BRITISH ICHNEUMONS. 



[Ech/hrus. 



unequal ; head 



teeth equal ; head 



(9)- 



(8). 9. 



Tribe 



XORIDIDES. 



Tabic of Genera. 



Wings with an areolet. 



Areolet distinctl)' pentagonal ; ab- 

 domen petiolate 



Areolet triangular ; abdomen sub- 

 sessile. 



Mandibular teeth 

 cubical 



Mandibular 

 transverse 



Wings with no areolet. 



Abdomen subpetiolate; face anteriorly 

 constricted. 



Abdomen strongly compi'essed, dis- 

 cally cariniform ; metathoracic 

 spiracles circular . . 



Abdomen deplanate, discally broad ; 

 metathoracic spiracles ovate or 

 elongate. 



Hiiid femora dentate beneath 



Hind femora entire beneath. 



Frons distinctly dentate in the centre 



Frons simple 



Abdomen subsessile ; face anteriorly 

 quadrate 



EcHTHRUs, Grav. 



Poe:menia, Holn/gr. 

 Phidias, Vol/. 



Tropistes, G?'av. 

 Odontomerus, Grai 



ISCHNOCEROS, G7^av. 



XORIDES, Lafr. 

 XvLONOMUS, Grav. 



This l>ibe follows the Ciyptinae in natural sequence ; in fact it is 

 difificult to determine where one begins and the other terminates. Thus 

 the more typical genera (the last four enumerated above) are easily known 

 by their cubical head, curiously reticulate exoskeleton and entire lack of 

 areolet. But in Echthrus the areolet is pentagonal and the abdomen 

 petiolate as in Xylophninis {cf. Ichn. Brit. ii. 326); Pocmcnia might perhaps 

 be placed in closer association with Ephialtes ; while Phidias is an alto- 

 gether anomalous genus, related to the Plectiscides, but relegated to the 

 aberrant Pimplinae by its author. Nor are the limits of this Tribe well 

 defined, since some doubt must be entertained respecting Oedematopsis 

 and its allied genera, in spite of their elongate hypopygium ; their economy, 

 however, is undoubtedly related to the Lepidoptera, while that of the 

 present group would appear confined to the lignivorous Coleoptera, and 

 we must regard the records of Ratzeburg, and probably also Giraud, to 

 the contrary with suspicion. Throughout the whole of the parasitic 

 Hymenoptera it will be noted that the head is as a rule cubical in those 

 species (e.g. Hecabolus, Hisieromerus, Cheiropachus, &c.) which prey upon 

 lignivorous hosts. 



ECHTHRUS. GravenJwfst. 

 Gr. I.E. iii. (1829), 861. 



Head subcubical and rectangular ; clypeus short and discreted with 

 an apical lamelliform projection ; eyes oval and prominent. Antennae 

 normal or slender filiform, usually white-banded and always with the 



