156 CERAMIACE^:. 



ORDER XIII. CERAMIACE^E. 



Ceramics, J. Ag. Alg. Medit. p. 69. EndL 3rd Suppl. p. 

 34. Dne. Class, p. 62 (in part). Callithamnieae and Ceramieae, 

 Kutz. Phyc. Gen. pp. 370, 378. Cerameae, Lindl. Veg. 

 Kingd. p. 25. 



DIAGNOSIS. Rose-red or purple sea-weeds, with a filiform 

 frond, consisting of an articulated, branching filament, com- 

 posed of a single string of cells, sometimes coated with a 

 stratum of small cells. Fructification: 1, favella ; berry- 

 like receptacles, with a membranous coat, containing nume- 

 rous angular spores ; 2, tetraspores attached to the ramuli, 

 or more or less immersed in the substance of the branches, 

 scattered. 



NATUEAL CHARACTER. Root small and discoid, some- 

 times creeping. Frond of small or mediocre size, almost 

 always filamentous, generally filiform and cylindrical, rarely 

 compressed or flat (in some species of Ptilota\ narrow, much 

 branched and mostly pinnate : in some cases dichotomously 

 divided. In the simplest forms of this order (as Callitham- 

 iriori) the frond consists of a single string of cylindrical cells, 

 one growing from the apex of another, and forming branches 

 by cells budding from points just below the apex of the pre- 

 viously formed cell. This structure prevails through the 

 whole frond of the smaller Callithamnia, but in the larger 

 species, the lower part of the branches and the whole of the 

 stem are strengthened with numerous internal filaments tra- 

 versing the frond ; and in the shrubby species the stems are 

 quite opake, and seem composed of a multitude of longitudi- 

 nal filaments closely packed together. But even in these 

 compound structures the frond has at first been organized as 

 a simple string of cells, and will always be found to be tra- 

 versed by an articulated filament, which is the original 

 branch or stem, round which the longitudinal, secondary 

 threads have been subsequently developed. These secondary 

 or strengthening strings of cells appear to be formed at the 

 bases of the upper branches, and to extend downwards, in a 

 manner perfectly analogous to the formation of wood-bundles 

 in a vascular plant. In such species as Cal. tetragonum and 

 C. brachiatum the gradual introduction of such strengthen- 

 ing filaments may readily be traced by selecting specimens 



