2 S. W. WILLISTON. M. D. 



In using the table, the terminal spur of the front tibiae should be 

 sought for with care ; in some of the species it is very small. It lies 

 across the inside of the joint between the tibia and metatarsus, and is 

 more or less oblique and bent. 



Table of genera of the N. A. Dasypogoninae and Laphrinae 

 (north of Mexico). 



A. 

 Dasypogoninae. — Marginal cell of the wing open 



]. — Front tibiae with a terminal claw like spur 27. 



Front tibiae without such spur 2. 



2. — Palvilli rudimentary or wanting 3. 



Pulvilli normal 4. 



3. —Face very narrow ; abdomen very long, slender, narrow on proximal part ; hind 

 ^ legs elongate, slender L.eptogaster. 



Face moderately narrow: abdomen not unusually long, broader at base; hind 

 legs not elongate Ablaiitatus. 



4. -Head narrow, about as high as broad ; face narrow above, broader and 



swollen below, in large part covered with hair. Large elongate species. ..5. 



Head very obviously broader than high 7. 



5. — Antennae with a terminal style fi- 



Third joint of antennae very long, without style; fourth posterior cell closed 

 before the border of the wing. Black species with or without red on the 



abdomen Osprioccriis. 



6.— First posterior cell open, not closed before tlie border of the wing. 



Stenopog^on. 

 First and fourth posterior cells closed before the border of the wing; third 



joint of antennae shorter, style longer Scleropogon. 



7. — Fourth posterior cell closed before the border 8. 



Fourth posterior ^11 wide open, rarely nearly closed 12. 



8.— Antennae elongate, of five joints (Myela-phus) 1.3. 



Antennae not elongate, of three joints, and a terminal style 9. 



9. — Face bare, except on oral margin; abdomen elongate, cylindroidal ; anterior 

 intercalary vein continuous, or nearly so, with the fourth vein, the last 

 section of fourth vein oblique, sinuous, closing or inuch narrowing the 



broad first posterior cell. Large, or very large species Iflicrostyliini. 



Face pilose or hairy, more convex 10. 



10. — Abdomen cylindrical, not narrow at the tip, elongate; near the base of 

 second and third segments with white pollinose emarginate cross-bands ; 



wings blackish .Diasonias. 



Abdomen less elongate, with five or six white pollinose cross-bands 11, 



11. — First posterior cell open, scarcely narrowed, face broad Lapliystia. 



First posterior cell much narrowed, or closed Triclis. 



12, — Antennae elongate, composed of five joints; nearly bare species 13. 



Antennae less elongate or short, of three joints, with or without a short or 



slender style 14. 



13. — First and second joints of antennae of nearly equal length, third elongate, 

 fourth short, fifth elongate and densely pubescent, third and fourth not 

 lobed at tip Ceratiirgus. 



