358 ACADEMY OF NATURAL SCIENCES 



polished, naked line : antennae piceous : front covered by yellow 

 hair : thorax densely covered by yellow hair black in the middle : 

 scutel piceous, covered by yellow hair : wings with a large 

 fuscous spot on the middle, obsolete in the male : poisers 

 piceous : tergum black, covered by black hair; basal segment 

 and second segment at base covered by yellow hair : feet hairy ; 

 tarsi piceous : posterior thighs of the male much thickened and 

 with their tibiae arquated. 



Length three-fifths of an inch. 



This I formerly considered as Eristalis posticatus Fabr., but 

 his attributed characters of " thorax inimaculatus " and '* femo- 

 ribus posticis dentatis " seem to prove it distinct. 



[Walker, List of Diptera of British Museum, 3, 598, refers 

 this species to Merodon. — Sacken.] 



SYRPHUS Fabr. Meig. 



1. S. stegnus. — Blackish-blue; tergum fasciate with glau- 

 cous. [164] 



Inhabits Mexico. 



Body black-blue : hypostoma with dull cinereous irregular 

 rugosities : antennae, terminal joint beneath dull honey-yellow : 

 wings hyaline, between the mediastinal and postcostal nervures 

 yellowish : poisers yellow : tergum velvet black, opake, with 

 polished glaucous bands, the first one interrupted; second and 

 third occupying the basal half of the segments, the outer margin 

 and the narrow tip, together with a longitudinal line ; terminal 

 segment entirely glaucous : tibiae honey-yellow : venter cupreous. 



Length less than three-tenths of an inch. 



2. S. MUTUUg. — Tergum yellow, with blackish bands and 

 spots. 



Inhabits Mexico. 



Head beneath and behind plumbeous : posterior orbits dull yel- 

 lowish : front and vertex brassy black : hypostoma prominent, 

 yellow : antennae, beneath honey-yellow : thorax olivaceous, with 

 a blue vitta, and yellow one over the wings : scutel dull yellow- 

 ish, paler at tip : tergum with five broad blackish-purple bands, 

 concealing the incisures, and on the middle of the third and 

 fourth segments are two small blackish spots ; terminal band 



[Vol. VI. 



