CH4.PTEE VIII. 



MOLLITSCOIDA. 



Animals more or less resembling in structure either 

 the Sea-Mat (type of the Colonial MoUuscoida) 

 or the Lamp-shells. 



Classes. — Polyzoa, or Moss-corals. 



Bkachiopoba, or Lamp-shells. 



These are a group formerly classed with the MoUusca, 

 which develop from a larval form comparable with 

 that of some worms. 



The class BEyozoA, or Polyzoa, Moss-corals or Sea- 

 mats, resemble the Hydrocorallines in appearance, being 

 polyps with tentacles arranged round a circum-oral 

 disc called the lophophore, and usually disposed in 

 colonies ; but in reality they are very different. They 

 are distinguished from them by possessing an ex- 

 cretory opening (anus) and a body-cavity.^ They 

 reproduce themselves asexually as well as sexually — 

 the asexual germs, found in the fresh-water species, 

 being called statoblasts. The cuticle of each polyp 

 hardens into a cell, called the ectocyst : the coral- 

 like mass is built up by the adhering walls of suc- 

 cessive polyp-cells. The individuals bud while yet 

 in the larval stage. 



There are cases in which it is stated to be indistinguishable. 



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