APPENDIX. 373 



* * * Frond plain, hyaline, composed of cells radiat- 

 ing from a centre. Fructification unknown. 



5. Lithocystis (a minute parasite). L. allmanni forms 

 minute white dots on Chrysimenia clavelosa, consisting of 

 fanshaped fronds composed of square cells. 



4. DELESSERICE^E. Frond cellular, continuous, areolated. 

 Coccidia external. Tctraspores collected into definite 

 clusters (sori). 



1. Delesseria. Frond leafy, of definite form, with per- 

 current midrib. 



2. Nitophyllum. Frond leafy, of indefinite form. No 

 midrib (sometimes vague nerves). 



3. Plocamium. Frond linear or filiform, compressed. 

 Much branched, distichous, ramuli pectinate, secund. 



5. EHODYMENIACEJE. Frond cellular, continuous ; the 

 superficial cells minute. Coccidia external. Tetraspores 

 scattered through the frond or forming undefined, cloud- 

 like patches. 



* Frond flat, expanded, leaflike, dichotomous or pal- 

 mate. 



1. Stenogramme. Conceptades linear, riblike. 



2. Rhodymenia. Conceptades hemispherical, scattered. 



* * Frond compressed or terete, linear or filiform, much 

 branched. 



3. Sphcerococcus. Frond linear, compressed, two-edged, 

 distichously branched, with obscure midrib. 



4. Gradlaria. Frond filiform, compressed or flat, ir- 

 regularly branched ; the central cells very large. 



5. Hypnea. Frond filiform, irregularly branched, 

 traversed by a fibro-cellular axis. 



6. CRYPTONEMIACEJE. Frond fibro-cellular, composed of 

 articulated fibres connected by gelatin. Favellidia im- 

 mersed in the frond or sub-external. letraspores immersed 

 in the frond. 



