never as high as the 
longitudinal diameter of the eyes. 6. 
. First posterior cell of the wings unusually narrowed towards its 
termination, the last section of the fourth vein being angularly 
bent towards the tip of the wing . toe ee 
First posterior cell equally broad over its whole length 
Front deeply excavated ; eyes very prominent ; 
third basal cell drawn out 
Front not excavated ; eyes as usual; 
- into a long point . 
. Third basal cell obtuse, truncated or rounded at its termination 
Rhopalomera, Wied. 
5. 
Rhinotora, Schin. 
Stictomyia, Big. 
6 7. 
Third basal cell inferiorly pointed, often drawn out into a lobe . 15. 
7, Third antennal joint slender, much longer than the second . 8. 
Third antennal joint elliptical, oval cr rounded, not much longer 
than the second 9, 
. Front somewhat prominent ; 
discal cell on the upperside limited 
by a rectilinear vein . Ce ee 
Front not prominent; the vein limiting the discal cell on the 
upperside slightly inflexed before the small cross-vein . 
Auxiliary vein coalescent with the first vein, the mediastinal cell 
Stenopterina, Macq. 
Rivellia, Rob.-Desv. 
9. 
therefore inconspicuous . . . Mischogaster, Macq. 
Auxiliary vein distinctly separated from the first vein 10. 
10. Femora inferiorly spinose . 11. 
14. 
Femora without spines. . . - 
BIOL. CENTR.-AMER., Dipt., Vol. IL, October 1898. 
3¢ 
