38 DIPTERA. 



than twice as long as broad. Legs yellow ; the hind femora, except the tip, and the hind tibiae, except tbe 

 base and tip, brown. Wings subhyaline ; the subcostal ceE beyond the auxUiary vein brown ; the distal 

 part of the wing, especially before the third vein, clouded with blackish. 

 Longth 10-12 millim. 



Hab. Mexico, Sierra de las Aguas Escondidas in Guerrero 9500 feet (H. H. Smith). 

 Two specimens. 



16. Baccha ccerulea, sp. n., $ $ . 



Female. Deep steel-blue, shining. Pront moderately narrowed above, the vertex shining purple, this colour 

 extending down as a slenclcr median stripe ; front elsewhere lighter metaliic blue ; pile black. Face 

 bluish-black, with whitish dust ; a small red spot on the sides below. Antennce brownish-red ; third joint 

 a little longer than wide, broadly black above. Mesonotum bluish-black, feebly striped. Pleurae with 

 white pile. Abdomen only a little narrowed towards the base, the second and third segments of about 

 equal length and about as broad as long ; second segment with a semilunar cross-band, and the third and 

 fourth segments each with a pair of large triangular spots, separated by a line, opaque blaek ; dorsum with 

 sparse, white, short, curved hairs. Wings hyaline ; a narrow dark brown border extending from the base 

 to the tip of the costal vein, a little broader in the submarginal cell, and with a slight projection at the 

 origin of the third vein ; the costal cell lightcr-coloured. Legs : femora black or dark brown, thcir tips or 

 distal parts and the four anterior tibioe and the metatarsi brownish-yellow, the tarsi, otherwise, aud the 

 hind tibiae brown ; hind metatarsi lighter yellow, elongate and but slightly thickened. 



Male. Eyes with the facets much larger above, a horizontal line near the middle. Frontal trianglc somewhat 

 bronze-coloured in the middle ; pilc black. Pacc without the red spot on the sides below. Mesonotum 

 more brownish or bronze-eolourcd. Band of the second abdominal segment larger; the remainder of the 

 abdomen opaque, save the narrow margins of the segments. 



Length 7-9 millim. 



Hab. Mexico, Amula 6000 feet, Xucumanatlan 7000 feet, Omilteme 8000 feet, and 

 Sierra de las Aguas Escondidas 9500 feet, all in Guerrero (H. H. Smith). 



Four specimens. 



17. Baccha concinna, sp. n., <j $ . 



Pront of the female much narrowed above, shining blue-black. whitish-pollinose, shining black below. Pace 

 narrow, blue-black, the orbital margins narrowly yellow, whitish-pollinose. Antenna? red ; third joint 

 short ovate, obtusely pointed, black above. Prontal triangle blue-black, thinly pollinoso. Mesonotum of 

 the male deep blackish-brown, more shining bluish on the lateral margins : mesonotum of the female 

 more shining blue, with two or four narrow brown stripes in front. Scutellum coloured like the meso- 

 notum. Pleurse more shining blue. Abdomen moderately narrowed at the base, not slender— in the 

 male opaque blaek, with the first segment, the broad auterior angles of the second, third, and fourth 

 scgments, and the fifth segment and small hypopygium shining blue-black ; in the female the opaque 

 black forms a subtriangular spot on the second segment, a larger triangular one on the third, three spots 

 on the fourth, and two or three streaks on the fifth. Legs blackish ; the tip or distal part of the femora 

 and the base of the hind tibise yellow, the four anterior tarsi and the distal part of the four anterior tibi® 

 somewhat brownish-yellow ; hind tarsi of the male, except the basal two thirds of the metatarsi, yellow. 

 Wings hyaline or nearly so ; in the male with the costal, subcostal, and the baeal part of the niarginal 

 cells yellowish-brown ; in the female with the subcostal cell only brown. 

 Length 8-9 millim. 



Hab. Mexico, Chilpancingo 4600 feet and Venta de Zopilote 2800 feet, both in 

 , Guerrero, Teapa in Tabasco (H. H. Smith). 



