220 WILLIAM J. FOX. 



Occ^iput and clieeks not strongly margined ; pronotnm not very large nov 

 strongly margined, the lateral tooth short ; central longitudinal furrovv 



of middle segment broad 9. 



P.^Scape entirely black ; occiput scarcely margined posteriorly ; markings 



whitish yellow atriceps. 



Scape yellow in part; occiput distinctly margined posterio7-ly ; markings 



bright yellow bruuneipes. 



10. — Pronotum with the transverse furrow very broad and shallow, particularly 

 toward the sides ; greater jiart of tibiie yellow, the pronotum and meta- 



notnm always spotted 11. 



Pronotum with the transverse furrow not very broad, but deep ; greater jiart 



(tf tibife black parvuliis. 



11. — Abdomen broad, not longer than head and thorax united ; posterior face of 

 middle segment distinctly enclosed; scape entirely yellow. 



eorrugatuN. 



Abdomen elongate, longer than head and thorax united ; posterior face of 



middle segment not distinctly enclosed in consequence of the ridge, 



dividing it from the upper surface being more or less obsolete; siape 



only in part yellow deiiticiilatus. 



12. — Joints 1 and 2 of tlagelhim with a huge tooth or production beneath, the 

 third and fourth joints much less distinctly toothed, the combined length 

 of the first two joints as great as that of joints 3-6; fore femora black 



and yellow 13. 



Joints 1-4 of flagellum equally dentate beneath, the combined length of the 

 first two joints not greater than that of joints 3 and 4 ; fore femora 



rufous, striped with black and yellow nigrif'i'Oii$$. 



13. — Sides of middle segment coarsely striated, up])er surface and posterior face 



coarsely rugose. Species Eastern <»b*«eurus. 



Sides of middle segment rather finely striated, upper surface and posterior 



face only tolerably rugose. Species Western §^racili!>iKiiiius. 



14.— Dorsulnni not striated, either finely or rugosely punctured 15. 



Dors\ilum striated, transversely on anterior portion, posteriorly longitudi- 

 nally so (fore femora beneath armed with a sharp spine) 29. 



1.5. — Abdomen above not distinctly punctured, or impunctate 1(5. 



Abdomen above distinctly punctured, particularly the first segment 17. 



16. — First and seccmd joints of medial tarsi very strongly produced at apex 

 within, almost spinose ; first joint of the flagellum distinctly longer than 



the second ; fore femora reddish anteriorly i^exinaciilatus. 



First and second joints of medial tarsi scarcely produced at apex within ; 

 first joint of flagellum but little longer tliRU the second ; foi'e femora iu 



front yellowish trifasciaf HS. 



17. — Fore tarsi not or but slightly flattened ; the first joint of medial tarsi not 



angular IS. 



Fore tarsi distinctly flattened; the first .joint of medial tarsi short, nioi-e or 



less angular 26 



18. — Antennae more or less emarginatt^ beneath 19. 



AntennsE entire, subclavate, not eraarginate 28. 



19. — Head with large, separated punctures, except iu one case ; middle segment 



laterally, at least the posterior face, with a series of strong fovese. • • -20. 



Head closely and rather finely punctured ; middle segment without lateral 



foveae 24. 



