204 Mr. F. Walker's Characters of undescrihed Diptera 



Uexiaf albicans. 



Mas. — Cano-tomentosa, capite subalbo, frontalibus ferrugineis, 



palpis testaceis, antennis nigris, articulo 2° testaceo, tliorace 



abdomineque cinereo-trivittatis, abdomine subfusiformi, pedi- 



bus robustis, alis vix subcinereis, venis testaceis apice nigris, 



alulis albis. 



Male. — Thickly covered with hoary tomentum ; head almost 



white, rather prominent ; frontalia ferruginous, linear ; facialia 



without bristles ; epistoma not prominent ; eyes remote ; palpi 



testaceous ; antennae black, third joint not reaching the epistoma, 



more than twice the length of the second, which is testaceous ; 



thorax and abdomen with three slight cinereous stripes; abdomen 



subfusiform, longer than the thorax ; legs stout ; wings hardly 



greyish ; veins testaceous, black towards the tips ; prat'brachial 



vein forming an almost right angle at its flexure, near which it is 



curved inward, straight from thence to its tip, which ends at 



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



nearly straight, parted by much less than its length from the 



border and from the flexure of the praebrachial ; alulae white. 



Length of the body 4 lines ; of the wings 7 lines. 



Valley of the Amazon. 



This species may perhaps form a new genus on account of the 

 shape of its head and of its thick legs. 



Dexia spinosa. 



Mas. — Nigra, cinereo-tomentosa, capite testaceo albido tomentoso 



antice subproducto et subcompresso, frontalibus ferrugineis, 



palpis antennisque testaceis, thorace vittis tribus nigris, 



pectore cano, abdomine testaceo oblanceolato, vitta dorsali 



apiceque nigris, pedibus perlongis, femoribus testaceis, alis 



fusco-cinereis, venis nigris, alulis cinereis testaceo marginatis. 



Male. — Black, with cinereous tomentum ; head with whitish 



tomentum, testaceous in front and beneath, slightly prominent 



and compressed in front of the eyes ; frontalia ferruginous, 



widening in front, with a thick row of bristles on each side ; 



face with a furrow along each side ; facialia without bristles ; 



epistoma not prominent ; eyes bare ; proboscis rather long ; 



palpi testaceous ; antennae testaceous ; third joint not near 



reaching the epistoma, full twice the length of the second ; thorax 



with three black stripes ; pectus hoary ; abdomen testaceous, 



oblanceolate, much longer than the thorax, with black spines, 



which are mostly towards the tip ; dorsal stripe and tip black ; 



