28 PROCEEDINGS OE THE NATIONAL MUSEUM VOL. 79 



length, each one-sixth longer than thick, club as long as F5, F4, and 

 half of F3 combined; head one-ninth wider than pronotiim and 

 barely broader than mesothorax, side of pronotum papillose wrin- 

 kled, mesopleura aciculate, except lower half of the posterior sclerite. 

 which is feebly or not at all so; parapsidal grooves quite deep; an- 

 terior of propodeal groove limited by a broad V-shaped carina, its 

 apex very obtuse, groove deep and polished on front fourth, the rest 

 subreticulate, other surfaces of propodeum coarsely reticulate, more 

 coarsely so along groove; 11 to 15, more often 12 to 14, setae in row 

 on submarginal vein, hairs at times more closely set ; fourth abdom- 

 inal segment with a few hairs in a transverse row above, ovipositor 

 sheath more hairy, abdomen otherwise bare, all segments perfectly 

 polished and shining. 



Male. — Length 2.2 to 2.5 mm.; the males at hand agree with the 

 females that have the head all yellow except the vertex and occiput. 

 The black on the thoracic nota varies as in the female, but the legs 

 of all the males are distinctly more nearly entirely yellow, only the 

 hind tibiae being darkened outwardly on two specimens and the third 

 has the second tibiae brown also, but feebly; males otherwise like 

 female, except antennae ; scape four times as long as major thickness, 

 reaching almost to middle of F2, pedicel and Fl very nearly same 

 length, Fl one-fifth longer than each of F2 to F4. latter almost equal 

 in diameter, F2 five-eighths as thick as long, F3 and F4 each suc- 

 cessively slightly thicker, club about same in diameter as funiculars, 

 tapering slightly to a blunt tip, and as long as F4, F3. and a fourth 

 of F2 combined. 



Type Z<?caZ%.— Probably Kockford, 111. (Dr. B. D. Walsh). 



Cotyye.—lsl^X^, U.S.N.M. No. 1536 (through A. Bolter, 1890). 



Redescribed from the Manitoba and Fitch specimens referred to 

 below, and checked with the cotype in the United States National 

 Museum. Fragments of a female cotype remain in the latter 

 collection. 



Remarks. — A series of five females and one male belonging to the 

 Canadian national collection were reared by Norman Criddle from 

 galls on a willow on June 10, 1906, at Aweme, Manitoba : two females 

 from Hull in the same collection without host data check well with 

 the description by Doctor Walsh, except that the wing bands of 

 the original material were pale fuscous, whereas the Criddle speci- 

 mens, as well as tAvo males from Fitch's collection, have pale brown 

 bands, which difference might be due to fading through time. The 

 Fitch specimens bear numbers 10185 and 15224, respectively, and 

 one bears information indicating that they came from willow galls. 



It is unlikely that one species of Decatoma inhabits galls on plants 

 of such diverse relationship as willow and oak. Doctor Walsh in 

 describing this species had before him material from a cecidomyidous 



