90 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
No. 963. The organic fragments in this limestone are quite fresh, 
and consist of Carpenteria, Polytrema miniaceum, Amphistegina, alcyo- 
narian spicules, echinid spines, and Lithothamnion. The organisms are 
for the most part invested with a coating of fibrous muddy calcite, and 
the remaining spaces have been filled with a mosaic of clear calcite 
crystals. 
No. 549. An orbitoidal limestone having a matrix of calcite. An 
incrusting deposit of calcite partially fills some cavities and cracks 
occurring in the rock. 
No. 571. An orbitoidal limestone similar to the last, but containing 
more ‘‘mud ” in the matrix. Some of the organisms have been altered 
to a brownish silt. Acute crystals of calcite project from their margins, 
and adjoining fragments have been cemented subsequently by large 
erystals of calcite. 
No. 845. A Lithothamnion limestone in which many of the organisms 
are represented by pseudomorphs in calcite. 
No. 595. Globigerina and small fragments of Carpenteria are abun- 
dant in this limestone, while calcite crystals fill cracks in the rock, and 
serve to cement numerous fragments of yellow palagonite. 
No. 840. A limestone containing Gypsina, Halimeda (1), and echinid 
spines. Minute volcanic fragments are scattered through the rock, which 
is rather cavernous. 
No. 2. An orbitoidal limestone containing, in addition, well-preserved 
Gypsina, Amphistegina, and Lithothamnion. 
Axpove Fryine Fisa Cove. Chemical. — Proceeding inland from No. 
664 at the top of the sea cliff, the level falls slightly at first, and three 
specimens collected along this gentle slope have been analyzed. No. 663 
is from about the same level as No. 664— namely, 750 feet — but is 
found to contain only 1.7 per cent of magnesium carbonate, while a little 
further inland, from a level of 710 feet (No. 657), yields 25 per cent. 
Quite close to this last limestone the surface of the ground is covered 
with a chalk-like deposit in which occur harder nodules. The centers 
of these nodules, represented by No. 658 a, consist of a compact lime- 
stone containing only 2 to 3 per cent of magnesium carbonate, while the 
soft crumbling exterior (No. 658 B) is highly dolomitic, containing no less 
than 39.5 per cent of magnesium carbonate. The association of these 
two rocks is very interesting, and would seem to suggest that the dolo- 
mitic rock may, in this case, arise by the concentration of magnesium 
carbonate, owing to the superior solubility of calcium carbonate in perco- 
lating water containing atmospheric carbon dioxide. Further back from 
