394 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 57. 



THEEONHNI, new tribe. 



Heretofore the genera of this tribe have been placed in the 

 Ichneumonini. As here defined but two genera, Theronia Holmgren 

 and Neotheronia Krieger, occur in the Holarctic fauna. In the 

 tropical regions certain other allied genera occm*. 



In the form of the ovipositor and the secondarily parasitic habit 

 the Theroniini are very distinct, though probably more closely allied 

 to the following tribe, Ephialtini, than to any of the other tribes. 



EPHIALTINI, new tribe. 



The type genus of this tribe is Ephialtes Schrank {=-Pimpla 

 Authors and Pimplidea Viereck)^ while the other genera are Itopledis 

 Foerster and ApechtMs Foerster, in addition to several tropical and 

 oriental genera, such as Xantliopimpla Saussure, EcMhromorpha 

 Holmgren, and AllotJieronia Ashmead. 



Except in superficial facies the Ephialtini are very distantly related 



to the Ichneumonini, to which the genera have almost universally 



been referred. 



POLYSPINCTINI, new tribe. 



This tribe is erected for the genera Polyspincta Gravenhorst, 

 Acrodaciyla Haliday, Colpomeria Holmgren, Zatypota Foerster, and 

 Hymenoepimecis Viereck, all heretofore assigned to the Ichneumonini. 



Their very peculiar habits ally them much more closely than to 

 any of the other tribes of the Ichneumoninae to certain of the Try- 

 phoninae, such as Monohlastus Holm^gren and Polyhlastus Hartig. 

 We believe that the facies and biological aihnities exhibited by these 

 two groups is of much greater importance as indication of relation- 

 ship than are the superficial characters of form of abdomen and 

 length of ovipositor. 



The following six tribes we believe form the true Ichneumoninae. 

 All are externally parasitic and each is related by more or less inter- 

 mediate genera or by common characters of structure and hatitus to 

 one or more of the others. 



Tribe LABENINI. 



Ashmead was the first to recognize this group as a tribe, but in 

 his classification he included also the Ophionine genus Nonnus 

 Cresson. As defined here the tribe includes, of described genera, 

 only Labena Cresson and Grotea Cresson. 



EKYSSINI, new tribe. 



The only author to teat this group as of tribal rank is Morley, 

 other authors having placed the genera comprising it in the Ichneu- 



1 See Cushman and Rohwer, Proc. Ent. Soc. Wash., vol. 20, (1918) 1919, p. 186. 



