206 THE ATLANTIC. [cHapP. III. 
Orbulina than they are in Globigerina ; and the spines, which 
are of great length and extreme tenuity, seem rather to arise 
abruptly from the top of scattered papille than to mark the in- 
tersections of the crests. This origin of the spines from the 
papille can be well seen with a moderate power on the periph- 
ery of the sphere. The spines are hollow and flexible: they 
naturally radiate regularly from the direction of the centre of 
the sphere; but even in specimens which have been placed un- 
der the microscope with the greatest care, they are usually en- 
tangled together in twisted bundles. They are so fragile that 
the weight of the shell itself, rolling about with the motion of 
the ship, is usually sufficient to break off the whole of the 
spines, and leave only the papille projecting from its surface, 
in the course of a few minutes. In some examples, either those 
in process of development, or a series showing a varietal diver- 
gence from the ordinary type, the shell is very thin and almost 
perfectly smooth, with neither papillee nor spines, nor any visible 
structure except the two classes of pores, which are constant. 
The chamber of Orbulina is often almost empty; even in 
the case of examples from the surface which appear, from the 
freshness and transparency of the shell, to be living, it is never 
full of sarcode; but it frequently contains a small quantity of 
yellow sarcode stuck against one side, as in the last chamber of 
Globigerina. Sometimes, but by no means constantly, within 
the chamber of Orbulina there is a little chain of three or four 
small chambers singularly resembling in form, in proportion, 
and in sculpture, a small Globigerina; and sometimes, but 
again by no means constantly, spines are developed on the sur- 
face of the calcareous walls of these inner chambers, like those 
on the test of Globigerina. The spines radiate from the posi- 
tion of the centre of the chambers and abut against the inside 
of the wall of the Orbulina. In a few cases, the inner cham- 
bers have been observed apparently arising within or amidst 
the sarcode adhering to the wall of the Orbulina. 
