204 THE ATLANTIC. [cHAP. 1m. 
care following its spreading or contracting movements. At 
the same time an infinitely delicate sheath of sarcode contain- 
ing minute transparent granules, but no oil-globules, rises on 
each of the spines to its extremity, and may be seen creeping 
up one side and down the other of the spine with the peculiar 
Jlowing movement with which we are so familiar in the pseu- 
dopodia of Gromia and of the Radiolarians. If the cell in 
which the Globigerina is floating receive a sudden shock, or if 
a drop of some irritating fluid be added to the water, the whole 
mass of sarcode retreats into the shell with great rapidity, draw- 
ing the oil-globules along with it, and the outline of the sur- 
face of the shell and of the hair-like spines is left as sharp as 
before the exodus of the sarcode. 
Major Owen (op. cit.) has referred the Globigerina with spines 
to a distinct species, under the name of G. hirsuta. I am in- 
clined rather to helieve that all Globigerine are, to a greater or 
less degree, spiny when the shell has attained its full develop- 
ment. In specimens taken with the tow-net the spines are very 
usually absent ; but that is probably on account of their extreme 
tenuity; they are broken off by the slightest touch. In fresh 
examples from the surface, the dots indicating the origin of the 
lost spines may almost always be made out with a high power. 
There never are spines on the Globigerinew from the bottom, 
even in the shallowest water. Two or three very marked vari- 
eties of Globigerina occur; but I certainly do not think that 
the characters of any of them can be regarded as of specific 
value. 
There is still a good deal of obscurity about the nature of 
Orbulina universa, an organism which occurs in some places in 
large proportion in the globigerina ooze. The shell of Orbu- 
lina (Fig. 47) is spherical, usually about *5 mm. in diameter, but 
it is found of all smaller sizes. The texture of the mature 
shell resembles closely that of Globigerima, but it differs in 
some important particulars. The pores are markedly of two 
