EHODOMELACEiE. 75 



11. Rhodymeniace.e. Frond cellular, continuous, the 



superficial cells minute. Coccidia external. Tetra- 

 spores scattered through the frond, or forming unde- 

 fined, cloud-like patches. 



12. Cryptonemiace.e. Frond fibroso-cellular, composed 

 of articulated fibres, connected together by gelatine. 

 FavelUdia immersed in the frond, or sub-external. 

 Tetraspores immersed in the frond. 



13. CeramiacE/E. _Fro«(/ filifoi'm, consisting of an articu- 

 lated filament, simple, or coated with a stratum of 

 small cells. Favelhe naked, berry-like masses. Te- 

 traspores external, or partially immersed. 



Oeder VII. RHODOMELACE.E. 



Rhodomeleae, J. Ag. in Linn. vol. xv. p. 23. Aly. Medit. 

 p. IIG. Endl. Gen. pi. 3, Suppl. p. 44. Harv. Ner. Austr. 

 p. 9. Rytiphlaea;, Dne. Class, p. 02. Ceramieae, Chon- 

 drieaj, and Thamnophorese (in part) and Anomalophylleae, 

 Dne. I. c. Dasyeae, Polysiphonieae, Chondrieae (partly), Bo 

 tryocarpese (partly), Amansiea), Rhytiphl^eaceae, Carpoble- 

 pharidea) (partly), and Claudieae, Kdlz. Phyc. Gen. 414 — 

 451. Rhodomeleae, Lindl. Veg. Kingd. p. 25. 



Diagnosis. — Red or brown-red seaweeds, with a leafy or 

 filiform, areolated or articulated frond, composed of polygo- 

 nal cells. Fruit double : 1. Conceptacles (ceramidia) exter- 

 nal, ovate or urn-shaped, furnished with a terminal pore, and 

 containing a tuft of pear-shaped spores : 2. Tetraspores im- 

 mersed in distorted rarauli or in lanceolate receptacles 

 {stichidia), usually in rows. 



Natural Character. — Root mostly a simple disk, in some 

 accompanied by creeping fibres ; and in some the principal 

 stems are prostrate and creeping, the branches erect. Frond 

 very variable in aspect (if we take in the exotic forms of the 

 order) ; sometimes forming a net-work, sometimes filiform. 

 The leafy forms of the order are more numerous in the seas of 

 warm countries, and exhibit, as we approach the tropic, 

 leaves of more perfect formation. The flat, thin frond, with 

 its obscure midrib, of our Odonthalia, which is the nearest 



