820 



MAUD D. HAVILAND 



pterous larvae. The narrow oesophagus opens hy a valve into 

 the vast mesenteron filled with food, which is churned to and 

 fro hy muscular contractions. The mesenteron is closed 

 posteriorly and does not communicate with the proctodaeum 

 until immediately liefore metamorphosis. A pair of short 

 Malpighian tuhules enter the hindgut at its anterior end. The 

 salivary glands extend hack wards to the ninth segment, and 

 lie on either side of the gut ventrally as a pair of long straight 

 tuhes. Behind the head their ducts unite to form the common 

 salivary duct, which opens on the floor of the mouth. The 

 ventral nerve-cord appears as a broad unconstricted band 

 extending l)ackwards into the tenth segment. The rest of the 

 internal structure calls for no particular comment. 



Text-fig. 5. Text-fio. 6. 



The full-grown larv^a, x 25. 



Head of the full-grown larva. 



x75. 



In a cocoon opened carefully when the hyperparasite was 

 almost full groM^n, it was possi))le to watch the transformation 

 into the pupa, and by this means it was determined that 

 the mature larvae of the two forms examined were identical 

 in appearance. Attempts to follow the earlier development 

 in the same way always failed, because exposure to the air 

 caused the decaying tissues of the Aphidius to dry up 

 and thus brought about the death of the hyperparasite. The 

 larval development of the Chalcidoidea has been more studied 

 than that of other Hymenoptera parasitica, but so much 

 diversity exists within the family, owing to secondary modifica- 

 tions induced by various hosts and habits, that a comparative 

 account can throw little light on their affinities. The forms 

 here described agree very closely with that of Torymus 

 propinquis, an ectoparasite of certain Cecidomyiidae, 



