376 THE MICROSCOPIST. 



7. CERAMIACE^E. Frond filiform, of an articulated fila- 

 ment, simple, or coated with stratum of small cells. Fa- 

 vellce naked, berrjlike masses. Tetraspores external or 

 partially immersed. 



1. Ptilota. Frond compressed, inarticulate, distichous, 

 pectinato-pinnate. Favellce pedunculate, involucrate. 



2. Microdadia. Frond filiform, inarticulate, dichoto- 

 mous. Favellce sessile, involucrate. 



3. Ceramium. Frond filiform, articulate, dichotomous ; 

 the joints opaque. Favellce sessile, mostly involucrate. 

 Tetraspores mostly immersed. 



4. Spyridia. Frond filiform, inarticulate ; the branches 

 clothed with minute, setiform, articulate ramelli. Favellce 

 pedunculate, involucrate. Tetraspores sessile on the ra- 

 melli. 



5. Griffithsia. Frond articulated, dichotomous, or 

 clothed with whorled, dichotomous ramelli, rose-red. 

 Favellce involucrate, sessile, or pedunculate. Tetraspores 

 sessile, or whorled ramelli. 



6. Wrangelia. Frond articulated, pinnate. Favellce, 

 terminal, involucrate with tufts of pear-shaped spores. 

 Tetraspores sessile, scattered on the ramelli. 



7. Seirospora. Frond articulated. Tetraspores arranged 

 in terminal moniliform strings. 



o 



8. Callithamnion. Frond, at least the branches and ra- 

 muli, articulate, mostly pinnated. Favellce terminal or 

 lateral, sessile without involucre (except in C. turneri). 

 Tetraspores sessile or pedicellate, scattered. 



9. Trentepohlia. Frond articulate, branched, cells in 

 single series. Favellce f in terminal corymbs. 



8. PORPHYRACE^E. Frond plain- and very thin, or tubu- 

 lar and filiform, purplish, with oval spores in sori and 

 tetraspores scattered over the frond. 



1. Porphyra. Frond plain, membranous, very thin, 



