INTRODUCTORY PAPERS ON ICHNEUMONIDE. 299 
Ichneumon would probably lead to a very material alteration of 
the specific or diagnostic characters. It has been already stated 
that the Ichnewmonide are exclusively parasitic on Lepidoptera, 
and if these had not been so generally despised by lepidopterists, 
as at present, it is probable that we should have a much. better 
knowledge of their systematic arrangement. There are few good 
collections of British Ichnewmonide ; that in the British Museum 
is very rich in specimens, but from its almost chaotic arrange- 
ment this vast materiel is nearly valueless; it contains the 
rich collections of J. F. Stephens (which included those of 
Francillon, Marsham, Haworth, Donovan, &c.) and T. Desvignes ; 
three hundred and twenty-five ichneumons (many still unique) 
from Heysham’s collection were purchased at Stevens’s; besides 
many specimens since added by Walker, Smith, Marshall, and 
others. Ruthe’s general collection of Ichnewmonide is also in 
the Museum, and two hundred and forty-seven Gravenhorstian 
types, sixty-one of which belong to this family. The Hopeian 
Collection at Oxford contains of European ichneumons :—(1) an 
old collection, probably named by Fabricius; (2) several drawers 
filled with Gravenhorst’s types; (3) many species named by 
Stephens; (4) a small collection received from Forster; (5) the 
Saundersian collection, arranged by F. Smith; (6) Westwood’s 
British collection ; (7) a small collection received from Wesmael ; 
(8) the greater part of F. Walker's British collection; (9) several 
drawers of undetermined British specimens, mostly collected by 
Rev. F. W. Hope. The Linnean collection is at Burlington 
House. 
The species of Ichnewmon are all solitary in their parasitism, 
never more than one living in the same host; when more is known 
of their biology it will probably be found that many species are 
conditionally monophagous, that is, they are always attached to 
the same or a closely allied lepidopteron, but to this possible rule 
we already know of several conspicuous exceptions amongst the 
commoner species. It appears that the mother Ichnewmon mostly 
attacks its victim larva when nearly or quite full-fed, but the 
manner or time of oviposition has seldom been observed; as 
many Lepidoptera, especially Noctu@, hybernate as larve, it is 
probable that oviposition takes place in the spring. The species 
of Ichnewmon mostly emerge in the late summer or autumn, and 
very many of these are known to hybernate as imagos, especially 
