APPENDIX.
339
ated; wings hyaline, nervures fuscous; pleura with a small dot before the wing; feet black; tibiae sericeous, white on the exterior base; tarsi white; tergum, second segment at tip each side with a small white spot.
Length three-tenths of an inch.
This species corresponds in its generic characters precisely with Arpactus, Jurine, and of course possesses those oblique parallel lines of the metathorax which Jurine mentions as distinguishing this genus.
PEMPHREDON, Latr. Fabr.
1.  P. concolor. Black, minutely punctured; metathorax with dilated punctures; abdomen glabrous.
Inhabits North-west Territory.
Head with minute pubescence, more distinct on the front; mandibles obtusely bifid at tip, immediately above which are two obtuse teeth; punctures minute, sparse on the vertex ; thorax with a slightly impressed, longitudinal line, from which proceed numerous, minute wrinkles, curving outwards and backwards; punctures larger than those of the head; wings slightly fuliginous, nervures blackish; metathorax with dilated punctures, or slightly impressed cavities ;feet somewhat sericeous; abdomen polished, im-punctured; petiole moderate.
Length of the body nearly seven-twentieths of an inch.
This is allied to P. unicolor, Fabr.
2.  P. inornatus. Black, immaculate, punctured; abdo- m men impunctured, polished; petiole nearly one-third the length of the abdomen.
Inhabits Pennsylvania.
Wings hyaline, very slightly tinged with dusky, the