22 NATURAL SCIENCE [JuLy 
instance, Pullenia obliquiloculata and Globigerina aequilateralis ; on 
the other hand, Pulvinulina menardii and Globigerina rubra appear 
to be more abundant in the tropical Atlantic. 
The species inhabiting the north and south temperate regions, 
and the species inhabiting the two polar regions, appear to be 
nearly if not quite identical. 
The distribution of the dead shells of the pelagic Foraminifera 
on the floor of the ocean corresponds exactly with the distribution 
of the living specimens at the surface of the sea. It has sometimes 
been urged that the dead shells of tropical species might be carried 
a long way to the north or to the south by oceanic currents, but 
this does not seem in any way to be the case; the distribution of 
the dead shells on the bottom does not appear to be much if any 
Fic, 3.—Cymbalopora (Tretonyphalus) bulloides (d’Orbigny). «a, large surface specimen ; 
b, small (young) specimens from the same gathering ; c, distal face of the 
balloon-like chamber, showing the entosolenian orifice, seated in a slight 
depression. All magnified 60 diam. 
wider than that of the living specimens at the surface, and this 
shows that the dead shells must reach the bottom a very short time 
after the death of the organisms, The fact that the distribution of 
these shells at the bottom of the ocean is governed by the surface 
conditions is of itself almost conclusive proof that they live only at 
the surface, for otherwise their distribution would be similar to 
that of bottom-living, or benthos, species, which is wholly inde- 
pendent of the temperature conditions prevailing at the surface of 
the sea. Carpenter! and Brady? at one time held the view that 
young individuals lived at the surface and adult ones at the bottom ; 
in addition to the fact that no living specimen has ever been obtained 
from the bottom, the above considerations with regard to distribu- 
tion show that this view is not supported by any trustworthy obser- 
vations. In the surface gatherings the young individuals are much 
1 Op. cit. 2 Op. cit. 
