272 PART III. THti CLASSIFICATION OF PLANTS. 



present an alternation of generations ; the plant is the gameto- 

 phyte (either actual or potential) and the cystocarp is the 

 sporophyte. In Batrachospermuin and Lemanea the life-history 

 is complicated by the polymorphism of the gametophyte. 



The Rhodophycese are almost exclusively marine ; the only 

 fresh-water forms are Batrachospermum, Lemanea, and species of 

 Chantransia, Bangia, and Hildenbrandtia. 



The sub-class, sometimes also termed FLORTDE^;, is subdivided 

 into a number of orders, the limits of which are at present but 

 imperfectly defined, of which the following are the principal : 



Series I. NEM ALIGNING. 



Order 1. Helminthocladiaceae : principal genera, Batrachospermum, Chan- 



tiansia, Helminthocladia, Nemalion, Scinaia, Helminthora. 

 2. Lemaneuceae : Lemanea. 

 3. Gelidiaceas : principal genera, Caulacanthus, Pterocladia, Geli- 



dium, Wrangelia, Naccaria. 

 Sjries II. GIOAETININ^:. 



Order 4. Gigartinaceae: principal genera, Phyllophora, Gigartina, Chon- 



drus, Iridasa, Gymnogongrus. 



,, 5. Bhodophyllidaceae : principal genera, Catenella, Rhodophyllis. 

 Series III. EHODYMENIN^E. 



Order 6. Sphaerococcaceae : principal genera, Gracilaria, Sphasrococcus, 



Hypnea. 

 7. Khodymeniaceae : principal genera, Khodymenia, Lomentaria, 



Plocamium, Chylocladia, Champia. 



8. Delesseriaceae : principal genera, Delesseria, Nitophyllum. 

 9. Bonnemaisoniaceae : principal genera, Bonnemaisonia, Lepto- 



phyllis. 

 ,, 10. Ehodomelaceas : principal genera, Polysiphonia, Ebodomela, 



Ehytiphlcea, Choudriopsis, Dasya, Laurencia, Vidalia. 

 ,, 11. Ceramiaceae : principal genera, Ceramium, Spermothamnion, 



Callithamnion, Griffithsia, Ptilota, Monospora. 

 Series IV. CRIPTOKEMIN^;. 

 Order 12. Glceosiphoniaceas : Gloeosiphonia, etc. 



,, 13. Grateloupiaceas : principal genera, Grateloupia, Cryptonemia, 



Halymenia. 



14. Dumontiaceas : principal genera, Dumontia, Dudresnaya. 

 15. Nemastomaceae : principal genera, Schizymenia, Nemastoma, 



Furcellaria. 



16. Ehizophyllidaceae : Polyides, Ehizophyllis. 

 ,, 17. Squamariaceae : principal genera, Peyssonnelia, Petrocelis, 



Hildenbrandtia. 

 Order 18. Corallinaceae : principal genera, Corallina, Melobesia, Litho- 



pbyllum, Lithothamnion. 

 Series V. PORPHYBINJE. 

 Order 19. Bangiacete: principal genera, Bangia, Porpliyra, Erythrotricliia. 



