4 G. E. J. NIXON 



within its wide limits an appropriate place for the new species that passed constantly 

 into his hands. The later monograph comprises as much as he was able to finish of his 

 project to revise the Apanteles of the Palearctic region. 



More recent contributions have been provided by de Saeger (1944) who worked out 

 the Microgasterinae of the Belgian Congo, Granger (1949) who included a revision of 

 the Microgasterinae in his work on the Braconidae of Madagascar and Telenga (1955), 

 who has monographed the group for the U.S.S.R. 



In N. America, Muesebeck has been responsible for nearly all the work that has been 

 done on the Microgasterinae and his two major revisions (1920 and 1922) have not 

 been superseded. 



The above writers have provided the main sources from which I have culled 

 information concerning the traditional classification of the Microgasterinae. As for 

 the actual material on which this revision is based, I have had at my disposal the very 

 large amount of material accumulated by Wilkinson and received by him from almost 

 every part of the world. I have also had the added advantage of being able to study 

 the various rich collections of Microgasterinae that have been acquired by the British 

 Museum from various sources. And last, but by no means least, I have been 

 immensely helped in formulating ideas about the classification of these parasites by 

 the fine collection of Microgasterinae made by C. F. Baker in the Philippines and lent 

 to me by the authorities of the U.S. National Museum who, in forebearing to reclaim 

 a loan of many years' standing, have shown a patience and understanding of which I 

 am deeply appreciative. 



In addition, various entomologists have helped me. I express special thanks to 

 Dr. C. F. W. Muesebeck of the Bureau of Entomology, U.S. National Museum for 

 much kind help and to Mr. R. L. E. Ford for his persistence in trying to secure for me 

 series of rare or little known species from Great Britain, by breeding them from their 

 hosts. 



Others who earn my sincere thanks are : Dr. Max Fischer (Naturhistorisches 

 Museum, Vienna) ; Dr. Ch. Granger ; Dr. Wolter Hellen (Helsinki Museum) ; 

 Dr. E. Papp (Bakonyi Museum, Veszprem) ; Dr. H. K. Townes. 



Finally, a few words are necessary about the treatment of species. For some 

 genera and groups of species within genera, all information about the species is 

 given within an extended key. But in my treatment of the ater-gvoup of Apanteles 

 and a few other groups, most of the information is given in the text, separately from 

 the key. 



All the drawings were done by me ; they are intended to be used comparatively 

 and without their help not much progress is likely to be made through the keys. 



TERMINOLOGY 



In describing the various veins and cells of the wings I have followed Rohwer and 

 Gahan (1916). Their system has been used extensively by workers on parasitic 

 Hymenoptera, although it finds little support in more recent studies on the homolo- 

 gies of the insect wing. Unfortunately, the Rohwer-Gahan system, itself an 

 attempt to stabilise what was most useful in the original Jurinean system, has not 



