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Ti'ic TIMOTHY I loPKtNa-seqw
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ISLAND LIFE
OR, THE PHENOMENA AND CAUSES OF
INSULAR FAUNAS AND FLORAS
XNCLCDIXO
A REVISION AND ATTEMPTED SOLUTION OP THE PROBLEM OP
GEOLOGICAL CLIMATES
BY
ALFRED RUSSEL WALLACE
AUTHOR or **THK GEOGRAPHICAL DISTRIBmOS OF AKIMALS"
*'THS MALAY ARCHIPELAGO** XTC.
NEW YORK
HARPER k BROTHERS, FRANKLIN SQUARE
1881
WIS
249253
• •
• •
e k •
9
TO
SIR JOSEPH DALTON HOOKER
K«C<8tIt| C«B«| <.n*8<| £TC«| ETC*
WHO, MORE THAN ANT OTHER WRITER, HAS ADVANCED OUR KNOWLEDGE
OF THE GEOGRAPHICAL DISTRIBL-TION OF PLANTS, AND
ESPECTALLY OF INSULAR FLORAS
3 DtVxcatt tl]i0 Uolttme
ON A KINDRED SUBJECT, AS A TOKEN OF
ADMIRATION AND REGARD
PREFACE.
The present volume is the result of four years' additional
thought and research on the lines laid down in my " Geograph-
ical Distribution of Animals," and may bo considered as a pop-
ular supplement to and completion of that work.
It is, however, at the same time, a complete work in itself ;
and, from the mode of treatment adopted, it will, I hope, be
well calculated to bring before the intelligent reader the wide
scope and varied interest of this branch of natural history. Al-
though some of the earlier chapters deal with the same ques-
tions as my former volumes, they are here treated from a dif-
ferent point of view ; and, as the discussion of them is more
elementary and at the same time tolerably full, it is hoped that
they will prove both instructive and interesting. The plan of
my larger work required that genera only should be taken ac-
count of ; in the present volume I often discuss the distribution
of species^ and this will help to render the work more intelligi-
ble to the unscientific reader.
The full statement of the scope and object of the present
essay given in the " Introductory " chapter, together with the
" Summary " of the whole work and the general view of the
more important arguments given in the " Conclusion," render it
unnecessary for me to oflfer any further remarks on these points.
I may, however, state generally that, so far as I am able to
vi PREFACE.
jadge, a real advance has here been made in the mode of treat-
ing problems in geographical distribution, owing to the firm
establishment of a number of preliminary doctrines or " prin-
ciples," which in many cases lead to a far simpler and yet more
complete solution of such problems than has been hitherto pos-
sible. The most important of these doctrines are those which es-
tablish and define — (1) The former wide extension of all groups
now discontinuous, as being a necessary result of " evolution ;"
(2) The permanence of the great features of the distribution of
land and water on the earth's surface ; and (3) The nature and
frequency of climatal changes throughout geological time.
I have now only to thank the many friends and correspond-
ents who have given me information or advice. Besides those
whose assistance is acknowledged in the body of the work, I
am especially indebted to four gentlemen who have been kind
enough to read over the proofs of chapters dealing with ques-
tions on which they have special knowledge, giving me the ben-
efit of valuable emendations and suggestions. Mr. Edward R.
Alston has looked over those parts of the earlier chapters which
relate to the mammals of Europe and the north temperate
zone ; Mr, S. B. J. Skertchley, of the Geological Survey, has
read the chapters which discuss the glacial epoch and other ge-
ological questions ; Professor A. Xcwton has looked over the
passages referring to the birds of the Madagascar group ; while
Sir Joseph D. Hooker has given me the invaluable benefit of
hia remarks on my two chapters dealing with the New Zealand
flora.
CONTENTS.
PAET I.
THE DISPERSAL OP ORGANISMS : ITS PHENOMENA, LAWS,
AND CAUSES.
CHAPTER L
INTRODUCTORY.
RemarkAble Contrasts in Distribation of Animals. — Britain and Japan. — Australia
and New Zealand. — Bali and Lombok. — Florida and Bahama Islands. — Brazil
and Africa. -^Borneo, Madagascar, and Celebes. — Problems in Distribation to be
Fonnd in every Country. — Can be Solved only by the Combination of many Dis-
tinct Lines of Inquiry, Biological and Physical. — Islands Offer the Best Subjects
for the Study of Distribution. — Outline of the Subjects to be Discussed in the
Present Volume Pages 3-11
CHAPTER II.
THE ELEMENTARY FACTS OF DISTRIBUTION.
Importance of Locality as an Essential Character of Species. — Areas of Distribution.
— ExtenLand Limitations of Specific Areas. — Specific Range of Birds. — Generic
Areas. — Separate and Overlapping Areas. — The Species of Tits as Illustrating
Areas of Distribation. — The Distribution of the Species of Jays. — Discontinuous
Generic Areas. — Peculiarities of Generic and Family Distribution.^General Feat-
ures of Overlapping and Discontinuous Areas. — Restricted Areas of Families. —
The Distribation of Orders. 12-29
CHAPTER in.
CLASSIFICATION OF .THE FACTS OF DISTRIBUTION. — ZOOLOGICAL REGIONS.
The Greographical Divisions of the Globe do not Correspond to Zoological Divisions.
— The Range of British Mammals as Indicating a Zoological Region. — Range of
East Asian and North African Mammals. — The Range of British Birds. — Range
of East Asian Birds. — The Limits of the Palsearctic Region. — Characteristic Feat-
ures of the PaloMirctic Region. — Definition and Characteristic Groups of the Ethi-
opian Region.^Of the Oriental Region.— Of the Australian Region. — Of the Ne-
arctic Region. — Of the Neotropical Region. — Comparison of Zoological Regions
with the Geographical Divisions of the Globe 30-52
viii CONTENl^.
CHAPTER IV.
EVOLUTION AS THE KE7 TO DISTRIBUTION.
Importance of the Doctrine of Evolution. — The Origin of New Species. — Variation
in Animals. — The Amount of Variation in North American Birds. — How New Spe-
cies Arise from a Variable Species. — Definition and Origin of Genera. — Cause of
the Extinction of Species. — The Rise and Decay of Species and Genera. — Discon-
tinuous Specific Areas, why IIslyq. — Discontinuity of the Area of Partis palustria.
— Discontinuity of Emberlza schanicius, — The European and Japanese Jays. —
Supposed Examples of Discontinuity among North American Birds. — Distribution
and Antiquity of Families. — Discontinuity a Proof of Antiquity. — Concluding
Kemarks Pages 63-67
CHAPTER V.
THE POWERS OF DISPERSAL OF ANIMALS AND PLANTS.
Statement of the General Question of Dispersal. — The Ocean as a Barrier to the
Dispersal of Mammals. — The Dispersal of Birds. — The Dispersal of Reptiles.
— The Dispei*Siil of Insects. — The Dispersal of Land Molhisca. — Great An-
tiquity of Land Shells. — Causes Favoring the Abundance of Land Shells.— The
Dispersal of Plants. — Special Adaptability of Seeds for Dispei'siil. — Birds as
Agents in the Dispersal of Seeds. — Ocean Currents as Agents in Plant-dispersal.
— Dispersal along Mountain-chaius. — Antiquity of Plants as Affecting their Dis-
tribution C8-78
CHAPTER VI.
GEOGRAPHICAL AND GEOLOGICAL CHANGES : THE PERMANENCE OF
CONTINENTS.
Changes of Land and Sea, their Nature and Extent. — Shore-deposits and Stratified
Koci^s. — The Movements of Continents. — Supposed Oceanic Formations; the
Origin of Chalk. — Fresh -water and Shore Deposits as Proving the Permanence of
Continents. — Oceanic Islands as Indications of the Permanence of Continents and
Oceans. — Geneml Stability of Continents with Constant Change of Form. — Effect
of Continental Changes on the Distribution of Animals. — Changed Distribution
Proved by the Extinct Animals of Different Epochs. — Summary of Evidence for
the General Permanence of Continents and Oceans 70-100
CHAPTER VII.
CHANGES OF CLIMATE WHICH HAVE INFLUENCED THE DISPERSAL OF
ORGANISMS : THE GLACIAL EPOCH.
Pi*oofs of the Recent Occurrence of a Glacial Epoch. — Moraines. — Travelled Blocks.
— Glacial Deposits of Scotland: the "Till." — Inferences from the Glacial Phe-
nomena of Scotland. — Glacial Phenomena of North America. — Effects of the Gla-
CONTENTS. ix
cial Epoch on Animal Life. — Warm and Cold Periods. — Palaeontological Evidence
of Alternate Cold and Warm Periods. — Evidence of Interglacial Wann Periods
on the Continent and in North America. — Migrations and Extinctions of Organ-
isms Caused by the Glacial Epoch Pages 101-118
CHAPTER VIIL
THE CAUSES OF GLACIAL EPOCHS.
Various Suggested Cause?. — Astronomical Causes of Changes of Climate. — Differ-
ence of Temperature Caused by Varying Distance of tiie Sun. — Properties of Air
and Water, Snow and Ice, in Relation to Climate. — Effects of Snow on Climate. —
High Land and Great Moisture Essential to the Initiation of a Glacial Epoch. —
Perpetual Snow nowhere Exists on Lowlands. — Conditions Determining the Pres-
ence or Absence of Perpetual Snow.— EflSciency of Astronomical Causes in Pro-
ducing Glaciation. — Action of Meteorological Causes in Intensifying Glaciation.
— Summary of Causes of Glaciation. — Eftect of Clouds and Fog in Cutting off* the
Sun's Heat. — South Temperate America as Illustrating the Influence of Astronomi-
cal Causes on Climate. — Geogmphical Changes, how far a Cause of Glaciation. —
Land Acting as a Barrier to Ocean Currents. — The Tiieory of Interglacial Periods
and their Probable Character.— Probable Effect of Winter in Aphelion on the Cli-
mate of Biitain. — Tiie Essential Piinciple of Climatal Change Restated. — Prob-
able Date of tlie Last Glacial Epoch. — Changes of the Sea-level Dependent on
Glaciation. — The Planet Mars as Bearing on the Theory of Eccentricity as a
Cause of Glacial Epochs 119-lCO
CHAPTER IX.
ANCIENT GLACIAL EPOCHS, AND MILD CLIMATES IN THE ARCTIC REGIONS.
Dr. CroU's Views on Ancient Ghicial Epochs. — Effects of Denudation in Destroying
the Evidence of Remote Ghicial Epochs. — Rise of Sea-level Connected with
Glacial Epochs a Cause of Further Denudation. — What Evidence of Early Glacial
Epochs may be Expected. — Evidences of Ice-action during the Tertiary Period.
— The Weight of the Negative Evidence. — Temperate Climates in the Arctic Re-
gions.— The Miocene Arctic Flora. — Mild Arctic Climates of the Cretaceous
Period. — Stratigrnphical Evidence of Long-continued Mild Arctic Conditions. —
The Causes of Mild Arctic Climates. — Geographical Conditions Favoring Mild
Northern Climates in Tertiary Times. — ^The Indian Ocean as a Source of Heat in
Tertiary Times. — Condition of North America during the Tertiary Period. —
Effect of High Eccentricity on Warm Polar Climates. — Evidences as to Climate
in the Secondary and Palaeozoic Epochs. — Warm Arctic Climates in Early Sec-
ondary and Palaeozoic Times. — Conclusions as to the Climates of Secondary and
Tertiary Periods. — General View of Geological Climates as Dependent on the
Physical Features of the Plarth*s Surface. — Estimate of the Comparative Effects
of Geographical and Physical Causes in Producing Changes of Climate.. lGl-199
X CONTENTS.
CHAPTER X.
THE EARTH^S AGE, AND THE RATE OF DEVELOPMENT OF ANIMALS AND
PLANTS.
Vaiioas Estimates of Geological Time. — Denudation and Deposition of Strata as a
Measm'e of Time. — How to Estimate the Thickness of the Sedimentary Rocks. —
How to Estimate the Average Kate of Deposition of the Sedimentary Rocks. —
The Rate of Geological Change probably Greater in very Remote Times. — ^Value of
the Preceding Estimate of Geological Time. — Organic Modification Dependent on
Change of Conditions. — Geographical Matations as a Motive Power in Bringing
about Organic Changes. — Climatal Revolutions as an Agent in Producing Organic
Changes. — Present Condition of the Earth one of Exceptional Stability as regards
Climate. — Date of Last Glacial Epoch, and its Bearing on the Measurement of
Geological Time. — Concluding Remarks. Pages 200-226
PAKT II.
INSULAR FAUNAS AND FLORAS.
CHAPTER XI.
THE CLASSIFICATION OF ISLANDS.
Importance of Islands in the Study of the Distribution of Organisms. — Classifica-
tion of Islands with Reference to Distribution. — Continental Islands. — Oceanic
Islands 229-233
CHAl^ER XII.
OCEANIC ISLANDS. — THE AZORES AND BERMUDA.
The Azores, or Western Islands. — Position and Physical Features. — Chief Zo-
ological Features of the Azores. — Birds. — Origin of the Azorean Bird Fauna. —
Insects of the Azores. — Land Shells of the Azores. — The Flora of the Azores. —
The Dispersal of Seeils. — Birds as Seed-camers. — Facilities for Dispersal of Azo-
rean Plants. — Important Deduction from the Peculiarities of the Azorean Fauna
and Flora 234-249
Bermuda. — Position and Physical Features. — The Red Clay of Bermuda. — Zoology
of Bermuda. — Birds of Bermuda.— Comparison of the Bird Faunas of Bermuda and
the Azores. — Insects of Bermuda. — Land MoUusca. — PMora of Bermuda. — Con-
cluding Remarks on the Azores and Bermuda 249-275
CHAPTER XIII.
THE GALAPAGOS ISLANDS.
Position and Physical Features. — Absence of Indigenous Mammalia and Ampliibia.
— Reptiles. — Bii-ds. — Insects and Land Shells. — ^The Keeling Islands as Illustrat-
CONTENTS. xi
ing the Manner in which Oceanic Islands are Peopled. — Flora of the Galapagos.
— Origin of the Flora of the Galapagos. — Concluding Remarks. . . .Pages 261-275
CHAPTER XIV.
ST. HELENA.
Position and Physical Features of St. Helena. — Change Effected by European Oc-
cupation.— The Insects of St. Helena. — Coleoptera. — Peculiarities and Origin of
the Coleoptera of St. Helena. — Land Shells of St. Helena. — Absence of Fresh-
water Organisms. — Native Vegetation of St. Helena. — The Relations of the Sr.
Helena Compositae. — Concluding Remarks on St. Helena 276-293
CHAPTER XV.
THE SANDWICH ISLANDS.
Position and Physical Features. — Zoology of the Sandwich Islands. — Birds. — Rep-
tiles.— Land Shells. — Insects. — Vegetation of the Sandwich Islands. — Peculiar
Features of the Hawaiian Flora. — Antiquity of the Hawaiian Fauna and Flora. —
Concluding Observations on the Fauna and Flora of the Sandwich Islands. — Gen-
eral Remarks on Oceanic Islands 203-SOG
CHAPTER XVI.
CONTINENTAL ISLANDS OF RECENT ORIGIN : GREAT BRITAIN.
Characteristic Features of Recent Continental Islands. — Recent Physical Changes
of the Britiiih Isles. — Proofs of Former Elevation. — Submerged Forests. — Buried
River Channels. — Time of Last Union with the Continent. — Why Britain is Poor
in Species. — Peculiar British Birds. — Fresh-water Fishes. — Cause of Great Spe-
ciality in Fishes. — Peculiar British Insects. — Lepidoptera Confined to the British
Isles. — Peculiarities of the Isle of Man Lepidoptera. — Coleoptera Confined to
the British Isles. — ^Trichoptera Peculiar to the British Isles. — Land and Fresh-
water Shells. — Peculiarities of the British Flora. — Peculiarities of the Irish Flora.
— Peculiar British Mosses and Hepaticae. — Concluding Remarks on the Peculiari-
ties of the British Fauna and Flora S07-341
CHAPTER XVn.
BORNEO AND JAVA.
Position and Physical Features of Borneo.— Zoological Features of Borneo: Mam-
malia.— Birds. — The AfiSnities of the Bomean Fauna.— Java, its Position and
Physical Features. — General Character of the Fauna of Java. — Differences be-
tween the Fauna of Java and that of the other Malay Islands. — Special Relations
of the Javan Fauna to that of the Asiatic Continent. — Past Geographical Ciianges
of Java and Borneo. — The Philippine Islands. — Concluding Remarks on the Malay
Iilandf 342-356
xii CONTENTS.
CHAPTER XVIII.
JAPAN AND FORMOSA.
Japan : its Position and Physical Features. — Zoological Features of Japan. — Mam-
malia.— Birds. — Birds Common to Great Britain and Japan. — Birds Pccnlior to
Japan. — Japan Birds Recnrring in Distant Areas. — Formosa. — Physical Features
of Formosa. — Animal Life of Formosa. — Mammalia. — Land Birds Peculiar to
Formosa.— Formosan Birds Kecuning in India or Molnya. — Comparison of
Faunas of Hainan, Formosa, and Japan. — General ICemarks on Recent Continen-
tal Islands. Pages 357-37r>
CHAPTER XIX.
ANCIENT CONTINENTAL ISLANDS I THE MADAGASCAR GROUP.
Remarks on Ancient Continental Islands. — Physical Features of Madagascar. — Bio-
logical Features of Madngasciir. — Mammalia. — Reptiles. — Rehition of Madagascar
to Africa. — Early History of Africa and Madagascar. — Anomalies of Distribution,
and how to Explain them. — The Birds of Madagascar as Indicating a Supposed
Lemurian Continent. — Submerged Islands between Madagascar and India. — Con-
cluding Remarks on '* Lemuria." — The Mascarene Islands. — The Comoro Islands.
— The Seychelles Archipelago. — Birds of the Seychelles. — Reptiles and Amphibia.
— Fresh -water Fishes. — Land Shells. — Mauritius, Bourbon, and Rodriguez. —
Birds. — Extinct Birds and their Probable Origin.— Reptiles. — Flora of Madagas-
car and the Mascarene Islands. — Curious Relations of Mascarene Plants. — En-
demic Genera of Mauritius and Seychelles. — Fragmentary Character of the Mas-
carene Flora. — Flora of Madagascar Allied to that of South Africa. — Preponder-
ance of Ferns in the Mascarene Flora. — Concluding Remarks on the Madagascar
Group 370-412
CnAPTER XX.
ANOMALOUS ISLANDS I CELEBES.
Anomalous Relations of Celebes. — Physical Features of the Island. — Zoological
Character of the Islands around Celebes. — The Malnvan and Australian Banks. —
Zoology of Celebes: Mammalia. — Probable Derivation of the Alainmals of Cele-
bes.— Birds of Celebes. — Bird-types Peculiar to Celebes. — Celebes not strictly a
Continental Island. — Peculiarities of the Insects of Celebes. — Himalayan Types of
Birds and Butterflies in Celebes. — Peculiarities of Shape and Color of Celebesian
Butterflies. — Concluding Remarks. — Appendix on the Birds of Celebes. . 413-433
CHAPTER XXI.
ANOMALOUS ISLANDS : NEW ZEALAND.
Position and Physical Features of New Zealand. — Zoological Character of New Zea-
land.— Mammalia. — Wingless Birds Living and Extinct. — Recent Existence of the
Moa. — Post Changes of New Zealand Deduced from its Wingless Birds. — Birds
CONTENTS. xiii
and Reptiles of New Zealand. — Conclusions from the Peculiarities of the New Zen-
land Fauna Pages 434-448
CHAPTER XXII.
THE FLORA OF NEW ZEALAND : ITS AFFINITIES AND PROBABLE ORIGIN.
Relations of the New Zealand Flora to that of Australia.— General Features of the
Australian Flora. — 'llie Floras of Southeastern and Southwestern Australia. — Geo-
logical Explanation of the Differences of these two Floras. — ^The Origin of the Aus-
tralian Element in the New Zealand Flora. — Tropical Character of the New Zea-
land Flora Explained. — Species Common to New Zealand and Australia mostly
Temperate Forms. — Why Easily Dispersed Plants have often Restricted Ranges. —
Summary and Conclusion on the New Zealand Flora 449-468
CHAPTER XXIIL
ON THE ARCTIC ELEMENT IN SOUTH TEMPERATE FLORAS.
European Species and Genera of Plants in the Southern Hemisphere. — Aggressive
Power of the Scandinavian Flora. — Means by which Plants have Migrated from
North to South. — Newly Moved Soil as Affording Temporary Stations to Migrat-
ing Plants. — Elevation and Depression of the Snow-line as Aiding the Migration
of Plants. — Changes of Climate Favorable to Migration. — The Migration from
North to South has been long going on. — Geological Changes as Aiding Migra-
tion.— Proofs of Migration by Way of the Andes. — ^Proofs of Migration by Way
of the Himalayas and Southern Asia. — Proofs of Migration by Way of the African
Highlands. — Supposed Connection of South Africa and Australia. — The Endemic
Genera of Plants in New Zealand. — The Absence of Southern Types from the
Northern Hemisphere. — Concluding Remarks on the New Zealand and South
Temperate Floras 4C9-489
CHAPTER XXIV.
SUMMARY AND CONCLUSION.
The Present Volume is the Development and Application of a Theory. — Statement
of the Biological and Physical Causes of Dispersal. — Investigation of the Facts of
Dispersal. — Of the Means of Dispersal. — Of Geographical Changes Affecting Dis-
persal.— Of Climatal Changes Affecting Dispersal. — The Glacial Epoch and its
Causes. — Alleged Ancient Glacial Epochs. — Warm Polar Climates and their Causes.
— Conclusions as to Geological Climates. — How far Different from those of Mr.
Croll. — Supposed Limitations of GreologicalTime. — Time Amply SuflScient both for
Geological and Biological Development. — Insular Faunas and Floras. — The North
Atlantic Islands. — The Galapagos. — St. Helena and the Sandwich Islands. — Great
Britain as a Recent Continental Island. — Borneo and Java. — Japan and Formosa.
— Madagascar as an Ancient Continental Island. — Celebes and New Zealand as
Anomalous Islands. — ^The Flora of New Zealand and its Origin. — ^The European
Element in the South Temperate Floras.— Concluding Remarks. 490-503
IKDBX 607-522
MAPS AND ILLUSTRATIONS.
PAOB
1. Map SnowiMO thb Distbidution of the True Jays Frontispiece.
2. Maf Showixo the Zoological Beoions To/ace 30
3. Map Showing the Distribution of Parvs Palustris, To face C2
4. A Glacier with Moraines (From Sir C. Lyell's " Principles of Ge-
ology"; 103
5. Map of the Ancient Rhone Glacier (From Sir C. Ljell's '* Autiquity
of Man") 105
C. Diagram Showing the Effects of Ecckntricitt and Precession
on Climate 121
7. Diagram of Kccentricitt and Precession. . . 122
8. Map Showing the Extent of the North and South Polar Ice... 131
9. Diagram Showing Changes of Eccentricity During Three Mill-
ion Years 1 63
10. Outline Map of the Azores 235
1 1. Map of Bermuda and the American Coast 250
1 2. Section of Bermuda and Adjacent Sea-bottom 251
13. Map of the Galapagos and Adjacent Coasts of South America.. 2C2
14. Map of the Galapagos. 263
15. Map of the South Atlantic, Showing Position of St. Helena.... 277
16. Map of the Sandwich Islands 294
17. Map of the North Pacific, with its Submerged Banks 295
IS. Map Showing the Shallow Bank Connecting the British Isles
WITH THE Continent 309
xvi MAPS AND ILLUSTRATIONS.
PAGB
19. Map of Borneo and Java, Showing the Great Submarine Bank
OF Southeastern Asia 343
20. Map of Japan and Formosa 358
21. Physical Sketch Map of Madagascar (From Nature) 378
22. Map of Madagascar Group, Showing Depths of Sea 3£0
23. Map of the Indian Ocean 389
24. Map of Celebes and the Surrounding Islands 415
25. Map Showing Depths of Sea around Australia and New Zea-
land 435
26. Map Showing the Probable Condition of Australia during the
Cretaceous Epoch 458
Part I.
THE DISPERSAL OF OEGANISMS: ITS PHENOMENA
LAWS, AND CAUSES
• • •
• • -
ISLAND LIFE.
CHAPTER I.
INTRODUCTORY.
Remnrknblo Contrnsts in Distribution of Animals. — Brituin and Jnpnn. — Australia
and New Zealand. — Bali and Lombok. — Florida and Bahama Islands. — Brazil
and Africa. — Borneo, Madagascar, and Celebes. — Problems in Distribution to bo
Found in every Country. — Can be Solved only by the Combination of many Dis-
tinct Lines of Inquiry, Biological and Physical. — Islands Offer the Best Subjects
for ti)0 Study of Distribution. — Outline of tho Subjects to be Discussed in tho
Present Volume.
When an Englishman travels by the nearest sea-route from
Great Britain to Northern Japan he passes by countries very
unlike his own, both in aspect and natural productions. Tho
sunny isles of tho Mediterranean, the sands and date-palms of
Egypt, the arid rocks of Aden, the cocoa groves of Ceylon, tho
tiger- haunted jungles of Malacca and Singapore, the fertile
plains and volcanic peaks of Luzon, the forest-clad mountains
of Formosa, and the bare hills of China, pass successively in re-
view ; till after a circuitous voyage of thirteen thousand miles
he finds himself at llakodadi in Japan, lie is now separated
from his starting-point by the whole width of Europe and
Northern Asia, by an almost endless succession of plains and
mountains, arid deserts or icy plateaux, yet when he visits the
interior of the country he sees so many familiar natural objects
that ho can hardly help fancying he is close to his home. lie
finds the woods and fields tenanted by tits, hedge-sparrows,
wrens, wagtails, larks, redbreasts, thrushes, buntings, and house-
sparrows, some absolutely identical with our own feathered
friends, others so closely resembling them that it requires a
•"•.
• •
• • •
• •
ISLAND LIFE. [Paut I.
• •• •
practisB^ ornithologist to tell the difference. If he is fond of
ina^Ats JId notices many butterflies and a host of beetles which,
ACnj^li on close examination they are found to be distinct from
onfSy are yet of the same general aspect, and seem just what
\Vniiglit be expected in any part of Europe. There are also of
course many birds and insects which are quite new and peculiar,
but these are by no means so numerous or conspicuous as to re-
move the general impression of a wonderful resemblance be-
tween the productions of such remote islands as Britain and
Yesso.
Now let an inhabitant of Australia sail to New Zealand, a dis-
tance of less than thirteen hundred miles, and he will find him-
self in a country whose productions are totally unlike those of
liis own. Kangaroos and wombats there are none, the birds are
almost all entirely new, insects are very scarce and quite unlike
the handsome or strange Australian forms, while even the veg-
etation is all changed, and no gum-tree, or wattle, or grass-tree
meets the traveller's eye.
But there are some more striking cases even than this, of the
diversity of the productions of countries not far apart. In the
Malay Archipelago there are two islands, named Bali and Lom-
bok, each about as large as Corsica, and separated by a strait
only fifteen miles wide at its narrowest part. Yet these islands
differ far more from each other in their birds and quadrupeds
than do England and Japan. The birds of the one are extreme-
ly unlike those of the other, the difference being such as to strike
even the most ordinary observer. Bali has red and green wood-
peckers, barbets, weaver-birds, and black-and-white magpie-rob-
ins, none of which are found in Lombok, where, however, we find
screaming cockatoos and friar-birds, and the strange mound-build-
ing megapodes, which arc all equally unknown in Bali. Many
of the kingfishers, crow-shrikes, and other birds, though of the
same general form, are of very distinct species; and though a
considerable number of birds are the same in both islands, the
difference is none the less remarkable — as proving that mere
distance is one of the least important of the causes which have
determined the likeness or unlikeness in the animals of different
countries.
Chap. I.] INTRODUCTORY. 6
In the western heraispliere we find equally striking examples.
The eastern United States possess very peculiar and interesting
plants and animals, the vegetation becoming more luxuriant as
we go south, but not altering in essential character, so that when
we reach the southern extremity of Florida we still find our-
selves in the midst of oaks, sumachs, magnolias, vines, and other
characteristic forms of the temperate flora ; while the birds, in-
sects, and land-shells are almost identical with those found far-
ther north. But if we now cross over the narrow strait, about
fifty miles wide, which separates Florida from the Bahama Isl-
ands, we find ourselves in a totally different country, surrounded
by a vegetation which is essentially tropical and generally iden-
tical with that of Cuba. The change is most striking, because
there is no difference of climate, of soil, or apparently of posi-
tion, to account for it ; and when we find that the birds, the in-
sects, and especially the land-shells are almost all West Indian,
while the North American typ6s of plants and animals have al-
most all completely disappeared, we shall be convinced that such
differences and resemblances cannot be due to existing condi-
tions, but must depend npon laws and causes to which mere
proximity of position offers no clew.
Hardly less uncertain and irregular are the effects of climate.
Hot countries usually differ widely from cold ones in all their
organic forms; but the difference is by no means constant, nor
does it bear any proportion to difference of temperature. Be-
tween frigid Canada and sub -tropical Florida there are less
marked differences in the animal productions than between
Florida and Cuba or Yucatan, so much more alike in climate
and 80 much nearer together. So the differences between the
birds and quadrupeds of temperate Tasmania and tropical North
Australia are slight and unimportant as compared with the enor-
mous differences we find when we pass from the latter country
to equally tropical Java. If we compare corresponding portions
of different continents, we find no indication that the almost
perfect similarity of climate and general conditions has any ten-
dency to produce similarity in the animal world. The equato-
rial parts of Brazil and of the west coast of Africa are almost
identical in climate and in luxuriance of vegetation, but their
6 ISLAND LIFE. [Part I.
animal life is totally diverse. In the former we liave tapirs,
sloths, and prehensile-tailed monkeys ; in the latter, elephants,
antelopes, and man-like apes ; while among birds, the toucans,
chatterers, and humming-birds of Brazil are replaced by the
plantain-eaters, bee-eaters, and sun-birds of Africa. Parts of
South -temperate America, South Africa, and South Australia
correspond closely in climate; yet the birds and quadrupeds of
these three districts are as completely unlike each other as those
of any parts of the world that can be named.
If we visit the great islands of the globe, we lind that they
present similar anomalies in their animal productions, for while
some exactly resemble the nearest continents, others are widely
different. Thus the quadrupeds, birds, and insects of Borneo
correspond very closely to those of the Asiatic continent, while
those of Madagascar are extremely unlike African forms, al-
though the distance from the continent is less in the latter case
than in the former. And if we compare the three great islands
Sumatra, Borneo, and Celebes — lying, as it were, side by side in
the same ocean — we find that the two former, although farthest
apart, have almost identical productions, while the two latter,
though closer together, are more unlike than Britain and Japan,
situated in different oceans and separated by the largest of the
great continents.
These examples will illustrate the kind of questions it is the
object of the present work to deal with. Every continent, ev-
ery country, and every island on the globe offer similar problems
of greater or less complexity and interest, and the time has now
airived when their solution can be attempted with some prospect
of success. Many years' study of this class of subjects has con-
vinced me that there is no short and easy method of dealing
with them ; because they arc, in their very nature, the visible
outcome and residual product of the whole past history of the
earth. If we take the organic productions of a small island, or
of any very limited tract of country, such as a moderate-sized
country parish, we have, in their relations and affinities — in the
fact that they are there and others are not there, a problem which
involves all the migrations of these species and their ancestral
forms — all the vicissitudes of climate and all the changes of sea
Chap. I.] INTRODUCTORY. 7
and land which have affected those migratioils — the whole series
of actions and reactions which have determined the preservation
of some forms and the extinction of othere — in fact, the whole
history of the earth, inorganic and organic, throughout a large
portion of geological time.
We shall perhaps better exhibit the scope and complexity of
the subject, and "show that any intelligent study of it was almost
impossible till quite recently, if we concisely enumerate the great
mass of facts and the number of scientific theories or principles
which are necessary for its elucidation.
We require, then, in the first place, an adequate knowledge of
the fauna and flora of the whole world, and even a detailed
knowledge of many parts of it, including the islands of more
special interest and their adjacent continents. This kind of
knowledge is of very slow growth, and is still very imperfect ;*
and in many cases it can never now be obtained, owing to the
reckless destruction of forests, and with them of countless spe-
cies of plants and animals. In the next place, we require a true
and natural classification of animals and plants, so that we may
know their real aflinities ; and it is only now that this is being
* I cannot avoid here referring to the enormous waste of labor and money with
comparatively scanty and unimportant results to natural history of most of the great
scientific voyages of the various civilized governments during the present centui*}*.
All these expeditions combined have done fur less than private collectors in making
known the products of remote lands and islands. They have brought home fragmen-
tary collections, made in widely scattered localities, and these have been usually do-
scribed in huge folios, whose value is often in inverse proportion to their bulk and
cost. The same species have been collected again and again, often described several
times over under new names, and not unfrequcntly stated to be from places they
never inhabited. The result of this wretched system is that the productions of some
of the most frequently visited and most interesting islands on the globe are still very
imperfectly known, while their native plants and animals are being yearly exterminat-
ed ; and this is the case even with countries under the rule or protection of Euro-
pean governments. Such are the Sandwich Islands, Tahiti, the Marquesas, the Phil-
ippine Islands, and a host of smaller ones ; while Bourbon and Mauritius, St. Helena,
and several others have only been adequately explored after an important portion of
their productions has been destroyed by cultivation or the reckless introduction of
goats and pigs. The employment in each of our possessions, and those of other Eu-
ropean powers, of a resident naturalist at a very small annual expense, would have
done more for the advancement of knowledge in this direction than all the expensive
expeditions that have again and again circumnavigated the globe.
8 ISLAND LIFE. [Part L
generally arrived at. We further have to make use of the the-
ory of " descent with modification " as the only possible key to
the interpretation of the facts of distribution ; and this theory
has only been generally accepted within the last twenty years.
It is evident that, so long as the belief in " special creations "
of each species prevailed, no explanation of tlie complex facts
of distribution could be arrived at or even conceived ; for if each
species was created where it is now found, no further inquiry
can take us beyond that fact, and there is an end of the whole
matter. Another important factor in our interpretation of the
phenomena of distribution is a knowledge of the extinct forms
that have inhabited each country during the tertiary and sec-
ondary periods of geology. Xew facts of this kind are daily
coming to light, but except as regards Europe, North America,
and parts of India, they are extremely scanty ; and even in the
best-known countries the record itself is often very defective
and fragmentary. Yet we have already obtained remarkable
evidence of the migrations of many animals and plants in past
ages, throwing an often unexpected light on the actual distri-
bution of many groups.* By this means alone can we obtain
positive evidence of the past migrations of organisms ; and when,
as too frequently is the case, this is altogether wanting, we have
to trust to collateral evidence and more or less probable hypo-
thetical explanations. Hardly less valuable is the evidence of
stratigraphical geology ; for this often shows us what parts of a
country have been submerged at certain epochs, and thus ena-
bles us to prove that certain areas have been long isolated, and
the fauna and flora allowed time for special development. Here,
too, our knowledge is exceedingly imperfect, though the blanks
upon the geological map of the world are yearly diminishing in
extent. Lastly, as a most valuable supplement to geology, we
require to know the exact depth and contour of the ocean-bed,
since this affords an important clew to the former existence of
now submerged lands, uniting islands to continents, or affording
intermediate stations which have aided the migrations of many
' The general facts of Palaeontology, as bearing on the migrations of animal
groups, are summarized in my ** Geographical Distribution of Animals," Vol. L,
Chapters VL, VH., and VIH.'
Chap. I.J INTRODUCTORY. 9
organisms. Tliis kind of information has only begun to be ob-
tained during the last few years ; and it will be seen in the latter
part of this volume that some of the most recent deep-sea sound-
ings have affoi*ded a basis for an explanation of one of the most
difficult and interesting questions in geographical biology — the
origin of the fauna and flora of New Zealand.
Such are the various classes of evidence that bear directly on
the question of the distribution of organisms; but there are
others of even a more fundamental character, and the impor-
tance of which is only now beginning to be recognized by stu-
dents of nature. These are, firstly, the wonderful alterations of
climate which have occurred in the temperate and polar zones,
as proved by the evidences of glaciation in the one and of luxu-
riant vegetation in the other ; and, secondly, the theory of the
permanence of existing continents and oceans. If glacial epochs
in temperate lands and mild climates near the poles have, as now
believed by men of eminence, occurred several times over in the
past history of the earth, the effects of such great and repeated
changes, both on the migration, modification, and extinction of
species, must have been of overwhelming importance — of more
importance, perhaps, than even the geological changes of sea and
land. It is therefore necessary to consider the evidence for
these climatal changes ; and then, by a critical examination of
their possible causes, to ascertain whether they were isolated phe-
nomena, were due to recurrent cosmical actions, or were the re-
sult of a great system of terrestrial development. The latter is
the conclusion we arrive at ; and this conclusion brings with it
the conviction that, in the theory which accounts for both gla-
cial epochs and warm polar climates, we have the key to explain
and harmonize many of the most anomalous biological and geo-
logical phenomena, and one which is especially valuable for the
light it throws on the dispersal and existing distribution of or-
ganisms. The other important theory, or rather corollary from
the preceding theory — that of the permanence of oceans and the
general stability of continents throughout all geological time — is
as yet very imperfectly understood, and seems, in fact, to many
persons in the nature of a paradox. The evidence for it, how-
ever, appears to mo to be conclusive ; and it is certainly the
10 ISLAND LIFE. [Pabt L
raost fundamental question in regard to the subject we have to
deal witli ; since, if we once admit that continents and oceans
may have changed places over and over again (as many writei^s
maintain), we lose all power of reasoning on the migrations of
ancestral forms of life, and are at the mercy of every wild theo-
rist who chooses to imagine the former existence of a now sub-
merged continent to explain the existing distribution of a group
of frogs or a genus of beetles.
As already shown by the illustrative examples adduced in this
chapter, some of the most remarkable and interesting facts in
the distribution and affinities of organic forms are presented by
islands in relation to each other and to the surrounding conti-
nents. The study of the productions of the Galapagos — so pe-
culiar, and yet so decidedly related to the American continent
— appears to have had a powerful influence in determining the
direction of Mr. Darwin's researches into the origin of species ;
and every naturalist who studies them has always been struck
by the unexpected relations or singular anomalies which are so
often found to characterize the fauna and flora of islands. Yet
their full importance in connection with the history of the earth
and its inhabitants has hardly yet been recognized ; and it is in
order to direct the attention of naturalists to this most promis-
ing field of research that I restrict myself in this volume to an
elucidation of some of the problems they present to us. By far
the larger part of the islands of the globe are but portions of
continents undergoing some of the various changes to which
they are ever subject ; and the correlative statement, that every
'7 '^ ' ESJ't ^^ ^^^^ continents have again and again passed through in-
sular conditions, has not been sufficiently considered, but is, I
believe, the statement of a great and most suggestive truth, and
one which lies at the foundation of all accurate conception of
the physical and organic changes which have resulted in the
present state of the earth.
The indications now given of the scope and purpose of the
present volume render it evident that, before we can proceed
to the discussion of the remarkable phenomena presented by
insular faunas and floras, and the complex causes which have
produced them, we must go through a series of preliminary
Chap. I.] INTRODUCTORY. 11
studies, adapted to give us a command of the more important
facts and principles on wbicli the solution of such problems
depends. The succeeding eight chapters will, therefore, be de-
voted to the explanation of the mode of distribution, variation,
modification, and dispersal of species and groups, illustrated by
facts and examples; of the true nature of geological change
as affecting continents and islands; of changes of climate, their
nature, causes, and effects ; of the duration of geological time
and the rate of organic development.
12 ISLAND LIFE. [Part L
CHAPTER 11.
THE ELEMENTARY FACTS OF DISTRIBUTION.
Importance of LocaJity ns an Essential Character of Species. — Areas of Distribution.
— Extent and Limitations of Specific Areas. — Specific Range of Bird:?. — Generic
Areas. — Separate and Overlapping Areas. — The Species of Tits as Illustrating
Areas of Distribution. — The Distribution of the Species of Jays. — Discontinuous
Generic Areas. — Peculiarities of Generic and Family Distribution. — General Feat-
ures of Overlapping and Discontinuous Areas. — Restricted Areas of Families. —
The Distribution of Orders.
So long as it was believed that the several species of animals
and plants were "special creations," and had been formed ex-
pressly to inhabit the countries in which they are now found,
their habitat was an ultimate fact which required no explana-
tion. It was assumed that every animal was exactly adapted
to the climate and surroundings amid which it lived, and that
the only, or, at all events, the chief, reason why it did not in-
habit another country was, that the climate or general condi-
tions of that country were not suitable to it, but in what the
unsuitability consisted wo could rarely hope to discover. Hence
the exact locality of any species was not thought of much im-
portance from a scientific point of view, and the idea that any-
thing could be learned by a comparative study of different floras
and faunas never entered the minds of the older naturalists.
But so soon as the theory of evolution came to be generally
adopted, and it was seen that each animal could only have come
into existence in some area where ancestral forms closely allied
to it already lived, a real and important relation was established
between an animal and its native countr}*, and a new set of
problems at once sprang into existence. From the old point of
view, the diversities of animal life in the separate continents,
even where physical conditions were almost identical, was the
fact that excited astonishment; but seen by the light of the
chap.il] the elementary facts of distribution. 13
evolution theory, it is the resemhlances rather than the diversi-
ties in these distant continents and islands that are most difficult
to explain. It thus comes to be admitted that a knowledge of
the exact area occupied by a species or a group is a real portion
of its natural history, of as much importance as its habits, its
structure, or its affinities ; and that we can never arrive at any
trustworthy conclusions as to how the present state of the or-
ganic world was brought about until we have ascertained with
some accuracy the general laws of the distribution of living
things over the earth's surface.
Areas of Distribution, — Every species of animal has a certain
area of distribution to which, as a rule, it is permanently con-
fined, althougli, no doubt, the limits of its range fluctuate some-
what from year to year, and in some exceptional cases may be
considerably altered in a few years or centuries. Each species
is moreover usually limited to one continuous area, over the
whole of which it is more or less frequently to be met with ;
but there are many partial exceptions to this rule. Some ani-
mals are so adapted to certain kinds of country — as to forests
or marshes, mountains or deserts — that they cannot live long
elsewhere. These may be found scattered over a wide area in
suitable spots only, but can hardly on that account be said to
liave several distinct areas of distribution. As an example, we
may name the chamois, which lives only on high mountains,
but is found in the Pyrenees, the Alps, the Carpathians, in
some of the Greek mountains and the Caucasus. The variable
hare is another and more remarkable case, being found all over
Northern Europe and Asia, beyond lat. 55°, and also in Scot-
land and Ireland. In Central Europe it is unknown till we come
to the Alps, the Pyrenees, and the Caucasus, where it again ap-
pears. This is one of the best cases known of the discontinuous
distribution of a species^ there being a gap of about a thousand
miles between its southern limits in Eussia and its reappearance
in the Alps. There are, of course, numerous instances in which
species occur in two or more islands, or in an island and con-
tinent, and are thus rendered discontinuous by the sea, but these
involve questions of changes in sea and land which we shall
have to consider further on. Other cases are believed to exist
14 ISLAND LIFE. [Pabt L
of still wider separation of a species, as with the marsh titmice
and the reed buntings of Europe and Japan, where similar forms
are found in the extreme localities, while a distinct variety, race,
or sub-species inhabits the intervening district.
Extent and Limitations of Specific Areas, — Leaving for the
present these cases of want of continuity in a species, we find
the most wide diflEerence between the extent of country occu-
pied, varying, in fact, from a few square miles to almost the en-
tire land surface of the globe. Among the mammalia, however,
the same species seldom inhabits both the old and new worlds,
unless they are strictly arctic animals, as the reindeer, elk, and
arctic fox, the glutton, the ermine, and some others. The com-
mon wolf of Europe and Northern Asia is thought by many
naturalists to be identical wuth the variously colored wolves of
North America extending from the Arctic Ocean to Mexico, in
which case this will have, perhaps, the widest range of any spe-
cies of mammal. Little doubt exists as to the identity of the
brown bears and the beavers of Europe and North America ; but
all these species range up to the Arctic circle, and there is no
example of a mammal universally admitted to bo identical yet
confined to the temperate zones of the two hemispheres. Among
the undisputed species of mammalia, the leopard has an enor-
mous range, extending all over Africa and South Asia to Bor-
neo and the east of China, and thus having probably the widest
range of any known mammal. The winged mammalia have
not usually very wide ranges, there being only one bat common
to the Old and New Worlds. This is a British species, Vespe-
rugo serotinus^ which is found over the larger part of North
America, Europe, and Asia, as far as Pckin, and even extends
into tropical Africa, thus rivalling the leopard and the wolf in
the extent of country it occupies.
Of very restricted ranges there are many examples, but some
of these are subject to doubts as to the distinctness of the spe-
cies or as to its geogmphical limits being really known. In
Europe we have a distinct species of ibex {Capra Pyrenaica)
confined to the Pyrenean mountains, while the true marmot is re-
stricted to the Alpine range. More remarkable is the Pyrenean
water-mole {Mygale Pijrenaica\ a curious small insectivorous
Chap. II.] THE ELEMENTARY FACTS OF DISTIUBUTION. 15
animal found only in a few places in the northern valleys of tho
PjTcnees. In islands there are many cases of undoubted re-
striction of species to a small area, but these involve a different
question from the range of species on continents where there
is no apparent obstacle to their wider extension.
Specific Range of Birds. — Among birds we find instances of
much wider range of species, which is only what might be ex-
pected considering their powers of flight ; but, what is very
curious, we also find more striking (though perhaps not more
frequent) examples of extreme limitation of range among birds
than among mammals. Of the former phenomenon perhaps
the most remarkable case is that afforded by the osprey, or fish-
ing-hawk, which ranges over the greater portion of all the con-
tinents, as far as Bmzil, South Africa, the Malay Islands, and
Tasmania. The barn-owl {Strix fiammed) has nearly as wide a
range, but in this case there is more diversity of opinion as
to the specific difference of many of the forms inhabiting re-
mote countries, some of which seem undoubtedly to be distinct.
Among passerine birds the raven lias probably the widest range,
extending from the Arctic regions to Texas and New Mexico in
America, and to North India and Lake Baikal in Asia; while
the little northern willow-wren {PhyUoscopus horealis) ranges
from Norway across Asia to Alaska, and southward to Ceylon,
China, Borneo, and Timor.
Of very restricted continental ranges the best examples in
Europe are the little blue magpie {Cyanopica Cooki) confined to
the central portions of the Spanish peninsula ; and the Italian
sparrow found only in Italy and Corsica. In Asia, Palestine
affords some examples of birds of very restricted range — a beau-
tiful sun-bird {Nectarinea osea\ a peculiar starling {Aniydrus
Trisiramii)^ and some others, being almost or quite confined to
the warmer portions of the valley of the Jordan. In the Him-
alayas there are numbers of birds which have very restricted
ranges ; but those of the Neilgherries are perhaps better known,
several species of laughing thrushes and other birds being found
only on the summits of these mountains. The most wonder-
fully restricted ranges are, however, to be found among the
humming-birds of tropical America. The great volcanic peaks
16 ISLAND LIFE. [Part L
of Cliimborazo and Pichincha have each a peculiar species of
humming-bird confined to a belt just below the limits of per-
petual snow, while the extinct volcano of Chiriqui, in Veragua,
has a species confined to its wooded crater. One of the most
strange and beautiful of the humming-birds {Loddigesia mira-
hilis) was obtained once only, more than forty years ago, near
Chachapoyas, in the Andes of Northern Peru ; and though Mr.
Gould lias sent many drawings of the bird to people visiting
the district, and has for many years offered a high reward for
a specimen, no other has ever been seen I *
The above details will sufficiently explain what is meant by
the "specific area" or range of a species. Tlie very wide and
very narrow ranges are exceptional, the great majority of spe-
cies both of mammals and birds ranging over moderately wide
areas, which present no striking contrasts in climate and physical
conditions. Thus a large proportion of European birds range
over the whole continent in an east and west direction, but con-
siderable numbers are restricted either to the northern or the
southern half. In Africa some species range over all the conti-
nent south of the desert, while large numbers are restricted to
the equatorial forests, or to the upland plains. In North Amer-
ica, if we exclude the tropical and the arctic portions, a consider-
able number of species range over all the temperate parts of the
continent, w^hile still more are restricted to the east, the centre,
or the west, respectively.
