484 



tJNITED STATES NATIONAL MUSEUM BULLETUST 224 



villi, long, bladelike empodium, sharp claws, flattened 

 dorsally, strongly bent apically. 



Wings : The wings are hyaline ; the marginal cell is 

 closed; both branches of the third vein end above the 

 wing apex ; the anterior branch emerges near the end of 

 the discal cell; second basal cell ends with two veins, 

 anal cell closed, fourth posterior cell closed and petio- 

 late; alula large, ambient vein complete. In both sexes 

 there is a short but distinct spur near the origin of the 

 anterior branch of third vein. 



Abdomen : The abdomen is rather robust and some- 

 what shortened and at least as wide as the mesonotimi, 

 also as long as the wings. The first tergite is strongly 

 swollen, convex and ridged laterally. Pile of abdomen 

 scanty, fine and appressed but longer on the sides of 

 the first three tergites in both sexes. Bristles restricted 

 to first tergite, which laterally bears a tuft of 10 to 12 

 weak bristles. Sternites with long, fine pile, except on 

 the first. Male with eight tergites but the last three 

 quite short. In the male the seventh and eighth each 

 dorsally about half as long as the sixth, the sixth half 

 as long as the fifth, the fifth two-thirds as long as the 

 fourth. The sixth and seventh tergites are a little 

 longer laterally. Female with seven tergites well de- 

 veloped, the eighth elongate but incorporated in ovi- 

 positor. Male teniiinalia quite large and conspicuous, 

 elongate, not rotate. The superior forceps deeply emar- 

 ginate or widely cleft laterally ; interior structures ex- 

 posed ventrally. (jonopod large but only about a third 

 as long as superior forceps. Hyandrium well developed. 

 Female terminalia modei-ately but not conspicuously 

 compressed laterally. The upper margin is more or less 

 convex, wider in lateral view than in dorsal aspect; the 

 terminal piece bears only stiff setae. 



Distribution: Neotropical: Gratolestes spectahilis 

 Philippi (1865). 



Genus Cerozodus Bigot 



Figures 372, 712, 1399, 1408, 2442, 2443 



Cerozodus Bigot, Am. Soc. Ent. France, ser. 3, vol. .5, p. 543, 18.57. 

 Type of genus: Asilus nodicornis Wiedemann, 1828, by 

 monotypy. 



Small or medium size flies resembling Asilus Linne 

 but the metanotal callosity is bare and several abdomi- 

 nal segments bear lateral bristles. They are quickly 

 recognized by the odd antenna. The third segment is 

 flat and wide with obliquely truncate apex and in males 

 bears besides, a minute adjacent microsegment, a wide, 

 basal expansion of the style; females with a less modi- 

 fied style. Kemainder of style slender with thickened 

 tip. Length 14 to 17 mm. 



Head, lateral aspect : The head is of medium length 

 and the face short, barely concave on the upper half 

 and with a low, gently rounded, ventrally retreating ele- 

 vation on the lower half. The occiput is quite short, 

 both above and below but is concave medially. The 

 posterior margin of the eye is postero ventrally recessive 

 on the lower sixth ; the lower occipital pile is fine, long 



and abundant. Long, slender bristles begin below the 

 middle of the head and there are 6 pairs which extend 

 upward and are turned downward. At the upper cor- 

 ner of the occiput there are 3 somewhat more stout, 

 vertically directed bristles. The proboscis is small and 

 cylindrical, from the dorsal aspect widened towards 

 the base. The apex is bluntly rounded, the palpus small, 

 cylindrical with bristly pile and slender apical bristles. 

 The antenna is attached a little above the middle of the 

 head and comparatively short. The first segment is 2 

 or more times as long as the small, beadlike second seg- 

 ment. The third segment is wide and flat, abruptly nar- 

 rowed towards the base and slightly narrowed before 

 the apex, leaving the end of this segment obliquely 

 trimcate and slightly concave. It is followed by a 

 small microsegment attached at the dorsoapical border 

 and in females a comparatively short, basally thickish 

 style, also distally thickened, which is as long as the 

 three segments combined. In males, however, the base 

 of this style is expanded into a flat, ventral, wmglike 

 process, the remainder of the style being similar to the 

 female. The apex of the first segment above is extended 

 as a short process. 



Head, anterior aspect : The head is wider below than 

 above and about 1% times wider than Iiigh, the cheeks 

 of moderate extent. The face below antenna is a fifth 

 the head width and divergent below. The upper third 

 of the face is without pile, the surface everywhere 

 pubescent. Above the subepistomal area is 1 row con- 

 taining 3 pairs of stout, long, pale bristles and 2 or 3 

 others dorsally. There are more slender bristles along 

 the sides of the large and oblique subepistoma. On 

 the lower tliird of the face are also 4 or 5 long, slender 

 bristles sometimes black. Front slightly divergent, pol- 

 linose, flat, with a transverse, impressed line, a subocu- 

 lar row of 5 bristles and a sublateral anterior row of 

 4 conspicuous bristles. The vertex is strongly narrowed 

 above, moderately deeply excavated, especially behind, 

 the medium size ocellarium is set far forward so that 

 all ocelli are visible in profile. It bears 2 pairs of stout 

 bristles behind the ocelli. 



Thorax : The thorax is comparatively high and about 

 equally arched anteriorly and posteriorly. The sur- 

 face is pollinose and covered with rather scattered, 

 stubby, fine, suberect setae, including the humerus. 

 Acrostical elements consist of a narrowly delimited, 

 broad, medial band. Posteriorly is a single pair of long, 

 but stout dorsocentral bristles and before and after 

 theni sometimes an additional, slender, bristly hair. 

 The lateral complement of stout, long bristles consists 

 of 2 notopleural, no supraalar, 1 suprapostalar, 1 post- 

 alar, and no scutellar. Scutellum convex with erect, 

 pale setae and faint trace of impressed rim. Pronotum 

 with 3 or 4 pairs of weak bristles. Dorsal and posterior 

 borders of mesopleuron and the anterior basalare with 

 stubby setae. The mesopleuron has some fine pile below 

 and a little on the sternopleuron and pteropleuron and 

 also the posthypopleuron. Metapleuron with a narrow 

 band of slender bristles and bristly pile ; metanotal cal- 



