30 HYMENOPTERA OF AMERICA. [PART I. 



rior border armed with two little distant teeth. Head extremely- 

 dilated at the vertex, strongly excavated behind, wider than the 

 thorax. Thorax very short, not being one and a half times 

 longer than wide. Prothorax slightly retracted before, its ante- 

 rior margin bordered by a sharp projection, which forms on each 

 side an indistinct angle. Mesothorax carrying on its posterior 

 part four longitudinal furrows, and upon its anterior part one 

 middle groove. Scutellum divided by a sinus. Metathorax 

 offering a feeble concavity, wrinkled and striate. Petiole moder- 

 ately short, its expansion globular, having almost the same form 

 as in the Z. coeruleipennia, but less contracted behind and trun- 

 cate ; the second segment globular-ovate, but depressed. 



Insect black, polished and shining. The metathorax garnished 

 with a grayish pile. Clypeus, head, thorax, and petiole densely 

 cribrose with great punctures: this last earning near its terminal 

 border a large sunken place. Abdomen sown with finer punctures, 

 sometimes very fine. There is often a slight depression toward 

 the middle of the border of the second segment. A frontal dot at 

 the insertion of each of the antennae, the border of the prothorax 

 or only two spots upon the shoulders, often a spot below the 

 wing, a band or two spots upon the scutellum and the anterior 

 border of the post-scutel, and also two spots at bottom of the 

 metathorax, of a pale yellow. Margin of the petiole, and a 

 narrow border along the margin of the second segment, of the 

 same color. Feet black. Wings brown, with violet reflections. 

 %. Smaller. Clypeus wide, moderately rounded, not having 

 a lozenge shape, its inferior border straight, hardly bituberculate. 

 This part either wholly or only in its inferior moiety, whitish. 

 The scape of the antenna before, is ornamented with a whitish 

 mark ; the terminal hook black ; on the face is often a little 

 yellow dot at the side of the insertion of each of the antennas. 

 The third abdominal segment is often adorned with a whitish 

 border. This is the E. substricta Hald. The female presents 

 the same variations. 



Var. a. Scutels, prothorax, and two great spots on the meta- 

 thorax yellow (Z. variegatus, bicolor). 



b. Often the scutels have hardly any spots, and the second 

 segment is scarcely edged with pale yellow (Z. subst?nctus). 

 Markings sometimes ferruginous. 



c. Certain specimens are entirely black, with a little yellow 