Generic Areas, — Having thus obtained a tolerably clear idea
of the main facts as to the distribution of isolated species, let
us now consider those collections of closely allied species termed
genera. What a genus is will be sufficiently understood by a
few illustrations. All the different kinds of dogs, jackals, and
wolves belong to the dog genus, Canis; the tiger, lion, leopard,
jaguar, and the wild-cats, to the cat genus, Felis; the blackbird,
song- thrush, missel -thrush, fieldfare, and many others, to the
thrush genus, Turdus; the crow, rook, raven, and jackdaw, to
the crow genus, Corvus; but the magpie belongs to another,
' Since these lines were written, the report comes tlmt fresh specimens
hnve been found in the same locality.
Chap. II.] THE ELEMENTARY FACTS OF DISTRIBUTION. 17
though closely allied genus, Pica, distinguished by the different
form and proportions of its wings and tail from all the species
of the crow genus. The number of species in a genus varies
greatly from one up to several hundreds. The giraffe, the glut-
ton, the walrus, the bearded reedling, the secretary-bird, and
many others, have no close allies, and each forms a genus by
itself. The beaver genus, Castor, and the camel genus, Camelns,
each consist of two species. On the other hand, the deer genus,
Cervus, has forty species ; the mouse and rat genus, Mus, more
than a hundred species ; and there is about the same number of
the thrush genus; while among the lower classes of animals
genera are- often very extensive, the fine genus Papilio, or swal-
low-tailed butterflies, containing more than four hundred spe-
cies; and Cicindela, which includes our native tiger beetles, has
about the same number. Many genera of shells are very ex-
tensive, and one of them — tlie genus Ilelix, including the com-
monest snails, and ranging all over the world — is probably the
most extensive in the animal kingdom, numbering about two
thousand described species.
Separate and Overlapping Areas. — The species of a genus are
distributed in two ways. Either they occupy distinct areas which
do not touch each other and are sometimes widely separated, or
they touch and occasionally overlap each other, each species oc-
cupying an area of its own which rarely coincides exactly with
that of any other species of the same genus. In some eases,
-when a river, a mountain-chain, or a change of conditions, as from
pasture to desert or forest, determines the range of species, the
areas of two species of the same genus may just meet, one be-
ginning where the other ends ; but this is comparatively rare.
It occurs, however, in the Amazon valley, where several species
of monkeys, birds, and insects come up to the south bank
of the river, but do not pass it, while allied species come to the
north bank, which in like manner forms their boundary. As
examples we may mention that one of the Saki monkeys {Piihe-
cia mona^chus?) comes up to the south bank of the Upper Ama-
zon, while immediately we cross over to the north bank we find
another species {Pithecia rufiharhata ?), Among birds we have
the green jacamar {Galhda viriJis) abundant on the north bank
2
18 ISLAND LIFE. [Part L
of the Lower Amazon, while on the south bank we have two
allied species {GaUbxda 7'ufoviridis and G. cj/aneicoUis); and
among insects we have at Sautarem, on the south bank of the
Amazon, the beautiful blue butterfly CaUithea sapphira^ while
almost opposite to it, at Monte-alegre, an allied species, CaUithea
Leprieuri^ is alone found. Perhaps the most interesting and
best-known case of a series of allied species whose ranges are
separate but conterminous is that of the beautiful South Amer-
ican wading birds, called trun)peters, and forming the genus
Psophia. There are five species, all found in the Amazon valley,
but each limited to a well-marked district bounded by great
rivers. On the north bank of the x\mazon there are two species,
one in its lower valley extending up to the Kio Negro, and the
other in the central part of the valley beyond that river; while
to the south of the Amazon there are three, one above the Ma-
deira, one below it, and a third near Para, probably separated
from the last by the Tocantins River.
Overlapping areas among the species oi a genus is a more
common phenomenon, and is almost universal where these spe-
cies are numerous in the same continent. It is, however, ex-
ceedingly irregular, so that we often find one species extending
over a considerable portion of the area occupied by the genus,
and including the entire areas of some of the other species. So
little has been done to work out accurately the limits of species
that it is very difficult to give examples. One of the best is to
be found in the genus Dendroeca, a group of American wood-
warblers. These little birds all migrate in the winter into the
tropical regions, but in the summer they come north, each hav-
ing its particular range. Thus, D. Domhiica comes as far as
South Caroliuii, D, cchrulea to Virginia, D. discolor to Southern
Maine and Canada; four other species go farther north in Ca-
nada, while five more extend to the borders of the Arctic zone.
The /Species of llts as Illustrating Areas of Distribution, — In
our own hemisphere the overlapping of allied species may be
well illustrated by the various kinds of titmice, several of which
are among our best-known Plnglish birds. The great titmouse
{Panis major) has the widest range of all, extending from the
Arctic circle to Algeria, Palestine, and Persia, and from Ireland
CujLP.ll.] THE ELExMENTABY FACTS OF DISTRIBUTION. 19
riglit across Siberia to the Ochotsk Sea, probably following tlio
great northern forest belt. It does not extend into China and
Japan, where distinct species are found. Next in extent of
range is the coal tit {Pants ater\ which inhabits all Europe,
from the Mediterranean to about 64° N. latitude ; in Asia Minor
to the Lebanon and Caucasus ; and across Siberia to Amoorland.
The marsh tit {Parua palitstris) inhabits temperate and south
Europe from 61° N. latitude in Norway to Poland and South-
west Russia, and in the south from Spain to Asia Minor. Close-
ly allied to this — of which it is probably only a variety or sub-
species— is the northern marsh tit {Parus horeaUs)^ which over-
laps the last in Norway and Sweden, and also in South Russia
and the Alps, but extends farther north into Lapland and North
Russia, and thence probably in a southeasterly direction across
Central Asia to North China. Yet another closely allied species
(Parus Camtschatkensis) ranges from Northeastern Russia across
Northern Siberia to Lake Baikal and to Hakodadi in Japan, thus
overlapping Parus horealis in the western portion of its area.
Our little favorite, the blue tit {Parus cosruleus)^ ranges over all
Europe from the Arctic circle to the Mediterranean, and on to
Asia Minor and Persia, but does not seem to pass beyond the
Ural Mountains. Its lovely eastern ally, the azure tit {Parus
cyaneus\ overlaps the range of P. eoeruleus in Western Europe
as far as St, Petersburg and Austria, rarely straggling to Den-
mark, while it stretches all across Central Asia between the lati-
tudes 35° and 56° N. as far as the Amoor valley. Besides these
wide-ranging species, there are several others which are more re-
stricted. Panis TeneriffcBj a beautiful dark-blue form of our
blue tit, inhabits Northwest Africa and the Canaries ; Parus Le-
douci^ closely allied to our coal tit, is found only in Algeria ;
Parus Ivguhris^ allied to the marsh tit, is confined to Southeast
Europe and Asia Minor, from Hungary and South Russia to Pal-
estine ; and Parus cinctuSy another allied form, is confined to
the extreme north in Lapland, Finland, and perhaps Northern
Russia and Siberia. Another beautiful little bird, the crested
titmouse {Parus crisiatus\ is sometimes placed in a separate ge-
nns. It inhabits nearly all Central and South Europe, wherever
there are pine forests, from 64° N. latitude to Austria and North
20 ISLAND LIFE. [Part I.
Italy, and in the west to Spain and Gibraltar, while in the east
it does not pass the Urals and the Caucasus range. Its nearest
allies are in the high Himalayas.
These are all the European tits, but there are many others in-
habiting Asia, Africa, and North America ; so that the genus
Parus has a very 'wide range, in Asia to Ceylon and the Malay
Islands, in Africa to the Cape, and in North America to the
higlilands of Mexico.
The Dutributioii of the Specie of Jays. — Owing to the very
wide range of several of the tits, the uncertainty of the specific
distinction of others, and the difficulty in many cases of ascer-
taining their actual distribution, it has not been found practica-
ble to illustrate this genus by means of a map. For this pur-
pose we have chosen the genus Garrulus, or the jays, in which
the species are less numerous, the specific areas less extensive,
and the species generally better defined ; while, being large and
handsome birds, they are sure to have been collected, or at least
noticed, wherever they occur. There are, so far as yet known,
twelve species of true jays, occupying an area extending from
Western Europe to Eastern Asia and Japan, and nowhere pass-
ing the Arctic circle to the north, or the Tropic of Cancer to the
south, so that they constitute one of the most typical of the Pa-
laearctic' genera. The following are the species, beginning with
the most westerly and proceeding towards the east. The num-
bers prefixed to each species correspond to those on the colored
map which forms the frontispiece to this volume.
1. Garrulus glundarius, the common jay, inhabits the Brit-
ish Isles and all Europe except the extreme north, extending
also into North Africa, where it has been observed in many
parts of Algeria. It occurs near Constantinople, but apparently
not in Asia Minor, and in Kussia up to, but not beyond, the
Urals. The jays, being woodland birds, are not found in open
plains or barren nplands, and their distribution is hence by no
means uniform within the area they actually occupy.
2. Garrulus cetmcalls, the Algerian jay, is a very distinct
* The Pnlflcarctic region includes tempcnitc Asia and Europe, ns will be explained
the next choDter.
in the next chapter
CiiAP.IL] THE ELEMENTARY FACTS OF DISTRIBUTION. 21
species inhabiting a limited area in North Africa, and found in
some places along with the common species.
3. Garrulus Krynicki^ the black-headed jay, is closely allied
to the common species, but quite distinct, inhabiting a compara-
tively small area in Southeastern Europe and Western Asia.
4. Garrulus atricapiUus^ the Syrian jay, is very closely al-
lied to the last, and inhabits an adjoining area in Syria, Pales-
tine, and Southern Persia.
5. GarrviLus hyrcanus^ the Persian jay, is a small species al-
lied to our jay, and only known from tlio Elburz Mountains in
the north of Persia.
6. Gan^ulus Brandti^ Brandt's jay, is a very distinct species,
having an extensive range across Asia from the Ural Mountains
to North China, Mandchuria, and the northern island of Japan,
and also crossing the Urals into Eussia, where it has been found
as far west as Kazan in districts where the common jay also
occurs.
7. Garrulus lanc€ol<itu8^ the black-throated jay, is a very dis-
tinct form known only from the Northwesteni Himalayas and
Nepal, common about Simla, and extending into Cashmere be-
yond the range of the next species.
8. Garrulus hispecularis^ the Himalayan jay, is also very dis-
tinct, having the head colored like the back, and not striped as
in all tlie western species. It inhabits the Himalayas east of
Cashmere, but is more abundant in the western tlian the eastern
division, though, according to the Abbe David, it reaches Mou-
pin in East Thibet.
9. Garrulus Sinensis^ the Chinese jay, is very closely allied
to the Himalayan, of which it is sometimes classed as a sub-spe-
cies. It seems to be found in all tlie southern mountains of
China, from Foochow on the east to Sze-chuen and East Thibet
on the west, as it is recorded from Moupin by the Abbe David
as well as the Himalayan bird — a tolerable proof that it is a dis-
tinct form.
10. Garrulus taivanus^ the Formosan jay, is a very close ally
of the preceding, confined to the island of Formosa.
11. Garrulus JaponicuSj the Japanese jay, is very closely
allied to our common British species, being somewhat smaller
22 ISLAND LIFE. [Pjlrt L
and less brightly colored, and with black orbits ; yet these are
the most widely separated species of the genus.
12. Garrvliis Lidthi. — This is the handsomest of all the jays,
the head, neck, and wings being azure blue. Its locality was
long doubtful, but it has now been ascertained to inhabit Japan,
where it is evidently very rare, its exact habitat being still un-
known.
In the accompanying map (see frontispiece) we have laid down
the distribution of each species so far as it can be ascertained
from the works of Sharpe and Dresser for Europe, Jerdon for
India, Swinhoe for China, and Messrs. Blakiston and Pryer for
Japan. There is, however, much uncertainty in many places, and
gaps have to be filled up conjecturally, while such a large part
of Asia is still very imperfectly explored that considerable mod-
ifications may have to be made when the country becomes more
accurately known. But though details may be modified, we can
hardly suppose that the great features of the several specific
areas, or their relations to each other, will be much affected ; and
these are what we have chiefly to consider as bearing on the
questions here discussed.
The first thing that strikes us on looking at the map is the
small amount of overlapping of the several areas, and the isola-
tion of many of the species ; while the next most striking feat-
ure is the manner in which the Asiatic species almost surround
a vast area in which no jays are found. The only species with
large areas are the European 6r. glandarius and the Asiatic G,
Brandti, The former has three species overlapping it — in Al-
geria, in Southeastern and in Northeastern Europe respectively.
The Syrian jay (No. 4) is not known to occur anywhere with the
black-headed jay (No. 3), and perhaps the two areas do not meet.
The Persian jay (No. 5) is quite isolated. The Himalayan and
Chinese jays (Nos. 7, 8, and 9) form a group which arc isolated
from the rest of the genus; while the Japanese jay (No. 11) is
also completely isolated as regards the European jays, to which
alone it is closely allied. These peculiarities of distribution are
no doubt in part dependent on the habits of the jays, which live
only in well-wooded districts, among deciduous trees, and are es-
sentially non-migratory in their habits, though sometimes moving
Chap.it.] the elementary facts of DISTKICUTION. 23
southward in winter. This will explain their absence from the
vast desert area of Central Asia, but it will not account for the
gap between the North and South Chinese species, nor for the
absence of jays from the wooded hills of Turkestan, where Mr.
N. A. Severtzoff collected assiduously, obtaining 384 species of
birds, but no jay. These peculiarities, and the fact that jays are
never very abundant anywhere, seem to indicate that the genus
is now a decaying one, and that it has at no very distant epoch
occupied a larger and more continuous area, such as that of the
genus Parus at the present day.
Discontinuous Generic Areas, — It is not very easy to find good
examples of genera whose species occupy two or more quite dis-
connected areas, for though such cases may not be rare, we are
seldom in a position to mark out the limits of the several species
with sufficient accuracy. The best and most remarkable case
among European birds is that of the blue magpies, forming the
genus Cyanopica. One species ((7. Coohi) is confined (as already
stated) to the wooded and mountainous districts of Spain and
Portugal, while the only other species of the genus (C. cyanus)
is found far away in Northeastern Asia and Japan, so that the
two species are separated by about 5000 miles of continuous
land. Another case is that of the curious little water-moles form-
ing the genus Mygale, one species, M. Muscovitica, being found
only on the banks of the Volga and Don in Southeastern Rus-
sia, while the other, M, Pyrenaica^ is confined to streams on the
northern side of the Pyrenees. In tropical America there are
four different kinds of bell-birds belonging to the genus Chas-
morhynchns, each of which appeare to inhabit a restricted area
completely separated from the others. The most northerly is
C tricamncxdatus of Costa Kica and Veragua, a brown bird with
a white head and three long caruncles growing upwards at the
base of the beak. Next comes C. variegatus^ in Venezuela, a
white bird with a brown head and numerous caruncles on the
throat, perhaps conterminous with the last ; in Guiana, extending
to near the month of the Kio Negro, we have C. 7iiveus^ the bell-
bird described by Waterton, which is pure white, with a single
long fleshy caruncle at the base of the beak ; the last species, C.
nndicoUisy inhabits Southeast Brazil, and is also white, but with
24: ISLAND LIFE. [Part I.
black stripes over the eyes, and with a naked throat. Tliese birds
are about the size of thrushes, and are all remarkable for their
loud-ringing notes like a bell or a blow on an anvil, as well as
for their peculiar colors. They are therefore known to the na-
tive Indians wherever they exist, and we may be the more sure
that they do not spread over the intervening areas where they
have never been found, and where the natives know nothing of
them.
A good example of isolated species of a group nearer home is
afforded by the snow-partridges of the genus Tetraogallus. One
species inhabits the Caucasus range and nowhere else, keeping to
the higher slopes from 6000 to 11,000 feet above the sea, and
accompanying the ibex in its wanderings, as both feed on the
same plants. Another has a wider range in Asia Minor and
Persia from the Taurus Mountains to the southeast corner of
the Caspian Sea ; a third species inhabits the Western Hima-
layas, between the forests and perpetual snow, extending east-
ward to Nepal, while a fourth is found on the north side of the
mountains in Thibet, and the mnges of these two perhaps over-
lap; the last species inhabits the Altai Mountains, and like the
two first appears to be completely separated from all its allies.
There are some few still more extraordinarv cases in which
the species of one genus are separated in remote continents or
islands. The most striking of these is that of the tapirs, forming
the genus Tapirus, of which there are two or three species in
South America, and one very distinct species in Malacca and
Borneo, separated by nearly half the circumference of the globe.
Another example among quadrupeds is a peculiar genus of moles
named Urotrichus, of which one species inhabits Japan and the
other British Columbia. The cuckoo-like honey-guides, forming
the genus Indicator, are tolerably abundant in tropical Africa,
but there arc two outlying species, one in the Eastern Himalaya
Mountains, the other in Borneo, both very rare, and quite re-
cently an allied species has been found in the Malay peninsula.
The beautiful blue and green thrush -tits, forming the genus
Cochoa, have two species in the Eastern Himalayas, while the
third is confined to Java; the curious genus Eupetes, supposed
to be allied to the dippers, has two species in Sumatra, and the
Chap. II.] THE ELEMENTARY FACTS OF DISTRIBUTION. 25
other species two thousand miles distant in New Guinea; lastly,
the lovely ground-thrushes of the genus Pitta range from Hin-
dostan to Australia, while a single species, far removed from all
its near allies, inhabits West Africa.
Peculiarities of Generic and Family Distribution. — The ex-
amples now given sufficiently illustrate the mode in which the
several species of a genus are distributed. We have next to
consider genera as the component parts of families, and families
of orders, from the same point of view.
All the phenomena presented by the species of a genus are
reproduced by the genera of a family, and often in a more
marked degree. Owing, however, to the extreme restriction of
genera by modern naturalists, there are not many among the
higher animals that have a world-wide distribution. Among
the mammalia there is no such thing as a truly cosmopolitan
genus. This is owing to the absence of all the higher orders ex-
cept the mice from Australia, while the genus Mus, which oc-
curs there, is represented by a distinct group, Hesperomys, in
America. If, however, we consider the Australian dingo as a
native animal, we might class the genus Canis as cosmopolite,
but the wild dogs of South America are now formed into sep-
arate genera by some naturalists. Many genera, however, range
over three or more continents, as Felis (the cat genus), absent
only from Australia ; Ursus (the bear genus), absent from Aus-
tralia and tropical Africa ; Cervus (the deer genus), with nearly
the same range; and Scinrus (the squirrel genus), found in all
the continents but Australia. Among birds, Turdus, the thrush,
and Hirundo, the swallow genus, are the only perching birds
which are truly cosmopolites; but there are many genera of
hawks, owls, wading and swimming birds which have a world-
wide range.
As a great many genera consist of single species, there is no
lack of cases of great restriction, such as the curious lemur called
the " potto," which is found only at Sierra Leone, and forms
the genus Perodicticus ; the true chinchillas, found only in the
Andes of Peru and Chili south of 9° S. lat. and between 8000
and 12,000 feet elevation ; several genera of finches, each con-
fined to limited portions of the higher Himalayas ; the blood-
ISLAND LIFE.
CPaht I.
plicasaiits (Ithaginis), found only above 10,000 feet from Nepal
to East Thibet ; the bald-licaded starling of the Philippine Isl-
ands, the lyre-birds of East Australia, and a host of others.
It ia among the different genera of the eanie family that we
meet with the moat Btriking examplea of diacontiuuity, although
these genera are often as nnmistakably allied as are the Epecies
of A genus ; and it is these cnecs that furnish the most intereat-
iug problems to the student of distribution. We must, there-
fore, consider them somewhat more fully.
Among mammalia the most remarkable of these divided fam-
ilies is that of the camels, of which one genus. Camel ue, the trne
eamele, coinpriBing the camel and dromedary, is confined to
Asia, while the other, Auchenia, comprising the llamas and
alpacas, is found only in the high Andes and in the plains of
temperate South Ameriea, Not only wro these two genera sep-
arated by the Atlantic and by the greater part of the land of
two continents, but one is eontined to the Northern and the
other to the Sontheru Hemisphere. The next case, though not
so well known, is equally remarkable; it is that of the Ccnteti-
tise, a family of small insectivorous animals, which are wholly
confined to Madagascar and the large West ludian islands Cubiv
and Ilayti, the former containing five genera and the latter a
single genua with a species in each island. Here again we have
tho whole continent of Africa as well as the Atlantic Ocean sep-
arating allied genera. Two families of rat like animals, Octo-
dontidni and Echimyidse, are also divided by the Atlantic, Both
arc mainly South American, but the former has two genera in
North and East Africa, and the latter also two in South and
West Africa. Two other familiea of mammalia, thongh confined
to the Eaeteni Hemisphere, aro yet markedly discontinuous.
The Tragiilidai are small deer-like animals, known as chevrotains
or mousu-decr, abundant in India and the larger Malay islands,
and forming the genus Traguhts; while another genns, Hyo-
moschiis, is confined to West Afnea. The other family ia the
Simiidte or anthropoid apes, in which we have the gorilla and
chimpanzee confined to West and Central Africa, M'hile the
allied oranga are found only in tho islands of Sumatra and
Borneo, the two groups being separated by a greiiter space
chap.il] the elementary facts of distribution. 27
than the Echimyidae and other rodents of Africa and South
America.
Among birds and reptiles we have several families, which,
from being found only within the tropics of Asia, Africa, and
America, have been termed tropicopolitan groups. The Mega-
Isemidae, or barbets, are gayly colored fruit-eating birds, almost
equally abundant in tropical Asia and Africa, but less plentiful
in America, where they probably suffer from the competition
of the larger sized toucans. The genera of each country are
distinct, but all are closely allied, the family being a very nat-
ural one. The trogons form a family of very gorgeously col-
ored and remarkable insect-eating birds very abundant in trop-
ical America, less so in Asia, and with a single genus of two
species in Africa.
Among reptiles we have two families of snakes — the Den-
dropliidse, or tree-snakes, and the Dryiophidse, or green whip-
snakes — which are also found in the three tropical regions of
Asia, Africa, and America, but in these cases even some of the
genera are common to Asia and Africa, or to Africa and Amer-
ica. The lizards forming the small family I^pidosternidae are
divided between tropical Africa and South America, while
even the peculiarly American family of the iguanas is repre-
sented by two genera in Madagascar. Passing on to the Am-
phibians, the worm-like Cseciliadae are tropicopolitan, as are also
the toads of the family Phryniscidse. Insects also furnish some
analogous cases, three genera of Cicindelidse (Pogonostoraa, Cte-
nostoma, and Peridexia), showing a decided connection between
this family in South America and Madagascar ; while the beau-
tiful genus of diurnal moths, Urania, is confined to the same
two countries. A somewhat similar but better-known illustra-
tion is afforded by the two genera of ostriches, one confined to
Africa and Arabia, the other to the plains of temperate South
America.
General Features of Overlapping and Discontinuous Areas, —
These numerous examples of discontinuous genera and families
form an important section of the facts of animal dispei-sal which
any true theory must satisfactorily account for. In greater or
less prominence they are to be found all over the world, and in
28 ISLAND LIFE. [Part L
every group of animals, and they grade imperceptibly into
those eases of conterminous and overlapping areas which we
have seen to prevail in most extensive groups of species, and
w^hich are perhaps even more common in those large families
which consist of many closely allied genera. A suflScient proof
of the overlapping of generic areas is the occurrence of a num-
ber of genera of the same family together. Thus in France or
Italy about twenty genera of warblers (Sylviadae) are found,
and as each of the thirty-three genera of this family inhabiting
temperate Europe and Asia has a different area, a great number
must here overlap. So, in most parts of Africa at least, ten or
twelve genera of antelopes may be found, and in South Amer-
ica a large proportion of the genera of monkeys of the family
Cebidffi occur in many districts ; and still more is this the case
with the larger bird families, such as the tanagers, the tyrant
shrikes, or the tree-creepers, so that there is in all these exten-
sive families no genus whose area does not overlap that of many
others. Then among the modemtely extensive families we find
a few instances of one or two genera isolated from the rest, as
the spectacled bear, Tremarctos, found only in Chili, while the
remainder of the family extends from Europe and Asia over
North America to the mountains of Mexico, but no farther
south ; the Bovidse, or hollow-horned ruminants, which have a
few isolated genera in the Kocky Mountains and the islands of
Sumatra and Celebes ; and from these we pass on to the cases
of wide separation already given.
liestncted Areas of Families. — As families sometimes con-
sist of single genem and even single species, they often present
examples of very restricted range; but what is perhaps more
interesting are those cases in which a family contains numerous
species and sometimes even several genera, and yet is confined
to a narrow area. Such are the golden moles (Chrysochloridoe),
consisting of two genera and three species, confined to extra-
tropical South Africa; the hill-tits (Liotrichidie), a family of
eleven genera and thirty-five species almost wholly limited to
the Uimalayas, but with a few straggling species in the Malay
countries ; the Pteroptochidce, large wren-like birds, consisting
of eight genera and nineteen specioB, almost entirely confined
Chap. II.] THE ELEMENTARY FACTS OF DISTRIBUTION. 29
to temperate South America and the Andes ; and the birds-of-
paradise, consisting of nineteen or twenty genera and about
thirty-five species, almost all inhabitants of New Guinea and
the immediately surrounding islands, while a few, doubtfully
belonging to the family, extend to East Australia. Among
reptiles the most striking case of restriction is that of the rough-
tailed burrowing snakes (Uropeltidfle), the five genera and eigh-
teen species being strictly confined to Ceylon and the southern
parts of the Indian Peninsula.
The DiBtrihution of Orders, — When we pass to the larger
groups, termed orders, comprising several families, we find com-
paratively few cases of restriction and many of world-wide dis-
tribution; and the families of which they are composed are
strictly comparable to the genera of which families are com-
posed, inasmuch as they present examples of overlapping, or
conterminous, or isolated areas, though the latter are compara-
tively rare. Among mammalia the Insectivora offer the best
example of an order several of whose families inhabit areas
more or less isolated from the rest ; while the Marsupialia have
six families in Australia, and one, the opossums, far off in
America.
Perhaps, more important is the limitation of some entire
orders to certain well-defined portions of the globe. Thus the
Proboscidea, comprising the single family and genus of the ele-
phants, and the Hyracoidea, that of the Hyrax or Syrian cony,
are confined to parts of Africa and Asia; the Marsupials to
Australia and America ; and the Monotrcmata, the lowest of all
mammals — comprising the duck-billed Platypus and the spiny
Echidna — to Australia. Among birds the Struthiones, or ostrich
tribe, are almost confined to the three southern continents. South
America, Africa, and Australia ; and among Amphibia the tailed
Batrachia — the newts and salamander — are similarly restricted
to the Northern Hemisphere.
These various facts will receive their explanation in a future
chapter.
30 ISLAND LIFE. [Pabt 1.
CHAPTER III.
CLASSIFICATION OF THE FACTS OF DISTRIBUTION.— ZOOLOGICAL
REGIONS.
The Geographical Divisions of the Globe do not Correspond to Zoological Divisions.
— The Range of British Mammals as Indicating a Zoological Region.— Range of
East Asian and North African Mammals. — Tlie Range of British Birds. — Range
of East Asian Birds. — The Limits of the Pala>arctic Region. — Characteristic Feat>
ures of the Fal^arctic Region. — Definition and Characteristic Groups of the Ethi-
opian Region. — Of the Oriental Region. — Of the Australian liegion. — Of the Ne-
arctic Region. — Of the Neotropical Region. — Comparison of Zoological Regions
with the Geographical Divisions of the Globe.
Having now obtained some notion of how animals are dis-
persed over the earth's surface, whether as single species or as
collected in those groups termed genera, families, and orders, it
will be well, before proceeding further, to understand something
of the classification of the facts we have been considering, and
some of the simpler conclusions these facts lead to.
Wo have hitherto described the distribution of species and
groups of animals by means of the great geographical divisions
of the globe in common use ; but it will have been observed
that in hardly any case do these define the limits of anything
beyond species, and very seldom, or perhaps never, even those
accurately. Thus the term "Europe" will not give, with any
approach to accuracy, the range of any one genus of mammals
or birds, and perhaps not that of half-a-dozen species. Either
they range into Siberia, or Asia ^Minor, or Palestine, or North
Africa ; and this seems to be always the case when their area
of distribution occupies a largo portion of Europe. There are,
indeed, a few species limited to Central or Western or Southern
Europe, and these are almost the only cases in which we can
use the word for zoological pui'poses without having to add to
it some portion of another continent. Still less useful is the
Chap. III.] ZOOLOGICAL REGIONS. 31
term Asia for this purpose, since tliere is probably no single
animal or group confined to Asia which is not also more or less
nearly confined to the tropical or the temperate portion of it.
The only exception is perhaps the tiger, which may really be
called an Asiatic animal, as it occupies nearly two thirds of the
continent; but this is a unique example, while the cases in
which Asiatic animals and groups are strictly limited to a por-
tion of Asia, or extend also into Europe or into Africa or to the
Malay Islands, are exceedingly numerous. So, in Africa, very
few groups of animals range over the whole of it without going
beyond, either into Europe or Asia Minor or Arabia, while those
which are purely African are generally confined to the portion
south of the tropic of Cancer. Australia and America are terms
which better serve the purpose of the zoologist. The former
defines the limit of many important groups of animals; and the
same may be said of the latter, but the division into North and
South America introduces difficulties, for almost all the groups
especially characteristic of South America are found also beyond
the isthmus of Panama, in what is geographically part of the
northern continent.
It being thus clear that the old and popular divisions of the
globe are very inconvenient when used to describe the range of
animals, we are naturally led to ask whether any other division
can be made which will be more useful, and will serve to group
together a considerable number of the facts we have to deal
with. Such a division was made by Mr. P. L. Sclater more than
twenty years ago, and it has, with some slight modification, come
into pretty general use in this country, and to some extent also
on the Continent ; we shall therefore proceed to explain its nat-
ure and the principles on which it is established, as it will have
to be often referred to in future chapters of this work, and will
take the place of the old geographical divisions, whose extreme
inconvenience has already been pointed out. The primary
zoological divisions of the globe are called " regions," and we
will begin by ascertaining the limits of the region of which our
own country forms a part.
Tlie Range of British MammaU as Indicating a Zoological
Region. — We will first take our commonest wild mammalia and
32
ISLAND LIFE.
[Pabt I.
see how far they extend, and especially whether they are eon-
fined to Europe or range over parts of other continents :
1. Wild-cat..
2. Fox
3. Weasel...
4. Otter
r>. Badger...
C. Stag
7. Hedgehog
8. Mole
9. Squirrel . .
10. Dormouse
11. Water-rat.
12. Hare
13. liabbit. . . .
Europe
i(
t(
((
i(
it
4(
i(
t(
((
(t
North Africa
it
<t
t(
tt
t(
it
(t
t<
(t
North Africa
Siberia, Afghanistan.
Central Asia to Amoor.
it t( tt
Siberia.
Central Asia to A moor,
tt tt (t
tt tt (t
Central Asia.
Central Asia to Amoor.
Central Asia to Amoor.
West Siberia, Persia.
We thus see that out of thirteen of our commonest quadru-
peds only one is confined to Europe, while seven are found also
in Northern Africa and eleven range into Siberia, most of them
stretching quite across Asia to the valley of the Amoor on the
extreme eastern side of that continent. Two of the above-named
British species, the fox and weasel, are also inhabitants of the
New World, being as common in the northern parts of North
America as they are with us ; but with these exceptions the en-
tire range of our commoner species is given, and they clearly
show that all Northern Asia and Northern Africa must be added
to Europe in order to form the region which they collectively
inhabit. If now we go into Central Europe and take, for exam-
ple, the quadrupeds of Germany, we shall find that these too, al-
though much more numerous, are confined to the same limits,
except that some of the more arctic kinds, as already stated, ex-
tend into the colder regions of North America.
Range of East Asian and North African MammaU, — Let us
now pass to the other side of the great northern continent, and
examine the list of the quadrupeds of Amoorland, in the same
latitude as Germany. We find that there are forty-four terres-
trial species (omitting the bats, the seals, and other marine ani-
mals), and of these no less than twenty-six are identical with
European species, and twelve or thirteen more are closely allied
representatives, leaving only five or six which are peculiarly
Asiatic. We can hardly have a more convincing proof of the es-
sential oneness of the mammalia of Europe and Northern Asia.
Chap. III.] ZOOLOGICAL REGIONS. 33
In Northern Africa we do not find so many European species
(thongh even here they are very numerous), because a consider-
able number of West Asiatic and Desert forms occur. Having,
however, shown that Europe and Western Asia have ahnost
identical animals, we may treat all these as really European, and
we shall then be able to compare the quadrupeds of North Af-
rica with those of Europe and West Asia. Taking those of Al-
geria as the best known, we find that there are thirty-three spe-
cies identical with those of Europe and West Asia, while twenty-
four more, thongh distinct, are closely allied, belonging to the
same genera; thus making a total of fifty-seven of European
type. On the other hand, we have seven species which are either
identical with species of tropical Africa or allied to them, and
six more which are especially characteristic of the African and
Asiatic deserts, which form a kind of neutral zone between the
temperate and tropical regions. If now we consider that Algeria
and the adjacent countries bordering the Mediterranean form
part of Africa, while they are separated from Europe by a wide
sea, and are only connected with Asia by a narrow isthmus, we
cannot but feel surprised at the wonderful preponderance of the
European and West Asiatic elements in the mammalia which
inhabit the district.
The Range of British Birds. — As it is very important that
no doubt should exist as to the limits of the zoological region of
which Europe forms a part, we will now examine the birds, in
order to see how far they agree in their distribution with the
mammalia. Of late yeara great attention has been paid to the
distribution of European and Asiatic birds, many ornithologists
having travelled in North Africa, in Palestine, in Asia Minor, in
Persia, in Siberia, in Mongolia, and in China ; so that we are now
able to determine the exact ranges of many species in a manner
that would have been impossible a few years ago. These ranges
are given for all British species in the new edition of Yarrell's
"History of British Birds," now in coui*se of publication under
the editorship of Professor Newton, while those of all European
birds are given in still more detail in Mr. Dresser's beautiful
work on the birds of Europe just completed. In order to con-
fine our examination within reasonable limits, and at the same
3
34: ISLAND LIFE. [Part I.
time give it the interest attaching to familiar objects, we will
take the whole series of British Passeres, or perching birds, given
in Professor Newton's work (118 in number), and arrange them
in series according to the extent of their range. These include
not only the permanent residents and regular migrants to our
country, but also those which occasionally straggle here, so that
it really comprises a large proportion of all European birds.
I. British Birds which Extend to North Africa and Central or North-
east Asia.
1. Lanius collutio *. . . . . Red-backed Shrike (also all Africa)
2. Oriolus yalbula Golden Oriole (also all Africa).
3. Turdus musicus Song-thrush.
4. ** iliacus Uedwing.
r». ** pilaris Fieldfare.
G. Monticola saxatilis Blue-rock Tlirush.
7. Ruticilla Suecica Blue-throat (also India in winter).
8. Saricola rubicola Stone-chat (also India in winter).
9. ** ananlhe Wheat-ear (also North America).
10. Acrocephalus arundinaceus Great Keed-warblcr.
I I . Sylvia curruca Lesser White-throat.
1 2. Parus major Great Titmouse.
] 3. Motacilla sulphurea Gray Wagtail (also China and Malaya).
U. " Rait Yellow Wagtail.
1 5. Anthus trivialis Tree-pipit.
16. * * spiloletta Water-pipit.
17. * ' campestris Tawny Pipit.
18. Ahuda arvensls Skylark.
19. ** cristata Crested Lark.
20. Emheriza schctniclus Heed-bunting.
21. ' * citrinella Yellow-hammer.
22. Fringilla montifringilla Brambling.
23. Passer montanus Tree-sparrow (also South Asia).
24. * * domesticus House-sparrow.
2'). Cor.cothraustes vulgaris Hawfinch.
20. Cardueiis spinus. Siskin (also China).
27. Loxia curvirostra Crossbill.
28. Sturnus vulgaris Starling.
29. Pi/rrhocorax graculus Chough.
30. Corvus corone Crow.
31 . Hirundo rustica Swallow (all Africa and Asia).
82. Cotyle riparia Sand-martin (also India and North America).
2. British Birds which Range to Central or Northeast Asia.
1 . Lanius excuhitor Great Grnv Shrike.
2. Turdus varius White's Thrush (also to Japan).
Chap. III.] ZOOLOGICAL llEGIONS. 35
3. Turdus atrigularis* Black-throated Thrush.
4. Acrocephalus noevius Grasshopper-warbler.
i>. Phylloscopus superdliasus Yellow-browed Warbler.
C. Certhia familiaris Ti*e©-creeper.
7. Parus cceruleus Blue Titmouse.
8. " ater. Coal Titmouse.
9. ** palustris. Marsh Titmouse.
10. Acreduia caudata Long-tailed Titmouse.
1 1. Ampelis garrulus Waxwing.
1 2. Anthus Richardi Richard's Pipit
13. Alauda alpestris, Shore- lark (also North America).
14. Plectrophanes nivalis Snow-buntitig (also North America).
15. * ' Lapponicus, Jjapland Bunting.
IG. Emheriza rustica Kustic Bunting (also China).
17. *' pusilia Little Bunting.
18. Linota linctria Mealy BedpoU (also North America).
19. Pyrrhula Erythrina Scarlet Grossbeak (also North India, China).
20. '* enucleatar Pine Grossbeak (also North America).
21 . Loxia bifasciata Two-barred Crossbill.
22. Pastor roseus. Kose-colored Starling (also India).
23. Corvus corax Raven (also North America).
24. Pica rustica Magpie.
25. Nucifraga caryocatactes Nut-cracker.
3. British Birds Ranging into North Africa and West Asia.
1. Latdus minor Lesser Gray Shrike.
2. ** auriculatus Wood-chat (also tropical Africa).
3. Muacicapa grisola Spotted Flycatcher (also E. and S. Africa).
4. " atricapilla Pied Flycatcher (also Central Africa).
r», Tttrdus viscivorus. Mistletoe Thrush (North India in winter).
6. ** merula Blackbird.
7. *' torquatus Ring-ouzel.
8. Accentor modularis Hedge-sparrow.
9. Krithticus rubectda Redbreast.
] 0. Daulias luscima Nightingale.
] I . Ruticilla phanicwrus Redstart.
12. ** Tithys Black Redstai-t
] 3. Saxicola rubetra Whinchat.
1 4. ASdon galactodes Rufous Warbler.
] .*». Acrocephalus streperus Reed- warbler.
16. ** schcenobenus Sedge- warbler.
17. MeHzopkilus undatus Dartford Warbler.
18. Sylvia ru/a Greater White-throat.
19. * ' saliearia Garden-warbler.
20. *' atricapilla Blackcap.
21. ** orphea Orphean Warbler.
22. Phylloscopus sibilatrix Wood-wren,
36 ISLAND LIFE. [Part L
23. Phylloscopus trochiius Willow-wren.
24. * ' collyhita Chiffchaff
25. ReguluB cristatus Golden-crested Wren.
26. * ' ignicapillta Fire-ci-ested Wren.
27. Troglodytes parvulus , Wren.
28. Sitta cctsia Nutlmteh.
29. Motacilla alba White Wagtail (also West Africa).
80. ** flava Blue-headed Wagtail.
8 1 . Anthus praterms, Meadow-pipit.
82. Alauda arhorea Woodlark.
83. Calandrella hrachydactyla Short-toed Lark.
84. Emheriza milaria .*.... Common Buftting.
85. " cirlus Cirl Banting.
86. ** horiulana Ortolan.
37. Fringilla Calebs Chaffinch.
88. Coccothraustes chloris, Greenfinch.
89. Serinus hortulanus, Serin.
40. Carduelis elegans Goldfinch.
41. Linota cannabina Linnet.
42. Corvus monedula Jackdaw.
43. Chelidon urbica House-maitin.
4. British Birds Ranging to North Africa.
1. Uypolais icterina Icterine Warbler.
2. Acrocephalus aquaticus Aquatic Warbler.
8. ** luscinioides Savi's Warbler.
4. Motacilla lugubris *. Pied Wagtail.
5. Pyrrhula Europata Bullfinch.
C. Gatrulus glandaHus Jay.
5. British Birds Hanging to West Asia only.
1 . Muscicapa parva Ked-breasted Flycatcher (to Northwest India).
2. Panttrus biarmicus Bearded Titmouse.
8. Melanocorypha Sibirica White-winged Lark.
4. Euspiza metanocephala Blnck-headed Bunting.
5. Linota JlavirostHs Twite.
C. Corvus frugilegus Rook.
C. British Birds Confined to Europe.
1. Cinclus aquaticus Dipper.
2. Accentor collaris Alpine Accentor.
8. Parus cristatus Crested Titmouse.
4. Anthus obscurus Rock-pipit.
5. Linota rufescens. Lesser Redpoll.
G. Loxia pityopsittacus Parrot Crossbill.
Chap. III.] ZOOLOGICAL REGIONS. 37
We find that out of a total of 118 British Passeres there arc :
32 species which range to North Africa and Central or East Asia.
25 " *' »» " Central or East Asio, but not to North Afdca.
43 ** ** ** " North Afnca and Western Asia.
G *' " ** " North Africa, but not at all into Asia.
6 ** ** ** *' West Asia, but not to North Africa.
G ^* *^ do not range oat of Europe.
These figures agree essentially with those furnished by the
mammalia, and complete the demonstratioa that all the temper-
ate portions of Asia and North Africa must be added to Europe
to form a natural zoological division of the earth. We must also
note how comparatively few of these overpass the limits thus
indicated ; only seven species extending their range occasionally
into tropical or South Africa, eight into some parts of tropical
Asia, and six into arctic or temperate North America.
Range of East Asian Birds, — To complete the evidence, we
only require to know that the East Asiatic birds are as much
like those of Europe as we have already shown to be the case
when we take the point of departure from our end of the conti-
nent. This does not follow necessarily, because it is possible that
a totally distinct North Asiatic fauna might there prevail ; and,
although our birds go eastward to the remotest parts of Asia,
their birds might not come westward to Europe. The birds of
Eastern Siberia have been carefully studied by Hussian natural-
ists, and afford us the means of making the required comparison.
There are 151 species belonging to the orders Passeres and Pica-
rise (the perching and climbing birds), and of these no less than
77, or more than half, are absolutely identical with European
species ; 63 are peculiar to North Asia, but all except five or six
of these are allied to European forms; the remaining 11 spe-
cies are migrants from Southeastern Asia. The resemblance is
therefore equally close whichever extremity of the Euro- Asiatic
continent we take as our starting-point, and is equally remarkable
in birds as in mammalia. We have now only to determine the
limits of this our first zoological region, which has been termed
the " Palsearctic " by Mr. Sclater, meaning the " northern old-
world " region — a name now well known to naturalists.
The Limits of the Palwarctic Begion. — The boundaries of
38 ISLAND LIFE. [Pabt I.
this region, as nearly as they can be ascertained, are shown on
our general map at the beginning of this chapter, but it will be
evident on consideration that, except in a few places, its limits
can only be approximately defined. On the north, east, and
west it extends to the ocean, and inclades a number of islands
whose peculiarities will be pointed out in a subsequent chapter ;
so that the southern boundary alone remains ; but as this runs
across the entire continent from the Atlantic to the Pacific
Ocean, often traversing little-known regions, we may perhaps
never be able to determine it accurately, even if it admits of
such determination. In drawing the boundary-line across Af-
rica we meet with our first diflSculty. The Euro-Asiatic ani-
mals undoubtedly extend to the northern borders of the Sahara,
while those of tropical Africa come up to its southern margin,
the desert itself forming a kind of dry sea between them. Some
of the species on either side penetrate and even cross the desert,
but it is impossible to balance these with any accuracy, and it
has therefore been thought best, as a mere matter of conven-
ience, to consider the geographical line of the tropic of Cancer
to form the boundarv. We are thus enabled to define the Pa-
Isearctic region as including all north temperate Africa ; and a
similar intermingling of animal types occurring in Arabia, the
same boundary-line is continued to the southern shore of the
Pereian Gulf. Persia and Afghanistan undoubtedly belong to
the Palsearctic region, and Beloochistan should probably go with
these. The boundary in the northwestern part of India is again
difficult to determine, but it cannot be far one way or the other
from the river Indus as far up as Attock, opposite the mouth of
the Cabool Eiver. Here it will bend to the southeast, passing
a little south of Cashmere, and along the southern slopes of the
Himalayas into East Thibet and China, at heights varying from
9000 to 11,000 feet, according to soil, aspect, and shelter. It
may, perhaps, be defined as extending to the upper belt of for-
ests as far as coniferous trees prevail ; but the temperate and
tropical faunas are here so intermingled that to draw any exact
parting-line is impossible. The two faunas are, however, very
distinct. In and above the pine woods there are abundance of
warblera of northern genera, with wrens, numerous titmice, and
CiiAP.ITL] ZOOLOGICAL REGIONS. 39
a great variety of buntings, grossbeaks, bullfinches, and rosefincli-
es, all more or less nearly allied to the birds of Europe and
Northern Asia ; while a little lower down we meet with a host
of peculiar birds allied to those of tropical Asia and the Malay
Islands, but often of distinct genera. There can be no doubt,
therefore, of the existence here of a pretty sharp line of demar-
cation between the temperate and tropical faunas, though this
line will be so irregular, owing to the complex system of valleys
and ridges, that in our present ignorance of much of the coun-
try it cannot be marked in detail on any map.
Fartlier east in China it is still more difficult to determine
the limits of the region, owing to the great intermixture of mi-
grating birds ; tropical forms passing northward in summer as
far as the Amoor Kiver, while the northern forms visit every
part of China in winter. From what we know, however, of the
distribution of some of the more typical northern and southern
species, we are able to fix the limits of the Palsearctic region a
little south of Shanghai on the coast. Several tropical genera
come as far as Ningpo or even Shanghai, but rarely beyond ;
while in Formosa and Amoy tropical forms predominate. Such
decidedly northern forms as bullfinches and hawfinches are
found at Shanghai ; hence we may commence the boundarj--
line on the coast between Shanghai and Ningpo, but inland it
probably bends a little southward, and then northward to the
mountains and valleys of West China and East Thibet in about
32° north latitude; where, at Moupin,a French missionary, Pere
David, made extensive collections showing this district to be at
the junction of the tropical and temperate faunas. Japan, as a
whole, is decidedly Palaearctic, although its extreme southern
portion, owing to its mild insular climate and evergreen vegeta-
tion, gives shelter to a number of tropical forms.
Characteristic Features of the Palmarctic Region. — Having
thus demonstrated the unity of the Palsearctic region by tracing
out the distribution of a large proportion of its mammalia and
birds, it only remains to show how far it is ch»iracterized by pe-
culiar groups such as genera and families, and to say a few words
on the lower forms of life which prevail in it.
Taking first the mammalia, we find this region is distinguished
40 ISLAND LIFE. [Part L
by its possession of tlie entire family of Talpidse, or moles, con-
sisting of eight genera and sixteen species, all of which are con-
lined to it except one which is found in Northwest America,
and two which extend to Assam and Formosa. Among carniv-
orous animals the lynxes (nine species) and the badgers (two spe-
cies) are peculiar to it in the Old World, while in the New the
lynxes are found only in the colder regions of North America.
It has six peculiar genera (with seven species) of deer; seven
peculiar genera of Bovidae, chiefly antelopes ; while the entire
group of goats and sheep, comprising twenty-two species, is al-
most confined to it, one species only occurring in the Rocky
Mountains of North America and another in the Neilgherries
of Southern India. Among the rodents there are nine genera
with twenty-seven species wholly confined to it, while several
others, as the voles, tlie dormice, and the pikas, have only a few
species elsewhere.
