226 Christmas Island. 



ON THE rOEAMmiFERA OF THE 



ORBITOIDAL LIMESTONES AND EEEF ROCKS 



OF CHRISTMAS ISLAND. 



By Professor T. Rupeet Jones, F.R.S., etc., and 

 Frederick Chapman, A.L.S., F.R.M.S., etc. 



(PLATES XX AND XXL) 



The following has been written in elucidation of the foraminiferal 

 fauna of the rocks of Christmas Island (Indian Ocean), which 

 Mr. Andrews has kindly handed to us for description. 



In submitting this report we wish to state that we have made 

 it as comprehensive as possible in the time at our disposal, and 

 hope at a later date to furcish further details with regard to this 

 interesting collection. 



For the greater part of the work we have of necessity been 

 dependent upon thin sections for our study and determination of 

 the organisms ; and this at best is somewhat unsatisfactory. It 

 is hoped, however, that by a careful examination of the various 

 slices of rock, showing the organisms in their different phases, 

 the facts here brought together will in some measure extend the 

 knowledge of the association and habits of growth of these small, 

 but most important, rock-builders. 



It is now proposed to describe the general microscopic structure 

 both of the fossil and the recent limestones, in their order of age 

 as far as possible ; and to give concise accounts of any foraminifera 

 which appear to be new. 



Tertiary Limestones of Flying Fish Cove. 



The most complete section of the older rocks of Christmas 

 Island is that seen in Flying Fish Cove ; and for this reason 

 we chiefly confine our remarks to the foraminifera of the rocks 

 from this locality. 



The oldest bed exposed is a yellow limestone (No. 2).^ This 

 appears to be of much earlier date than the limestones found 

 higher in the sections. Orhitoides are found in all the limestones 

 of this section ; but those of No. 2 are of the type associated 

 with rocks of Nummulitic (Eocene and Oligocene) age, whilst the 

 Orbitoidal limestones which follow are probably of Miocene age. 



These numbers are those employed in Mr. Andrews' collection of rocks. 



