12 



DIPTERA. 



Femdle. Closely allied to M. mellinum. Face on the sides densely yellow-pollinose, leaving a median stripe 

 and the cheeks shining black, and extending on the front to an opaque black cross-band below the ocelli ; 

 the space immediately about the ocelli shining. Antennae yellow, the third joint blackish above. Meso- 

 notum brown, but little shining. Scutellum metallic greeu, shining. Abdomen subopaque, black,the first 

 segment somewhat shining ; second segment with a slender oblique spot, connected with the lateral 

 margin ; the third and fourth segments each with a pair of right-angled triangular spots, their apex 

 directed backward, and that of the fourth connected with the lateral margins, and the fifth segment 

 with a small triangular spot on each side in front, yellow. Legs yellow, the hind tarsi a little infuscated ; 

 hind metatarsi elongate, btit scarcely thickened. Wings tinged with yellowish, and narrowly, but 

 distinctly, clouded with blackish at the extremity. 



Length 7 millim. 



6. Melanostoma catabombum, sp. n., $ 2 . 



Male. Sides of the frontal triangle and of the face thickly covered with uniform yellow pollen, leaving a spot 

 in the middle above the antenna? and a broad median stripe below shining, somewhat metallic black ; 

 cheeks more or less shining. Antennaa red, the third joint largely blackish above ; first joint about as 

 long as the oval third joint, distinctly longer than the second. Frontal triangle with black pile. Meso- 

 notum and scutellum shining bronze, with yellowish pile ; pleurse of a similar colour in the middle, more 

 steel-blue below. Abdomen rather narrow, its greatest width at the distal end of the third segment j 

 opaque black ; the first segment and the hypopygium shining metallic ; second segment on the lateral 

 margin in front metallic ; third and fourth segments each with a pair of moderately large, rounded yellow 

 spots on the anterior part, touching the lateral margin ; pile along the sides anteriorly long and light 

 yellow. Legs yellow ; four front femora towards their base somcwhat brownish ; four front tarsi, except 

 part or all of the basal joint, blackish ; hind legs brown, the tarsi black, the base of the tibise and the 

 metatarsi yellow. Wings nearly hyalino ; the stigma brown, a narrow cloud at the tip in front blackish. 



Length 10-11 millim. 



Female. Front and sides of the face whitish-pollinose ; on the upper part of the former, below the ocelli, an 

 opaque black cross-band, with a point projecting downwards in tho middle. Thorax and scutellum mode- 

 rately shining, greenish-blue ; the mesonotum with three darker stripes, of which the median one is 

 linear. Abdomen subopaque, black, the first and last segments more shining ; the oval spots of the third 

 and fourth segments not touching the lateral margin ; the second segment with a yellow spot on each 

 side in front. 



Length 8-9 millim. 



Hah. Mexico, Omilteme 8000 feet, Amula 6000 feet, both in Guerrero (H. H. 

 Smith). 



Six males and three females. 



I am not quite sure that these females belong to the males here described, by 

 reason of their smaller size ; they agree structurally, however, throughout. 



7. Melanostoma crenulatum, sp. n., e $ . (Tab. I. %g. 5, $ ; 5 «, head in 



profile ; 5 b, head from in front.) 



Male. Allied to M. scitulum, Willist., but with the first joint of the antennas as long as the other two joiuts 

 together. Frontal triangle opaque black above, shining below, with black pile. Antenn® elongate slender 

 remote at their base ; first joint as long as the foUowing two joints together, yeUowish or 'reddish ■ 

 second and third joints of about equai length; third joint black, more than twiceas long as wide, obtusely 

 pointed. Tace shining black ; running from the inner side of each antenua, with a gentle outward curve. 

 to the oral margin, is a slender white line of pollen ; running transversely across the space contained 

 within these lines are three or four narrow, shallow, grooves ; three small spots of white pollen along the 

 orbital margin, the lowest one extended diffusely to the oral margin. Mesonotum moderately shining 