In birds there are a large number of peculiar genera, of which
we need only mention a few of the more important, as the grass-
hopper-warblers (Locustella) with seven species, the Accentors
with twelve species, and about a dozen other genera of warblere,
including the robins ; the bearded titmouse and several allied
genera; the long-tailed titmice forming the genus Acredula;
the magpies, choughs, and nut-crackers ; a host of finches, among
which the bullfinches (Pyrrhula) and the buntings (Emberiza)
are the most important. The true pheasants (Phasianus) are
wholly Palflearctic, except one species in Formosa, as are several
genera of wading birds. Though the reptiles of cold countries
are few as compared with those of the tropics, the Palaearctic
region in its warmer portions has a considerable number, and
among these are many which are peculiar to it. Such are two
genera of snakes, seven of lizards, eight of frogs and toads, and
eight of newts and salamanders; while of fresh -water fishes
there are about twenty peculiar genera. Among insects we
may mention the elegant Apollo butterflies of the Alps as form-
ing a peculiar genus (Parnassius), only found elsewhere in the
Kocky Mountains of North America; while the beautiful genus
Thais of the South of Europe and Sericinus of North China are
equally remarkable. Among other insects we can now only refer
Chap.IIL] zoological REGIONS. 41
to the great family of Carabidse, or predaceous ground beetles,
which are immensely numerous in this region, there being
about fifty peculiar genera; while the large and handsome ge-
nus Carabus, with its allies Procerus and Procrustes, containing
nearly three hundred species, is almost wholly confined to this
region, and would alone serve to distinguish it zoologically from
all other parts of the globe.
Having given so full an exposition of the facts which deter-
mine the extent and boundaries of the Palsearctic region, thei*e
is less need of entering into much detail as regards the other
regions of the Eastern Hemisphere; their boundaries being
easily defined, while their forms of animal life are well marked
and strongly contrasted.
Definition and Characteristic Groups of the Ethiopian He-
ffion, — The Ethiopian region consists of all tropical and South
Africa, to wliich is appended the large island of Madagascar, and
the Mascai'ene Islands to the east and north of it, though these
differ materially from the continent, and will have to be dis-
cussed in a sepai-ate chapter. For the present, then, we will
take Africa south of the tropic of Cancer, and consider how
far its animals are distinct from those of the Palsearctic re-
gion.
Taking first the mammalia, we find the following remarkable
animals at once separating it from the Palaearctic and every oth-
er region. The gorilla and chimpanzee, the baboons, numerous
lemurs, the lion, the spotted hyena, the aard-wolf and hyena-
dog, zebras, the hippopotamus, giraffe, and more than seventy
peculiar antelopes. Here we have a wonderful collection of
large and peculiar quadrupeds; but the Ethiopian region is also
characterized by the absence of others which are not only abun-
dant in the Patearctic region, but in many tropical regions as
well. The most remarkable of these deficiencies are the bears,
the deer, and wild oxen, all of which abound in the tropical
parts of Asia, while bears and deer extend into both North and
South America. Besides the large and conspicuous animals
mentioned above, Africa possesses a number of completely iso-
lated groups; such are the potamogale, a curious otter-like wa-
42 ISLAND LIFE. [Pakt L
ter-sbrew, discovered by Du Chaillu in West Africa, so distinct
as to constitute a new family, Potamogalidae ; the golden moles,
also forming a peculiar family, Chrysochloridae ; as do the ele-
phant-shrews, MacroscelididsB ; the singular aard-varks, or earth-
pigs, forming a peculiar family of Edentata, called Orycteropo-
didse; while there are numerous peculiar genera of monkeys,
swine, civets, and rodents.
Among birds the most conspicuous and remarkable are the
great-billed vulture-crows (Corvultnr), the long-tailed whydah
finches (Vidua), the curious ox-peckers (Buphaga), the splendid
metallic starlings (Lamprocolius), the handsome plantain-eaters
(Musophaga), the ground -hornbills (Bucorvus), the numerous
guinea-fowls belonging to four distinct genera, the serpent-eat-
ing secretary-bird (Serpentarius), the huge boat- billed heron
(Balaeniceps), and the true ostriches. Besides these there are
three quite peculiar African families, the Musophagidse, or plan-
tain-eatere, including the elegant crested touracos; the curious
little finch-like colies (Coliidse), and the Irrisoridae, insect-eating
birds allied to the hoopoes, but with glossy metallic plumage
and arboreal habits.
In reptiles, fishes, insects, and land shells, Africa is very rich,
and possesses an immense number of peculiar forms. These are
not suflSciently known to require notice in a work of this char-
acter, but we may mention a few as mere illustrations ; the puff-
adders, the most hideous of poisonous snakes; the chameleons,
the most remarkable of lizards ; the goliath-beetles, the largest
and handsomest of the Cetoniidce ; and some of the Achatinse,
which are tlie largest of all known land shells.
Definition and Characteristic Groups of the Oriental Region,
— The Oriental region comprises all Asia south of the Palae-
arctic limits, and along with this the Malay Islands as far as the
Philippines, Borneo, and Java. It was called the Indian region
by Mr. Sclater ; but this term has been objected to because the
Indo-Chinese and Malayan districts are the richest and most
characteristic, while the peninsula of India is the poorest por-
tion of it. The name " Oriental" has therefore been adopted in
my work on "The Geographical Distribution of Animals" as
preferable to either Malayan or Indo-Australiun, both of which
Chap. III.] ZOOLOGICAL REGIONS. 43
have been proposed, but are objectionable, as being already in
use in a different sense.
The great features of the Oriental region are the long-armed
apes, the orang-outangs, the tiger, the sun-bears and honey-bears,
the tapir, the chevrotains or mouse-deer, and the Indian ele-
phant. Its most conspicuous birds are the immense number and
variety of babbling-thrushes (Timaliidflp), its beautiful little hill-
tits (Liotrichidse), its green bulbuls (Phyllornithidee), its many
varieties of the crow family, its beautiful gapers and pittas
adorned with the most delicate colors, its great variety of horn-
bills, and its magnificent Phasianidae, comprising the peacocks,
argns-pheasants, fire-backed pheasants, and jungle-fowl. Many
of these are, it is true, absent from the peninsula of Hindostan,
but suflScient remain there to ally it with the other parts of the
region.
Among the remarkable but less conspicuous forms of mam-
malia which are peculiar to this region are, monkeys of the
genus Presbyter, extending to every part of it ; lemurs of three
peculiar genera — ^Nycticebus and Loris (slow lemurs) and Tar-
sius (spectre lemurs); the flying lemur (Galeopithecus), now
classed as a peculiar family of Insectivora and found only in the
Malay Islands ; the family of the Tupaias, or squirrel-shrews,
curious little arboreal Insectivora somewhat resembling squir-
rels ; no less than twelve peculiar genera of the civet family,
three peculiar antelopes, five species of rhinoceros, and the
round-tailed flying squirrels forming the genus Pteromys.
Of the peculiar groups of birds we can only mention a few.
The curious little tailor -birds, of the genus Orthotomus, are
found over the whole region, and almost alone serve to charac-
terize it, as do the fine laughing-thrushes, forming the genus
Garrnlax ; while the beautiful grass-green fruit-thrushes (Phyl-
lornis), and the brilliant little minivets (Pericrocotns), are almost
equally universal. Woodpeckers are abundant, belonging to a
dozen peculiar genera ; while gaudy barbets and strange forms
of cuckoos and hornbills are also to be met with everywhere.
Among game birds, the only genus, that is universally distrib-
uted, and which may be said to characterize the region, is Qal-
Ins, comprising the true jungle-fowl, one of which, GdUvs Ban-
ISLAND LIFE.
iVxKV I
kiva, is found froiii tlio Iliinalayae and Central India to Ma-
lacca, Java, and even eastward to Timor, and is the undoubted
origiu of almost all our domestic poultry. Southern India and
Ceylon each possess distinct species of jungle-fowl, and a third
very Iiaiidsoiiio green bird {Gallus wtieus) inhabits Java.
Iteptiles arc as abundant as in Africa, but they present no
wcll-kiiown groups whieh cau be considered as specially charac-
teristic. Among insects we may notice the magnificent golden
iiiid green Papilionidie of various genera as being unequalled in
the world; while the great Atlas moth is probably the most
gigantic of Lepidopteru, being sometimes ten inches across the
wings, which are also very broad. Among the beetles the
Btrange fiat-bodied Malayan mormolyce is tlio largest of all the
Carabidte, while the catoxautha is equally a giant among the
Bnprestidie. On the whole, the insects of this region probably
surpass those of any other part of the world, except South
America, in size, variety, and beanty.
Z>>^nition and CAara-cteristii! Groups of the Australian He-
ffitMi. — The Australian region is so well marked off from the
Oriental, as well as from all other parts of the world, by zoologi-
cal peculiarities that we need not take up much time in describ-
ing it. especially as some of its component islands will como
under review at a subsequent stage of our work. Its most im-
portant portions are Australia and New Guinea, but it also in-
cludes all the Malayan and Pacific Islands to the cast of Borneo,
Java, and Bali, the Oriental region terminating with the sub-
marine bank on which those islands are situated. Tijc island of
Celubea is inclnded in this region from a balance of considera-
tions, but it almost equally well belong to the Oriental, and
must be left out of the account in our general sketch of the zoo-
logical features of the Australian region.
The great feature of the Australian region is the almost total
absence of all the forms of mammalia wliicli abound ia the rest
of the world, their place being supplied by a great variety of
marsupials. In Australia and New Guinea there are no Insec-
tivora, Oarnivora, nor Ungulata, while even the rodents are only
represented by a few small rats and mice. In the Pacific Islands
nnimmals are altogether absent (except perhaps in \ew Ze.iland),
Chap. III.] ZOOLOGICAL REGIONS. 45
but in the Moluccas and other islands bordering on the Oriental
region the higher mammals are represented by a few deer, civets,
and pigs, though it is doubtful whether the two former may not
have been introduced by man, as was almost certainly the case
with the semi-domesticated dingo of Australia. These peculi-
arities in the mammalia are so great that every naturalist agrees
that Australia must be made a separate region, the only differ-
ence of opinion being as to its extent, some thinking that New
Zealand should form another separate region ; but this question
need not now delay us.
In birds Australia is by no means so isolated from the rest of
the world, as it contains great numbers of warblers, thrushes, fly-
catchers, shrikes, crows, and other familiar types of the Eastern
Hemisphere ; yet a considerable number of the most character-
istic Oriental families are absent. Thus there are no vultures,
woodpeckers, pheasants, bulbuls, or barbets in the Australian
region ; and the absence of these is almost as marked a feature
as that of cats, deer, or monkeys among mammalia. The most
conspicuous and characteristic birds of the Australian region
are, the piping-crows ; the honey-suckers (Meliphagidae), a family
quite peculiar to the region ; the lyre-birds ; the great terrestrial
kingfishers (Dacelo); the great goat-suckers, called more-porks in
Australia, and forming the genus Podargus ; the wonderful
abundance of parrots, including such remarkable forms as the
white and the black cockatoos, and the gorgeously colored brush-
tongued lories ; the almost equal abundance of fine pigeons more
gayly colored than any others on the globe ; the strange brush-
turkeys and mound-builders, the only birds that never sit upon
their eggs, but allow them to be hatched, reptile-like, by the
heat of the sand or of fermenting vegetable matter; and, lastlj-,
the emus and cassowaries, in which the wings are far more rudi-
mentary than in the ostriches of Africa and South America.
New Guinea and the surrounding islands are remarkable for
their tree-kangaroos, their birds-of-paradise, their raquet-tailed
kingfishers, their great crown-pigeons, their crimson lories, and
many other remarkable birds. This brief outline being suffi-
cient to show the distinctness and isolation of the Australian
region, we will now pass to the consideration of the Western
Hemisphere.
[Pawl
Dejinition and Vharacterintio Groups of (he A'earctic Sfgion.
— The Neavctic region coinpi-ises all temiierate and arctic North
America, including Greenland, t!ie only doubt Iviing 8S to its
BontLern boundiiry, many nortliem types iieiietratiug into the
tropical zone by means of the bigliland& lutd volcanic peaks of
Mexico and Guatemala, while a few which are characteristic of
the tropica extend northward into Texas nnd California. There
IB, liowever, considerable evidence showing that on the east
coast the Rio Grande del Norte, and ou the west a point nearly
opposite Capo St. Lucas, form the most natural boundary; but
instead of being drawn straight across the line bends to the
southeast as Boon as it rises on the flanks of tlie table-land, f orm<
ing a deep loop which extends some distance beyond the city
of Mexico, and perhaps ought to be continued along the higher
ridges of Guatemala.
The Nearctic region is so similar to the Paliearetio in posi-
tion nnd climate, and the two so closely approach each other at
Behring Strait, that we cannot wonder at there being a certain
amount of similarity between them — a similarity whith some
natui'olists have so far overestimated as to think that the two
regions ought to be united. Let us therefore carefully examine
the special zoological features of this region, and see how far it
resembles, and how far differs from, the Palsearctic.
At first sight the niauiinnlia of North America do not seem
to differ much from those of Europe or Northern Asia. There
are cats, lynxes, wolves and foxes, weasels, beara, elk and deer,
voles, beavci'6, squirrels, marmots, and bares, all very similar to
those of the Eastern Hemisphere, and several Iiardly distinguish-
able. Even tlio bison or "bnffalo" of the prairies, once so
abundant and characteristic, is a close ally of the now almost
extinct "aurochs" of Litlinania. Here, then, we undoubtedly
find a very close resemblance between the two regions; and if
this wore all, we should have great difficulty in separating them.
But along wilh these we tind another set of mamnmls, not quite
60 eonspicuous, but nevertheless very important, Wt- have, first,
three peculiar genera of moles, one of which, the star-nosed
mole, is a most extraordinary creature, quite unlike anything
else. Then there are three genera of the weasel family, inchid-
Chap. III.] ZOOLOGICAL REGIONS. 47
ing the well-known skunk (Mephitis), all quite different from
Eastern forms. Then we come to a peculiar family of carniv-
ora, the raccoons, very distinct from anything in Europe or
Asia ; and in the Eocky Mountains we lind the prong-horn an-
telope (Antilocapra) and the mountain - goat of the trappere
(Aplocerus), both peculiar genera. Coming to the rodents, we
find that the mice of America differ in some dental peculiarities
from those of the rest of the world, and thus form several dis-
tinct genera ; the jumping-mouse (Xapus) is a peculiar form of
the jerboa family, and then we come to the pouched rats, Ge-
omyidse, a very curious family, consisting of four genera and
nineteen species, peculiar to North America, though not con-
fined to the Nearctic region. The prairie-dogs (Cynomys), the
tree - porcupine (Erethizon), the curious sewellel (Haploodon),
and the opossum (Didelphys) complete the list of peculiar mam-
malia which distinguish the northern region of the New World
from that of the Old. We must add to these peculiarities some
remarkable deficiencies. The Nearctic region has no hedge-
hogs, nor wild -pigs, nor dormice, and only one wild -sheep in
the Kocky Mountains, as against twenty species of sheep and
goats in the Palsearctic region.
In birds also the similarities to our own familiar songsters
first strike us, though the differences are perhaps really greater
than in the quadrupeds. We see thmshes and wrens, tits and
finches, and what seem to be warblers and flycatchci*s and star-
lings in abundance; but a closer examination shows the orni-
thologist that what he took for the latter are really quite dis-
tinct, and that there is not a single true flycatcher of the family
Muscicapidse, or a single starling of the family Sturnidae, in the
whole continent ; while there are very few tnie warblere (Syl-
viidae), their place being taken by the very distinct families
Mniotiitidie, or wood-warblens, and Vireonida^, or greenlets. In
like manner the flycatchers of America belong to the totally
distinct family of tyrant-birds, Tymnnidse, and those that look
like starlings to the hang-nests, Icteridse; and these four pecul-
iar families comprise more than a hundred species, and give a
special character to the ornithology of the country. Add to
these such peculiar birds as the mocking-thrushes (Mimus), the
iS
ISLAND LIFE.
[Pa
blue jays (Cyanoeitta), tlie tanagers, the peculiar genera of cuck-
oos (Coccygufl and Crotophaga), the humming-birds, the wild-
tni-kej-s (Ueleagris), and the turkey-buzzards (Cathartes), and we
see that if there is any doubt as to the mammals of North Amer-
ica being sufficiently distinct to justify the creation of a sepa-
rate region, the evidence of the birds would nlono settle the
question.
The reptiles, and some othere of the lower animals, add still
more to this weight of evidence. The true rattlesnakes are
highly characteristic, and among the lizards are several genera
of the peculiar American family the IguanidiE. Nowhere in
the world are the tailed batrachJans so largely developed as in
this region, the Sirens and the Ainpliiumidfe forming two pe-
culiar families; wliilo there are nine peculiar genera of salaman-
ders, and two others allied respectively to tlic Proteus of Europe
and the Sieboldia, or giant salamander, of Japan. There are
about twenty-nine peculiar genera of fresh-water fishes; while
the fresh-water mollnsks are more numerous than in any other
region, more than thirteen hundred species and varieties having
been described.
Combining the evidence derived from all these classes of ani-
mals, we find the Nearctic region to be exceedingly well char-
acterized, and to be amply distinct from the Paltearctic. The
few species that are common to the two are almost all arctic, or
at least northern, types, and may be compared with those desert
forms which occuiiy tlie debatable ground between the Paliearc-
tic. Ethiopian, and Oriental regions. If, however, we compare
the number of species which are common to tlie Neai-ctic and
Paltearctic regions with the number common to the western and
eastern extremities of the latter region, we shall find a wonder-
ful difference between the two eases; and if we further call to
mind the number of important groups characteristic of the one
region but absent from the other, we shall be obliged to admit
that the relation that undoubtedly exists between the faunas of
North America and Europe is of a very distinct nature from
that which connects together Western Europe and Nortbeastcm
Asia in the bonds of zoological nnitj'.
Definition ami Charact^rititic Groups of the Neotropical lie-
Chap. III.] ZOOLOGICAL REGIONS. 49
gion. — The Neotropical region requires very little definition,
since it comprises the whole of America south of the Nearctic
region, with the addition of the Antilles or West Indian Islands.
Its zoological peculiarities are almost as marked as those of Aus-
tralia, which, however, it far exceeds in the extreme richness and
variety of all its forms of life. To show how distinct it is from
all the other regions of the globe, we need only enumerate some
of the best known and more conspicuous of the animal forms
which are peculiar to it. Such are, among mammalia, the pre-
hensile-tailed monkeys and the marmosets, the blood-sucking
bats, the coati-mundis, the peccaries, the llamas and alpacas, the
chinchillas, the agoutis, the sloths, the armadillos, and the ant-
eaters — a series of types more varied, and more distinct from
those of the rest of the world, than any other continent can boast
of. Among birds we have the charming sugar-birds, forming
the family Cosrebidse, the immense and wonderfully varied
group of tanagers, the exquisite little manakins, and tho gor-
geously colored chatterers ; the host of tree-creepers of tho fam-
ily Dendrocolaptidae, the wonderful toucans, the puff-birds, jaca-
mars, todies, and motmots; the marvellous assemblage of four
hundred distinct kinds of humming-birds, the gorgeous macaws,
the curassows, the trumpeters, and the sun-bitterns. Here again
there is no other continent or region that can produce such an
assemblage of remarkable and perfectly distinct groups of birds ;
and no less wonderful is its richness in species, since these fully
equal, if they do not surpass, those of tho two great tropical re-
gions of the Eastern Hemisphere (the Ethiopian and the Ori-
ental) combined.
As an additional indication of the distinctness and isolation
of the Neotropical region from all others, and especially from
the whole Eastern Hemisphere, wo must say something of the
otherwise widely distributed groups which are absent. Among
mammalia we have first the order Insectivora, entirely absent
from South America, though a few species are found in Central
America and the West Indies ; the Viverridae, or civet family, are
wholly wanting, as is every form of §heep, oxen, or antelopes;
while the swine, the elephants, and the rhinoceroses of the Old
World are represented by the diminutive peccaries and tapirs.
4
50 ISLAND LIFE. [Pabt L
Among birds wc have to notice the absence of tits, true fly-
catchei^s, shrikes, sun-birds, starlings, larks (except a solitary spe-
cies in the Andes), rollers, bee-eaters, and pheasants; while war-
blers are very scarce, and the almost cosmopolitan wagtails are
represented by a single species of pipit.
We must also notice the preponderance of low or archaic
types among the animals of South America. Edentates, marsu-
pials, and rodents form the majority of the terrestrial mammalia;
while such higher groups as tlie carnivora and Iioofed animals
are exceedingly deficient. Among birds a low type of Passeres,
characterized by the absence of the singing-muscles, is excessive-
ly prevalent, tlie enormous groups of the ant-thrushes, tyrants,
tree-creepers, manakins, and chatterers belonging to it. The
Picariae (a lower group) also prevail to a far greater extent than
in any other regions, both in variety of forms and number of
species; and the chief representatives of the gallinaceous birds
— the curassows and tinamous — are believed to be allied, the for-
mer to the brush-turkeys of Australia, the latter (very remotely)
to the ostriches, two of the least-developed types of birds.
Wliether, therefore, we consider its richness in peculiar forms
of animal life, its enormous variety of species, its numerous de-
ficiencies as compared with other parts of the world, or the prev-
alence of a low type of organization among its higher animals,
the Neotropical region stands out as undoubtedly the most re-
markable of the great zoological divisions of the earth.
In reptiles, amphibia, fresh-water fishes, and insects, this region
is equally peculiar, but we need not refer to these here, our only
object now being to establish by a suflicient number of well-
known and easily remembered examples tlie distinctness of each
region from all othere, and its unity as a wliole. The former has
now been sufficiently demonstrated, but it may be well to say a
few words as to the latter point.
The only outlying portions of the region about which there
can be any doubt are. Central America, or that part of the region
north of the Isthmus of Panama, the Antilles, or West Indian
Islands, and the temperate portion of South America, including
Chili and Patagonia.
In Central America, and especially in Mexico, we have an in-
CHAP.m.] ZOOLOGICAL REGIONS. 51
terinixture of South American and North American animals,
but the former undoubtedly predominate, and a large proportion
of the peculiar Neotropical groups extend as far as Costa Rica.
Even in Guatemala and Mexico we have howling and spider
monkeys, coati-mundis, tapirs, and armadillos ; while chatterers,
manakins, ant-thrushes, and other peculiarly Neotropical groups
of birds are abundant. There is therefore no doubt as to Mexico
forming part of this region, although it is comparatively poor,
and exhibits the intermingling of temperate and tropical forms.
The West Indies are less clearly Neotropical, their poverty in
mammals as well as in most other groups being extreme, while
great numbers of North American birds migrate there in winter.
The resident birds, however, comprise trogons, sugar-birds, chat-
terers, with many humming-birds and parrots, representing eigh-
teen peculiar Neotropical genera — a fact which decides the re-
gion to which the islands belong.
South temperate America is also very poor as compared with
the tropical parts of the region, and its insects contain a consid-
erable proportion of north temperate forms. But it contains ar-
madillos, cavies, and opossums ; and its birds are all of American
groups, though, owing to the inferior climate and deficiency of
forests, a number of the families of birds peculiar to tropical
America are wanting. Thus there are no manakins, chatterers,
toucans, trogons, or motmots ; but there are abundance of hang-
nests, tyrant-birds, ant-thrushes, tree-creepers, and a fair propor-
tion of humming-birds, tanagers, and parrots. The zoology is
therefore thoroughly Neotropical, although somewhat poor ; and
it has a number of peculiar forms, as the chinchillas, alpacas, etc.,
whioh are not found in the tropical regions except in the high
Andes.
Comparison of Zoological Regions with the Oeographical Di-
visions of the Globe. — Having now completed our survey of the
great zoological regions of the globe, we find that they do not
differ so much from the old geographical divisions as our first
example might have led us to suppose. Europe, Asia, Africa,
Australia, North America, and South America really correspond,
each to a zoological region, but their boundaries require to be
modified more or less considerably ; and if ^te remember this,
62 ISLAND LIFE. [Part L
and keep tlieir extensions or limitations always in our mind, we
may use the terms " South American " or " North American "
as being equivalent to Neotropical and Nearctic, without much
inconvenience ; while " African " and " Australian " equally well
serve to express the zoological types of the Ethiopian and Aus-
tralian regions. Europe and J^sia. require more important mod-
ifications. The European fauna does indeed well represent the
Palflearctic in all its main features ; and if instead of Asia we say
tropical Asia, we have the Oriental region very fairly defined;
so that the relation of the geographical and the zoological pri-
mary divisions of the earth is sufficiently clear. In order to
make these relations visible to the eye and more easily remem-
bered, we will put them in a tabular form :
Herons. Gco^p-aphical Eqoivaleut.
Falffiarctic Ecrope, with north temperate Africa and Asia.
Ethiopian Africa (south of the Sahara), with Madagascar.
Oriental Trofical Asia, to Philippines and Java.
Australian Acstralia, with Pacific islands, Moluccas, etc.
Nearctic North America, to North Mexico.
Neotropical South America, with tropical North America and West Indies.
The following arrangement of the regions will indi(*ate their
geographical position, and to a considerable extent their relation
to each other :
Nearctic Pal-«arctic
I
Oriental
Neo- ETniopiAN
TROPICAL Australian
Chap. IV.] EVOLUTION THE KEY TO DISTRIBUTION. 53
CHAPTER IV.
EVOLUTION THE KEY TO DISTRIBUTION.
Importance of the Doctrine of Evolution. — The Origin of New Species. — Variation
in Animals. — The Amount of Variation in North American Birds. — How New Spe-
cies Arise from a Variable Species. — Definition and Origin of Genera. — Cause of
the Extinction of Species. — The Rise and Decay of Species and Genera. — Discon-
tinuous Specific Areas, why Rare. — ^Discontinuity of the Area o{ Parus palustris,
— Discontinuity of Emberiza schaniclus, — The European and Japanese Jays. —
Supposed Examples of Discontinuity among North American Birds. — Distribution
and Antiquity of Families. — Discontinuity a Proof of Antiquity. — Concluding
Remarks.
In the preceding chapters we have explained the general nat-
ure of the phenomena presented by the distribution of animals,
and have illustrated and defined the new geographical division
of the earth which is found best to agree with them. Before we
go further into the details of our subject, and especially before
we attempt to trace the causes which have brought about the
existing biological relations of the islands of the globe, it is ab-
solutely necessary to have a clear comprehension of the collate-
ral facts and general principles to which we shall most frequent-
ly have occasion to refer. These may be briefly defined as the
powers of dispersal of animals and plants under different condi-
tions— geological and climatal changes — and the origin and de-
velopment of species and groups by natural selection. This last
is of the most fundamental importance, and its bearing on the
dispersal of animals has been much neglected. We therefore
devote the present chapter to its consideration.
As we have already shown in our firet chapter that the distri-
bution of species, of genera, and of families presents almost ex-
actly the same general phenomena in varying degrees of com-
plexity, and that almost all the interesting problems we have to
deal with depend upon the mode of dispereal of one or other of
these ; and as, further, our knowledge of most of these groups,
54
ISLAND LIFE.
[Pa«t I.
in tlio higher auiinals at least, is confined to the Tertiary period
of geology, it is tlierefore uuneceseary for ub to enter into any
questions involving tlio origin of more conapreheiisive groups,
such as classes or orders. This enables ns to avoid most of the
disputed questions as to the development of animals, and to con-
fine ourselves to those general principles regulating the origin
and development of species and genera which were firet laid
down by Mr. Darwin twenty years ago, and have now come to
be adopted by naturalists as established propositions in tlie the-
ory of evolution.
The Oriijin of New Species. — IIow, then, do new species arise,
supposing the world to have been, physically, much as wc now
see it? and what beeomea of them nfler they have arisen? In
the first place, we must remember that new species can only be
formed when and where thcro is room for tJicm. If a continent
is fully stocked with animals, each species being so well adapt-
ed to its mode of life that it can overcome all the dangers to
which it is exposed, and maintain on the average a tolerably
uniform population, then, so long as iio change takes place, no
new species will arise. For every place or station is supposed
to -be filled by creatnres perfectly adapted to all surrounding
conditions, able to defend themselves from all enemies, and to
obtain food notwithstanding the rivalry of many competitors.
But such .1 pei-fect balance of organisms nowhere exists upon
the earth, and probably never has existed. The well-known
fact that some species are very common, while others are very
rare, is an almost certain proof that the one is better adapted to
its position than the other; and this belief is strengthened wlien
we find the individuals of one spocit^ ranging into difforont
climates, subsisting on different food, and competing with differ-
ent seta of animals, while the individuals of another species will
be limited to a small area beyond which they seem unable to ex-
tend. When a change occurs, cither of climate or geography,
some of the small and ill-adapted species will probably diu out
altogether, and thus leave room for others to increase, or for new
forms to occupy their places.
Hut the change will most likely affect even fionrishing species
in different ways, some benelioialiy, others injnrionsly. Or,
Chap. IV.] EVOLUTION THE KEY TO DISTRIBUTION. 55
again, it may affect a great many injuriously, to such an extent
as to require some change in their structure or habits to enable
them to get on as well as before. Now "variation" and the
"struggle for existence" come into play. All the weaker and
less perfectly organized individuals die out, while those which
vary in such a way as to bring them into more harmony with the
new conditions constantly survive. If the change of conditions
has been considerable, then, after a few centuries, or perhaps
even a few generations, one or more new species will bo almost
sure to be formed.
Variaiion in Animals. — To make this more intelligible to
those who have not considered the subject, and to obviate the
difficulty many feel about "favorable variations occurring at the
right time," it will be well to discuss this matter a little more
fully. Few persons consider how largely and universally all
animals are varying. We know, however, that in every genera-
tion, if we would examine all the individuals of any common
species, we should find considerable differences, not only in size
and color, but in the form and proportions of all the parts and
organs of the body. In our domesticated animals we know this
to be the case, and it is by means of the continual selection of
such slight varieties to breed from that all our extremely differ-
ent domestic breeds have been produced. Think of the differ-
ence in every limb, and every bone and muscle, and probably in
every part, internal and external, of the whole body, between a
greyhound and a bull-dog ! Yet if we had the whole series of
ancestors of these two breeds before us, we should probably find
that in no one generation was there a greater difference thau
now occurs in the same breed, or sometimes even the same litter.
It is often thought, however, that wild species do not vary suf-
ficiently to bring about any such change as tliis in the same time ;
and though naturalists are well aware that this is a mistake, it
is only recently that they are able to adduce positive proof of
their opinion.
T/ie Amount of Variaiion in North American Birds, — An
American naturalist, Mr. J. A. Allen, has made elaborate obser-
vations and measurements of the birds of the United States, and
he finds a wonderful and altogether unsuspected amount of va-
56 ISLAND LIFE. [Vart L
riation between individuals of the same species. They differ in
tlie general tint, and in .the markings and distribution of the
colors ; in size and proportions ; in the length of the wings, tail,
bill, and feet; in the length of particular feathers, altering the
shape of the wing or tail ; in the length of the tarsi and of the
separate toes ; and in the length, wudth, thickness, and curvature
of the bill. These variations are very considerable, often reach-
ing to one sixth or one seventh of the average dimensions, and
sometimes more. Thus Turdusfascescens (Wilson's thrush) va-
ried in length of wing from 3.58 to 4.16 inches, and in the tail
from 3.55 to 4 inches; and in twelve specimens, all taken in
the same locality, the wing varied in length from 14.5 to 21 per
cent., and the tail from 14 to 22.5 per cent. In Sialia stalls
(the blue-bird) the middle toe varied from .77 to .91 inch, and
the hind toe from .58 to .72 inch, or more than 21.5 per cent,
on the mean ; while the bill varied from .45 to .56 inch in length,
and from .30 to .38 inch in width, or about 20 per cent, in both
cases. In Dendrcsoa coronata (the yellow-crowned warbler) the
quills vary in proportionate length, so that the first, the second, the
third, or the fourth is sometimes longest ; and a similar variation of
the wing involving a change of proportion between two or more
of the feathers is recorded in eleven species of birds. Color and
marking vary to an equal extent ; the dark streaks on the under-
surface of Melospiza weJodia (the American song-sparrow) be-
ing sometimes reduced to narrow lines, while in other specimens
they are so enlarged as to cover the greater part of the breast
and sides of the body, sometimes uniting on the middle of the
breast into a nearly continuous patch. In one of the small spot-
ted wood-thrushes, Tiirdus ftiscescenSy the colors are sometimes
very pale, and the markings on the breast reduced to indistinct
narrow lines ; while in other specimens the general color is much
darker, and the breast-markings dark, broad, and triangular. All
the variations here mentioned occur between adult males, so that
there is no question of diflferences of age or sex, and the pair last
referred to were taken at the same place and on the same day.'
* These facts are taken from a memoir on **The Mammals and Winter Birds of
Florida/' by J. A. Allen, forming Vol. II., No. 3, of the ** Bulletin of the Museum of
Comparative Zoology at Uarvaixi College,*' Cambridge, Massachusetts.
Chap. IV.] EVOLUTION THE KEY TO DISTRIBUTION. 57
These interesting facts entirely support the belief in the vari-
ability of all animals in all their parts and organs, to an extent
amply suflScient for natural selection to work with. We may,
indeed, admit that these are extreme cases, and that the major-
ity of species do not vary half or a quarter so much as shown in
the examples quoted, and we shall still have ample variation
for all purposes of specific modification. Instead of an extreme
variation in the dimensions and proportions of the various
organs of from 10 to 25 per cent., as is here proved to occm*, we
may assume from 3 to 6 per cent, as generally occurring in the
majority of species ; and if we further remember that the above
excessive variations were found by comparing a number of spec-
imens of each species varying from 50 to 150 only, we may be
sure that the smaller variations we require must occur in con-
siderable numbers among the thousands or millions of individu-
als of which all but the very rare species consist. If, therefore,
we were to divide the population of any species into three groups
of equal extent, with regard to any particular character — as length
of wing or of toes, or thickness or curvature of bill, or strength of
markings — we should have one group in which the mean or av-
erage character prevailed with little variation, one in which the
character was greatly, and one in which it was little, developed.
If we formed our groups, not by equal numbers, but by equal
amount of variation, we should probably find, in accordance with
the law of averages, that the central group, in which the mean
characteristics prevailed, was much more numerous than the ex-
tremes; perhaps twice, or even three times, as great as either of
them, and forming such a series as the following : 10 maximum,
30 mean, 10 minimum development. In ordinary cases we have
no reason to believe that the mean characters or the amount of
variation of a species changes materially from year to year or
from century to century, and we may therefore look upon the
central group as the type of the species which is best adapted to
the conditions in which it has actually to exist. This type will
therefore always form the majority, because the struggle for ex-
istence will lead to the continual suppression of the less perfect-
ly adapted extremes. But sometimes a species has a wide range
into countries which differ in physical conditions, and then it
68
ISLANU LIFE.
[Pabt I.
often happens that one or other of the extremes will predomi-
nate ia a portion of its i-angc. Tliese form loeai varieties ; but
as they occur mixed with tlie other forms, they are not consid-
ered to be distinct species, although they may differ from tlie
other extreme form quite aa mucli as spcuies often do from each
other.
now New Species Arise from a Variable Specie«. — It is now
very easy to understand how, from such a variable species, one
or more new species may arise. Tlie peculiar physical or organ-
ic conditions that render one part of the area better adapted to
an extreme form may become intensified, and the most extreme .
variations tlius having the advantage, they M'ill multiply at the
expense of the rest. If the change of conditions spreads over
the whole area occupied by the species, this one extreme form
will replace tho others; while if the area should be cut in two
by subsidence or elevation, tho conditions of the two parts may
be modified in opposite directions, so aa to be each adapted to
one extreme form; in whicli case the original type will become
extinct, being replaced by two species, each formed by a combi-
nation of certain exti'eme characters which had before existed
in some of its varieties.
The changes of conditions which lead to such selection of va-
rieties ai-e very divcree in nature, and new species may thus be
formed, diverging in many ways from the original stock. The
climate may ehauge from moist to dry, or the reverse, or tho
temperature may increase or diminish for long periods, in cither
case requiring a corresponding change of constitution, of cover-
ing, of vegetable or of insect food, to be met by the selection of
variations of color or of swiftness, of length of bill or of strength
of claws. Again, competitors or enemies may arrive from other
regions, giviug the advantage to snclt varieties as can cliangc
their food, or by swifter flight or greater wariness can escape
their new foes. We may thus easily understand Low a series of
changes may occur at distant intervals, each leading to the se-
lection and preservation of a special set of vtiriations, and thus
what was a single species may become transformed into a group
of allied species differing from each other in u variety of ways,
just as we iind them in nature.
Chap. IV.] EVOLUTION THE KEY TO DISTRIBUTION. 59
Among these species, however, there will be some which will
have become adapted to very local or special conditions, and
will therefore be comparatively few in number and confined to
a limited area ; while others, retaining the more general charac-
ters of the parent form, but with some important change of
stnicture, will be better adapted to succeed in the struggle for
existence with other animals, will spread over a wider area, and
increase so as to become common species. Sometimes these will
acquire such a perfection of organization by successive favorable
modifications that they will be able to spread greatly beyond
the range of the parent form. They then become what are
termed dominant species, maintaining themselves in vigor and
abundance over very wide areas, displacing other species with
which they come into competition, and, under still further
changes of conditions, becoming the parents of a new set of di-
verging species.
Definition and Origin of Ge)iera, — As some of the most im-
portant and interesting phenomena of distribution relate to gen-
era rather than to single species, it will be well here to explain
what is meant by a genus, and how genera are supposed to arise.
A genus is a group of allied species which differs from all
other groups in some well-marked characters, usually of a struct-
ural rather than a superficial nature. Species of one genus usu-
ally differ from each other in size, in color or marking, in the
proportions of the limbs or other organs, and in the form and
size of such superficial appendages as horns, crests, manes, etc. ;
but they generally agree in the form and stnicture of important
organs, as the teeth, the bill, the feet, and the wings. When
two groups of species differ from each other constantly in one
or more of these latter particulars, they are said to belong to dif-
ferent genera. AVe have already seen that species vary in these
more important as well as in the more superficial characters.
If, then, in any part of the area occupied by a species some
change of habits becomes useful to it, all such structural varia-
tions as facilitate the change will be accumulated by natural se-
lection ; and when they have become fixed in the proportions
most beneficial to the animal, we shall have the first species of
a new genus.
ISLAND LIFE.
[Pa-t I.
A creature which has been thus nioJified in importaiit charac-
ters will be a now tyiie, special! j adapted to fill its place in the
economy of nature. It will almost certainly have arisen from
an extensive or dominant group, because only such are sufficient-
ly rich in individuals to afford an ample supply of the necessary
variations, and it will inherit tlio vigor of constitntion and adapt-
ability to a wide nuigo of conditions which gave success to its
ancestors. It will thercfom have every chance in its favor in
the struggle for existence; it may spread widely and displace
many of its nearest allies, and in doing so will itself become
modified superficially and become the parent of a number of
subordinate species. It will now have become a dominant genus,
occupying an entire continent, or perhaps even two or more con-
tinents, spreading in every direction till it comes in contact with
competing forms better adapted to the different environments.
Such a genus may continue to exist during long geological
epochs; but the time will generally come when eitlier physical
changes, or competing forms, or new enemies are too much for
it, and it begins to lose its supremacy. First one, then another,
of its component species will dwindle away and become extinct,
till at last only a few species remain. Sometimes these soon
follow the others, and the whole genus dies out, as thousands of
genera have died out during the long course of the earth's life-
history; but it will also sometimes happen that a few species
will continue to maintain themselves in areas whei-o they are re-
moved from the intlnences that exterminated their fellows.
Cause of the Jirtinction of Sjwcies. — There is good reason to
believe that the most effective agent in the extinction of spcciea
is the preesiue of otlier species, whether as enemies or merely as
eompelitora. If tlierefore any portion of the earth is cut ofE
from the influx of new or more highly organized animals, we
may there expect to find the remains of groups which have else-
where become extinct. In islands which have been long sepa-
rated from their parent continents those conditions are exactly
fulfilled, and it is in such that wc find the most striking examples
of the preservation of fragments of primeval gronpa of animals,
often widely separated from each other, owing to their having
been jirescrved at remote portions of the area of the once wide-
Chap. IV.] EVOLUTION THE KEY TO DISTRIBUTION. 61
spread parental group. There are many other ways in which
portions of dying-out groups jnay be saved. Nocturnal or sub-
terranean modes of life may save a species from enemies or com-
petitors, and many of the ancient types still existing have such
habits. The dense gloom of equatorial forests also affords means
of concealment and protection, and we sometimes find in such
localities a few remnants of low types in the midst of a general
assemblage of higher forms. Some of the most ancient types
now living inhabit caves, like the Proteus ; or bury themselves
in mud, like the Lepidosiren ; or in sand, like the Amphioxus,
the last being the most ancient of all vertebrates; while the
Galeopithecus and Tarsius of the Malay Islands, and the potto
of West Africa, survive amidst the higher mammalia of the Asi-
atic and African continents, owing to their nocturnal habits and
concealment in the densest forests.
The Rise and Decay of Species and Genera, — The preceding
sketch of the mode in which species and genera have arisen,
have come to maturity, and then decay, leads us to some very
important conclusions as to the mode of distribution of animals.
When a species or a genus is increasing and spreading, it neces-
sarily occupies a continuous area which gets larger and larger
till it reaches a maximum ; and we accordingly find that almost
all extensive groups are thus continuous. When decay com-
mences, and the group, ceasing to be in harmony with its envi-
ronment, is encroached upon by other forms, the continuity may
frequently be broken. Sometimes the outlying species may be
the first to become extinct, and the group may simply diminish
in area while keeping a compact central mass ; but more often
the process of extinction will be very irregular, and may even
divide the group into two or more disconnected portions. This
is the more likely to be the case because the most recently
formed species, probably adapted to local conditions, and there-
fore most removed from the general type of the group, will
have the best chance of surviving, and these may exist at sever-
al isolated points of the area once occupied by the whole group.
We may thus understand how the phenomenon of discontinuous
areas has come about, and we may be sure that when allied spe-
cies or varieties of the same species are found widely separated
62 ISLAND LIFE. [Pabt I.
from each other, they wore onec connected by intervening forms
or by each extending till it overlapped the other's area.
Discontinuous iSpccijiv Areas, why Rare. — But although dls-
contitiiions generic ureas, or the separation from each other «f
species whose ancestore must onca h«vc occnpied conterminous
or overlapping areas, are of frequent occurrence, yet undoubted
cases of discontinnous specific areas are very rare, except, as al-
ready stittod, when one portion of a speeies inhabits an island.
A few examples among mammalia Lave been referred to in our
first chapter, but it may be said that these are examples of the
■sary comuion phenomenon of a species being only fonnd in the
station for which its organization adapts it; so that forest or
marsh or mountain animals are of courae only found where there
are forests, marshes, or mountaina. This may be true ; and when
the separate forests or mountains inhabited by ihe same species
arc not far apart, there is little that needs explanation : but in
one of tlie cases referred to there was a gap of a thousand miles
between two of the areas occupied by the species ; and this being
too far for the animal to traverse through an uncongenial terri-
tory, we are forced to the conclnsiou that it must at some former
period, and under different conditions, have occupied a consider-
able portion of the intervening area.
Among birds such cases of specific discontinuity are very rare,
and hardly ever qnite satisfactory. This may be owing to birds
being more rapidly infiiienccd by changed conditions, so that
when a species is divided tho two portions almost always be-
come modified into varieties or distinct species; while auotlicr
reason may be that their powers of flight cause them to occupy,
on tho average, wider and less precisely defined areas than do
the speeios of mammalia. It will be interesting, therefore, to
examine the few cases on record, as we shall thereby obtain ad-
ditional knowledge of tho steps and processes by which tho dis-
tribution of varieties and species has been brought about.
Disconfinuitij of the Area of Paruspalustris. — Mr. Seebohm,
who has travelled and collected in Europe, Siberia, and India,
and possesses extensive and accurate knowledge of Paleearctic
birds, has recently called attention to tho varieties and suh-spc-
cies of tho marsh tit [Parus palustns)y of which he has exam-
Chap. IV.] EVOLUTION THE KEY TO DISTRIBUTION. 63
ined numerous specimens ranging from England to Japan.* The
curious point is that those of Southern Europe and of China are
exactly alike, while all over Siberia a very distinct form occurs,
the sub-species P. horealu. In Japan and Kamtschatka other
varieties are found, which have been named respectively -P. Ja-
ponieus and P. CamischcUJcensis. Now it all depends upon these
forms being classed as sub-species or as true species whether this
is or is not a case of discontinuous specific distribution. If Pa-
rus horealin is a distinct species from Partis palustris^ as it is
reckoned in Gray's " Hand List of Birds," and also in Sharpe and
Dresser's "Birds of Europe," then Panes palustris has a most re-
markable discontinuous distribution as shown in the accompany-
ing map, one portion of its area comprising Central and South
Europe and Asia Minor, the other an undefined tract in Northern
China, the two portions being thus situated in about the same
latitude and having a very similar climate, but with a distance
of about four thousand miles between them. If, however, these
two forms are reckoned as sub-species only, then the area of the
species becomes continuous, while only one of its varieties or
sub-species has a discontinuous area. It is a curious fact that P,
palustris and P. horealis are found together in Southern Scan-
dinavia and in some parts of Central Europe, and are said to differ
somewhat in their note and their habits, as well as in coloration.
Discontinuity of Emheriza schosntches. — The other case is that
of our reed-bunting {Emheriza schoeniclus)^ which ranges over
almost all Europe and AVestern Asia as far as the Yenisei val-
ley and Northwest India. It is then replaced by another smaller
species, E.passerina^ which ranges eastward to the Lena River,
and in winter as far south as Amoy in China; but in Japan the
original species appears again, receiving a new name {E.pyrrhu-
lina)y but Mr. Seebohm assures us that it is quite indistinguish-
able from the European bird.' Although the distance between
these two portions of the species is not so great as in the last ex-
ample, being about two thousand miles, in other respects the
case is a most satisfactory one, because the forms which occupy
the intervening space are recognized by Mr. Seebohm himself
as undoubted species.
* Ibis, 1879, p. 82. « litis, 1870, p. 40.
ISLAND LlPt:.
[pAar I.
The JCuropean and Jajtanesf Jayg. — Anotlicr ease somewhat
reaciubling tlint of tlio inareli tit is afforded by the European
and Japanese jays (6^</rrn^««y/(i«(/«'-*K« and O.Jajionicus). Our
common jay inhabits the whole of Europe except the extreme
north, but is not known to extend anywhei-e into Asia, where it
16 represented by several quite distinct species. (See Map, fron-
tispiece.) Gut the great central island of Japan is inhabited by
a jay {G. Japonicm) which is very like ours, and was formerly
classed as a Biibspeeics only, in which case onr jay would be con-
sidered to have a discontinuous distribution. But the specific
distinctness of the Japanese bird is now universally admitted,
and it is certainly a very remarkable fact that among the twelve
epecics of jays which togetlier range over all temperate Europe
and Asia, one which is bo closely allied to onr English bii'd should
be found at the remotest possible point from it. Looking at tlio
map exhibiting the dislribntion of the several species, we eau
hardly avoid the conclusion that a bird very like our jay once
occupied the whole area of tlie genus, that in various parts of
Asia it became gi-adually iiioditied into a variety of distinct spe-
cies in the maimer already explained, a remnant of the original
type being preserved almost unchanged in Japan, owing prob-
ably to favorable conditions of climate and protection from com-
peting forms.
SuppcMtnl Ei^amph'8 of Di«coniintiili/ among XoHh American
liirdn. — In North America the eastern and M^eatern provinces
are so difEcrcnt in climate and vegetation, and are besides sep-
arated by such remarkable physical barriers — the arid central
plains and the vast ranges of the Rocky Mountains and Sierra
Nevada — that we can hardly ex[)ect to Hnd species whose areas
may bo divided maintaining their identity, ToM-ards the north,
however, the above-named barrio's disappear, the forests being
almost continuuns from east to west, while the mountain-range
is broken up by passes and valleys. It tlius happens that must
species of birds which inhabit both the eastern and western
coasts of the North American continent have maintained their
continuity towards tho north, while even when difforentiutcd into
two or more allied species their areas are often conterminous or
overlapping.
