52 



2. Abdomen black, the last segment usually grayish 3. 



Abdomen black, marked with gray 6. 



3. Posterior cross- vein less than its length from the hind margin 4. 



Posterior cross-vein more than its length from the hind margin 5. 



4. Costal and first basal cells subequal anthrax Loew. 



Costal cell much longer than the first basal cell velutina Loew. 



5. Third section of the fourth vein much longer than the fourth, antennae 



usually yellowish flavicornis Loew. 



Third and fourth sections of the fourth vein subequal, antennae usually 

 dark brown minorata Banks. 



6. Abdominal bands continuous 7. 



Abdominal bands interrupted, costal and first basal cells equal, halteres 



black banksi, sp. n. 



7. Costal and first basal cells subequal, haltergs yellow taeniata Snow. 



Costal cell longer than the first basal cell, halteres black . infumata Haliday. 



Females. 



1. Posterior cross- vein less than its length from the hind margin, costal cell 



much longer than the first basal cell 2. 



Posterior cross-vein less than its length from the hind margin, costal and 



first basal cell subequal 3. 



Posterior cross-vein more than its length from the hind margin, costal and 



first basal cell subequal 4. 



Posterior cross-vein about its length from the hind margin, costal cell much 



longer than the first basal cell, abdomen with broad continuous gray 



bands, antennae and legs yellow pallipes Loew. 



2. Abdomen opaque black, legs and halteres black velutina Loew. 



Abdomen with gray spots on the sides of the segments obscura Loew. 



Abdomen with the gray bands wanting on the second segment and on the 



third broadly interrupted, thorax with a tridentate black mark, halteres 

 black infumata Haliday . 



3. Abdominal bands not interrupted, legs black anthrax Loew. 



Abdominal bands not interrupted, legs brown taeniata Snow. 



Abdominal bands on the second, third and fourth segments broadly inter- 

 rupted banksi, sp. n. 



4. Third section of the fourth vein much longer than the fourth, antennae 



yellowish flavicornis Loew. 



Third and fourth sections of the fourth vein subequal, antennae brownish 

 minorata Banks. 



Platypeza taeniata Snow. 



P. taeniata Banks, Journ. N. Y. Ent. Soc, vol. 23, p. 214, pi. 17, f. 8 (female 

 only), 1915. 



This species is based on a female collected in Illinois. Snow 

 says that it must be near P. boletina Fallen of Europe, whose black 

 abdominal bands are widened in their middle. In the male the 

 bands are not widened or but very slightly in a few specimens. 

 In the female, however, this character is extremely variable and 

 in a number of specimens the bands are considerably wider in the 

 middle as figured by Banks. It resembles the female of P. 

 anthrax Loew but is distinguished by its yellowish legs and margin 

 of the humeri. I am inclined to think that it may prove to be the 

 same as P. boletina Fallen. 



The male figured by Banks represents a new species which I am 

 calling P. banksi. 



