178 U. S. NATIONAL MUSEUM BULLETIN 216 



Apical third of mandible not turned, in same plane as its condyles; yellow or 

 whitish on upper edge of pronotum not or rarely extending forward to 

 notaulus 51 



51. Mandible about 0.60 as long as width of mouth opening, its upper tooth 



unusually small; second lateral area of propodeum with hairs laterally and 



apicolaterally 43. fastigatus, new species 



Mandible about 0.77 as long as width of mouth opening, its upper tooth 

 moderately large; second lateral area of propodeum with hairs only in its 

 apicolateral corner 44. canidens, new species 



52. Face in profile much more strongly convex in its lower half than in its upper 



half, so that it bulges ventrally; head about 0.65 as long as high. 



52. ventricosus, new species 



Face in profile equally or less convex in its lower half than in its upper half; 



head about 0.75 as long as high 53 



53. Apical half of mandible not turned, its outer face in same plane as its condyles; 



second to fourth tergites often stramineous in apicolateral corners. 



49. pleuralis Cresson 



Apical half of mandible turned about 60° (in female, male unknown) from 



plane of its condyles; second to fourth tergites black or margined laterally 



with stramineous 51 



54. Combined face and clypeus about 0.89 as high as wide; apical margin of 



clypeus faintly concave in its medial 0.5; hind femur fulvous, white above 



at apex (fig. 196,d) 50. mesodon, new species 



Combined face and clypeus about 0.77 as high as wide; apical margin of 

 clypeus broadly concave; mandible exceptionally long; hind femur fulvous, 

 faintly infuscate above at apex (fig. 196,e) . . 51. megadon, new species 



I. STENOSTOMA GROUP 



Front wing 3.4 to 4.5 mm. long; head rather broad but tapered to a 

 narrow mouth; face rather flat, its interantennal process moderately 

 long but not approaching frons, the point making an angle of about 

 80 degrees; frons weakly convex, somewhat impressed near antennal 

 sockets; occipital carina dorsally and laterally complete but weak, 

 absent near hypostomal carina; clypeal margin weakly convex, its 

 median half sub truncate; head black, upper edge of face, narrow lower 

 lateral part of frons (sometimes complete to top of eye), and some- 

 times a spot at top of eye, ivory or pale yellow; notaulus present 

 anteriorly as a shallow pit; metapleurum with a few discal hairs, all 

 or mostly in its posterior half; costula incomplete or complete; median 

 longitudinal carinae and apical transverse carina of propodeum com- 

 plete; second lateral area of propodeum with hairs over its entire 

 surface, or its mesal part bare; nervulus beyond basal vein by about 

 0.6 its length; front spur of middle tibia about 0.70 to 0.88 as long as 

 hind spur; second segment of middle tarsus about 1.7 as long as wide; 

 hind tibia whitish on its basal 0.2 ±, the rest fulvous or darker; first 

 tergite about 1.4 as long as its width at the laterobasal corners; 

 second abdominal tergite about 0.7 as long as wide, with rather sharp 

 punctures, the interspaces of which are about 0.5 to 3.0 the diameter; 



