8 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 61. 



as long as broad, interociilar space 0.55 transfacial, and area higher 

 than broad; malar space one-fourth eye; antennae 14-segmented ; 

 lengths as (pedicel) 12:9:14:11:9:9:8:8:8:7:7:6:6:8; palpi 5 

 and 3 segmented ; the basal maxillary and middle labial segments very 

 short; sides of pronotum and mesopleiirae smooth. Mesoscutum 

 smooth and shining with about 25 scattered hairs on parapsides ; par- 

 apsidal grooves absent or faint in middle and obliterated at each end. 

 Scutellum disk smooth, rounded behind, clothed with sparse hairs; 

 base with narrow transverse groove without pits. Propodeum 

 slightly rugose in place of usual carinae. Wings not reaching ab- 

 domen. Hind tarsus longer than tibia; claws with weak tooth at 

 base. Abdomen longer than head and thorax, in side view longer 

 than high, compressed to less than width of thorax ; the second ter- 

 gite longest, occupying 0.28 of the length of abdomen; the others all 

 visible and gradually decreasing in length; ventral valves oblique, 

 but not protruding; ventral spine in side view six times as long as 

 broad. Ovipositor hooked at end. Using width of head as a base, 

 the length of mesonotum ratio is 0.75 ; antenna, 2.04 ; ovipositor, 5.8 ; 

 wing, 0.5. 



Length of 36 pinned specimens, 1.5-2.3 mm. ; average 1.9 mm. 



This species is closely related to Aci^aspis politus Bassett, which is 

 a Xystoteras. 



Ty^e.— Cat. No. 24732, U.S.N.M. Thirty cotypes. 



Flost. — Q<ue7'cus alba. 



Galls. — Popularly known as " spangle " galls and first described by 

 Fitch in 1859, these common objects have an extended literature 

 under the name of C ecklomy'm foculum, with good figures by Glover, 

 Beutenmueller, Stewart, Thompson, and Felt, but they have not hith- 

 erto been reared. Osten Sacken suspected that they were due to a 

 Cynipid. 



The galls are attached in groups on the underside of mature leaves, 

 and they are found in September and October. They are button- 

 shaped, 3-4.5 mm. in diameter, covered with a whitish bloom, slightly 

 concave above, with a low elevation in center, the edge sharp and be- 

 coming less upturned as the larval cavity develops, attached by a 

 short slender pedicel, between which and the rim on the under side is 

 a prominent heavy rounded ring of tissue. The larval cavity is cen- 

 trally placed, transverse, with no false chamber. 



Hahitat. — The type material was collected at Ironton, Missouri, on 

 October 5, 1917, and living flies were found in the out-of-door breed- 

 ing cage at Evanston, Illinois, on March 24, 1919, indicating that the 

 emergence is very early the second spring. This delayed emergence 

 probably accounts for the failure of other students to rear it. 



