There can now be no doubt, therefore, that Globigerinoe live at the top of the sea; but the question may still be raised whether they do not also live at the bottom.  In favour of this view, it has been urged that the shells of the Globigerinoe of the surface never possess such thick walls as those which are fouled at the bottom, but I confess that I doubt the accuracy of this statement.  Again, the occurrence of minute Globigerinoe in all stages of development, at the greatest depths, is brought forward as evidence that they live in situ.  But considering the extent to which the surface organisms are devoured, without discrimination of young and old, by Salpoe and the like, it is not wonderful that shells of all ages should be among the rejectamenta.  Nor can the presence of the soft parts of the body in the shells which form the Globigerina ooze, and the fact, if it be one, that animals living at the bottom use them as food, be considered as conclusive evidence that the Globigerinoe live at the bottom.  Such as die at the surface, and even many of those which are swallowed by other animals, may retain much of their protoplasmic matter when they reach the depths at which the temperature sinks to 34 deg. or 32 deg.  Fahrenheit, where decomposition must become exceedingly slow.

Another consideration appears to me to be in favour of the view that the Globigerinoe and their allies are essentially surface animals.  This is the fact brought out by the Challenger’s work, that they have a southern limit of distribution, which can hardly depend upon anything but the temperature of the surface water.  And it is to be remarked that this southern limit occurs at a lower latitude in the Antarctic seas than it does in the North Atlantic.  According to Dr. Wallich ("The North Atlantic Sea Bed,” p. 157) Globigerina is the prevailing form in the deposits between the Faroe Islands and Iceland, and between Iceland and East Greenland—­or, in other words, in a region of the sea-bottom which lies altogether north of the parallel of 60 deg.  N.; while in the southern seas, the Globigerinoe become dwarfed and almost disappear between 50 deg. and 55 deg.  S. On the other hand, in the sea of Kamschatka, the Globigerinoe have vanished in 56 deg.  N., so that the persistence of the Globigerina ooze in high latitudes, in the North Atlantic, would seem to depend on the northward curve of the isothermals peculiar to this region; and it is difficult to understand how the formation of Globigerina ooze can be affected by this climatal peculiarity unless it be effected by surface animals.