8 BULLETIN 31, UNITED STATES NATIONAL MUSEUM. 



black pile; the tibiae and tarsi are wholly reddish-yellow; and the hiud 

 tibiae and metatarsi seem to be more dilated. 



Var. cothurnatus Bigot. — Two females and one male from Mount 

 Hood, Oregon, agree very closely with the first two specimens, but the 

 third joint of the antennae is acute, the spines of the scutellum are very 

 small, nearly obsolete ; and the tibiae and tarsi are wholly reddish-yel- 

 low. 



Microdon limbus, n. sp. 



Habitat. — Florida I 



9 . Length, 9™°*. Black, moderately shining. Face and front broad, 

 parallel. Face clothed on the sides with golden pile, in the middle 

 chiefly black. Antennae dark brownish red, first and third joints of 

 nearly equal length, the second more than a fourth of the length of the 

 third. Front with only a little golden pile, mostly black, short. Dor- 

 sum of thorax black, with slight coppery reflections, nearly bare. Scu- 

 tellum large, with two large, somewhat ai)proximated spines. Abdo- 

 men broadly ovate, black, but little shining, the second segment ou the 

 sides behind, and the third with a larger oblique spot ou each side, 

 white pubescent or pilose. Legs dark red, the immediate base of the 

 femora black, very short pilose; tibiae rather stout, and gently convex 

 on the outer side, especially the hind pair ; hind metatarsi elongate, 

 flattened, not dilated. Wings cinereous-hyaline in the inner part of the 

 cells ; all the veins, except the base of the fourth longitudinal, with a 

 narrow, very distinct, blackish cloud on each side, those of the last vein 

 separated by a subhyaline interval ; outer cross-vein sinuous. 



One specimen, Florida (National Museum, Professor Riley's collection). 



Microdon, n. sp. 

 Habitat. — Me^xico ! 



9 . Length, 10'"™. A single imperfect si)ecimen from the Isthmus of 

 Tehuan tepee, in the National Museum, shows such remarkable develop- 

 ment of the hind tibiae that I mention it here without giving it a name. 

 It is yellowish red throughout, the dorsum of the thorax and the meta- 

 notum black. The hind tibiae are extraordinarily dilated, cresceutric 

 in shai)e, considerably thickened, and with a dense fringe of black pile; 

 the hind metatarsi are also dilated. The vertex projects strongly. 



Microdon pachystylum, u. sp. 



Habitat. — Georgia ! 



i . Length, 6™™. First antennal joint not more than one-half the 

 length of the third, reddish yellow ; third joint much elongate, cylin- 

 drical, obtuse, more slender in its middle portion, dark brown ; arista 

 basal, much thickened and very short. Front and face broad, of equal 

 width, the margins parallel, clothed with short, light-yellow pile ; face in 

 profile most projecting below, brownish red, shining. Dorsum of thorax 

 black, shiniug, broadly reddish on the sides ; pile short, whitish. Scu- 



