80 ACADEMY OF NATURAL SCIENCES 



It requires some examination to perceive the difference be- 

 tween this insect and the S. corolla of Fabr., but on inspecting 

 the third and fourth segments of the tergum, it will be observed, 

 that there are at least two more bands on our species ; these bands 

 are narrow and are formed by the confluence of the yellow and 

 posterior edges of those segments with the yellow basal angles of 

 the succeeding segments. 



It is highly probable that the band on the middle [92] of the 

 fourth segment, and perhaps also that on the third are sometimes 

 entirely separated by their posterior emargination, each into two 

 oval spots. 



6. S. MARGINATA. — Tliorax blackish, with a yellow margin ; 

 tergum spotted, banded and edged with yellow. 

 Inhabits the United States. 



Head yellow, a blackish line above the anteneae ; thorax black- 

 ish, tinged with olivaceous or glaucous, a lateral yellow line con- 

 tinued to the scutel and an obsolete dorsal cinereous one ; scutel 

 yellow ; feet pale, posterior tarsi a little dusky at tip ; tergum 

 blackish, edged with yellow ; first segment with a yellow basal 

 edge ; second segment with a yellow band on the middle ; third 

 and fourth segments each with a dorsal line and somewhat ob- 

 lique spot each side confluent with the base yellow, sometimes 

 tinged with rufous ; fifth segment with two oblique yellow spots 

 confluent at tip. 



Length rather more than one-fifth of an inch. 

 This insect is smaller ;than the preceding ones, and may be 

 readily distinguished from them by the yellow abdominal edge, 

 as well as by the different arrangement of its spots. It is sub- 

 ject to vary in the character of its tergum, in having the spots 

 sometimes almost confluent with each other, or in being colored 

 with rufous. 



7. S. GEMiNATA. — Thorax with a yellow margin; tergum 

 spotted and banded with yellow. 

 Inhabits the United States. 



Head yellow silvery, at its junction with the thorax [93] 

 glaucous ; antennae yellow ; thorax bronze-blackish, a yellow line 

 each side, and an obsolete cinereous dorsal one ; scutel color of 

 the thorax, with a yellow margin : feet pale, posterior pair with 



[Vol. III. 



