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APPENDIX.
transverse one on each cheek above; thorax confidently 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 colour 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 middle segments and 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 Ueo-certjs annulatus, 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 segments excepting the penultimate one.
TARPA, Fabr. Le Peletier.
T. scripta. Black, with white lines and spots; abdomen rufous.
Inhabits North-west Territory and Arkansa.
Hypostoma on its anterior margin, mandibles and palpi, whitish; line upon the orbits extending from near the an-