CfiAP.IV.] EVOLUTION THE KEY TO DISTHIBUTION. 65
Almost the only bird that seems to have a really discontinu-
ous range is the species of wren Thryothoru^ Bewickii, of which
the type-form ranges from the east coast to Kansas and Minne-
sota, while a longer-billed variety is found in the wooded parts
of California and as far north as Puget Sound. If this really
represents the range of the species, there remains a gap of about
one thousand miles between its two disconnected areas. Other
cases are those of the greenlet, Vireo8ylvia gilvus^ of the Eastern
States, and its variety V. Swahisonii^ of the Western ; and of the
purple rediBnch, Carpodaous purpureuSy with its variety C. Cali-
f amicus. But, unfortunately, the exact limits of these varieties
are in neither case known ; and though each one is characteristic
of its own province, it is possible they may somewhere become
conterminous, though in the case of the redfinches this does not
seem likely to be the fact.
In a later chapter we shall have to point out some remarkable
cases of this kind where one portion of the species inhabits an
island ; but the facts now given are sufficient to prove that the
discontinuity of the area occupied by a single homogeneous spe-
cies, by two varieties of a species, by two well-marked sub-spe-
cies, and by two closely allied but distinct species, are all differ-
ent phases of one phenomenon — the decay of ill-adapted and
their replacement by better-adapted forms, under the pressure
of a change of conditions either physical or organic. AVo may
now proceed with our sketch of tlie mode of distribution of
higher groups.
Distribution aiid Antiquity of Families, — Just as genera are
groups of allied species distinguished from all other groups by
some well-marked structural characters, s>o families are groups
of allied genera distinguished by more marked and more impor-
tant characters, which are generally accompanied by a peculiar
outward form and style of coloration, and by distinctive habits
and mode of life. As a genus is usually more ancient than any
of the species of which it is composed, because during its growth
and development the original rudimentary species becomes sup-
planted by more and more perfectly adapted forms, so a family
is usually older than its component genera, and during the long
period of its life-history may have survived many and great ter-
5
ISLAND LIFE.
[I'AI
:I-
restrial and organic clianges. Many families of llie liigber ani-
nials liaVQ now ati almost world-wide extension, or at least range
over several continents; and it seems probable tbat nil families
wliieli liavG eiirvived long enougli to develop a considerable va-
riety of generic and epeeilie forms bave also at one time or other
occupied an extensive area.
Viseoniinuiti/ a Proof of AntiquUy. — Discontinuity will
llierefore be an indication of antiquity; and tlie more widely
the fragments are scattered, the more ancient we may usnally
presnme tbe parent gronp to lie. A striking example is fur-
nished by tbe strange reptilian fisbes forming the order or enb-
order Dipnoi, which includes tbe Lepidosiren and its allies.
Only three or four living species are known, and these inhabit
tropical rivers gitnated in the remotest continents. The Ja-jjIiIo-
siren- paradoxa is only known from the Amazon and some oth-
er South American rivers. An allied species, I^j/idoairen an-
ned^ts, eometimea placed in a distinct genus, inhabits tbe Oam-
bia in West Africa; while the recent discovery in Eastern Ans-
tralia of tbe Ceratodue, or mud-fisb, of Queensland adds another
form to the same isolated group. Numerous fossil teeth long
known from thcTriassic. beds of this country, and also found in
Germany and India in beds of tbe same age, agree so closely
with those of tbe living Ceratodus that both are referred to tbe
same gends. No more recent traces of any such animal bave
been discovered, bnt the Carboniferous Ctenodna and tbe De-
vonian Diptepiis evidently belong to the same gronp, while in
North America the Devonian rocks have yielded a gigantic al-
lied form which has been named Hcliodns by Professor New-
berry. Tlins an enurmons range in time is accompanied by a
very wide and scattered distribution of the existing species.
Whenever, tlicrefore, we find two or more living genera he-
longing to the same family or order, lint not very closely allied
to each other, we may bo sure tbat they arc the remnants of
ft once extensive group uf genera; and if we tind tliem now
isolated in remote parts of the globe, the natural inference is
that the family of which they are frngnients once had an area,
embracing the countries in which they are found. Yet this
Biniple and very obvious explanation has rarely been adopted
Chap. IV.] EVOLUTION THE KEY TO DISTRIBUTION. 67
by naturalists, who Lave instead imagined clianges of land and
sea to aflford a direct passage from the one fragment to the
other. If there were no cosmopolitan or very wide-spread fam-
ilies still existing, or even if such cases were rare, there would
be some justiiBcation for such a proceeding ; but as about one
fourth of the existing families of land mammalia have a range
extending to at least three or four continents, while many which
are now represented by disconnected genera are known to have
occupied intervening lands or to have had an almost continuous
distribution in Tertiary times, all the presumptions are in favor
of the former continuity of the group. We have also in many
cases direct evidence that this former continuity was eflfected
by means of existing continents, while in no single case has it
been shown that such a continuity was impossible, and that it
either was or must have been eflfected by means of continents
now sunk beneath the ocean.
C<yncludi7i/f Remarks, — ^When writing on the subject of dis-
tribution, it usually seems to have been forgotten that the theory
of evolution absolutely necessitates the former existence of a
whole series of extinct genera filling up tlie gap between the
isolated genera which in many cases now alone exist ; while it
is almost an axiom of "natural selection" that such numerous
forms of one type could only have been developed in a wide
area and under varied conditions, implying a great lapse of
time. In our succeeding chapters we shall show that the known
and probable changes of sea and land, the known changes of
climate, and the actual powers of dispersal of the diflferent groups
of animals were such as would have enabled all the now discon-
nected groups to have once formed parts of a continuous series.
Proofs of such former continuity are continually being obtained
by the discovery of allied extinct forms in intervening lands;
but the extreme imperfection of the geological record as re-
gards land animals renders it unlikely that this proof will bo
forthcoming in the majority of cases. The notion that if such
animals ever existed their remaius would certainly be found is
a snpei'stition which, notwithstanding the eflforts of Lyell and
Darwin, still largely prevails among naturalists; but until it is
got rid of, no true notions of the former distribution of life
upon the earth can be attained.
68 ISLAND LIFE. [Pabt L
CHAPTER V.
THE POWERS OF DISPERSAL OF ANIMALS AND PLANTS.
Statement of the General Question of Dispei'snl. — The Ocean as a Barrier to the
Dispersal of Mammals. — The Dispersal of Birds. — ^IMie Dispersal of Reptiles. —
The Dispersal of Insects. — The Dispersal of Land Mollusca. — Great Antiquity of
Land Shells. — Causes Favoring the Abundance of Land Shells. — The Dispersal
of Plants. — Special Adaptability of Seeds for Dispersal. — Birds as Agents in the
Dispersal of Seeds. — Ocean Currents as Agents in Plant-dispersal. — Dispersal
along Mountain-chains. — Antiquity of Plants as Affecting their Distribution.
In order to nnderstaud tlie many curious anomalies we meet
with in studying the distribution of animals and plants, and to
be able to explain how it is that some species and genera have
been able to spread widely over the globe, while others are con-
fined to one hemisphere, to one continent, or even to a single
mountain or a single island, we must make some inquiry into
the different powers of dispersal of animals and plants, into the
nature of the barriers that limit their migrations, and into the
character •of the geological or climatal changes which have fa-
vored or checked such migrations.
The first portion of the subject — that which relates to the
various modes by which organisms can pass over wide areas of
sea and land — has been fully treated by Sir Charles Lyell, by
Mr. Darwin, and many other writers, and it will be only neces-
sary here to give a very brief notice of the best-known facts on
the subject, which will be further referred to when we come to
discuss the particular cases that arise in regard to the faunas
and floras of remote islands. But the other side of the question
of dispersal — that which depends on geological and climatal
changes — is in a far less satisfactory condition; for, though
much has been written upon it, the most contradictory opinions
still prevail, and at almost every step we find ourselves on the
battle-field of opposing schools in geological or physical science.
Chap. v.] DISPERSAL OF ANIMALS AND PLANTS. 69
As, however, these questions lie at the very root of any general
solution of the problems of distribution, I have given much
time to a careful examination of the various theories that have
been advanced, and the discussions to which they have given
rise ; and have arrived at some definite conclusions which I vent-
ure to hope may serve as the foundation for a better comprehen-
sion of these intricate problems. The four chapters which follow
this are devoted to a full examination of these profoundly interest-
ing and important questions, after which we shall enter upon our
special inquiry — ^the nature and origin of insular faunas and floras.
The Ocean as a BarAer to the Dispersal of Mammals. — A
wide extent of ocean forms an almost absolute barrier to the dis-
persal of all land animals, and of most of those which are aerial,
since even birds cannot fly for thousands of miles without rest
and without food, unless they are aquatic birds which can find
both rest and food on the surface of the ocean. We may be
sure, therefore, that without artificial help neither mammalia nor
land birds can pass over very wide oceans. The exact width
they can pass over is not determined, but we have a few facts to
guide us. Contrary to the common notion, pigs can swim very
well, and have been known to swim over five or six miles of sea,
and the wide distribution of pigs in the islands of the Eastern
Hemisphere may be due to this power. It is almost certain, how-
ever, that they would never voluntarily swim away from their
native land, and if carried out to sea by a flood they would cer-
tainly endeavor to return to the shore. We cannot, therefore,
believe that they would ever swim over fifty or a hundred miles
of sea, and the same may be said of all the larger mammalia.
Deer also swim well, but there is no reason to believe that they
would venture out of sight of land. With the smaller, and es-
pecially with the arboreal, mammalia there is a much more ef-
fectual way of passing over the sea, by means of floating trees,
or those floating islands which are often formed at the mouths
of great rivers. Sir Charles Lyell describes such floating islands
which were encountered among the Moluccas, on which trees
and shrubs were growing on a stratum of soil, which even formed
a white beach round the margin of each raft. Among the Phil-
ippine Islands similar rafts with trees growing on them have
ISLAND LIFE.
[Pa«t 1.
been setu after hurricanes; and it is easy tu uudcrstaiid liow, if
the sea were tolerably calm, euch a mft might be carried along
by a current, aided by the wind acting on the trees, till, after a
paseage of several weeks, it miglit arrive safely on the shores of
some land hundreds of miles awny from its starting-point. Such
small animals as squirrels and mice might have been carried
away on the trees which formed part of such a raft, and might
thus colonize a new island; though, as it would require a pair
of the same species to bo carried away together, sncli accidents
would no doubt bo rare. Insects, Iiowever, and land shells would
almost certainly he abundant on such a raft or island, and in this
way we may account for the wide dispersal of many species of
both these groups.
Notwithstanding the occasional action of such causes, wc can-
not suppose that they have been etfectivc in the dispersal of
nianiiualia as a whole ; and whenever we find that a considerable
number of the mammals of two countries e.\hibit distinct niarks
of relationship, we may be sure that an actual land connection,
or, at all events, an approach to within a very few miles of each
other, has at one time existed. IJut a considerable number of
identical mammalian families, and even genei-a, are actually
found in all the great continents, and the present distribution
of land upon tlie globe renders it easy to see how they have
been able to disperse themselves so widely. All the great land
masses I'adiate from the arctic regions as a eoiumon centre, the
only break being at Behring Strait, whicli is so shallow that a
rise of less than a tliousand feet would form a broad isthmus
connecting Asia and America as far south as the parallel of 00°
N. Continnity of land, therefore, may be said to exist already
for all parts of the world (except Australia and a number of
large islands, which will he considered separately), and we liavo
thus no difficulty in the way of that former wide diffusion of
many groups which we maintain to be the only explanation of
most anomalies of distribution otlier than such as may be con-
nected with nnsuitability of climate.
Tho DUpersal of Birds. — WJicrever mammals can migrate,
other vertebrates can generally follow with even greater facility.
Birds, liaving the power of flight, can pass over wide arms of
Chap, v.] DISPERSAL OF ANIMALS AND PLANTC. 71
the sea, or even over extensive oceans, when these are, as in the
Pacific, studded with islands to serve as resting-places. Even
the smaller land birds are often carried by violent gales of wind
from Europe to the Azores, a distance of nearly a thousand
miles, so that it becomes comparatively easy to explain the ex-
ceptional distribution of certain species of birds. Yet on the
whole it is remarkable how closely the majority of birds follow
the same laws of distribution as mammals, showing that they
generally require either continuous land or an island-strewn sea
as a means of dispersal to new homes.
The Dispersal of lieptiles. — Reptiles appear at first sight to
bo as much dependent on land for their dispersal as mammalia ;
but they possess two peculiarities which favor their occasional
transmission across the sea — the one being their greater tenacity
of life, the other their oviparous mode of reproduction. A large
boa-constrictor was once floated to the island of. St. Vincent
twisted round the trunk of a cedar-tree, and was so little injured
by its voyage that it captured some sheep before it was killed.
The island is nearly two hundred miles from Trinidad and the
coast of South America, whence it almost certainly came.*
Snakes are, however, comparatively scarce on islands far from
continents, but lizards are often abundant; and though these
might also travel on floating trees, it seems more probable that
there is some as yet unknown mode by which their eggs are
safely, though perhaps very rarely, conveyed from island to isl-
and. Examples of their peculiar distribution will be given when
we treat of the fauna of some islands in which they abound.
The Dispersal of Amphibia and Fresh - water Fishes, — The
two lower groups of vertebrates, amphibia and fresh-water fishes,
possess special facilities for dispersal, in the fact of their eggs
being deposited in water, and in their aquatic or semi-aquatic
habits. They have another advantage over reptiles in being ca-
pable of flourishing in arctic regions, and in the power possessed
by their eggs of being frozen without injury. They have thus,
no doubt, been assisted in their dispersal by floating ice, and by
that approximation of all the continents in high northern lati-
> Lyeirs "Principles of Geology," II., p. 309.
72 ISLAND LIFE.
tudes Tvliicli lias been tlio chief agent in producing tlio gencrHi
uniformity in the animal prodiictione of the globe. Some genera
of Jlatruchia have almost a world-wide distribtition ; wlule the
Tailed Batrachia, such as the newts and salamanders, are almost
entirely confined to the Northern Hemisphere, some of the gen-
era spreading over the whole of the north temperate zone. Fresh-
water fishes have often a very wide range, the same species being
Bometinies found in all the rivers of a continent. This is no
doubt chiefly dno to the ivant of permanence in river basins, es-
pecially in their lower portions, where streams belonging to dis-
tinct systems often approach each other and may bo made to
change their course from one to the other basin by very elight
elevations or depressions of the land. Hurricanes and water-
spouts also often carry considerable quantities of water fi'om
ponds and rivers, and thus disperse eggs and even small fishes.
As a rule, however, the same species are not often found in
countries separated by a considerable extent of sea, and in the
tropics rarely the earae genera. The exceptions are in the colder
regions of the earth, where the transporting power of ico may
have come into play. High ranges of monnlains, if continuous
for long distances, rarely have the same species of fish in the
rivers on their two sides. Where exceptions occur, it is often
due to the great antiquity of the group, which has survived so
many changes in physical geography that it has been able, step
by step, to reach countries which are separated by barriers im-
passable to more recent types. Yet another and more eflicient
explanation of the distribution of this group of animals is the
fact that many families and genera inhabit both fi-esh and salt
water; and there Is reason to believe that many of the fishes
now inhabiting the tropical rivers of both liemisphcres have
arisen from allied marine fonus becoming gradually modified
for a life in fresh water. By some of these various causes, or a
combination of them, most of the facts in the distribution of
fishes can be explained without nincli difficulty.
The Dhpersal of Insects. — In the enormous group of insects
the means of dispei'eal among land animals reach their maxi-
mum. Many of them Lave great powers of tliglit, and from
their extreme lightness they can be carried immense distances
Chap, v.] DISPERSAL OF ANIMALS AND PLANTS. 73
by gales of wind. Others can survive exposure to salt water
for many days, and may thus be floated long distances by ma-
rine currents. The eggs and larvae often inhabit solid timber,
or lurk under bark or in crevices of logs, and may thus reach
any countries to which such logs arc floated. Another impor-
tant factor in the problem is the immense antiquity of insects,
and the long persistence of many of the best-marked types.
The rich insect fauna of the Miocene period in Switzerland con-
sisted largely of genera still inhabiting Europe, and even of a
considerable number identical, or almost so, with living species.
Out of 156 genera of Swiss fossil beetles, no less than 114 are
still living; and the general character of the species is exactly
like that of the existing fauna of the Northern Ileniisphere in a
somewhat more southern latitude. There is, therefore, evidently
no difficulty in accounting for any amount of dispersal among
insects ; and it is all the more surprising that with such powers
of migration they should yet be often as restricted in their range
as the reptiles or even the mammalia. The cause of this won-
derful restriction to limited areas is undoubtedly the extreme
specialization of most insects. They have become so exactly
adapted to one set of conditions that when carried into a new
country they cannot live. Many can only feed in the larva state
on one species of plant ; others are bound up with certain groups
of animals on which they are more or less parasitic. Climatal
influences have a great effect on their delicate bodies; while,
however well a species may be adapted to cope with its enemies
in one locality, it may be quite unable to guard itself against
those which elsewhere attack it. From this peculiar combina-
tion of characters it happens that among insects are to be found
examples of the widest and most erratic dispersal and also of the
extremest restriction to limited areas ; and it is only by bearing
these considerations in mind that we can find a satisfactory ex-
planation of the many anomalies we meet with in studying their
distribution.
The Dispersal of Land MoUusca. — The only other group of
animals we need now refer to is that of the air-breathing mol-
lusca, commonly called land shells. These are almost as ubiqui-
tous as insects, though far less numerous ; and their wide distri-
ISLAND LlfE.
[Pakt I.
bution ia by no moans so easy to expluiit. TIig genera bnve
usuiilly a very ^-ide, fliid often a cosmopolitan, range, while the
species are rather restricted, and Eometimes wonderfnlly bo.
Kot only do single islands, however smnll, often possess peculiar
species of Iniid sliells, but sometimes single monntains or valleys,
or even a patticiilar mountain-side, possess species or varieties
found nowhere else upon the globe. It is pretty certain that
tbey have no means of passing over the sea but such as ai-e very
rare and exceptional. Some which possess an operculum, or
which close the mouth of the shcl! with a diaphragm of secroted
mucus, may float across narrow anus of the sea. especially when
protected in the crevices of logs of timber ; while in the young
state when attached to leaves or twigs they may be carried long
distances by hurricanes.' Owing to their exceedingly slow mo-
tion, their powers of voluntary dispersal, even on land, iii"e very
limited, and this will explain the extreme restriction of their
range in many cases.
Great Antiquity of Laiul S/ielfs. — The clew to the almost uni-
versal distribution of the several families and of many genera
is to be found, however, in their immense antiquity. In the
PlioceuQ and Miocene formations most of the land shells arc
either identicitl with living species or closely allied to them;
while even in the Eocene almost all are of living genera, and
ono Britisli Kocene fossil still lives in Te.\as. Strange to say,
no true land shells havo been discovered in the Secondary for-
mations ; but they must certainly have abounded, for in the far
more ancient Paltpozoic coal measures of Nova Scotia two spe-
cies belonging to the living genera I'upa and Zonites have been
found in corisiderable abundance.
Lund shells havo therefore survived all the revolutions the
earth has undergone since Palaeozoic times. They have been
' Mr. Dnrwin fuund ihnt Ihe Inrgo Helix pomaiia lived ofier immersion in Bcn-
wiuor fur iweoiy dnyt, It ia hnnlly likely ihat lliis i* ilie exirema limit of llidr
powers of oiidurnllci;, but «ren tliii would nitow of tlicir being flonled many linndred
mllM nt u ■ti'clcli ; and if wc lugijiuse the Bliell to ba pnrtiatly |imiecled in iJie creviee
nf fl log of wood, nnd to be lliua ont of wntw in cnitn wenllier, tlis distance might
exieml to it tbousnnd miles or more. The oggi of frwh-waler mollniea nre known
lo ntinrli ilicmsi-lvM to tlia foet of oquntlc liirda, and ihi« is mpposod to neconnt for
llieir very wiile ditTuiiun.
Chap, v.] DISPERSAL OF ANIMALS AND PLANTS. 73
able to spread slowly but surely into every land that has ever
been connected with a continent, while the rare chances of trans-
fer across the ocean, to which we have referred as possible, have
again and again occurred during the almost unimaginable ages
of their existence. The remotest and most solitary of the isl-
ands of the mid-ocean have thus become stocked with them,
though the variety of species and genera bears a direct relation
to the facilities of transfer, and the shell fauna is never very
rich and varied, except in countries which have at one time or
other been united to some continental land.
Causes FavorirKj the Ahxuidan^e of Land Shells. — The abun-
dance and variety of land shells arc also, more than those of any
other class of animals, dependent on the nature of the surface
and the absence of enemies; and where these conditions are
favorable, their forms are wonderfully luxuriant. The first con-
dition is the presence of lime in the soil, and a broken surface
of country with much rngged rock offering crevices for conceal-
ment and hybernation. The second is a limited bird and mam-
malian fauna, in which such species as are especially shell-eaters
shall be rare or absent. Both these conditions are found in cer-
tain largo islands, and pre-eminently in the Antilles, w^hich pos-
sess more species of land shells than any single continent. If we
take the whole globe, more species of land shells are found on
the islands than on the continents — a state of things to which no
approach is made in any other group of animals whatever, but
which is perhaps explained by the considerations now suggested.
The Dispersal of Plants, — The ways in which plants are dis-
persed over the earth, and the special facilities they often pos-
sess for migration, have been pointed out by eminent botanists,
and a considerable space might bo occupied in giving a sum-
mary of w^hat has been written on the subject. In the present
work, however, it is only in two or three chapters that I discuss
the origin of insular floras in any detail ; and it will therefore
l)e advisable to adduce any special facts when they are required
to support the argument in particular cases. A few general re-
marks only will tlierefore be made here.
Special AdaptabUity of Seeds for Dispersal. — Plants possess
many great advantages over animals as regards the power of
70 ISLAND LIFE. [I'*iir !.
dispersal, since they are all propagated by seeds or spores, wLicli
are hardier than the eggs of even insects, and retain their vital-
ity for a much longer time. Seeds may lie dormant for many
years and then vegetate, while they endure extremes of lieat, of
cold, of drought, or of moisture which would almost always be
fatal to animal germs. Among the causes of tlie dispersal of
seeds J)e Candollo enumerates the wind, rivers, ocean currents,
icebergs, birds and other animals, and liiiman agency. Great
MUinbers of seeds are specially adapted for transport by one or
other of these agencies. Many are very light and have winged
appendages, pappus, or down, which enables theni to be carried
enormous distitiiccs. It is true, as De Candolle remarks, that
we have no actual proofs of their being so carried; but this
is not surprising when we consider how small and inconspic-
uous most seeds are. Supposing every year a million seeds
were brought by the wind to the British Isles from the Con-
tinent, this would be only ten to a square mile, and the ob-
servation of a lifetime might never detect one ; yet a hun-
dredth part of this number would serve in a few centuries to
stock an island like Britain with a gi-eat variety of Continental
plants.
When, however, we consider the enormous quantity of seeds
produced by plants; that great nnmbers of these are more or
less adapted to be carried by the wind ; and that winds of great
violence and long duration occur in most parts of the world, we
are as sure that seeds must be carried to great distances as if
we had seen them so carried. Sucli storms carry leaves, hay,
dust, and many small objects to a great height in the air, while
many insects have been conveyed by them for hundreds of
miles out to sea and far beyond what their unaided powcra of
flight could have effected.
Jlirili as Affmts in tfie Dispersal of Plants. — Birds are un-
doubtedly important agents in the dispersal of plants over wide
spaces of ocean, cither by swallowing fruits and rejecting the
seeds in a state tit for gcrintnntion, or by the seeds becoming at-
tached lo the plumage of ground-nesting birds, or to the feet of
aquatic birds embedded in small quantities of mud or eartli.
lllustriitions of these variona modes of transport will be found
CUAP. v.] DISPERSAL OF ANIMALS AND PLANTS. 77
in Chapter XII. when discussing the origin of tlie flora of the
Azores and Bermuda.
Ocean Currents as Agents in Pluntrdispersal. — Ocean currents
are undoubtedly more important agents in conveying seeds of
plants than they are in the case of any other organisms, and a
considerable body of facts and experiments liave been collected
proving that seeds may sometimes be carried in this way many
thousand miles and afterwards germinate. Mr. Darwin made a
series of interesting experiments on this subject, some of which
will be given in the chapter above referred to.
Dispersal along Moxmtain-chains. — These various modes of
transport are, as will be shown when discussing special cases,
amply sufficient to account for the vegetation found on oceanic
islands, which almost always bears a close relation to that of the
nearest continent; but there are other phenomena presented by
the dispersal of species and genera of plants over very wide
areas, especially when they occur in widely separated portions of
the Northern and Southern hemispheres, that are not easily ex-
plained by such causes alone. It is here that transmission along
mountain -chains has probably been eflfective; and the exact
mode in which this has occurred is discussed in Chapter XXIII.,
where a considerable body of facts is given showing that exten-
sive migrations may be effected by a succession of moderate
steps, owing to the frequent exposure of fresh surfaces of soil
or debris on mountain sides and summits, offering stations on
which foreign plants can temporarily establish themselves.
Antiquity of Plants as Affecting their Distribution. — ^We have
already referred to the importance of great antiquity in ena-
bling us to account for the wide dispersal of some genera and
species of insects and land shells, and recent discoveries in fossil
botany show that this cause has also had great influence in the
case of plants. Eich floras have been discovered in the Miocene,
the Eocene, and the Upper Cretaceous formation, and these con-
sist almost wholly of living genera, and many of them of species
very closely allied to existing forms. We have therefore every
reason to believe that a large number of our plant species have
surnved great geological, geographical, and climatal changes ;
and this fact, combined with the varied and wonderful powers
78 ISLAND LIFE. [Part L
of dispersal many of tliem possess, render it far less diflScult to
underetand the examples of wide distribution of the genera and
species of plants than in the case of similar instances among an-
imals. This subject will be further alluded to when discussing
the origin of the New Zealand flora in Chapter XXII.
Chap. VI.] GEOGRAPHICAL AND GEOLOGICAL CHANGES. 79
CHAPTER VI.
GEOGRAPHICAL AND GEOLOGICAL CHANGES: THE PERMANENCE
OF CONTINENTS.
Changes of Land and Sea, their Nature and Extent. — Shore-deposits and Stratified
Rocks. — The Movements of Continents. — Supposed Oceanic Formations ; the
Origin of Chalk. — Fresh-water and Shore Deposits as Proving the Permanence of
Continents. — Oceanic Islands as Indications of the Permanence of Continents and
Oceans. — General Stability of Continents with Constant Change of Form. — Effect
of Continental Changes on the Distribution of Animals. — Changed Distribution
Proved by the Extinct Animals of Different Epochs. — Summary of Evidence for
the General Permanence of Continents and Oceans.
The clhinges of land and sea wliicli have occurred in particu-
lar cases will be described when we discuss the ori<ijin and rela-
tions of the faunas of the different classes of islands. "We have
here only to consider the general character and extent of such
changes, and to correct some erroneous ideas which are prevalent
on the subject.
Changes of Land and Sea^ their Nature and Extent. — It is a
very common belief that geological evidence proves a complete
change of land and sea to have taken place over and over again.
Every foot of dry land has undoubtedly, at one time or other,
formed part of a sea-bottom ; and we can hardly exclude the sur-
faces occupied by volcanic and fresh -water deposits, since in
many cases, if not in all, these rest upon a substratum of marine
formations. At first sight, therefore, it seems a necessary infer-
ence that when the present continents were under water there
must have been other continents situated where we now find
the oceans, from which the sediments came to form the various
deposits we now see. This view was held by so acute and
learned a geologist as Sir Charles Lyell, who says, " Continents,
therefore, although permanent for whole geological epochs, shift
their positions entirely in the course of ages." * Mr. T. Mellard
> "Principles of Geology," 1 lih ed., Vol. I., p. 258.
80
ISI^HD LIf H.
[PA«rI.
Reado, late President of the Geological Society of Livei'iiool, so
recently as 1878, saj-e, " While believing that the ocean depths
are of enormotiB age, it is impossible to resist other evidences
that they have once been land. The very continuity of animal
and vegetable life on the globe points to it. The molluscous
fauna of the eastern coast of North America is very similar to
that of Europe, and this could not liave happened without lit-
toral continuity ; yet there are depths of 1500 fathoms between
these continents.'" It is certainly strange that a geologist
ehould not remember the recent and loug-continucd warm cli-
mates of the arctic regions, and see that a connection of Noi'tli-
ern Europe by Iceland witli Greenland and Ijibrador over a sea
far less than a thousand fathoms deep would furnish the "lit-
toral continuity" required. Again, in the same pamphlet Mr.
Ileade says, " It can be uiathematically demonstrated that the
whole, or nearly the whole, of the sea-bottom has been at one
time or other dry land. If it were not so, and the oscillations
of the level of the land with respect to the sea were con&ned
within limits near the present continents, the results would have
boon a gradual diminution instead of development of the calcare-
ons rocks. To state the case in common language, tlie calcareous
portion of the rocks would have been washed ont during the
inntations, the destruction and re-deposit of the continental
rocks, and eventually deposited in the depths of the immutable
soa far from land. Immense beds of limestone would now exist
ut the bottom of the ocean, while the land would be composed
of sandstones and argillaceous shales. The evidence of chemis-
try tlius confirms the inductions drawn from the distribution of
animal life npon the globe."
So far from this being a " mathematical demonstration," it ap-
pears to me to 1)0 a complete misinterpretation of the facte.
Animals did not create the limo which tliey secrete from the sea-
water, and therefore wo have every reason to believe tiiut the
inorganic sources which originally supplied it still keep np that
supply, though perhaps in diminished quantity. Again, the
great lime-secreters — corals — work in water of moderate deptli
II Inilox of GeoloBicil Time."
Chap. VI.] GEOGRAPHICAL AND GEOLOGICAL CHANGES. 81
(that is, near land), while there is no proof whatever that there is
any considerable accumulation of limestone at the bottom of the
deep ocean. On the contrary, the fact ascertained by the Chal-
lenger^ that beyond a certain depth the " calcareous " ooze ceases,
and is replaced by red and gray clays, although the calcareous
organisms still abound in the surface waters of the ocean, shows
that the lime is dissolved again by the excess of carbonic acid
usually found at great depths, and its accumulation thus pre-
vented. As to the increase of limestones in recent as compared
with older formations, it may be readily explained by two con-
siderations : in the first place, the growth and development of
the land in longer and more complex shore-lines, and the in-
crease of sedimentary over volcanic formations, may have offered
more stations favorable to the growth of coral, while the solubil-
ity of limestone in rain-water renders the destruction of such
rocks more rapid than that of sandstones and shales, and would
thus lead to their comparative abundance in later as compared
with earlier formations.
However weak we may consider the above-quoted arguments
against the permanence of oceans, the fact that these arguments
are so confidently and authoritatively put forward renders it
advisable to show how many and what weighty considerations
can be adduced to justify the opposite belief, which is now rap-
idly gaining ground among students of earth-history.
Shore -deposits and Stratified Hocks. — If we go round the
shores of any of our continents, we shall always find a consid-
erable belt of shallow water, meaning thereby water from a
hundred to a hundred and fifty fathoms deep. The distance
from the coast-line at which such depths are reached is seldom
less than twenty miles, and is very frequently more than a hun-
dred, while in some cases such shallow seas extend several hun-
dred miles from existing continents. The great depth of a
thousand fathoms is often reached at thirty miles from shore,
but more frequently at about sixty or a hundred miles. Bound
the entire African coast, for example, this depth is reached at
distances varying from forty to a hundred and fifty miles (ex-
cept in the Ked Sea and the Strait of Mozambique), the aver-
age being about eighty miles.
G
ISLAHD LITE.
[Paw I.
iS'ow the iinmerous Epeciiiieiis of sea-bottoms colleeted during
the voyage of tliu Vkallenger eliow tliat Inie shoi-e-deposits —
that is, materials deniiJcd from tlie lauil and carried down us
sedimeut by rivors — aro uliaost always confined witliin a dis-
tance of fifty or a hundred miles of the coast, the linest mud
only being sometimes earried a hundred and iifty or, rarely,
two hundred iiiilcs. As the sediment varies in coarseness and
density, it is ovideut that it will sink to the bottom at iincqnal
distances, the hulk of It sinking comparatively near shore, wliile
only the very finest and (ilmost impalpable mud will he carried
out to the farthest limits. lieyond these limits the only depos-
its (with few exceptions) are organic, consisting of the sliells of
minute calcareous or siliceous organisms with some decomposed
pumice and volcanic dust which fiouCs out to mid-ocean. It
follows, tliercforc, that by far the larger part of all etratiticd
deposits, especially those which consist of sand or pebbles or any
visible fragments of rock, must have been formed within fifty
or a hundred miles of then existing continents; or if at a
greatci' distance, in shallow inland seas receiving deposits from
more sides than one, or in certain exceptional areas where deep
ocean currents carry the dohris of land to greater distances,'
If we now examine the stratified rocks found in the very
centre of all our great continents, we find them to consist of
sandstones, limestones, conglomerates, or shales, which must,
aa wc havo seen, have been deposited witliin a comparatively
short distance of a sea-ehoro. Professor Archibald (ieikie says,
" Among the thickest masses of sedimentary rock — those of the
ancient i'alasozoift systems — no features recur more continnally
than the alternations of dltferent sediments, and the recurrence
of BUpfacea covered with well-preserved ripplc-marks, trails and
' In li>> "Preliminnry Report on Oceanic Deposit," Mr. Murrnvinyt, "Ichnibccn
ronnd Ihiit llio deposits taking place nenr continent* nnd inlands have racaivcd Iheir
chief charncteriKtio rrom the preaence of tlie debris of adjacent laiida. In aonie
cnies these deposits eitlend to n dieliince of over a hundred and Rfry miles ttara
ihB const."— /Vx-wrfisw <•/ lilt liosal &ei«/y. Vol, XXIV.. |J. CIO.
"The maturiiili i>i suspension appear tu lie almttat entirely Jepoiilod wiihln tuo
Uanind miles of the \im<l."—Proc€fdmg$ of lit HoyolSoculga/EiiMmryli, 1870-77,
p. 2.i3.
Chap. VI.] GEOGRAPHICAL AND GEOLOGICAL CHANGES. 83
burrows of annelides, polygonal and irregular desiccation-marks,
like the cracks at the bottom of a sun-dried muddy pool. These
phenomena unequivocally point to shallow and even littoral
waters. They occur from bottom to top of formations which
reach a thickness of several thousand feet. They can be inter-
preted only in one way — viz., that the formations in question be-
gan to be laid down in shallow water; that during their forma-
tion the area of deposit gradually subsided for thousands of
feet ; yet that the rate of accumulation of sediment kept pace,
on the whole, with this depression ; and hence that the original
shallow-water character of the deposits remained, even after the
original sea-bottom had been buried under a vast mass of sedi-
mentary matter." He goes on to say that this general state-
ment applies to the more recent as well as to the more ancient
formations, and concludes, " In short, the more attentively the
stratiKed rocks of the earth are studied, the more striking be-
comes the absence of any formations among tliem which can
legitimately be considered those of a deep sea. Tliey have all
been deposited in comparatively shallow water." *
The arrangement and succession of the stratified rocks also
indicate the mode and place of their formation. We find them
stretching across the country in one general direction, in belts
of no great width, though often of immense length, just as we
should expect in shore-deposits; and they often thin out and
change from coarse to fine in a definite manner, indicating the
position of the adjacent land from the debris of which they
were originally formed. Again quoting Professor Geikie, "The
materials carried down to the sea would arrange tliemselves
then as they do still, the coarser portions nearest the shore, the
finer silt and mud farthest from it. From the earliest geolog-
ical times the great area of deposit has been, as it still is, the
marginal belt of sea-floor skirting the land. It is there that nat-
ure has always strewn the dust of continents to be."
The Movements of Continents. — As we find these stratified
rocks of different periods spread over almost the whole surface
of existing continents where not occupied by igneous or meta-
* ** Geogrnphicnl Evolution," Proceedings of the Royal (Jeographical Society ^ 1871),
p. 426.
84
ISLAND LIFE.
[Pak* I.
morpliic rneks, it follows tliat nt one period or another each
part of tho continent )ms been under tlic eeii, but nt the same
time not far from the shore. Oeologista now recognize two
kinds of movements by which the deposits bo formed have been
elevated into dry land — in the one case the strata remain almost
]evel and undisturbed, in the other they are contorted and crum-
pled, often to an enormous extent. The former often prevails
in plains and plateaus, while the latter ia almost always found
in the great mountain-ranges. We are thus led to picture the
land of the globe 113 a flexible area in a state of alow but inces-
sant change; the changes consisting of low undulations wliich
creep over the surface so aa to elevate and depress limited por-
tions in succession witiiout perceptibly affecting their nearly
horizontal posilion, and also of intense lateral compression,
supposed to be produced by parlinl subsidence along certain
lines of weakness in the earth's crust, tiie effect of which is to
cnimple the strata and force up certain areas in great contorted
masses, whiuh, wheu carved out liy siibaerial denudation into
peaks and valleys, constitute oiir great mountain systems.' In
this way every part of a continent may agaiu and again have
snnk beneath the sea, and yet as a whole may never have ceased
to exist as a continent or a vast continental archipelago. And
as subsidence will always be accompanied by deposition, piles
of marine strata many thousand feet tliick may have been
formed in a sea which was never very deep, by means of a slow
depression either continnous or intermittent, or through alter-
nate subsidences and elevations, each of moderate amount.
Supposed Oceanic Formationa; the Orifjuk of Chalk. — There
' Pioreseor Dunn points oiil llinl llie regions nlik'li. nfler lung iinilvrgoiitg aabsiil-
enre, nnJ ncciimuinling rust \it\e» of eedimenlnry deiioaiiR, liave hpen elevuled iutu
■nuunltiin -ranges, liave tiierab; become itilT nnil unyieliliiig, nnd tbal the next de-
(ireuion nnd Bubiec|uent agibeiivnl will lie Bitunteil on one ur [be olbor side of il;
n[id he ahows ibitt in North Antnicn ibU is ibu cnw niih all llio mountnins of the
tmnioNTi; geological funnntionB. Ilius, ileprcasiont anil clevBlions of extreme ilow-
IW4, bill often of rnsl nmount, have oocunwl aiicceuirelj in realricled nt^cent arens ;
nnd tlie effect bu been to bring each poition In auccewiion beneiiih tbe occnn, but nl-
uays bonlereJ on one or Iwlh lidn \>j ilie temoindor of tbe continent, fmin tbe den-
udnlion of wliicb the deinsita are formed which, on the siibacqaaiit npheaTol, bccoiM
ii-rnNgcj (" MnnnnI of Geology," r J ed., p. 7r>!).
Chap. VI.] GEOGKArHlCAL AND GEOLOGICAL CHANGES. 85
seems very good reason to believe that few, if any, of the rocks
known to geologists correspond exactly to the deposits now
forming at the bottom of our great oceans. The white oceanic
mud, or Globigerina ooze, found in all the great oceans at depths
varying from 250 to nearly 3000 fathoms, and almost constant-
ly in depths under 2000 fathoms, has, however, been supposed
to be an exception, and to correspond exactly to our white and
gray chalk. Hence some naturalists have maintained that there
has probably been one continuous formation of chalk in the
Atlantic from the Cretaceous epoch to the present day. This
view has been adopted chiefly on account of the similarity of
the minute organisms found to compose a considerable portion
of both deposits, more especially the pelagic foraminifera, of
which several species of Globigerina appear to be identical in
the chalk and the modern Atlantic mud. Other extremely mi-
nute organisms, whose nature is doubtful, called coccoliths and
discoliths, are also found in both formations, while there is a
considerable general resemblance between the higher forms of
life. SirWyville Thomson tells us that "sponges are abundant
in both, and the recent chalk-mud has yielded a largo number
of examples of the group Porifera vitrea, which find their near-
est representatives among the Ventriculites of the white chalk.
The echinoderm fauna of the deeper parts of the.Atlantic basin
is very characteristic, and yields an assemblage of forms which
represent in a remarkable degree the corresponding group in
the white chalk. Species of the genus Cidaris are numerous;
some remarkable flexible forms of the Diademidae seem to ap-
proach Echinothuria." * Now, as some explanation of the ori-
gin of chalk had long been desired by geologists, it is not sur-
prising that the amount of resemblance shown to exist between
it and some kinds of oceanic mud should have been at once
seized npon, and the conclusion arrived at that chalk is a deep-
sea oceanic formation exactly analogous to that which has been
shown to cover large areas of the Atlantic, Pacific, and South-
ern oceans.
But there are several objections to this view which seem fatal
^Natttre, Vol IL, p. 297.
86 ISLAND LIFE. [Part L
to its acceptance. In the first place, no specimens of Globigerina
ooze from the deep ocean-bed yet examined agree even approx-
imately with clialk in chemical composition, only containing
from 44 to 79 per cent, of carbonate of lime, with from 5 to 11
per cent, of silica, and from 8 to 33 per cent, of alumina and
oxide of iron.* Chalk, on the other hand, contains usually from
94 to 99 per cent, of carbonate of lime, and a very minute quan-
tity of alumina and silica. This large proportion of carbonate
of lime implies some other source of this mineral, and it is prob-
ably to be found in the excessively fine mud produced by the
decomposition and denudation of coral reefs. Mr. Dana, the
geologist of the United States Exploring Expedition, found in
the elevated coral reef of Oahu, one of the Sandwich Islands,
a deposit closely re^mbling chalk in color, texture, etc. ; while
in several growing reefs a similar formation of modern chalk,
undistinguishable from the ancient, was observed.* Sir Charles
> Sir W. Thomson, ** Voyage of the Challenger,*' Vd. IL, p. 374.
' The following is the analysis of the chnlk at Oahu :
Carbonate of lime 92.800 per cent.
Carbonate of magnesia 2.385 *'
Alumina 0.250 **
Oxide of iron 0.543 **
Silica 0.750 "
rhosphoric nciU and fluorine 2.113 **
Water and loss 1.148 **
This chalk consists simply of comminuted corals and shells of the reef. It has
been examined microscopically and found to bo destitute of the minute organisms
abounding in the chnlk of England (** Geology of the United States Exploring Ex-
pedition," p. 150).
This absence of Globigerinoc is a local phenomenon. They arc quite absent in the
Arafiira Se^i, and no Globigerina ooze was fuund in any of the enclosed sens of the
Pacific; but with these exceptions the Globigerina; **are really found all over the
bottom of the ocean ** (Murray on "Oceanic Deposits," Proceedings of the Royal So-
ciety, Vol. XXIV., p. 523).
The above analysis shows a far closer resemblance to chalk th.an that of the Glo-
bigerina ooze of the Atlantic, four specimens of which, given by Sir W. Thomson
("Voyage of the Cliallenger," Vol. II., Appendix, pp. 374-376, Nos. 9, 10, 11, and
12), from the mid-Atlantic, show the following ])roi)ortions :
Carbonate of lime 43.93 to 70.17 per cent.
Carbonate of magnesia 1.40 to 2.58 **
Alnmina and oxide of iron 0.00? to 32.98 **
Silica 4.G0 to 11.23 **
Chap. VI.] GEOGRAnilCAL AND GEOLOGICAL CHANGES. 87
Lyell well remarks that the pure calcareous mud produced by
the decomposition of the shelly coverings of mollusca and zoo-
phytes would be much lighter than argillaceous or arenaceous
mud, and being thus transported to greater distances would be
completely separated from all impurities.
Now the GlobigerinoB have been shown by the CJiaUenger
explorations to abound in all moderately warm seas ; living both
at the surface, at various depths in the water, and at the bot-
tom. It was long thought that they were surface-dwellers only,
and that their dead tests sank to the bottom, producing the Glo-
big6rina ooze in those areas where other deposits were absent or
scanty. But the examination of the whole of the dredgings and
surface-gatherings of the Challenger by Mr. H. B. Brady has led
him to a different conclusion ; for he finds numerous forms at the
bottom quite distinct from those which inhabit the surface, while,
when the same species live both at surface and bottom, the lat-
ter are always larger and have thicker and stronger cell-walls.
This view is also supported by the fact that in many stations
not far from our own shores Globigerinje are abundant in bot-
tom dredgings, but arc never found on the surface in the tow-
In addition to tho above, there is n qitnntity of insoluble residue consisting of sronll
particles of sanidinc, nugite, hornblende, and magnetite, supposed to be the product
of rolcanic dust or ashes carried either in the air or by ocean currents. This volcanic
matter amounts to from 4. GO to 8.33 per cent, of the Globigerina ooze of the mid-
Atlantic, where it seems to be always present; and the small proportion of similar
matter in true chalk is another proof that its origin is difTerenr, and that it was de-
posited far more rapidly than the oceanic ooze.
The following analysis of chalk by Mr. D. Forbes will show the difference between
the two formations :
Gray Chnlk. White Chalk.
Folkestone, Shoreham,
Carbonate of lime 94.09 98.40
Carbonate of mngnesia 0.31 0.08
Alumina and phosphoric acid a trace 0.42
('hloiide of sodium 1.29
Insoluble debris 3. 6 1 1.10
(From Quarterly Journal of the Geological Society^ Vol. XX VII.)
Tiie large proportion of carbonate of lime, and t)ie very small quantity of silica,
alumina, and in.soliible debris, at once distinguish true chalk from the Globigerina
ooze of tlic deep ocean- bed.
ISI.AND LIFE.
[PjhiL
iiig-nets.' Tliese orgftnisiiis tiien exist almost universally where
the waters are pure and are not too cold, and they would Jiatii-
riiDy abound inoeC where the difiasion of carbonate of lime both
ill Buspeiision and eolation afforded them an abundant Bupply
of material for their shelly coverings. Dr. Wallich believes that
they flourish best where the warm watera of the Gulf Sti-eaiu
bring organic matter from which they derive nutriment, since
they are wholly wanting in the eonrso of the arctic current be-
tween Greenland and Labrador. Ur. Carpenter also assures us
that thoy are rigorously liuiitcd to warm areas.
Now, with regard to the depth at which oiip chalk was formed,
we Lave evidence of sevei-al distinct kinds to show that it was
not pi-ofoiindly oceanic. Mr. J. Murray, in the Report already
referred to, says, " The Globigerina oozes which we get in shal-
low water resemble tlic chalk mnch more than tliose in deeper
water, say over 1000 fathoms."' This is important and weighty
evidence, and it is supported in a striking manner by the nature
of the moiluEcnn fauna of the chalk. Mr. Gwyn Jeffries, one
of our greatest authorities on shells, who has himself dredged
largely both in deep and shallow water, and who has no theory
to support, has carefully examined tliis question. Taking the
whole scries of genera which arc found in the Chalk formation,
seventy-one in uuuibcr, he declares that they are all compara-
tively shallow-water forms, many living at depths not exceeding
forty to fifty fathoms, while some are confined to etiU shallower
waters. Even more important is the fact that the genera espe-
cially characteristic of the deep Atlantic ooze — Leda, Verticor-
din, Nelera, and the Bulla fnmily^are either very rare or en-
tirely wanting in the ancient Cretaceous deposits,'
Let us now see how the various facts already adduced will
enable us to esplaiu the peculiar characteristics of the Chalk
formation. Sir Charles Lyelt tells ns that "pure Chalk, of
nearly uniform aspect and composition, is met with in a north-
' "Koios on Reliculnrinn ltliUopo(ln,"iii Microtcopicai JoMmul, Vul, XIX., N
feriflii, p. 81.
' Proendinti of the Royi-t SecUlf, Vol. XVI V., p. 532-
* Sea I'lvtiiteniiiil AdJieis in Sect. D of liiilisli Associiuion ni I'lj-mouili, 1877
CUAP.VI.] GEOGUAPHICAL AND GEOLOGICAL CHANGES. 89
west and southeast direction, from the north of Ireland to the
Crimea, a distance of about 1140 geographical miles; and in an
opposite direction it extends from the south of Sweden to the
south of Bordeaux, a distance of about 840 geographical miles."
