92 PE0C;EEDINGS of the national museum. vol. 63. 



Redesci'ibed from the type. The male, peculiar in the extreme 

 elongation of the abdomen, is here described for the first time. It 

 was in the national collection determined by Ashmead. 



57. PLATYGASTER SEMIGLABER (Girault). 



Polymecus semiglaber Girault, Proc. U. S. Nat. Mus., vol. 58, 1920, p. 177. 



The following description may be considered to consist of additions 

 and corrections to Mr. Girault's original description. 



Female. — Length 1.33 mm. Head twice as wide as long, very 

 slightly excavated posteriorly; frons polished, faintly aciculate below; 

 occiput w^ith few transverse raised lines; antennae finely pubescent, 

 the relative proportions of the joints as follow^: Length 48, 13, (i, 8, 

 8, 12, 11, 11, 11, 16; width, 9, 7, 5, 6, 6, 9, 9, 10, 8, 8; length of 

 thorax 15 (0.333 mm.), width 11, height 12;notauli briefly indicated 

 posteriorly, nearly meeting in front of the scuteJlum; scutellum cir- 

 cular, polished, without any trace of a tubercle; length of abdomen 

 0.80 mm. : the following abdominal proportions are taken from a speci- 

 men on a slide; relative length of segments 17, 68, 24, 22, 24,36; width. 

 22, 40, 30, 28, 26, 20; the last tergite is narrowed toward tip, blunt; the 

 ovipositor may or may not be extended; those specimens on the slide 

 have it so because they were subjected to pressure by the cover 

 glass. 



Male. — Length 1 mm. Relative proportion of antennal joints as 

 follows: Length 45, 12, 7, 14, 7, 8, 8, 8, 8, 16; width, 10, 8, 6, 16, 8, 

 S, 8, 8, 8, 7; fourth joint crescent-shaped, deeply excavated on the 

 lower side at base, its attachment to fifth joint on the back of the 

 crescent; antennae sparsely covered with short hairs; joints 5-10 with 

 a short pedicel between each: abdomen about as long as the head and 

 thorax united, broadly elliptical, twice as long as wide, as wide as 

 the thorax. 



Type locality. — Albany, New York. 



Type.— Chi. No. 20610, U.S.N.M. 



The types were reared from the galls of RJiopalomyia Mrlipes by 

 Dr. E. P. Felt. The type series consists of four females and one 

 male mounted on a card point and a male head and four females 

 mounted on a slide. 



The measurements noted in the description were made by means 

 of a disk micrometer graduated to tenths of a iiiillimeter. In meas- 

 uring the antennae and abdomen I used a Bausch and Lomb micro- 

 scope, 160 mm. draw tube. No. 5 ocular and 4 mm. objective. All 

 other measurements in this paper, more particularly those of the 

 thorax, were made with the use of a Bausch and Lomb binocular 

 microscope, No. 5 ocular and 24 mm. objective. With the latter 

 combination 45 divisions in the visual field equal one millimeter. 



