THE INTRODUCTION OF NEW SPECIES, 25 
of them, had we a view of all the forms which have 
ceased to live. The great gaps that exist between 
fishes, reptiles, birds, and mammals would then, no 
doubt, be softened down by intermediate groups, and 
the whole organic world would be seen to be an 
unbroken -and harmonious system 
Conclusion. 
It has now veen shown, though most briefly and 
imperfectly, how the law that “Every species has come 
into existence coincident both in time and space with a 
pre-existing closely allied ‘species,’ connects together 
and renders intelligible a vast number of independent 
and hitherto unexplained facts. The natural system 
of arrangement of organic beings, their geographical 
distribution, their geological sequence, the phenomena 
of representative and substituted groups in all their 
modifications, and the most singular peculiarities of 
anatomical structure, are all explained and illus- 
trated by it, in perfect accordance with the vast 
mass of facts which the researches of modern na- 
turalists have brought together, and, it is believed, 
not materially opposed to any of them. It also 
claims a superiority over previous hypotheses, on 
the ground that it not merely explains, but necessi- 
tates what exists. Granted the law, and many of 
the most important facts in Nature could not have 
been otherwise, but are almost as necessary deduc- 
tions from it, as are the elliptic orbits of the planets 
from the law of gravitation. 
