426 PROCEEDINGS OF THE NATIONAL MUSEUM vol. no 



the length of the skin setae is equal to three-quarters of the length 

 of the mandible in Polyhlastus, whereas in Erromenus the setae are 

 small and equal to one-fifth of the length of the mandible. 



Larval Key 



1. Mandible without teeth; thi-ee sensilla on each maxillary and labial palp 



Polyblastus 

 Mandible with teeth; two sensilla on each maxillary and labial palp. 



Erromenus 



Tribe Cteniscini 



Figure 13d 



Members of this tribe parasitize the larvae of Argidae, Tenth- 

 redinidae and Diprionidae. Exenterus ahrwptorius (Thunberg), E. 

 adspersus Hartig, E. canadensis Provancher (fig. 13d), E. claripennis 

 Thomson, and E. tricolor Roman have been examined. 



All the head sclerites except the prelabial are present; the lateral 

 parts of the labial sclerite meet the ventral almost at right angles; 

 each maxillary and labial palp has two sensiUa, both round, one large 

 and one small; the mandible is without teeth; the antenna is disc-like 

 and has three prominent sensilla; the closing apparatus of the spiracle 

 is long and slender and its distance from the atrium is roughly equal 

 to the length of the closing apparatus; spines are conspicuous on the 

 skin and their length is about half that of the setae. 



The following are figured in the literature: Exenterus ahruptorius 

 (Thunberg) (Alorris, 1937), E. adspersus Hartig (Beirne, 1941), E. 

 tricolor Roman (Morris, Cameron, and Jepson, 1937). 



Subfamily Cryptinae (=Gelinae) 



Figures 13e-27, 64 



Most members of this subfamily are ectoparasites but some are, or 

 can be, endoparasites. Mr. J. F. Perldns (in litt.) has informed me 

 that in Polyiribax (Aptesini) the parasites emerge from the pupa of 

 the host. Rosenberg (1934) states that he reared Cry plus sexannulatus 

 Gravenhorst and Agrothereutes batavus VoUenhoven from cocoons 

 within the host pupae, but that when he reared the larvae of these 

 species they fed externally on host larvae. 



In this very uniform group, the head sclerites are, in general, well 

 developed, although the prelabial sclerite is absent and the epistoma 

 is very lightly sclerotized and is slender and more or less incomplete 

 dorsally, except in Gamhrus where the dorsal part is broad and com- 

 plete; the pleurostoma is usually very lightly sclerotized; the labial 



