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UNITED STATES NATIONAL MUSEUM BULLETIN 2 24 



elongate wings, which have a rather characteristic 

 shape and venation. Length 10 to 13 mm. 



Head, lateral aspect : The head is exceptionally short, 

 about twice as high as long. The face is very short 

 and little exposed in profile; it is sometimes slightly 

 rounded and protruding below. Eyes quite short, wide 

 and strongly flattened, anteriorly convex, sometimes 

 more narrow above and with the posterior margin 

 plane at least over its greater middle portion ; the eye 

 is usually not recessive below or more rarely may show 

 a moderate recession. Occiput short in profile or com- 

 pletely obliterated; pile scanty and bristly in some 

 species, in others fine and delicate. The proboscis is 

 laterally compressed, narrowed at the base, wide in the 

 middle and with a moderately high medial ridge ; it is 

 pointed apically, gently convex above and slightly 

 concave on the lower margin, with a number of stiff, 

 bristly hairs apically and below ; there is a pair of long, 

 divergent bristles ventrally in the middle and a few, 

 fine hairs at the base. Palpus clearly of 2 segments, 

 the second cylindrical, attenuate, not porate and with 

 apical bristles. 



Head, anterior aspect: The head is twice as wide as 

 high. Width of face below antenna one-sixth of the 

 head width and slightly divergent below. Subepis- 

 tomal area small, concave and nearly horizontal. Face 

 typically bare and polished on the lower half, densely 

 pubescent above, or wholly pubescent in some species. 

 The face has short, scanty, scattered pile, and on the 

 epistomal margin 2 pairs of long, stout bristles, or there 

 may be some scattered bristly hairs or slender bristles 

 over the middle face and 2 or 3 rows of long, stout 

 bristles below. There is characteristically a transverse 

 frontofacial groove or depression from which the 

 antenna arise. The antenna is attached just above the 

 middle of the head in profile, the first 2 segments short 

 and beadlike, the third smaller than the second, bead- 

 like, and with a very long, thick terminal style approxi- 

 mately as long as the proboscis. First segment with 

 a quite long, stout, ventral bristle; some shorter addi- 

 tional bristles ventrally and dorsally on both segments. 

 Front extremely short, vertical, the vertex moderately 

 excavated and slightly divergent, the rather low ocel- 

 larium placed anteriorly rather than dorsally and car- 

 rying 2 or 3 short, weak bristles behind the ocelli. Eye 

 facets exceptionally enlarged anteriorly but not zoned. 



Thorax: The thorax is pollinose or sometimes 

 coarsely appressed pubescent. Mesonotum exception- 

 ally high and arched. Pile of mesonotum short, rather 

 scanty, ranging from fine to setate and bristly and 

 usually somewhat appressed; the pile is long in some 

 species. There is a well developed acrostical row of 

 bristly hair separated by a wide, bare space. Dorso- 

 central bristles may or may not be differentiated anteri- 

 orly but posteriorly form 1 or 2 rows of moderately 

 long, slender hairs, or sometimes bristles. Lateral 

 bristles absent except on the scutellum where there are 

 3 or 4 pairs or sometimes 5 or 6 pairs varying from 

 stiff hairs to long, slender bristles. Scutellum unusu- 

 ally thick and convex, pubescent, often apilose. 



Propleuron with abundant, long pile; pronotal collar 

 with long, stiff hairs or rarely very slender bristles. 

 Posterior mesopleuron, dorsal and anterior sternopleu- 

 ron, the pteropleuron, and the metapleuron with num- 

 erous, long hairs which on the metapleuron may become 

 slender bristles. Metanotal slopes micropubescent 

 only, lateral metasternum pilose, the ventral metaster- 

 num with short pile. The postmetacoxal area is chitin- 

 ized and moderately wide in many species; in several 

 species it is membranous only. Tegula with bristles. 

 Prostemum not dissociated. 



Legs: All the femora moderately stout; the hind 

 femur is distinctly though moderately thickened either 

 in the middle or throughout the entire outer two-thirds 

 and frequently bearing on both ventral margins stout, 

 tuberculate bristles which may be sometimes reduced 

 in number or size. The hind tibia is sometimes stout 

 from the base or moderately slender at the base and 

 swollen towards the apex. Dorsal pile of the hind 

 femur appressed and setate, all pile slender and bristly 

 and elsewhere mostly erect. A prominent character- 

 istic is the elongate, hind trochanters which are greatly 

 swollen distally, much longer than the coxa and pro- 

 tuberant ventrally ; this protuberance bears a cluster of 

 long, stout bristles. With latitude the species of 

 Damalis will show the following complement of bris- 

 tles; on the hind femur a ventrolateral row, extending 

 from the base to the apex, of 9 stout bristles which may 

 be reduced to as few as 3 smaller, slender bristles with 

 smaller tubercles; medial surface ventrally with similar 

 but fewer bristles; hind tibia with slender bristles, or 

 bristly hairs, 6 or 7 dorsolateral, 5 or 6 dorsomedial, 3 or 

 4 long medial, 4 or 5 lateral, and an equal number of 

 ventrolateral bristles. The middle tibia has long, 

 slender bristles, 3 or 4 situated on the anterior, antero- 

 dorsal, posterodorsal, posterior, and posteroventral 

 rows. Anterior femur and tibia similar, the tibial apex 

 without a spine. The middle tibia sometimes has an 

 apical, bristle-bearing lobe. All tarsi end in stout, 

 sharp claws, long pulvilli and basally swollen 

 empodium. 



Wings: The wings are elongate and slender, always 

 longer than the abdomen. The basal veins of the 

 fourth posterior cell are fused, the anal cell always 

 closed with a long petiole, the marginal cell and all the 

 posterior cells widely open. The alula of moderate 

 length, the ambient vein ends at the anal cell. The 

 species often have the fourth vein sinuous or sigmoid, 

 especially in the more typical members of the group. 



Abdomen : The abdomen is broad, flattened or gently 

 convex, varying from as wide as the mesonotum to as 

 wide as the thorax. There are 7 tergites in the male, 

 the seventh one-third to one-half as long as the sixth; 

 8 tergites present in the female, the eighth one-half as 

 long as the seventh or sometimes fully as long. Pile 

 of the abdomen short, appressed and setate, but con- 

 siderably longer and erect laterally. Sides of the first 

 tergite with 4 or 5 pairs of slender, weak bristles or 

 with only fine pile. Male terminalia moderately large 

 and rotate one-half; the epandrium is sulcate, with 



