MUSEUM OF COMPARATIVE ZOOLOGY. 2(3 
with the sea are subjects concerning which I am at a loss to offer 
explanation. 
The geologic section (Plate I. Fig. 4) of the caiion shows that there 
are at least three alternations of old reefs and thin gravel beds, which in 
turn rest upon a great thickness, not less than eight hundred feet, of 
the older Tertiary limestones, out of which the amphitheatre proper is 
carved. The beds are all tilted to an angle of fifteen degrees, but the 
highest elevation of the undoubted coral laid down against the old 
limestone is less than one hundred feet. 
That this amphitheatre was once an indented harbor and the Yumuri 
River cafion its outlet, is a hypothesis which may he suggested. The 
denuded floor shows no trace of evidence that would convey this impres- 
sion, but around the walls of the amphitheatre are traces of terraces 
corresponding in height to the hundred-and-fifty-foot bench outside 
the harbor, and these may represent the former floor of the amphi- 
theatre when at sea level. If they do, then the Versailles, or highest 
elevated reef rocks, were formed off the point of an old outlet through 
the Yumuri. In the caiion itself, however, there is no distinct evidence 
of planation terraces, such as would indicate pausation periods followed 
by renewed epochs of cutting, although just out of it on the west side of 
the harbor, back of Versailles church, old river gravels are preserved 
about twenty feet above sea level. 
Between Havana and Matanzas the interior is a very broken country. 
The railway runs back of the interior of the escarpment of the old coast 
limestones, and sub-parallel to them, for thirty-six kilometers from 
Havana, upon a floor of underlying metamorphics, constituting a very 
hilly country. At thirty-seven kilometers the railway again cuts the 
bottom of the limestone at an altitude of two hundred feet, entering a 
level limestone plain at Aguacate, separated by a deep eroded valley 
from a range of limestone hills two kilometers to the north. At sixty- 
two kilometers the road cuts through this range of tertiary limestone 
hills, which have an altitude of six hundred feet. At Serba Mocha the 
peculiar limestone hills known as the Pan de Matanzas are seen to the 
north across an eroded valley. These summits are to the western half 
of the island what the Yunque is to the eastern, — remarkable isolated 
remnants of the nearly destroyed older levels which once surmounted 
the island. The Pan de Matanzas is alleged to be twelve hundred feet 
high. It consists of a double eminence, the intervening valley present- 
ing precipitous walls. The summits are of limestone, and are clearly 
remnants of the old limestone mass of the interior, from which they have 
VOL. Xvi. — No. 15. 18 
