298 



THE AMERICAN 



the insertion of tlie front wing. Antenna; (^ 5 usually as in 

 Figure 1, e ^,fc^, 8-jointed or 9-jointed (So +6+C1. or Sc. 

 +7+C1.) , with a club composed of two or three connate and 

 almost confluent joints. Head and thorax very coarsely 

 punctate Abdomen as in Figure 1, c $, rf (^, 8-jointed, 

 polished, and comiiressed, especially 5 j the peduncle or 

 first joint sculptured, ^ about as long as the rest of the ab- 

 domen, § short; (j" with the fourth joint, § with the flfth 

 joint very long and finely and closely ptmctate below. Stig- 

 ma ij" 5 simple. 



' It is not very easy to see the sutures between the joints in 

 the antenna of (f" Euri/toma; but by examining a great num- 

 ber of (fcJ, where the antemuc were imirh c.iiivnlulrd, I 

 ascertained that the crook or elbow w.is al\va> - m ih, /;/. and 

 never at the base of any peduucle. Con -i niiriiil\ , ili< i^'al 

 suture is at the tip of every peduucle, a.s th^wu in llic iiijure. 

 GkndsDecatoma. (Fig. 2, a $, 6 (j".) Cody contractile 

 as in Eurytoma and with a similar groove for the middle 

 femora. Antenuie jj 5 as in Figure 2, e g , f (j' , (5" 7-jointed 

 (So.-l-5-FCl.), filiform, the club slightly compres.sed, $ 

 8-jointed (Sc.+fi+Cl.), gradually clavate, the club consider- 

 ably compressed. Head and thorax vei-y coarsely punctate. 

 Abdomen as in Figure •!, c ^ , d ^ , 8-jointed, polished, and 

 compressed, especially $ ; pedvmcle sculptured, (^ not (piite 

 as long as the rest of the abdomen, $ about half as long; 

 ^ with the fourth joint, 5 with the fifth joint very long. 

 Stigma (j" g thickened, widened and blackened . 



Genus Isosoma. (Fig. 3, 6 5 ; fig. 4, o $ , 6 (f" ) Body 

 not contractile and with no groove to receive the middle 

 femora. Antennas (5' $ as in Figure 4, c 5 , /^J, 9-jointed 

 (Sc.4-7-f-Cl.), ^ filiform and with joints 3-!) subcqual in 

 length, 2 gradually clavate, joints 2 and 4-8 all equally 

 short, 3 longer, 9 alioiit .ik Iraig as 7 and 8 put together. 

 Head and thorax railn r liii.ly iiiun.s,.. Abdomeu as in 

 Figure4, c 5, d (;{>, - . ;,, :i h.,1, cylindrical, (5> Willi 



the ijeduncle short aii.l . .;;,m ' ^ almost sessile; ^-^ witli 

 joints 4 and .') long, i^ rtiili.|.,iui... ., .nid G long. Stigma ,J' g 

 simple. 



fiKNUS EUUYTOMA. 

 Sijnnplical Table tojind the species described bcloic. 

 A. Ailtcnnw female. 8-jointC(I (Sc. -f'^+Cl.) 



a. Head and thorux Jinrtly pale bicolor. ii. ep. 



/>. Hcud and thorax entirely black. 



.... ^ aurieeps, n. sp. 



' / abnorniicornis, n. sp. 



immaculate, generally with the femora and tibi;c, especially 

 2 , more or less lightly tinged or vittate with dusky superi- 

 orly, each succeeding pair of legs more obviously so. lyings 

 hyaline; veins brownish-white, usually towards their tip 

 end ranging into brown-black Length rJO.lI, O 0.08— 

 0.11 inch. 



Described from 1 cf 2 § bred June 3d, n-om a rough, 

 woody.-subglobular, black fungoid swelling upon the twigs 

 of Black Oak, which is infested by an undeacribed Gall-fly, 

 and which also occurs upon Red Oak, but in both oases 

 always very sparingly and sparsely, and never in profusion 

 and locally like the true Cynipidous gall, Q. porf<ijri-«, Walsh. 

 This fungoid growth is the supposed gall referred to by 

 Osten Saoken in Proc. Ent. Soc. Phil. IV, p. 305, note. A 

 very similar but more elongate fungoid growth, which pro- 

 duces no Gall-fly whatever, but from which , as well as ft-om 

 the Oak-fungus, I have bred Trochilium hospes .Walsh, occurs 

 locally, but in the greatest profusion upon the Pig-nut Hick- 

 ory iCarya glabra). From this Hickory- fungus, I have bred 

 the following Beetles: 1st, the rare Chramerus icoriie, Leo. 

 (Scolylidce); 2nd, a iVajda/mtis? resembling at first sight Sf. 

 barbitits. Say, but structurally distinct, and 3d, a Cis which 

 according to LeConte is most probably C pumicatus, Mellie. 

 I have no doubt that the Gall-fly obtained from the Oak- 

 fun.irus is in.|Uilinon.<, as well as the undistinguishable form' 

 bred l..\ Mr. ['.a-.i! 11 111 -;ill- (HI the .stem of some plant 

 su|ip".<'l I" I" .1 ;. :--'■ <i>lrii Sacken, 1. c) Not 



imprnlialili , III ,;i 1 ... 1 mi ih. -,• mustard-galls was 



subsequent page to quote several cases, where gall-flies be- 

 longing to notoriously inquilinous genera are inquilinous in 

 Cecidomyidous galls. Authors have been sometimes a little 

 too apt to jump to the conclusion that, because a particular 

 insect is bred from a psirticular gall, therefore it is the author 

 of that gall . No mode of reasoning can be more unsafe and 

 unsound. 



tFig. 1.1 



$ 0.10— 0.15 inch. 



Described from 12 jj bred Tune 9th— 19th, a single ^ bred 

 August 23d, and 31 $ bred June 9th^July 1st, all from the 

 Cynipidous oak-gall Q. pruniis, Walsh, of the preceding 

 year's growth. I observe in this species ot Eurytoma, an 



