392 PROCEEDINGS OF THE NATIONAL MUSEUM vol. no 



Stuart Walley of the Canadian Department of Agriculture, Ottawa, 

 for supplying material and to Mr. J. F. Perkins of the British Museum 

 (Natural History) for permission to study material and for his advice 

 on the classification of the Ichneumonidae. I also wish to thank 

 Prof. G. C. Varley of the Hope Department of Entomology, Oxford, 

 for his many helpful suggestions and for lendin'2: me a number of slides 

 from his collection; Mr. E. R. Skinner of the Imperial Forestry Insti- 

 tute, Oxford, who supplied me with larvae of Rhyssa; and Dr. G. Salt, 

 F.R.S., of the Zoological Department, Cambridge University, who 

 supplied me with larvae of Colly ria and Idechthis. 



Since living larvae often give valuable information, I have collected 

 as widely as possible for this study. Most of the slide preparations 

 have been deposited at the U.S. National Museum. Material borrowed 

 from the Canadian Department of Agriculture and the British Museum 

 has been returned. Most of the material sent by Professor Varley 

 has been returned, but material of Orthopelma and Hemiteles that he 

 did not wish returned has been deposited at the U.S. National Mu- 

 seum. Material of Collyria and Idechthis sent by Dr. Salt and material 

 of Rhyssa sent by Mr. Skinner have also been deposited at the U.S. 

 National Museum. Material returned to the Canadian Department 

 of Agriculture (CD A), to the British Museum (BM), and to Professor 

 Varley (GCV) is indicated by initials. Material not so indicated has 

 been deposited in the U.S. National Museum. 



Detailed records (by whom determined, locality, etc.) have not 

 been recorded for any specimens since this information can be ob- 

 tained from the data labels of the collections of bred material (now 

 returned to the U.S. National Museum and the Canadian Depart- 

 ment of Agriculture) from which larval skins were obtained. The 

 procedure adopted in using this bred material was as follows: The 

 collection of preparations of larval skins was numbered and fully 

 labeled; when a larval skin was extracted from the cocoon of a bred 

 specimen a label was added to the pin of the specimen reading "Larval 

 skin removed; slide No. X; J.R.T.S.; 195X." Thus, it is possible to 

 refer from the preparation of a larval skin to the adult and its de- 

 termination. 



Methods 



Much of the material used was available as cast skins in the cocoons 

 of bred ichneumonids. The contents of the cocoon, the final instar 

 larval skin and the meconium, were removed by making a longitudinal 

 cut in the cocoon and then boiled in a 5 percent solution of caustic 

 potash. Sometimes larval skins of instars previous to the final were 

 found in the cocoons. After boiling, the cleaned and softened larval 

 skins were washed in distilled water, stretched, dehydrated, and 



