308 PROCEEDINGS OF THE NATIONAL, MUSEUM vol. 88 



Aside from the short antennal scape, this group is recognized by the 

 stout flagellum and the head being, when viewed from the dorsal 

 aspect, nearly one-half as long as wide. The vertex is broadly rounded 

 so that the anterior ocellus is directed somewhat dorsad rather than 

 in the usual anterior direction ; the thorax is, in all but one species in 

 this area, quite compact and broad (fig. 10, c). The teeth of the 

 metafemora are invariably minute and closely set, and the basal tooth 

 is usually no larger than the following ones. 



KEY TO SPECIES OF THE XANTHOSTIGMA GROUP 



1. Female, ninth abdominal sternite concealed, antennal scape 



slender ; 2 



Male, ninth abdominal sternite exposed, antennal scape broad 10 



2. Abdomen greatly elongated, acuminate, dorsal length of epi- 



pygium twice as great as length of eighth tergite tanais (p. 309) 



Abdomen short, dorsal length of epipygium equal to or slightly 



less than length of eighth tergite 3 



3. Left mandible with three teeth juxta (p. 311) 



Left mandible with two teeth 4 



4. Interantennal projection with a thin, conspicuously projecting 



anterior lamina (as in fig. 7, g) arcana (p. 313) 



Interantennal projection either smooth or with a minute anterior 



carina 5 



5. Dorsum of pronotum with a distinct anterior carina (fig. 10, c) 6 



Dorsum of pronotum acarinate at anterior margin 7 



6. Petiole less than twice as long as wide apaiis (p. 315) 



Petiole three times as long as wide melana (p. 316) 



7. Outer dorsal surface of metacoxa glabrous 8 



Outer dorsal surface of metacoxa shagreened 9 



8. Lateral ocelli almost contiguous with compound eyes pallens (p. 319) 



Lateral ocelli separated from margins of compound eyes by a 



space at least equal to diameter of ocellus xantha (p. 320) 



9. Width of space between posterior ocellus and margin of com- 



pound eye less than diameter of posterior ocellus odontotae (p. 321) 



Width of space between posterior ocellus and margin of com- 

 pound eye greater than diameter of posterior ocellus- subobsoleta (p. 323) 



10. Thorax elongate, slender (fig. 10, b), width of posterior margin 



of mesopraescutum two-fifths its length tanais (p. 309) 



Thorax short, compact (fig. 10, c), width of posterior margin of 

 mesopraescutum one-half its length 11 



11. Left mandible with three teeth juxta (p. 311) 



Left mandible with two teeth 12 



12. Interantennal projection with a thin, conspicuously projecting 



anterior lamina (as in fig. 7, g) arcana (p. 313) 



Interantennal projection either smooth or with a minute carina 13 



13. Outer dorsal surface of metacoxa glabrous 14 



Outer dorsal surface of metacoxa shagreened 15 



14. Lateral ocelli almost contiguous with compound eyes pallens (p. 319) 



Lateral ocelli separated from margins of compound eyes by a 



space at least equal to diameter of ocellus lecta (p. 317) 



