154 HYMENOPTERA OF AMERICA. [PART I. 



firs! forming a little rugose crest; the trench of this last bordered 

 with trenchant and rugose ridges. Abdomen very slender; the 

 first segment lengthened, funnel-shaped ; its upper face as long 

 as wide, rather coarsely punctured, divided by an indistinct 

 groove; the suture strong, arcuate. The other segments smooth. 



Insect black. A spot at the summit of clypeus, another' 

 between the antennae, a dot behind each eye, two spots on the 

 prothorax, one below the wing, two on the scutellum, and the 

 border of segments 1, 2, 4, yellow. Tarsi ferruginous beneath; 

 tibia? marked with yellow at the summit; the anterior pair yel- 

 low. Wings transparent, a little washed with brown. Wing 

 scales black. 



Var. a. Spot on the clypeus very small, 



h. Clypeus wholly black. 



%. A little smaller. Clypeus, rounded and bidentate, pale 

 yellow; mandibles yellow before, bordered with black; a yellow 

 line on the scape of the antennae; extremity of the flagellum a 

 little ferruginous beneath. The yellow dots of the head and 

 thorax small ; that under the wing sometimes wanting. A yel- 

 low border upon the 5th segment. Tibiae yellow; tarsi yellow, 

 gray al the extremity. Groove of the first segment deeper. 



Bess. a. diff. — -This species greatly resembles the 0. sinuatus 

 Pabr., although its markings are less rich. But its first abdoini- 

 minal seginenl is much less coarsely punctured and the dividing 

 groove much less pronounced. It differs from the O.pumilus in 

 its much greater size, in its first segment being less rugose, and 

 in its different ornamentation; 



Eab. North America. Pennsylvania. New York. Canada. 

 Prairies. Fort Tejon. California. 6 ?, 1 %. 



3. S. albomarginatus Saoss. — Niger, punetatus; metanoto rugoso; 

 abdominis prhiio segmento grosse punctato, sutura elevata; puncto inter 

 antrnnas et frequenter altera in summo olypeo, maculis 2 proiroti, 2 

 soutelli, puncto subalari abdominisque segmentorum 1-4 marginibns, 

 albidis; til.iis albido-variis ; tarsis subtus ferrugineis. Alis byaliuis. 

 Longit, i) mm. 



Variat. Abdominis tertio segmento baud marginato. 

 Odi/nerus albomarginatus Sauss. Et. Vespides, III, 1854, 195, 90, $>. 



Hab. America borealis, Hudson's Hay. (Typus in AIus. Lon- 

 ilinensi.) Connecticut. (Ed. Norton.) 



