No. 2368. 



AMERICAN SUBTERRANEAN GALLS ON OAK— WELD. 225 



which may even surround small saplings, the number of contained 

 cells somewhat evident externally. (Plate 36, fig. 31.) 



Type locality.— Ravinia, Illinois. Galls collected October 22, 1916, 

 and when cut open about half contained full-grown larvae and half 

 living adults. Host oak not recorded. On May 19 a similar gall 

 was found at Millers, Indiana, in the thick bark of a stump of Q 

 coccinea, and a living fly was cut out, which agrees with the Ravinia 

 specimen in structure, but measures onlv 2.5 mm. Galls found on 

 Q. rubra at Plummer Island, Maryland, and cut open September 21, 

 1919, gave five adults, two pupae, and several full-grown larvae. 



25. CALLIRHYTIS MARGINATA, new species. 



Female.— Head and thorax black, legs and antennae brown, abdo- 

 men almost black. Head evenly rugose, face with whitish hairs 

 clypeus impressed, rough, as long as broad, interocular area 1.1 to 1.2 

 times as broad as high, malar space Arithout groove and 38-0 47 

 eye, antennae 14-segmented, distal half infuscated, first shorter than 

 third, third and fourth subequal, 6-13 gradually shorter, last about 

 twice preceding and incompletely divided above middle by trans- 

 verse groove. Pronotum rugose with parallel ridges on sides ' Meso- 

 scutum finely pebbled, becoming slightly rugose in front, grooves 

 with upturned margins posteriorly, parapsides wider behind, rugose 

 and percurrent, median complete, wider behind, lateral lines smooth 

 anterior not smooth and somewhat indistinct and sunken Scutel- 

 lum coarsely rugose with two narrow, deep, rugose pits at base sepa- 

 rated by a septum, impressed areas at sides. Propodeum with two 

 outwardly-curved ridges inclosing a rugose area wider than high in 

 which in some specimens there is a trace of a median rid^e Meso- 

 pleura finely rugose with no parallel ridges. Legs with coxae intus- 

 cated, hind tarsus shorter than tibia, second shorter than fifth, claws 

 simple, divaricate. Wings hyaline, veins brown, first abscissa of 

 radius angled, cubitus reaching basal, areolet complete, reaching 

 about one-fifth way to basal, surface short pubescent, ciliate onlv on 

 hind margin of hmd wing. Abdomen smooth and polished, longer 

 than high, somewhat compressed, second segment occupving over 

 four-fifths and with inconspicuous patches of hair on sides its hind 

 margin and exposed parts of rest microscopically punctate, ventral 

 spine in balsam about twice as long as broad, ovipositor when dis- 

 sected out about same length as antenna. Using width of head as 

 base, the length of mesonotum ratio is 1.3S; antenna, 2.0; ovipositor 

 2.0; wing, 3.7. ' 



Length of six pinned specimens, 3.6-4.1 mm. Average, 3 9 mm 

 Type.-Czt. No. 22571, U. S. N. M. Two cotypes. 

 Host.—Quercus coccinea Muenchhausen. 

 27177— 21— Proc.N.M.vol.59 15. 



