Kinsey: Studies of Cynipidse 



47 



valves approaching the vertical; second segment covering not more than 

 half the total area ; edges of segments not very oblique, but well rounded 

 ventrally. LEGS: Yellow to brown black, tips of tarsi darker; tarsal 

 claws fine, simple. WINGS : Clear, not ciliate on the anterior margins, 

 cross veins and subcosta rich brown, other veins fine; areolet of moder- 

 ate size; cubitus not reaching the basalis; radial cell open, fairly wide, 

 the second abscissa of the radius somewhat curved ; first abscissa slightly 

 angulate, without a projection; a brown cloud about the base of the 

 radial cell, and between the areolet, the basalis, and the discoideus. 

 LENGTH: 1.7-3.0 mm., averaging nearer 2.0 mm. 



GALL. — None, or only a very slight swelling of the stem. The 

 larval cells are elongate, averaging 2.5 mm. long by hardly 1.0 mm. 

 wide, embedded in the wood, with the lining hardly distinct, and not at 

 all separable. Mostly on young twigs of white oaks. 



RANGE.— California. 



The adults of the two varieties differ mainly in color, but 

 the differences are so marked and constant in series of the two 

 that there can be no question of their distinct nature. 



These differences are correlated with the distribution of 

 each variety in two faunal areas and on two different hosts. 

 Both occur at much the same latitude ; the two type localities 

 are only about twelve miles apart, but at elevations differing 

 by about thirty-five hundred feet. Quercus chrysolepis, the 

 host of variety briinneus, belongs to a northern Sierran zone, 

 which is limited to higher elevations. Q. lohata, the host of 

 variety atrior, is confined to the Californian zone, which is 

 always at a lower elevation. When I first discovered the dis- 

 tinct varieties, some time ago, I was ready to credit the differ- 

 ences in the two to their different hosts. Since then I have 

 found some evidence that host differences are not always im- 

 portant unless two distinct faunal areas are involved. In this 

 case it appears reasonable to ascribe the differences in the 

 varieties primarily or in part to the same distributional 

 factors which have delimited the parallel distributions of the 

 hosts. Where geologic, geographic, and host isolation mark 

 out the same bounds, very distinct forms may well be 

 developed. 



Compsodryoxenus brunneus variety brunneus (Ashmead) 



Compsodryoxenus brunneus Ashmead, 1896, Proc. U.S. Nat. Mus., XIX, 

 p. 129. Dalla Torre and Kiefi"er, 1902, Gen. Ins. Hymen. Cynip., 

 p. 78; 1910, Das Tierreich, XXIV, p. 704. Beutenmuller, 1909, Bull. 

 Amer. Mus. Nat. Hist., XXVI, p. 281. Fullaway, 1911, Ann. Ent. 

 Soc. Amer., IV, p. 376. Thompson, 1915, Amer. Ins. Galls, pp. 10, 



