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’ ‘ + ~ : . 
DIPTERA. 317 
ferruginous ; feet black: wings gray, yellow at the base and along three- 
fourths of the fore border, brownish at the tips and along the veins; veins 
tawny, brown towards the tips, prebrachial vein forming a curve at its 
flexure, straight from thence till near the tip where it is slightly bent in- 
ward, lower cross-vein hardly bent inward towards the tip: alule and 
halteres pale yellow. Length of the body 4} lines ; of the wings 8 lines. 
Amazon River. 
Dexia surrusa, Fem. 
Nigra, subaurata ; caput album ; abdomen fulvum, apice nigrum ; an- 
tenne fulve; pedes fulvi, tarsis nigris; ale subcineree, basi et ad 
costam subfulve. 
Black, with a slightly gilded covering : head with a snow-white covering 
in front ; frontalia black, linear; facialia without bristles; epistoma not 
prominent; palpi tawny : feelers tawny ; third joint mostly darker, linear, 
rounded at the tip, not reaching the epistoma, more than twice the length 
of the second ; sixth black, feathered to the tip with short hairs, more than 
twice the length of the third: abdomen tawny, obconical, longer than the chest, 
with a few black spines, black towards the tip : legs tawny ; shanks darker 
than the thighs; feet black: wings slightly gray, with a tawny tinge at the 
base and along the veins and on part of the fore border which has a pale brown 
tinge towards the tip ; veins tawny, pitchy towards the tips ; prebrachial vein 
forming a curve at its flexure, almost straight from thence to its tip ; lower 
cross-vein with a very slight inward curve near the base, and a more in- 
distinet outward curve in the middle: alule and halteres yellow. Length 
of the body 3} lines; of the wings 7 lines. 
DExXIA ALBIFRONS, Mas. 
Cinerea ; caput album ; thorax nigro quadrivittatus ; antenne nigra, basi 
rufa; pedes nigri, tarsis ferrugineis ; ale cinerea, basi subfusce. 
Black, with a cinereous covering : head with a white covering ; frontalia 
black, with a ferruginous disk, widening from the eyelets to the feelers } 
facialia without bristles; epistoma tawny, prominent; lateralia ferruginous ; 
peristoma ferruginous, prominent: mouth black, nearly as long as the 
chest, tawny at the base ; palpi yellow, long, slender: feelers black; first 
2T 