This marks the extreme limits within which true chalk is found,
though it is by no means continuous. It probably implies, how-
ever, the existence across Central Europe of a sea somewhat
larger than the Mediterranean. It may have been much larger,
because this pure chalk formation would only be formed at a
considerable distance from land, or in areas where there was no
other shore - deposit. This sea was probably bounded on the
north by the old Scandinavian highlands, extending to Northern
Germany and Northwestern liussia, where Palaeozoic and an-
cient Secondary rocks have a wide extension, though now par-
tially concealed by late Tertiary deposits ; while on the south it
appears to have been limited by land extending through Aus-
tria, South Germany, and the South of France, as shown in the
map of Central Europe during the Cretaceous period in Profess-
or lleer's "Primeval World of Switzerland," p. 175. To the
north the sea may have had an outlet to the Arctic Ocean be-
tween the Ural range and Finland. South of the Alps there
was probably another sea, which may have communicated with
the northern one just described, and there was also a narrow
strait across Switzerland, north of the Alps, but, as might be ex-
pected, in this only marls, clays, sandstones, and limestones were
deposited instead of true chalk. It is also a suggestive fact that
both above and below the true chalk, in almost all the countries
where it occurs, are extensive deposits of marls, clays', and even
pure sands and sandstones, characterized by the same general
types of fossil remains as the chalk itself. These beds imply
the vicinity of land, and this is even more clearly proved by
the occurrence, both in the Upper and Lower Cretaceous, of de-
posits containing the remains of land plants in abundance, indi-
cating a rich and varied flora.
Now all these facts are totally opposed to the idea of any-
thing like oceanic conditions having prevailed in Europe during
the Cretaceous period ; but it is quite consistent with the exist-
ence of a great Mediterranean sea of considerable depth in its
90
ISLAND LIFE.
tPAl
central portions, and ocoiipj'ing, either at one or successive peri-
ods, tlio whole urea of tlie Cretaceous formation. We may also
note that the Maestriclit beds in Belgium and the Faxiie chalk
in Denmnrk are both highly coralline, the latter being, in fact,
as completely composed of corals as a modern conil reef; so that
we have hero a clear indication of the sonrce w-lience the white
ciilcareoua mud was derived which forms the basis of chalk. If
we suppose that during this period the comparatively shallow
eedrbottom between Scandinavia and Greenland was elevated,
forming a land connection between these countries, the result
wonld be that a large portion of the Gulf Stream would be di-
verted into the inland European sea, and would bring with it
that abundance of Globigerinte and other foraininifera which
form such an important constituent of chalk. This sea was
probably bordered with islands and coral reefs; and if no very
large rivers flowed into it, we should have all the conditions for
the production of the true chalk, as well as tlio other niemlrcrs
of the Cretaceous formation. The products of the denudation
of its shores and islands would form the %'arious sandstones,
marls, and clays which would be deposited almost wholly within
a few miles of its coasts; while the great central sea, perhaps at
no time more than a few thousand feet deep, would receive only
the impalpable mud of tl^e coral reefs and the constantly falling
tests of foraminifera. Tliese wonld embed and preserve for bs
the numerous cchinoderms, sponges, and niollusca which lived
upon the bottom, tho fishes and turtles which swnm in its
waters, and sometimes the winged reptiles that flew overhead.
Tiio abundance of ammonites and other ccphalopods in the
Chalk is another indication that the water in which they live<l
was not very deep, since Dr. S. P. Woodward ttiinks that these
organisms were limited to a depth of about thirty fathoms.
Tho best example of the modern formation of chalk is per-
hape to be found on the coasts of subtropical North America,
as described in the following passage:
"The observations of Ponrtales show that the steep banks of
Bahama are covered with soft white llme-umd. The limo-bot-
tom, which consists almost entirely of Polytlmlamia, covers in
greater depths the entire channel of Florida. This formation
Chap. VI.] GEOGRAPHICAL AND GEOLOGICAL CHANGES. 91
extends without interruption over the whole bed of the Gulf
Stream in the Gulf of Mexico, and is continued along the At-
lantic coast of America. The commonest genera met with in
this deposit are Globigerina, Eotalia cultrata, in large numbei's,
several Textilariee, Marginuliuse, etc. Besides these, small free
corals, Alcj'onidae, Ophiuiw, MoUusca, Crustacea, small fishes,
etc., are found living in these depths. The whole sea-bottom
appears to be covered with a vast deposit of white chalk still in
formation." *
There is yet another consideration which seems to have been
altogether overlooked by those who suppose that a deep and
open island-studded ocean occupied the place of Europe in Cre-
taceous times. No fact is more certain than the considerable
break, indicative of a great lapse of time, intervening between
the Cretaceous and Tertiary formations. A few deposits of in-
termediate age have indeed been found, but these have been
generally allocated either with the Chalk or the Eocene, leaving
the gap almost as pronounced as before. Now, what does this
gap mean ? It implies that when the deposition of the various
Cretaceous beds of Europe came to an end, they were raised
above the sea-level and subject to extensive denudation, and
that for a long but unknown period no extensive portion of
what is now European land was below the sea-level. It was
only when this period terminated that large areas in several
parts of Europe became submerged and received the earliest
Tertiary deposits known as Eocene. If, therefore, Europe at
the close of the Cretaceous period was generally identical with
what it is now, and perhaps even more extensive, it is absurd to
suppose that it was all, or nearly all, under water during that
period ; or, in fact, that any part of it was submerged except
those areas on which we actually find Cretaceous deposits, or
where we have good reason to believe they have existed.
The several considerations now adduced are, I think, suflBcient
to show that the view put forth by some naturalists (and which
has met with a somewhat hasty acceptance by geologists) that
our white chalk is an oceanic formation strictly comparable
> Geological Magazine, 1871, p. 42G.
92
ISLAND LIFE.
[T*n* I.
wUli tliHt now foniiing at <Ioptlts of a thousand fatlioiiis and ii|j-
waivis ill llic centre o£ tlie Atlantic, gives a totally eiToneous
idea of the actual condition of Europe during tliat period. In-
stead of lieing a wide ocean, ivitli a few scattered islands, corn-
parable to some parts of t!ie Pacific, it formed as truly a portion
of the great nortliern continent as it does now, although the in-
land seas of that epoch may have heen more extensive and more
numerous than they are at the pi-esent day."
J^resh^oater and Shore Di'ponits as Proving iite Pcmumciice
of Continctite. — The view here maintained, that all known ma-
rine deposits have been formed near the coasts of continents and
islantla, and that our actual continents have been in continuons
existence under variously modified forms during the whole
period of known geological history, is further supported by an-
other and totally distinct series of facts. In almost every period
of geology, and in all the continents which have been well ex-
amined, there are found lacustrine, estuarine, or shoro deposits,
containing the remains of land animals or plants, thus demon-
etrating the continuous existence of extensive land areas on or
adjoining the sites of our present continents. Beginning with
the Miocene, or Middle Tertiary, period, we have such deposits
with remains of land animals or plants in Devonshire and Soot-
land, in France, Switzerland, Germany, Croatia, Vienna, Greece.
North India, Central India, Burinah, North America (both cast
and west of the Kocky Mountiiins), Greenland, and other parts
of the arctic regions. In the older Eocene period similar for-
' [ii liblecinre on " fiooginpliicnl Evolii(ion"(whithwnapi[llishednfic!rlhogteiiicr
pni'l of iliU clinpior hnJ b«eii nriileii), I'mfcaaor Goikie ex|iress«« rient in coropleie
nccordnnco with tliosB liere ndiiwiileJ. He »»]■», "Tbo nexi long era, tlie (Jrein-
cooio, tvot morn reninrkable luralow ■ccumiil.ition of rock tinJci tlio am ttinn for the
fornitlinn of neiv Iniid. During Ilmt time the AlUntic ieiil its naicrs ni^roM iho
whole of tCuropa nnd into Abiii. But lliey ncre probubl}' nunhcra more tliuti n fen*
hunilrcJ fcol doop orar ih« sito of oiir coiiliiient, even at llieir dwpwt pun. L'lion
ilieir bollotn ihore gntliered n \mi mass of cnkareoua niud, compoEcd in grenl pni'l
orforaniinifeni, corals, «chiiiodern», nr>J moUiisks. Uur Kngliuli chnlki vrliivb ranges
ncrosa ilia Monb of Krnni^a, IlelKinm. Denninrk, and Ihe Norlli of Gernuiny, reprc-
wnu n poriiuii of tli« dspodu of ihnt un-Hoor." Tlio weigtir}' aiidiorit;' of iIis Di-
rector of llie (ieological Surrey of Sculluiid mny p«rlinpi cutiM lamc geologitis la
tnoiliry tbeir \ii?w« as la tha d«cp.«ea origin of clialk, wlio would liure ireaied any
iitguincnls nclrnnccd by myself n* not woriliy of coniiJcmlion.
Chap. VI.] GEOGRAPHICAL AND GEOLOGICAL CHANGES. 93
mations are widely spread in the South of England, in France,
and to an enormous extent on the central plateau of North
America ; while in the Eastern States, from Maryland to Ala-
bama, there are extensive marine deposits of the same age,
which, from the abundance of fossil remains of a large cetacean
(Zeuglodon), must have been formed in shallow gulfs or estua-
ries where these huge animals were stranded. Going back to
the Cretaceous formation, we have the same indications of per-
sisting lands in the rich plant-beds of Aix-la-Chapelle and a few
other localities on the Continent, as well as in coniferous fruits
from the Gault of Folkestone ; while in North America Creta-
ceous plant -beds occur in New Jersey, Alabama, Kansas, the
sources of the Missouri, the Kocky Mountains from New Mex-
ico to the Arctic Ocean, Alaska, British Columbia, California,
and in Greenland and Spitzbergen ; while birds and land rep-
tiles are found in the Cretaceous deposits of Colorado and other
Western districts. Fresh -water deposits of this age are also
found on the coast of Brazil. In the lower part of this forma-
tion we have the fresh-water Wealden deposits of England, ex-
tending into France, Hanover, and Westphalia. In the older
Oolite or Jurassic formation we have abundant proofs of con-
tinental conditions in the fresh-water and " dirt "-beds of the
Purbccks, in the south of England, with plants, insects, and
mammals ; the Bavarian lithographic stone, with fossil birds
and insects; the earlier "forest marble" of Wiltshire, with rip-
ple-marks, wood, and broken shells, indicative of an extensive
beach ; the Stonesfield slate, with plants, insects, and marsupials ;
and the Oolitic coal of Yorkshire and Sutherlandshire. Beds
of the same age occur in the Kocky Mountains of North Amer-
ica, containing abundance of Dinosaurians and other reptiles,
among which is the Atlantosaurus, the largest land-animal ever
known to have existed. Professor O. C. Mai-sh describes it as
having been between fifty and sixty feet long, and when stand-
ing erect at least thirty feet high ! * Such monsters could hardly
have been developed except in an extensive land area. A- small
' " Introduction nnd Succession of Vertebrate Life in Americn/'by Professor O. C.
Marsh. Reprinted from the Popular Science Monthly^ March, April, 1S78.
94
ISLAND LIFE.
[Part I.
mammal, Dryolestes, liaa been diBOOvered in the eauie deposits,
A rieli Jurassic flora has also beou found io East Siberia and
the Amoor valley. Tlie older Triassic deposits nre very exlen-
eively developed in Auierlca, and both in the Connecticut val-
ley and the lloeky Mountains show tracks or remains of land
reptiles, Hill phibians, and mammalia; white coal-fields of the same
age in Virginia and Carolina produce abundance of plants.
Here, too, is found the ancient mammal Microlestes, of Wiir-
temberg, with the ferns, conifers, and Labyrinthodonts of the
Bmiter Sandstone in Germany; while the beds of rock-salt in
this formation, both in England and in many parts of the Con-
tinent, could only have been formed in hiland seas or lakes, and
thns etjually demonstrate continental conditions.
We now pass into the oldest or Palieozoic fonnations, but
Jind no diminution in the proofs of continental conditions. The
Permian formation has a rich flora often producing coal in Eng-
land, France, Saxony, Tliuringia, Silesia, and Eastern Ilusein.
Coal-fields of the same ago occur iii Ohio, in North America. In
tlie still more ancient Carboniferous formation we find the most
remarkable proofs of the existence of our present continents at
that remote epoch, in the wonderfid extension of coal-beds in
all the known continents. Wo find them in Ireland, England,
and Scotland; in France, Spain, Belgium, Saxony, Prussia, Bo-
hemia, Hungary, Sweden, Spitzbergen, Siberia, liussia, Greece,
Turkey, and Persia; in many parts of continental India; cxten-
eivoly in China ; and in Australia, Tasmania, and New Zealand.
In North America there are immense coal-fields in Nova Scotia
and Now Brunswick, from Pennsylvania southward to Alabama,
in Indiana and Illinois, and in Missouri ; .ind there is also a true
coal formation in South Brazil. This wonderfully wide distri-
bution of coal, implying a^ it does a rich vegetation and exten-
sive land areas, carries hack the proof of the persistence and
general identity of our continents to a period so remote that
none of the higher animal types had probably Iteen developed.
But we can go eveu further hack than this, to the preceding
Devonian formation, which was almost certainly an inland de-
posit often containing remains of fresh-water shells, plants, and
even insects; while Professor Ramsay believes tliat he has
Chap. VI.] GEOGRAPHICAL AND GEOLOGICAL CHANGES. 95
found " sun-cracks and rain-pittings " in the Longmynd beds of
the still earlier Cambrian formation.' If now, in addition to
the body of evidence here adduced, we take into consideration
the fresh-water deposits that still remain to be discovered, and
those extensive areas where they have been destroyed by denu-
dation, or remain deeply covered up by later marine or volcanic
formations, we cannot but be struck by the abounding proofs of
the permanence of the great features of land and sea as they
now exist ; and we shall see how utterly gratuitous, and how
entirely opposed to all the evidence at our command, are the
hypothetical continents bridging over the deep oceans, by the
help of which it is so often attempted to cut the Gordian knot
presented by some anomalous fact in geographical distribution.
Oceanic Islands as Indications of the Permanence of Conti-
nents and Oceans, — Coming to the question from the other side,
Mr. Darwin has adduced an argument of considerable weight in
favor of the permanence of the great oceans. He says (" Origin
of Species,'* 6th ed., p. 288), " Looking to existing oceans, which
are thrice as extensive as the land, we see them studded with
many islands ; but hardly one truly oceanic island (with the ex-
ception of New Zealand, if this can be called a truly oceanic
island) is as yet known to afford even a fragment of any Palse-
ozoic or Secondary formation. Hence we may perhai>8 infer
that during the Palaeozoic and Secondary periods neither conti-
nents nor continental islands existed where our oceans now ex-
tend ; for had they existed. Palaeozoic and Secondary formations
would in all probability have been accumulated from sediment
derived from their wear and tear; and these would have been
at least partially upheaved by the oscillations of level which
must have intervened during these enormously long periods. If,
then, we may infer anything from these facts, we may infer that
where our oceans now extend, oceans have extended from the
remotest period of which we have any record ; and, on the other
hand, that where continents now exist large tracts of land have
existed, subjected, no doubt, to great oscillations of level, since
the Cambrian period." This argument standing by itself has
1 ((
Plnsicnl Geography nnd Geology of Great Bntnin,"5th ctl., p. 61.
96 ISLAND LIFK. [Pant I.
not rec-eivef! tlie attention it deserves, liut coming in snpport of
the long scries of facta of an altogether distinct nature, going to
show tlie permanence of continents, the cnimilativc effect of the
whole must, I think, bo admitted to be irresistible."
General Stability of Continents ■with Constant Change of Form.
— It will be observed that the very same evidence which has
been adduced to prove the general stability and permanence of
onr continental areas aleo goes to prove that they liave been
subjected to wonderful and repeated changes in detail. Every
square mile of their surface has been again ami again under
water, sonietimcs a few linndrt;d feet deep, sonietimea perhaps
several thousands. Lakes and inland seas have been formed,
Lave been filled up with sediment, and been subsequently raised
into hills or even mountains. Aniisi of the sea have existed
crossing the continents in various directioue, and thus completely
isolating the divided portions for varying intervala. Seas liave
been changed into deserts, nnd deserts into seas. Volcanoes
have grown into mountains, have been degraded and sunk be-
neath the ocean, have been covered with sedimentary deposits,
' Of liiia it Una been iho cuaiom to qnnlfl llie lo-cBlled " riilgo " Joivn ilie conlie
of the Ailnniic at indiFniing an cxieiisivc niicipnt liin J. ICren I'rofoMor Jiidd mlopi*
llito view. Tar he aprnka tX iho gieitt bell of Tertinry rulcunocB "uiiicli extended
iliroiigli Greenlnnd. Iceltind. ihe Fiiroe lolnnds, llie Ilcbridei, Irelnnd. Coniml Prance,
■he Ilnrinn IVninsuU, tlic Aiarc«, Mndoii'o, Cnnnrieii, Cii]ie de Verd I*Iiind», At-
ceiiaioii, St. Helena, and Trison d'Acunlia, and wliit'h conaliluted. pa slionn br llie
rei^nt sounding* of H. M. S. CktdUtigtr, a mnunlpin-i-nnee compamble in iia exient,
elevation, anj volranic cluirncier niili the Andes of Sonlh Amcricn" (Get/)ogiatl
Mag., I8T(, p. 71). On exntnininK the diagram of the Atlantic Ocean i(i the
CkallfKi/tr Beporla, No. T. n cnnsidernble part of ihii ridge ia found to he mora
then IIHK) fnihoma (1ee]i, wliile ilio )ioriion cidleJ the " Connecting Kidge" eecniR to
be dne in gmrt to the detHMita cnrried oul by Ilia river Amnton. In the nci^ibor-
hood of the Atorea, Bl. Fanl'e Bucks, Aiccnslon, and Tiitlan d'Acnnha nre coniid-
erable arcim viirviiig fiom 1200 lo IliOO fnthoma deep, wliile the reit of ttie ridge ia
niually 1800 or HKM) riitlionia. The ahollower wnter ia no doubt due lo Tolennic m|<-
heAval and the accnniulnlicin of volcanic ejoeiion*, nnd there may be many other
dec]ily tDbmHrEeil old volcanoen on the ridges but ihnt it ever formed a i:hnin of
fnonnlsini "rompamble in clevniion with the Andei" there eeema not n particle of
evidence tu prcivc. It i*. hon-ever, probable that iliia riJge indicates Iho former ex-
inlence of looie ronaidcrnblo Altanlic iiluD da, wliicli will aerve lo explain Iho preaence
uf afew ideiilicnl gencrn. nnd even H[>ccies. of plnnta andiitaecM in ATricnnnd South
Amerira. while the main body of the buna nnd flora of Iheae Ino contiaenti re-
muiiia nidlcn.ly dialiocL
Chap. VI.] GEOGRAPHICAL AND GEOLOGICAL CHANGES. 97
and again raised up into mountain-ranges ; while other moun-
tains have been formed by the upraised coral reefs of inland
seas. The mountains of one period have disappeared by denu-
dation or subsidence, while the mountains of the succeeding
period have been rising from beneath the waves. The valleys,
the ravines, and the mountain-peaks have been carved out and
filled up again ; and all the vegetable forms which clothe the
earth and furnish food for the various classes of animals have
been completely changed again and again.
Effect of Continental Changes on the Distribution of Animals,
— It is impossible to exaggerate, or even adequately to conceive,
the effect of these endless mutations on the animal world.
Slowly but surely the whole population of living things must
have been driven backward and forward from east to west, or
from north to south, from one side of a continent or a hemi-
sphere to the other. Owing to the remarkable continuity of all
the land masses, animals and plants must have often been com-
pelled to migrate into other continents, where in the struggle
for existence under new conditions many would succumb ; while
such as were able to survive would constitute those wide-spread
groups whose distribution often puzzles us. Owing to the re-
peated isolation of portions of continents for long periods, spe-
cial forms of life would have time to be developed, which, when
again brought into competition with the fauna from which they
had been separated, would cause fresh struggles of ever-increas-
ing complexity, and thus lead to the development and preser-
vation of every weapon, every habit, and every instinct, which
could in any way conduce to the safety and preservation of the
several species.
Changed Distribution Proved by the Extinct Animals of Dif-
ferent Epochs, — We thus find that while the inorganic world has
been in a state of continual though very gradual change, the
species of the organic world have also, been slowly changing in
fonn and in the localities they inhabit ; and the records of these
changes and these migrations are everywhere to be found, in
the actual distribution of the species no less than in the fossil
remains which are preserved in the rocks. Everywhere the
animals which have most recently become extinct resemble
7
ISL&NU LIVE.
[fABT I.
more or less closelj' those which now live in the Bame coniitrj ;
and where there are esceptions to the rule we can generally
trace theui to somo ciianjjed conditioos which have led to the
extinction of certain tjpes. Eut when we go a little further
bpj;k, to tho late or middle Tertiary deposits, we almost always
find, along with forms which might have been the ancestors of
soma now living, others which are now found only in remote
regions, and often in distinct continents— clear indications of
those extensive migrations wliich have ever been going on.
Every large ialand eontaine in ita animal inhabitants a recot'd of
the period when it was hist separated from the adjacent conti-
nent; while some portions of existing continents still show by
the comparative poverty and specialty of their animals that at
no distant epoch they wore cnt off by arms of the sea, and formed
islands. If the geological record were more perfect, or even if
wo had as good a knowledge of that record in all parts of tho
world as we have in Europe and North America, we conld arrive
at much more accui-ate results than we are able to do with our
present very imperfect knowledge of extinct forms of life ; but
even with our present scanty information we are able to throw
much light upon the past history of our globe and its inhabi-
tants, and can sketch out with confidence many of the changes
they must have undergone.
^ummart/ of Evithnee for the General Permanence of Conti-
nent and Oceans, — As this question of the permanence of our
continents lies at tho root of all our inquiries into tho past
citangee of the earth and its inhabitants, and as it is at present
completely ignored by many writers, and even by naturalists of
eminence, it will be well to summarize the various kinds of evi-
dence which go to establish it.' We know as a fact that all scdi-
' InarevicivofMr. Ren»lo'»"Clieiniail Deiiujniion anJ Gmlaglcnl TiniP,"iii .Vof-
urt (Octoher 3, IM70>, the \vril«r rem&cki ns folluwt: "One of llie ruiiii}' notion*
of suins DcieiitiRc itiinkeri meat* with no favor from Mr. Ilenile, ivhoM ^cclogiciil
knowledge is ptaclicnl ii« well n* ilieoreiicnl. Tliey coniiJar [Iml becniiae the older
rocki contain notbing like tlie present nnl clnyi, etc., of ilis ocenn-floor, tlie ocona
Imva always been in itieir present poaitionn. Mr. RciiiIb poinii oat iliet the flmi
jiroposilion ■■ not yet iiravnil ; nnd tlie Uintri lint ion of nnimnU nml pinnu, nnil the
fiict tlinl the hulk of the simtn On luiiJ me or nmiiiie origin, iirc upjiused ii> the liy-
Chap. VI.] GEOGRAPHICAL AND GEOLOGICAL CHANGES. 99
mentary deposits have been formed under water, but we also
know that they were largely formed in lakes or inland seas, or
near the coasts of continents or great islands, and that deposits
uniform in character and more than a hundred and fifty or
two hundred miles wide were rarely, if ever, formed at the same
time. The farther we go from the land, the less rapidly depo-
sition takes place ; hence the great bulk of all the strata must
have been formed near land. Some deposits are, it is true, con-
tinually forming in the midst of the great oceans; but these are
chiefly organic, and increase very slowly, and there is no proof
that any part of the series of known geological formations ex-
actly resembles them. Chalk, which is still believed to be such
a deposit by many naturalists, has been shown, by its contained
fossils, to be a comparatively shallow-water formation — that is,
one formed at a depth measured by hundreds rather than by
thousands of fathoms. The nature of the formations composing
all our continents also proves the continuity of those continents.
Everywhere we find clearly marked shore and estuarine depos-
its, showing that every part of the existing land has in turn been
on the sea-shore ; and we also find, in all periods, lacustrine for-
mations of considerable extent with remains of plants and land
animals, proving the existence of continents or extensive lands
in which such lakes or estuaries could be formed. These lacus-
trine deposits can be traced back through every period, from the
newer Tertiary to the Devonian and Cambrian, and in every
continent which has been geologically explored ; and thus com-
plete the proof that our continents have been in existence under
ever-changing forms throughout the whole of that enormous
lapse of time.
pothcsis." We must leave it to our reatlers to decide whether the "notion" devel-
oped in this chapter is ** funny," or whether such hnsty and superficinl arguments as
thoso here quoted from a "practical geologist" have any value as against the differ-
ent classes of facts, all pointing to an opposite conclusion, which have now been briefly
laid before them, supported as they are by the expressed opinion of so weighty an
authority as Professor Archibald Geikie, who, in the lecture already quoted, says,
" From all this evidence, we may legitimately conclude that the present land of the
globe, though formed in great measure of maiine formations, has never lain under
the deep sea ; but that its site must always have been near land. Even its thick
marine limestones are the deposits of comparniively shallow water."
100 ISLAND LIFE. [Pabt I.
On the side of the oceans we have also a great weight of evi-
dence in favor of their permanence and stability. In addition
to their enormous depths and great extent, and the circumstance
that the deposits now forming in them are distinct from any-
thing found upon the land surface, we have the extraordinary
fact that the countless islands scattered over their whole area
(with one or two exceptions only) never contain any Palseozoic
or Secondary rocks — that is, have not preserved any fragments
of the supposed ancient continents, nor of the deposits which
must have resulted from their denudation during the whole pe-
riod of their existence 1 The exceptions are New Zealand and
the Seychelles Islands, both situated near to continents, leaving
almost the whole of the vast areas of the Atlantic, Pacific, Indian,
and Southern oceans without a solitary relic of the great islands
or continents supposed to have sunk beneath their waves.
Chap. VIL] THE GLACIAL EPOCH. 101
CHAPTER VII.
CHANGES OF CLIMATE WHICH HAVE INFLUENCED THE DIS-
PERSAL OF ORGANISMS: THE GLACIAL EPOCH.
Proofs of the Recent Occurrence of a Glacial Epoch. — Moraines. — Travelled Blocks.
— Glacial Deposits of Scotland: the "Till." — Inferences from the Glacial Phe-
nomena of Scotland. — Glacial Phenomena of North America. — Effects of the Gla-
cial Epoch on Animal Life. — Warm and Cold Periods. — Palasontological Evidence
of Alternate Cold and Warm Periods. — Evidence of Interglacial Warm Periods
on the Continent and in North America. — Migrations and Extinctions of Organ-
isms Caused by the Glacial Epoch.
We liavo now to consider another set of physical revolutions
which have profoundly aflEected the whole organic world. Be-
sides the wonderful geological changes to which, as we have seen,
all continents have been exposed, and which must, with extreme
slowness, have brought about the greater features of the dispersal
of animals and plants throughout the world, there have been also a
long succession of climatal changes, which, though very slow and
gradual when measured by centuries, may have sometimes been
rapid as compared with the slow march of geological mutations.
These climatal changes may be divided into two classes, which
have been thought to be the opposite phases of the same great
phenomenon — cold or even glacial epochs in the temperate zones,
on the one hand ; and mild or even warm periods extending into
the arctic regions, on the other. The evidence for both these
changes having occurred is conclusive; and as they must be
taken account of whenever we endeavor to explain the past mi-
grations and actual distribution of the animal world, a brief out-
line of the more important facts and of the conclusions they lead
to must be here given.
Proofs of the Recent Occxtrreiice of a Gldcial Epoch, — The
phenomena that prove the recent occurrence of glacial epochs
in the temperate regions are exceedingly varied, and extend over
102 .'■:■..■*• ISLAND LIFE. [?»«■ I.
very wifhs-'areas. It will be well, therefore, to state, first, wliat
those Jireiiare as exhibited in onr own country, referring after-
Wftcde !o*Biiiiilar phenomena in other parts of the world,
. PeyJiaps the most striking of nil the evidences of glsciatioii
.*iO^*lio grooved, scratclied, or striated rocks. These occnr abiin-
//li^ntlj in Scothind, Cnmberland, and Nortli Wales, and no ra-
i.'tional explanation of them has ever been given except that tlicy
were formed hy glaciers. In many valleys — us, for instance, thai
of Llauherris, in North Wales^ — hondreds of examples may bo
seen, consisting of deep grooves several inches wide, smaller fur-
rows, and sti'iffi of extreme fineness wherever the rock is of suf-
ficiently close and liard tcxtnrc to receive sueh marks. These
grooves or seratches are often many jui-ds long ; thoy arc found
in the bod of the valley as well as liigli u]) on its sides, and tliey
arc almost all without exception in one general direction — that
of the valley itself, even thongh the particular sni-face they arc
upon sloiwa in aiiotlier direction. When the native covering of
tnrf is cleared away from tie rock, the grooves and striie are often
found in great perfection, and there is reason to believe that
such markings cover, or have once covered, a liirge part of the
snrface. Accompanying tlicse markings we find another hardly
less curious phenomenon, the rounding-off or planing-down of
the hardest rocks to a smooth undulating surface. Hard crys-
talline schists with tlieii- strata nearly vertical, and which one
would expect to find exposing jagged edges, ai-e found ground
off to a perfectly smootli but never to a flat surface. These
rounded surfaces are found not only on single rocks, but over
whole valleys and mountain-sides, and form what are termed
Toehea motitonnien, from their often having the appearance nt n
distance of slicep lying down.
Now these two phenomena are actually produced by existing
glftciei'B, while there is no other known or even conceivable cause
that could have produced them. Wlienever the Swiss glncioi's
i-etreat a little, as they sometimes do, the rocks in the bed of the
valley they have passed over are found to be rounded, grooved,
and striated just as are those of Wales and Scotland. The two
sets of phenomena are so exactly identical that no one who has
ever compared tiiem can doubt that they are due to the same
Cbap. YIL)
THE OL&CIAL ETOCH.
103
cauEes. Btit we have fm-ther and even mnro convincing evi-
dence. Glaciers produce many other effects besides these two ;
and whatever effects they produce in Switzerland, in Norway, or
in Greenland, we find examples of similar effects having been
prodneed in our own country. Tlie most striking of tliese are
moraines and travelled hloclcs.
J/rtraiVt^*.— Almost every existing glacier carries down with
it great masses of rock, stones, and earth, which fall on its sur-
face from tlie pi-ecipices and mountain -sIoihib which hem it in,
OP the rocky peaks which rise ahove it. As tlie glacier slowly
i downward, this dt'bris forms long lines on each side, or
on the centre whenever two glacier streams unite, and is depos-
ited at its termination in a linge mound called the terminal mo-
raine. The decrease of a glacier may often be traced by sncccs-
104
liiLAHD LIFE.
[I'Al
sivG old iiioriiiiies across tlie valley up which it lins retreated.
AVlieii once eoeti and c:;iiinined, those moraines can always be
distinguished almost at a glnnce. Their position is most re-
markable, Imviiig no apparent natural ixilation to the form of
the valley or the smTonnding slopes, so that they look like huge
earthworks formed by man fur purposes of defence. Tiieir
comijoeition is equally peculiar, consisting of a mixture of earth
and rocks of all £i>:c3, usually without any arrangement, the
rocks often being huge angular masses just as they had fallen
from the surrounding precipices, Some of these rock masses
often rest on the very lop of the moraine in positions where
no other natnrul foree but that of ice could have placed them.
Exactly similar mounds are found in tlic valleys of Nortli Wales
and Scotland, and always where the other evidences of ice-action
occur abundantly,
Trai'dlfd Blocks. — The phenomenon of travelled or perched
blocks is also a common one in all glacier countries, marking
out very claarly the former extent of the ice, "When a glacier
fills a lateral valley, its foot will sometimes ci'oss over the main
valley and abut against its opposite slope, and it will deposit
tlicre some portion of its terminal moraine. But in these cir-
cumstances the end of the glacier, not being confined laterally,
will spread out, and the moraine niatter will bo distributed over
a large surface, so that the only well-marked token of its presence
will bo the larger masses of rock that may have been brought
down. Sncli blocks are found abundantly in many of the dis-
tricts of our owu country where other marks of glaciation exist,
and they often rest on ridges or liilloeks over which the ice has
passed, these elevations consisting sometimes of loose material
and sometimes of rock dlffere^it from that oficldeh the blocks are
cojnposed. These arc called travelled blocks, and can almost al-
ways be traced to their source in one of the higher valleys from
which the glacier descended. Some of the must rcuDtrkable ex-
amples of such travelled blocks are to be found on tlie soutliern
elopes of the Jura. These consist of enormous angular blocks
of granite, gneiss, and other crystalline rocks quite foi-eign to
the Jura Mountains, but exactly agreeing with those of the Al-
pine range fifty miles sway across the groat central valley of
THE GLACUL EPOCH.
105
Switzerland. Oiio of the largest of these blocks \s forty feet in
diameter, and is Bitimted 900 feut above the level of the Lake of
NeufuhiTtel. These blocks have been proved by Swiss geologists
to have been brought bj the ancient glacier of the Rhone, which
was fed by the whole Alpine range, from Mont Blanc to tht.
Furka Pass. This glacier must have been many thousand feet
thick at the month of the Rhone volley near the head of the
Lake of Geneva, since it spread over the whole of the great val-
ley of Switserland, extending from <ieneva to JTeHfchatel, Berne,
and Solenre, and even on the tlanks of the Jnra reached a max-
imum height of 21)15 feet above the valley. Tlie numerous
blacks scattered over the Jura for a distance of about a hundred
ISLAND LIFE.
miles vary considerably in tlie material of iviiicli tliey are com-
poGed ; but they are fouTid to be each ti-aceable to a part of tho
Aljia corresponding to their position, on the theory that they
have been brought by a glacier spreading out from the Ghonc
valley. Tims, all the blocks situated to the east of a central
point G (see map) can be traced to the cnstcrn side of the lihone
valley {I e rf), while those found towards Geneva have all come
from the west side {p A). It is also very suggestive that the
highest bloeka on the Jura at G have come from the eastern
shoulder of Mont Blanc in the direct line A B F G. Here the
glacier would naturally preserve its greatest thickness, wliile, as
it spread out eastward and westward, it would become thinner.
We accordingly find that the travelled blocks on either side of
the central point become lower and lower, till near Soleure and
Geneva they are not more than about 500 feet above the valley.
The evidence is altogether 8o conclusive that, after personal ex-
amination of the distrit't in eouij>any with eminent Swiss geolo-
gists, Sir Charles Lyell gave up the view he had fii-st adopted—
that the blocks had been carried by ice during a period of sub-
inergcm^c— as altogether untenable'
The phenomena now described demonstrate a change of cli-
mate sufficient to cover all our higlier mountains with perpetual
snow, and fill the adjacent valleys wilh huge glaciers at least as
extensive ns those now found in Switzerland, But there are
other phenomena, best developed in tho northern part of onr
islands, which show that even this state of things was but the
concluding phase of the glacial period, which, during its maxi-
mum development, nmst have reduced the northern half of our
island to a condition only to be paralleled now in Greenland
and the antarctic regions. As few persons besides professed
geologists arc acquainted with the weight of evidence for this
gtaleineut, and as it is most important for our purpose to under-
stand the amount of the cUmatal changes the Northern Ilemi-
uphcre has undergone, I will endeavor to make the evidence in-
telligible, referring my readers for full details to Dr. James
Gcikie's descriptions and illustrations."
' "Amiqnily orM«n."*tli cil.,pp. 3<0-3i3,
' "Th« Great Ice Age nnd its Itolnlian to llio Aniiqniiv of Hon;" bv Jniura
Geikie, F.B.S. (IhiMcr* Co., 1«'4.)
Chap.VIL] the glacial EPOCH. 107
Glacial Deposits of Scotland: the ^^ TiU.^^ — Over almost all
the lowlands and in most of the highland valleys of Scotland
there are immense superficial deposits of clay, sand, gravel, or
drift, which can be traced more or less directly to glacial action.
Some of these are moraine matter, others are lacustrine deposits,
while others again have been formed or modified by the sea
during periods of submergence. But below them all, and often
resting directly on the rock surface, there are extensive layers of
a very tough clayey deposit known as " till." The " till " is very
tine in texture, very tenacious, and often of a rock-like hardness.
It is always full of stones, all of which are of rude form, but
with the angles rubbed off, and almost always covered with
scratches and strice often crossing each other in various direc-
tions. Sometimes the stones are so numerous that there seems
to be only just enough clay to unite them into a solid mass ; and
they are of all sizes, from mere grit up to rocks many feet in
diameter. The " till " is found chiefly in the low-lying districts,
where it covers extensive areas sometimes to a depth of a hun-
dred feet; while in the highlands it occurs in much smaller
patches, but in some of the broader valleys forms terraces which
have been cut through by the streams. Occasionally it is found
as high as 2000 feet above the sea, in hollows or hill-sides, where
it seems to have l>een protected from denudation.
The "till" is totally unstratified, and the rock surfaces on
which it almost always rests are invariably worn smooth, and
much grooved and striated when the rock is hard ; but when it
is soft or jointed it frequently shows a greatly broken surface.
Its color and texture, and the nature of the stones it contains, all
correspond to the character of the rock of the district where it
occurs, so that it is clearly a local formation. It is often found
underneath moraines, drift, and other late glacial deposits, but
never overlies them (except in special cases to be hereafter re-
ferred to), so that it is certainly an earlier deposit.
Throughout Scotland, where " till '* is found, the glacial striae,
perched blocks, roches moutomiies, and other marks of glacial
action occur very high up the mountains to at least 3000, and
often even to 3500, feet above the sea, while all lower hills and
mountains are rounded and grooved on their very summits; and
108
ISLAND LIFE.
[PmwL
these grooves alwaj's radiate outward from the liighest peaks
and ridgea towards the valleys or the eea.
Inferenoea front the Glucial Phenomena ofSooUand. — Xow all
these phenomena, taken together, vender it certain that the wliole
of Scotland waa uncc bnried in a vast eea of ice ont of wlticli
only the highest mountains raised their summits. There is ab-
solutely no escape from this conclusion ; for tho facts wliich lead
to it arc not local — fonnd only in one spot or one valley — but
general thronghout the entire length and breadth of Scotland;
and are, besides, supported by such a mass of detailed corrobo-
rative evidence as to amount to abeoluto demonstration. Tlie
weight of this vast ice -shoot, at least 3000 feet in maximum
thickness, and continually moving seaward with a slow gi-inding
motion like that of all existing glaciers, must liave ground down
the whole surface of the country, especially all the prominences,
leaving tho rounded rocka as well as the grooves and strife we
still sec marking the direction of its motion. All tho loose
stones and rock masses which lay ou the surface would be
pressed into the ice ; tlie harder blocks would servo as scratch-
ing and grinding tools, and wonld thus themselves become
rounded, scratched, and striated as we see tliem, while all the
softer masses would be ground up into impalpable mud along
with the material planed off the rocky projections of the coun-
try, leaving them in the condition of rodiea trtouCmitiecs.
The peculiar characters of tho " till," its fineness and tenacity,
correspond closely with tho flue matter which now issues from
under all glaciera, making the streams milky-while, yellow, or
brown, according to the nature of the rock. The scdinient from
sneli water is a fine unctuons sticky deposit, only needing press-
ure to form it into a tenacious clay ; and when " till " is exposed
to the action of water it dissolves into a similar soft sticky unct-
uous mud. Tho present ghiciers of the Alps, being confined to
valleys which carry off a largo quantity of drainage-water, lose
this mud perhaps as rapidly as it is formed ; but when the ice
covered the whole country there was comparatively littlo draiii-
ngo-water, and thus the mud and stones collected in vast com-
pact masses in all tho hollows, and especially in the lower flat
valleys, so that when the ice retreated tho whole country was
Chap.VIL] the glacial EPOCH. 109
more or less covered with it. It was then, no doubt, rapidly de-
nuded by rain and rivers ; but, as we have seen, great quantities
remain to the present day to tell the tale of its wonderful for-
mation.* There is good evidence that when the ice was at its
maximum it extended not only over the land, but far out to sea,
covering all the Scottish islands, and stretching in one connected
^ This view of the formation of ** till *' is that adopted by Dr. Geikie, and upheld
bj almost all the Scotch, Swiss, and Scandinavian geologists. The objection, how-
ever, is made by many eminent English geologists, including Mr. Searles V. Wood,
Jr., thnt mud ground off the rocks cannot remain beneath the ice, forming sheets of
groat thickness, because the glacier cannot at the same time grind down t^olid rock
and yet pass over the surface of soft mud and loose stones. But this difficulty will dis-
appear if we consider the numerous fluctuations in the glacier with increasing size,
and the additions it must have been constantly receiving as the ice from one valley
after another joined togetlier, and at Inst produced an ice-sheet covering the whole
country. The grinding power is the motion and pressure of the ice, and the pressure
will depend on its thickness. Now the points of maximum thickness must have often
changed their positions, and the result would be that the matter ground out in one
place would be forced into another place where the pressure was less. If there were
no lateral escape for the mud, it would necessarily support the ice over it, just as a
water-bed supports the person lying on it ; and when there was little drainage-water,
and the ice extended say twenty miles in every direction from a given part of a valley
where the ice was of less than the average thickness, the mud would necessarily ac-
cumulate at this part simply because there was no escape for it. Whenever the
pressure all round any area was greater than the pressure on that area, the debris of
the surrounding parts would be forced into it, and would even raise up the ice to give
it room. This is a necessary result of hydrostatic pressure. Duiing this process the
superfluous water would, no doubt, escape through Assures or pores of the ice, and
would leave the mud and stones in that excessively compressed and tenacious condi-
tion in which the **tiir* is found. The unequal thickness and pressure of the ice
above referred to would be a necessary consequence of the inequalities in the valleys,
now narrowing into gorges, now opening out into wide plains, and again n.-irrowed
lower down ; and it is just in these openings in the valleys that the *^ till " is said to
be found, and also in the lowlands, where an ice-sheet must have extended for many
miles in every direction. In these lowland valleys the **tiir* is both thickest and
most wide-spread, and this is what we might expect. At first, when the glaciers from
the mountains pushed out into these valleys, they would grind out the surface be-
neath them into hollows, and the drainage- water would carry away the debris. But
when they spread all over the surface from sea to sea, and there wns little or no
drainage- water compared to the enormous area covered with ice, the great bulk of
the de'bris must gather under the ice wherever the pressure was least, and the ice
would necessarily rise as it accumulated. Some of the mud would, no doubt, be forced
out along lines of least resistance to the sea, but the friction of the stone-charged
'* till " would be so enormous that it would be impossible for any large part of it to
be di^KMed ot in this way.
110
ISLAND LIFE.
[Pam I.
Gheet to Ireland and Wales, wliere all the evidences of glaciation
are as well marked a& in Scotlund, thongh the ice did not, of
course, attain quite so great a tliickness,"
It is evident that the change of cliuiato I'oquisito to jiroduco
sncli marvelloDs effects in tho Britisli Islea could uot have been
local, and we accoi-dingly find strikingly similar proofs that
Scandinavia and all Nortlicrn Kuropo have also been covered
with a hngo ice-sheet; while wc have already seen that a sim-
ilar gigantic glacier buried tho Alps, carrying granitic blocks to
the Jura, wlicro it deposited them at a height of 3150 feet above
the sea ; white to tlie south, in tho plains of Italy, the terminal
moraines left by the retreating glaciere have formed extensive
hills, those of Ivrea, the work of the great glacier from the Val
d'Aosta, being 15 miles across, and from 700 to 1500 feet high.
Glacial Pkentymena in North America. — In North America
the marks of glaciation ara even more extensive and striking
than in Europe, stretching over the whole of Canada and to the
south of tlio Great Lakes as far as latitude S'i", There is in all
these countries a wide-spread deposit like the " till" of Scotland,
produced by the grinding of the great ice-sheet when it was at
its maxlmnni thickness; and also extensive beds of moraine-
matter, true moraines, and travelled blocks, left by the glaciers
as they retreated towai-da tho mountains and finally withdrew
into tho upland valleys. There are also, both in Britain, Scan-
dhiavia, and North America, proofs of the submersion of tho
land beneath the sea to a depth of upwards of a thousand feet;
but this is ft subject we need not here enter upon, ns our special
object is to show the reality and amount of that wondei-ful and
comparatively recent change of climate termed the glacial epoch.
Many persons, even among scientific men, who have uot given
Ireland it prored by tlie
iniliii' ro ihRt in Smllnnil
ne rrnm Citmberlnnd mid
' Tlint ilie icc-slicci uoa continuoui froin Scoilund ci
glncial phenoDicna in the Isle of Man, vlier« "till" i
nboiintlfi, and rocki nre found in it which must hnve ec
Scodind. lu nell ns from Iho Nonh of Ireland. This would show (h&t glncien ftum
enrh of thuic districu readied the Iile of Man, where ihey met and flotred M>nlll-
wnrd doivn ihe Irish Ken. Ini-mnrkii are inieed over tho top* of (he munn'nini.
which are nearly S000fa«t high. (See "A Sketch of ilic GeoloKy of the Iile of
Mnn," by John Home, F.G.S., THntactioat iff the Edinburi/k Utohgkat Saeieti/,
Vol. U.,1'1. ill., 1874.)
Chap. VII.] THE GLACIAL EPOCH. Ill
much attention to the question look upon the whole subject of
the glacial epoch as a geological theory made to explain certain
phenomena which are otherwise a puzzle ; and they would not
be much surprised if they were some day told that it was all a
delusion, and that Mr. So-and-so had explained the whole thing
in a much more simple way. It is to prevent my readers being
imposed upon by any such statements or doubts that I have
given this very brief and imperfect outline of the nature, extent,
and completeness of the evidence on which the existence of the
glacial epoch depends. There is perhaps no great conclusion
in any science which rests upon a ^urer foundation than this;
and if we are to be guided by our reason at all in deducing the
unknown from the known, the past from the present, we cannot
refuse our assent to the reality of the glacial epoch of the
Northern Hemisphere in all its more important features.
Effects of the Glacial Epoch on Animal Life: Warm and
Cold Periods. — It is hardly necessary to point out what an im-
portant eflFect tills great climatal cycle must have had upon all
living things. When an icy mantle crept gradually over much
of the Northern Hemisphere till large portions of Europe and
North America were reduced to the condition of Greenland
now, the greater part of the animal life must have been driven
southward, causing a struggle for existence which must have led
to the extermination of many forms, and the migration of oth-
ers into new areas. But these eflFects must have been greatly
multiplied and intensified if, as there is very good reason to be-
lieve, the glacial epoch itself — or at least the earlier and later
phases of it — consisted of two or more alternations of warm and
cold periods.
The evidence that such was the case is very remarkable. The
" till," as we have seen, could only have been formed when the
country was entirely buried under a large ice-sheet of enormous
thickness, and when it must therefore have been, in all the parts
so covered, almost entirely destitute of animal and vegetable
life. But in several places in Scotland fine layers of sand and
gravel, with beds of peaty matter, have been found resting on
" till " and again covered by " till." Sometimes these interca-
lated beds are very thin, but in other cases they are twenty or
ISLAND IJ?E.
[P»»Tl.
thirty feet thick, and in them have been found remains of the
extinct ox, tlie Irish elk, the horse, reindeer, and mammoth.
Here we have evidence of two distinL-t periods of intense cold,
and an intervening milder period snfficiently prolonged for tlie
country to become covered with vegetation and stocked with
animal life. In some dietncte borings have proved the cxiet-
cnce of no less than fonr distinct formations of "till" sepamtcd
from each other bj beds of sand from two to twenty feet in
thickness.' Facta of a similar nature have been observed in
other piirts of our islands. In the East of England, Mr. Skertchly
(of the Geological Survey) enumerates four distinct boulder
elays with intervening deposits of gravels and sands.' Mr.
Searles V. Wood, Jr., classes the most recent (Ilesale) boulder
day as " postglacial ;" but he admits nn intervening wai-mer
period, chai-acterized by southern forms of mollusca and insects,
after which glacial eouditious again prevailed with northern
types of inol!usea.' Elsewhere bo says, "Looking at the pres-
ence of snob flnvtatile mollusca as C'l/reva Jiuniinalie and tJmo
lUtoralis. and of such mammalia as the hippopotamus and other
great pachyderms, and of such a littoml Lnsitanian fauna as
that of the Selsea bed, where it is mixed up with the remains of
some of those pachyderms, as well as of some other features, it
has seemed to mo that the climate of the earlier part of the
postglacial period in England was possibly even warmer than
our prci^^nt climate; and that it was succeeded by a refrigera-
tion eutlicieDtly severe to cause ice to form all round onr coasts,
and glaciers to accumulate in the valleys of the monntain dis-
tricts; and that tliis increased severity of climate was preceded
and partiiilly accompanied by a limited submergence, which no-
whore apiiarently exceeded 300 feet, and reached that amount
only ill the noitliern counties of England."* This decided ad-
• "The Gi'pni 1m Ako,"p. 1T7.
