236 [April 



sima which he proposed as the type of the genus. The cylindrical 

 shape of the joints of the antennas was the only distinctive character on 

 which he established the genus. Zetterstedt (1851) and Walker (1856) 

 gave a more complete definition of the genus, to which Sehiner (1863) 

 assigned its true position, by showing its relationship with Triogma 

 tri&ulcata and Phalacrocera nudieomis. 



Three or four European and one North American species of Cylin- 

 drotoma are at present known. Mr. Loew could distinguish in 1850 

 at least six fossil species included in amber. ( Loew, Bernstein u. Eern- 

 steinfauna, 1850, p. 37.) 



The habits of this genus are very curious ; the larva lives on the 

 under side of the leaves of certain plants, as Anemone, Viola, Stellaria. 

 It is green and has a crest along its back, formed by a row of fleshv 

 processes. It was first discovered and figured by Schellenberg ( Genres 

 des Munches Dipteres in 1803), a circumstance which seems to have 

 been overlooked since. 



The name of the genus is derived from the word cylinder and the 

 verb tsfivu. I cut, in allusion to the cylindrical joints of the antennae. 



1. C. americana n. sp. % . — Flava, capite flavo, thorace nigro-fasciato, anten- 

 narum articulis subcylindricis, elongatis: cellulis posterioribus quinque. 



Yellow, head yellow, thorax striped with black, antennae with subcylindri- 

 cal, elongated joints ; five posterior cells. 



Long. corp. 0.45. 



Head pale yellow, rounded and but little attenuated posteriorly; a pale 

 brown spot on the vertex: palpi brown; the antennae, if extended backwards, 

 would reach the end of the second abdominal segment; two basal joints pale 

 yellow, the first not much longer than the second; third joint yellow at the ex- 

 treme basis only, elongated, cylindrical ; the following joints a little shorter 

 than the third, elongated, subcylindrical, slightly attenuated at the basis: 

 they are nearly of the same length to the end of the antenna; the flagellum 

 is clothed on both sides with a delicate and dense pubescence, among which 

 some longer, but also very delicate verticils are scattered. Thorax pale yellow, 

 opaque above, with a black, opaque stripe in the middle, reaching from the 

 scutellum to the collare and divided longitudinally by a very narrow yellow 

 line; the lateral stripes are dark brown, sometimes pale brown, abbreviated 

 anteriorly and reaching beyond the suture posteriorly; a brown spot on the 

 pleurae, between the root of the wings and the collare and another brown spot 

 on each side of the 2">ectus. between the first and second pair of coxae : halteres 

 pale, dusky at tip: feet yellow, tarsi brown towards the tip. Abdomen brown- 

 ish-yellow, darker along the lateral margins: its tip (in the male) is rather 

 stout, club-shaped. Wings hyaline, very slightly tinged with yellowish-cine- 

 reous; stigma short, pale; the inner and outer section of the second vein are 

 almost of equal length; the first vein ends in the second at about the middle of 

 the outer section of the latter: submarginal cell a little longer than the first 

 posterior: small cross-vein short; discal cell rather large, elongated: its inner 

 end pointed and nearer to the basis of the wing than the inner end of the sub- 



