126 MR. walker's catalogue OE DIPTEROUS insects 



Megistogaster, Macq. Mem. Soc. Sei. Nat. de Lille, 1850, 185. 



Body narrow, cylindrical, slightly setose. Face slightly retracted and ob- 

 lique ; epistoma not prominent ; facialia without bristles. Antennae very 

 long ; 3rd joint nearly linear, six times the length of the 2nd ; arista bare, 

 slender, a little longer than the 3rd joint. Legs setose, rather long. Wings 

 narrow ; prsebrachial vein forming an obtuse angle at its flexure, nearly 

 straight from thence to its tip, joining the costal at somewhat in front of 

 the tip of the wing ; discal transverse vein undulating, parted by about 

 half its length from the border and from the flexure of the prsebrachial. 

 Type. Tachina Diabolus, Wied. 



113. Megistogaster Imbrasus, Walk. Capt. Dipt. pt. 4. 781. ( Tachina.) 

 Inhabits also China.. 



The female has silvery- white tomentum in front of the head. 



Subfam. Dexides, Walk. 



Gren. Dexia, Meigen. 



114. Dexia munda, n. s., mas. Viridis, capite cano, frontalibus atris, oculis 

 nudis, antennis pedibusque nigris, abdomine nigro albo-tomentoso fasciis 

 duabus latissimis interruptis apiceque testaceis, alis fuscis, halteribus 

 testaceis. 



Male. Green, shining. Head with hoary tomentum in front and beneath, 

 and with gilded tomentum along the eyes above; frontalia deep black, 

 widening in front ; facialia without bristles ; epistoma not prominent. 

 Eyes bare. Proboscis and palpi testaceous. Antenna? black; 3rd joint 

 elongate ; arista pubescent. Pectus and sides of the thorax with whitish 

 tomentum. Abdomen black, shining, oblanceolate, about twice the length 

 of the thorax, armed with several very stout spines ; segments with whitish 

 reflections, and with two very broad interrupted testaceous bands; tip 

 testaceous. Legs black. Wings brown ; veins black ; prsebrachial vein 

 emitting a branch at its flexure which forms an almost right angle, from 

 whence it is indistinctly undulating to its tip, which joins the costal at 

 somewhat in front of the tip of the wing ; discal transverse vein undu- 

 lating, parted by less than half its length from the border, and by more 

 than half its length from the flexure of the prsebrachial. Alula? slightly 

 greyish. Halteres testaceous. Length of the body 6 lines ; of the wings 

 8 lines. 



115. Dexia extenders, n. s. (gen. Thelaira, Desv.), foem. Atra, capite 

 cano-tomentoso, vertice cervino, palpis antennisque ferrugineis, thorace 

 vittis tribus fasci&que testaceo-tomentosis, scutelli apice testaceo, abdomine 

 fasciis duabus latis albido-tomentosis, pedibus piceis, femoribus fulvis, alis 

 nigro-fuscis postice cinereis, halteribus fulvis. 



Female. Deep black. Head with hoary tomentum; vertex with fawn- 

 coloured tomentum ; frontalia broad ; epistoma, proboscis and palpi ferru- 

 ginous. Antennae ferruginous, much shorter than the face ; arista plumose. 

 Thorax with three stripes and one hinder band of testaceous tomentum ; 

 scutellum testaceous at the tip. Pectus with whitish tomentum. Abdomen 

 with some stout bristles, and with two broad bands of whitish tomentum, 



