OP NATURAL HISTORY. 768 



second and third segments, each with a yellow band widely iutcr- 

 rupted in the middle, the anterior one largest : feet honey-yel- 

 low : thighs black at base. 



]jcrigth three-tenths of an inch. 



Readily distinguishable from X. 5-.<tj>i'iiosus nob. Resembles X. 

 intcrruptus F. but the areola) of the nietathoracic spines are not 

 gilded in that species. 



PSEN Latr. 



1. P. MELLIPKS. — 9 Black, with a silvery reflection ; antennae 

 at base, tibiae and tarsi piceous. 



Inhabits Indiana. 



Body black : head beneath the antennae yellowish-silvery : oc- 

 ciput with a silvery reflection : antennas to the seventh joint 

 honey-yellow: mandible piceous: thorax with longitudinallv 

 confluent punctures, a slender transverse line before, four or six 

 obsolete spots near the scutel and two large obvious ones near 

 the insertion of the petiole of the abdomen : wings hyaline ; ner- 

 vures black stigma brown ; second cubital cellule receiving both 

 recurent ncrvures : abdomen immaculate, with a few hairs to- 

 wards the tip ; petiole as long as the posterior tarsi or rather 

 longer, arcuated, piceous : tibiae and tarsi piceous or honey-yel- 

 low ; anterior })air with dense, short, golden hair. 



Length nearly eleven-twentieths of an inch. 



Very similar in form and color to P. afrafum Fabr., [370] 

 which, however, has the second and third cellules each receiving 

 a recurrent nervurc, and the petiole is propdrtionally rather 

 shorter. 



2. P. LEUCorus. — Black; hypostoraa silvery: tarsi white. 



Inhabits Indiana. 



9 Body black, with a slight silvery reflection : antenna; im- 

 maculate : hypostoma entirely silvery : thorax with minute, lon- 

 gitudinal lines on the disk : wings hyaline : ncrvures blackish ; 

 second cubital cellule receiving the two recurrent ncrvures: ter- 

 gum impunctured, polished ; petiole slightly arcuated, rather 

 shorter than the posterior tarsus : tarsi white, dusky towards the 

 tip. 

 1837.] 48 



