208 long's second expedition. 



the type of this genus. The first radial cellule receives the first 

 recurrent nervure and is nearly square, slightly oblong, and 

 nearly two-thirds the size of the second cellule, which receives 

 no recurrent nervure and is somewhat smaller than the third 

 cellule. The latter receives two recurrent nervures. The cu- 

 bital cellules are subequal, bounded beneath by an almost recti- 

 linear line, the third nearly attains the tip of the wing, leaving 

 the fourth cellule very small. The maxillary palpi also are 

 much shorter than those of the Swedish species. This disposi- 

 tion of the nervures will authorize the formation of a distinct 

 section in the genus. 



XIPHYDRIA Latr. 



1. X. abdominalis. — Black ; abdomen rufous. 

 Inhabits Pennsylvania. 



Head confluently punctured ; antennae short ; vertex with two 

 distant, longitudinal, yellow spots, and another [312] transverse 

 one on each cheek above ; thorax confluently punctured, margined, 

 and with three longitudinal impressed lines distant before ; wings 

 fuliginous; abdomen bright rufous; first segment above blackish; 

 feet piceous black. 



Length more than half an inch. 



The abdominal color of this species distinguishes it at once 

 from any other. In dromedarius the middle segments of the 

 tergum are rufous, but the terminal and three basal segments are 

 black, and there is a series of whitish lateral spots. 



2. X. tibialis. — Black; four lateral spots of the abdomen, 

 first tarsal joint and base of the tibia white. 



Inhabits Pennsylvania. 



Stethidium rough with confluent punctures, immaculate ; 

 wings hyaline, nervures dark fuscous ; feet black ; tibia white, 

 fuscous at tip; tarsi, first joint white; abdomen black, three mid- 

 dle segments and the penultimate segment, each with a white 

 spot on each side. 



Length more than two-fifths of an inch. 



This species resembles the camelus Fabr., and Urocerus annu- 

 latus Jur., but is less than half the size of either, and the former, 

 according to authors, has ferruginous feet and a smooth thorax; 

 the latter has a lateral white spot on each of the abdominal seg- 

 ments excepting the penultimate one. 



