ODYNERUS. , 1 53 



Bess. a. diff. — This species differs from the 0. Philadelphia 

 in its greater size, its more complete marking, the 3d segment 

 of the abdomen being bordered with yellow ; in its yellow wing 

 scales, tibiae, and tarsi, in its thorax, less lengthened, and not 

 bidentate upon its anterior angles ; in a slightly different punc- 

 turation. 



One could say that the 0. Walshianiis is the American repre- 

 sentative of the 0. gracilis Wesm., an entirely corresponding 

 species of Europe, although smaller, and more ornamented with 

 yellow, having a more slender thorax and a bidentate prothorax. 



The 0. Walshianus is quite intermediate between the 0. cras- 

 sicornis and the 0. gracilis, both in the forms and size, but its 

 yellow markings are less extended, as may be observed in general 

 of the American species. 



It differs from the 0. pumilus in its greater size, in its less 

 slender form, in its prothorax which is not bidentate, in its first 

 abdominal segment which has the superior face twice as wide as 

 long, etc. 



Hob. The United States. Illinois. 



I possess but one female, sent by Mr. Benj. D. Walsh, to whom 

 I dedicate the species. 



b. Segments 1, 3, 4 of the abdomen bordered loith yellow. 



2. S. Pliiladelpliiae Sauss. — Niger, punctatus, gracilior, post-scutello 

 et metanoto rugosis ; abdominis primo segmento valde punctato ; reliquis 

 nitidis; puncto frontali et post-oculari. maculis 2 pronoti, macula snb- 

 alari, maculis 2 scutelli et abdominis segmentorum 1', 2', 4> limbo, fiavis ; 

 tegulis nigris; tibiis flavo-variis. 



9- Clypeo uigro frequenter macula flava; %. Clypeo flavo, rnandibulis, 

 linea in scapo autennarum, et 5 1 segmeuti limbo, fiavis. 



Odijn. Philadelphiee Sauss. Revue Zool., IX, 1857, 272. 



Total length, 11 mm. ; wing, 8.5 mm. 



9 . In form very slender and lengthened. Clypeus rounded, 

 convex, punctate, hollowed, and distinctly bidentate. Thorax 

 mvm lengthened ; prothorax rimmed, its angles a little salient : 

 mesothorax traversed in its whole length by two strong grooves; 

 its anterior part punctured, like the prothorax; the remainder of 

 the disk smooth, finely punctured ; scutellum smooth, divided by 

 a large groove; post-scutel and metathorax very rugose; the 



