sometimes lie flush with the surface (Plate 9) . In other 

 branching corals the cups project noticeably from the 

 surface (Plates 2, 3, 28) . 



The cups of some corals are well separated (Plate 31) 

 by the general coral surface, but in others their walls 

 are united to form a common boundary (Plates 7, 10, 

 13, 36) . They may also be fused longitudinally to form 

 valleys as in the brain corals (Plates 14, 15, 16, 17). 

 The diameter of the cup or the width of the groove 

 from wall to wall is used as an aid to quick identification. 

 The walls themselves may be thin, or in some cases 

 they are wide and may develop a groove. (Plate 16). 



The septa or partitions which project from the walls 

 towards the center of the cup or groove are not all of 

 the same size and they also vary in their distance apart. 

 Care should be taken to count both long and short 

 septa in determining the number of septa per centimeter. 

 Edges of the septa may be smooth (Plates 29, 30, 33) 

 or toothed (Plates 1 , 13, 26, 34, 37) and irregular. At 

 the inner edge of each septum there sometimes occur 

 small plates or lobes, which are known as pali (Plate 

 10) . In the centre of the cup a simple axial rod (Plate 

 1) is developed in some corals. This is the columella, 

 which varies in form from a solid rod to a more diffuse 

 structure. In a number of corals the upper edges of the 

 septa extend outside the boundary of the cup over the 

 general surface of the coral between cups. This condition 

 is known as costate (Plate 27) . 



Occasionally difficulty may arise in identifying young 

 corals. Young stages often consist of single cups, even 

 though the adult is more complicated. Where this is 

 likely to lead to confusion illustrations and descriptions 

 of the young stages are given. Another possible source 



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