Fosso7-ial ITi/menoptera of North America. 395 



The legs are much slenderer and smoother, the fore femora long and 

 slender, fore tarsi slenderer and more slightly spined, hind tarsi 

 minutely hirsute. 1st joint much shorter than in Cemonus. The 

 shorter head, large mandibles, especially in $ , resembling those of 

 Eumenes, the prominent revolute visor-like labrum and smooth front, 

 the horizontally and great extent of the meso-thoracic flanks, compared 

 with the inclined flanks of the meta-thorax, the differences of the wing, 

 as stated above, and the slender, smoother legs, and especially the sub- 

 sessile abdomen, with its nearly cylindrical and obtuse tip, separate 

 this from Cemonus and Pemjphredon. 



Passalaecus mandibularis. 



Pcmphrcdon mandibularis, Cress., Proc. iv. p. 4S7. (1865). 

 Our eastern specimens from Maine and Massachusetts, (Norton), do 

 not differ from specimens from Colorado Territory, (Coll. Ent. Soc. ) 

 It seems to be a common and widely distributed species. 



Passalaecus annulatus. 



Cemonus annulatus, Harr. Cat. Ins. Mass., p. 69. (1835). 



Pcmphrcdon annularis, Say, Bost. Jour. jSTat. Hist., i, p. 379. (1836). 



Pcmphrcdon annulatus, Smith, Cat. Hym. B. M. iv. p. 429. (1S56). 



% . Front converges more sensibly, and is slightly contracted oppo- 

 site the insertion of the antennae; clypeus and orbits slightly hirsute ; 

 clypeus subacute; mandibles small, white, much smaller and shorter 

 than in 9 . Antennas with the scape stouter and shorter than in 9 . 

 white on the basal half, the remainder fuscous ; joints of the flagellum 

 fuscous annulated with testaceous white. Otherwise like the 9 . 

 Length, .19 inch. 



9 . Head narrow, more narrow than in P. mandibularis, more 

 acute, more distinctly carinated and dark; clypeal region smooth, just 

 above obsoletely sericeous, more naked than in P. mandibularis ; man- 

 dibles white, of the usual form, fuscous on edges and tip; palpi pale tes- 

 taceous; antennae more clavate than in P. mandibularis, scape whitish, 

 basal joint fuscous, remainder brown-black, thorax smooth, very 

 minutely punctured; lower edge of meso-scutum with a marginal row 

 of distinct short rugae, directed inwards. Prothorax slightly sericeous. 

 Propodeum conflueutly punctured with fossulets, with a slightly marked 

 mesial furrow ; on the flanks are longitudinal prominent ridges, with 

 smaller intermediate transverse striae; more posteriorly, with minute 

 fossulets between the unequal irregular transverse striae. Nervures of 

 the wing ferruginous; pterostigma blackish. Fore and middle legs, 

 entirely fuscous, including the trochanters, hind trochanters fuscous, 

 femora black, fuscous at tip, which is concolorous with the rest of the 



