246 A. L. MELANDER. 



3. Legs wholly yellow seqiiens uoiu. nov. 



Legs in part dark brown to black 4. 



4. Halteres yellow 5. 



Halteres infuscated 7. 



5. Wings hyaline 6. 



Wings gray, though hyaline at base reversus Walker. 



6. Legs wholly black ty pious Wh. et Mel. 



Tibiffi and tarsi more or less yellow slossonse Coquillett. 



7. Stigmal spot noticeable 8. 



Stigmal spot obsolete triplex Walker, varieties. 



8. Wings completely hyaline 9. 



Wings more or less infumated basally 10. 



9. Tibise black inellipes Wh. et Met. 



Tibiae fulvous ; size smaller electus var. 



10. Thorax and abdomen with bluish reflections electus uom. nov. 



Thorax and abdomen black triple^ Walker, varieties. 



Hybos typiciis* Wheeler et Melander. 

 Biol. Cent.-Am. Dipt. Suppl., 1901. 



Black cinereous, slender. Antennae black, short; third joint oval, not longer 

 than the first. Eyes contiguous below anteunse. Proboscis black. Thorax 

 prominent, black, shining through the coating of brown dust; pleurae cinereous- 

 black. Halteres yellow. Abdomen slender, piceous, slightly pubescent, espe- 

 cially towards apex. Genital apparatus of male small, not giving the abdomen a 

 club-shape, with two projecting filaments. Legs slender, piceous, shining, with 

 scattered pubescence, knees lighter, front tarsi long, metatarsus equal to the 

 tibia, middle tibiae with two long slender bristles on the external side at basal 

 fourth and half, and three on inner side at half, three-fourths and tip; hind 

 femora not much thickened, not evidently serrate beneath, besides the pubescence 

 a series of about six hairs beneath ; hind tarsi not toothed beneath. Wings hya- 

 line, subquadrate, obtusely rounded at apex, anal angle not strong, veins yellow- 

 ish ; third vein terminates beyond the middle, parallel with the fourth ; stigmal 

 spot not well developed, not filling out the apex of the marginal cell ; discal cell 

 broad ; anal vein not evident. The fine hairs around the margin of the wing 

 are not so closely placed as usual. 4.5 mm. 



The males have the front legs sparsely ciliate with long hairs ; 

 the tibiae on the posterior side and the metatarsi on both sides. 

 Guerrero, Mexico (H. H. Smith). 



Hybos spinicosta Wheeler et Melander (Fig. 77). 

 Biol. Cent.-Am., 1901, Dipt. Suppl., p. 374. 



Differing from typicus as follows : — Face narrower, dusted with silvery-white 

 instead of gray. Legs wholly pitchy-black ; the tibial and tarsal bristles are 

 shorter and more numerous. The posterior legs and the abdomen are covered 

 with much shorter hairs ; the abdomen not shining, dusted. The hypopygium is 

 terminal and more enlarged. The wings are somewhat infuscated, broader and 

 with peculiar venation ; costa bent at tip of first vein, so that the anterior edge 

 of the wing is bowed outwardly, beset with spiny hooks from the junction of the 

 auxiliary vein, these hooks gradually becoming straight at about the middle of 



