DIPTEEA. 305 



Dizonias, spp.l 



Seven females, collected by Schumann in Jalisco at the same localities and at the 



same times with the males of D. phoenicurus and D. lucasi, I refer to three distinct 



species, two of which, without doubt, are the foregoing, and the third, possibly, 



D. tristis, Walk. The very dissimilar coloration of the two sexes of the species of 



this genus, and the uniformity of the structural characters, render it almost, if not 



quite, impossible to collocate them. Observations in the field will be necessary for this 



purpose. As the females of Dizonias appear to be unknown, descriptions of those now 



before me are appended. 



Species A. 

 Black ; bristles of the face black, with white ones intermixed, those of the thorax black ; bristles and hair of 

 the occiput white. Abdomen wholly black, shining ; first segment with a small spot on the sides behind, 

 and the second, third, fourth, and fifth segments each with a spot on the anterior angles (the two spots 

 nearly touching in the middle on the second segment, the following ones becoming more and more widely 

 separated) : they are formed of greyish-yellow dust, and are connected broadly on the venter. Wings 

 brownish-yellow, the distal third or fourth brown. — Jalisco. Two specimens. 



Species B. 

 Antenna wholly red. Face red, blackish above, clothed with orange-red hair. Mesonotum yellowish-red, like 

 the antennas, with a narrow median stripe and a small spot on either side behind, black ; bristles yellow ; 

 pleuras shining black. Scutellum black. Abdomen red ; the first segment, a spot on the second, and the 

 narrow posterior margin of the second, third, and fourth segments, black ; second, third, fourth, and fifth 

 segments each with a yellowish-pollinose spot on either side in front. Legs wholly reddish-yellow. 

 Wings uniformly dark brown. — San Bias. One specimen. 



Whether the remaining examples pertain to one or more distinct species I cannot 

 say with any degree of assurance. They differ from the last as follows : — 



a. Third joint of the antenna black, except the proximal end. Black borders of the abdominal segments 



broader. Pour anterior femora black at the base. — Jalisco. One specimen. 

 6. Antennas black. Black stripes and spots of the mesonotum larger. Abdomen slender, with four golden, 



subinterrupted cross-bands. All the femora black along the upperside. Wings yellow, with the tip 



broadly brown. — Guadalajara. One specimen. 



c. Like b, but with the mesonotal markings similar to those of B. Hind femora wholly black, and the others 



black along the upperside. Wings uniformly brown. (Third antennal joint wanting.) — Santiago 

 Iscuintla. One specimen. 



d. Third antennal joint black. Mesonotal markings almost obsolete. Abdomen very stout and robust, 



yellowish-red, with the first segment and the narrow hind margin of the second and third segments 

 black. Leo-s wholly yellowish-red, the four anterior femora with a little of the blackish colour above. 

 Wings uniformly brownish-yellow. — Jalisco. One specimen. 



These variations seem extraordinary if the insects all belong to one species. I have 

 another female of a Dizonias from Brazil that belongs to the same group, though 

 evidently distinct from any of the foregoing ; it has the hair of the face black, the 

 pollinose markings of the thorax are different, and the whole distal part of the abdomen 

 is black. 



biol. centb.-amer., Dipt., September 1901. 



