24 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
the Central Mountains. "The highest summits of the plateau are found 
in the crests surrounding the Clarendon basin, near the centre of the 
island, which attain a maximum altitude of about 3,000 feet or less than 
one half that of the highest Blue Mountain peaks. The highest of the 
plateau remnants is Mount Diablo, which forms the divide between the 
two coasts as well as between St. Thomas and Clarendon valleys. It is 
reported to be 3,053 feet in altitude. Altitudes exceeding 2,000 feet 
continue southward from the west end of the Clarendon Valley almost 
to the southern coast of Manchester and St. Elizabeth. Some of these 
are given by the official surveys as follows : Mocha, 2,558 feet; Cabbago 
Hall, 2,983 feet; Drayton, 2,210 feet; Sedburg, 2,269 feet ; Mason’s 
Run, 3,000 feet; Craig Head, 2,619 feet; Aboukir, 2,019 feet; and 
Water Mount, 1,844 feet. Don Figuera Mountains, over 2,400 feet, 
Mile Gully Mountains, 2,514 feet, and Carpenter's Mountain of Man- 
chester, 2,400 feet, are also remnants of this old plateau level, near the 
south coast of the central region. On the east the John Crow Ridge 
(alt. 2,110 feet), an elongated summit extending parallel to the coast, may 
be either a remnant of the old summit level or the oldest and highest of 
the base level plains cut out of its marginal topography. On the south 
side of the Blue Mountain Ridge the highest summit of Yallahs Mountain 
(alt. 2,254 feet) is the sole surviving remnant of the old summit topog- 
raphy of that side of the island. These elevations indicate that the 
region of maximum altitude of the plateau was in the widest part of the 
island from near the south coast of Manchester to and just across the 
boundary of St. Ann. 
In places along the south coast there are isolated white limestone 
remnants of the plateau, which are separated from the main body by 
the wide indentations of the lower lying Coastal Plains. The Port 
Henderson and Healthshire Hills of St. Catherine, and the Braziletto 
Mountains and Portland Ridge of Clarendon, are of this type. 
The materials of the plateau and its outliers are soluble limestones, — 
old sheets of calcareous oceanic sediments now chalky or suberystalline 
in texture, which were deposited upon and around the bases of the Cen- 
tral Mountains and attained their present altitude by a subsequent ele- 
vation. These white limestones are described elsewhere in this paper 
under the names of the Montpelier, Moneague, and Cobre formations. 
The details of the configuration are largely due to the peculiar solvent 
character of the limestone. These hills, especially in the interior, owe 
their configuration largely to the agency of solution, while the forms of 
the Central Mountains are due entirely to denudation. So important 
