ICHNEUMON. 137 



ICHNEUMON. 



Ichneumon, Linnaeus, Syst. Nat. ed. i. (1735) ; Wesmael, Nouv. Mem. Ac. Brux. 1844, p. 18. 

 Hoplismenus, Wesmael, I. c. p. 13. 



The arrangement of the species of this genus is a work of great difficulty, and indeed 

 cannot be effected in a satisfactory manner until a much larger number of species 

 have been brought together for study. As already remarked, though we find great 

 variation in the structure of the antennae, thorax, and abdomen, yet these peculiarities 

 merge gradually together, and thus the task of splitting up the genus into more or less 

 clearly defined sections cannot be carried out as one would wish. Another difficulty 

 lies in the fact that very many species are only known as males ; and these, as a rule, 

 do not afford such good characters for specific discrimination as do the females. 

 Cresson experienced the same difficulty when dealing with the Mexican species *, and 

 my task of systematically grouping them has been greatly increased by my having seen 

 very few of this author's species. Under these" circumstances I have thought it best to 

 follow Cresson's arrangement, interpolating the numerous new species near those of 

 this author to which, from the descriptions, I-judged them to be most nearly related. 



Ichneumon is a genus of world-wide/distribution, and already contains several hundred 

 species. 



ScuteUum'^at, subconvex, or convex. 

 1. Ichneumon castor. . ■ ^ ^5 \xf^ i 1^9 jj<j wt^^? 



Niger ; tibiis tarsisque fuscis ; alis brunneis, stigmate^fusco. § . 



Long. 22 minim. • . : . 



Eab. Costa Eica, Volcan de Irazuv^ftPft to ",700.0 feet (Bogefs).- 



Body covered with a short close fuscous ..pubescence. Antennae as long as the 

 abdomen and half the thorax, stout, a little flattened towards the apex, which is 

 fuscous black. Head covered with large, but not very deep, punctures ; clypeal fovea? 

 large, deep ; vertex raised in the centre, and separated from the eyes by a wide and 

 deep depression, which is transversely reticulated ; eyes clearly margined ; an indistinct 

 transverse furrow over the clypeal region. Thorax strongly and closely punctured; 

 pleurae longitudinally striated, the striations strongest on the lower halves. Scutellum 

 not very much raised above the mesonotum, the centre flattish, broader at the base than 

 at the apex, longer than broad, strongly punctured, the punctures running into each 

 other and forming irregular reticulations. Postscutellum rugose. Upper median area 

 of metanotum a little longer than broad, a little narrower towards the apex, closely 

 rugose ; all the arese defined, reticulated ; tubercles blunt ; the apex with a semiper- 

 pendicular slope, straight, the middle not much hollowed. Petiole as long as, if not 

 longer than, second segment, smooth, shining, keeled ; the sides with broad perpen- 



* Gf. Proc. Acad. Phil. 1873, p. 105. 

 biol. CENTE.-AMER., Hymenopt., December 1884. tt 



