INTRODUCTION. 



I propose in this volume, not to give a general history of the 

 Wasps of America, but only to lay the foundations of the fauna 

 of the Vespidae of that continent, principally of North America. 

 I leave aside whatever concerns the habits of these insects, on 

 which we have but insufficient information, and I shall confine 

 myself to speaking of them with respect to the genera or species 

 which offer salient peculiarities. 



This work is not to be taken for a mere catalogue of species, 

 of no further use than to satisfy curiosity. I think that modern 

 zoology ought to tend towards another aim. The existence of 

 species, the composition of fauna, their relations with the parts 

 of the globe which they populate, are not merely accidental facts. 

 In my opinion, we must therein detect the last material and tan- 

 gible manifestation of physiological forces, elucidating the study 

 of which belongs to the domain of the highest natural philosophy. 

 By him who adopts this view of the subject, a far-searching study 

 of species ought to be considered as one of the bases from which 

 the search after the origin of species may start. 



It would seem that in zoology we should take for a starting, 

 point the actually existing forms in which life manifests itself, and 

 to ascend from them up to the primitive stock; just as in geology, 

 we start from the actual existing structure of rocks and from the 

 external configuration of the soil, to follow up the concatenation 

 of the ancient events which have brought about as a last result 

 the present state of the earth's crust. 



The study of species ought especially to serve as a means of 

 revealing to us their variations and the affinities between them. 

 These affinities point to a common relationship, which is to be 

 explained only by a direct affiliation of the types. The study of 



( *i ) 



