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BOOK  V. 
PALHONTOLOGICAL GEOLOGY. 
PALHONTOLOGY treats of the structure, affinities, classification, and 
distribution in time of the forms of plant and animal life imbedded 
in the rocks of the earth’s crust. Considered from the biological 
side it is a part of zoology and botany. A proper knowledge of extinct 
organisms can only be attained by the study of living forms, while 
our acquaintance with the history and structure of modern organisms 
is amplified by the investigation of their extinct progenitors. Viewed, 
on the other hand, from the physical side, paleontology is a branch 
of geology. Itis mainly in this latter aspect that it will here be 
discussed. 
Paleontology or Paleontological geology deals with fossils or 
organic remains preserved in natural deposits, and endeavours to 
gather from them information as to the history of the globe and its 
inhabitants. The term fossil, meaning literally anything “dug up,” 
was formerly applied indiscriminately to any mineral substance- 
taken out of the earth’s crust, whether organized or not. Ordinary 
minerals and rocks were thus included as fossils. For many years, 
however, the meaning of the word has been so restricted as to 
. inelude only the remains or traces of plants and animals preserved in 
any natural formation, whether hard rock or loose superficial deposit. 
The idea of antiquity or relative date is not necessarily involved in 
this conception of the term. ‘Thus the bones of asheep buried under 
eravel and silt by a modern flood, and the obscure crystalline 
traces of a coral in ancient masses of limestone, are equally fossils, 
Nor has the term fossil any limitation as to organic grade. It 
includes not merely the remains of organisms, but also whatever was 
directly connected with or produced by these organisms. Thus 
the resin which was exuded from trees of long-perished forests 
is as much a fossil as any portion of the stem, leaves, flowers, or 
fruit, and in some respects is even more valuable to the geologist 
than more determinable remains of its parent trees, because it has 
often preserved in admirable perfection the insects which flitted 
about in the woodlands. The burrows and trails of a worm preserved 
in sandstone and shale claim recognition as fossils, and indeed are 
commonly the only indications to be met with of the existence of 
annelide life among old geological formations. The droppings 
