272 PART III. THE CLASSIFICATION OF PLANTS. 



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

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

 sporophyte. In Batrachospermum 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 FLORTDEE, 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. NEMALIONIN^E. 



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

 transia, Helminthocladia, Nemalion, Scinaia, Helminthora. 

 2. Lemaneaceae : Lemanea. 

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



dium, Wrangelia, Naccaria. 

 Series II. GIGARTININ^:. 



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



, drus, Iridasa, Gymnogongrus. 



,, 5. Khodophyllidaceae : principal genera, Catenella, Bhodophyllis. 

 Series III. KHODYMENIN.E. 



Order 6. Spbaerococcaceae : principal genera, Gracilaria, Sphaarococcus, 



Hypnea. 

 ,, 7. Khodymeniaceae : principal genera, Ehodymenia, Lomentaria, 



Plocamium, Chylocladia, Champia. 



,, 8. Delesseriaceae : principal genera, Delesseria, Nitophyllum. 

 ,, 9. Bonnemaisoniaceae : principal genera, Bonnemaisonia, Lepto- 



phyllis. 

 ,, 10. Bhodomelaceas : principal genera, Polysiphonia, Bbodomela, 



Khytiphlcea, Chondriopsis, Dasya, Laurencia, Vidalia. 

 11. Ceramiaceae : principal genera, Ceramium, Spermothamnion, 



Callithamnion, Griffithsia, Ptilota, Monospora. 

 Series IV. CRYPTONEMIN.E. 



Order 12. Gloeosiphoniaceae : Glceosiphonia, etc. 

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



Halymenia. 



14. Dumontiacese : principal genera, Dumontia, Dudresnaya. 

 15. Nemastomaceae : principal genera, Schizymenia, Nemastoma, 



Furcellaria. 



,, 16. Bhizophyllidaceaa : Poly ides, Khizophyllis. 

 17. SquamariaceaB : principal genera, Peyssonnelia, Petrocelis, 



Hildenbrandtia. 

 Order 18. Corallinaceffi : principal genera, Corallina, Melobesia, Lithe- 



pbyllum, Litbothamnion. 

 Series V. PORPHYRINJE. 

 Order 19. Bangiaceae: principal genera, Bangia, Porpbyra, Erytbrotricbia. 



