WILLIAM J. FOX. 6 



16". Dorsulum striato-iHuictate ; abdomen entirely black ; all tarsi yellowish. 



ctialcifrons. 

 Dorsulum not striate ; abdomen more or less red ; tarsi not yellowish 17. 



17. Clypeus transverse, about three times wider than long in the middle ; petiole 



broad, flat above, widened apically, where it is depressed. 



argentifrons. 



Clypeus somewhat hexagonal, not three times wider than long in the middle ; 



petiole rather slender, convex above, scarcely widened apically 18. 



18. Sculpture of middle segment unusually fine and even, the posterior surface 



finely striated ; petiole slender, not sulcate above CressiiOiiii. 



Sculpture of middle segment coarse, but not unusually so, the posterior sur- 

 face rugoso-reticulate : petiole stouter, bisulcate above borealis. 



19. Petiole at most bisulcate, rather slender; clypeus at most bidentate 20. 



Petiole deeply trisulcate above, rather broad ; clypeus 4-dentate, the medial 



teeth largest clypeatiis. 



20. Clypeus three times broader than long; sculpture of posterior surface of 



middle segment rather coarse pauper. 



Clypeus not more than twice broader than long; sculpture of posterior sur- 

 face of middle segment more subtile iiniciiictiis. 



21. Sculpture of middle segment fine ; petiole about half as long as hind femora, 



convex above, scarcely widened apically proxiniiis. 



Sculpture of middle segment co^irse ; petiole about two-thirds as long as hind 

 femora, flat above, widened and depressed apically basiriifiis. 



22. Abdomen black, with bluish reflection, apical margin of segments testaceous: 



mesopleurffi rugoso-punctate tibialis. 



Abdomen more or less red ; mesopleurse with large, sparse punctures. 



suflTiisus. 



MALES. 



1. Petiole distinctly trisulcate above 2. 



Petiole not trisulcate above 8 



2. Entirely black 3. 



Apex of first and base of second abdominal segment red ciypeatiis. 



3. Antennae unusually long, longer than head and thorax 4. 



Antennae stouter, not or but little longer than head and thorax 5. 



4. Flagellum scarcely dentate beneath, not pale ; tarsi whitish : petiole deeply 



sulcate Ioiigicoriii!«. 



Flagellum with joints 4-6 distinctly dentate or nodose beneath ; tibifp,. except 

 medially, and tarsi yellowish ; sulci of petiole shallov*' inellipes. 



5. Enclosure of middle segment with a central smooth area (i 



Enclosure of middle segment with a smooth area, hut with transverse stria- 



tions medially 7. 



6. Petiole very robust ; tarsi dark testaceous; posterior surface of middle seg- 



ment scarcely depressed iiiger. 



Petiole rather slender, much slenderer than in nujer : tarsi whitish ; posterior 

 surface of middle segment depressed or concave leucopiis. 



7. Antenna? shorter than head and thorax ; sculpture of juiddle segment finei' 



than in the allied species, the enclosure large, greatly drawn-out apically. 

 so that it includes almost two-thirds of the length of the segment ; head 

 with separated punctures <'yliii«lricus. 



TRANS. AM. ENT. SOC. XXV. JANUARY. 1898. 



