234 



PART IV. CLASSIFICATION. 



the natural system cannot be regarded as being perfectly evolved ; 

 the various general sketches which have hitherto been given are 

 therefore no more than approximations to the truth. 



The following are the main divisions of the Vegetable King- 

 dom : 



IST GROUP. Thallophyta. 



Class 1. Algse. 



Class 2. Fungi. 

 2xD GROUP. Bryophyta. 



Class 3. Hepatic*. Sub-kingdom 



Class 4. Musci. ( Cryptogamia. 



3RD GROUP. Pteridophyta. 



Class 5. Filicinae. 



Class 6. Equisetinaa. 



Class 7. Lycopodinee. 

 4TH GROUP. Gymnospermae. 



Class 8. Gymnospermae. Sub-kingdom 



STH GROUP. Angiospermae. Phanerogamia. 



Class 9. Monocotyledones. (Spermaphyta). 



Class 10. Dicotyledones. 



In considering the distinguishing characteristics of these great 

 groups, it may be pointed out, in the first place, that whereas in 

 the Bryophyta, Pteridophyta, and Phanerogamia, without excep- 

 tion, the life-history presents a regular alternation of generations, 

 in the Thallophyta the alternation is generally irregular and is, 

 in many cases, altogether wanting. The Bryophyta differ from 

 the Pteridophyta and the Phanerogamia, in that (a) in their life- 

 history, " the plant " that is, the form to which the name is 

 attached (see p. 2) is the gametophyte, whereas in the two latter 

 groups it is the sporophyte ; and in (fe) the relatively rudimentary 

 differentiation, both morphological and histological, of the sporo- 

 phyte, whereas their gametophyte is more highly differentiated 

 than that of the two latter groups. Finally, though resembling 

 them in many respects, the Gymnospermae and the Angiospermse 

 differ from the Pteridophyta in that they produce seeds : in fact, 

 the Phanerogamia may be contrasted, as seed-bearing plants 

 (Spermaphyta), with the three groups (Thallophyta, Bryophyta, 

 Pteridophyta) of plants which do not bear seeds, and which are 

 collectively termed Cryptogamia. 



