304 Mr. F. Walker's Characters of andescribed Dlptera 



Masicera expergita. 

 Mas. — Nigra, gracilis, capite albo, frontalibus angiistis atris, 

 antennarum articulo '6° longo, arista gracili, thorace siib- 

 cinereo, abdomine cylindrico maculis lateralibus albis, alis 

 nigricante cinereis, vena prsebrachiali angulum perobtusum 

 fingente, vend, transversa discali rectd. 

 Male. — Black, slender: head white; frontalia narrow, deep 

 black ; facialia without bristles ; epistoma not prominent ; an- 

 tennae nearly reacliing the epistoma; third joint slender, linear, 

 about four times the length of the second ; arista slender, stout at 

 the base, very much longer than the third joint ; thorax slightly 

 cinereous ; abdomen cylindrical, longer and a little narrower than 

 the thorax, bristly except towards the base, with white spots 

 along each side ; legs slender ; wings blackish-grey ; preebrachial 

 vein forming a very obtuse angle at its flexure, hardly curved 

 from thence to its tip, which is very little in front of the tip of 

 the wing ; discal transverse vein straight, parted by much less 

 Ihan its length from the border, and by very much more than its 

 length from the flexure, of the praebrachial ; alulae large, whitish. 

 Length of the body 2\ lines; of the wings 41 lines. 

 Mexico. 



Masfcera alacris. 



Fcem. — Nigra, cinereo-tonientosa, capite albo, frontalibus nigris, 

 antennarum articulo 2° rufescente, 3" longissitno, thorace 

 lineis quatuor nigris, abdomine ovato sub-tessellato, seg- 

 mentorum marginibus postjcis nigris, alis cinereis, alulis 

 albido-cinereis. 



Female. — Black, with cinereous tomentum : head shining white 

 in front and beneath ; frontalia black, narrow, linear, with lateral 

 bristles, which do not extend along the face ; facialia without 

 bristles ; epistoma not prominent ; eyes bare ; antennae nearly 

 reaching the epistoma; second joint reddish; third linear, about 

 four times the length of the second ; arista stout for about one- 

 fourth of the length from the base ; thorax with four slender black 

 lines ; abdomen oval, slightly tessellated, not longer than the 

 thorax ; hind borders of the segments black; wings grey; veins 

 black ; praebrachial vein forming a very obtuse angle at its 

 flexure, straight from thence to its tip ; discal transverse vein 

 undulating, parted by less than its length from the flexure of the 

 prsebrachial, and by much less than its length from the border; 

 alulae whitish-cinereous. 



Length of tlie body 3 lines ; of the wings 6 lines. 



Brazil. 



