22 EEPORT OF THE SECRETARY. 



ness. However, there is nothing absolutely fixed in naturej the forms 

 and the marking, likewise, vary within certain limits. Therefore, the 

 descriptions can only be averages deduced from a certain number of 

 individuals. 



" Theoretically, the description ought to represent, as it were, the alge- 

 braical formula of the species or its ideal type. It is not required that 

 the description sliould tally with the individual, but, on the contrary, 

 that it should represent the average of tlie characteristics of the en- 

 semble of individuals. But in practice the description can never be so 

 perfect, since it is drawn from a certain number of individuals and not 

 from the ensembleof the individuals that represent the species. It is for 

 the reader to know how to seize the connection that exists between the 

 description and the even heterogeneous individuals which lie may have 

 beneath his eye. In a word, my method of description aims above all 

 at generalizing, and requires that the reader should generalize likewise. 

 It cannot suit much the amateur inclined to lose himself in a multi- 

 plicity of details, for whom the collection takes the place of nature, and 

 for whom the determination of an individual is the final purpose of the 

 study of a species. 



"From the principles just laid down it follows that, in the extreme 

 subdivisions of genera, I have usually X)referred the characteristics 

 taken from the form to those taken from the color. Undoubtedly it is 

 less convenientfor the reader, for the natural method is always less easy 

 to follow than the empirical system ; nevertheless I think that it is pref- 

 erable to proceed in that wise, for whatever may be done to seek the 

 natural method a large portion of empiricism is sure to remain, as I shall 

 endeavor to show, in the study concerning the filiation of the species. 

 We cannot, therefore, eliminate too carelully from classification, empiri- 

 cal elements. 



" It is necessary to observe on this head that no absolute rule can be 

 laid down as to the insubordination of characteristics. To be sure, 

 forms varying less than colors, they offer, in general, characteristics 

 more important than the latter ; but there is, however, now and then a 

 case in which the colors are more fixed than certain forms, and assume 

 a real importance; for instance, as being the stamp j)eculiar to a certain 

 geographical zone. Thus, the division Hypodynerus, (genus Odynerus,) 

 which depends greatly on the colors and facies, and which comprises the 

 most divergent forms. In this case the livery becomes the casket of a 

 fauna, and is very important. In the succession of species it is gener- 

 ally observed that the colors vary much even when the forms remain, 

 fixed (or vary less ;) but there are other cases in which it is color that 

 remains stationary while the forms vary." 



In the Smithsonian report for 1858, a paper was published on the 

 method of collecting and preserving insects, prepared by Baron Osten 

 Sacken, of the Bussian legation, wiih contributions by other eminent 

 entomologists, which has rendered valuable service in the way of 



