CORALLINES. 



121 



Zoologists of the last century confounded all the species of this 

 genera inhabiting the tropical seas, making only one species, to which 

 they gave the name of Tubipora musica. But it is now known that 

 there are many species of Tubiporw, readily distinguishable in a fresh 

 condition by a difference in the colour of the polyps. The tissue of 

 these singular beings is of an intensely red colour. The disposition of 

 their tubes in the style of organ pipes has always attracted the atten- 

 tion of the curious inquirer into the secrets of Nature. 



II. GORGONIAD^E. 



Milne Edwards divides this order into three natural groups : I. The 

 Gorgoniadte. II. The Isidians. III. The Corallines. 

 The Gorgonians are composed of two substances : the one external, 



Fig. 42. The Sea Fan, Gorgonia flabellum (Linn.). 



.sometimes gelatinous and fugitive ; sometimes, on the contrary, creta- 

 ceous, fleshy, and more or less tenacious. Animated with life, this 



