LEPTID7E. 43 



at its tip there are two triangular, sharp, flat, chitinous hooks, 

 and below them some stiff bristles. The booklets serve as 

 aids in boring in the sand and to fix themselves ; the organ on 

 the fifth segment enables the larva to seize and hold its prey, 

 and also in constructing the pitfalls. The larvae of the Lep- 

 tinse in general are cylindrical, with or without fleshy abdom- 

 inal legs. The last segment has a transverse cleft, the portion 

 above which is provided with two, often backward-bent points 

 or processes ; the under part is obtuse, with the two stigmata 

 between them. 



TABLE OF GENERA. 



1. Third joint of the antennae complex, the antennas more or less elongated ; 



five posterior cells present. . . . . . . . 2 



Antennae short or but little elongated, the third joint simple, with a ter- 



minal or dorsal arista or a terminal style; face small, excavated; 



proboscis short ; some or all of the tibia? spurred. . 



2. All the tibiaa with spurs. . . . ... XYLOPHAGIN^E. 



Front tibia? without spurs. ..... ARTHROCERATINA:. 



XYLOPHAGIN.E. 



1. All four posterior veins (i. e. the veins separating the posterior cells) 



arise from the discal cell ; head small ; scutellum with spines. 



COENOMYIA Latreille. 



The last posterior vein arises from the second basal cell, the fifth pos- 

 terior cell hence not contiguous at its base with the discal cell ; 

 scutellum without spines. ........ 2 



2. Third joint of the antennae acute at tip, . . ARTHROPEAS Loew. 

 Third joint of antenna? not acute at tip. . . . . . .3 



3. Fourth posterior cell closed ; the third joint of the antennae much elon- 



gate, composed of numerous, distinct divisions, often pectinate; eyes 



emarginate near the antennae. . . . RHACHICERUS Haliday 



Fourth posterior cell open ; third joint of antennae composed of eight 



annuli, indistinctly separated. . . . XYLOPHAGUS Meigen. 



ARTHROCERATIN^E. 



1. Fourth posterior cell open. . . ... . . . 2 



Fourth posterior cell closed. (Subula preoc.) SUBULA OMYIA noin. nov. 



