ICUXEUMONID.i;. 19 



into which the above sixty have more recently been subdivided 

 upon the discovery of new forms, or points of divergence in thw 

 old ones which had been overlooked or considered insufficient for 

 generic rank. The mere names of the kno\\u genera and species 

 of IciiXEUMOXiD-E occupy over a thousand closely printed pages 

 of Dalla Torre's Catalogue, and many have been added since the 

 publication of that work in ]9U1. 



It will be seen that the following subfamilies, into which the 

 IciiXEUMOxiD-E are now primarily divided, differ only in elabora- 

 tion and detail from the genera above quoted. 



Table of SuhfamiUes of Ichneumoxid.e. 



1 (6) Areolet not peiitagoual, often 



wanting ; abdomen sometimes 



compressed [IcHXErMoxEs dkltoidki, 



2 (o) Abdomen dorsally depressed, basallj Thorns.] 



sessile or rarely subpetiolate. 



3 (4) Metanotiiin rarely longitudinally 



costate ; terebra for exserted .... Pimplin.^, p. 22. 



4 (•']) 3Ietanotum usually longitudinally 



costate ; terebra concealed Tryphonixje, p. 261. 



5 (2) Abdomen laterally compressed, 



basally petiolate OpHiONiN.a:, p. 343. 



6 (1) Areolet pentagonal, never wanting ; 



abdomen always depressed [Ichneusionespentagoni, 



7 (8) Mesopleiu-fe sulcate below ; terebra Thoms.] 



exserted C'RYPTixiE. 



8 (7) Mesopleurfe not sulcate; terebra 



concealed Ichneumonin.b. 



It is probable that nowhere throughout the whole of the 

 Animal Kingdom is generic and specific instability more strik- 

 ingly illustrated than in the Ich:neumonid,i:, which have been so 

 aptly termed the teeth and claws of Nature on account of their 

 devastating properties ; nor is this surprising. How marvellous 

 a thing indeed is it that there should exist constancy of any kind 

 in a group of insects whose larvae are almost shapeless maggots, 

 feeding wholly immersed within the bodies of other insects, oue 

 kind of parasite very often attacking several different species, 

 A\hich in certain cases belong to even distinct orders of insects. 

 As though this were not sufficient cause for instability, we are 

 told by Krieclibaumer (Ent. Xachr. 1889, p. 290) that even when 

 surprised in coitu no criterion is thereby furuished that the 

 sexes are those of the same species, since he maintains that 

 cross-breeding is not uncommon in this family. To take a 

 pair in copula is, however, an extremely rare occurrence, and J 

 have succeeded in doing so only twice in the course of twelve 

 years' experience, though in both cases the sexes were certainly 

 conspecific. Consequently at the very outset caution is necessary, 

 in that each of the subfamilies enumerated above contains so 

 great a variety of forms as to render concise tabulation very 



c2 



