APPENDIX. 3^5 



able attenuation before, and the abdominal petiole is not 

 visible. 



ACAENITUS, Latr. 



(tdnomalon, Jur.) 



A. stigmapterus. $ Black ; incisures of the feet white. 



Inhabits North-west Territory. 



Thorax densely punctured ; two dilated grooves conflu- 

 ent behind ; scutel united to the thorax by a carinated line 

 each side ; wings tinged with fuliginous ; nervures black- 

 ish; stigma terminated before by a small white spot; me- 

 tathorax with large confluent punctures ; terminated on 

 each side behind by a short conic process ; pleura and 

 pectus polished ; tibiae at base, first joint of the tarsi at base, 

 and near the tip of the tarsi, white. 



Length more than one inch. 



Well distinguished by the white points on the wings, 

 and the white annulations of the feet. The head in my 

 specimen is deficient. 



IBALIA, Latr. 



I. anceps. Dull ferruginous; wings blackish ; abdomen, 

 piceous. 



Inhabits Arkansa and St. Peter's rivers. 



Head with a black curved line at base of the antennae; 

 collar abruptly elevated at the anterior edge, and slightly 

 emarginate in the middle ; near the neck black ; thorax 

 transversely wrinkled, and with three longitudinal im- 

 pressed distant lines, of which the intermediate one is 

 black, and the lateral ones black on the exterior side ; scu- 

 tel scabrous, abruptly elevated at tip, and emarginated ; 



Vol. II. 43 



