4 bulletin: museum of comparative zoology. 



With the exception of a single genus and species (Ephialtites) 

 from the Upper Jurassic, no parasitic Hymenoptera are known before 

 the Tertiary. However, the quite typical character of Ephialtites, 

 and the abundance in which the group appears in deposits of Lower 

 Oligocene age show that it must have been clearly differentiated and 

 well developed at least before the beginning of the Tertiary. The 

 discovery of Ephialtites in rocks so much older than those in which 

 other of the higher Hymenoptera have been found has led Handlirsch 

 to derive both the parasitic and aculeate Hymenoptera from this type. 

 In this I cannot agree with him and strongly suspect that the greater 

 antiquity of Ephialtites, if it be a truly ichneumonoid form, must be 

 only apparent, and due to our very imperfect knowledge of the earlier 

 fossil insects. However this may be, we know from the Oligocene and 

 Miocene an extremely large fauna which must of course represent only 

 a small fragment of what actually existed. It will be seen from the 

 taxonomic part of this paper that many species are known only from 

 single specimens, which agrees well with what we find in collections 

 of recent species belonging to this group, and evidences not only their 

 verv general occurrence but their high degree of differentiation into 

 numerous closely allied species. 



The beautiful preservation of most of the Florissant species makes 

 it possible to refer the great majority of them to living genera with 

 a considerable degree of certainty — that is of course speaking of 

 recent genera in the wide sense as used by the older writers. In some 

 cases it has been possible to place species with still greater certainty, 

 and in these cases the name of the more modern subdivision or genus 

 in the restricted sense has been employed. Even in the case of speci- 

 mens too poorly preserved to describe, I have rarely been in doubt as 

 to the family to which they should be referred, and well-preserved 

 specimens are usually easily placed in the subfamilies and genera if 

 one is familiar with the details of structure in modern forms, and 

 willing to scrutinize the fossils with great care. This last is extremely 

 important for one is often badly deceived at first sight by obliterated 

 or unduly prominent structures. 



On the whole, the wings are the most important characters to be 

 studied. They are usually well preserved, generally lying between 

 the laminae of the shale where it splits in exposing the specimen. 

 Very few specimens show well-preserved legs, although the hind 

 femora and tibiae often show quite prominently. As a rule the speci- 

 mens can be studied advantageously under a rather strong magnifica- 

 tion, and most of those which I have described were examined under a 



