78 ACADEMY OF NATURAL SCIENCES 



second segment with a transverse yellow band on the middle ; 

 third and fourth segments with a band and longitudinal line, 

 each side of which latter is a large transverse subtriangular spot, 

 yellow ; fifth segment with the yellow spots and base, but destitute 

 of the longitudinal line. 



Length about three-tenths of an inch. [89] 



2. S. OBLIQUA. — Thorax greenish bronze, with a yellow dot 

 before the wings ; tergum banded and spotted with yellow. 



Inhabits the United States. 



Head yellow, a dusky line above the antennae ; orbits yellow 

 to the vertex ; antennse blackish on the superior edge ; thorax 

 dark green-bronze, a large yellow spot before the wings ; scutel 

 bright-yellow ; feet whitish, anterior tibia and tarsi a little di- 

 lated, the latter with short joints, posterior thighs with one ob- 

 solete band and tibia two banded, extremity of all the tarsi 

 dusky ; tergum black, first segment with a yellow basal edge ; 

 second segment with a band at the base, interrupted into two ob- 

 long triangles, a broader one on its middle, yellow ; third seg- 

 ment with one band which is sometimes double ; fourth and fifth 

 segments each with an oblique oblong oval spot each side, and 

 two longitudinal lines on the middle, yellow. 



Length about three-tenths of an inch. 



Resembles the preceding, but there is no line upon the thorax, 

 and the markings of the tergum are different. 



3 S. CONCAVA. — Thorax bluish-green, tergum with four yel- 

 low bands. 



Inhabits Pennsylvania. 



Head whitish, sericeous ; antennae pale testaceous ; margin of 

 the mouth dusky; thorax bluish-green, with pale cinereous hairs; 

 scutel dusky, somewhat livid ; feet whitish, dull rufous at base ; 

 pectus dark glaucous, tergum black, quadrifasciate with yellow; 

 [ 90 ] first band interrupted, triangular each side, the others con- 

 cave behind, terminal one narrow. 



Length more than seven-twentieths of an inch. 



Very much resembles ^S'. rihesii of authors, but the second and 

 third bands of the tergum are widely concave behind, instead 

 of being almost acutely notched, as in the common European 

 species. I obtained several pupa; of this insect, adhering by the ' 



[Vol. III. 



