XTV. ALG^. 



967 



Delesseria rusci/olia. Branch bearing a coccidiiun. 



Plocamium vtUgare* 

 Portion of sterile branch. 



Delesseria rusd/olia. 

 Ooccidium cut lengthwise (mag,). 



Delesseria rusd/olia. 

 Tetrnepore (mag,;. 



Plocamium, 



Portion of branch, bearing a 



favella. 



Plocamium. 

 Stichidium contain- 

 ing quaternary 

 spores (mag.). 



Plocamium, 



Favella cut, 



containing globular 



spores (mag,). 



Delesseria rusctfotia. 



Portion of frond bearing 



tetraspores along the 



median nerve (mag.). 



Corallina qpvcinalis. 



Fructiferous branch 



(mag.). 



Corallina cupressina. 

 Section of a branch 



terminated by a 

 ceramidium (mag,). 



several tubes composing a simple filamentous stem (Polysiphoniay &cX or of mem- 

 branous irregular fronds {Porphyrajy or apparently foliaceous (Delesseria) or cartila- 

 ginous (Iridea), with or without nerves, entire, or latticed {Bemitrema, Thuretia), or 

 umbellate {Gonstantinia), or lomentaceous {Gatenella), or Jungermannoid (Leveillea 

 Polyzonia)y sometimes encrusted with lime and fragile (Gorallinay &c.). Eepro- 

 DUCTIVE ORCJANS of two kinds, monoecious or dioecious. Sporangia superficial, or sunk 

 in the frond and contained in conceptacles of various forms. Spores rounded or 

 oblong, solitary or quaternary. Antheridia of various form, or making a part of the 

 tissue of the frond, composed of colourless cells, each containing an antherozoid with 

 no vibrating hairs or power of motion. The antherozoid s fertilize the sporangium 

 by means of a special tube (trichogyne), 



PKINCIPAL aENEBA. 



Thamnidiura. 



Callithamnion. 



Griffithsia. 



Crouania. 



DudresDaya. 



Ptilothamnion. 



Ptilota. 



