32 THE CANADIAN NATURALIST. [Vol. 



Yllo 



The white limestoDe of J;imaica, referred to by Sawkins (Geo- 

 logy of Jamaica^ London, 1SG9) to the Post-pliocene, covers more 

 than three-fourths of the Ishmd, and is computed at 2,000 feet in 

 thickness. It rests on the yellow limestone (Miocene) which, he 

 remarks, during the deposition of the former, '' sank to great 

 depths, in some places apparently 3,000 feet, so as to permit the 

 growth of those great coral structures, from the debris of which 

 the enormous development of the white limestones has been de- 

 rived. The lapse of time required for these importiint pheno- 

 mena cannot be easily realized by the imaginiition." Mr. Bland 

 proceeds to say ''that the islands, or some of them, were for- 

 merly united and formed part of an ancient continent, may, it 

 Avould seem for rarious reasons, be inferred."' lleferring to the- 

 Anguilla cave remains, Prof. Cope remarks (^FrocceJ. Acad, i^at^ 

 Sci. Phila. 1868) '' that the Caribbean Continent had not been 

 submerged prior to the close of the Post-pliocene, and that its 

 connection was with the other Antilles, while a wide strait sepa- 

 rated it from the then comparatively remote shores of North 

 America." Mr. Bland adds '' that the occurrence with the An- 

 guilla fossils of a land shell of a species now living, points to the 

 ao-e of the existing fauna, but the marked difference, both generic- 

 and specific, between the present land-shell fauna of the islands 

 upon and to the north and west of Anguilla bank, and those to 

 the south of it, may be taken as evidence of their early and con- 

 tinued separation." 



It is not a little remarkable that the Caribbean Continent,, 

 whose former existence is thus revealed to us, should have sa 

 nearly coincided in time with the Glacial Period in North Amer^ 

 ica. Could this mass of laud, the greater part of which re- 

 ceived its inhabitants from Mexico and Central America, have 

 closed the outlet of the Caribbean Sea ? The existence of such 

 a barrier would go far to explain the extreme cold of this period 

 in North America ; for had there been at this time no outlet from 

 the Caribbean Sea to the Gulf of Mexico, the tepid waters which 

 enter that sea on the east and pass out again by the Florida 

 passage and Gulf Stream, would have been compelled to com- 

 mence their journey northward at a point much further east 

 than they now do, and sow^ould not have flowed along the North 

 American coast, nor carried to Northern Europe the teniperature 

 of low latitudes. It is possible that the Antilles may have been 

 populated in successive stages from Central America and Yuca- 



