• NORTH AMERICAN HYMENOPTERA. 143 



finely striato-punctate tliroughout ; middle segment above coarsely and irregu- 

 larly rugulose, posterior with coarse transverse striations, tolerably well enclosed, 

 the surrounding ridge, however, not as well developed as in corrugatus % ; first 

 joint of medial tarsi not much longer than the following three united, the second 

 joint as usual ; abdomen longer than the head and thorax, finely and closely 

 punctured. Black, including the mandibles ; scape in part, two spots on pronotum, 

 tubercles, line on metanotum, sometimes wanting, greater part of anterior portion 

 of femora, and a line posteriorly, tips of medial pair, tibife except a variable spot 

 internally, and a spot on each side of dorsal abdominal segments 2 6, yellow. 

 Length 7 mm. 



Maine (Packard); Virginia, In the more strongly produced 

 basal joints of the flagellum this species approaches those of the 

 following group. It is a more elongate species than comigatus, and 

 the enclosing ridge of posterior face is feebler. 



3. Group nigrifrons. 



Body finely sculptured, particularly the abdomen, which is indis- 

 tinctly punctured ; dorsulum finely and closely .striato-punctate, 

 tending to closely punctured in the males ; mesopleurse delicately 

 and closely striated ; medial production of clypeus distinct, in the 

 males more so than in those of the preceding group ; flagellum of 

 <? with joints 1 and 2, or 1-4 very strongly produced or toothed 

 beneath, joints 1 and 2 solidified forming one long joint ; fore femora 

 (% ) not enlarged or produced at the base beneath, fore tarsi not 

 flattened, the first joint of medial tar.si armed within near the apex 

 with a tooth or spine ; last dorsal segment ( % ) not furrowed as 

 usual ; pubescence of front and clypeus ( 9 ) golden, silvery in the 

 males. 



11. Crabro obscurns Sm. 



Crabro ohscuras Smith, Cat. Hym. Brit. Mus., iv, p. 418, f % ■ 



Crabro denticulatm Packard, 1. c, p. 97, % . 



Crabro ob^curus Packard, ibid. p. 99, 9 • 



Crabro effosus Packard, ibid. p. 104, % . 



Crabro effosus Provancher, Hym. Queb., p. 660, 9 (^on % )■ 

 9 . — Head finely and closely punctured, first joint of flagellum fully as long as 

 the three following united ; space between hind ocelli about equal to that between 

 them and nearest eye-margin ; dorsulum finely and closely striato-punctate, the 

 scutellum more sparsely so ; mesopleurse more distinctly striated than the dor- 

 sulum ; upper surface of middle segment with coarse, somewhat oblique striations 

 and separated from the posterior face by a series of strong, transverse fovea, its 

 central furrow broad and transversely ridged, posterior face finely rugose, trans- 

 versely and more coarsely so on apical portion, rather distinctly ridged laterally, 

 sides with tolerably coarse striations. Black ; large spot on mandibles, scajie en- 

 tirely, base of pedicellum, two spots on pronotum, tubercles, metanotum, scutellum 



TKANS. AM. ENT. SOC. XXII. MAY. 1895. 



