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RED SEA-WEEDS.-RHODQSPEIIMEJE. 



Order VII. KHODOMELACE.E. 



Red or Brown-red or Purple Sea-iveeds, with a leafy, or thread- 

 like, or jointed frond composed of many-sided cells. Fruc- 

 tification of two hinds on different plants : — 1. Pear-shaped 

 spores in external ovate or urn-shaped conceptacles. 2. 

 Tetraspores lodged either in distorted branchlets or in 

 receptacles, called stichidia. 



Genus XXXVI. ODONTHALIA. 



Frond flat, thickish, disticbously branched, indistinctly 

 midribbed, alternately toothed at the margin. Spores in 

 marginal, stalked, egg-shaped, wide-mouthed conceptacles ; 

 tetraspores tripartite, arranged in double rows in marginal, 

 stalked, lance-shaped stichidia. — Odonthalia, from the? 

 Greek odous, & tooth, and thalos, a branch. 



All the species of this genus are natives of cold lati- 

 tudes; one is common to the northern shores of Eu- 

 rope and America, and the remainder have only been 

 found on the north-east coasts of Asia. 



Odonthalia dentata. Toothed Odonthalia. 



Fronds rising from a hard disc, tufted, from three to 

 twelve inches high, much branched, having a midrib in the 

 lower part, and becoming flat and membranous above ; 

 branches springing from the axils of the teeth of the main 

 stem, tapering at the base, deeply pinnatifid. Fructification 



