88 CORALS AND CORAL ISLANDS. 
cretes the axis within, it gives out buds externally; thus the 
branch rises. New branches commence at intervals over the 
sides of the rising stem or branch through the starting of new 
TALE y) 
1 Mian 
Ui 

ISIS HIPPURIS, LINN. 
budding centres, and so, finally, the Gorgonia zodphyte is 
completed. 
In a few species, the axis is partly or wholly calcareous. 
In the Isis family, it is made up of a series of nodes and 
internodes. The former, in the genus Isis, are white, calcare. 
ous, furrowed or fluted pieces; and the latter are smaller and 
horn-like in nature, as illustrated in the preceding figures. 
In the branching stem here figured, the main stem and the 
branch on the left are simply the axis, bare of the polyp-layer 
