380 Dr. A. S. Packard, Jr's Revision of the 



and thorax together, and the wing characters given above, will easily 

 serve to separate the females of this genus from Blepharipus. 



Another good. generic character is the great lateral extension down- 

 wards of the ineso-scutum, so that the tubercle is placed unusually far 

 down below the insertion of the wings ; and also the very square scu- 

 telluin, which is as long as broad. 



The % differs from Blepharipus by its shorter, more transverse, ellip- 

 tical head, pedicellate abdomen, and in the unusual distance between 

 the eyes, reminding us of Trypoxylon and Mimesa, whose form this 

 genus imitates. Also in the large size of the hardly carinated clypeus, 

 with its rounded revolute front edge, are good characters. In these 

 respects the European B. clavipes agrees with ours. But the present 

 species evidently will have to fall into a lower section of the genus, 

 apart from the European species, which departs less from the type of 

 this group centering about Orabro. 



Thus in B. clavipes the clavate antennae have throughout, simple 

 cylindrical joints, neither pinced in or expanded. The head is also 

 more like the type of Orabro, being more cubical, though differing 

 much still from Blepharipus, which connects it with Crabro. B. clavi- 

 pes has also the hind legs even longer and slenderer than in the two 

 anterior pairs, especially the tarsal joints. 



The great specific differences existing in this genus, show the neces- 

 sity of large material from both continents in studying the proper ge- 

 neric characters, which we can scarcely as yet hope to render at all 

 perfect. 



Rhopalum pedicellatum, n. sp. 



% . Head black, deeply impressed in front of the ocelli ; orbits sil- 

 very half way from the insertion of the antennae to the ocelli; clypeal 

 region silvery, clypeus unusually large and broad, front edge revolute. 

 Palpi pale testaceous, antenna? with scape yellow, flagellum with the 

 basal joints brown above, testaceous beneath, terminal joints alternately 

 dark and livid white, two terminal joints dark, tip of last one testaceous. 

 Mandibles pale yellow, piceous at extreme tip, black at base. Surface of 

 the body smooth and highly polished, with very minute shallow punc- 

 tures; tubercle very small, thin, scale-like, pale yellow; rest of the 

 thorax entirely bl ack ; wing-pieces yellow, tegulae testaceous, this color ex- 

 tending on to the base of the costa of wing; nervures brown; wings clear, 

 iridescent. Thoraco-abdomiual ring (propodeum) entirely smooth, not 

 rugose on the sides, with a sparse silvery pubescence on the flanks, not 

 reaching to the obscure semi-ovate or sublunate enclosure. 



