/ 



88 A NATURALIST ON DESERT ISLANDS. 



and also other examples of Foraminifera, which could not 

 be named. 



All the genera mentioned above are common, and 

 possibly shallow- water forms, and Dr. Andrews informs 

 me that Mr. Mukler is inclined to regard them as fossil, 

 but cannot determine their geological age. All that can 

 therefore be said at present, is that the extremely soft and 

 finely-divided earthy deposit, which underlies the coral 

 capping on Swan Island, is a marine deposit containing 

 the remains of certain Foraminifera. Nor is there any 

 evidence, so far, to enable us to say at what geological 

 age it was laid down and subsequently elevated. 



With regard to the oceanic deposits of Barbados, Mr. 

 Gregory* was inclined to consider them "as of com- 

 paratively recent date, either Pliocene or Pleistocene " : 

 but we have already seen that the presence of radiolarian 

 ooze in these deposits is considered to be proof of the one- 

 time presence of Pacific waters in this region, for no 

 radiolarian ooze is found in the Atlantic. If, therefore, 

 it is correct to say, as Dr. Gregory has himself statedt 

 that the Atlantic and Pacific oceans have never been 

 united since the final emergence of Central America in 

 early Miocene, or possibly Oligocene times, the age 

 allotted by him to the oceanic deposits of Barbados 

 seems for this rea^^on, to say nothing of others, far too late. 



Mr. Spencer :|: puts the age of these deposits as between 

 that of the " Scotland " sand-stones of Barbados (deposited 

 in Eocene times or before) and the white coral limestones 

 which lie above them. These limestones he refers to the 

 Oligocene period. 



In Cuba there occur oceanic beds which appear to have 

 been deposited dm'ing local depressions to abysmal 

 depths in vr before the Miocene period, § and these oceanic 

 beds contain Badiolaria. These deep-sea radiolarian 



* Quart, Journ. Geol. Soc, Lond. 



t Quart. Journ. Geol. Soc, 1895. Vol. LI., p. 255. 



+ Quart. Journ. Geol. Soc, 1902. Vol. LVIII., p. 357. 



§ Bull. Geol. Soc. Amer., Spencer. Vol. VII., 1895, p. 94 



