ABT. 15. REVISION OF ICHNEUMON-FLIES — MUESEBECK. 6 



Genus ELASMOSOMA Ruthe. 



Elasmosona Ruthe, Berlin. Ent. Zeitschr., vol. 2, 1858, p. 7. — Mabshaix, 

 in Andre, Spec. Hym. Europe, vol. 4, 1888-1890, pp. 389, 549.— Ashmead, 

 Proc, Ent. Soc. Wash., vol. 3, 1895, p. 280 ; Proc. U. S. Nat. Mus., vol. 23, 

 1900, p. 181. — SzEPLiGETi, Gen. Ins., fasc. 22, 1904, p. 104.— Bengtsson, 

 Lund. Uuiv. Arsskr. N. F. Avd. 2, vol. 14, 1918, pp. 1-47. Genotype. — 

 Elasmoso7na herolinense Rutbe (Monobasic). 

 Paramirax Ashmead, Proc. Ent. Soc. Wash,, vol. 3, 1895, p. 281. Geno- 

 type. — (P. scJiicarzi AshmesL6.)=Elasniosoma schioarzi Ashmead (Mono- 

 basic). 

 Head transverse; maxillary palpi 2-segmented, labial 1-segmented ; 

 eyes very large, bare ; antennae very short and straight, shorter than 

 head and thorax united, 13-segmented in female, 14-segmented in 

 male ; mesoscutum without parapsidal furrows ; propodeum abruptly 

 declivous ; radius with three abscissae, the third mostly obsolete ; the 

 radial cell very narrow, open; three cubital cells, the second sub- 

 quadrate ; intercubital veins and cubitus very indistinct ; first discoi- 

 dal cell with very long petiole, and open outwardly, the recurrent vein 

 being absent or very indistinct ; inner spur of posterior tibiae nearly 

 as long as metatarsus; tarsi long and slender, tapering gradually 

 toward apex; tarsal claws exceedingly minute, indistinct; abdomen 

 sessile, flat, and minutely shagreened above, rather sharply margined 

 laterally, and with a pronounced ventral keel ; hypopygium of female 

 broad and peculiarly bifurcate. 



This genus is represented in North America by four species. While 

 no definite host records are available for any of these, all have been 

 taken near ants' nests ; and, in view of the observations on the habits 

 of European species, it seems safe to assume that they are parasitic 

 upon ants. All four species appear to be exceedingly uncommon. I 

 have seen not more than four specimens of any of them. 



KEY TO THE NOETH AMERICAN SPECIES OF ELASMOSOMA. 



1. Abdomen long, slender, about twice as long as head and thorax united, 



strongly compressed, although flat above; legs including all coxae pale 



yellow 1. schwarzi Ashmead. 



Abdomen much shorter, but little, or not at all, longer than head and thorax 

 combined, and not so narrow and strongly compressed 2. 



2. Wings distinctly somewhat fuliginous 2. pergandei Ashmead. 



Wings whitish hyaline 3. 



3. Legs, including all coxae, pale yellow; eyes strongly convergent below, the 



face at base of clypeus much narrower than long down the middle; 

 spiracles of first abdominal segment not prominent— 3. vigllans Cockerell. 

 Middle and posterior coxae blackish ; eyes not so convergent below, the face 

 at base of clypeus at least as broad as long down the middle ; spiracles of 

 first abdominal segment prominent 4. bakeri Ashmead. 



1. ELASMOSOMA SCHWARZI Ashmead. 



Elasmosoma scliimrzi Ashmead, Proc. Ent. Soc. Wash., vol. 3, 1895, p. 283. 

 Type. — In the United States National Museum. 

 This species is at once distinguished from the other known North 

 American forms by the very long and slender abdomen. 



