134 ZOOPHYTES. 



CHAPTER IV. 



THE SERTULARIA. 



The preceeding observations on some of the Zoophytes already shew 

 the very comprehensive signification of their name, as applicable to a large 

 proportion of the animal creation. Within its sphere are included, soli- 

 tary, simple, naked, and unprotected creatures : it also embraces social, 

 complex, and well-sheltered beings, whether of pure organic formation or 

 combined, as we shall see, with inorganic matter of opposite elements. 



On quitting the fistulous Tubularia, where the delicate hydra, con- 

 tinually exposed to danger, is denied a receptacle for protection, we reach 

 another race, the Sertularia, where it has always a safe retreat, within 

 something whose substance may be compared to membranaceous texture. 

 Again, leaving the Sertularia, we come to other tribes, for which Nature 

 has furnished a strong calcareous dwelling. 



We shall find, however, in the progress of our enquiries, that the con- 

 figuration of the tenant sometimes undergoes a remarkable change, ac- 

 cording to the substance of the inorganic portion allotted for its habita- 

 tion. 



The intimate resemblance of the hydra, I should say the identity of 

 that animal, combined with inorganic parts so different that we might be 

 scrupulous of allowing them a kindred place, is very strange. At first 

 sight there seems no common resemblance between two of the hydraoidal 

 Zoophytes, they are so far asunder. Neither is this less singular in the 

 Ascidian genera, where, of two which are beautifully displayed, we observe 

 the abode of one amidst a gelatinous mass, the other amidst a membrane, 

 and a third, perhaps, retreating within a shell — all originating with them- 

 selves, and augmenting as they are enlarged. 



