144 



UNITED STATES NATIONAL MUSEUM BULLETIN 224 



or 2 additional bristles posterodorsally ; ventrally there 

 are 5 or 6 extremely fine, weak bristles or stiff hairs. 

 This tibia has a double row of dorsal elements contain- 

 ing 5 or 6 bristles each ; a row of 4 or 5 short posterior 

 and a row of 2 long, stout, ventral bristles, but with 

 some additional, long, stiff, oblique hairs. Apical 

 circlet of 9 bristles, without spine. All tarsi end in 

 slender pulvilli, at most two-thirds as long as claw, and 

 long, stout, basally thickened empodium, and sharp 

 claws. In the male the claws appear to be much longer 

 than in the female. 



Wings: The marginal cell is open; the anterior 

 branch of third vein ends well above wing apex; fourth 

 posterior cell closed with a long petiole. Anal cell 

 closed in the margin. Second basal cell closed with 

 3 veins. Alula large; ambient vein complete. 



Abdomen: The abdomen is cylindroid and slightly 

 tapered, considerably longer than the wing. Tergite 

 one is only slightly swollen laterally. Pile of abdomen 

 moderately abundant but flat appressed and especially 

 coarse in the male; the middles of the tergites are 

 largely bare, the sides of the first tergite and base of 

 second with some erect pile. All of the female pile 

 shorter, setate and either erect or suberect. Sides of 

 abdomen considerably rolled, the sternites with short, 

 stiff pile, flat appressed in the male, erect in the female. 

 The first tergite has 5 or 6 pairs of lateral bristles ; none 

 on remaining tergites. Eight tergites present in the 

 male, the eighth tergite one-sixth as long as the seventh, 

 the seventh three-fourths as long as the sixth. Eight 

 tergites in female, the eighth not quite half as long as 

 the seventh. Male terminalia rather large, elongate; 

 the epandrium emitting on each side an extremely long, 

 obtuse, posteriorly directed process. The hypandrium 

 emits a single, medial, long, cylindrical process directed 

 forward, curved and nearly as long as the epandrial 

 lobes. Female acanthophorites with 8 pairs of concave 

 spines: lateral spines apparently absent; ventral plate 

 apically and medially split on the outer third. 



Distribution: Neotropical: Alyssomyia brevicornis 

 Philippi (1865). 



Genus Scylaticus Loew 



Figures 158, 568, 1021, 1030, 1943 



Scylaticus Loew, Ofvers. Svenska Vet-Akad. Forhandl., vol. 14, 



p. 346. 1858. Type of genus: Scylaticus zonatus Loew, 



1858, by monotypy. 

 Euthrix Philippi, Verh. zool.-bot. Ges. Wien, vol. 15, p. 690, 



1865. Type of genus: Dasypogon venustus Philippi, 1865. 



Preoccupied, Lepidoptera, 1830. 



Eather small flies, sometimes quite small, occasionally 

 medium size. They are rather readily recognized by 

 the subglobular head carrying a convex face and ex- 

 ceptionally tumid occiput. The front is divergent and 

 the long antenna has an especially long, laterally com- 

 pressed third antennal segment. The species are almost 

 always bare and short pilose, pollinose flies to which 

 Scylaticus leoninus is a striking exception. Length 8 to 

 17 mm. 



Head, lateral aspect: The face is generally slightly 

 protuberant on the upper half and usually a little more 

 protuberant below and gently convex. The lower facial 

 area is often marked off slightly by a transverse, gentle 

 depression. The eye is long, strongly convex anteriorly 

 and moderately convex behind. The occiput is unusu- 

 ally prominent and tumid throughout its entire length; 

 it gradually slopes down to the eye margin at the ver- 

 tex. The pile of the occiput is long and fine below, be- 

 coming stiff and bristly in the middle with well 

 developed, stout bristles dorsally, which extend from 

 opposite the ocelli over the whole interior dorsal sur- 

 face of the occiput. From the dorsal aspect the eyes 

 are recessive anteriorly leaving in most species a greater 

 portion of the occiput exposed. The proboscis is lat- 

 erally compressed, obtusely rounded, not swollen to- 

 wards the base and tending to be subcylindrical and 

 slightly tapered in many species. The apex has some 

 fine pile directed outward; base with only a few fine 

 hairs below. Palpus clearly of two segments, the first 

 segment short, excavated, the second rather long, 

 slender, cylindrical and somewhat attenuate apically. 

 It has a large apical pore, is obliquely truncate and 

 characterized by reduced pile or bristles distributed 

 over the middle portion laterally and ventrally ; rarely 

 with a bristle at the apex. 



Head, anterior aspect : The face below antenna one- 

 fourth of head width, divergent below to one-third the 

 width. The front is divergent likewise. Subepistomal 

 area small, slightly oblique, concave and bare. The 

 face is pubescent, bearing in the type of genus numer- 

 ous, long, slender bristles. These bristles usually con- 

 fined to the lower half, excepting the narrow lateral 

 margin, but extend all the way up the entire face in 

 abundance in several species : Scylaticus punctatus, ex- 

 quisitus, leoninus and pantherinus. The antenna is 

 attached at the upper fourth of the head ; it is elongate 

 and often quite elongate; the first segment is two or 

 three times as long as the second, the second segment 

 beadlike. The third segment is strongly compressed 

 laterally, rather high or wide in lateral aspect and tends 

 to be curved laterally outward and slightly attenuate 

 from the middle towards either base or apex. This seg- 

 ment carries a distinct microsegment, sometimes two; 

 the apex is obliquely truncate with dorsal, circular 

 opening and exposed, dorsal spine within. Pile of 

 first two segments long and stiff and bristly, especially 

 on the first segment where it is abundant and where the 

 bristles may be quite stout. The front is of moderate 

 length, pollinose, with a tendency to be marked off by 

 longitudinal grooves. Pile of front scanty, with a few 

 fine, long hairs submedially, and characteristically with 

 4 or 5 bristles, usually stout, along the eye margin and 

 sometimes with additional hair on the outer portion. 

 Ocellarium large, the vertex but little excavated; the 

 front and vertex are characteristically divergent, the 

 ocellarium bears 3 or 4 pairs of bristly hairs across the 

 middle, rather short and curled forward and with others 

 behind the ocelli. Anterior eye facets very little 

 enlarged. 



