1897.] NATURAL SCIENCES OF PHILADELPHIA. 259 



second subraarginal subquadrate, third larger narrowed about one- 

 half to marginal. Length 19 mm. 



Chapada. 



This species is remarkable in the bituberculate middle-segment. 



Pompilus (Aporus) quadrimaculatus Sm. 



Chapada (March). One example. 



Pompilus (Aporus) minutus Sm. 



Santarem. Three specimens. 



The following table will aid in determining the new species of 

 Pompilus preceding : 



1. Females, 2. 



Males, 15. 



2. Middle segment rounded, unarmed, 3. 



Middle segment strongly bituberculate : entirely reddish ; wings 



yellowish, rutilans. 



3. Claws armed with a tooth within, 4. 



Claws bifid, 11. 



4. Basal vein and cubital vein of hind wings interstitial, ... 5. 

 Basal vein and cubital vein of hind wings not interstitial, . 10. 



5. Steel-blue; length 10? mm., mundulus. 



Otherwise colored, 6. 



6. Body entirely black, 7. 



Body more or less red, 8. 



7. Thorax not silvery; abdomen obscurely blue, the fifth segment 



with pale, sericeous pile, echinatus. 



Thorax maculated with bright silvery pubescence ; abdomen 

 grayish, argenteomaculatus. 



8. Thorax black, subopaque, 9. 



Thorax maculated with bright silvery pubescence, . triquetrus. 



9. Front distinctly striato-punctate, partitus. 



Front smooth, or very finely punctured, deceptus. 



10. Head and abdomen fuscous; thorax brownish; wings with 



costal half fuscous, vinicolor. 



Head and thorax black ; abdomen brownish ; wings yellowish, 

 exquisitus. 



11. Third submargiual cell very large, fully twice the size of second, 



not petiolate, 13. 



Third submarginal small, not twice the size of second, . . . 12. 



