120 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
limestone a form of Orbitoides, only known elsewhere from Oligocene 
and Eocene rocks, while higher up in the series other forms of the 
same genus occurred, which were correlated with certain forms found 
in Java, Sumatra, India, and other localities from rocks of Miocene 
age. The highest rocks of the plateau were doubtfully referred by Dr. 
C. W. Andrews to the Miocene on the report of Dr. Gregory on the 
fossil corals. Since the publication of the monograph on the Island, 
more sections have been cut, and I met with Orbitoides from two rocks 
collected near Phosphate Hill, so that the Miocene age of the rocks of 
the plateau is now fairly well established. The age of the inland 
cliffs and fringing reefs cannot be fixed with certainty. The Forami- 
nifera, with the exception of rolled fragments of Orbitoides, all belong 
to forms still existing, but Dr. Andrews thinks that the upper inland 
cliff may be of lower Pliocene age, the lower inland cliff later Pliocene, 
while he assigns a Pleistocene age to the shore cliff. With regard to 
the rocks of the raised limestones of the Fijis, Tongas, ete., Mr. Agassiz 
maintains’ that they consist mainly of Tertiary masses of limestone, 
an opinion largely based on their altered appearance and their relation 
to the undoubtedly more modern fringing reefs and terraces which 
occur on some of their slopes. I am able to confirm this opinion by 
fossil evidence from two of the islands of the Fiji group. In Mango 
a form of Orbitoides occurs at a level of 310 feet, which Mr. Frederick 
Chapman kindly identified for me as Orbitoides swmatrensis, a Mio- 
cene form from Christmas Island, Sumatra, and Borneo. The rock in 
which it occurs is, therefore, presumably of Miocene age. 
One of the limestones from Namuka, another of the Fiji group, also 
contains a form of undoubted Orbitoides, which was, however, not cap- 
able of being specifically identified. It seems not unreasonable to 
suppose, that if more sections of these limestones were examined, the 
distribution of the genus Orbitoides over the islands in the Pacific 
would be still further enlarged. 
C. The literature in relation to the question of dolomite is so large 
that it would be quite impossible within the limits of this present paper 
to discuss the subject adequately, but it may not be out of place to 
summarize a few of the more important opinions, which from time to 
time have been put forward by chemists and geologists in explanation 
of its formation. Gustav Bischof? gave an admirable account of the 
1 Bull. Mus. Comp. Zodl., 1899, Vol. XX XIIL, p. 10. 
2 Chem. and Phys. Geology, 1859. 
