ADAMS : DIPTERA AFRICANA. . 187 



Drosophila mutabilis, n. sp. 



Male and female : Yellow, in certain lights the entire body 

 is sericeous ; front with parallel sides, sometimes the sides only- 

 show silvery, two verticals and three fronto-orbitals on each 

 side ; the upper one of the latter is nearly opposite the lower 

 ocellus and directed backward ; the other two are very close 

 together, nearly half-way between ocelli and antennse, directed 

 backward and forward respectively ; ocellar bristles small ; face 

 scarcely broader than the front, slightly excavated, orbits nar- 

 row ; antennDP about three-fourths as long as the face, third 

 joint elongate-oval, arista with seven pectinations above and 

 three below; proboscis fleshy, palpi linear, with a few apical 

 bristles ; cheeks narrow. Mesonotum with very short black 

 pile, a humeral, two posthuraeral, one supraalar, and one 

 postalar bristle ; scutellum with the posterior border somewhat 

 oval, and with an apical pair of bristles ; pleurse with a pair of 

 sternopleural bristles ; halteres yellow, sometimes with black- 

 ish knobs. Abdomen yellow, with considerable variation, in 

 either sex, as to the black markings ; some specimens show two 

 large lateral, and one small central spot on fourth segment, 

 and three small ones on fifth segment ; others agree with the 

 foregoing with the addition of two sublateral spots on the 

 second segment ; others agree with the first set with the ad- 

 dition of a large central spot on the third, and a small central 

 one on the sixth segment ; others have the abdomen wholly 

 yellow, and one specimen has the third and fourth segments 

 wholly black. Legs yellow, front femora with from three to 

 four strong bristles on under side. Wings hyaline, costa 

 reaches tip of third vein ; the female usually has a small dot at 

 tip of first vein, the male wing as follows : Near the base there 

 is a prominent black spot reaching from costa to fifth vein, the 

 small cross vein is narrowly surrounded by brown ; just proxi- 

 mad to the tip of the second vein is a large quadrate spot 

 reaching to the third vein, then it narrows and crosses the first 

 posterior cell to join a large subquadrate spot around the hind 

 cross-vein ; the latter spot attains the wing margin just beyond 

 the tip of the fifth vein ; the angle between the third vein and 

 the costa is filled out half-way to the tip of the second vein ; in 

 the second posterior cell and near tip of fourth vein is a tinge 

 of brown, the apex of the first posterior cell, the base of the 



