152 ERNEST A. BACK. 



10. Anterior intercalary vein continuous or nearly so with the fourth 



vein, the last section of the latter oblique, closing or much 

 narrowing the broad first posterior cell (PI. VI, fig. 4). 



Microstyluni. 



Last section of the fourth vein continuous with the preceding 



section, the first posterior cell not closed or narrowed 



(Central and South America) Archilestris. 



11. Abdomen cylindrical, elongate, male genetalia never meeting to 



close the anal opening; third antennal segment elongate.. 12. 



Abdomen less elongate, more flattened with five or six white 



pruinose (interrupted or entire) cross bands 13. 



12. Fore and middle femora on the underside with a patch of short, 



very stout bristles; third antennal segment without an 



excision on the inner distal half (Cuban) Sphageus. 



Femora without such patches of bristles; third antennal segment 

 with an excision on the inner half; near the proximal mar- 

 gin of the second and third abdominal segments with a 

 white or yellowish pruinose emarginate cross band (PI. 

 VII, fig. 2; PI. VIII, fig. 3) Dizouias. 



13. Scutellum with two or four stout bristles; veins at the outer ends 



of the discal and fourth posterior cells parallel or nearly 



so (PI. IX, fig. 4) Psilocurus. 



Scutellum without stout bristles; sometimes densely pilose or with 

 weaker hair-like bristles forming a fringe on the posterior 

 margin, or with both 14. 



14. First posterior cell wide open, scarcely narrowed; face broad (PI. 



V, fig. 6), vertex deeply excavated; style of antennae thick, 



distinctly two-jointed (PI. IV, fig. 1) Lapliystia. 



First posterior cell closed or nearly so; face narrower, more pro- 

 tuberant below; scutellum with a fringe of weak bristles 

 (PI. IX, fig. 3) Tricilis. 



15. Antennae elongate, composed of 5 segments; nearly bare species... 16. 

 Antennae less elongate or short, composed of three segments with 



or without a short or slender style 18. 



16. First segment of antennas about three times the length of the 



second, third elongate, the fourth and fifth of nearly equal 

 length; third and fourth segments at tip with two lobes 

 or processes, reaching to about the middle of the following 



segment (PI. X, fig. 3) Myelaphus. 



First and second segments of nearly equal length, the third 

 elongate, fourth short, the third and fourth segment not 

 lobed at tip (PI. IV, figs. 2 and 3) 17. 



17. Terminal segment of antennae short, rounded, naked, on the outer 



side with a projection bearing a short, forward directed 

 bristle (PI. VII, fig. 6) Ceratiirg-opsis. 



