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UNITED STATES NATIONAL MUSEUM BULLETIN 22 4 



base is a little narrowed, the distal half slightly nar- 

 rowed; the apex bears a stout, cylindrical, apically 

 truncate, spine-tipped microsegment which is twice as 

 long as wide. 



Head, anterior aspect : The head is broad and almost 

 as wide as the thorax ; the face is quite wide, not quite 

 one-third the head width and a little divergent below. 

 It is unusually densely covered with very long, quite 

 slender bristles and bristly pile. Subepistomal area 

 large, concave, oblique. Front very short, with a 

 dense tuft of long bristles beside each eye margin and 

 numerous, shorter bristles submedially. Vertex deeply 

 excavated, the whole sides of the vertex densely beset 

 with long, coarse pile. Ocellarium only moderately 

 large with on each side a tuft of long, bristly hairs, 

 each containing 10 to 15 elements. 



Thorax: The mesonotum is broad, long and low 

 and densely covered with coarse, rather long, nearly 

 erect, straw colored pile which is black anteriorly on 

 the humerus and nowhere differentiated. Lateral 

 bristles are absent; some of the elements on the post- 

 alar callosity, among the dense, long pile present 

 there, perhaps approach the character of bristles. The 

 whole posterior half of the thick, convex scutellum 

 is very densely covered with the same long, bristly, 

 pale pile. All pleural pile black, except on the meta- 

 pleuron where all, except the flattened anterior sur- 

 face of the very convex metapleuron, is densely covered 

 with quite long, yellow, bristly pile. Posterior bor- 

 der of the mesopleuron with a dense fringe; upper 

 pteropleuron with a dense, large cluster of long black 

 pile; there are more scattered hairs present on the 

 posterior hypopleuron, upper sternopleuron, antero- 

 dorsal mesopleuron and whole of the propleuron. 

 Sternopleuron pilose; postmetacoxal area with a com- 

 plete but short triangle of chitin continuous with the 

 narrow extension from the lateral metasternum. Pro- 

 sternum fused and continuous. 



Legs : The femora are exceptionally stout and swol- 

 len, especially the first four, which are not only short 

 but extremely robust. The tibiae are almost as wide 



as the femora. The tarsi likewise are unusually 

 robust, the middle and anterior tarsi remarkably 

 shortened. The pile of the legs is dense, bristly, and 

 rather long and subappressed on the dorsal and pos- 

 terior surfaces of the tibiae; on the dorsal surface of 

 the middle tibia it grades off into a wide band of 

 slender, sharp bristles containing a large number of 

 elements. First four segments of the anterior tarsi 

 of nearly equal length, each greatly swollen. Claws 

 remarkably stout, strongly curved from the base and 

 very bluntly pointed; the pulvilli are rather large, 

 thick, comparatively slender and roimded at the apex ; 

 the empodium is reduced to a triangular, pointed, 

 swollen, basal stub. 



Wings : The wings are broad at the base, gradually 

 becoming narrowed towards the apex. Marginal cell 

 closed with a long stalk; the anterior branch of the 

 third vein curves forward to end well above the apex 

 of the wing and not far from the stalk of the mar- 

 ginal cell. The posterior branch ends far behind the 

 wing apex; the rectangular anterior crossvein enters 

 the discal cell near its base and as a result the posterior 

 cell is extremely long; this cell is also very narrow 

 and narrowly open or closed in the margin. Lower 

 end vein of the discal cell long and drawn towards 

 the base. Fourth posterior cell closed with a short 

 stalk; anal cell closed with a long stalk; the ambient 

 vein ends at the beginning of the anal cell. Alula 

 very large. 



Abdomen: The abdomen is exceptionally broad and 

 robust, wider than the thorax and shorter than the 

 wings. The abdomen is rather flattened over the mid- 

 dle portion and a little more convex laterally ; the pile 

 is everywhere quite dense, coarse and erect, with bris- 

 tles absent. There are eight tergites in the female, 

 the seventh and eighth each from a third to a fourth 

 as long as the sixth. Female terminalia short and 

 broad, with a medial depression, each half densely be- 

 set with bristly pile. No males seen. 



Distribution: Nearctic: Dasylechia atrox Williston 

 (1884). 



Tribe Andrenosomini 



The members of this tribe have a characteristic type 

 of proboscis that is dorsoventrally depressed ; it tends 

 to be greatly swollen and stout basally, with only the 

 portion near the apex thinned and pointed when exam- 

 ined in lateral aspect. In most of these genera the 

 structure is quite wide apically from the dorsal aspect, 

 but it is rather conical and acuminate in Proagonistes 

 Loew. All the members of the tribe agree in one par- 

 ticular; the second palpal segment is excavated and 

 unrolled into a thin, leaflike, sometimes pilose struc- 

 ture, and by this character they are sharply separable 



from the Laphriini in which the second palpal segment 

 is normal or cylindrical in shape. The tribe includes 

 some very large, robust, handsome species as, for exam- 

 ple, the "woolly-pilose" flies of Hyperechia Schiner, 

 which mimic xylocopine bees. The very large, elon- 

 gate, bare, long-legged flies of the genus Proagonistes 

 Loew are likewise remarkable. Members of this tribe 

 occur in all the world regions but are scarce in Aus- 

 tralia and southern South America. They appear to 

 be better developed in the Palaearctic and Ethiopian 

 regions. 



