422 MEMOIRS OF THE CARNEGIE MUSEUM 



Thorax above wholly red, the pleura and metathorax black ; head black ; scape, front and middle 

 legs and the abdomen at base pale yellowish ; hind legs, except tarsi, pale ferruginous, $ . 



S. flavobasalia. 



11. Thorax above mostly black, without small yellow or reddish dots, the lobes margined with yellow.. 12 

 Thorax above mostly black, but the dorsum with many small yellow or reddish dots. 



Legs mostly black, the knees of front and middle legs, the base and apex of tibise, and all tarsi, 

 yellow ; abdomen black with two transverse white lines at apex of the second dorsal seg- 

 ment, 9 <S'. janeiroensis. 



12. Hind coxte mostly black or black ivith yellow stripes 13 



Hind coxae not mostly black ; mesothoracic lobes margined with yellow 15 



13. Hind coxa; ivilh a yellow spot at base above or striped black and yellow 14 



Hind coxae without a yellow spot at base. Head, except the front orbits, black ; thorax black with a 



line on each side of the middle mesothoracic lobe and two large spots on the scutellum, yellow ; 

 hind femora with a spot at apex, the front and middle legs except the coxae, the hiud tarsi and the 

 petiole of the abdomen, yellow, i .S'. santaremensis. 



14. Vertex with no irregular yellow marks, otherwise similar to S. flavopetiolata, except that the scutellum 



has two oblong yellow spots, one on each side, the metanotum and the mesopleura being im- 

 maculate 16 



Vertex with irregular yellow marks, or the ocelli margined with yellow ; front orbits, clypeus, a line on 

 each side of the middle mesothoracic lobe, a spot on the lateral lobes, two oblong spots at base of 

 scutellum nearly confluent, two spots on metanotum, a spot on mesopleura beneath the tegulse and 

 a small spot in front of it, and the legs, except the coxae, the base of front and middle femora 

 beneath, and most of hind legs which are black, yellow ; the hind coxae have a yellow spot at base 

 above connected with a long yellow stripe beneath ; hind femora margined with yellow at base and 

 above, and also with a yellow spot outwardly near the apex ; hiud tibiae with a yellow line outwardly 

 extending from near the base to the apex S. flavoorbitalis. 



15. Front wings maculate, or with a fuscous spot or cloud from the tip of the stigmal vein 16 



Front wings immaculate, or without a fuscous spot or cloud from the tip of the stigmal vein 21 



16. Head not entirely yellow, the occiput and the scrobes or the middle of the face black 17 



Head entirely yellow 20 



17. Scutellum mostly yellow with a central black spot ; if black margined with yellow, the axilhe never 



wholly black, the ridge or plate at apex entire 18 



Scutellum mostly black with two large yellow spots nearly confluent at apex, the axilla- wholly black, 

 the ridge at apex emarginate ; front and middle legs yellow, $ S. persimilis. 



18. All legs entirely yellow, except a spot, sometimes faint or nearly obsolete, on hind coxae above. ... 19 

 Front and middle legs entirely yellow, the hind legs marked with black, the coxae more or less black 



above, $ S. unimaculata. 



19. Abdomen fusiformly pointed and yellow, except the sheaths of the ovipositor which are black. 



All mesothoracic lobes black margined with yellow ; scutellum yellow with a large central black 

 spot ; mesopleural furrow black ; hind coxae with a distinct black spot, ? S. perplexa. 



Not all of the mesothoracic lobes black margined witli yellow, the lateral lobes being wholly 

 yellow ; spot on hind coxae nearly obsolete, ? -S'. imitator. 



20. Thorax mostly yellow with the sutures, a median stripe or line on the middle mesothoracic lobe pos- 



teriorly and on the scutellum, black ; all legs yellow ; abdomen as in S. imitator, $ <S. simillima. 



Thorax mostly yellow but with the middle mesothoracic lobe anteriorly and the tip of the metathorax 



