Valleys under 10 mm wide and 6 mm deep. No ridges on wall. 

 Septa over 14 to the cm 31. 



31. Coral forms uneven masses with knobs or hillocks. Walls 

 never grooved, upper margin sharp. Septa over 30 per cm 

 (Plates 14^ 15) Viploria cUvosa (Ellis and 



Solander) 



KNOBBED BRAIN CORAL 

 Coral forms more or less even dome-shaped masses. Walls 

 less pointed and sometimes grooved. Septa less than 20 per cm 32. 



32. Walls always grooved above, width of groove varying. Septa 

 between 14 and 18 per cm (Plate 16) 



Diploria lahyrifithiformis (Linnaeus) 



BRAIN CORAL 

 Walls not grooved except rarely at edge of coral. Septa 

 between 15 and 20 per cm (Plate 17) 



BiphrUi sirigosa (Dana) 



COMMON BRAIN CORAL 



33. Cups 10 mm or more in width 34. 



Cups under 10 mm in width 35. 



34. Six to eight coarse teeth pointing obliquely upwards on edge 

 of each septum (Plate 36) 



Jsophyilastrea rigida (Dana) 

 ROUGH STAR CORAL 

 Numerous teeth on edge of septum pointing horizontally 



^ussismiUa hrasiUensis (Verrill) 

 BRAZILIAN FLOWER CORAL 



35. Cups under 5 mm wide but may be elongated up to length 



25 mm 36. 



Cups may be more or less than 5 mm wide. If less than 5 mm 

 wide they are never elongated beyond 5 mm 37. 



36. Walls of cups joined. Septa with distinct teeth 



7avia conferta Verrill 



GROOVED CORAL 

 Walls of cups separate and stand out from surface of coral. 

 Septal teeth very small (Plate 31) 



Vichocoenia stokesU Edwards 



and Haime 



STAR CORAL 



37. Septal edge smooth. Cups never over 2.5 mm 38. 



Septal edge with small teeth or beaded. Cups between t mm 

 and 5 mm wide 39. 



70 



