90 C0RAL8 AND CORAL ISLANDS. 



In the Corallidce, the axis is wholly calcareous, and firm and 

 solid throughout, with usually a red color, varying from crim- 

 son to rose-red. Here belongs the Cor allium rubrurn, or pre- 

 cious coral. The polyp-crust or cortex, which covers the red 

 axis or coral, is thin, and contains comparatively few calcare- 

 ous spicules, and consequently it readily disappears when the 

 dried specimens are handled. In an uninjured state, the polyp 

 centres may be distinguished over it by a faint six-rayed star. 

 A branch from a specimen obtained by the author at Naples, 

 is represented, of natural size, in the cut on page 89. The pol- 

 yps, as the enlarged view, by Lacaze Duthiers, shows, are sim- 

 ilar to those of other Alcyonoids — the tentacles being eight in 

 number and fringed. The figure represents the extremity of 

 a branch, magnified about four times lineally, with one pol- 

 yp fully expanded, two partly, and the rest unexpanded. In 

 the living Corallium, they open out thickly over the branches, 

 and make it an exceedingly beautiful object. The coral grows 

 in branching forms, spreading its branches nearly in a plane ; 

 and sometimes the little shrub is over a foot in height. The 

 author just mentioned states that, among the polyps, those 

 of the same branch are often all of one sex alone, and that, be- 

 sides males and females, there are a few that combine both 

 sexes. 



The precious coral is gathered from the rocky bottom of 

 the borders of the Mediterranean, or its islands, and most 

 abundantly at depths of 25 to 50 feet, though occurring 

 also even down to 1,000 feet. There are important fisheries 

 on the coast of southern Italy ; of the island of Ponza, off the 

 Gulf of Gaeta ; of Sicily, especially at Trapani, its western ex- 

 tremity ; of Corsica and Sardinia, in the straits of Bonifacio ; 

 of Algeria, south of Sardinia, near Bona, Oran, and other 

 places, which in 1853 afforded 80,000 pounds of coral; and on 



