378 HYMENOrTERA OF AMERICA. [PARX 1 



utrinqne dente spiuiformi arraato, supra vix fisso, subdeuticulato ; 

 abdominis primo segmento tenuissime tlavo-marginato ; tarsis rufis ; 

 alia iufuscatis, costa obscuriore. 



Alastor singularis Sauss. Vespides, I, 259, 16, 9 (1852). 



Total length, 12 mm. ; wing, 9 mm. 



Closely allied to A. melanosoma; having the same form, but 

 jet differing by the following characters: — 



Head much swelled behind the eyes. The forehead not so 

 convex, nor parted by a groove ; no high carina between the 

 antennae, but rather an obsolete transverse wrinkle over their 

 base. Metathorax not quite so rough; its circular ridges making 

 nearly three-quarters of a circle : a little crenulate superiorly; its 

 inferior ridges straight, forming, at the meeting of the circular 

 ridge on each side, a distinct spine. 



Black; first abdominal segment narrowly margined with yellow r 

 or fulvous. Tarsi ferruginous. Wings washed with fuscous ; 

 dark along the anterior margin, transparent, smoky posteriorly ; 

 the reflection more golden than violet. 



Var. Second abdominal segment with a narrow submarginal 

 yellow line, anterior margin of pronotum with a very narrow 

 yellow margin (Rio). 



9. Clvpeus rather transverse, nearly lozenge-shaped, more 

 coarsely punctured, its apical margin truncate, not emarginate. 



Hab. Brazil (1 9 in my collection). 



Gen. SMITHIA Sauss. 



(Revue Zool. VII, 1855, 371.) 



Abdomen petiolate; the first segment contracted in its whole 

 length into a linear petiole. — Second cubital cell of the wing 

 petiolate. (Forms slender ; thorax elongate.) 



This genus is formed from the petiolate Alastor. It bears th \ 

 same relation to Alastor as Eumenes to Odynera*, as Ctenochihir 

 to Pterochilus. 



The only known species, Sin. naialcnxix Sans?, is from Soutli 

 Africa. The existence of this type in America has not yet been 

 pointed out. I mention it here only to complete the classifica- 

 tion of the solitary wasps. 



