with columella, tertiaries shorter, inner edges free. Tdar- 

 gins of first two cycles exsert. Septal margins dentate, 

 sides finely granulate. Columella well developed from 

 interlacing septal processes, one third diameter of calice. 

 Endothecal dissepiments thin, exothecal dissepiments 

 thick, both horizontal, 



34. Tdontastrea braziliana (Verrill) . 



Also Orbicella braziliana, (Verrill 1902), also Or- 

 bicella cavernosa, (Quelch 1886). 



Forms rounded masses up to 2 feet in diameter. 

 Differs only from !M. cavernosa in having strongly 

 blistered appearance between cups and in more uniform 

 thickening of septa. Brazil only. 



According to Quelch, this differs from O. cavernosa 

 only by ^he highly vesicular exotheca, which hides the 

 iostae and in the uniform thickening of the septa. 



35. Mcntastrea cavernosa (Linnaeus), (Plate 27). 

 Also Orbicella cavernosa, (Vaughan, 1919 and Ver- 

 rill, 1902). 



Described by Vaughan (1919) , page 380. 



Forms boulders which may be over 5 feet across. 

 Large cups, average 8 mm across, usually projecting 

 above surface. Septa prolonged into space between 

 cups. Rare in Bermuda but common in Florida, the 

 Bahamas and the West Indies. 



Corallum massive, growing to considerable size, up- 

 per surface flat, irregularly convex or domed. Calices 

 more or less elevated, diameter 5 to a mm close 

 together or separated as much as 6 mm. Costae well 

 developed, denticulate, rounded, about 48. Septa 48, 

 exsert, serrulate, in four cycles, those of first three reach 

 columella, others may be reduced or lacking. Columella 

 well developed, broad, with a papillany upper surface. 



90 



