18 



GUIDE TO THE CORAL GALLERY. 



High Wall 



Case 



E. end of 



^.Gallery. 



as to give a reddish colour to the surface of the sea in daytime. Tu 

 the Persian Gulf, a richly pigmented variety occasionally forms on 

 the surface of the sea brilliant scarlet bands, which extend for manv 

 miles. 



CiLIATA. 



The members of this group are characterised by the presence of 

 cilia on the surface of the body. These organs may form a spiral coil 

 round the anterior end of the body in relation to the mouth, or they 

 may be distributed over the whole or part of the surface of the body. 

 Garchesium polypinum (Plate XII. in the Case), which belongs to the 

 group of " Bell Animalcules," occurs in ponds in the form of bluish 



Fig. 14. 



Stentor polymorphus, tlie Trumpet Polypus. (Magnified.) 



mucilaginous filmy patches on fresh-water plants, pieces of wood, &c. 

 The branching fan-shaped colony is highly contractile, and shrinks 

 into a spherical ball on being alarmed. Each individual has a 

 bell-shaped body seated on a stalk. The cilia, which form a 

 spiral fringe round the anterior end, set up a vortex in which food 

 particles are carried through the funnel-like mouth and gullet 

 situated inside the rim, and thence into the interior of the bodv. 

 VorticoUa nelndifera (Fig. 13) also forms colonies ; the figure shows 

 the individuals in various phases of contraction. Some species of 

 Bell Animalcules are solitary and do not form colonies. Stentor 



