318 BULLETIN UNITED STATES GEOLOGICAL SURVEY. 



the pleurae, the dorsum being metallic green, with a coppery stripe in 

 the middle. Abdomen metallic-blue in the male, slightly hoary, espe- 

 cially on the sides, and with black pile ; more greenish and blackish in 

 the female. Hypopygium, as well as its lamellsB, black. Tegulse and 

 their long cilia black. Legs black, only the knees yellowish ; front tarsi 

 somewhat flattened. Halteres dark brown. Wings tinged with gray- 

 ish, more brownish anteriorly. Length about 5"™. 



Hab. — Los Guilucos, Sonoma County, California; not rare on stones in 

 running waters; July 5, 187(5. Four males and two females. 



LlANCALUS. 



In the Monographs, ii, 198, Mr. Loew divides the four known species 

 of this genus into two groups. In the first, the appendages of the hyp- 

 opygium are lamelliform, and the scutellum has only four bristles ; in 

 the second, the appendages are filiform, and the scutellum has six 

 bristles. The Californiau representative of the genus holds the middle 

 between these two groups. It has lamelliform appendages of the hyp- 

 opygium and six bristles on the scutellum. 



LlANCALUS QUEEULUS n. sp. — Male. — Metallic-green; thoracic dor- 

 sum bluish, with four coppery stripes ; posterior orbit with long, soft, 

 white hairs ; antennae black ; cilia of the tegulse pale yellow ; halteres of 

 a saturate yellow, brownish at the root ; scntellum with six bristles. 

 Legs dark metallic-green ; tarsi black ; front coxae elongated, with long, 

 soft, white hairs ; first joint of front tarsi short ; tbe second nearly 

 three times as long, and appearing stouter in consequence of a dense 

 brush of very short, microscopic, erect hairs along its whole inner 

 side ; third joint only a little longer than the first, with a similar brush 

 of hairs ; the two last joints taken together about equal to the third. 

 Wings hyaline, with a large brown spot at the tip, limited anteriorly 

 by the second vein, contiguous to the margin between the tips of the 

 second and third veins, distant from it between the third and fourth 

 veins ; reaching but little beyond the latter ; not sharply limited, rather 

 evanescent on its proximal side. Tbe metallic bluish-green abdomen is 

 whitish-pruinose on the anterior half of each segment, somewhat black- 

 ish along the hind margins. Hypopygium with very small brownish 

 lamellae. 



Female. — The front tarsi have not the same structure as in the male, the 

 first joint being the longest ; wings grayish-hyaline, without any apical 

 spot, but with two small rounded brownish-gray spots, with evanescent 

 outline in the first posterior cell, and a similar spot at the end of the 

 ■discal cell. Length of <? and 9 about 6""". 



Hah. — The Geysers, Sonoma County, May 6. 



SCELLUS. 



1. ScELLUS VIGIL n. sp. — Male. — Thorax grayish above, with two ap- 

 |)roximate brown lines; abdomen and pleurae copper- colored, partly 



