CHAP. III. ] TENERIFFE TO SOMBRERO. 99 
longing to certain well-defined families, complete the fauna of 
the region. Next we have a layer an inch or two in thickness, 
somewhat more firm in consistence, in which most of the shells 
of all kinds are more or less broken up, and their fragments 
cemented together by a calcareous paste, the result of the com- 
plete disintegration of many of them; and beneath this a near- 
ly uniform calcareous paste, colored gray by decomposed or- 
ganic matter, and containing whole and fragmentary shells only 
sparsely scattered through it. Excellent samples, showing the 
gradual passage from one condition into the other, are often 
brought up in the tube of the sounding-machine. 
Since the time of our departure, Mr. Murray has been paying 
the closest attention to the question of the origin of this calea- 
reous formation, which is of so great interest and importance 
on account of its anomalous character and its enormous exten- 
sion. Very early in the voyage, he formed the opinion that all 
the organisms entering into its composition at the bottom are 
dead, and that all of them live abundantly at the surface and 
at intermediate depths, over the globigerina-ooze area, the ooze 
being formed by the subsiding of these shells to the bottom 
after death. 
This is by no means a new view. It was advocated by the 
late Professor Bailey, of West Point, shortly after the discoy- 
ery, by means of Lieutenant Brooke’s ingenious sounding- in- 
strument, that such a formation had a wide extension in the 
Atlantic. Johannes Miller, Count Pourtales, Krohn, and Max 
Schultze observed Globigerina and Orbulina living on the sur- 
face; and Ernst Haeckel, in his important work upon the Radi- 
olaria, remarks “that we often find upon, and carried along by, 
the floating pieces of sea-weed which are so frequently met 
with in all seas, foraminifera as well as other animal forms 
which habitually live at the bottom. However, setting aside 
these accidental instances, certain foraminifera, particularly in 
their younger stages, occur in some localities so constantly, and 