' Theso nic nnmod, in dcscemling orJer, Ileule lloiilder Clnr, I'uqile B<jtild<
Clnj, Cholk^ Boulder <?lnj, nnd Loner Boulder CIny, below wliidi is iliu Nomic
'"On lliB rlimate of the I'osiglniiiil reiiod," Crolnt/k-iit Mii'ja:inr, 1872, |i]
ir«, iGo.
* timhyiml Magntinr, 1871!, p. ^tHl.
Chap. VII.] THE GLACIAL EPOCH. 113
mission of au alternation of warm and cold climates since the
height of the glacial epoch by so cautious a geologist as Mr.
Wood is very important, as is his statement of an accompany-
ing depression of the land accompanying the increased cold, be-
cause many geologists maintain that a greater elevation of the
land is the true and sufficient explanation of glacial periods.
Further evidence of this alternation is found both in the Isle of
Man and in Ireland, where two distinct boulder claj's have been
described with intervening beds of gravels and sands.
PaXmontological Evidence of Alternate Cold and War?n Peri-
ods.— Especially suggestive of a period warmer than the pres-
ent, immediately following glacial conditions, is the occurrence
of the hippopotamus in caves, brick-earths, and gravels of palae-
olithic age. Entire skeletons of this animal have been found at
Leeds in a bed of dark-blue clay overlaid by gravel. Farther
north, at Kirkdale cave, in N. lat. 54° 15', remains of the hippo-
potamus occur abundantly along with those of the ox, elephant,
horse, and other quadrupeds, and with countless remains of the
hyenas which devoured them; while it has also been found* in
cave-deposits in Glamorganshire, at Durham Down, near Bris-
tol, and in the post-Pliocene drifts of Dorsetshire. It is impor-
tant to note that where it is associated with other mammals in
caves — which are hyena -dens, and not mere receptacles of
water-earned remains — these always imply a mild climate, the
elephant and rhinoceros found with it being species character-
istic of temperate latitudes {Elep/tas antiquus and Rhinoceros
heniiteechus). But when it occurs in gravels or in water-borne
cave-deposits it is sometimes associated with the mammoth, the
woolly rhinoceros, and the reindeer — animals which as certainly
imply a cold or even arctic climate. This diflFerence is intelli-
gible if we consider that the hyena, which carried the bones of
all these animals into the caves, is itself indicative of a mild
climate, and that there is nothing to cause the remains of ani-
mals of successive epochs to be intermingled in such caves. In
the gravels, however, it is very different. During the warm
periods the rivei*s would be inhabited by hippopotami, and the
adjacent plains by elephants and horses, and their remains would
be occasionally embedded in deposits formed during floods.
8
114
ISLAND LIFE.
[Pjii
But when the (.'old period came on. and these had passed south-
ward, the same nver-bnnks would be grazed \>y mammotliB and
reindeer whose remains would soinetinies intertningle witli those
of the aiiiuials which preceded tliem. It is to bo noted, also,
tliat in niauy of these river-deposits tliere are proofs of violent
iloods causing much rearrangement of materials, so that the
remains of the two periods would be tima still further inter-
mingled,'
The fact of the hippoiiotainus having lived at 54° N. lat. in
England, quite close to the time of the glacial epoch, is abso-
lutely incousistent with a mere gradual amelioration of climate
from that time till the present day. The immense quantity
of vegetable food which this creature requires implies a mild
and uniform climate with hardly any acvero winter; and no
theory that haa yet been suggested renders this possible except
that of alternate cold and warm periods during the glacial epoch
itself. In order that the hippopotamus could have reached
Yorkshire and retired again as the climate changed, we may
suppose it to have been a permanent inhabitant of the Lower
Khonc, between which river and the Khine there is an easy
communication by means of the Doubs and the 111, some of
whose tributaries approach within a mile or two of each other
about fifteen miles sontliwest of MiiUiausen, Theuce the pas-
sage would be easy down the Rhine into the great river which
then flowed up the bed of the North Sea, and thence up the
Ilumber and Ouse inio Yorkshire. By this route there would
be only one water -sited to cross, and this might probably
have been marshy ; but we may also suppose tlie animals to
liave ascended the Bristol Channel after passing round a long
extent of French and English coast (whith would tlien have
consisted of vast plains stretching far beyond the Scilly Isles),
in which case they would find an equally easy ]>aaeage over a
low water-slicd from the valley of the Avon to that of the Trent
and Yorkshire Ouse. A consideration of tlie long and circui-
tous journey required on any hypothesis will at once convince
' A, Tjlor, on "Qunieinary Gn
••/London, \W3, ]>i>. »3, D.'. (wood-ci
arttrly Jeitnial «f Gtalagiail Socitig
Chap. VII.] THE GLACIAL EPOCH. 115
ns tbat it could never have been made (as some have supposed)
annually during the short hot summer of the glacial period it-
self ; whereas the interglacial warm periods lasting several thou-
sand years would allow for the animals' gradual migration into
all suitable river valleys. Thus, the very existence of the hip-
popotamus in Yorkshire as well as in the South of England, in
close association with glacial conditions, must be held to be a
strong corroborative argument in favor of the reality of an in-
terglacial warm period.
Evidence of Interglacial Warm Periods on the Continent and
in North America. — Besides the evidence already adduced from
our own islands, many similar facts have been noted in other
countries. In Switzerland two glacial periods are distinctly rec-
ognized, between which was a warm period when vegetation
was so luxuriant as to form beds of lignite sufficiently thick to
be worked for coal. The plants found in these deposits are sim-
ilar to those now inhabiting Switzerland — pines, oaks, birches,
larch, etc. ; but numerous animal remains are also found, show-
ing that the country was then inhabited by an elephant {Ele-
phas antiquus), a rhinoceros {lihinoceros Etru8cus\ the urns
{Bo8 primigenius\ the red deer {Cervus elephas\ and the
cave-bear {Ursula spel<BU8)\ and there was also abundance of
insects.*
In Sweden also there are two " tills," the lower one having
been in places partly broken up and denuded before the upper
one was deposited, but no interglacial deposits have yet been
found. In North America more complete evidence has been
obtained. On the shores of Lake Ontario sections are exposed
showing three separate beds of " till" with intervening stratified
deposits, the lower one of which has yielded many plant re-
mains and fresh-water organisms. These deposits are seen to
extend continuously for more than nine miles, and the fossilif-
erous inter«:lacial beds attain a thickness of 140 feet. Similar
beds have been discovered near Cleveland, Ohio, consisting, first,
of " till " at the lake-level ; secondly, of about forty-eight feet of
sand and loam ; and, thirdly, of unstratitied "till " full of striated
» Hecr'8 " PrimaevalWorld of SwitzerUnd," VoL XL, pp. 14a-I68.
116
ISLAND LIFE.
stones, six feet tliic-k." On tlia other Bide of the continent, in
Dritish Columbia, Mr. G. M. Dawson, geologist to the North
American Bonndnry Commission, has discovered similar evi-
dence of two glaciations divided from eadi other by a warm
period.
This remarkable Beries of observations, spretid over so wide
an area, Beema to affoi-d ample proof that the glacial epoch did
not consist merely of one proCMJSs of dmiige from a temperate
to a cold and arctic climate, which, having reached a masinmm,
then passed slowly and completely away, but that there were
certainly two, and probably several more, alternations of arctic
and temperate climates.
It is evident, however, that if there have been, not two only,
but a series of such alternations of climate, we could not pos-
sibly expect to find more than the most slender indications of
them, becansc each sncceeding ice-sheet would necessarily grind
down or otherwise destroy much of the superficial deposits left
by its predecessors, while the torrents that must always liave ac-
companied the melting of these huge masses of ice would wash
away even such fragments as might have escaped the ice itself.
It is a fortunate thing, therefore, that wo should find any frag-
ments of these intcrglacial deposits containing animal and veg-
etable remains ; and, just as we should expect, the evidence they
afford seems to show that the later phase of the cold period was
less severe than the eaiiicr. Of such deposits ns were formed
on land during the eoming-on of the glacial epoch, when it was
continually increasing in severity, hardly a tiuee lias been pre-
served, because each succeeding extension of the ice, being
greater and thicker than llie last, destroyed what had gone bo-
fore it till the maximum was reached.
Mi'jra/irma aiid Extinction of Organisms Caused by the Gla-
cial Epoch. — Our last glacial epoch was accompanied by at least
two considerable Bubmergences and elevations of the land, and
there is some reason to think, as we have already explained, that
the two classes o( phenomena are connected ns cause and effect.
We can easily see how snch repeated submergences and eleva-
Chap. VII.] THE GLACIAL EPOCH. 117
tious would increase and aggravate the migrations and extinc-
tions that a glacial epoch is calculated to produce. "We can
therefore hardly fail to be right in attributing the wonderful
changes in animal and vegetable life that have occurred in Eu-
rope and North America between the Miocene period and the
present day, in part at least, to the two or more cold epochs that
have probably intervened. These changes consist, first, in the
extinction of a whole host of the higher animal forms; and, sec-
ondly, in a complete change of types due to extinction and emi-
gration, leading to a much greater diflFerence between the vege-
table and animal forms of the Eastern and Western hemispheres
than before existed. Many large and powerful mammalia lived
in our own country in Pliocene times, and apparently survived
a part of the glacial epoch ; but when it finally passed away, they
too had disappeared, some having become altogether extinct,
while others continued to exist in more southern lands. Amono:
the first class are the sabre-toothed tiger, the extinct Siberian
camel (Merycotherium), three species of elephant, two of rhinoc-
eros, a hippopotamus, two bears, five species of deer, and the gi-
gantic beaver ; among the latter are the hyena, bear, and lion,
which are considered to be only varieties of those which once
inhabited Britain. Down to Pliocene times the flora of Europe
was very similar to that which now prevails in Eastern Asia and
Eastern North America. Hundreds of species of trees and
shrubs of peculiar genera which still flourish in those countries
are now completely wanting in Europe ; and we have good rea-
son to believe that these were exterminated during the glacial pe-
riod, being cut off from a southern migration, first by the Alps,
and then by the Mediterranean ; whereas in Eastern America
and Asia the mountain-chains run in a north and south direc-
tion, and there is nothing to prevent the flora from having been
preserved by a southward migration into a milder region.
Our next two chaptei*8 will be devoted to a discussion of the
causes which brought about the glacial epoch, and that still more
extraordinary climatic phenomenon — the mild climate and luxu-
riant vegetation of the arctic zone. If my readers will follow
me with the care and attention so diflScult and interesting a prob-
118 ISLAND LIFE. [Part I.
leni requires and deserves, they will find that I have grappled
with all the facts which have to be accounted for, and offered
what I believe is the first complete and sufficient explanation of
them. The important influence of climatal changes on the dis-
persal of animals and plants is a sufficient justification for in-
troducing such a discussion into the present volume.
Chap.VIIL] the causes OF GLACIAL EPOCHS, 119
CHAPTER VIII.
THE CAUSES OF GLACIAL EPOCHS.
Various Suggested Causes. — Astronomical Causes of Changes of Climate. — Differ-
ence of Temperature Caused bj Varying Distance of the Sun. — Properties of Air
and Water, Snow and Ice, in Kelation to Climate. — Effects of Snow on Climate. —
High Land and Great Moisture Essential to the Initiation of a Glacial Epoch. —
Perpetual Snow nowhere Exists on Lowlands. — Conditions Determining the Pres-
ence or Absence of Perpetual Snow. — Efficiency of Astronomical Causes in Pro-
ducing Glaciation. — Action of Meteorological Causes in Intensifying Glaciation.
— Summary of Causes of Glaciation. — Effect of Clonds and Fog in Cutting off the
Sun*s Heat. — South Temperate America as Illustrating the Influence of Astronomi-
cal Causes on Climate. — Geo£p*aphical Changes, how far a Cause of Glaciation. —
Land Acting as a Bamer to Ocean Currents. — The Theory of Interglacial Peiiods
and their Probable Character. — Probable Effect of Winter in Aphelion on the Cli-
mate of Britain. — The Essential Principle of Climatal Change Restated. — Pi*ob-
able Date of the Last Glacial Epoch. — Changes of the Sea-level Dependent on
Glaciation. — The Planet Mars as Bearing ^n the Theory of Eccentricity as a
Cause of Glacial Epochs.
No less than seven diflEerent causes have been at various times
advanced to account for the glacial epoch and other changes of
climate which the geological record proves to have taken place.
These, as enumerated hy Mr. Searles V. Wood, Jr., are as fol-
lows :
1. A decrease in the original heat of our planet.
2. Changes in the obliquity of the ecliptic.
3. The combined eflFect of the precession of the equinoxes
and of the eccentricity of the earth's orbit.
4. Clianges in the distribution of land and water.
5. Changes in the position of the earth's axis of rotation.
6. A variation in the amount of heat radiated by the sun.
7. A variation in the temperature of space.
Of the above, causes 1 and 2 are undoubted realities ; but
it is now generally admitted that they are utterly inadequate
ISLAND LIFE.
tPi-tJ.
to produce the observed effects. Ouses 5, G, and 7 are all
purely liypotbetical ; for, though eucli changes may have occur-
ved, tlierc is no evidence that they have oecnrrod during geolog-
ical time, and it is, besides, certain that they would not, either
singly or combined, be adequate to explain the whole of the
phenomena. Thci-e remain cqubcb 3 and 4, which have the
advantage of being demouBtrated facts, and which are univer-
sally admitted to be eapabie of producing «oni* effect of the nat-
ure required, the only question being whether, cither alone or
in combination, they are adequate to produce all the observed
effects. It ia tlicrefore to these two causes that we shall con-
fine our inquiry, taking first those astronomical causes whose
complex and wide-reaching effects have been so admirably ex-
plained and discussed hy Dr. CtoII in numerous papers and in
his work " Climate and Time in tiieir Geological Relations."
Astronomical Causes of Changes ofClimatf. — The earth moves
in an elliptical orbit round the sun, which is situated in one of
the foci of the ellipse, so that tlie distance of the suu from ua
varies during the year to a considerable amount. Strange to
say, we are now three millions of miles nearer to the sun in win-
ter than in summer, while the reverse is the case in the South-
ern Hemisphere ; and this must have some effect in making our
northern winters less severe than those of the south temperate
zone. Hut the earth moves more rapidly in that part of its
orbit which is nearer to the sun, so that our winter is not only
milder, but several days shorter, than that of the Southern
Hemisphere. The distribution of land and sea and other local
causes prevent us from making any accurate estimate of the
effects due to these differences; but there can be no doubt that
if our winter were now !is long as our summer, and we were also
three million miles farther from the son at the former period,
a very decided difference of climate would result — our winter
would he colder and longer, our summer hotter and shorter.
Now tliere is a eombinalion of astronomical revolutions (the
precession of the equinoxes ami the motion of the aphelion)
which actually brings this change about every 10,500 years, so
that after this interval the condition of the two hemispheres is
reversed as i-egflrds nearness to the sun in sumnicr, and com-
Chap. VIIL] • THE CAUSES OF GLACIAL EPOCHS. 121
parative duration of summer and winter; and this change has
been going on throughout all geological periods. (See diagram.)
The influence of the present phase of precession is perhaps
seen in the great extension of the antarctic ice-fields, and the
existence of glaciers at the sea-level in the Southern Ilemisphere
in latitudes corresponding to that of England ; but it is not sup-
posed that similar effects would be produced with us at the
last cold period, 10,500 yeai*s ago, because we are exceptionally
favored by the Gulf Stream warming the whole North Atlantic
Ocean, and by the prevalence of westerly winds which convey
that warmth to our shores ; and also by the comparatively small
quantity of high land around the North Pole, which does not
N.HEMISPHERE WINTER IN APHELION S .HEMISPHCRC WMTER IN APHELION
GLACIAL EPOCH IN GLACIAL EPOCH IN
NJIEMISPHERC 8.HEMISPHERC
DIAGRAM 8H0WIN0 THE ALTERED POSITION OF THE POLES AT INTERVALS OF 10,500
YEARS PRODUCED BT THE PRECESSION OF THE EQUINOXES AND THE MOTION OF
THE APHELION; AND ITS EFFECT ON CLIMATE DURING A PERIOD OF IIIUH EC-
CENTRICITY.
encourage great accumulations of ice. But the amount of eccen-
tricity itself varies very largely, though very slowly, and it is
now nearly at a minimum. It also varies very irregularly ; but its
amount has been calculated for several million years back. Fifty
thousand years ago it was rather less than it is now ; but it then
increased, and when we come to a hundred thousand yeare ago,
there is a diflFerence of eight and a half millions of miles between
our distance from the sun in aphelion and perihelion (as the
most distant and nearest points of the earth's orbit are termed).
At a hundred and fifty thousand yeai-s back it had decreased
somewhat — to six millions of miles; but then it increased again,
till at two hundred thousand years ago it was ten and a quarter,
and at two hundred and ten thousand vears ten and a half, mill
ISLAND UFE.
[PjuwI.
ions of uiilea- By reference to tlio accompanying diagram, which
itidiidGS the last great period of eceentrioity, we tiud that for
the irumcusc period of a hundred and sixty thoiiEaud years
(commencing about eighty thousand years ago) the eccentricity
wiis very great, reaching a maximum of three and a half times
its present amount at almost the remotest part of this period, at
which time the length of summer in one hemisphere and of
winter in the other would be ncai'ly twenty-eight days iu excess.
rPROBULE DURATION OF TXE CLACIAL EPOCH^
Tlie ilark mid li^bt bands miiik ihe p)in»ei of |ireceuion, the dark Bhouing ilinrt
mild wintera, nnd tlis lieht Icing cold winten, ilie conti'i»t being grcnier aa the
ecMiitricit}^ IB liiRher. The lioiiioniAl dotted line mnrki llio present eccenlricitr.
'i'lie Hgares show ilie Rinximn and minima of eccenlriciij duiing ilie liist 3UO,000
jenrg Fiom Dr. Crolls laUen.
Now during all this time our position would cliange, as al>ove
described (and as indicated on the diagram), every ten thousand
five hundred years ; so that we should have iilteniate periods of
very long and cold winters with short hot sunnners, and short
mild winters with long cool Eumniers, In order to undorataiid
the important elleets which this would produce, we must ascer-
tain two things — first, what actual difference of temperature
would he caused by varying distiinces of the sun ; and, secondly,
what are the properties of snow and ice in regard to climate.
Diferenix tif Tewpei'ature Cuy«fi/ bi/ Vaci/itiff Di^taticfs qfth^
Sitn. — On this subject comparatively few persona have correct
Chap. VIII.] THE CAUSES OF GLACIAL EPOCHS. 123
ideas, owing to the unscientific manner in which wo reckon
heat by our thermometei*s. Our zero is thirty-two degrees be-
low the freezing-point of water, or, in the centigrade thermom-
eter, the freezing-point itself, both of which are equally mislead-
ing when applied to cosmical problems. If we say that the
mean temperature of a place is 50° F. or 10° C, these figures
tell us nothing of how much the sun warms that place, because
if the sun were withdrawn the temperature would fall far be-
low either of the zero-points. In the last arctic expedition a
tempemture of —74° F. was registered, or 106° below the freez-
ing-point of water ; and as at the same time the earth, at a depth
of two feet, was only —13° F. and the sea-water -f28° F., we
may be sure that even this intense cold was not near the possi-
ble minimum temperature. By various calculations and experi-
ments which cannot be entered upon here, it has been deter-
mined that the temperature of space, independent of solar (but
not of stellar) influence, is about —239° F., and physicists al-
most universally adopt this quantity in all estimates of cosmical
temperature. It follows that if the mean temperature of the
earth's surface at any time is 50° F., it is really warmed by the
sun to an amount measured by 50 + 239 = 289° F., which is
hence termed its absolute temperature. Now during the time
of the glacial epoch the greatest distance of the sun in winter
was 97^ millions of miles, whereas it is now, in winter, only 91
millions of miles. But the quantity of heat received from the
sun is inversely as the square of the distance, so that it would
then be in the proportion of 8281 to 9506 now, or nearly one
eighth less than its present amount. The mean temperature of
England in January is about 39° F., which equals 278° F. of ab-
solute temperature. But the above-named fraction of 278° is
36°, representing the amount which must be deducted to obtain
the January temperature during the glacial epoch, which will
therefore be 3° F. Our actual temperature at that time might,
however, have been very diiferent from this, because the tem-
perature of a place does not depend so much on the amount of
heat it receives directly from the sun as on the amount brought
to it or carried away from it by warm or cold winds. We often
have it bitterly cold in the middle of May when we are receiv-
ISLAND LIFE.
[PiBiL
i[ig as iinicSi sim lieat as many parts of the tropics, because we
get cold winds from the iceberg-ladeu North Atlantic, and this
partially neutralizes the effect of the eun. So wc often bave it
very mild in December if son tli westerly winds bring uB warm
moist nir from the Gulf Stream. Hut though the above method
does not give correct results for any one time or place, it is
more nearly correct for very large areaci, because all the sensible
surface heat which produces climates comes from the sun, and
its proportionate amount may be very nearly calculated in the
manner above described. We may therefore say, generally, that
during our iiortliorn winter, at t!ie time of the glacial epoclj,
the Northern Hemisphere was receiving bo much less heat from
the sun as to lower ils surface teinperatiii-e on an average about
35° F., while during tlie height of summer of the same period
it would be receiving so much more heat as would snffice to
raise its mean temperature abont 00* F. above what it is now.
The winter, however, would be long and the snuimer short, tlie
difference being twenty-six days.
We Iiavc here certainly a superabundant amonnt of cold in
winter to produce a glacial period,' especially as this cold would
' In a letier lo JVafunt of Oclober 30, 1 @T'J, the Itcv. O, FJ^^Iier mils ntCeniJon to n
resnlt an-ived nt by I'oulUat. that tlio lenipeiiitLii'e uliicli ihe miriuca of nie graunil
would OBsurao if the sun were exlinguialieil would L>e —138" F. iiisiend of —iSd" F.
If iliii corrected nmoaiil ncrc ntcd in our cnlcuin lions, ilio Jnnimr}' tcmperalura of
Enslnnd duving the gincini epoch would come out 17° F., and llii) Mr. Fialiei' tiiiiika
not low cnnDgh to canto nny cxireme iliffercnce from the present climnte. In thia
opinion, lioweTor, I unnot ngive wUh htin. On (he contrar}'. it would, I iliiuk, be
A relief to the theory wera tlic nroonnts of decrcnso of lamperilure in nioter nnd in-
crenw in summer rondei-od moid mudernte, litice nccording to llio ubuoI calculation
(which I have ndnpied) the dilTei-cncei nro unnctiesE^iirily great. I cniiuot, iliererore,
think that iliia tnodilieaiion of (lie lempemtnres. ihontd it be uliironiely proied to be
eon'«et (nhich in nitogeiher denied lit Dr. Croll), would be nny seiioua objeciioii In
the adoption of Dr. CroU'i theory of llic nslronomicnl nnd phiftical ciiu*ea of the
glHcial epoch.
The renaon of ihe increnie of ■nmmcr hent being CiO", while )be decnea«e of winter
cold is only 3u', is because our lummer is now btloa nnd onr winler aiiane the aver-
age. A large part of Uic W increase of lemperntin'e wouiil, no donbt, be lued up in
erapomting wiiter, so that there would be a much leu iiici-case of senniblc hem ;
while only n poiiion of iho 30" lonciing of lemjietniure in niiiier uould be nciunlly
prodnced, oHing lo eqnnlixing effect of winds nnd currents nnd ihe tloring-up of
hcnt bv Ihe cnitli nnd ocean.
Chap.VIIL] the causes OF GLACIAL EPOCHS. 125
be long continued ; but at the same time we sliould have almost
tropical heat in summer, although that season would be some-
what shorter. How, then, it may be asked, could such a climate
have the effect supposed? Would not the snow that fell in
winter be all melted by the excessively hot summer? In order
to answer tliis question, we must take account of certain proper-
ties of water and air, snow and ice, to which due weight has not
been given by writers on this subject.
Properties of Air and Water ^ Snow and Ice^ in Helation to
Climate. — The great aerial ocean which surrounds us has the
wonderful property of allowing the heat-i-ays from the sun to
pass through it without its being warmed by them ; but when
the earth is heated the air gets warmed by contact with it, and
also to a considerable extent by the heat radiated from the warm
earth, because, altliough pure dry air allows such dark heat-rays
to pass freely, yet the aqueous vapor and carbonic acid in the
air intercept and absorb them. But the air thus warmed by
the earth is in continual motion, owing to changes of density.
It rises up and flows off, while cooler air supplies its place ; and
thus heat can never accumulate in the atmosphere beyond a
very moderate degree, the excessive sun heat of the tropics being
much of it carried away to the upper atmosphere and radiated
into space. Water also is very mobile ; and although it receives
and stores up a great deal of heat, it is forever dispersing it over
the earth. The rain, which brings down a certain portion of
heat from the atmosphere, and which often absorbs heat from
the earth on which it falls, flows away in streams to the ocean ;
while the ocean itself, constantly impelled by the winds, forms
great currents, which carry off the surplus heated water of the
tropics to the temperate and even to the polar regions, while
colder water flows from the poles to ameliorate the heat of the
tropics. An immense quantity of sun heat is also used up in
evaporating water, and the vapor thus produced is conveyed by
tlie aerial currents to distant countries, where, on being con-
densed into rain, it gives up much of this heat to the earth and
atmosphere.
The power of water in carrying away heat is well exhibited
by the fact of the abnormally high temperature of arid deserts
ISLAND LIFE.
[Paw I.
and of very dry countries geiieriilly; while tlie still more pow-
erful influence of moving nir may be appreciated by cousider-
ing tlie effects of even our northern sun in heating a tightly
closed glass house to far above the temperature produced by the
vertical sun of the eqnator, wlicre the free air and abundance of
moisture exert their beneficial influence. Were it not for the
large proportion of the sun'a heat carried away by air and water,
the tropics would become uninhabitable furnaces; ae would, in-
deed, ajiy part of the earth where the fliin shone brightly throngh-
out a Buinmer's day.
We see, therefore, tliat the excess of lieat derived from the
snn at any place cannot be stored up to aii important amount
owing to the wonderful dispersing agency of air and water ; and
though some heat does penetrate the ground and ie stored up
there, this is so little in proportion to the whole amount re-
ceived, and the larger part of it is so soon given out from the
surface layers, that any surplus heat that may be thus preserved
during one snromer rarely or never remains in sufficient quanti-
ty to affect the temperature of the succeeding summer, so that
there is no such thing as an accnmulatioii of earth heat from
year to year. Unt though heat cannot, cold can be stored up
to an almost unlimited amount, owing to the peculiar property
water possesses of Incoming solid at a moderately low tempera-
ture ; and as this is a subject of the very greatest importance to
niir inquiry — the whole (question of the possibility of glacial
ppocha and warm periods depending on it — we must consider it
in some detail.
liffixi^ of Snmci on Climate. — Let ns, then, examine the very
diffei'cnt effects produced by water falling as a liqnid in the
form of rain, or as a solid in the form of snow, although the
two may not differ from each otiier more than two or three de-
grees in temperature. The rain, however much of it may fall,
runs off rapidly into streams and rivers, and soon reaches the
ocean. If cold, it cools the air and the earth somewhat while
passing tlirongh or over them, but produces no permanent effect
on temperature, because a few hours of sunshine restore to the
air or the eurfaec soil all the heat they had loRt. Ihit If snow
falls for a long lime, the effect, as wo all know, is very different,
Chap. VIII.] THE CAUSES OF GLACIAL EPOCHS. 127
because it has no mobility. It remains where it fell and becomes
compacted into a mass, and it then keeps the earth below it and
the air above at or near the freezing-point till it is all melted.
If the quantity is great, it may take days or weeks to melt ; and
if snow continues falling, it goes on accumulating all over the
surface of a country (which water cannot do), and may thus
form such a mass that the warmth of the w*hoIe succeeding sum-
mer may not be able to melt it. It then produces perpetual
enow, such as we find above a certain altitude on all the great
mountains of the globe ; and when this takes place cold is ren-
dered permanent, no amount of sun heat warming the air or the
earth much above the freezing-point. This is illustrated by the
often-quoted fact that at 80° N. lat. Captain Scoresby had the
pitch melted on one side of his ship by the heat of the sun,
while water was freezing on the other side owing to the coldness
of the air.
The quantity of heat required to melt ice or snow is very
great, as we all know by experience of the long time masses of
snow will remain unmelted even in warm weather. We shall,
however, be better able to appreciate the great eflfect this lias
upon climate by a few figures showing what this amount really
is. In order to melt one cubic foot of ice, as much heat is re-
quired as would heat a cubic foot of water from the freezing-
point to 176"^ F., or two cubic feet to 88"^ F. To melt a layer
of ice a foot thick will therefore use up as much heat as would
raise a layer of water two feet thick to the temperature of 88°
F. ; and the effect becomes still more easily understood if we es-
timate it as applied to air, for to melt a layer of ice only one and
a half inch thick would require as much heat as would raise a
stratum of air 800 feet thick from the freezing-point to the tropi-
cal heat of 88° F. ! We thus obtain a good idea, both of the won-
derful power of snow and ice in keeping down temperature, and
also of the reason why it requires so long a time to melt away,
and is able to go on accumulating to such an extent as to be-
come permanent. These properties would, however, be of no
avail if it were liquid, like water; hence it is the state of solid-
ity and almost complete immobility of ice that enables it to pro-
duce by its accumulation such extraordinary effects in physical
ISLAND LIFE.
[PillT J.
geograpiiy and in fliinate as we seo in tlie glaciers of Switzer-
land and the iue-capped iEitcrior of Ureonland.
High Land and G^renl Moisture Easential to t/te Initiation of
a Glacial Epoch. — Aiiotber point of great importance in con-
nection witli tliis subject is the fact that this permanent storing-
np of cold depends entirely on the annual ainonnt of snow-fall
in proportion to that of the sun and air heat, and not on the act-
ual cold of winter, or even on the average cold of the year. A
place may be intensely cold in winter and tnay Imve a short
arctic BUinnicr, yet, if so little snow falls that it is quickly melted
by the returning sun, there is nothing to prevent the summer
being hot and the earth producing a luxuriant vegetation. As
an example of this we have great forests in tiie extreme North
of Asia and America where the wintera are colder and the sum-
mers shorter than in Greenland, in lat. 62° N., or tiian in ileai-d
Island and South Georgia, both in lat. 63° S., in the Southern
Ocean, and almost wholly covered with perpetual snow and ice.
At the *' Jai'din" on the Mont Blanc range, above the line of
perpetual snow, a thermometer in an exposed situation marked
— 6° F. as the lowest winter temperature ; wJiile in many parts
of Siberia mereury freezes several weeks in winter, showing a
temperature below —40° F.; yet here the summers are hot, all
the snow disappears, and there is a luxuriant vegetation. Even
in the very highest latitudes reached by our last arctic exjiedi-
tion there is very little perpetual snow or ice, for Captain Nai-es
tells us that north of Hayes's Sound, in lat. 79° IS., the mountains
were remarkably free from ice-cap, while extensive tracts of
land were free from snow during summer, and covered with a
rich vegetation with abundance of bright flowers. The reason
of this is evidently the scanty snow-fall, which rendered it some-
times difficult to obtain enough to form shelter-banks around
the ships; and this was north of S0° N. lat,, wliere the sun
was absent for a hundred and forty two days.
Perpetual Snow nowhere Heists on Lowlands. — It is a very
remarkable and most suggestive fact that nowhere in the world
at the present time are there any cstcnsivo lowlands covered
with perpetual snow. The Tundras of Siberia and the barren
grounds of Nortli America are all clothed with some kind of
Chap. VIII.] THE CAUSES OF GLACIAL EPOCHS. 129
summer vegetation ; * and it is only where there are lofty moun-
tains or plateaus — as in Greenland, Spitzbergen, and Grinnell's
Land — that glaciers, accompanied by perpetual snow, cover the
country, and descend in places to the level of the sea. In the
antarctic regions there are extensive highlands and lofty moun-
tains, and these are everywhere exposed to the influence of moist
sea-air; and it is here, accordingly, that we find the nearest ap-
proach to a true ice-cap covering the whole circumference of
the antarctic continent, and forming a girdle of ice-cliffs which
almost everywhere descend to the sea. Such antarctic islands as
South Georgia, South Shetland, and Heard Island are often said
to have perpetual snow at sea-level ; but they arc all very moun-
tainous, and send down glaciers into the sea, and as they are
exposed to moist sea-air on every side, the precipitation, almost
all of which takes the form of snow even in summer, is of
course unusually large.
That high land in an area of great precipitation is the neces-
sary condition of glaciation is well shown by the general state
of the two polar areas at the present time. The northern part
of the north temperate zone is almost all land, mostly low but
with elevated borders ; while the polar area is, with the excep-
tion of Greenland and a few other considerable islands, almost
all water. In the Southern Hemisphere the temperate zone is
almost all water, while the polar area is almost all land, or is at
least enclosed by a ring of high and mountainous land. The
result is that in the north the polar area is free from any ac-
cumulation of permanent ice (except on the highlands of Green-
land and Grinnell's Land), while in the south a complete barrier
of ice of enormous thickness appears to surround the pole. Dr.
CroU shows, from the measured height of numerous antarctic
' In nil Account of Professor Nordenskjold's recent expedition round the nortiiern
const of Asiji. given in Nature, November 20, 1879, we have the following passage
fidly supporting the stnteroent in the text : ^' Along the whole coast, from the White
Sea to Behring Strait, no glacier was seen. During autumn the Siberian coast is
nearly free of ice and snow. There are no mountains covered all the year round
with snow, although some of them rise to a height of mora than two thousand feet."
It must be remembered thnt the north coast of Eastern Siberia is in the area of sup-
posed greatest winter cold on the globe.
9
icebergs {often miles in ieiigtli) that the ice-sbect from which
they are the hi-okeu outer Erngmcnts must be from a mile to a
railo and a half in thickness.' As this is the thickness of the
onter edge of the ice, it must he far thicker inland; and we
thus find that the antarctic continent is at this very time suf-
fering giaciation to quite as great an extent as we have i-caeon
to believe oceurrcd in the same latitudes of the Noithern llcni-
isjihcre during the last glacial epoch.
The accompanying diagrams show the comparative state of
the two polar areas both as regards the distribution of land and
Boa, and the extent of the ice-sheet and floating icebergs. The
nuidi greater quantity of ice at the south pole is nudoubteiily
due to tlie presence of a large extent of high land, which acta
«8 a condenser, and an unbroken eiirroundiug ocean, which af-
fords a constant supply of vapor; and the effect is intensified
by winter being there in aphelion, and thus several days longer
than with us, wliile the whole Southern Hemisphere is at that
time farther from the sun, niid tliei-efore receives less heat.
We see, however, that with less favorable conditions for the
production and accumulation of ice, Greenland is glaciated down
to lat. 01°. Wliat, then, would be the effect if the antarctic
continent, instead of being confined almost wholly within the
south polar circle, were to extend in one or two great moun-
tainous promontoriea far into the temperate zone? The com-
paratively small Heard Island, in S. lat. 53°, is even now glaci-
ated down to the sea. What would be its condition were it a
northerly extension of a lofty antarctic continent? We may
be quite sure that giaciation wonid then be far more severe, and
that an ice-sheet corresponding to that of Greenland might ex-
tend to beyond the parallel of 50' S. lat. Even this is probably
too low an estimate, for on tbe west coast of New itealand, in S.
lat. 43° 35', a ghieier even now descends to witiiin seven hundred
and five feet of the sea-level; and if those islands were the
northern extension of an niitaretic continent, we may be pretty
sure that they would be nearly in the icc-covcred condition of
Greenland, although situated in the hititiidc of Marseilles.
' "On llie Glarial Epoch," by James Croll, Onlm/Kiil Mnijariai, Juir, Aiigiui,
13S
ISLAKD LIFU;.
[Paw I.
Vonditi-jns JJderminiiuj the Presence or Ahaence of PerpeUtal
finoio. — It is clear, then, tliat the vicinity of a sea or ocean to
supply moisture, together with high land to serve as a condenser
of that nioistnre into snow, are the prime essentials of a great
accninnhition of ice ; and it is fully in accordance with this view
that wc find the most undouhtcd al^ua of extensive glaciation in
the west of Eui-ope and the east of North Anieriea, both washed
by thu Atlantic, and both having ahundancQ of high land to
condense the nioistnre which it supplies, Witliout these condi-
tions cold alone, however great, can prodnce no glacial epoch.
This is strikingly shown by the fact that in the very coldest
portions of the iwo northern continents — Eastern yiberia and
the northwestern shores of Iliideon's Baj' — there in no peren-
nial covering of snow or ice whatever. No less remarkable is
the coincidence of the districts of greatest glaciation with those
of greatest rainfall at the present time. Looking at a raiu-map
of the British Isles, we see that the greatest area of excessive
rainfall is the Highlands of Scotland, then follow the West of
Ireland, Wales, and tlie North of England; and tiiese were gla-
ciated pretty nearly in proportion to the area of country over
which there is an abundant supply of moisture. So in Enrope,
the Alps and the Scandinaviau mountains have excessive rain-
fall, and have been areas of excessive glaciation, while the Ui-al
and Caucasian mountains, with less rain, never seem to Jiave been
proportionally glaciated. In North Anienca the eastern coast
has an abundant rainfall, and New England with Kortheastern
Canada seems to have been the source of much of the glaciation
of that continent.'
' '' Tlie genoml obMnce of recenl mniUx of gliii-inl action in l^siam I'iurotM ii ucll
knnwn ; iinil ilia seriei of cliangis w1ii<:li linvo been lo neEl traced nnd dcscri1i«il by
I'roftWHir Kinbii an occarring in iIiohi distritti M«nii lo leave no room for lliose pe-
tiodicnl extension* of ' iee-cn)ni' will) wliicli louie nntliors in thin couniry lincc nmnsed
tliemsclvu tind Ilic^ir rsntlera, Mr. Canijibell, wliusa alnlily lo nvognite llie phjsicut
evidence ofglneien will Bcnrcely be qamtioiioil, lindii <|uiie ibe samo absence of tlie
liraof of nieniive irc-nelinn in Nurtli Ainericn woilwnrd of ilie meridimi of Clii-
I'dtEo" lI'i'DfvfMir J.W. Jiidd, in Utologieat U'lgatinr, 1676, p. 61)9).
The uiDie author nuies the diminnlion of mnrlut of ice-action on gainic eoititnrd in
■he Alp« ; and llie Altai Monnlnini fnr in Centml Aiia ihow no aigni of linviiig been
largely glnciolcd. West of the Rocliy Mountnina, honever, in tlie tjierm Nevndn nnd
the const rangci fiii'thernonh, lignit of cxlcniivc old glncieri ngnin nppenr; nil wliieh
CiiAP.VlIl.] THE CAUSES OF GLACIAL EPOCHS. 133
The reason why no accumulation of enow or ice ever takes
place on arctic lowlands is explained by the observations of
Lieutenant Payer of tlie Austrian Polar Expedition, who found
that during the short arctic summer of the highest latitudes the
ice-fields diminished four feet in thickness under the infiuence
of the sun and wind. To replace this would require a precipi-
tation of snow equivalent to about forty-five inches of rain, an
amount which rarely occurs in lowlands out of the tropics. In
Siberia, within and near the Arctic Circle, about six feet of snow
covers the country all the winter and spring, and is not sensibly
diminished by the powerful sun so long as northerly winds keep
the air below the freezing-point and occasional snow-storms oc-
cur. But early in June the wind usually changes to southerly,
probably the southwestern anti-trades overcoming the north-
ern inflow ; and under its influence the snow all disappears in a
few days, and the vegetable kingdom bursts into full luxuriance.
This is very important as showing the impotence of mere sun
heat to get rid of a thick mass of snow so long as the air re-
mains cold, while currents of warm air are in the highest degree
effective. If, Iiowever, they are not of suflBciently high tem-
perature, or do not last long enough to melt the snow, they are
likely to increase it from the quantity of moisture they bring
with them, which will be condensed into snow by coming into
contact with the frozen surface. We may therefore expect the
transition from perpetual snow to a luxuriant arctic vegetation
to be very abrupt, depending as it must on a few degrees more
or less in the summer temperature of the air; and this is quite
in accordance with the fact of corn ripening by the sides of Al-
pine glaciers.
tJjjicieixcy of Astronomical Causes in Produ<:ing Glaciation. —
Having now collected a suflicient body of facts, let us endeavor
to ascertain what would be the state to which the Northern
IIemisi)here would be reduced by a high degree of eccentricity
and a winter in aphelion. When the glacial epoch is supposed
to have been at its maximum, about 210,000 years ago, the cc-
phenomena are strikingly in accordfince with the theory here advocated of the abso-
hue dejMindence of glaciation on abundant rainfall and elevated snow condensers and
accnmuhitors.
ISU?fD LIFE.
[pABTt
ceiitricity was more than three times as gi'cat as it is now ; and,
according to Dr. Croll's calculations, tliu midwinter temperature
of the Northern Hemisphere would have been lowered 36" F.,
wliiie the winter Iiulf of the year would have been twenty-six
days longer than the Bumnier half. This would bring the Jan-
uary mean tcmiiei-atiire of England and Scotland almost down
to zero, or about 30° F, of frost, a winter climate correspond-
ing to that of Labrador, or the coast of Greenland on the Arctic
Circle. But we niust remember that tlie summer would be just
as much hotter than it is now, and tlio problem to be solved is,
whether the snow that fell in winter would accumulate to such
an extent that it ■would not be melted in summer, and so go on
increasing year by year till it covered the whole of Scotland, Ire-
land, and Wales, and much of England. Dr.Crall and Dr. Geikic
answer without hesitation that it would. Sir Charles Lyell main-
tained that it would only do so when geographical conditions
were favorable; while the late Mr. Belt has argued that eccen-
tricity alone would not produce the effect unless aided by in-
creased obliquity of the ecliptic, which, by extending the width
of the polar regions, would increase the duration and severity of
the winter to such an extent that snow and ice would be formed
in the arctic and autai-ctic regions at the same time, whether
the winter were in perihelion or aphelion.
The problem we have now to solve is a very difficult one, be-
cause we have no case at all parallel to it from wliicli we can
draw direct ooncluaiona. It is, however, clear, from the various
considerations wo have already adduced, that the increased cold
of winter, when the eccentricity was great and tlie sun in aphe-
lion during ttiat season, would not of itself produce a glacial
epoch unless the amount of vapor supplied for condensation was
also exceptionally great. The greatest quantity of snow falls in
the arctic regions in summer and autumn, and with us the great-
est quantity of rain falls in the antunmal months. It seems
probable, then, that in all northern lands glaciation would com-
mence when autumn occuned in aphelion. All the rain which
falls on our mountains at that season would then fall as snow,
and, being further increased by the snow of winter, would form
accumulations which the summer might not be iible to melt.
Chap. VIII.] THE CAUSES OF GLACIAL EPOCHS. 135
As time went on, and the aphelion occurred in winter, the per-
ennial snow on the mountains would have accumulated to such
an extent as to chill the spring and summer vapors, so that tliey
too would fall as snow, and thus increase the amount of deposi-
tion; but it is probable that tin's would never in our latitude
have been sufficient to produce glaciation, were it not for a se-
ries of climatal reactions which tend still further to increase the
production of snow.
Action of Meteorological Causes w Intensifying Glaciation, —
The trade-winds owe their existence to the great difference be-
tween the temperature of the equator and that of the poles, which
causes a constant flow of air towards the equator. The strength
of this flow depends on the diflference of temperature and the ex-
tent of the cooled and heated masses of air, and this effect is now
greatest between the south pole and the equator, owing to the
much greater accumulation of ice in the antarctic regions. The
consequence is that the southeast trades are stronger than the
northeast, the neutral zone or belt of calms between them not
being on the equator, but several degrees to the north of it. But
just in proportion to the strength of the trade -winds is the
strength of the anti - trades, that is, the upper return current
wliich carries the warm moisture-laden air of the tropics towards
the poles, descending in the temperate zone as west and south-
west winds. These are now strongest in the Southern Hemi-
sphere, and, passing everywhere over a wide ocean, they supply
the moisture necessary to produce the enormous quantity of
snow which falls in the antarctic area. During the period we
are now discussing, however, this state of things would have
been partially reversed. The south polar area, having its winter
in perihelion, would probably have had less ice, while the north
temperate and arctic regions would have been largely ice-clad ;
and the northeast trades would therefore be stronger than they
are now. The southwesterly anti-trades would also be stronger
in the same proportion, and would bring with them a greatly in-
creased quantity of moisture, which is the prime necessity to
produce a condition of glaciation.
But this is only one half of the effect that would be produced,
for the increased force of the trades sets up another action which
136 ISLAND LIFE. [I'Anr I.
still further helps on tlic aecnniulation of snow and ice. It is
now generally admitted tliat wo owe nmcli of our mild climate
and our comparative freedom fi-oiii snow to tlie iuflneuce of the
Gnlf Stream, which also ameliorates the climate of Scandinavia
and Spitsbergen, as shown by the reiiiavkable northward cnrva-
tnro of the iaotherniid lines, so that Drontheim, in N, lat. 62", has
the aamo mean temperature as Halifax (Nova Scotia), in N. lat.
45°. The quantity of heat now brought info the North Atlantic
by the Gulf Stream dei>ends mainly on the superior strength of
the southeast trades. When the northeast trades were the more
powerful, the Gnlf Strcaui would certainly be of mucli less mag-
nitude and velocity ; while it is possible, as Dr. CroU thinks, that
a large portion of it might be diverted aouthward, owing to the
peculiar form of the east coast of South America, and so go to
Bwcli the Brazilian current and ameliorate the climate of the
Southern Hemisphere,
That effects of this nature would follow fram any increase of
the arctic and decrease of the Antarctic ice may he considered
certain ; and Dr. Crotl has clearly shown that in this case cause
and effect act and react on eaclt other in a remarkable way.
The increase of snow and ice in the Northern Hemisphere is the
cause of an increased supply of moisture being brought by the
more powerful anti-trades; and this greater supply of moisture
leads to an extension of the ice, which reacts in still further
increasing tlie supply of moisture. The same increase of snow
and ice, by causing the northeast to be stronger than tiie south-
east trade-winds, diminishes the force of the Gulf Stream, and
this diminution lowers tiic temperature of the North Atlantic
both in summer and winter, and thus helps on still further the
formation and perpetuation of the icy mantle. It must also be
remembered that these agencies are at the same time acting in
a reverse way in the Southern Hemisphere, diminishing the sup-
ply of the moisture carried by the anti-trades, and increasing
the tempcralure by means of uiorc powerful southward ocean
currents; and all this again reacts on the Northern Hemisphere,
increasing yet further the supply of moisture by the more pow-
erful aonthwcsterly winds, while still further lowering the tem-
perature by ttie eoutitward diversion of the Gulf Stream.
Chap. VIII.] THE CAUSES OF GLACIAL EPOCHS. 137
Summary of Principal Causes of Glaciation. — I have now
suflSciently answered the question why the short hot summer
would not melt the snow which accumulated during the long
cold winter. (produced by high eccentricity and winter in aphe-
lion), althougli the annual amount of heat received from tlie
sun was exactly the same as it is now, and equal in the two
hemispheres. It may be well, before going further, briefly to
summarize the essential causes of this apparent paradox. These
are — primarily, the fact that solar heat cannot be stored up, ow-
ing to its being continually carried away by air and water, while
cold can be so stored up, owing to the comparative immobility
of snow and ice ; and, in the second place, because the two great
heat-distributing agencies, the winds and the ocean currents, are
so affected by an increase of the snow and ice towards one pole
and its diminution towards the other as to help on the process
when it has once begun, and by their action and reaction pro-
duce a maximum of effect which, without tlieir aid, would be
altogether unattainable.
