84 CHARLES ROBERTSON. 



Black, pubescence short and glittering, more dense and whitish on face. Man- 

 dibes, except tips, interrupted line on prothorax, tubercles, spot on tegulfe, spot 

 on squama, 8-10 elongated spots on abdomen, yellow; flagellum black, paler at 

 tip; tegulse testaceous. Legs black, anterior tibise and tarsi dull honey-yellow. 

 Apical segment of abdomen rufous. Wings hyaline, nervures dark. 



% . — Resembles the female, a little more coarsely punctured, the sculpture of 

 face sometimes poorly defined, abdomen with four or tive strong lateral spines 

 scape in front more or less, anterior and middle femora at tips beneath extending 

 more or less towards base, tibise exteriorly, and tarsi yellow, the latter sometimes 

 brown. The abdomen has five pairs of narrow spots, those on fifth segment 

 sometimes forming a continuous line. Ajjex of sixth segment and all of seventh 

 rufous, the sixth sometimes with yellow liand. Length 9.5-6 mm. ; % , 4-6 mm. 



Pennsylvania, Illinois, Texas. Twenty-seven females, forty males 

 (coll. Am. Eat. Soc. and C. R.). 



Resembles 0. emargiiiatus, but easily distinguished by sculpture 

 of front, the narrower spine, the darker legs of female and 10-spotted 

 abdomen of male. 



The commonest species in my neighborhood ; I have taken it from 

 June 7th to August 18th on flowers of Eulophus, Pastinaca, Cicuta, 

 8ium, Eryngium (Umbellifene), Pycnanthemum (Labiatse) and 

 Asclepias verticillata (Asclepiadacese\ 



13. Oxybelii»« einar^inatus Say. 



0. ema7-ginatus Say, Bost. Jouru. Nat. Hist, i, 375. 

 O. parvus Cre.ss , Proc. Ent. Soc. Phil, iv, 476, % . 



9. — Densely punctured; prothorax carinate ; scutellum and postscutellum 

 with a central longitudinal caiina ; squama large, ovate. Spine broad, square^ 

 hollowed above, broadly furcate at tip; base of metathorax with few radiating 

 striffi. Abdomen closely punctured ; basal segment with a median depression. 

 Black, pube.scence silvery on face. Mandibles, except tips, sides of prothorax, 

 tubercles, two small remote spots on scutellum sometimes wanting, pale yellow . 

 flagellum testaceous beneath. Wing scales and extreme base of wing reddish 

 testaceous. Abdomen with four to eight elongated yellow spots on the sides ; 

 the fifth segment is black, or partly or wholly rufous; in one specimen from 

 Montana the fifth segment is black, with two yellow spots, making the abdomen 

 10 spotted ; apical segment rufous. Legs black: the anterior femoi-a at tips be- 

 neath extending more or less towards base yellow, the middle like the anterior, 

 or sometimes entirely black; anterior tibise and tarsi, two hinder pairs of tibise 

 at base exteriorly extending more or less towards tips, yellow. Wings hyaline, 

 nervures dull ferruginous. 



Yar. 9- — Scutellum hardly carinate; prothorax, scutellum and tubercles 

 black; middle tibiae yellow in front; tegulse darker than in the common forms 

 (Nevada). 



'^ . — Resembles the female; a little more strongly punctured. Abdomen with 

 two or three lateral spines; scutellum black; prothorax and tubercles black, or 

 with a littJe yellow ; all tibiae yellow to tips exteriorly ; tarsi generally all yellow. 



