FAM. XEXID.E 



25 



flattened. Prothorax and mesothorax transverse, arcuate anteriorly, roundly excavate posteriorly, 

 longest on lateral margins. Elytra about as long as width of thorax, club-shaped. Mesopleura; bearing a 

 very- distinct lobe protecting the entrance of the mesostigma. Metathorax elongate; praescutum rounded 

 in front, broadest at anterior third ; scuti narrowly separated by scutellum ; scutellum elongate triangular, 

 with sides sinuate and apex narrowly truncate; postlumbium transverse, of a different consistency from 

 the other parts: postscutellum elongate, sides converging from middle to rather narrowly rounded apex 

 Wings having eight primary veins from base, the third anal sometimes indistinct, radius sometimes 

 broken for a short distance, one detached vein between radius and medius and often one behind medius. 

 Coxae contiguous. Tarsi four-jointed, without claws. CEdeagus inflated and bent near base, becoming 

 tube-like, and sharply bent again before apex, which is acute, genital pore between last bend and apex, 

 on outer side. 



Female. — Cephalothorax not as a rule abruptly narrowed behind stigmatal angle, elongate 

 trapezoidal, obtuse or truncate at apex. Stigmata seldom laterally prominent. Mouth ventral, with 

 mandibles on each side, rather broad and obtuse. Abdomen with four median genital tubes on second to 

 fifth segments. 



Triungulinid. — Bod}" oblong, slightly narrowing posteriad. First eight segments normal, ninth 

 greatly elongate, deeply emarginate for tenth, which is elongate and terminated by two stylet-bearing 

 lobes, contiguous at base. 



Type of genus. — X. vesparum, Rossi. 



Geographical distribution of species. — Parasites of wasps of the genus Polistcs. 

 i. X. auriferi, Pierce, Proc. U. S. Xat. Mus. Vol. 40, p. 498 (191 1). California. 



-. X. bowditchi, Pierce. Massachusetts, Ohio. 



Acroschismus bowditchi, Pierce. Bull. U. S. Xat. Mus. no. 66. p. i3o, pi. 7, 

 it. 2, 6. 11 ; pi. 9. f. 1 (1909). 



3. X. bruesi, Pierce. 



Acroschismus bruesi. Pierce, Bull, U. S. Xat. Mus. no. 66, pp. 124, 125, pi. 5, 

 ff. 7, 10, 11; pi. 9. f. 2 1909). 



4. X. hubbardi, Pierce. 



Acroschismus hubbardi, Pierce, Proc. Ent. Soc. Wash. Vol. 9, p. 84(1908); 

 Bull. U.S. Nat.Mus.no. 66, pp. 122-124, pi. 6 < ff- I_I2 ; pi- 9> f- 3(1909). 



5. X. hiinteri, Pierce. 



Acroschismus hunteri. Pierce, Bull. U. S. Nat. Mus. no. 66, pp. i3o. i3i, 

 pi. 7. f. 10. pi. 9. f. 4 (1909). 



6. X.jurinei, Saunders, Trans. Ent. Soc. Lond. p. 39 (1S72). 



X. vesparum, Jurine. Mem. Accad. Sc. Torino, Vol. 23, pp. 5o-62. pi. 1 



(1818). 

 X. iirinsi. Pierce, Bull. U.S. Nat. Mus. no. 66, p. 11S, 119, pi. 5. f. 3 (1909). 



7. X. maximus, Pierce. 



Acroschismus maximus. Pierce, Bull. U. S. Nat. Mus. no. 66, p. i32, pi. 9. 

 f. 8 1909). 



8. X. nigrescens, Brues, Zool Jahrb. Vol. iS, no. 2, p. 247 (1903). 



Acroschismus nigrescens. Pierce. Bull. U. S. Nat. Mus. no. 66, pp. 125, 126 

 1909). 



9. X. pallidas, Brues, Zool. Jahrb. Vol. 18, no. 2, p. 246, f. B6 (igo3); Texas. 



Biol. Bull. Vol. 8, no. 5, p. 295, f. 2 (1905). — PI. 4, Figs. I , 

 2, 36, 41 . 



Acroschismus pallidus. Pierce, Bull. U. S. Nat. Mus. no. 66, pp. 126. 127 

 ,1909 . 

 ■oar. lexensis. Pierce, ibidem, pp. 127, 128 (1909). Texas. 



10. X. fieckii, Kirby, Trans. Linn. Soc. Lond. Vol. 11, pp. 116, 117, pis. 8,9 Massachusetts. 

 (i8i3). 



Schistosiphonpeckii, Pierce, Proc. Ent. Soc. Wash. Vol. 9, p. So (1908): 

 Bull. U. S. Nat. Mus. no 66, p. i33, pi. 5, ff. 5, 6 (1909). 



Michigan. 



Florida. 



Texas. 



Switzerland. 



Texas. 



Texas. 