But even tliis does not exhaust the causes at work all tending
in one direction. Snow and ice reflect heat to a much greater
degree than does land or water. The heat, therefore, of the short
summer would have far less effect than is due fo its calculated
amount in melting the snow, because so much of it would be
lost by reflection. A portion of the reflected heat would, no
doubt, warm the vapor in the atmosphere ; but this heat would
l>e carried off to other parts of the eartli, while a considerable
portion of tlie whole would be lost in space. It must also be
remembered tliat an enormous quantity of heat is used up in
melting snow and ice, without raising its temperature; each
cubic foot of ice requiring as much heat to melt it as would
raise nearly six cubic feet of water 30° F. It has, however, been
argued that because when water is frozen it evolves just as much
heat as it requires to melt it again, there is no loss of heat on
the whole ; and, as this is adduced as a valid argument over and
over again in every criticism of Dr. Croll's theory, it may be
well to consider it a little more closely. In the act of freezing,
no doubt, water gives up some of its heat to the surrounding
air; but that air still remains below the freezing-pointy or freez-
[Pai
iDg would not take place. The lieat libeiatcil by freezing is,
til cref ore, what may be termed low-grade heat — Iieat incapable
of melting snow or ice; while the bent absorbed while ice or
SHOW is melting is high-grade beat, such rb Is capable of melt-
ing snow and supporting vegetable growth. Moreover, the low-
grade heat liberated in the formation of snow is usually libei-
atod high up in the atmosphero, wbei-c it may be carrietl off by
winds to more southern latitudes; while the beat absorbed in
molting the surface of snow and ice is absorbed close to the
earth, and is thus prevented from warming the lower atmosphere,
which is in contact with vegetation. The two phenomena, tbei-e-
fore, by no means counterbalauce or counteract each other, as it
is so constantly and superficially asserted that thoy do.
Effect ofClouda aiul Fog in Cutting off the iSuiCs Heat. — An-
other very important cause of diminution of heat during sum-
mer in a glaciated country would be the intervention of clonds
and fogs, wliieli would reflect or absorb a large proportion of
the sun heat and prevent it reaching the surface of the earth;
and such a cloudy atmosphere would be a necessary result of
large areas of high land covered with snow and ice. That such
a prevalence of fogs and cloud is an actual fact in all ice-clnd
countries hns been shown by Dp. Groll most conclusively, and
he has further shown that the existence of perpetual snow often
depends upon it. South Georgia, in the latitude of Yorkshire,
is alnioBt, and Sandwich Land, in the latitude of the North of
Scotland, is entirely, covered with perpetual snow; yet in their
eummer the sun is three million miles nearer the earth than it
is in our summer, and the heat actually received from tbu sun
must bo sufficient to raise the temperature 20° F. higher than
in the same latitudes in the Northern Jlemispliere, were the
conditions equal^nstead of which their summer temperature is
probably fully 20° lower. The chief cause of this can only bo
that the heat of the sun does not reach the surface of the earth ;
and that this is the fact is teetifled by all antarctic voyagers.
Danvin notes the cloudy sky and constant moisture of the soutli-
eni part of Chili, and in his remarks on the climate and pro-
ductions of the antaretic islands he says, "In the Southern
Ocean the winter is not so excessively euld, but the summer is
CuAP.VIIL] THE CAUSES OF GLACIAL EPOCHS. 139
far less hot (than in the north), for the clouded sky seldom allows
the sun to wa)*vi the ocean, itself a bad absorbent of heat ; and
lience the main temperature of the year, which regulates the
zone of perpetually congealed under-soil, is low." Sir James
Ross, Lieutenant Wilkes, and other antarctic voyagei*s speak of
the snow-storms, the absence of sunshine, and the freezing tem-
perature in the height of summer; and Dr. CroU shows that
this is a constant phenomenon accompanying the presence of
large masses of ice in every part of the world.*
In reply to the objections of a recent critic. Dr. Croll has
given a new proof of this important fact by comparing the
known amount of snow-fall with the equally well-known melt-
ing power of direct sun heat in diflferent latitudes. He says,
" The annual precipitation on Greenland in the form of snow
and rain, according to Dr. Kink, amounts to only twelve inches,
and two inches of this he considers is never melted, but is car-
ried away in tlie form of icebergs. The quantity of heat re-
ceived at the equator from sunrise to sunset, if none were cut
oflf by the atmosphere, would melt three and a third inches of
ice, or a hundred feet in a year. The quantity received between
latitude 60° and 80°, which is that of Greenland, is, according to
Meech, one half that received at the equator. The heat received
by Greenland from the sun, if none were cut oflf by the atmos-
phere, would therefore melt fifty feet of ice per annum, or fifty
times the amount of snow which falls on that continent. What,
then, cuts oflE the ninety-eight per cent, of the sun's heat ?" The
only possible answer is that it is the clouds and fog during a great
part of the summer, and reflection from the surface of the snow
and ice when these are absent.
South Temperate America as Illustrating the Influence of
Astrojiomi^^al Causes on Climate, — Those persons who still doubt
the effect of winter in aphelion with a high degree of eccentric-
ity in producing glaciation should consider how the condition
of south temperate America at the present day is explicable if
^ For numerous details and illustrations, see the paper *'0n Ocean Currents in
Relation to the Physical Theory of Secular Changes of Climate,*' in the Philosophical
Magazine y 1870.
ISLAND LIFE.
[Paui I.
tliey reject this agency. The line of perpetual snow in the
Southern Andes is so low as 6O00 feet in the same latitude as
tlie Pyrenees. In the latitude of the Swiss Alps, mountains only
6200 feet high [iroduco immense glaciers which descend to the
sea-Ievel ; wliile, in the latitude of Cumberland, mountains only
from 31)00 to iOOO feet hiyli have every valley filled with streams
of ice descending to the sea-coast and giving off abundance of
huge icebergs.' Here we have exactly the condition of things
to which England and Western Europe were subjected during
the latter portion of tlie glacial epoch, when every valley in
Wales, Cumberland, and Scotland liad its glacier; and to what
can this state of things be imputed if not to the fact that there
is now a moderate amount of eccentricity, and the winter of the
Southern Hemisphere is in aphelion? The mere geographical
position of the southern extremity of America does not seem
especially favorable to the production of such a state of glacia-
tion. The land narrows from the tropics southward, and ter-
minates altogether in about the latitude of Edinburgh; ttie
nionutaiuB are of moderate heiglit; while during summer the
fiitn is three millions of miles nearer, and tlie heat received from
it is equivalent to a rise of 20° F. as compai'ed with the same
season in the Northern Hemisphere. Tlie only important dif-
ferences are the open Southern Ocean, the longer and colder
winter, and the general low tempeniture caused by the south
polar ice. But the great accumulation of south polar ice is it-
self due to the great e.xtent of high land within tlio Antarctic
Circle acted upon by the long cold winter and furnislied with
moisture hy the surrounding wide ocean. These conditions of
high knd and open ocean we know did not prevail to so great
ail extent in the Northern Hemisphere during the glacial
epoch as they do in the Southern Hemisphere at the present
time ; but tlie other acting cause — the long cold winter — existed
in a far higher degree, owing to the eccentricity being about
three times as much as it is now. It is, so far as we know or
are justified in believing, the only efficient cause of glaciation
which was undoubtedly much more powerful at that time; and
mi. ilioWorlJ,"2d ed..ii[.. aH-2.11.
chap.vhi.] the causes of glacial epochs. 141
we are tliereforc compelled to accept it as the most probable
cause of the much greater glaciation which then prevailed.
Geographical ChangetSy how far a Cause of Glaciation, —
Messre. Croll and Geikie have both objected to the views of Sir
Charles Lyell as to the preponderating influence of the distribu-
tion of land and sea on climate ; and they maintain that if the
land were accumulated almost wholly in the equatorial regions,
the temperature of the earth's surface as a whole would be low-
ered, not raised, as Sir Charles Lyell maintained. The reason
given is that the land being heated heats the air, which rises and
thus gives off much of the heat to space, while the same area
covered with water would retain more of the heat, and by means
of currents carry it to other parts of the earth's surface. But
although the mean temperature of the whole earth might be
somewhat lowered by such a disposition of the land, there can
be little doubt that it would render all extremes of temperature
impossible, and that even during a period of high eccentricity
there would be no glacial epochs, and perhaps no such thing as
ice anywhere produced. This would result from there being no
land near the poles to retain snow, while the constant inter-
change of water by means of currents between the polar and
tropical regions would most likely prevent ice from ever form-
ing in the sea. On the other hand, were all the land accumulated
in the polar and temperate regions, there can be little doubt that
a state of almost i:>erpetual glaciation of much of the land would
result, notwithstanding that the whole earth should theoretically
be at a somewhat higher temperature. Two main causes would
bring about this glaciation. A very large area of elevated land
in high latitudes would act as a powerful 'condenser of the enor-
mous quantity of vapor produced by the whole of the equatorial
and much of the temperate regions being areas of evaporation,
and thus a greater accumulation of snow and ice would take
place around both poles than would be possible under any other
conditions. In the second place, there would be little or no check
to this accumulation of ice, because, owing to the quantity of
land around the polar areas, warm oceanic currents could not
reach them, while the warm winds would necessarily bring so
much moisture that they would help on instead of checking the
149
ISLAND I.IF£.
[Hab
process of ice-accnmnlation. If we suppose the continents to be
of the same total area and to Imve tlie same extent and altitudo
of moiintain-ranges ns the present ones, these mountains must
necessarily offer an almost contiwnous barrier to the vapor-hear-
ing -winds from the south, and the result would probably be that
three fourths of tlie laud would bo in the ice-clad condition of
Greenland, while a comparatively narrow belt of the more
Bouthcro lowlands would alone afford habitable surfaces or pro-
duce any woody vegetation,
Notwithstanding, therefore, the criticism above referred to, I
believe that Sir Charles Lyell was substantially right, and that
the two ideal maps given in the " Principles of Geology " (lltli
ed., Vol. I-, p. 270), if somewhat modified so as to allow a freer
passage of currents in the tropics, do really exhibit a condition
of the earth which by geographical changes alone would bring
about a perpetual summer or a» almost nnivei'sal winter. JJnl
we have seen in our sixth chapter that there is the strongest cu-
mulative evidence, almost amounting to demonstration, that for
all known geological periods our continents and oceans have oc-
cupied the same general position they do now, and tliat no such
radical changes in tlie distribution of sea and land as imagined,
by way of hypothesis, by Sir Charles Lyell have ever occurred.
Such an hypothesis, however, is not without its use in our pres-
ent inquiry ; for if we obtain thereby a clear conception of the
influence of such great changes on climate, wo are the better
able to appreciate the tendency of lesser changes, such as have
undoubtedly often occurred.
Land at a linrrirfT to Ocean Curren,t8. — Wo have seen al-
i-ctidy tlie great importance of elevated land to serve us condens-
ers aTid ice-aecumulators; but there is another and hardly less
important effect that may be produced hy an extension of land
in high latitudes, wliJeh is, to act as a barrier to the fiow of ocean
currents. In the region with which wo aro more immediately
interesteil it is easy to sec how a comj>aratively slight alteration
of land and sen, such as has undoubtedly occurred, would pro-
duce an enormous effect on climate. Lot us suppose, for in-
6tHncc, that tho British Isles again became continental, and that
this continental land extended across tlie Faroe Islands and Ice-
CuAP.VIIL] THE CAUSES OF GLACIAL EPOCHS. 143
land to Greenland. The whole of the warm waters of the Atlan-
tic, with the Gulf Stream, would then be shut out from North-
ern Europe, and the result would almost certainly be that snow
would accumulate on the high mountains of Scandinavia till they
became glaciated to as great an extent as Greenland, and the
cold thus produced would react on our own country and cover
the Grampians with perpetual snow, like mountains of the same
hcisrht at even a lower latitude in South America.
If a similar change were to occur on the opposite side of the
Atlantic, very different effects would be produced. Suppose, for
instance, the east side of Greenland were to sink considerably,
while on the west the sea-bottom were to rise in Davis's Strait
so as to unite Greenland with BaflSn's Land, thus stopping alto-
gether the cold arctic current with its enormous stream of ice-
bergs from the west coast of Greenland. Such a change might
cause a great accumulation of ice in the higher polar latitudes,
but it would certainly produce a wonderful ameliorating effect
on the climate of the east coast of North America, and might
raise the temperature of Labrador to that of Scotland. Now
these two changes have almost certainly occurred, either togeth-
er or separately, during the Tertiary period, and they must have
had a considerable effect either in aiding or checking the terres-
trial and astronomical causes affecting climate which were then
in operation.
It would be easy to suggest other probable changes which
would produce a marked effect on climate ; but we will only re-
fer to the subsidence of the Isthmus of Panama, which has cer-
tainly happened more than once in Tertiary times. If this sub-
sidence were considerable, it would have allowed much of the
accumulated warm water which initiates the Gulf Stream to
pass into the Pacific; and if this occurred while astronomical
causes were tending to bring about a cold period in the North-
ern liemisphere, the resulting glaciation might be exceptionally
severe. The effect of this change would, however, be neutralized
if at the same epoch the Lesser and Greater Antilles formed a
connected land.
Now, as such possible and even probable geographical changes
are very numerous, they must have produced important effects ;
lU
ISLAND LIFE.
[PawtL
and tliougli wc nmy ndmit tliat tlm astronomical causes already
explained were the most important in determining tlie last gla-
cial epocli, vc must also allow that geographical changes must
often have Jiad an equally important and perhaps even a pre-
ponderating infinence on climate. We mnst also remember that
changes of land and sea are ahnost always accompanied by c!e-
ration or depression of the pre-existing land ; and ivhereaa the
former prodnees its chief effect by diverting tlio conrse of warm
or cold oceanic currents, the latter is of not less impoi'tanco in
adding to or diminishing those areas of condensation and Ice-ac-
cumulation whicli, as we havo eeeu, are the most efficient agents
in producing glaciation.
If, then, Sir Charles Lyeil may have somewhat erred in attach-
ing too exclusive an importance to geograpliical clianges as
bringing abont mutations of climate, his critics have, I think,
attached far too little importance to these clianges. We know
that they liavo always been in progress to a sufficient extent to
produce important climatal eifecCs; and we shall probably be
nctti'cst the truth if wo consider that great extremes of cold have
only occurred when astronomical and geographical causes were
acting in the same direction, and thus produced n cunmlative
result ; while, through the agency of warm oceanic currents, the
latter alone have been the chief cause of mild climates in high
latitudes, as we shall prove in onr next chapter.'
' Tli« influence of gengrnpliicn] changes on climate is nov! held liy tnnnf geologijts
II lio oppose what tiiey consiitcr tlie extrnvagnni hypotlieses of 1>1'. Croli. Tims, Pro-
finwor Dnna impnica tlie glacinl epoch cliiefl)', if not wtiollv, to elcvniion of the Und
uiuseil l>j ihc Iniernl pcesniire due to ■hrinkitiK of (lie eorili'ii crust il>ai lins caused all
uthcr elevations and depre^Bions. He tayn, "Noiv that elcvaiion of tlie land over
(lie higher lntitutle« which hroaglit on the glacial ent is A nntural result of ilio tame
Bgenry, nnd n tiatnral and nlrnoai neceuary cnunierpart of iho coml-ialand tutwid-
eiice wliii:li rnoBi have been then in proKrets. The accumulating, Tutding, sotidifica-
tion, nnd crystnli'iBiiioa orrocbe titlendin); all the rock-mxlung and mounmin-making
through ihc I'alioainic, Memioic, and Conoznic orni had grenlly siilTened the cmsl
in these parta ; nnd hence, in nfteMimcn, the conlinentnl movements reiutiing frant
llie lateml picsiure necessnrily nppenrcd over the more nanhem poviintis ot the eon-
Tinenc, where ilie Bccutnulaiiuns end oilier chnnecs hnd been rolallvely «mnll. Tu
the siihsidcnce whii-li followed the cUvnlion, the weight of ihn ira-cnp mny hnve con-
iribnted in some small dogroe. Itui llio grent ludnncing movcmeuu of the crust of
Iho cunlinemnl nnd oconnic nrus lliun going fonrnrd must hnvp hnd n gtenllr pre-
Chap. VIII.] THE CAUSES OF GLACIAL EPOCHS. 145
On the Theory of Interglacial Periods and their Probable
C/iaracter. — The theory by which the glacial epoch is here ex-
plained is one which apparently necessitates repeated changes
from glacial to warm periods, with all the consequences and
modifications both of climate and physical geography which fol-
low or accompany such changes. It is essentially a theory of al-
ternation ; and it is certainly remarkable in how many cases ge-
ologists have independently deduced some alternations of cli-
mate as probable. Such are the interglacial deposits indicating
a mild climate, both in Europe and America ; an early phase of
very severe glaciation when the "till" was deposited, with later
less extensive glaciation when moraines were left in the valleys;
several successive periods of submergence and elevation, the
later ones becoming less and less in amount, as indicated by the
raised beaches slightly elevated above our present coast -line;
and, lastly, the occurrence in the same deposits of animal remains
indicating both a warm and a cold climate, and especially the
existence of the hippopotamus in Yorkshire soon after the peri-
od of extreme glaciation.
But although the evidence of some alternations of climate
seems indisputable, and no suggestion of any adequate cause for
them other than the alternating phases of precession during high
eccentricity has been made, it by no means follows that these
changes were always very great — that is to say, that the ice
completely disappeared and a warm climate prevailed through-
out the whole year. It is quite evident that during the height
of the glacial epoch there was a combination of causes at work
which led to a largo portion of Northwestern Europe and East-
ern America being buried in ice to a greater extent even than
ponderating effect in the oscillating agency of all time — lateral pressare within the
crust.'* — American Jnurnal of Science and Arttt^ 3d Series, Vol. IX., p. 318.
In the second edition of his '^Manual of Geology," Professor Dana suggests eleva-
tion of aiTtic hinds sufficient to exclude the Gulf Stream as a source of cold during
glacial epochs. This, he thinks, would have made an e{K>ch of cold at any era of the
globe. A deep submergence of Behring Strait, letting in the Pacific warm current
to the polar area, would have produced a mild arctic climate like that of the Miocene
))eriod. When the warm current was shut out from the polar area, it would yet reach
near to it, and bring \\\\\\ it that abundant moisture necessary for glaciation. —
l*p. i>4 1 , 75."), 7.'»C.
10
146
ISLAND UFE.
[PiW I.
Greenland is now, since it certainly extended beyond the land
and filled up all the shallow seas between our islands and St-an-
dinavia. Among these causes we must reckon a diminntion of
the force of tlio Gulf Stream, or its being diverted from the
northwestern coasts of Europe; and what we have to consider
is, whether the alteration fi-om a long cold winter and short hot
summer to a short mild winter and long cool snmnier would
greatly affect the amount of ice if the ocean currents remaineii
(he game. The force of these currents are, it is true, by onr hy-
pothesis, modified by the increase or diminntion of the ice in the
two hemispheres alternately, and they then react npon climate ;
but they cannot be tlms changed till after the ice-accumniation
has been considerably affected by other causes. Tlieir direction
may indeed be greatly cJianged by slight alterations in the out-
line of the land, wliile tliey may be barred out altogether by
otlier alterations of not very great amount ; but such changes as
these have no relation to the ulteration of climates caused by the
changing phases of precession.
Now tiie existence at the present time of an ice-clad Green-
land is an anomaly in the Northern Hemisphere only to be ex-
plained by the fact tliat cold currents from the jiolar area flow
down both sides of it. In Eastern Asia wo have the lofty Sta-
iiovoi Mountains in the same latitude as the southern part of
Greenland, which, though their summits are covered with per-
petual snow, give rise to no ice-slioct, and, apiiarcntly, even to
no important glaciers — a fact undoubtedly connected with the
warm Japan current flowing partially into the Sea of Ochotsk.
So in Northwest America we have the lofty coast range culmi-
nating in Mt, St. Elias, nearly 15,000 feet high, and an extensive
tract of high land to tlio north and northwest, with glaciers
comparable in liize with those of New Zealand, although situated
in latitude 60" instead of in latitude 45°. Hero, too, wo have tlie
main body of the Japan current turning east and south, and
thus producing a mild climate, little inferior to that of Norway,
warmed by the Gulf Stream. We thus have it made clear that
could the two arctic currents be diverted from Greenland, that
country would become free from ice, and might even bo com-
pletely forest-clad and inhabitable; while if tlie Japan current
Chap. VIII. ] THE CAUSES OF GLACIAL EPOCHS, 147
were to be diverted from the coast of Nortli America and a cold
current come out of Behring Strait, the entire northwestern ex-
tremity of America would even now become buried in ice.
Now it is the opinion of the best American geologists that
during the height of the glacial epoch Northeastern America
was considerably elevated.* This elevation would bring the wide
area of the banks of Newfoundland far above water, causing the
American coast to stretch out in an immense curve to a point
more than GOO miles east of Halifax ; and this would certainly
divert nmch of the greatly reduced Gulf Stream straight across
to the coast of Spain. The consequence of such a state of things
would probably be that the southward-flowing arctic currents
would be much reduced in velocity ; and the enormous quantity
of icebergs continually produced by the ice-sheets of all the lands
bordering the North Atlantic would hang about their shores and
the adjacent seas, filling them with a dense ice-pack far surpass-,
ing that of the antarctic regions, and chilling the atmosphere
so as to produce constant clouds and fog with almost perpetual
snow-storms, even at midsummer, such as now prevail in the
worst portions of the Southern Ocean.
But when such was the state of the North Atlantic (and, how-
ever caused, such mvst htivo been its state during the height of
tlie glacial epoch), can we suppose that the mere change from
the distant sun in winter and near sun in summer to the reverse
could bring about any important alteration — the physical and
(jeographical causes of glaciation remaining unchanged f For,
certainly, the less powerful sun of summer, even though lasting
somewhat longer, could not do more than the much more pow-
erful sun did during the phase of summer in perihelion, while
during the less severe winters the sun would have far less power
than when it was equally near and at a very much gi'cater alti-
tude in summer. It seems to me, therefore, quite certain that
whenever extreme glaciation has been brought about by high ec-
centricity combined with favorable geographical and physical
causes (and without this combination it is doubtful whether ex-
treme glaciation would ever occur), then the ice-sheet will not be
» DnnAs '* Manual of Geology," 2d cd., p. r>40.
ISLAND LIFE.
[P*.
removed during the alternate phases of precession so long as
these geographical nnd phy&iciil causes remaiu unaltered. It is
true tint tlic warm ami cold oceanic currents, which aro the
most important agentd in increasing or dimiQishiDg glaciation,
depend for tlieir strength and efficiency upon the coinpamtivo
extents of the northern and southern ice-sheets; but these ice-
slieets cannot, I believe, increase or diminish to any important
extent unless some geographical or physical change first occurs.'
If this argument is valid, then it would follow that, so long as
eccentricity was high, whatever condition of cliiuate was brought
about by it in combination with geographical canses would per-
sist through several phases of }treeession; but this wonld not
neeesearily be the case when the eccentricity itself changed and
became more moderate. It would then depend upon the pro-
portionato effect of climatal and geographical causes in produc-
ing glaciation as to what change would be produced by the
changing pliasos of procession ; and we can best examine thiit
question by considering the probable effect of the change in
precession during the next period of 10,500 years, with the
present moderate degree of eccentricity.
Prohabh J^fct of Winler in Aphelion on the Climate of
Britain.. — ^Let ua tlien suppose the wintera of the Northern
' In reply (o nn olijeciion of a some'vlint limilnr iintara to lliis, Dr- Croll bns m-
ceiill^ tinted (titafai/icai Magazinr, Ociober, 18711) llint lio " lias not ntBiimcd ttinl
the con pnrat lire diiinppcnmura of tlio lea nn llic wnrm hcminphfra iliitiiig ilie pedod
of high cccenlHcitf U due to imy ndcliiioiinl licut tierired Uora tlic sun in vunsequenm
of (ho GTcntcr length of llie summer,'' but thnt "the i-onl nnd cITeciive cniiso of the
diuifJiwnritnce ofihe Iceivoi tlio enormous irnniferrenceotcquotoriiilhcnt to lempor-
nte and polnr legioni b; ntckna oforcun ctirrenl*." But this it iureir iirRiiingin n
circle ; far the ocexn currenti nra miiinl/ due lo the difference nf teinperninrs of ilie
poUir and cqnntoriol «r«ni coTnhinod will) tlic )>eciirtar form and position of ilie conii-
nenis, nnil aunie ono or mni'e of thCH fiiclnrs nii»t be nlici'cd tr/Lr^ the ocsun cur-
renu tawnid* ilie north polo (nn be incrDnret), Tlie only fnctor avnilnblo is the anl-
nrciic ica ; nnd if this were largely increased, the northiTnid-Sawing currciiia might be
to increased as lo cddU some of the nrciic ice, Bnt ihe very same argampnl applies
to both poles. Without some gcogrnphicnl chnngo the nnlnrclic ice could not mn-
terlnlly diminiali during in winter in iicrtlielinn, nor increase to nny importnnt uxlcnt
dnrinfC the n])pa»ite phase. We iherefui'e twm lo huie no ovailnhle agency by which
lo gelrii] of I he ice over ■ giscjnied conntry so lanij at the ffmgivphiail conJitloiit r«-
maineJ «Hf lianyrd nnd llie (trtntririly cimlinual kl'jh.
Chap.VIII.] the causes OF GLACIAL ErOCIIS. 149
Hemisphere to become longer and much colder, the summers be-
ing proportionately shorter and liotter, without any other change
whatever. The long cold winter would certainly bring down
the snow-line considerably, covering large areas of high land
with snow during the winter months, and extending all glaciere
and ice-fields. This would chill the superincumbent atmosphere
to such an extent that the warm sun and winds of spring and
early summer would bring clouds and fog, so that the sun heat
would be cut off and much vapor be condensed as snow. The
greater sun heat of summer would, no doubt, considerably reduce
the snow and ice ; but it is, I think, quite certain that the extra
accumulation would not be all melted, and that therefore the
snow-line would be permanently lowered. This would be a nec-
essary result, because the greater part of the increased cold of
winter would be stored up in snow and ice, while the increased
heat of summer could not be in any way stored up, but would
be largely prevented from producing any effect, by reflection
from the surface of the snow, and by the intervention of clouds
and fog which would carry much of the heat they received to
other regions. It follows that 10,000 years hence, when our win-
ter occurs in aphelion (instead of, as now, in perihelion), there
will be produced a colder climate, independently of any change
of land and sea, of heights of mountains, or the force of currents.
But if this is true, then the reverse change, bringing the sun
back into exactly the same position with regard to us as it is in
now (all geographical and physical conditions remaining un-
changed), would certainly bring back again our present milder
climate. The change either way would not probably bo very
great, but it might be sufficient to bring the snow-line down to
3000 feet in Scotland, so that all the higher mountains had their
tops covered with perpetual snow. This perpetual snow, down
to a fixed line, would be kept up by the necessary supply of
snow falling during autumn, winter, and spring, and this would,
as we have seen, depend mainly on the increased length and
greatly increased cold of the winter. As both the duration and
the cold of winter decreased, the amount of snow would certain-
ly decrease; and of this lesser quantity of snow a larger propor-
tion would be melted by the longer, though somewhat cooler,
150
ISLAND LIFE.
CtART I.
summer. Tins would follow because tlie total amount of 8im
lieat received during the eummer would be the eaiiie as before,
while it would act'on » less quantity of snow ; there would thus
be a smaller surface to reflect tiie heat, and a mnallcr condensing
area to produce fogs, while the diiniiiiehed intensity of the Eun
would produce a less dense canopy of clouds, which have been
shown to be of prime iinpoi'tancc in cheeking the melting of
snow by the sun. We liave considered this case, for simplicity
of reasoning, on the supposition that all geographical and phys-
ical causes remained imehanged. But if an alteration of the
climate of the whole north temperate and arctic zones occurred,
as here indicated, this would certainly affect both the winds and
enrrents, in the manner already explained (see p. 135), so as to
react upon climate and increase the differences produced by
phases of precession. How far that effect wonid be again in-
creased by corresponding but opposite changes in the Southern
Hemisphere it is impossible to say. It may be that existing ge-
ographical and physical conditions are there such potent agents
in producing a state of glaciation that no change in the phases
of precession would materially affect it. Still, aa the climate of
tlie whole Soutliem Hemisphere is dominated by the great mass
of ice within the Antarctic Circle, it seems probable that if the
winter were shorter and the summer longer the quantity of ice
would slightly diminish; and this would again react on the
northern climate as alitady fully explained.
The Eis»ential I'rinnple of Vlhimtal Change Restated. — The
preceding discussion has been somewhat lengthy, owing to tlie
varied nature of the facts and arguments adduced and the ex-
treme complexity of the subject. But if, as I venture to hope,
the principle here laid down is a sound one, it will be of the
greatest assistance in clearing away some of the many difficulties
that beset the whole question of geological climates. This prin-
ciple is, briefly, that the great features of climate are determined
by a combination of causes, of which geographical conditions
and the degree of eccentricity of the earth's orbit are by far tlie
most important; that when these combine to pTOdnee a eevcie
glacial epoch, the changing phases of precession every 10,500
years have very little, if any, effect on the character of the cH-
Chap. VIII.] THE CAUSES OF GLACIAL EPOCHS. 151
mate, as mild or glacial, though it may modify the seasons ; but
when the eccentricity becomes moderate and the resulting cli-
mate less severe, then the changing phases of precession bring
about a considerable alteration, and even a pai*tial reversal, of
the climate.
The reason of this may perhaps be made clearer by consider-
ing the stability of either very cold or very mild conditions, and
the comparative instability of an intermediate state of climate.
When a country is largely cove'red with ice, we may look upon
it as possessing the accumulated or stored-np cold of a long se-
ries of preceding winters; and, however much heat is poured
upon it, its temperature cannot be raised above the freezing,
point till that store of cold is got rid of — that is, till the ice is
all melted. But the ice itself, when extensive, tends to its own
preservation, even under the influence of heat ; for the chilled
atmosphere becomes filled with fog, and this keeps oflf the sun
heat ; and then snow falls even during summer, and the stored-up
cold does not diminish during the year. When, however, only
a small portion of the surface is covered with ice, the exposed
earth becomes heated by the hot sun, this warms the air, and the
warm air melts the adjacent ice. It follows that, towards the
equatorial limits of a glaciated country, alternations of climate
may occur during a period of high eccentricity ; while nearer the
pole, where the whole country is completely ice-clad, no amelio-
ration may take place. Exactly the same thing will occur in-
versely with mild arctic climates ; but this is a subject which will
be discussed in the next chapter.
This view of the character of the last glacial epoch strictly
corresponds with the facts adduced by geologists. The inter-
glacial deposits never exhibit any indication of a climate whose
warmth corresponded to the severity of the preceding cold, but
rather of a partial amelioration of that cold ; while it is only the
very latest of them, which we may suppose to have occurred
when the eccentricity was considerably diminished, that exhibit
any indications of a climate at all warmer than that which now
prevails.*
' In fi recent number of the Geological Magazine (April, 1880) Mr. SenrleA V.
Probable Date of the Glacial Epoch. — Tlie state of extreme
glaciatioii in the Northern Hemisphere, of which we gave a gen-
eral description at the commencement of the preceding chapter,
is a fact of which there can be no donbt whatever, and it oc-
curred at a period so recent, geologically, that all the mollnsca
were the same as speciea still living. There is clear geological
proof, however, that considerable changes of sea and land, and a
large amount of valley -denudation, took place during and since
the glacial epoch ; wiiile, on the other hand, the surf ace-markings
produced by the ice have been extensively preserved ; and, tak-
ing all these facts into consideration, the i)eriod of about 200,000
years since it reached its maximum, and about 80,000 years
since it passed away, is generally considered by geologists to be
Wood nililitco wlinc lia cuiiBidei's to bo the "candusive olijeclion" to Dr. Croll's eo-
centrkily Elieor]-, ivliitli in, lliat iluiiiig tlie Inst gliicini epocli Eurn|>e aiiij Nnrlli
j\mctii:a ncre glnciuteil ver; taucli in proportion to tlieir respective climntcs now,
ivliich are genemlly nilmiited to be due to i)ie distribution of ocennic cnrrcnis. But
Dr. CroU adinili liit theory "to be liaseluss unleu Iliere iraa n complete diversion of
ths u'omi ocoun currents from the liemispfaera glnciaied,"in whldi cnse there onght
10 be nodiHerence in the extant ofglncinlion in Enropennd No it h America. Wlieth-
eror not tliisisncorrcct ilntement ofDr. Crull's llicory, the abave olijoeiiun cevCninly
Joes not apply to ilie views licre n<ttocnted; but ns I also hold (bo "cecentridiy
Tlieory " in a roodiHed form, it mty be as well to show nliy It does nqi apply. Iti
the first iilnce, I do not believe that tlie Gulf Sd'eAta wns "completely direnod " dur-
ing the glacial epoch, but that it was diminished in furce, and(Bidcsciibcdon p. ISC)
partli/ diverted souliin'nrd. A portion of ill intluenco would, however, aiill retnnin
lu cnuse k diflerence between the climnlca of tlie two sides of llie Allniitic ; and to
ihi> musi be added two other cansei— -the fiir grenter penelrutiun of warm sea-water
into the Enropenn than into itie North American continent, and llie proximity to
America of ilio enorrooiia ice- producing mius of Greenland. Vie linve thus three
distinct cnuiies, nil combining to produce a mure severe winter climate nn ilie west
than on the enal of the Atlantic duiins the glndalepiwh ; and though the firil of these
— ibe Quif Stream—vms not ninrly so powerful ns it b now, neither is the dllTerence
•ndicnied by the ice-extension in the two conntriei so gi-enl ai the present ditterence
of winter lempemiurc. which is the eswntini point to bo considered. The icc-shect
of the United Sinies is usunlly supposed to have extended about ten. or, ni most,
iwoli-e, degrees farther south ihnn it did in Weilcm Europe, wiiereas we must go
lu-enty degrees farther south in the former country to ubtnin the same mean winter
lompemturo ue find In the Inltcr. as miiy be teen by examining any map of winter
inflliiennnls. Tliis diderenco very f.iirly conespundi to the difierence of conditions
existing during the ghwini epoch and the present lime, so fat a% wc ni-o able to eiii-
mnio them, and it certainty ttffurdi no grounds ofohjeciion to the theory by which
ilic glncintion u hero exphiinod.
Chap. VIII.] THE CAUSES OF GLACIAL EPOCHS. 153
ample. There seems, therefore, to be little doubt that in in-
creased eccentricity we have found one of the chief exciting
causes of the glacial epoch, and that we are therefore able to fix
its date with a considerable probability of being correct. The
enormous duration of the glacial epoch itself (including its in-
terglacial mild or warm phases) as compared with the lapse of
time since it finally passed away is a consideration of the great-
est importance, and has not yet been taken fully into account
in the interpretation given by geologists of the physical and
biological changes that were coincident with and probably de-
pendent on it.
Changes of the Sea-level Dependent on Glaciation, — It has
been pointed out by Dr. CroU that many of the changes of
level of sea and land which occurred about the time of the
glacial epoch may be due to an alteration of the sea-level caused
by a shifting of the earth's centre of gravity ; and physicists
have generally admitted that the cause is a real one, and must
have produced some effect of the kind indicated. It is evident
that if ice-sheets several miles in thickness were removed from
one polar area and placed on the other, the centre of gravity of
the earth would shift towards the heavier pole, and the sea
would necessarily follow it, and would rise accordingly. Ex-
treme glacialists have maintained that during the height of the
glacial epoch an ice-cap extended from about 50° N. lat. in
Europe, and 40° N. lat. in America, continually increasing in
thickness till it reached at least six miles thick at the pole ; but
this view is now generally given up. A similar ice-cap is, how-
ever, believed to exist on the antarctic pole at the present day,
and its transferrence to the Northern Hemisphere would, it is
calculated, produce a rise of the ocean to the extent of 800 or
1000 feet. We have, however, shown that the production of
any such ice-cap is improbable, if not impossible, because snow
and ice can only accumulate where precipitation is greater than
melting and evaporation, and this is never the case except in
areas exposed to the full influence of the vapor-bearing winds.
The outer rim of the ice-sheet would inevitably exhaust the air
of so much of its moisture that what reached the inner parts
would produce far less snow than would be melted by the long
ISLASD LIFE.
[P*»
hot days of Binnnicr. Tlic accnniulntions of ice were therefore
probahly confined, in tlio Nortlicni Hemisphere, to tlie coasts
exposed to moist wiiide, and where elevated land and mowntnin-
rnnges afforded condenaera to initiate the process of gluciation ;
and we have already seen that the evidence strongly supports
this view. Eveu with this limitation, however, the mass of ac-
cumulated ice woiitd be enorinoiis, as indeed we have positive
evidence tiiat it was, and might have caused a snfBcient shifting
of the centre of gravity of the earth to produce a submergence
of about 150 or 200 feet.
But this would only be the case if the accumnlation of ice on
one pole was accompanied by a diminution on the other, and
tJiis may have occurred to a limited extent during the earlier
stages of the glacial cpocli, when alternations of warmer and
colder periods would bo caused by winter occurring in perihelion
or aphelion. If, however, as we maintain, no such alternations
occurred when the eccentricity was near its maximum, then the
ice would accumulate in the Southern Ilomisphere at the same
time as in the Northern, unless changed geographical conditions,
of which wo have no evidence whatever, prevented such accu-
mulations. That there was such a greater accunmlation of ice is
shown by the traces of ancient glaciers in the Southern Andes
and in New Zealand, and also, according to several writers, in
South Africa: and the indications in all these localities point to
a period so recent that it must almost certainly have been con-
temporaneous with the glacial period of the Northern Hemi-
sphere.' This greater accumulation of ice in both hemispheres
■ The reranE exienrive Blnciniion of New Zcnlnnd it generally imputeil hy the local
g«ologiaiB ta n grenler elevniiun of the land ; bul I connoi lielgi belisvmg that ilia
high pbaio of eccenirieiiy which caiiied our own glncial epoch wna, nt nil evenu, au
Msigting cnase. Tliis ia rendei'cd more prohRhle if Inken in connectbn with Iho
tulloiving very ileliniie Ratement of gUi-inl ranrkingi In Soalh Africa. Capinin
Arlvard, in tiii "Trnnivuil of To-day" (|). tTI), ajt, "It will be inierratlBK to
(tfologiits nnd oihera lo learn that ilia entire country, from lite miinmiiB of ihe
Qunlhlnnitm lo [lie junction of lite VnnI nnd Omngc riven, diowa mnrk* of having
hnn sne[it over, nnd that at no very diilnnt period, by rnsl mustcs of ice fi^m eatt
to tvsHl, The virintinns ore plainly vialble, acarring the older rovka, nnd marking
llie hill-siilcs — getting lower nnd lower nnd Ims viiiUls n*. desecndlng from (lie
munntiiiiis, the kii]'ji(Mi (smull hlU9]g[nnd uider npavl ; linr, wlieieit-rthe hUlt nniruir
Chap. VIII.] THE CAUSES OF GLACIAL EPOCHS. 155
would lower the whole ocean by the quantity of water abstracted
from it, while any want of perfect synchronism between the
decrease of the ice at the two poles would cause a movement of
the centre of gravity of the earth, and a slight rise of the sea-
level at one pole and depression at the otiier. It is also gener-
ally believed that a great accumulation of ice might cause sub-
sidence by its pressure on the flexible crust of the earth, and we
thus have a very complex series of agents leading to elevations
and subsidences of limited amount, such as seem always to have
accompanied glaciation. This complexity of the causes at work
towards each other, again showing how the vast ice-fields were cliecked, throuTi up,
and raised nguinst their eastern extremities."
This passage is evidently written by a person familiar with the phenomena of
glaciation ; and as Captain A ylward's preface is dated from Edinburgh, lie lias prob-
ably seen similar markings in Scotland. The country described consists of the most
extensive and lofty plateau in South Afiica, rising to a mpuntain-knot with peaks
more than 10,000 feet high, thus offering an appropriate area for the condensation
of vapor and the accumulation of snow. At present, however, the mountains do not
reach the snow-line, and there is no proof that they have been much higher in recent
times, since the coast of Natal is now said to be rising. It is evident that no slight
elevation would now lead to the accumulation of snow and ice in these motmtains,
situated as they are between 27° and 30° S. lat. ; since the Andes, which in 32°
S. lat. reach 23,300 feet high, and in 28° S. lat. 20,000, with far more extensive
plateaus, produce no ice-fields. We cannot, therefore, believe that a few thourand
feet of additional elevation, even if it occurred so recently as indicated by the pres-
ence of striations, would have produced the remarkable amount of glaciation above
described ; while from the analogy of the Northern Hemisphere we may well believe
that it was mainly due to the same high eccentricity that led to the glaciation of
Western and Central Europe and Eastern North America.
These observations confirm those of Mr. G. W. Stow, who, in a paper published
in the (^arterly Journal of the Geological Society (Vol. XXVII., p. 539), describes
similar phenomena in the same mountains, and also mounds and ridges of unstratified
clay packed with angular boulders; while farther south the Stormberg Mountains
are said to be similarly glaciated, with immense accumulations of morainic matter in
all the valleys. We have here all the chief surface phenomena characteristic of a
glaciated country only a few degrees south of the tropic; and, taken in connection
with the evidence of Professor Hartt, who describes true moraines near Rio Ja-
neiro, situated on the tropic itself, we can hardly donbt the occurrence of some
general and wide-spread cause of glaciation in the Southern Hemisphere at a period
so recent that the superficial phenomena are as well preserved as in Europe. Such
evidences of recent glaciation in the Southern Hemisphere are quite inexplicable
without calling in the aid of the recent phase of high eccentricity ; and they may be
fairly claimed as adding another link to the long chain of argument in favor of the
theorv here advocated.
1S6
ISLAND XJFB.
[Paw I.
may explain the somewhat contradictory evidence as to rise and
fall of land, some authors muintaining that it stood higher, and
others lower, during the glacial period.
The Slate of the Planet Mars, ew Bearing on Vie Theory of
Jiccentrk-Uy, «# a Valise of Glacial I'erioda. — It is well known
that tbo polar regions of the planet Mars are covered with white
patches or disks, which undurgo considerable alterations of size
according as they are more or less exposed to the sun's rays.
They have tlierefoi'e been generally considered to be snow or
ice caps, and to prove that Mars is now nndei;going something
like a glacial period. It uiust always be remembered, however,
tliat we are very ignorant of the exact physical conditions of
the snrface of ifars. It appears to have a cloudy atmosphere
like our own, but the gaseous composition of that atmosphere
may be different, and the clouds may be formed of other matter
besides aqueous vapor. Its much smaller mass and attractive
power must have an effect on tiie nature and extent of these
clouds, and the boat of the sun may coUBetinently be modified
in a way quite different from an)'thing that obtains upon our
earth. I^earing these diliiculties and uncertainties in mind, let
us see what arc the actual facts connected witli the supposed
polar snows of Mars.'
Mare offers an excellent subject for comparison with the eartli
as regards this question, because its eccentricity is now a little
greater than the maximum eccentricity of the earth during the
last million years (Mars eccentricity, 0.0931 ; earth eccentricity,
850,000 TCiii-s back, 0,0707) ; the inclination of its axis is also a
little greater than ours (Mare, 28° 51' ; earth, 23° 27"), and botli
Mars and the earth are so situated that ihcy now have the win-
ter of their Jforthern hemispberee in perihelion, that of their
Southern hemispheres being in aphelion. If, therefore, the phys-
ical condition of Mars were the same, or nearly the same, as that
of the earth, all circumstances combine, aecoi-ding to Mr, Croll's
'Tlie astronomical fiicls connecied wiih ilie morJoTia ntid ii|iponmnrc of llie plnnel
are laken from « pnper ly Mr. lidwnrd Cnrp»ntor, M.A., in the Grologieal Mtiga-
tint nf Mnrcli. 1ST7, ciiiiiled " EviJcnfc AtTuriled by Mur* on the Suljoct of GUcUl
I'eriodi," but I arrire nt (omewhat ilitteKtit concluiioni from tli(w« of the wiiier of
the pnper.
Chap. VIII.] THE CAUSES OF GLACIAL EPOCHS. 157
hypothesis, to produce a severe glacial epoch in its southerriy
with a perpetual spring or summer in its northern^ hemisphere ;
while, on the hypothesis here advocated, we should expect gla-
ciation at both poles. As a matter of fact. Mars has two snow-
caps of nearly equal magnitude at their maximum in winter, but
varying very unequally. The northern cap varies slowly and lit-
tle, the southern varies rapidly and largely.
In the year 1830 the southern snow was observed, during the
midsummer of Mars, to diminish to half its former diameter in
a fortnight (the duration of such phenomena on Mars being
reckoned in Martian months equivalent to one twelfth of a Mar-
tian year). Thus on June 23 it was 11° 30' in diameter, and on
July 9 had diminished to 5® 46', after which it rapidly increased
again. In 1837 the same cap was observed near its maximum in
winter, and was found to be about 35° in diameter.
In the same year the northern snow-cap was observed during
its summer, and was found to vary as follow^ :
Mftj 4, Diameter of spot, 31° 24'
June 4,
28° 0'
" 17,
22° 64'
July 4,
18° 24'
** 12,
15° 20'
** 20,
18° 0'
We thus see that Mars has two permanent snow-caps of nearly
equal size in winter, but diminishing very unequally in summer,
when the southern cap is reduced to nearly one third the size of
the northern ; and this fact is held by Mr. Cai*penter, as it was
by the late Mr. Belt, to be opposed to the view of the hemi-
sphere which has winter in aphelion (as the southern now has
both in the earth and Mars) having been alone glaciated during
periods of high eccentricity.*
* In an article in Nature of January 1, 1880, the Rer. T. W. Webb states that in
1877 the pole of Mars (? the south pole) was, according to Schiaparelli, entirely free
of snow, lie remarks also on the regular contour of the supposed snows of Mars as
offering a great contrast to ours, and also the strongly marked dark border which has
often been observed. On the whole, Mr. Webb seems to be of opinion that there can
be no really close resemblance between the physical condition of the earth and Mars,
and that any arguments founded on such supposed similarity are therefore antrust-
worthv.
ISLAND LIFE.
[l'**T L
Before, liowever, we cnii draw any conclusion from tlic ease
of Mars, we must carefully scrutinize the facts and the condi-
tions tbey imply. In the firet place, there is evidently this rad-
icul difference between the state of Mara now and of the earth
during a giaeial period — that Mni-s hns no great ice-sheets spread-
ing over her temperate zone as the earth undoubtedly had. This
we know from the fact of the rapid disappearance of the white
patches over a belt three degrees wide in a fortnight (equal to a
width of abont 100 njiles of our measure), and in the Northern
Hemisphere of eight degrees wide (about 2S0 miles) between
May 4 and July 13. Even with our much more powerful snn,
which gives as more than twice as much lieat as Mars receives,
no such diminntion of an ice-sheet, or of glaciers of even mod-
erate thickness, could possibly occur; but the phenomenon is,
on the contrary, exactly analogous to what actually takes place
on tho plains of Siberia in summer. These, as I am informed by
Mr. Sechohm, are covered with snow during winter and spring
to a depth of six or eight feet, which diminishes very little even
under tho hot suns of May, till warm winds combine with tlio
sun in June, when in about a fortnight the whole of it disap-
pcni'S, and a little later the whole of Northern Asia is free from
its winter covering. As, liowever, tho snn of Mars is so much
less powerful than ours, we may be sure that the snow (if it is
real snow) is much leas thick — -a mere surface-coaling in fact,
such as occurs iu parts of Russia where the precipitation is less,
and tho snow accordingly dues not exceed two or three feet in
thickness.
