396 Professor Williston on the 



narrowest a little distance below the eyes ; opaque greyish-yellow, 

 the orbits silvery-grey, becoming broader below ; distinctly keeled 

 on the upper portion, arched below ; on either side, near the silvery 

 orbit with two or three stout bristles ; cheeks and inferior occi- 

 pital orbits silvery-grey. Thorax in ground-colour black, opaque 

 greyish-pollinose, the mesonotum somewhat yellowish or brownish. 

 Abdomen opaque black, the anterior segments lightly greyish- 

 pollinose in well-preserved specimens ; the fifth segment silvery, 

 grey, except the tip ; sometimes the grey is confined to the sides 

 and may also appear on the sides of the preceding segment, 

 especially in the female ; in the male the abdomen is elongate 

 conical ; in the female more oval. Femora for the most part 

 black ; tibise yellow with the middle portion more or less brown ; 

 tarsi yellow, the distal joints brownish or brown. Wings cinereous 

 hyaline ; second section of the costa less than twice the length of 

 the third. Length Ih mm. 



Twenty specimens. St. Vincent. The identity of this 

 species with that which Loew described is somewhat 

 doubtful. The tibias in most of the specimens are 

 yellow, with the hind pair blackish in the middle. In 

 none of the specimens is the last abdominal segment 

 wholly silvery-white. 



2. Discocerina nana, n. sp. 



^. Face considerably narrower than the front, much receding 

 on the lower half, moderately carinate above ; densely silvery- 

 white-poUinose on the sides, leaving a deep black, shining, median 

 stripe ; the two bristles of the sides not strong. Antennce yellow, 

 the third joint rounded, blackish on its margin ; arista with five 

 rays. Front opaque greyish-black, with an elongate median 

 triangle below the ocelli, and the lateral margins on the lower 

 half opaque black. Thorax deep shining steel-blue or green. 

 Abdomen shining black, with slightly coppery reflections. Legs 

 black, the knees, tips of the tibias, and all the tarsi light-yellow. 

 Wings greyish-hyaline ; second section of the costa a half longer 

 than the third. Length 2 mm. 



Numerous specimens. St. Vincent. The cheeks are 

 narrow. 



3. Discocerina facialis, n. sp. (PI. XIII., fig. 141, 



head of 6 .) 



(^ , $ . Front dark-brown, opaque, the sides gently convex, 



except near the vertex. Antennse reddish-yellow, the third joint 



orbicular, brownish on the upper margin. Face broadly arched, 



