1 6 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



apply to the male, with the following additions : The third 

 antennal joint is more pubescent than in other species of 

 Pelastoneuriis known to me; the arista is proportionally 

 long, and tapers rapidly. The hypopygium is thick and 

 only half as long as the abdomen; its black lamellae are 

 circular discs fringed with black hairs; its inner append- 

 ages short and thick. 



17. Pelastoneurus dissimilipes, sp. nov. 



Male. Length 4.5 mm.; length of wing 3.5 mm. Palpi and face uniformly 

 covered with gray dust. Antennae rather small, deep black, with the excep- 

 tion of a spinous projection on the inner side of the first joint, which is yel- 

 low; third joint rounded, as broad as long; arista short, tapering rapidly, 

 with short pubescence on its second segment. Front metallic blue. Post- 

 ocular cilia black. Thorax blackish bronze, becoming violet posteriorly and 

 brilliant green near the insertions of the wings. Posthumeral depression 

 broadly white with silvery dust; the deep black band lying mesial to this 

 depression is rather narrow. Abdomen slender, blackish bronze, with green 

 and violet reflections, especially posteriorly, with black incisures, and a large 

 patch of white dust on the side of each segment. Hypopygium black, opaque 

 with gray dust, almost as long as the abdomen but not very thick. Lamellae 

 short, black, triangular, fringed with coarse black hairs; inner appendages 

 piceous. Pleurae uniformly covered with gray dust. Coxae black, dusted 

 with gray, the fore pair with their extreme tips yellow. Fore legs black, 

 only the tips of the femur and the base of the metatarsus yellow; fore tarsi 

 densely padded on their plantar surfaces with short and dense white hairs. 

 Middle legs black with nearly the whole apical half of the femur, and all but 

 the apex of the metatarsus yellow; hind tibia and tarsus deep black, femur 

 yellow with a broad black tip and a broad black band running half way 

 down the middle of its upper surface. Wings grayish hyaline. Fourth vein 

 bending up rather gently towards the third (not forming a distinct angle as 

 in the typical neuration of the genus), so that the space between the third 

 and fourth veins is narrow. Halteres and tegulae light yellow, the latter with 

 black cilia. 



Female. Length 4 mm.; length of wing 4 mm. Palpi large, covered with 

 white dust. Face metallic green, subdued by a layer of gray dust which is 

 thickest on the lower projecting portion. Front metallic green, not very 

 bright. Thorax like that of the male, but with a blackish band down the 

 middle, embracing the acrostichal bristles; anterior portion of thorax dusted 

 with yellow. Abdomen brilliant metallic green, with black incisures and 

 larger patches of white dust on the sides of the segments than are found in 

 the male. Pleurae thickly dusted with white. Coxae concolorous with the 

 pleurae, the fore and middle pairs tipped with yellow. Legs yellow, tarsi 

 blackened from the tip of the first joint; extreme bases of all the tibiae and 

 the basal third of the fore femora black; apical fourth of hind femora dark 

 brown. Venation as in the male. 



