DIPTERA. 83 
clothed with short pale hairs: sucker black, clothed with pale tawny hairs : 
first and second joints of the feelers black; second not half the length of 
the first: chest clothed with tawny hairs: abdomen slightly increasing in 
breadth from the base till near the tip, longer, but hardly broader than the 
chest, ferruginous towards the tip, clothed with tawny hairs, which form 
bands on the hind borders of the segments: legs black, covered with yel- 
low down ; hind shanks towards the base and feet yellow; claws black : 
wings dark gray, tawny beneath the fore border for three-fourths of the 
length from the base ; wing-vibs and veins ferruginous ; veins black in the 
gray parts of the wing; poisers tawny. Length of the body 54 lines; of 
the wings 12 lines. 
Columbia. 
Genus SARGUS, Meigen. 
Sarcus DEBILIS, Mas. 
Viridis, capitis macula flava, thoracis disco purpureo-cyaneo, scutelli apice 
purpureo, abdomine fulvo apice subaenceo, antennis pedibusque fulvis, 
alis limpidis. 
Body bright green: head yellow and clothed with pale yellow hairs 
at the base of the feelers: eyes pitchy ; facets small, somewhat larger in 
front than elsewhere: mouth pale tawny : feelers tawny ; bristle pitchy : 
disk of the chest purplish-blue ; tip of the scutcheon purple: abdomen 
pale tawny, longer than the chest, increasing in breadth from the base 
towards the tip, where the disks of the segments are more or less bronzed : 
legs pale tawny: wings colourless ; wing-ribs tawny ; veins pitchy, tawny 
at the base and along the fore border; poisers tawny. Length of the body 
4 lines ; of the wings 8 limes. 
United States. 
CACOSIS, n. g. 
Antennis articulus 3us longus ; seta basi crassa, nigro pubescens. 
Third joint of the feelers longer than that of S. Vespertilio ; bristle 
thick and clothed beneath towards the base with black down. 
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