72 A HALF-HOUK WITH THE 



tifiillv radiated structure. This is seen at figure 

 151, plate 5. The suckers, also, of the same animal 

 present little rosettes, surrounded by a very delicate 

 hyaline disk, represented at figure 152. Upon the 

 surfaces of both star-fishes and sea-eggs will be 

 found little moveable bodies which are called pedi- 

 cellarice.^ In the sea-egg they possess three moveable 

 nipper-like limbs, whilst in the common star-fish 

 they present only two. These are represented at 

 figures 153 and 154, plate 5. A controversy has 

 been raised on the question as to whether these 

 bodies are parasitic animals, or part and parcel of 

 the structure of the creature on which they are 

 found. As they are so constantly present, they are 

 undoubtedly parts of the animal on which they are 

 found. The movements of the nippers are very 

 active, and they frequently lay hold of objects 

 which pass near them. 



As common on the shore as the polypidoms of 

 the polyps, are the animal skeletons called, in some 

 parts of the country, sea-mats {Flustra foliacea). 

 When placed under a low power, and viewed by 

 reflected light, the sea-mat is composed of little 

 cavities or cells, seen at figure 162, plate 6. In 

 .each one of these is seated a creature of much more 

 complicated organization than the polyps just ex- 

 amined. It has, it is true, a ring of tentacles ; but 

 if these are examined, the tentacles are found to be 

 covered with cilia, as seen at a, in figure 163, 

 plate 6. This family of creatures are called Polyzoa, 

 or Bryozoa, and form a group of animals which are 

 classed with the Mollusca, or shell-fish. Sometimes 

 these creatures attach themselves to sea-weeds, 

 oysters, stones, and other objects at the bottom of 

 the sea, forming a kind of cellular membranous 

 expansion. Such are the species of Lepralia, 

 figured at 155. Sometimes the cells are elongated 



