122 
THE OCEAN WORLD. 
I. THE TUBIPOUIN2E. 
form a group consisting of several species, 'which live in the bosom of 
tropical seas, in which the Coral Islands form so prominent a feature. 
The group is exclusively formed of the curious genus Tubipora. 
The Tubipora is a calcareous polypier, formed by a combination of 
distinct, regularly-arranged tubes, connected together at regulated dis- 
tances by lamellar expansion of the same material. The aggregate for- 
mation resulting from this combination of tubes constitutes a rounded 
mass, which often attains a very considerable size. In Fig. 41 we 
have a representation of the zoophyte Tubipora musica and its 
product, which is sometimes designated by the vulgar name of Sea- 
Organ. In the engraving, 1 is the calcareous product, reduced to half 
its size ; 2, is a portion in its natural size ; 3, the tubes magnified, and 
containing the polype which occupies the summit of the tube, the 
Fig. 41 . 1 ubipora musica (Linn.), half the natural size. 
whole of which constitutes this curious polypier ; 4, is the polype mag- 
nified ; 5, the head or collection of tentacula of the individual polype- 
