Osten Sacken.] 146 [October 6, 



one posteriorly; the former almost touches the margin of the abdo- 

 men. The third band is similar to the second, only its hind margin 

 is more perceptibly arcuated. The posterior margin of the fourth 

 segment has, as usual, a narrow yellow border, the fifth likewise, 

 and two yellow spots at the base besides. Femora yellow; the four 

 anterior ones in some specimens brownish at the extreme base only; 

 the hind pair with a more or less distinct brown ring on the distal 

 half ; four anterior tibiae and tarsi yellow ; the hind tibiae sometimes 

 with a brownish ring, hind tarsi brownish. 



Length, 9-10 mm. 



Male. Front yellow, with a more or less distinct brown spot 

 above each antenna; crossbands on the abdomen broader than in the 

 female, and distinctly broader than the black interval between them ; 

 posteriorly, they are often nearly straight, sometimes distinctly arcu- 

 ate, especially the third band. The yellow spots on the second seg- 

 ment are not coalescent, but separated by a narrow black interval 

 (in some species subcoalescent) ; the fifth segment is yellow, with a 

 black spot in the middle. The four anterior femora are black at the 

 base ; the hind femora are usually black, with a yellow tip ; some- 

 times there is a trace of yellow at the base ; hind tibiae usually with 

 a brown ring in the middle. 



Length, about 9 mm. 



Hob. British Possessions, New England, New York, Delaware, 

 Virginia. In Detroit, Mich., in August, I found this to be the most 

 common species. It seems also to be common in Texas (Waco, 

 Texas; Belfrage). Sixteen males and eight females. 



S. americanus ?, diners from S. abbrevlatus, ?, besides being larger, 

 in the presence of a brown stripe in the face, and of brown spots 

 above the antennae; in the spots of the seeond segment being alto- 

 gether coalescent (instead of narrowly interrupted) ; in the eross- 

 bands not touching (or hardly touching) the abdominal margin, 

 while in S. abhreviatus the contact is broad and distinct; in the 

 crossbands being (in most specimens) more straight, less sinuate 

 posteriorly. 



S. americanus d, differs from S. abbreviatus <?, besides being 

 larger, by the brown stripe on the face, the more straight seeond 

 crossband (less sinuate posteriorly) and by the coloring of the hind 

 femora. In those specimens of S. americanus which have the hind 

 femora altogether blackish, the yellow space at the tip is narrower 

 than the yellow space in ordinary -specimens of S . abbreviates, d. 



