126 BRITISH SEA-WEEDS. 



brancblet, and are furnished with a terminal pore. — Co- 

 ealltna, from the Latin coralium, coral. 



This is the most highly organized British genus of this 

 very peculiar Order of plants. The species which it 

 contains, and those of the two next genera, were for- 

 merly considered to belong to the Animal rather than to 

 the Vegetable Kingdom, and were accordingly classed 

 among corals and corallines, and their external appear- 

 ance fully justified such an arrangement. Their fronds 

 are composed of ordinary cellular tissue ; but this is so 

 completely coated with carbonate of lime as to give the 

 whole plant a rigid, stony, coral-like structure, and it 

 is not until this coating has been removed by soaking 

 the fronds in acid that the vegetable tissue is visible. 



The fronds are divided into articulations, or internodes 

 of very unequal length and varied shape, these are con- 

 nected by joints or nodes, which are flexible, being formed 

 of cellular tissue free from calcareous matter. The 

 fructification is peculiar, and not yet fully understood. 

 Organs which are almost perfectly analogous to tetra- 

 spores are found in conceptacles which are identical in 

 form and origin with those which contain the spores of 

 other genera. 



Corallina officinalis. The medicinal Coralline. 



Fronds many times pinnate, growing in large numbers 

 together on rocks or sea-weeds at various depths ; articu- 

 lations of the stem, cylindrical, about twice as long as broad, 

 of the branches, more or less wedge-shaped, with rounded 

 shoulders, and of the branchlets linear, cylindrical or 

 slightly flattened. Fructification in conceptacles formed 

 either from a terminal articulation, or on the surface of the 

 frond. 



