GEXERAX PRINCIPLES OF CLASSIFICATIOX. 



391 



4. Classes. — By a class we understand a group of orders which 

 possess some important structural characters in common. Thus 

 •we hare the classes Monocotyledones, Dicotyledones, and 

 Acotyledones, which present certain distinctive characters in 

 their embryos, from which they derive their names ; and such 

 classes present, moreover, other important anatomical differ- 

 ences. 



The Classes are again subdivided into sub-classes and other 

 divisions, in the same mauner as the orders are thus subdivided ; 

 but as such divisions vary in different systems, and are all more 

 or less artificial, it is not necessary to dwell upon them further. 

 The more important divisions of plants, and those which are 

 found in all systems of classification, are Classes, Orders, Genera, 

 and Species. 



The following table will include all the groups we have al- 

 luded to ; the more important and those of universal use being 

 indicated by a larger type. 



1. Classes. 



Sub-classes. 



2. Ohdees or Families. 

 Sub-orders. 

 Tribes. 

 Sub-tribes. 



3. Gen-era. 



Sub-genera. 



4. Species. 



Varieties. 



Kaces or Permanent Varieties. 



Henslow has taken as an illustration of these different divi- 

 sions Anthyllis Vuhieraria, thus : 



1. Class 



Sub-class 



2. Order 



Sub-order 

 Tribe . 

 Sub-tribe 



3. Gexls 



Sub-genus 



4. Species 



Variety 



Kace 



Variation 



Dicotyledones. 

 . CalyciflorcB. 

 LeguminoscB. 

 . Pa2nlionace(B. 

 . Lotece. 



GenistecE. 

 Anthyllis. 



Vulneraria. 

 Vidncraria. 

 . DiUenii. 

 . Florihi'.s coccineis. 

 . Foliis hirsntissim is. 



