124 Annals of the Carnegie Museum. 



mens in which the black is not constricted but extends broadly down 

 to the nasus. Almost the whole nasus and labrum blue. Prothorax 

 with a round blue spot on each side of the dorsum of the middle lobe, 

 and each lateral end of the hind lobe is blue. The pale (blue) ante- 

 humeral stripe was described by de Selys as not reaching to the upper 

 margin of the sclerite," but it does reach there in all the present mate- 

 rial ; its upper end is decidedly narrower and has in some specimens 

 almost entirely faded out, and the Selysian type may have been just 

 such an example ; at mid-height the pale antehumeral stripe is from 

 two fifths to one-fourth as wide as the black mid-dorsal. Much varia- 

 tion exists in the black humeral stripe, even in those males from Cha- 

 pada which have not the black of the frons constricted ; the humeral 

 stripe varying from a condition in which it is as wide as the pale ante- 

 humeral at mid-height and is of subuniform width almost to the upper 

 end of the mesepimeron, through conditions in which it is narrower 

 and forked in the upper part of its extent, the humeral branch reach- 

 ing the upper end of its suture, the mesepimeral branch falling far 

 short of the upper margin of its sclerite, to those where the stripe is 

 broken into two separated parts, a shorter on the upper end of the 

 humeral suture, a longer diverging from the lower part of that suture 

 and running upward on the mesepimeron to about two-thirds, or less, 

 of the height of that sclerite, tapering upward to an acute point. The 

 black stripe on the second lateral thoracic suture is often sharply de- 

 fined. Abdominal segments 4-6 may have a fine pale mid-dorsal line ; 

 8-10 have an inferior black stripe on each side as long as the 

 segments. 



$ (not hitherto described}. Differs from the male as follows: In 

 only one specimen does the black of the frons extend broadly down 

 between the antennas to the nasus ; in all others it is more or less con- 

 stricted or, in four out of twenty-five heads from Chapada, the black 

 of the frons is separated from the black line on the fronto-nasal suture 

 by pale ochre, which color generally replaces the blue of the male on 

 head and thorax. In all the present material the black humeral stripe 

 is in the last of the conditions described above for the male, /. e. , 

 broken into a shorter upper humeral portion and a longer lower mese- 

 pimeral portion, the latter reaching upward to from three-fifths to 

 five-sixths of the height of the sclerite, but never attaining the site of 

 the first lateral thoracic suture, nor curving backward at its upper end ; 

 black line on the second lateral thoracic suture of variable length. 



