70 NOTES AND MEMORANDA. 
smaller chamber of Globigerina, and the outer wall as the 
equivalent of the large outer chamber of Globigerina deve- 
loped in this form as an investing chamber. Count Pour- 
tales, Max-Schultze, and Krohn, on the other hand, believe, 
on account of the close resemblance in structure between the 
two shells, their constant association, and the undoubted fact 
that an object closely resembling a young Globigerina is often 
found within Orbulina, that the latter is simply a special re- 
productive chamber budded from the former, and capable of 
existing independently. I am rather inclined to the latter 
view, although I think much careful observation is still re- 
quired to substantiate it ; and some even of our own observa- 
tions would seem to tell somewhat in the opposite direction. 
Although Orbulina and Globigerina are very usually asso- 
ciated, in different localities, they are so in different propor- 
tions ; and in the icy sea to the south of Kerguelen, although 
Globigerina was constantly taken in the surface-net, not a 
single Orbulina was detected. Like Globigerina, Orbulina 
is most fully developed and most abundant in the warmer 
seas.— WYVILLE THomson, loc. cit. 
Coccoliths and Rhabdoliths.—Over a very large part of the 
“* Globigerina ooze” area, and especially in those intertropical 
regions in which the formation is most characteristically 
developed, although the great bulk of the ooze is made up of 
entire shells and fragments of shells of the above-described 
foraminifera, besides these there is frequently a considerable 
proportion (amounting in some cases to about twenty per 
cent.) of fine granular matter, which fills the shells and the 
interstices between them, and forms a kind of matrix or 
cement. This granular substance is, like the shells, calca- 
reous, disappearing in weak acid to a small insoluble residue: 
with a low microscopic power it appears amorphous, and it 
is likely to be regarded at first sight as a paste made up of 
the ultimate calcareous particles of the disintegrated shells, 
but under a higher power it is found to consist almost 
entirely of “ coccoliths”’ and “ rhabdoliths.” I need scarcely 
enter here into a detailed description of these singular bodies, 
which have already been carefully studied by Huxley, Sorby, 
Gimbel, Carter, Oscar Schmidt, Wallich, and others. I 
need only state that I believe our observations have placed it 
beyond a doubt that the ‘‘ coccoliths” are the separated ele- 
ments of a peculiar calcareous armature which covers certain 
spherical bodies (the “ coccospheres”’ of Dr. Wallich). The 
rhabdoliths are the like elements of the armature of extremely 
beautiful little bodies, which have been first observed by Mr. 
Murray, and naturally called by him “rhabdospheres. Coc- 
