OF PHILADELPHIA. 63 



2. A. SERICEUS. — Sericeous, somewhat golden ; thorax with a 

 dilated brown vitta ; colors of the tergum changeable. 



Inhabits Pennsylvania. 



Antennae dull yellowish ', thorax, vitta attaining the scutel, and 

 in a particular light changing to bright yellow ; wings ferru- 

 ginous, areolae of the thinner margin, and of the tip dusky ; feet 

 light chestnut, somewhat sericeous ; tergum dark-brown, with 

 bright yellow posterior margins to the segments when viewed 

 from behind or above, bright yellow or golden, with brown pos- 

 terior margins to the segments when viewed from before ; venter 

 blackish-brown, in a particular light ferruginous. 



Length rather more than one and one-tenth inches. 



This beautiful species is referable to Meigen's first tribe. [49] 



OMMATUS Wied. 



0. TIBIALIS. — Black-brown ; abdomen black ; tibia white. 



Inhabits Pennsylvania. 



Front and hypostoma golden-yellowish ; vibrissse gray, near the 

 antennas black ; occiput silvery, nearly glabrous ; thorax dark- 

 brown, approaching black, with an obsolete narrow brown line on 

 the middle ; scutel, metathorax, pleurae, pectus, and coxse silvery ; 

 wings pellucid, with black nervures ; thighs dark chestnut ; tibia 

 white, intermediate and posterior ones near the tip, and tarsi brown . 



Length eleven-twentieths of an inch. 



DIOCTRIA Meig. . 



1..D. 8-PUNCTATA. — Subglabrous, black; abdomen with four 

 white spots on each side. 



Inhabits the United States. 



Body black, nearly glabrous, polished ; front yellowish ; thorax 

 with three yellow lines, of which the exterior ones are dilated 

 before, and include a dusky spot ; feet testaceous, tibia and tarsal 

 joints tipped with blackish ; tergum punctured, and with a white 

 spot at the lateral tip of the second, third, fourth and fifth segments. 



Length three-tenths of an inch. 



This species is an inhabitant both of the western and eastern 

 States. The first joint of the antennae is [50] considerably longer 

 than the second, though not double its lengthy and the terminal 

 joint is elongated, subcylindrico-compressed, obtuse at tip, with a 

 1823.] 



