





RADIATA. 181 



blance to Actinia. Minute spicules of calcareous matter 

 are scattered throughout the mass. In Gorgonia such 

 spicules, with horny matter, make up a continuous 

 branching coral in the same plane, whose ramifications 

 unite in a beautiful net- work. (Fig. 81.) In Corallium 

 rubrum, the precious coral of commerce, the axis is of 

 stony hardness, and branching like a shrub. In the 



FIG. 82. Red Coral. 



FIG. 83. Tubicora Musica. Organ-pipe Coral. 



living state the branches are covered with a red cceno- 

 sarc, (common flesh,) studded with polyps. (Fig. 82.) 

 The feather-shaped sea-pens (Pennatula] have the ex- 

 tremities of their stems buried in sand. In some genera, 

 as, Virgularia, the stem is prolonged to between three 

 and four feet in length, while the polypiferous lobes are 

 comparatively short. The red organ-pipe coral of the 

 Indian Ocean, (Fig. 83,) with its table-like partitions and 



green polyps, belong also to this group. 

 16 



