MUSEUM OF COMPARATIVE ZOGLOGY. 249 
marly or very slightly siliceo-argillaceous beds. The limestone beds 
have been well described lithologically by Sagra, as follows :— 
“It is white in color, or light yellow, with a fracture sometimes smooth, 
sometimes conchoidal, containing some concretions, — very often casts with 
petrifactions. The fossil substances enclosed in the limestones are very abun- 
dant. . . . The porous beds of the middle part of this locality, as near Batabano, 
resemble those spongy and calcareous banks of the Jurassic of Francone, near 
Dondorf, Pegnitz, and Tumbach. These yellow cavernous beds, which show 
cavities from four to five inches in diameter, alternate with others entirely com- 
pact and less charged with petrifactions. ‘The line of hills which border the 
valley of Los Guines toward the north, and which unite the hills of Camoa 
and the Tetas de Managua are of this last variety, the color of which is a rosy 
white, sometimes almost lithographic, like the Jurassic limestone of Pappenheim. 
The compact and cavernous beds contain small ferruginous masses, and are the 
same formation that Humboldt designated the Calcarie de los Guines, which is 
exposed on the southeast near Trinidad, on the hills of San Juan, already 
referred to, and on the north coast, near Matanzas. In these different localities 
it exhibits grand subterranean cavities, where rain water accumulates, and in 
which many considerable streams submerge.” } 
I might add to this description the remark that these rocks bear a 
striking lithologic and structural resemblance to the Neocomian and 
Middle Cretaceous rocks of Texas. 
Although distinctly stratified, the limestone is irregular in texture. 
While it is, in general, of a cellular structure, a cubic foot of it in any 
locality exhibits great irregularities in hardness and compactness. There 
are spots so hard and crystalline that it is difficult to break them with 
a hammer ; other spots are firmly crystalline and banded ; still others 
are rounded indurations; and again there are soft, pulverulent spots. 
All of this irregularity of texture is secondary, or in a condition of 
alteration produced by aqueous solution. In some places the cellular 
cavities are many feet deep, while the remaining portions are indurated 
into sharp edges of coarse, sometimes crystalline limestone. So com- 
pletely has the work of solution and interstitial change gone on that it 
is doubtful whether the original nature of the rock is anywhere well 
preserved. 
This weathering and induration is very similar to that which I have 
often noticed in the chalky Lower Cretaceous limestones of Texas. On 
the resisting summit points the rock is hardened and worn into the 
peculiar Liliputian ridges known in the Alps as ‘“ Karrenfelder,”’ while 
1 Histoire Physique de Cuba, Tom. I. p. 109. 
