OF PHILADELPHIA. 81 



the thighs and tibia arquated, the former blackish at tip, the 

 latter sub-bifasciate with brown ; tergum black ; first segments 

 yellow on the basal edge ; second segment with a yellow band on 

 the middle 3 third and fourth segments with each a central longi- 

 tudinal line, and two triangular spots on each side ; fifth segment 

 four spotted. 



Length about one-fifth of an inch. 



About equal in size to S. marginata S., from which it may be 

 known by its double lateral spots of the tergum, as well as bj 

 the absence of a yellow edging upon this part of the body. 



[Macquart has placed this as a new genus Toxomerus, describ- 

 ing it also as a new species, T. notatus Macq., Dipt. Exot. 5th 

 Supple. 93 ; tab. 5, fig. 4. — Sacken.] 



9. S. AFFiNis. — Thorax blued-black ', tergum black with three 

 yellow lunules on each side. 



Inhabits Arkansa. 



Head whitish, between the superior angles of the eyes black ; 

 antennae fuscous ; frontal elevation, superior oral angle, and pro- 

 boscis black ; thorax and pectus blued-blaek, with long dense 

 whitish hair each side; nervures testaceous; scutel pale testace- 

 ous ; feet whitish, dusky at base ; tergum black, with three lunules 

 on each side, and the two terminal segments edged with yellow; 

 venter yellowish, exterior edge and disks of the segments black. 



Length to the tip of the wings three-fifths of an inch. 



Size of S. transfuga Fabr., which it very closely [94] resem- 

 bles, and is to be distinguished by the somewhat darker coloring. 

 Is it not a variety of that species ? 



RHINGIA Fab. 



R. NASICA. % . — Tergum yellow, incisures and dorsal line 

 black. 



Inhabits the United States. 



Front yellow, beneath the mouth dusky; nasus prominent; 

 thorax bronze, with two obsolete cinereous lines on the anterior 

 margin ; scutel pale testaceous, a large brown spot on each side ; 

 feet pale yellowish, thighs dull red-bi*own at base, posterior tibia 

 in the middle and first joint of the tarsi dusky; tergum black, a 

 large transversely oblong quadrate yellow spot occupies each 

 1823.] 5 



