tibiae and tarsi, a rufous spot being near the knee ; 

 anterior thighs blackish on the inner side, with 

 a yellow exterior inferior margin, and numerous 

 spines on the inferior edge, of which one is very 

 prominent : tergum, at the base of the first and 

 second segments, black, the former margined 

 with yellow: venter black at base, segments 

 broadly margined with yellow. 



Female. The yellow colour, and marginings, 

 excepting on the feet, and on the first segment of 

 the thorax, obsolete ; the wings are darker than 

 those of the male, and the hyaline portion of the 

 wings is tinctured with a shade of the general 

 colour. 



OBSERVATIONS. 



A specimen of the female of this curious in- 

 sect, was presented to me, some time since, by 

 Mr. William Mason, of this city ; it was found 

 near Philadelphia, by Mr. Tyler. I had the 

 good fortune to find a male, when travelling with 

 Major Long's party on St. Peters' river, in the 

 North- West Territory. 



The middle figure represents the male, and 

 the lower figure the female. On the right is an 



PLATE XXV. 



