Exeiasles.] BRITISH ICHNEUMONS. 297 



long, with the anterior slender ; front ones more or less fulvescent or 

 ferrugineous, with the coxae, trochanters and base of femora always black; 

 hind ones not slender, nearly always entirely black though rarely with the 

 tibiae basally ferrugineous ; ,5 ^^ith the third and fourth hind tarsal joints 

 white. Wings slightly clouded ; stigma infuscate-fulvescent, tegulae 

 black, radix and radius infuscate ; areolet sessile. Length, 7 — 11 mm. 



Holmgren says it may be known by the colour of the legs, adding that 

 the wing nervures are similar to those of E./cmorator, from which Thom- 

 son distinguishes it solely by the colour of the hind femora. But I am 

 convinced that E. illusor is nothing but a colour variety of E. nigripes : 

 their structure agrees exactly in ever}' particular, as the following descrip- 

 tion of authors will show. 



\'ar. ILLUSOR : — Head punctate and very little narrowed bL-hind the eyes ; 

 of V immaculate ; of J with palpi, clypeus, labrum, mandibles centrally, 

 the inner orbits and generally most of the face, stramineous ; clypeus 

 deplanate and apically subtruncate. Antennae subsetaceous, elongate 

 and strongly attenuate towards the apices ; of (J as long as the body and 

 immaculate, of 9 two-thirds the length of the body and with joints four- 

 teen to eighteen white above. I'horax gibbulous, stout, punctate and 

 narrower than the head ; metathorax rugulose above with no areas and the 

 spiracles sublinear. Scutellum black. Abdomen elongate-fusiform, 

 glabrous and nitidulous, as long or longer than the head and thorax ; red, 

 with the base of the first segment and more or less of the anus black ; 

 basal segment glabrous and slightly curved, its postpetiole a little dilated 

 apically and hardly twice as broad as the petiole ; fourth segment shorter 

 than the third, plica testaceous ; terebra a little longer than half the first 

 segment, and the anal styles shortly exserted. Legs red, with the coxae 

 and trochanters black ; anterior femora generally basally, the hind ones 

 at their apices, black ; the curved hind tibiae towards their apices more or 

 less broadly, and their tarsi, infuscate with the two or three central joints 

 of the latter white. Wings normal, more or less clouded ; stigma testa- 

 ceous, tegulae piceous; areolet subirregularly subpetiolate. Length, 

 9 — II mm. 



Its variety is of the same conformation, Holmgren tells us, as E. 

 nigripes, especially as regards the analogous wings and legs ; and I have 

 pointed out {I.e.) that the 9 , excepting its red body, very strongly resem- 

 bles that of E. einctipcs, but the head and thorax are more shining and 

 strongly punctate, the former is broader, the antennae are thinner, the 

 wings smaller with darker venation, the metathorax apically more promin- 

 ent at the sides with the metapleural costae more distinct ; I am not, how- 

 ever, aware that these distinctions will prove to be constant ; and shall be 

 by no means surprised if E. cinclipcs, E. illusor and E. nigripes prove but 

 colour varieties of a single species. 



