74 BULLETIN 85, UNITED STATES NATIONAL MUSEUM. 



localities: Sacramento, California (A. Koebele), on Convolvulus occi- 

 dentalis, July; Folsom, California (Koebele), on same host, August; 

 Ukiah (?), California (I. J. Condit), on Convolvulus arvensis, Sep tern, 

 ber; Placer County, California (Koebele), on Ceanothus cordulatus, 

 September; Stanford University, California (Crawford), on Salix sp., 

 February (probably only migrants) . 

 Type in author's collection. 



Genus TRIOZA Forster. 



Head not broader than thorax, usually distinctly narrower, 

 deflexed; vertex much broader than long, with more or less of an 

 emargination in front between the two lobes; genal cones variable 

 in length, shape, and trend, usually subacute, always more or less 

 divergent. Clypeus subglobose or pyriform, scarcely visible from 

 in front. Eyes large, hemispherical. Antennae slender, from one 

 to two and a half times as long as width of head. 



Thorax usually arched rather strongly; pronotum short, descending 

 cephalad quite strongly, depressed below level of head and prsescutum; 

 propleurites as in Psylla; epimeron usually shorter than epistemum; 

 pleural suture oblique, not extending to middle of lateral extremity 

 of pronotum, as is the case in Aphalara. Prsescutum usually about 

 as long as broad, narrowed conspicuously cephalad. Legs usually 

 slender; hind tibiae with two or three black spines at apex on inner 

 side and one outside. Wings hyaline, membranous; radius, media, 

 and cubitus diverging at same point from basal vein (R+M + Cu), 

 and cubital petiole (M + Cu) wanting. 



Type of genus. — Trioza urticse Linnaeus. Apparently no species 

 has yet been designated as the type of this genus. Because urticSR 

 is both typical and one of the first known species, it is here designated 

 as the type. 



This is a very large genus and many of its species are difficult to 

 distinguish, as is usually the case in large genera. The same is true 

 of Psylla and Aphalara. Under this generic name there have been 

 described a number of species which differ sufficiently to warrant 

 the erection of other genera for them. The synopsis of species pre- 

 sented in a former paper (Crawford '11a) has been entirely made over 

 and is now much more usable than before. All the species described 

 from America have been included so far as possible, so that it is also 

 much more complete than before. 



Descriptions of the genus, as formerly defined, may be found in 

 Scott 76: 551, and Froggatt '01: 273. Synopses of genera, including 

 Trioza, have appeared in several papers, as in Loew '78: 609; Maskell 

 '89:164; Crawford '11a: 423. Thegenus is redefined here, however, 

 and the descriptions of both genus and species are based on some 

 characters not heretofore used. 



