396 LIFE AT GREAT DEPTHS. 
It is not a matter for surprise, then, that there being such a — 
thing as persistence of type and of species, some very old forms — 
should have lived on through the ages, whilst their surroundings 
were changed over and over again. But this persistence does not — 
indicate that there have not been sufficient physical and biolog- — 
ical changes during its lasting to alter the face of all things enough 
to give geologists the right of asserting the succession of several : 
periods. The occurrence of early Cainozoic Madreporaria in the — 
deep sea to the northwest of Great Britain only proves that cer- 
tain forms of life have persisted during the vast changes in the 3 
physical geography of the world which were initiated by the up- 
heaval of the Alps, the Himglayas, and large masses of the Andes. 
To say that we are, therefore, still in the Cainozoic or Cretaceous 
age would hardly be consistent with the necessary termine ME 
geological science. 
During the end of the Miocene age and the whole of the Pliocene; 
the Sicilian area was occupied by a deep sea, The distinction be 
tween the faunas of those times and the present becomes less, : 
year after year, as science progresses; and it is evident that & 
great number of existing species of nearly every class flourished 
before the occurrence of the great changes in physical geology 
which have become the artificial breaks of tertiary geologists. 
That the Cainozoic deep-sea corals should resemble, and in some 
instances should be identical in species with, the forms now in- 
habiting vast depths, is therefore quite in accordance with the 
philosophy of modern geology. Before the deposition of the Cain- 
ozoic strata, and whilst the deep-sea deposits of the Eocene age 
were collecting. in the Franco-British area, there was a 
rarian fauna there, which was singularly like unto that which fol 
lowed it, both as regards the shape of the forms and their gi 
Still earlier, during the slow subsidence of the great Upper Cre- 
taceous deep-sea area there was a coral fauna in the north and 
west of Europe, of which the existing is very representative. Te i 
is replaced in the present state of things by a branching 
lia. The similarity of deep-sea coral faunas might be carried st 
further back in the world’s history ; but it must be enough for ny 
purpose to assert the representative character and the ho 
of thé Upper Cretaceous, the Tertiary, and the existing deep-sea 
