216 
PA RT, de 
FOSSIL ZOOLOGY. 
‘‘ THE very ground on which we tread, and the mountains that 
surround us, are vast tumuli in which the Organic Remains of a 
Former World are enshrined.” —PARKINSON. 
THE existing species of animals scientifically determined 
by naturalists amount to upwards of one hundred thousand, 
while those known in a fossil state scarcely exceed twenty- 
five thousand ; yet the latter comprise examples of all the 
classes, and most of the families and genera, which still in- 
habit our planet. Although our notice of these remains must 
necessarily be very general, we shall endeavour to describe 
all that are of peculiar interest, either in a geological or 
zoological point of view; or which from their prevalence, 
or wide distribution, will frequently be met with by the col- 
lector in the course of his researches. 
Our examination will commence with animal organisms of 
the simplest structure, and proceed in an ascending order, 
in accordance with the usual zoological classifications ; but, 
as in the botanical department, it will be convenient occa- 
sionally to include the consideration of the fossil remains of 
more than one family in the same section, when associated 
in a particular locality or deposit. 
In the preliminary remarks on the nature of Organic 
Remains (ante, p. 43), the various conditions in which the 
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