(Jn. Aquid'tr Carnivorous Coleoptera or Di/ti-!cida\ 185 



matter uf subordinate importance. And it seems to uie that a muiierioal linear 

 arrangement might here be of assistance. If genera were numbered consecutively, 

 ^nd the number habitually quoted, we should recognize tlie position of the genus 

 much more easily by means of the number than we do by means of a name; for 

 instance if we have the knowledge that there are about 700 genera of Longieorns 

 and have an idea of the method on whicli they are arranged, and if we knew that 

 in a numerical arrangement of the Coleoptera the Longieorns begin at 3,000, and run 

 on to 3,700, it is clear that we shall at once recognize any number between the tuo 

 just named as indicating a genus of Longieorns : and further that we shall be able to 

 recall in a more or less vague manner, what part of the Longicorn family it belongs 

 to ; whether it comes near the beginning or end of the family and consequently 

 «ome ally with which we are specially familiar. There is a further advantage in 

 a numerical expression of classification, inasmuch as it gives us a prospect of being 

 -able in the futui-e to indicate in an exact manner, by means of a numerical formula 

 the true systematic value of any aggregate we are required to deal with, and thus 

 to ascertain for instance the true difference between the faunfe of two countries we 

 might wish to compare in this respect. A numerical system applied in the way I 

 have indicated, can however express only a linear arrangement, and as this can 

 never be more than an approximation to a natural classification, it is clear that a 

 simple numerical system can never do more than express feebly the complex, 

 relations existing between animals ; moreover, it could only be of full service 

 when applied systematically to all the animal kingdom ; and I have accordingly 

 adopted it here as an adjunct of my classification without attaching to it any 

 considerable present importance ; but still it seems possible that it is in the 

 direction of numerical expression of classification that we may hope for real 

 improvement. 



In the second synthesis the genera are treated as units to be arranged into 

 groups ; and in the third synthesis these groups become the units of which tribes 

 -are formed ; and this metliod of prooeiKling from the simpler to the more complex 

 aggregates is carried on till ultimatel}^ such questions would come to be considered 

 -as whether there really exists an isolation or division of organic beings into 

 vegetable and animal kingdoms. In the present memoir this method of classifica- 

 tion is carried only to the extent of a synthesis of the fifth degree. 



I have already mentioned that during the progress of the work I have had my 

 -attention frequently directed to those problems as to evolution and descent in 

 which naturalists at present are so greatly interested, and the points I have more 

 particularly kept in view were these two. First, are the structures of iiiese 

 creatures of such a kind as to make one believe they may have arisen by gradual 

 modification of a precedent different structure ? and second, are the various re 

 semblances, or affinities as they are called, among the different species such as to 

 make it appear probable they are the results of genetic community of descent 



