CHAPTER VI 



THE POLYZOA, OR BRYOZOA 



THIS group has been sent from pillar to post by different 

 authorities, some of the older zoologists placing them with 

 the zoophytes. Others have classed them, together with, 

 as we shall presently see, totally different groups of animals 

 viz. the Tunicata and Brachiopoda, forming a large 

 group, which they termed Molluscoidea, which is un- 

 doubtedly a mistake, for later researches have shown 

 characters in the included forms which prove them to be 

 very diverse indeed. 



In fact, the Tunicata or Ascidians are now advanced to 

 the same Phylum as the vertebrates ; and this not from 

 fancy, but from prolonged and careful study of their em- 

 bryology and their affinities. 



The Polyzoa seem to be very nearly related to the 

 worms. 



They are thus denned : Animals of small size, usually 

 united in colonies, living within a structure which, like the 

 zoophytes, they build up, and which is termed a Polypary. 

 This structure is of horny or limy substance, and often of 

 exquisitely beautiful design. 



The animals have a retractile crown of ciliated tentacles. 

 They have an alimentary canal, and a simple nerve system. 

 There is an immense number of species, and they abound 

 on all our shores. 



Flustra foliacea, or common " Sea-mat," which looks like 

 a bunch of rather crisp fucus, is a very familiar example, 

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