44 PEOCEEDINGS OF THE NATIONAL MUSEUM vou 73 



Type— Male, Cat. No. 40483, U.S.N.M. 

 Named in honor of F. X. Williams, the collector. 



BELVOSIA CANALIS, new species 



Male. — Front at vertex 0.30 of the head width, not widening for a 

 little distance. Parafrontals with distinctly yellowish pollen from 

 the anterior part almost to the vertex, where the ground color begins 

 to show dark. Frontals in two somewhat irregular rows. Face, 

 parafacial, cheek, and orbit silvery pollinose. Hairs below the low- 

 est frontals black, cheek with mostly pale hairs. Antennae black, 

 third joint a little more than twice the second. Vibrissae rather 

 high above the mouth, the distance being about equal to the second 

 antennal joint. Facial ridges bristly almost to the arista; palpi 

 yellow; beard white. 



Dorsum of thorax subshining, more pollinose anteriorly; scutellum 

 with brown pollen. 



Abdomen deep black, not very shining on the first two segments; 

 third segment with pale yellow basal pollinose band, covering almost 

 half and interrupted on the middle line. Fourth segment with 

 dense pale yellow pollen, covering all but the apical fifth and even 

 here more or less distinctly visible in diagonal view. First and sec- 

 ond segments of the abdomen with a single pair of median marginals, 

 the hairs of the median region more upright than usual. Third and 

 fourth segments with a marginal row of bristles. Venter with more 

 soft hair than usual, but not so much as in smitM. Outer forceps 

 black, strongly swollen in the basal and middle part, the tip thin. 



Legs black, front pulvilli enlarged, as long as the last two tarsal 

 joints; hind tibia coarsely ciliated, with two larger bristles near 

 middle. 



Wings and calypters brown. 



Female. — Front 0.36 and 0.37 of head width at vertex. Para- 

 frontals not with yellow color, rather plumbeous. Three pairs of 

 proclinate orbital bristles. 



Length, 11-12 mm. 



Described from one male and two females; the male is from Barro 

 Colorado Island, Canal Zone (Greene) ; the females from Campinas, 

 Brazil, March, 1924 (F. X. WilHams). 



Type.— Msde, Cat. No. 40484, U.S.N.M. 



UNRECOGNIZED SPECIES 



BELVOSIA OBESULA Van der Wnlp 



Cnephalia obesula Van deb Wulp, Biologia, Dipt., vol. 2, 1890, p. 46, pi. 3, 

 fig. 3. 



The original description is as follows: 



Blackish; head white; frontal band, palpi, and base of the antennae rufous; 

 scutellum testaceous; front margins of the abdominal segments with yellowish- 



