352 BULLETIN UNITED STATES GEOLOGICAL SURVEY. [YolY. 



of segments one, two, and three fuscous ; broad "bands at tlie base of 

 segments one to four, narrowed in the middle, two spots at the base of 

 the fifth segment, base of the first ventral segment, and spots on the 

 second and third ventral segments yellow ; the second to the fifth ven- 

 tral segment stained with fuscous. 



P. interruptus (Say) agrees in the structure of the feet and the form of 

 the labrum and mandibles, but the mandibles have two short and blunt 

 teeth near the apex. As the wings of the Kansas specimen are badly 

 worn, it is probable that the teeth of the mandibles have been worn off 

 also. 



P. navus Cress, appears to be exactly intermediate in coloration be- 

 tween this species and P. interruptus. From nmnis this species differs 

 in the much paler ground-color and the more extended yellow markings 

 throughout, and in the absence of all black from the thorax, excepting 

 the pectus and incisures. In the Southern States occurs another form 

 resembling interruptus more in the markings, and ichneumoniformis in 

 the ground-color. It is probable that the four wiU be united under one 

 variable species. 



10. P0^O>ILUS WILLISTONin. sp., 9 . 



Length 21""". Dark ferruginous; wings fuscous, with a blue reflection, 

 a large subapical spot on the anterior wings and the broad posterior 

 borders of the posterior wings paler fuscous; costal and marginal 

 cells and all the nervures of the anterior wings, except the apical ones, 

 stained with yellow. Clypeus truncate at the apex. Labrum cleft in 

 the middle, the epipharynx large and broad, extending beyond the 

 labrum proper. Mandibles. long, with two teeth on the inner border 

 beyond the middle, the proximal tooth the smaller. The face yellow- 

 ferrugiuous, a broad line above the median section of the clypeal suture, 

 and a space enclosing the ocelli and connected with the insertion of the 

 antennse black, narrow posterior orbits yellow; mandibles yellowish, 

 the tips blacli, antennse blacli, the five basal joints ferruginous. Poste- 

 rior margin of i)rothorax subangular ; posterior border of prothorajs, the 

 tegulse and a line above, the x)ostscuteUum, angles of metathorax, tips 

 of femora, stripe on tibiae, and the tarsi dull yellow; tibiae and tips 

 of tarsal joints fulvous; prothorax anteriorly and the anterior border 

 of the mesothorax, sutures of the thorax, the pectus, the coxae, tro- 

 chanters and base of femora (extending into a stripe on the posterior pair) 

 black. Claws of the four i)osterior tarsi with a simple median tooth ; 

 claws of the anterior tarsi with a stout truncated tooth beyond the 



wliicli I regard as a part of the seventli dorsal segment. These are the only instances 

 in Tzhich an extei'nal seventh segment has been recognized in the 9 of the Aculeate 

 Hymenoxitera. In Priocnemis the sixth dorsal segment is iirodnced and as long as sixth 

 ventral, Tvhich it completely covers. Since the above left my hands I have fonnd this 

 seventh dorsal segment of the $ externally apparent in Pelopceus, Priononyx, Harpacto- 

 ims, and AinmopMla, and its edge apxDarent in Chalyiion, Chlorion, Isodoniia, and Spliex — 

 i. e., in all the typical Sphecidte — , being in each case closely ai)pressed to the sixth 

 ventral segment and forming the real dorsal valve. 



