108 BULLETIN 85, UNITED STATES NATIONAL MUSEUM. 



TETRAGONOCEPHALA FLAVA, new species. 

 Figs. 128, 129, 418. 



Length of body 2.7 mm.; length of forewing 4; width of head 0.92. 

 General color flavous, with seven small black spots on mesonotum; 

 antennae black at tip. 



Head vertical; vertex large, almost square, flat, punctate; genal 

 cones about half as long as vertex, slightly divergent, rounded at 

 apex, a little longer than broad in same plane with vertex. Antennge 

 about one and a third times as long as width of head, slender. Thorax 

 strongly arched, punctate; pronotum moderately long, ascending. 

 Legs long, a little longer than in KatacepTiala. Wings long, about 

 two and a half times as long as broad, hyaline, scarcely rhomboidal, 

 broadly rounded at apex; marginal cells long and narrow; ptero- 

 stigma wanting. 



Genitalia. — Male. — Genital segment partially retracted into pre- 

 ceding segment, very hairy; anal valve very large and broadly ovate, 

 from caudal aspect ; forceps long, gradually enlarging toward apex, 

 with apical fourth converging again to a point; with long hairs on 

 caudal surface. 



Described from one male from Brownsville, Texas (H. S. Barber), 

 May 13, 1904. 



Type.^C&t. No. 18096, U. S. Nat. Mus. 



Genus PACHYPSYLLA Riley. 

 Pachypsylla Riley '83:71. 



Dorsum strongly arched ; body robust. Vertex very large, almost 

 square, flat except apical margin rounded down, nearly or quite 

 perpendicularly mclined. Genal cones small, subcorneal, divergent. 

 Antennae short, seldom longer than width of head. Thorax large 

 and broad; propleurites broad. Legs rather short. Wings more or 

 less rhomboidal, often only slightly so, tliickened, variously colored 

 and maculated; marginal cells long and narrow; pterostigma present; 

 veins usually setigerous. 



Type of genus. — Pacliypsylla venusta Osten Sacken. 



This is a very interesting genus, whose distribution seems to be 

 limited to the United States. The members are gall-makers on 

 several species of hackberry {Celtis spp.), and apparently on no other 

 plants. 



SYNOPSIS OF SPECIES. 



a' . Body very large ; length to tip of folded wings over 5 mm. ; wings maculate apically . 



Gall large, spherical, polythalamous, on twigs or petioles.. WTiusta Osten Sacken. 



a^. Length not over 4 mm. to tip of folded wings. Gall smaller, monothalamous. 



t'. Vertex and thoracic dorsum pubescent; forewings scarcely rhomboidal, about 



two and a half times as long as broad, with a subapical, oblique, whitish band. 



Galls on leaves. 



