INTRODUCTION. Xlll 



modifications more profound because they are more ancient, than 

 as to others of a degree still more advanced. 1 



As may be anticipated from what precedes, my principal pur- 

 pose in producing this work is to study the American fauna with 

 a view to its origin. But this is a work of time which can- 

 not be completed off-hand. The first thing to be done is to 

 study the species carefully, to arrange them according to a good 

 classification, and to describe their affinities. That is the funda- 

 mental preparatory labor. I do not pretend to overstep those 

 limits in this monograph. The knowledge of the American 

 fauna is not yet enough advanced to allow us to draw an infer- 

 ence with certainty as to the affinities of the species among 

 themselves so as to prejudge their filiation. However, I have 

 made more than one remark on this topic, and I will hazard a few 

 words on the matter when speaking of genera and species. But 

 1 reserve for another work the statement of comparisons which 

 seem to me to cast some light on the dispersion of the Yespidae 

 on the surface of the globe and on the modifications which have 

 been worked off under diverse latitudes ; in other terms, on the 

 origin of actual existing fauna. 



The complex affinities of species, and still more the filiations 

 which arise from these affinities, become obvious to the eye only 

 when one has acquired a perfect knowledge of the species and 

 genera of a fauna. To seize them in all their extent, it is neces- 

 sary to know, as it were, all the species of the group by heart 

 in order to be able to take it in at a glance, or to examine at 

 pleasure each part in the picture that one has formed in one's 

 memory. Only when one has attained this point in the study of 

 a group, is it possible, from the inspection of a species, to feel 

 its affinities: for they do not always appear in the more easily 



1 Unfortunately, in our times the greater number of entomologists have 

 deviated too far from this philosophical path. They have turned ento- 

 mology into a sort of amusement which has for object the discovery of 

 Dew species; which loses itself in minutiae, and at the bottom of which 

 there exists no thought. Thanhs to this tendency, collecting has ceased 

 to be the means, and has become the object. In becoming an amusement 

 entomology has gradually lost caste ; it has fallen into the hands of daw- 

 dlers, and thus lost a part of its scientific character. This transformation 

 has led men, who aim at reaohing an elevated rank in science, to be too 

 much inclined to withdraw from the field of entomology. 



