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208 BULLETIN: MUSEUM OF COMPARATIVE ZOÖLOGY. 
lands than now exist, — probably in the region now covered by the 
Pacific waters in the south, or the regions of the submerged: Mosquito 
and Roncador banks to the north. The lay of the formations indicates 
that the shore line was in the direction of the Pacific rather than the 
Caribbean, and this one fact, together with other considerations, may 
lead to the conclusion that land once existed off the Pacific side of Equa- 
torial South America, and the submerged Mosquito banks did not then 
exist in their present geographic outlines. 
But what was the source of these land derived sediments in tho An- 
tilles? At first it might be answered that the degradation of the Creta- 
ceous voleanoes alone might account for this material ; but, although the 
formation contains much volcanic material, it also has in it mica schists, 
quartz, and other débris foreign to the composition of the Antillean 
Cretaceous eruptions. Besides, the wide uniformity and assortment 
cannot entirely be satisfied by this hypothesis. On the other hand, the 
study of this material, considered from any point of view, suggests the 
hypothesis that the present Post-Cretaceous material was deposited 
upon the margin of pre-existing land areas lying to the north ward, of 
which they were a part, including the south point of Florida, the 
Bahama banks, all of which may have been remnants of the northern 
part of the hypothetical Windward Jurassic bridge or Archipelago, and 
that these lands during this epoch were being base levelled and subse- 
quently completely concealed by succeeding phenomena. 
The presence of this land-derived material in the fundamental Scotland 
beds of the oteanic island of Barbados is indeed perplexing. The oldest 
formations of this little island, standing solitary and alone in the Atlantic 
Ocean, are clearly composed of the débris of a former land, of which there 
is now no track or trace unless it be the deep submerged ridge extending 
northward from South America. We search in vain the visible structuro 
of the adjacent Windward Islands over a hundred miles to the west- 
ward, and separated by a deep submarine trough, for a solution, but can 
establish no connection between them. The only hypotheses entertain- 
able are that they were either derived from a land now submerged, which 
constituted the eastern bank of the Windward platform, or from a penin- 
sula which at that time may have extended out from the northeast corner 
of South America. If the latter conclusion is tenable, may we not also 
suppose that the Aves Island bank is also a relic of this old Cretaceous 
Windward land! i 
The early Eocene base-levelling was the beginning of initiation of ® 
subsidence which took place in the latter part of the Eocene and early 
