Fossil Corrtls. 



217 



The Christmas Island specimens differ from Milne Edwards 

 and Haime's diag-nosis in three respects, which appear to me to be 

 ■worthy of at least varietal recognition. 



Var. columnata,' nov. 



The variety differs from the typical form of the species by 

 having deep open calices ; the columella is very large ; and the 

 tertiary septa are not united to the secondary septa. 



The diameter of the corallites is from 11-13 mm. ; the diameter 

 of the columella is about 5 mm. ; and there are about 3-^ cycles 

 of septa. 



Disfribtition. 



a. Kecent : 



Locality of the type unkno^vn. 



b. Fossil : 



Christmas Island. No. 322. Limestones of the sea- 

 cliff series, mouth of Sidney's Dale. 

 Figure. — Fig. 3. Part of a transverse section, x H <iif>. 



Fig. 3. 



Orbicella prseheliopora, sp.n. 



Diagnosis. — Corallum massive : external characters unknown. 

 Corallites of medium size, being from 4-5 mm. in diameter, circular, 

 and separated by from 1 to 2 mm. Columella very spongj'-, but 

 large, being from 1-1-5 mm. in dia. Septa irregular; in some 

 sectors of a corallite there may be representatives of an incomplete 

 sixth order; whereas in the adjacent sector the septa of the fourth 

 order are rudimentary and barely recognizable. The primary and 



1 Columnatuf, furnislied with a column, in reference to the large columella. 



