SYNOPSIS OF NORTH AMERICAN SYRPHID^. 263 



Ceria tridens. 



Ceria tridens Loew, Centur., x, 57. 



Habitat. — Califoruia, Washington Territory! 



<?, 9 . Length, 11 to 12'""'. Closely related to abbreviata; black, sub- 

 opaque; face yellow, with a median black strii)e, sometimes quite broadly 

 oval, at other times narrow, extending- from the base of the antenna! pro- 

 cess to the mouth ; on either side of the base of the antenual process and 

 connected with the facial stripe an oblique stripe runs outward towards 

 the orbit, sometimes reaching it in an attenuated point; cheeks broadly 

 black, sometimes with a slender yellow line; frontal triangle yellow 

 along the border of the eyes, separated in the middle by black ; in the 

 female the yellow may extend across the front, just above the antennal 

 process, elsewhere black, the vertex with a yellow oval spot on each 

 side in both sexes, touching the corner of the eye. Antennae black, 

 joints of nearly equal length; process elongate, about as long as last 

 two joints together; reddish toward the base. Thorax black; humeri, 

 a spot near the outer end of suture, usually a vittula above root of 

 wings, a large oval spot on the meso-pleurse, a smaller one on the 

 steruo-pleurse, and a still smtiller one on the ptero-pleurae, all nearly con- 

 tiguous, and the scutellura in large part, yellow. Abdomen cylindrical, 

 black, finely scrobiculate, the sides of the first segment and the pos- 

 terior borders of the remainder yellow, the second and third of nearly 

 equal width, broader on the sides, the fourth very broad in the middle, 

 attenuate on the sides, and sometimes with a conspicuous lunate spot 

 on each side of yellowish pollen, hypopygium wholly black. Legs, 

 male: Front and middle femora black, except the base and tip; hind 

 femora black on outer half; all the tibiae with a brownish ring before 

 ti|); intermediate joints of all the tarsi brown, last two of hind tarsi 

 black; legs elsewhere yellow. Female: Yellow, the front femora with 

 a (iorsal black streak, the tarsi more ochraceous. Wings brown in front, 

 hyaline behind. 



Four specimens. The third abdominal segment in this species is 

 scarcely longer than the second. 



Ceria nigripennis, n. sp. 



Habitat. — Mexico ! 



9 . Length, 15 to 16"°». Deep black. Face with two large elongate 

 triangular yellow sjiots with the apex below; on either side of the base 

 of the antennal process near the eye a small yellowish spot. Antennal 

 process a little longer than the first joint of the antennae. Humeri, the 

 scutellum wholly, a large spot on the meso-pleurae, a smaller one behind 

 it and nearly contiguous, and a spot on each side of the metanotum, 

 light yellow. Abdomen only lightly constricted at base of second seg- 

 ment ; a spot on each side of the base of second segment, the posterior 

 margin of the same segment narrowly, and of the third segment still 

 more narrowly yellow. Legs wholly black. Wings deep blackish 



