THE SILURIAN BEACH. 
39 
which shows a complete independence of exter- 
nal influences. 
Take, for instance, the similarity above alluded 
to between the faunae of the Arctics and that of 
the Alps, certainly showing a direct relation be- 
tween climatic conditions and animal and vege- 
table life. Yet even there, where the shades of 
specific difference between many animals and 
plants of the same class are so slight as to baffle 
the keenest investigators, we have representative 
types both in the Animal and Vegetable King- 
doms as distinct and peculiar as those of widely 
removed and strongly contrasted climatic condi- 
tions. Shall we attribute the similarities and 
the differences alike to physical causes ? Com- 
pare, for example, the Reindeer of the Arctics 
with the Ibex and the Chamois, representing the 
same group in the Alps. Even on mountain- 
heights of similar altitudes, where not only cli- 
mate, but other physical conditions would sug- 
gest a recurrence of identical animals, we do not 
find the same, but representative types. The 
Ibex of the Alps differs, for instance, from that 
of the Pyrenees, that of the Pyrenees from those 
of the Caucasus and Himalayas, these again from 
each other and from that of the Altai. 
But perhaps the most conclusive proof that we 
must seek for the origin of organic life outside 
of physical causes consists in the permanence of 
