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200 BULLETIN: MUSEUM OF COMPARATIVE ZOÖLOGY. 
excellence, by failing to correlate the threefold testimony of config- 
uration, biology, and geology have been led into serious errors of 
deduction. 
Vague indeed is knowledge of the history of tropical regions prior to 
the Cretaceous period. Rocks of an earlier epoch are but sparsely and 
imperfectly exposed, being concealed even where they probably occur by 
the overlay of later sediments and volcanic ejecta. We know that the 
Appalachian and allied regions of the United States, as far west as the 
98th meridian, since Paleozoic time, have been great bulwarks of land, 
against the southern front of which the northern waters of the Gulf of 
Mexico extended in Cretaceous and Eocene time, and that these old 
lands prior to their degradation and burial in late Mesozoic time occu- 
pied much of the southern and eastern Coastal Plain. There are also 
areas of old Mesozoic land of smaller dimensions in the Cordilleran 
regions of northwestern Mexico and the southwestern United States. 
In southern Mexico, Guatemala, and possibly Cuba and Haiti, there are 
long east and west ridges of Paleozoic rock, which may have had some 
fundamental relation to the east and west trends so largely dominating 
in the tropical region, or possibly foreshadowing the present outlines of 
the Great Antilles. In northern Venezuela another stretch of Paleozoic 
or Archean rocks is reported to extend from the Andes north of east 
to the Caribbean coast and through the island of Trinidad. Paleozoic 
rocks also probably occur beneath the voleanic débris of Central America 
in Nicaragua, Honduras, and Costa Rica. The oldest rocks of Cuba and 
Haiti have been doubtfully considered of Paleozoic origin. Such are the 
earliest foundations of the great tropical amphitheatre in which during 
Mesozoic and Cenozoic times conflicts between land and ocean have con- 
tinued, and from which amidst the vicissitudes of migrating shore lines, 
great oscillations of level, and volcanic extrusions, the present configura- 
tion of land surfaces and ocean bottoms have been evolved. In all of 
these localities south of the United States the events of Paleozoic and 
older Mesozoic history have been obliterated by the overwhelming phe- 
nomena of Cretaceous and later time, — buried beneath the oceanic sedi- 
ments or volcanic ejecta, so that the interpretable history of the region 
maybe said to begin with Cretaceous time. 
There is some evidence that during the long period between the Ap- 
palachian revolution, after the close of the Carboniferous and the begin- 
ning of the Lower Cretaceous (Wealden epoch), the Atlantic borders of 
the North American coast met the Atlantic Ocean far eastward of the 
present continental outline, and that this expansion of the land was at 
