ADAMS : DIPTERA AFRICANA. 207 



perceptible in the perfect specimens; two rows of dorsocentrals, 

 each with two bristles in front of and three behind the suture, 

 two humerals, two posthumerals, one supraalar, and one 

 postalar, the prescutellar bristles mark the termination of two 

 rows of small bristles on dorsum of mesonotum ; four meso- 

 pleural and four sternopleural bristles present, two of the latter 

 situated low down ; scutellum with ah apical, a preapical, and 

 a basal pair of bristles ; halteres yellow. Abdomen yellow, a 

 triangular spot on posterior margin of second, and the third and 

 fourth segments largely, black, in certain lights all segments 

 silvery pollinose on posterior border. Legs yellow, tarsi black, 

 pulvilli yellow. Wings yellowish. Length, 5 mm. 

 Two specimens ; April. 



CCENOSIA. 

 (Meigen, Syst. Beschr.. V, 210; 1826.) 



Ccenosia valida, n. sp. 



Male and female : Head yellow, occiput black, with gray 

 pollen, frontal vitta velvety brown, yellow on lower third ; first 

 two antennal joints yellow, third black, reaching almost to the 

 oral margin, arista black, bare; proboscis short, black, palpi 

 yellow ; five frontal bristles, an inner and an outer vertical 

 bristle present, ocellar bristles directed forward. Thorax black, 

 with gray pollen, humeri and lower part of pleurae yellowish ; 

 bristles on mesonotum short and not easily differentiated from 

 the bristly hairs ; I can definitely see three humeral, two post- 

 humeral, one supraalar, one postalar, one dorsocentral on hind 

 border, and a pair of small prescutellar bristles ; there are three 

 mesopleural and three sternopleurals, one of the latter situated 

 low down ; besides an apical and a basal pair, there is a pair of 

 small preapical bristles on the scutellum. Abdomen yellow, in 

 the male the third and fourth segments, and in the female the 

 fourth, bimaculate. Legs yellow, in the male the apical fourth, 

 and in the female the apical two-thirds, of the front femora black, 

 the front tibi«?, except the basal fourth, and all tarsi blackish. 

 Wings hyaline, veins semitranslucent. Halteres yellow. Length: 

 Male, 3 mm. ; female, 4.5 mm. 



Ten specimens ; February and April. 



