New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1881-02-01


fam;l;ar and nermanent Outline of masses OF land
and water we have TO deal with vast tracts or
snaces occupied by animals. Each kind has It's
territory or area OF distribution These vary ID
extent according to the groups defined. "opecinc
areas" are those occupied by any gwen species
Every species has al OF distribution 10 WHICH
within certain limits of fuctuation it is perina-
nenty confined but while some OF these areas are
very extensive, others are remarkably restrlrtco'
1t might be expected that birds. considering thcr
mowers of flight would be the freest in their ranges
but it is u curious fact that some OF them illustrate
the EXTREMIST restriction The beautiful sun-brd.
peculiar starting, is almost or quite connod 10 inc
warmer portions of the valley of tho Jordan; ana
several species of laughing thrusles are to bo found
only on the SUBMITS OF the llmalayas. The hum
ming birds of tropical America furnish striking ex-
ampes of restricted habitats. The great volcanic
peaks of Chlmborazo and Pichincha have eacn
peculiar species of humming-brd c0nlneu 10 oel'
lust below the limits of perpetual SNOW "hic 'no
extinct volcano of ChiriquI has species cohhheu
to its wooded crater. On the other hand, many
species of birds are very widely distributed Inc
little northern willOw-wren ranges from Norway
across Asia to Alaska and southwark to CeYlon'
China, Borneo, and TimOr. The hshing-haWK ana
barn-Ow are also very extensively distributed; lAo
wolf ranges over great area, though some question
separated ocalities but among the undisputcd
species of mammalia the leopard inhabts an enor-
nous range and is probably the most extensively
distributed of any known mammal. But very wide
and very narrow ranges exceptional. lie great
majority of species both of mammals ana Dlrds
ranging only over moderately wide areas.
As genera consist of clOscly-allled groups OF
| species the generic areas differ widely from the
specific areas and are of course more extensive
| Tho number of species i'll a genus varies greatly
from one up to several hundreds. The giraffe the
secretary bird ard many Others have no close allies
and each forms genus by itself. The deer-genns
has forty Species the mouse and rat genus more
than a hundred species, there are more than 4oo
species of swallow tail butterflies. while among the
shells the genus helix. including the comlnonest
snail numbers 1000 described species and ranges
all over the world. AS pass to families and
orders new systems of distribution arise, and we
here find few cases of restriction and many OF
world wide distribution. Tho distribution OF faml-
lies and orders gives rise to other and still more OK
tensyc areas. The matter is further complicated
bv oyerlaps and breaks in the areas OF distribution
The species of genus either occupy distinct areas
which arc sometimes widely separated, or they
touch and oycrlay each other. Tho best example
of separated but cOntermnOuS ranges is that OF the
beautiful South American wadlng-birds called
truinpcters There are five species all found IN the
Amazon Valley, but each limited to well-marked
district bounded by large , vcrs. Overlapping
areas are however the most common. Examples
of diScontnuous areas are often rcinarkablc. Inc
genus of blue magplcs has two species which are
scparated from each Othcr by 5000 miles OF con-
tinuous land. The same break of continuity is
often seen IN the distribution Of a single species.
OF the variable hare IT is said that there is gap of
about 600 miles between Its southern limits III
Russia and its temperance in the Alps
Tho new geography has still further complica-
tions The great natural divisions of the globe now
| serve only as landmarks for the construction OF
grand ideal divisions known as geological regions
The term Europe" for example. VIII NOT give
with any apprOac 10 accuracy, the range oil any one
genus of mammals or birds or perhaps not mat OF
half dozen species. Either they range into Siberia
| Asia Minor Palestine, or North Africa ar. wal,
lace takes the British mammals and land-blrdS and
follows them the W hole area they hllablt as an
example of geological region. Others nave orrh
traIi.'n re e", and the Oriental region
| We have illustrated these views OF Distribution
with same detail. Though they form hut inc Htarihg
| uoint of Mr. Walaccs discussion. But III no other
| way can get so clear conception oi inc btduth
of his task All these manifold complications Ill tho
| DISPERSION of animal lite over tho globe arr re-
uuircd be- accounted fOr II is needless to say that
fine authors treatment OF the subject Is based IN
tircly upon the doctrine OF evolution. Ihc ionith
cIaItcr OF his work ~ entitled: e tFolutlol me
KEY 80 distribution" AMI II contains an ainIfahic
summary of the chief points OF the doctrine. Mr.
Wallace here speaks WIN the authority "i IN
original discOveier and In" skill of practical "N-
poslt0r. He shows that evolution - the ohl' prl
cpe that is adequately appllfable 10 the snhrcl'
and that the law OF descent with variation acting
through vast periods and influenced by changes OF
climate IN geological times Is already competent to
| explain the main features III the distribution OF
terrestrial life. In facr. the law OF evolution I'M
niles and compeS the great results when we now
| observe. Upon this point the author remarks;
When writing the su ject ~ DIS riun"n, II Usually
seems been fOrg tton ha' tIc theory OF rvCu'
ton absolutely necessities the former "ts'enct Oh
| whole series OF cxtinc. genera Hing up the gaps De-
| tween the isolated genera which III may eases now
alone exists while II 10 almost an axiom OF urhl Sc
lection" that such numerous forms or one type ccd
| only have been developed IN vide area and under
| varied conditions, lmniying great lapse OF time In
our succeeding chapters We suai sho" NAV we kuoWn
and probable changes OF sea and lahl the known
the different gronps Of animals such ~ would have
| enabled all tue disconnected groups To have once
for Iued paris OF continuous serrs frnolS OF Nurh
former continuity are oinuay being oDaned by the
discovery allied extinct forms In Veirg Hh-, mt
the extreme mperfecti0n Of he illogical record an re-
CARDS land animals, renders 1t unlikely thut ths PROOF
viii be Forthcoming in the majority Of cases Tie NJ"
| w,uli certainly be found Is II superstition which, not
| withstandng the efforts Of Iycil and DARWIN, sti
largely prevails among untnrats, In; ANTI II Is got rid
o. of the former distribution OF life upon
| the earth h" att1Iucd
| Mr. Wallace next passes in series OF chapters to
the recOntc changes involved in the distribution
| of organisms. He first investigates the means ny
which the various groups OF animals are enabled TO
overcome the natural barriers by which they are
restricted. Chapter ", on :" The powers OF DIS
| persal of animals and plants" points out the mum
| herless curious ways in which the various classes
of animals and plants arc enabled to extend their
| areas In Chapter W., he inquiries how far those
barriers are thensclyr liable TO be altered or aho
| lscd and what are the exact nature ana amount Of
/ the changes of sea and land which our earth has
| undergone IN past times. The geographical and
geological changes in past periods are here traced
ont and the question Of the pcrmancIlce OF contl-
| nents is considered. This is regarded as funda-
| mental question, but it is still III controversy: MI
| Wallare adduccs several distinct clasNcs Ui evl
| 1,u IN hes grand
| the position Of the great oceans and the chIc1
| land arcas-have remained on the whole unchanged
| throughout geological time. The general stanhitY
| of continents has however, been accompanied by
| constant changes of form, ma insuar conditions