16 PROCEEDIlsrGS OF THE NATIONAL MUSEUM. vol.63. 



Type locality. — Cadet, Missouri. 



Allotype locality. — Washington, District of Columbia. 



Otlier localities. — Jacksonville, Florida; Mount Graham, Arizona. 



Type.— Cht. No. 2278, U.S.N.M. Female from Cadet, Missouri, 

 selected as type; male of ruhicola from Washington, District of Colum- 

 bia, as allotype; others considered paratypes. 



Redescribed from the type series, five females and one male, in the 

 National Museum at Washington. Two females were reared by C. 

 V. Riley, June 16, 1883, from a Cecidomyid stem-gall on blackberry 

 at Cadet, Missouri. The others were reared June 9, 1886, from Ceci- 

 domyid gall on Vemonia novehoracensis , collected at Washington. 



I have compared the types oi arizonensis (Cat. No. 2279, U.S.N.M.) 

 and brunneipes (Cat. No. 25428, U.S.N.M.) with the specimens 

 refered to above and can find no specific differences. The type 

 series of arizonensis consists of three females and one male, reared by 

 Dr. H. K. Morrison, at Mount Graham, Arizona, from a Cecidomyid 

 gall on wild sunflower. The type of brunneipes was not reared. It 

 was collected at Jacksonville, Florida. 



This species is a most remarkable one. The structure of the 

 abdomen in the female and of the antenna in the male has no par- 

 allel among described Platygasterids. I might create a new genus 

 for it but it is possible to include it in Trichacis and I prefer to let 

 it remain there. 



3. TRICHACIS ARIZONENSIS (Ashmead). 



Isorhombus arizonensis Ashmead, Bull. 45, U. S. Nat. Mus., 1893, p. 277. (Not 

 Trichacis arizonensis Ashmead, 1893, p. 296.) 



Female. — Length 1.80 mm. Head more than than twice as wide 

 as long, wider than the thorax, flattened in front, slightly emarginate 

 behind; occiput and vertex rounded, polished, pubescent except in 

 the middle; entire face polished, without sculpture; pedicel twice as 

 long as wide, as long as joint ten, as wide as five, a little longer than 

 three; joint three twice as long as wide, as long or nearly as the pedi- 

 cel, longer than four; four a little longer than wide, as long but slightly 

 narrower than five, as wide as three; six to nine a little longer than 

 wide, as wide as the scape in the middle; thorax two-thirds as wide 

 as long, strongly convex above, a little higher than wide; pronotum 

 mostly polished, pubescent, partly shagreened laterally; mesopleural 

 furrow deep and wdde; mesonoturo finely shagreened anteriorly, be- 

 hind with long hairs reaching over the scutellar foveae; notauli attain- 

 ing anterior third of mesonotum; median lobe broadly truncate api- 

 cally, not touching the scutellum; scutellum circular seen from above, 

 conically produced and bidentate at the summit when viewed from 

 the side, perpendicular behind, slightly sloping in front, thickly cov- 

 ered with long, evenly distributed white hairs; abdomen broadly 



