Omaha daily bee., 1915-07-25

genus originated. How did these genera
or their successors disperse? II they
could not ny or were not transported,
then he insists. they must have dispersed
by means of existing land bridges and
occasionally by natural marine grass
RATS.
The distance between Farce Islands
and Scotland and between tho latter and
western Norway is 240 miles In each
case The water depths existing between
them to-day and in the other spaces was
caused, geologists assert, by the weight
Of successive Zee caps, depressing the
earth crust. Some geologists figure as
many as six successive ice caps The
number has little bearing on the matter
since the last one was sufficiently appall-
ing TO make Off perfect navigation at tho
present time, where walking had former
ly been good. l say appalling because
there Is no doubt that the last ice cap,
still receding, northward, pounded the
earth crust down to stay where Il is,
while the first ice caps did no such stunt
One or several times. II In assumed, the
earth arose several hundred or more feet
after the first ice cap receded.
Archibald Geikie accumulated a lot Of
data on the subject which remains in his
still authoritative work on "The Great
Ice Age" So, the geologists data is used
by paleontologists to support hypotheti-
cal land bridges In order to account for
migrations OF men, other mammals,
hightless birds, reptiles, crustaceans, in.
vertebrates, trees, and plants which had
seeds too heavy to be borne by winds and
which sank in water rather than swim
for It.
Just how invertebrates migrate long
distances is a matter which II is to be
hoped Professor lngen or others will
clear up. / have seen clans travel by
suction, but only on the bottom of water
areas. Stejneger sets up such Atalantic
and Arctalantic biota as world girdlers
on the land bridges. but without doscrib-
ing the process. Among these he men,
tions terrestrial molhscs, earthworms,
isopod crustaceans, noctuid moths, bum.
BILE bees and an entire series OF insects
OF the orders OF lepidoptera, hemiptera
and coleoptera.
Some of these are essentially slow
travellers and probably required hun.
dreds, perhaps thousands OF years to dis
perse the tremendous distances across
those land bridges and over the noun
tains and plains OF the mainlands. Give
pair of snails several millions OF years
and they and their descendants could no
uouDJ populate the entire earth with their
Kind, however slow cartoonist might de.
pict them
Among the mammals common 10 the
whole sectional circle are the variable
hare, the lemming. the red-backed Hel6
mouse, the wild reindeer, the red deer.
very primitive horses and the extinct
mammoth.
When one considers the several types
OF men, other animals end plants that
have apparently endured continuously
since early Pleistocene times, and some
OF them much longer. in the cold storage
section cf the world, there cannot be the
slightest doubt that II land bridges ex.
listed. there was ample travelling done
over them In both directions. The
Princeton expedition will at least have
the satisfaction hat all OF the evidence
collected supports the hypothesis of a
LabradorScotlan1 land bridge. Even q
Missourian cannot deny that 1t may nave
been.