XXX.] CLASSIFICATION. 719 



suppose that the same kind of natural classification which 

 is best in biology will apply also in mineralogy, in 

 chemistry, or iu astronomy. The logical principles whicli 

 underlie all classification are of course the same in natural 

 history as in the sciences of lifeless matter, but the special 

 resemblances which arise from the relation of parent and 

 otlspring will not be found to prevail between different 

 kinds of crystals or mineral bodies. 



The genealogical view of the relations of animals and 

 plants leads us to discard all notions of a regular progression 

 of living forms, or any theory as to their symmetrical 

 relations. It was at one time a question whether the 

 ultimate scheme of natural classification would lead to 

 arrangement in a simple line, or a circle, or a combination 

 of circles. Macleay's once celebrated system was a circular 

 one, and each class-circle was composed of five order- 

 circles, each of which was composed again of five tribe- 

 circles, and so on, the subdivision being at each step into 

 five uanor circles. Macleay held that in the animal 

 kingdom there are five sub-kingdoms — the Vertebrata, 

 Annuldsa, liadiata, Acrita, and Mollusca. Each of these 

 was again divided into five — the Vertebrata, consisting of 

 ^klammalia, Ueptilia, Pisces, Amphibia, and Aves.^ It is 

 evident that in such a symmetrical system the animals 

 were made to suit themselves to the classes instead of the 

 classes being suited to the animals. 



We now perceive that the ultimate system will have the 

 form of an immensely extended genealogical tree, which 

 will be capable of representation by lines on a plane 

 surface of sufllcient extent. Strictly speaking, this genea- 

 logical tree ought to represent the descent of each indi- 

 vidual living form now existing or which has existed. It 

 sliould be as personal and minute in its detail of relations, 

 as the Stemma of the Kings of England. We must not 

 assume that any two forms are exactly alike, and in any 

 ca.se they are numerically distinct. Every parent then 

 must be represented at the apex of a series of divergent 

 lines, representing the generation of so many children. Any 

 complete system of classification nnist regard individuals 

 as the infimai species. But as in the lower races of animals 



' Swainson, " Treatise on the Geography and Classification oi 

 Animals," Cabinet Cyclopcedia, p. 201. 



