18() 



APPEiNDIX. 



MydnH aiidax n. Hp. 



S . — Bl:ick, scc-oiid iilxloiiiinMl scgnicnl, roil on the dorsal as well as 

 Oil the ventral side ; lietul, tliorux unci first jibdoniiiial segment with 

 -Nvliilisli liairs. Loujtli, 23 mm. Wituj, IS mm. 



Very like M. clatdtus in its coloring, but easily distinguialied by its smaller 

 size, comparatively broader head, more cylindrical shape of the alxlomen, by 

 the red color of the second segment, which does not encroach anteriorly, on 

 both sides, upon the first segment (as it does in M. clavatua), which exists on 

 the ventral as well as on the dorsal side of the segment, and which is not 

 interrupted on the dorsal side by a more or less distinct black spot; finally, 

 by the whitish pubescence on the head, the thorax and the first abdominal 

 segment, lleiul black, broader than the thorax, clothed with soft, wliite hairs,- 

 mixed with black ones ; the white hair is especially apparent on the vertex 

 and the sides of the front, also as a small tuft on each side under the antennae, 

 near the orbit of the eye, and as a border round the clypeus. Thorax black, 

 opaque ; the dorsum clothed with white hairs, forming four longitudinal bauds, 

 especially visible from a side view. First segment of the abdomen black, 

 opaque, clothed with long, soft, erect white hair, which reaches down to the 

 hind coxae ; second segment shining, yellowish red, the remainder of the abdo- 

 men black, moderately shining. Venter black, except the second segment, 

 which is yellowish red. Halteres and feet black, pulvilli brownish (of a darker 

 color than in M. ckivatus). Wings strongly tinged with brown, and with a 

 slight puri)lish reflection. Venation like that of M. dnvatus. 



Ik'longs to Oerstaecker's first tribe, that is it has spurs at the tip of the 

 tibiae and the small cross-vein on the posterior border of the wing. 



A single male discovered in the environs of Mammoth Cave in 

 Kentneky, by Mr. F. G. Sanborn, in Jnne, 1874. 



Mj'das carbonifer n. sp. 



$ . — Altogether black, thorax opaqne, abdomen shining, wings 

 brown. Length, 22 mm. Wing, 18 mm. 



Black, front and epistoma shining, beset with black hair ; antennae black, 

 the expanded portion of the third joint brownish, and beset with a fine grayish 

 pollen. I'horax opaque above, showing two velvety black longitudinal lines. 

 Abdomen black, shining, except the first joint, which is opaque. Feet black; 

 ungues reddish, with black tips ; hind tibiae beset with strong spines, except 

 toward their base ; terminal spur strong. Halteres black ; wings dark brown. 



