Fossil Corals. 209 



Mussa aff. echinata, Cceloria andrewsi, Montipora aff. dance., etc., 

 should be regarded as Pleistocene or Pliocene, the evidence is 

 insufficient to show. It is only certain that these limestones are 

 intermediate in age between the late Pleistocene of the sea cliffs 

 and the ]?kIiocene of the central nucleus. 



Family POCILLOPOitlD-^. 



Pocillopora, aff. brevicornis, Lamarck, 1816. 



Pocillopora is represented among the Christmas Island corals by 

 several fragments included in a limestone from the foot of the 

 first inland cliff on the jS'orth Coast (]S'o. 867). One specimen 

 is a cylindrical branch 45 mm. high and 8 mm. in diameter. 

 Another is a low, massive, almost hemispherical branch. 



Mr. Bernard has provisionally identified two recent Pocilloporce 

 from Christmas Island as P. favosa and P. hrevicornis ; the fossil 

 specimens would agree with either in the characters of the 

 corallites. A large number of recent species of this genus have 

 been proposed by neontologists on variations in the shape of the 

 branches. Ortmann, ^ however, has suggested that the recent 

 species are mere individual variations. In describing a collection 

 of thirty - three specimens he states that they form a complete 

 transitional series, and fill up the gaps between the previously 

 described species. Ortmann, therefore, did not give a specific 

 name to any of the specimens. 



Recently Mr. J. S. Gardiner^ has also questioned whether "all 

 these so-called species should not rather be described as varieties 

 of one species," though he retains the conventional method of 

 treatment of the group. 



The most convenient name for the Christmas Island fossil 

 specimens would be P. hrevicornis, Lam. 



Pocillopora, sp. indet. 



]N'o. 989. From second inland cliff, over Flving Fish Cove ; 



alt. 500-600 feet. 

 jSTo. 947. Broad reef on middle of the island ; alt. 500-600 feet. 

 'No. 925. High cliff over south end of Flving Fish Cove ; 



alt. 400 feet. 

 These three specimens are so altered that they are specifically 

 indeterminable. 



^ Ortmann, Syst. und Terbr. Steiukor. : Zool. Jahrb., vol. iii, Syst. 1888, 

 pp. 162-165. 



' J. S. Gardiner, " Pocilloporidfe from S."W. Pacific": Proc. Zool. Soc, 

 1897 (1898), p. 942. 



