364 SUPPLEMENT. 



some little spine-like hairs near the apex ; second and third joints short, black, bent on each other ; 

 fourth joint black, of moderate length, with a row of small spines below ; fifth joint small, black. 

 Middle and hind tibiae with few and small bristles. Wings with the usual two blackish cross-bands, the 

 basal half yellow before the third vein, the apex considerably hyaline ; fork of the fourth vein with an 

 acute but rounded angle at its bend. 

 Length 7 millim. 



Bab. Mexico, Tierra Colorada in Guerrero (H. H. Smith). 

 One male. 



29. Psilopus tonsils, sp. n. 



J . Face pure green, depressed across the middle, with white pollen ; antennae black, the second joint with 

 one or two rather long bristles only on the underside ; front bright green, with some pale hair on the 

 sides. Thorax bright green, the sides not very heavily pollinose ; halteres pure yellow. Abdomen with 

 black bands, which are wider towards the tip ; hypopygium closely drawn up (and hence difficult to 

 describe), but apparently of moderate size, with some protruding, jagged, black organs. Middle and hind 

 coxae, and the hind trochanters, black ; hind femora infuscated at the tip, especially above ; tarsi simple 

 in structure, without rows of bristles or other special characters. Wings subhyaline ; venation as in 

 P. caudatus. 



Length 4 millim. 



Hah. Mexico, Frontera in Tabasco (H. H. Smith). 



One male. 



GNAMPTOPSILOPUS. 



Gnamptopsilopus, Aldrieh, Kans. Univ. Quart, ii. p. 48 (1893). 



Table of the known Species, based on males only. 



1. Antennae entirely black 2. 



* At least the basal joints yellow 6. 



2. Femora yellow 3. 



Femora black 5. 



3. Fore coxae with black bristles at the tip (Mex.) infumatus, sp. n. 



Fore coxae with pale bristles at the tip 4. 



4. Base of the hind coxae and hind margin of the thorax pale (U.S.) . . [costalis, Aldr.] 

 The same parts dark (U.S.) [scintillans, Loew.] 



5. Wings without black markings (Mex.) ciliipennis, sp. n. 



Wings black, except the apex and hind margin (Mex.) ...... dimidiatus, Loew. 



6. Dorsum of thorax yellow, with a green or blue stripe 7. 



Dorsum of thorax wholly metallic 8. 



7. Pleurae yellow; middle tibiae and metatarsi with erect cilia (W.I.) . [flavidus, Aldr.] 

 Pleurae with an indistinct dark spot ; tarsi plain (W.I.) [dorsalis, Loew.] 



8. Thoracic dorsum opaque, dusted; abdomen not pale at the base (U.S.). [pallens, Loew.] 

 Thoracic dorsum shining ; abdomen usually pale at the base .... 9. 



9. Middle coxae infuscated on the outer side at least to the middle ... 10. 

 Middle coxae wholly oi almost wholly yellow 13. 



10. Costa ciliated, with an irregular projection forward near the tip (U.S.). [psittacinus, Loew.] 

 Costa without such projection 11. 



11. Middle femora shortened, dark at the base, the tibiae elongate (U.S.) . [filipes, Loew.] 

 Middle femora normal, pale .12. 