We now see the reason why the southern pole of Mars parts
with its white covering so much quicker and to so nmch greater
an extent than the northern, for the south pole during summep
is nearest the sun, and, owing to the great eccentricity of Mars,
would have about ono third more heat than during the sunmior
of the Northern Hemisphere ; and this gi-eater heat would cause
tho winds from the equator to be both warmer and more power-
ful, and able to produce tho same effects cm tho scanty Martian
snows as they produce on our northern plains. TJie reason why
both poles of Mars arc almost equally snow-covered in winter is
not diliicuU to understand. Owing to the greater obliquity of
Chap. VIII.] THE CAUSES OF GLACIAL EPOCHS. 159
the ecliptic, and the much greater length of the year, the polar
regions will be subject to winter darkness fully twice as long as
with us, and tlie fact that one pole is nearer the sun during this
period than the other at a corresponding period will therefore
make no perceptible difference. It is also probable that the two
poles of Mars are approximately alike as regards their geograph-
ical features, and that neither of them is surrounded by very
high land on which ice may accumulate. With us at the pres-
ent time, on the other hand, geographical conditions completely
mask and even reverse the influence of eccentricity, and that of
winter in perihelion in the Northern and summer in perihelion
in the Southern Hemisphere. In the north we have a preponder-
ance of sea within the Arctic Circle, and of lowlands in the tem-
perate zone. In the south exactly opposite conditions prevail,
for there we have a preponderance of land (and much of it high
land) within the Antarctic Circle, and of sea in the temperate
zone. Ice, therefore, accumulates in the south, while a thin coat-
ing of snow, easily melted in summer, is the prevalent feature in
the north ; and these contrasts react upon climate to such an ex-
tent that, in the Southern Ocean, islands in the latitude of Ire-
land have glaciers descending to the level of the sea, and con-
stant snow-storms in the height of summer, although the sun is
then actually nearer the earth than it is during our northern
summer!
It is evident, therefore, that the phenomena presented by the
varying polar snows of Mars are in no way opposed to that
modification of Dr. Croll's theory of the conditions which
brought about the glacial epochs of our Northern Hemisphere
which is here advocated, but are perfectly explicable on the
same general principles, if we keep in mind the distinction be-
tween an ice-sheet — which a summer's sun cannot materially di-
minish, but may even increase by bringing vapor to be con-
densed into snow — and a thin snowy covering which may be
annually melted and annually renewed with great rapidity and
over large areas. Except within the small circles of perpetual
polar snow, there can- at the present time be no ice-sheets in
Mars ; and the reason why this permanent snowy area is more
extensive around the northern than around the southern pole
160 ISLAND LIFE. [Part I.
may be partly dne to higher land at the north, but is perhaps
sufficiently explained by the diminished power of the summer
sun, owing to its greatly increased distance at that season in
the Northern Hemisphere, so that it is riot able to melt so much
of the snow which has accumulated during the long night of
winter.
Chap. IX.] ANCIENT GLACIAL EPOCHS. 161
CHAPTER IX.
ANCIENT GLACIAL EPOCHS, AND MILD CLIMATES IN THE ARC-
TIC REGIONS.
Dr. Croll's Views on Ancient Glncinl Epochs. — Effects of Denudation in Destroying
tlie Evidence of Remote Glacial Epochs. — Rise of Sea-level Connected with
Glacial Ei>ochs a Cause of Further Denudation. — What Evidence of Early Glacial
Epoclis may be Expected. — Evidences of Ice-action daring the Tertiary Period.
— The Weight of the Negative Evidence. — Temperate Climates in the Arctic Re-
gions.— Tlie Miocene Arctic Flora. — Mild Arctic Climates of the Cretaceous
Period. — Stratigniphical Evidence of I^ng-continued Mild Arctic Conditions. —
Tiie Causes of JNIild Arctic Climates. — Geographical Conditions Favoring Mild
Northern C'limates in Tertiary Times. — The Indian Ocean as a Source of Heat in
Teriiiiry Times. — Condition of North America during the Tertiary Period. —
EtFect of High Eccentricity on Waim Polar Climates. — Evidences as to Climate
in the Secondary and Palajozoic Epochs. — Warm Arctic Climates in Early Sec-
ondary and Palaeozoic Times. — Conclusions as to the Climates of Secondary and
Tertiary Periods. — General View of Geological Climates as Dependent on the
Physical Features of the Earth's Surface. — Estimate of the Comparative Effects
of Geographical and Physical Causes in Producing Changes of Climate.
If wo adopt tlie view set forth in the preceding cliapter as
to the character of the glacial epoch and of the accompanying
alternations of climate, it must have been a very important
agent in producing changes in the distribution of animal and
vegetable life. The intervening mild periods, which almost
certainly occurred during its earlier and later phases, were some-
times more equable than even our present insular climate, and
severe frosts were probably then unknown. During the eight
or ten thousand yeare that each such mild period lasted, some
portions of the north temperate zone which liad been buried in
snow or ice would become again clothed with vegetation and
stocked with animal life, both of which, as the cold again came
on, would be driven southward, or perhaps partially extermi-
nated. Forms usually separated would thus be crowded together,
and a struggle for existence would follow which must have led
11
162 ISLAND LIFE. [Part I.
to the modification or the extinction of many species. When
the snrvivors in tlie struggle had reached a state of equilibrium,
a fresh field would be opened to them by the later ameliorations
of climate; the more successful of tlie survivors would spread
and multiply ; and after this had gone on for tliousands of gen-
erations, another change of climate, another southward migra-
tion, another struggle of northern and southern forms, would
take place.
But if the last glacial epoch has coincided with, and has been
to a considerable extent caused by, a high eccentricity of the
earth's orbit, we are naturally led to expect that earlier glacial
epochs would have occurred w henever the eccentricity was un-
usually large. Dr. CroU has published tables showing the vary-
ing amounts of eccentricity for three million years back ; and
from these it appears there have been many periods of high ec-
centricity, which has often been far greater than at the time of
the last glacial epoch.* The accompanying diagram has been
drawn from these tables, and it will be seen that the highest
eccentricity occurred 850,000 years ago, at which time the dif-
ference between the sun's distance at aphelion and perihelion
was thirteen and a half inillions of miles, whereas during the
last glacial period the maximum difference was ten and a half
million miles.
Xow, judging by the amount of organic and physical change
that occurred during and since the glacial epoch, and that which
has occurred since the Miocene period, it is considered probable
that this maximum of eccentricity coincided with some part of
the latter period ; and Dr. Croll maintains that a glacial epoch
must then liave occurred surpassing in severity that of which
we have such convincing proofs, and consisting like it of alter-
nations of cold and warm phases every 10,500 years. The
diagram also shows us another long-continued period of high
eccentricity from 1,750,000 to 1,950,000 years ago, and yet
another almost equal to the maximum 2,500,000 years back.
These may perhaps have occurred during the Eocene and Cre-
* London^ Edinburgh^ and Dublin Philosophical Magazine^ Vol. XXXVI., pp. 144-
]oO(lS68).
CHiP.lX] ANCIENT GLACIAL ETOCHS.
taceous epochs respectively, or nil
may liavo been included n'ithin the
limits of the Tertiary period. As
two of these liigh eccentricities
greatly exceed that which caused
our glacial epoch, while the thud is u
almost equal to it and of longer du- |
ration, tliey seem to afford us the k
ineaiis of testing rival theoiies of S
the causes of glaciation. If, as Dr 3
Croll argues, higii eccentricity is the S
great and dominating agency in s
bringing on glacial epociis, geo- n
graphical changes being suboidi- z
nate, then there innst ha\e been g
glacial epochs of great seventy at §
all these three periods ; while if lie |
is also correct in supposing that the «
alternate phases of precession would »
inevitably produce glaciation in one s
hemisphere and a proportionately o
mild and equable climate in the s
opposite hemisphere, tlien we sliould °
havo to look for evidence of ex- ■=
ceptioiialty warm and exceptionally ^
cold periods occurring alternately, S
and with several repetitions, with- g
in a space of time which, geo- "
logically speaking, is very sliort in- 5
deed. |
Let us, then, inqniie first into the ■*
character of the evidence we shonld f^
expect to find of such changes of s*
climate, if they have occurred; we
shall tlien be in a better position to
estimate at its proper value the evi-
dence that actually exists, and, after
giving it due weiglit, to arrive at
^^
u Si
ISLAND LIFE.
[Paw I,
some coneliision na to the theory that best exjilains and har-
monizes it.
Effects of Dentulaiion in Destroying th£ Emdc-nce of Remote
Olaeial £poch». — It may be enpposed tliat if earlier glacial
epochs than the last did really occur, wc ought to meet with
some evidence of the fact corresponding to that -which has
satisfied us of tlie extensive recent glaciation of the Nortliern
Hemisphere; but Dr. Croll and other writers have ably argned
that no 6uch evidence is likely to be found. It is now generally
admitted that subaerial denudation is a much more powerful
agent in lowering and modifying the surface of a country than
was formerly Bopposcd. It lias, in fact, been proved to he so
powerful that tho difficulty now felt ia, not to account for the
denudation whic-h can be proved to have occurred, but to ex-
plain the apparent persistence of superficial features which
ought long ago to have been destroyed.
A proof of the lowering and eating-away of the land surface
which every one can nndei'stand ia to be fouud in the quantity
(if solid matter carried down to the eca and to low grounds by
rivers. This is capable of pretty accflrnte measurement, and has
been so measured for Beveral rivers, large and sniali, in different
parts of the world. The details of these measurements will he
given in a future chapter, and it is only necessary here to state
that the average of them all gives ns this result — that one foot
must be taken off the entire surface of the land each 3000 years,
in order to produce tlie amount of sediment and matter in solu-
tion which is actually carried into the sea. To give an idea of
the limits of variation in different rivers, it may bo mentioned
that the Mississippi is one which denudes its valley at a slow-
rate, taking COOO years to remove one foot; while tho Po is the
most rapid, taking only 7'2i) years to do the same work in iu
valley. Tho cause of this difference is very easy to understand.
A large part of the area of tho Mississippi basin consists of tlio
almost rainless prairie and desert regions of the west, while its
sources are in comparatively arid mountains with scanty snow-
fields or in a low forest-clad jilatean. The Po, on the other
hand, is wholly in a district of abundant rainfall, while its
sources are spread over a great amphitheutre of snowy Alps
Chap. IX.] ANCIENT GLACIAL EPOCHS. 165
nearly 400 miles in extent, where the denuding forces are at a
maximnm. As Scotland is a mountain region of rather abundant
minfall, the denuding power of its rains and rivers is probably
rather above than under the average ; but, to avoid any possible
exaggeration, we will take it at a foot in 4000 years.
Now, if the end of the glacial epoch be taken to coincide with
the termination of the last period of high eccentricity, which
occurred about 80,000 years ago (and no geologist will consider
this too long for the changes which have since taken place), it
follows that the entire surface of Scotland must have been since
lowered an average amount of twenty feet. But over large areas
of alluvial plains, and wherever the rivers have spread during
floods, the ground will have been raised instead of lowered ; and
on all nearly level ground and gentle slopes there will have been
comparatively little denudation ; so that proportionally much
more must have been taken away from mountain-sides and from
the bottoms of valleys having a considerable downward slope.
One of the very highest authorities on the subject of denuda-
tion, Mr. Archibald Geikie, estimates the area of these more rap-
idly denuded portions as ^ly one tenth of the comparatively
level grounds, and he further estimates that the former will be
denuded about ten times as fast as the latter. It follows that the
valleys will be deepened and widened on the average about five
feet in the 4000 years instead of one foot ; and thus many val-
leys must have been deepened and widened one hundred feet,
and some even more, since the glacial epoch, while the more
level portions of the country will have been lowered, on the av-
erage, only about two feet.
Now, Dr. Croll gives us the following account of the present
aspect of the surface of a large part of the country :
'' Go where one will in the lowlands of Scotland and he shall
hardly find a single acre whose upper surface bears the marks
of being formed by the denuding agents now in operation. He
will observe everywhere mounds and hollows which cannot be
accounted for by the present agencies at work. ... In regard
to the general surface of the country, the present agencies may
be said to be just beginning to carve a new line of features out
of the old glacially formed surface. But so little progress has
ISLAND LIFE.
[Paki I.
yet been made tliat the bames, gravel-inoiinds, knoUs of boulder
cl«j, etc., still retain in moat cases their original form.'"
Tlie facte here seein a little inconsietctit, and wo must suppose
that Dr. Croll Laa sotiiewhat exaggerated the universality and
complete preservation of the glaciated surface. The amount of
average denudation, however, Is not a matter of opinion, but of
measurement; aud its conBequenees can in no way be evaded.
They are, moreover, strictly proportionate to the time elapsed ;
and if so much of the old surface of the country Las certainly
been remodelled or carried into the sea since the last glacial
epoch, it becomes evident that any surface phenomena produced
by still earlier glacial epochs must have long since entirely dis-
appeared.
Jiii^ ofihe lka4evel C<mnecl<tfl with Glacial Epochs a Cause
of Ji'urther Denudatimi. — There is also another powerful agent
that must have assisted in the destruction of any such surface
deposits or markings. During the last glacial epoch itself there
were several oscillationH of the land, one at least of considerable
extent, during wliicli shell-bearing gravels were deposited on the
flanks of the Welsh and Irish mountains, now 1300 feet above
sea-level; and there is reason to believe that other enbsidencee
of the same area, thongh perhaps of less extent, may have oc-
cuired at various times during the Tertiary period. Many writ-
ers, as we have seen, connect this subsidence with the glacial pe-
riod itself, tlic unequal amount of ice at the two poles causing
the centre of gravity of the earth to be displaced, when, of
course, the surface of the ocean will conform to it, aud appear
to rise in the one hemisphei'e and sink in the other. If this is
the case, subsidences of the land are natural concomitants of a
glacial period, and will powerfully aid in removing all evidence
of its occurrence. We have seen reason to believe, however, that
during the height of the glacial epoch the extreme cold persisted
through the successive phases of procession ; and if so, both polar
nrcaa wonld probably be glaciated -.yi once. This would cause the
abstraction of a large quantity of water from the ocean, and «
proportionate elevation of the land, which would react on the
' "Climnls nnj Tiiuo in llieir Geologiciil Hclniionc," p. .111.
CuAP. TX.] ANCIENT GLACIAL EPOCHS. 167
accumulation of snow and ice, and thus add another to tliat won-
derful series of physical agents which act and react on each
other so as to intensify glacial epochs.
But whether or not these causes would produce any impor-
tant fluctuations of the sea-level is of comparatively little impor-
tance to our present inquiry, because the wide extent of marine
Tertiary deposits in the Northern Hemisphere, and their occur-
rence at considerable elevations above the present sea-level, af-
ford the most conclusive proofs that great changes of sea and
land have occurred throughout the entire Tertiary period ; and
these repeated submergences and emergences of the land, com-
bined with subaerial and marine denudation, would undoubtedly
destroy all those superficial evidences of ice-action on which we
mainly depend for proofs of the occurrence of the last glacial
epoch.
What Evidence of Early Glacial Epochs may be Ej^pected. —
Although we may admit the force of the preceding argument as
to the extreme improbability of our finding any clear evidence
of the superficial action of ice during remote glacial epochs,
there is, nevertheless, one kind of evidence that we ought to
find, because it is both wide-spread and practically indestruc-
tible.
One of the most constant of all the phenomena of a glaciated
country is the abundance of icebergs produced by the breaking-
off of the ends of glaciers which terminate in arms of the sea, or
of the terminal face of the ice-sheet which passes beyond the
land into the ocean. In both these cases abundance of rocks
and debris, such as form the terminal moraines of glaciers on
land, are carried out to sea and deposited over the sea-bottom of
the area occupied by icebergs. In the case of an ice-sheet it is
almost certain that much of the ground-moraine, consisting of
mud and embedded stones, similar to that which forms the
"till" when deposited on land, will be carried out to sea with
the ice, and form a deposit of marine " till " near the shore.
It has, indeed, been objected that when an ice-sheet covered an
entire country there would be no moraines, and that rocks or
debris are very rarely seen on icebergs. But during every gla-
cial epoch there will be a southern limit to the glaciated area.
and eveiywLere near tliie limit the mouii tain-tope will rise far
above the ice and deposit on it great maBBea of debris ; and as
the ice-sheet spreads, and again as it passes away, this moraiuc-
forming area will successively occupy the whole country. But
even such an ice-clad conutry as (Greenland is now known to
have proti'nding peaks and rocky masses which give rise to mo-
raines on its surface;' and, as rocks from Cnmberland and Ire-
land woi-e carried by the ice-shoet to the Isle of Man, there must
have been a very long period during which the ice-sheets of
Britain and Ireland terminated in the ocean and sent off abun-
dance of rock-laden bergs into the surrounding fleas ; and the
same thing must have occurred along all the coaats of Northern
Europe .ind Eastern America.
"VVe cannot, therefore, doubt that throughout the greater part
of the duration of a glacial epoch the seas adjacent to tlie glaci-
ated countries would receive continual deposits of large rocks,
rock-fiagmcuts, and gravel similai- to the material of modern
and ancient moraines, and analogous to the drift and the numer-
ous travelled blocks which the ice has undoubtedly scattered
broadcast over every glaciated country; and these rocks and
boulders would be embedded in whatever deposits were then
forming, cither from the matter carried down by rivers or from
the mud ground off the rocks and carried out to sea by the glac-
iers themselves. Moreover, as icebergs float far beyond the lim-
its of the countries which gave them birth, these ice-borne mate-
rials would be largely embedded in deposits forming from the
denudation of conutries which had never been glaciated, or from
which the ice had already disappeared.
But if every period of high eccentricity produced a glacial
epoch of greater or lera extent and severity, then, on account of
the frequent occurrence of a high phase of eccentricity during
the 3,OliO,'H)0 years for which we have the tiibles, these houlder
and I'ock-strewn deposits would be both numerous and exten-
eive. 400,000 years ago the eccentricity was almost exactly the
eame as it is now, and it continually increased from that time up
to the glacial epoch. Now, if wc take double the present eccon-
Chap. IX.] ANCIENT GLACIAL EPOCHS. 169
ti'icity as being sufficient to produce some glaciation in the tem-
perate zone, we find (by drawing out the diagram at p. 163 on
a larger scale) that during 1,150,000 years out of the 2,400,000
years immediately preceding the last glacial epoch, the eccentric-
ity reached or exceeded this amount, consisting of sixteen sepii-
rate epochs, divided from each other by periods varying from
30,000 to 200,000 years. But if the last glacial epoch was at its
maximum 200,000 years ago, a space of 3,000,000 years will cer-
tainly include much, if not all, of the Tertiary period ; and even
if it docs not, we have no reason to suppose that tlic character
of the eccentricity would suddenly change beyond the 3,000,000
years.
It follows, therefore, that if periods of high eccentricity, like
that which appears to have been synchronous with our last gla-
cial epoch, and is generally admitted to have been one of its ef-
ficient causes, always produced glacial epochs (with or without
alternating warm periods), then the whole of the Tertiary de-
posits in the north temperate and arctic zones should exhibit
constantly alternating boulder and rock-bearing beds, or coarse
rock-strewn gravels analogous to our existing glacial drift, and
with some corresponding change of organic remains. Let us,
then, see what evidence can be adduced of the existence of such
deposits, and whether it is adequate to support the theory of re-
peated glacial epochs during the Tertiary period.
Evidences of Ice -action during the Tertiary Period. — The
Tertiary fossils both of Europe and North America indicate
throughout warm or temperate climates, except those of the
more recent Pliocene deposits which merge into the earlier gla-
cial beds. The Miocene deposits of Central and Southern Eu-
rope, for example, contain marine shells of some genera now
only found farther south, while the fossil plants often resem-
ble those of Madeira and the Southern States of North America.
Large reptiles, too, abounded ; and man-like apes lived in the
south of France and in Germany. Yet in Northern Italy, near
Turin, there are beds of sandstone and conglomerate full of
characteristic Miocene shells, but containing in an intercalated
deposit angular blocks of serpentine and greenstone often of
enormous size, one being fourteen feet long, and another twen-
170
ISLAND LIFE.
[P*»L
ty-six fuel. Some of the blocks were observed by Sir Charles
Lycll to be faintly striated and partly polisiied on one side, and
they are scattered tJtrougli the beds for a tliickness of nearly one
hundred and fifty feet. It is interesting tliat the particular bed in
which the bloi-ks occur yields no organic remains, though these
are plentifnl both in llie underlying and overlying beds, as if
tlio cold of the icebergs had driven away the organisms adapted
to live only in a comparatively warm sea. Rock similar in kind
to these erratics occurs about twenty miles distant in the Alps.
The Eocene period is even more characterifetically tropical in
ils flora and fauna, since palms and Cyeaduceie, turtles, snakes,
and crocodiles then inhabited England. Yet on the north side
of the Alps, extending from Switzerland to Vienna, and also
eoDth of the Alps near Genoa, there is a deposit of lincly strati-
fied sandstone several thousand feet in thickness, quite destitute
of organic remains, but containing, in several places in Switzer-
land, enormous blocks eitiier angniar or partly rounded, and
composed of oolitic limestone or of granite. Near the Lake of
Thun some of the granite blocks found in this deposit are of
enormous size, one of them being one hundred and tive feet
long, ninety feet wide, and forty-tive feet thick ! The granite
ie red, and of a peculiar kind which cannot be matched any wliei-o
in the Alps, or indeed elsewhere. Similar erratics have also been
found in beds of the same age in the Carpathians and in the
Apennines, indicating probably an extensive Inland European
sea into which glaciers descended from the surrounding nionn-
tains, di'positing these erratics, and cooling the water so as to de-
etrnytho moUuscaand other organisms which had previously in-
habited it. It is to be observed thai wherever these erratics oc-
cur they are always in the vicinity of great mountain-rnnges;
and although these can be proved to liave been in great pait el-
evated during the Tertiary period, we must also remember that
they must have been since very niucli lowered by denudation,
of the amount of which the enonnously thick Eocene and Mio-
cene bedt* now forming portiims of them are in some degree a
measure as well as a proof. It is not, therefore, at all improba-
ble that during some part of the Tertiary period these moun-
tains may liave been far higher than they are now, and this wo
Chap. IX.] ANCIENT GLACIAL EPOCHS. 171
know might be sufficient for the production of glaciers descend-
ing to the sea-level, even were the climate of the lowlands some-
what warmer than at present.*
The Weight of the Negative Evidence, — But when we proceed
to examine the Tertiary deposits of other parts of Europe, and
especially of our own country, for evidence of this kind, not
only is such evidence completely wanting, but the facts are of
so definite a character as to satisfy most geologists that it can
never have existed ; and the same may be said of temperate
North America and of the arctic regions generally.
In his carefully written paper on " The Climate Controversy,"
Mr. Searles V. Wood, Jr., remarks on this point as follows :
"Now the Eocene formation is complete in England, and is ex-
posed in continuous section along the north coast of the Isle of
Wight from its base to its junction with the Oligocene (or Low-
er Miocene according to some), and along the northern coast of
Kent from its base to the Lower Bagshot Sand. It has been in-
tersected by railway and other cuttings in all directions and at
all horizons, and pierced by wells innumerable ; while from its
strata in England, France, and Belgium the most extensive col-
lections of organic remains have been made of any formation
yet explored, and from nearly all its horizons, for at one place
or another in these three countries nearly every horizon may be
said to have yielded fossils of some kind. These fossils, however,
* Professor J.W. Jiidd snys, " In the case of the Alps, I know of no glacial phenom-
ena which are not capaible of being cxphiined, like those of New Zealand, by a great
extension of the area of the tracts above the snow-line which would collect more ample
sup])lies for the glaciers protruded into surrounding plains. And when we survey the
grand panoramas of ridges, pinnacles, and peaks produced, fur the most part, by sub-
aerial action, we may well be prepared to admit that before the inter\'ening ravines
and valleys wei*e excavated, the glaciers shed from the elevated plateaus must have
been of vastly greater magnitude than at present" ('* Contributions to the Study of
Volcanoes," Geological Magazine^ 1876, p. i>36). Professor Judd applies these re-
marks to the last as well as to previous glacial periods in the Alps ; but surely tiiere
has been no sucii extensive alteration and lowering of the surface of the country since
the erratic blocks were deposited on the Jura and the great moraines formed in North
Italy, as tliis theory would im)»ly. We can hardly suppose wide areas to have been
lowered thousands of feet by denudation, and yet have left other adjacent areas ap-
fiarently untouched : and it is even very doubtful whether such an extension of the
STiow-fields would alone suflSce for the effects which were cenainly produced.
1T2
ISLAND LIFE.
[pAirr I.
ivliethtu' tliey be the remains of a flora such as that of Sliep-
pey, or of a vertebrate fauna oontaining the crocodilo and alli-
gator, sach ns is yielded by beds indicative of terrestrial condi-
tions, or uf a inolluscun assemblage such as is present iii tnarine
or fluvio-iiiariue beds of tbo formation, are of nnmistaliably tropi-
cal or subtropical character throughout; and no trace whatever
Las appeared of the intercalation of ft glacial period, much less
of successive intercalations indicative of more than one period
of 10,500 yeare' glaciation. Nor can it be nrged that the glacial
epochs of the Eocene in England were intervals of di-y land,
and 60 have left no evidence of their existence behind them, be-
cause a large part of the continuous sequence of Eocene deposits
in this counti'y consists of alternations of tluviatile, fluvio-marine,
und purely marino strata ; so that it seems impossible that dnr-
ing the accumulation of the Eocene formation in England a gla-
cial period could have occurred without its evidences being abun-
dantly apparent. The Oligocene of Northern Germany and Bel-
gium, and tlio Miocene of those countries and of France, have
also afforded a rich niolluscan fauna, which, like that of the Eo-
cene, has aa yet presented no indication of the intrusion of any-
thing to interfere with its uniformly subti-opieal ebamcter.'' '
This is sufficiently striking; but when we consider that this
enormous series of deposits, many thousand feet in thickness,
consists wholly of alternations of clays, sands, marls, shales, or
limestones, with a few beds of pebbles or conglomerate, not one
of the whole series containing irregular blocks of foreign mate-
rial, bouldcre, or gravel such as we liave seen to be the essential
characteristic of a glacial epoch; and when we find that this
very same general ehai-acter pervades all tiie extensive Tertiary
dcposiCB of temperate North America — we shall, I think, be forced
to the conclusion that no general glacial epochs couid have oc-
curred during their formation. It must be remembered that
the ''imperfection of the geological record" will not Iielp us
here, because the series of Tertiary deposits is nnusnaliy com-
plete, and we nuist snjtpose some deetnictive agency to have se-
lected all the intercalated glacial beds and to have so completely
Chap. IX.] MILD ARCTIC CLIMATES. 173
made away with them that not a fragment remains, while pre-
serving all, or almost all, the irUerglacial beds; and to have act-
ed thus capriciously, not in one limited area only, but over the
whole Northern Hemisphere, with the local exceptions on the
flanks of great mountain-ranges already referred to.
Temperate Clhnatea in the Arctic liegions. — As we have just
seen, the geological evidence of the persistence of subtropical
or warm climates in the north temperate zone during the greater
part of the Tertiaiy period is almost irresistible ; and we have
now to consider the still more extraordinary series of observa-
tions which demonstrate that this amelioration of climate ex-
tended into the arctic zone, and into countries now almost
wholly buried in snow and ice. These warm arctic climates
have been explained by Dr. CroU as due to periods of high ec-
centricity with winter in perihelion, a theory which implies al-
ternating opochs of glaciation far exceeding what now prevails ;
and it is therefore necessary to examine the evidence pretty
closely in order to see if this view is more tenable in the case
of the north polar regions than we have found it to be in that
of the north temperate zone.
The most recent of these milder climates is perhaps indicated
by the abundant remains of large mammalia — such as the mam-
moth, woolly rhinoceros, bison, and horse — in the icy alluvial
plains of Northern Siberia, and especially in the Liakhov Islands,
in the same latitude as the North Cape of Asia. These remains
occur not in one or two spots only, as if collected by eddies at
the mouth of a river, but along the whole borders of the Arctic
Ocean ; and it is generally admitted that the animals must have
lived upon the adjacent plains, and that a considerably milder
climate than now prevails could alone have enabled them to do
so. At what period this occurred we do not know, but one of
the last intercalated mild periods of the glacial epoch itself
seems to offer all the necessary conditions. Again, Sir Edward
Belcher discovered on the dreary shores of Wellington Channel,
in 75^° N. lat., the trunk and root of a fir-tree which had evi-
dently grown where it was found. It appeared to belong to
the species Abies alba, or white fir, which now reaches 68° N.
lat., and is the most northerly conifer known. Similar trees, one
174
ISLAND LIFE.
CP«
four feet iu eirciiiufereiico and thirty feet long, were found by
Lieutenant Mecimni in Prince Patrick's Island, in lat. 76° 12' N. ;
and other arctic explorers liavc found remains of trees ia higli
latitudes wliicli iniiy all probably be referred to the eamo mild
period as that of tlio iee-preserved arctic mammalia.
Similar indications of a recent milder climate are fonud in
Spitzbergen. Professor KordenskjOld says, "At various places
on Spitzbergen, at the bottom of Lomme Bay, at Cape Thord-
sen. in Biomstrand's strata in Advent Bay, there are found
large and well-developed sheila of a bivalve, Mijtilus edulis,
which is not now found living on the coasts of Spitzbergen,
though on the west coast of Scandinavia it everywhere covers
the rocks near the sca-sliore. These shells occur most plenti-
fully in the bed of a river wliicli runs through Ileindeer Viilley
at Capo Thordsen. They are probably washed out of a thin
bed of sand at a height of abont twenty or thirty feet above the
present sen-level, which is intersected by the river. The geologi-
cal age of this bed cannot be very great, and it has clearly been
formed since the present basin of tho Ice Sound, or at least the
greater part of it, has been hollowed out by glacial action,'"'
Tlie Miocene Arctic Flora. — One of the most startling and im-
portant of the scientific discoveries of the last twenty years liu
been that of the relics of a luxuriant Miocene flora in various
parts of the arctiu regions, It is a discovery that was totally un-
expected, and is even now considered by many men of science to
be completely unintelligible ; hut it ia so thoroughly established,
and it has such ;i direct and important bearing on the subjects we
are diRciissing in tho present volume, that it is necessary to lay a
tolerably complete outline of the facts before onr renders,
The Miocene flora of temperate Europe was very like that of
Eastern Asia, Japan, and the warmer part of Eastern North
America of the present day. It is very richly represented iu
Switzerland by well-preserved fossil remains, and after a close
comparison with tho flora of other countries Professor Hccr
concludes that tlic Swiss Lower Miocene flora indicates a climate
corresponding to that of Louisiana, North Africa, and South
' Geologieal Ma^jasinr, IB7C, "Geology of Spililjergen," ]>. 267,
Chap. IX.] MILD ARCTIC CLIMATES. 175
China, while tlie Upper Miocene climate of the same country
would correspond to that of the south of Spain, Southern
Japan, and Georgia (U. S. of America). Of this latter flora,
found chiefly at Oeninghen, in the northern extremity of Switz-
erland, 465 species are known, of which 166 species are trees
or shrubs, half of them being evergreens. They comprise se-
quoyas like the California giant trees, camphor-trees, cinnamons,
sassafras, bignonias, cassias, gleditschias, tulip-trees, and many
other American genera, together with maples, ashes, planes,
oaks, poplars, and other familiar European trees represented
by a variety of extinct species. If we now go to the west coast
of Greenland, in 70° X. lat, we find abundant remains of a flora
of the same general type as that of Oeninghen, but of a more
northern character. We have a sequoya identical with one of
the species founcl at Oeninghen, a chestnut, salisburia, liquid-
ambar, and sassafras, and even a magnolia. We have also seven
species of oaks, two planes, two vines, three beeches, four pop-
lars, two willows, a walnut, a plum, and several shrubs sup-
posed to be evergreens — altogether 137 species, mostly well and
abundantly preserved !
But even farther north, in Spitzbergen, in 78° and 79° N. lat.,
and one of the most barren and inhospitable regions on the
globe, an almost equally rich fossil flora has been discovered, in-
cluding several of the Greenland species, and othere peculiar, but
mostly of the same genera. There seem to be no evergreens
here except coniferae, one of which is identical with the swamp-
cypress (Taxodlmn distichum) now found living in the Southern
United States! There are also eleven pines, two Libocedrus,
two sequoyas, with oaks, poplars, birches, planes, limes, a hazel,
an ash, and a walnut; also water-lilies, pond-weeds, and an iris
— altogether about a hundred species of flowering plants. Even
in Grinnell I^md, within eight and a quarter degrees of the
pole, a similar flora existed, twenty-flve species of fossil plants
having been collected by the last arctic expedition, of which
eighteen were identical with the species from other arctic local-
ities. This flora comprised poplars, birches, hazels, elms, vibur-
nums, and eight species of conifers, including the swamp-cypress,
and the Norway spruce {Pinus alies) which does not now extend
beyond 69i° X. lat.
ISLAND USE.
[V*mL
Fossil plants closely resembling those just mentioned have
been fonnd at many other arctic localities, eepeeially in Iceland,
on tho Mackenzie Eiver in 65° N. lat., and in Alaska. As an
intermediate station we have, in the neighborhood of Dantzie,
in lat. 55° N., a Gimilar flora, with the swamp-cypress, sequoyas,
oaks, poplars, and some cinnamons, laurels, and figs. A little
farther south, near Breslan, north of the Carpathians, a rich flora
haa been fonnd allied to that of Oeninghen, but wanting in some
of the more tropical forms. Again, in the Isle of Mull, in Scot-
land, in about 56^° N. lat. a plant-bed has been discovered con-
taining a hazel, a plane, and a sequoya, apparently identical with
a Swiss Miocene species.
We thus find one weli-markod type of vegetation spread from
Switzerland and Vienna to North Germany. Scotland, Iceland,
Greenland, Alaska, and Spitzbergen, some few of tlie species
even ranging over tho extremes of latitude between Oeninghen
and Spitzbergen ; but the great majority being diatiuet, and ex-
hibiting decided indications of a decrease of temperature aecoi-d-
ing to latitude, though much less in amount tlian now exists.
Some writers have thought that the great similarity of the fiorns
of Greenland and Oeninghen is a proof that they wore not con-
temporaneous, bnt successive; and that of Greenland has been
Bupposed to be as old as the Eocene. But the arguments yet
adduced do not seem to prove sneh a difference of age, because
there is only that amount of specific and generic diversity be-
tween the two which might be produced by distance and differ-
ence of temporatnrc, under the exceptionally equable climate of
the period. We have even now examples of an equally wide
range of well-marked types; as in temperate South AmerJon,
where many of tiio genera and some of the species range from
the Strait of Magellan to Valparaiso — places differing as mnch
in latitude as Switzerland and West Greenland; and the same
may be said of North Australia and Tasmania, where, at a greater
latitudinal distance apart, closely allied forms of Eucalyptus,
Acacia, Casnarina, Stylidium. Goodonia, and many other genera
would certainly form n prominent feature in any fossil flora now
being preserved.
Milil Arcitc Climaks of the CiriacfoUB I'tTiod. — In the Upper
Chap. TX.] MILD ARCTIC CLIMATES. 177
Cretaceous deposits of Greenland (in a locality not far from those
of the Miocene age last described) another remarkable flora has
been discovered, agreeing generally with that of Europe and
North America of the same geological age. Sixty-five species
of plants have been identified, of which there are fifteen ferns,
two cycads, eleven conifei'se, three monocotyledons, and thirty-
four dicotyledons. One of the ferns is a tree-fern with thick
stems, which has also been found in the Upper Greensand of
England. Among the conifers the giant sequoyas are found,
and among the dicotyledons the genera Populus, Myrica, Ficus,
Sassafras, Andromeda, Diospyros, Myrsine, Panax, as well as mag-
nolias, myrtles, and leguminosae. Several of these groups occur
also in the much richer deposits of the same age in North Amer-
ica and Central Europe; but all of them evidently afford such
fragmentary records of the actual flora of the period that it is
impossible to say that any genus found in one locality was ab-
sent from the other merely because it has not yet been found
there. On the whole, there seems to be less difference between
the floras of arctic and temperate latitudes in Upper Cretaceous
than in Miocene times.
In the same locality in Greenland (70° 33' N. lat. and 52° W.
long.), and also in Spitzbcrgen, a more ancient flora, of Lower
Cretaceous age, has been found; but it differs widely from the
other in the great abundance of cycads and conifers and the
scarcity of exogcns, which latter arc represented by a single
poplar. Of the thirty-eight ferns, fifteen belong to the genus
Gleichenia, now almost entirely tropical. There are four genera
of cycads, and three extinct genera of conifers, besides Glypto-
strobus and Torrcya (now found only in China and California), six
species of true pines, and five of the genus Sequoya, one of which
occurs also in Spitzbcrgen. The European deposits of the same
age closely agree with these in their general character; conifers,
cycads, and ferns forming the mass of the vegetation, while exo-
gens are entirely absent, the above-named Greenland poplar be-
ing the oldest known dicotyledonous plant.*
' The preceding account is mostly derived from Professor Heer*8 great work '* Flora
Fossilis Arctica.'*
12
178
ISLA^'D USK.
£P*btL
If we take tliese facts as really representing the flora of the
period, we shsill be forced to condiide that, measured by the
change effected in its plants, the lapse of time between the Lower
and Upper Cretaceous deposits was fur greater than between the
Upper C'retaceoiia and the Miocene — a conclusion quite opposed
to the indications afforded by the inoihisca and the Iirgher ani-
mals of the two periods. It seeme probable, therefore, that these
Lower Cretaceous plants represent local peculiarities of vegeta-
tion such as now sometimes occur in tropical countries. On
sandy or coralline islands in the Malay Areliipelago there will
often be found a vegetation consisting almost wholly of cycads,
pandani, and palms; while a few miles off, on moderately ele-
vated land, not a single specimen of either of thfsc families may
be seen, but a dense forest of dicotyledonous trees covering the
whole country, A lowland vegetation such as that above de-
scribed uiiirht be destroyed and its remains preserved by a sjight
depression, allowing it to be covered np by the detritus of some
adjacent river; while not only would the subsidence of high
land ho n less frequent occurrence, but when it did oecnr the
steep banks would be undermined by the waves, and the trees
falling down would be floated away, and would either be cast
on some distant shore, or slowly decay on the surface or in tlio
depths of the ocean.
From the remarkable series of facts now briefly summarized,
we learn that whenever plant-remains have been discovered
within the arctic regions, either in Tertiary or Cretaeeons de-
posits, they show that the climate was one capable of support-
ing a rich vegetation of trees, shrubs, and herbaceous plants,
similar in general character to that which prarailed in the tem-
perate zonu at the same periods, but showing the influence of
A less congenial climate. These deposits belong to at least four
distinct geological horizons, and have been found widely scat-
tered within the Arctic Cirelo ; yet nowhere has any proof been
obtained of intercalated cold periods such as would bo indicated
by the remains of a stunted vegetation, or a niolluscan fauna
similar to that which now prevails there.
Stratiffraphieal Evidence of Zofig-continved Mild Arctic Con-
diiioHn. — Let us now turn to the stratigraphical evidence, which,
Chap. IX.] MILD ARCTIC CLIMATES. 179
as we liave already shown, offers a crucial test of the occurrence
or non-occurrence of glaciation during any extensive geological
period ; and here we have the testimony of perhaps the greatest
living authority on arctic geology — Professor Nordenskjold. In
his lecture on the " Former Climate of the Polar Regions " he
says, " The character of the coasts in the arctic regions is es-
pecially favorable to geological investigations. While the val-
ley's are, for the most part, tilled with ice, the sides of the moun-
tains in summer, even in the 80th degree of latitude, and to a
height of 1000 or 1500 feet above the level of the sea, are
almost wholly free from snow. Nor are the rocks covered with
any amount of vegetation worth mentioning, and, moreover, the
sides of the mountains on the shore itself frequently present
perpendicular sections which everywhere expose their bare sur-
faces to the investigator. The knowledge of a mountain's geog-
nostic character, at which one, in the more southerly countries,
can only arrive after long and laborious researches, removal of
soil and the like, is here gained almost at the first glance ; and
as we have never seen in Spitzbergen nor in Greenland, in these
sections, often many miles in length, and including, one may say,
all formations from the Silurian to the Tertiary, any boulders
even as large as a child's head, there is not the smallest proba-
bility that strata of any considerable extent containing boulders
are to be found in the polar tracts previous to the middle of the
Tertiary period. Since, then, both an examination of the geog-
nostic condition and an investigation of the fossil flora and
fauna of the polar lands show no signs of a glacial era having
existed in those parts before the termination of the Miocene
period, we are fully justified in rejecting, on the evidence of
actual observation, the hypotheses founded on purely theoretical
speculations which assume the many-times-repeated alternation
of warm and glacial climates between the present time and the
earliest geological ages." * And again, in his " Sketch of the
Geology of Spitzbergen," after describing the various forma-
tions down to the Miocene, he says, " All the fossils found in
the foregoing strata show that Spitzbergen, during former geo-
1 Geologioal Magazine, 1875, p. 531.
180
ISIAND LIFE.
[Part I.
logical ages, enjoyed a magnificent climate, wiiicli, indeed, was
somewhat colder during tlie Miocene penod, bnt was still favor-
able for an extraordinarily abundant vegetation, miicli more
Inxtiriant than that which now occurs even in tlie southern part
of Scandinavia; and I linve in these strata sought in vain for
any sign that, as some geologists have of late endeavored to
render probable, these favorable eliinatie conditions have been
broken off by intervals of ancient glacial periods. The prolilea
I have had the opporttinity to examine during my various Spitz-
bergen expeditions wonld certainly, if laid down on a line, oc-
cnpy an extent of a thousand EmjUsk miles; and if any former
glacial period Lad existed in this region there ought to have
been some trace to be observed of erratic blocks, or other forma-
tions which dietingnieh glacial action. But this has not been
the case. In the strata, whose length I have reckoned alone, I
have not found a single fragment of a foreign rock so large as
a child's head."'
Now it is quite impossible to ignore or evade the force of
this testimony as to the continuous warm climates of the north
temperate and polar zones throughout Tertiary times. The
evidence extends over a vast area, both in space and time; it ie
derived from the work of the most competent living geologists ;
and it is absolutely consistent in its general tendenej'. We have
in the Lower Cretaceous period an almost tropical climate in
France and England, a somewhat lower temperature in the
United States, and a mild insular climate in the arctic regions.
In each successive period the climate becomes soEuewhat less
tropical ; but down to the Upper Miocene it rciimins warm
temperate in Central Europe, and cold temperate within the
|H>lar area, with not a trace of any intervening periods of arctic
cold. It then gradually cools down and merges through the
Pliocene into the glacial epoch in Europe, while in the arctic
zone there is a break in tlie record between the Miocene and
the recent glacial deposits.'
■ CtiJotiiral Ma-iatint. 18TG. p. SC.G.
* I( is iiitfli'csling to uWrve tlint llie Crclnceoiis flnra or tlio United Stnics (that
of (lie Dakritii Bn)U|<) mcltCBItt n (onieHlinl cooler climntc than llinl of ihe fulloning
Eoi'cni' [leriwl, Mr. Do Rnnce(in llie b«'I"8'''«I rippemlix lo rnpinin SirG. Nnre»9
Chap. IX.] MILD AHCTIC CLIMATES. 181
Accepting this as a substantially correct account of the gen-
eral climatic aspect of the Tertiary period in the Northern Hem-
isphere, let us SCO whether the principles we have already laid
down will enable us to give a satisfactory explanation of its
causes.
The Causes of Mild Arctic Climates, — In his remarkable
series of papers on " Ocean Currents," Dr. James CroU has
proved, with a wealth of argument and illustration whose co-
gency is irresistible, that the very habitability of our globe is
duo to the equalizing climatic effects of the waters of the ocean ;
and that it is to the same cause that we owe, either directly or
indirectly, almost all the chief diversities of climate between
places situated in the same latitude. Owing to the peculiar dis-
tribution of land and sea upon the globe, more than its fair pro-
portion of the warm equatorial waters is directed towards the
western shores of Europe, the result being that the British Isles,
Norwa}', and Spitzbergen have all a milder climate than any
other parts of the globe in corresponding latitudes. A very
small portion of the arctic regions, however, obtains this bene-
fit, and it thus remains, generally speaking, a land of snow and
ice, with too short a summer to nourish more than a very scanty
and fugitive vegetation. The only other opening than that be-
tween Iceland and Britain by which warm water penetrates
within the Arctic Circle is tlirough Behring Strait ; but this
is both shallow and limited in width, and the consequence is
that the larger part of the warm currents of the Pacific turns
back along the shores of the Aleutian Islands and Northwest
America, while a very small quantity entei*s the icy ocean.
But if there were other and wider openings into the Arctic
Ocean, a vast quantity of the heated water which is now turned
** Narrative of u Voyage to the Polar Sea **) remarks as follows : ** In the overlying
American Kocenes occur types of plants occurring in the European Miocenes and
still living, proving the truth of Trufessor I^esquereux^s postulate, that the plant
types appear in America a stage in advance of their advent in Europe. These plants
point to a far higher mean temperature than those of the Dakota group, to a dense
atmosphere of vapor, and a luxuriance of ferns and palms.** This is very important
as adding further proof to the view that the climates of former periods are not due
to any general refrigeration, bnt to causes which were subject to change and alterna-
tion in former ages as now.
183
ISLAND LIFE.
[P*j«T I.
backward would entoi- it, and would produce an amelioration of
tiio (■liiiiate of wliieli we ean hardly form a conception. A great
amelioratiou of climate would also be caused hy the breakiiig-
up or the lowering of such arctic highlands as now favor the
accuuinlntion of ice; while the in terpen etration of the sea into
any part of the great continents in the tropical or temperate zones
would again tend to raise ^he winter temperature, and render
any long continuance of snow in their vicinity almost impossible.
Now geologists have proved, quite independently of any sneh
questions as we are Iiere discussing, that changes of the very
kinds above referred to have occurred during the Tertiary
period ; and that there has been, Ejieaking broadly, a steady
change from a comparatively fragmentary and ingular condition
of the great north temperate land3 in early Tertiary times to
that more compact and continental condition which now pre-
vails. It is, no doubt, diHioult and often impossible to deter-
miue liow long any ]Kirticnlar geograi)hical condition lasted, or
whether the changes in one country were exactly coincident
with those in another; but it will be sufficient for our purpose
briefly to indicate those more important changes of hind and
sea during the Tertiary period which must have produced r
decided effect on the climate of the Northern nemisphere.
Gnoyraphtcal Chamjes Favoring Mild JVorthcrii- Vlimafea in
Tertiary Times. — The distribution of the Eocene and Miocene
formations shows that during a considerable portion of the
Tertiary period an inland sea, more or less occupied by an
archipelago of islands, extended across Central Europe between
the Baltic and the Black and Caspian seas, and thence by nar-
rower channels southeastward to the valley of the Enphrates
and the Persian Gulf, thus opening a cominnnication between
the North Atlantic and the Indian Ocean. From the Caspian
also a wide arm of the sea extended dnring some part of the
Tertiary epoch nortliward to the Arctic Ocean, and there is
nothing to show that this sea may not have been in existence
during the whole Tertiary period. Another channel probably
existed over Egypt' into the eastern basin of the Mediterranean
' Mr. S. R. J. Rkenclilc)- infDrros me ilml lie li.
■1c]iosiu, coDMsling of dnya und anliyiiruii!: f^,\<w
Chap. IX.] MILD ARCTIC CLIMATES. 183
and the Black Sea ; while it is probable that there was a eom-
munication between the Baltic and the White Sea, leaving
Scandinavia as an extensive island. Turning to India, we find
tliat an arm of tlio sea of gi*eat width and depth extended from
the Bay of Bengal to the mouths of the Indus ; while the enor-
mous depression indicated by the presence of marine fossils of
Eocene age at a height of 16,500 feet in Western Thibet renders
it not improbable that a more direcl channel across Afghanistan
may have opened a communication between the West Asiatic
and Polar seas.
It may be said tliat the changes here indicated are not war-
ranted by an actual knowledge of continuous Tertiary deposits
over the situations of tlie alleged marine channels ; but it is no
less certain that the seas in which any particular strata were de-
posited were always more extensive than the fragments of tliose
strata now existing, and often immensely more extensive. The
Eocene deposits of Europe, for example, have certainly under-
gone enormous denudation, both marine and subaerial, and may
have once covered areas where we now find older deposits (as
the chalk once covered the weald), while they certainly exist
concealed under some Miocene, Pliocene, or recent beds. We
find them widely scattered over Europe and Asia, and often
elevated into lofty mountain-ranges; and we should certainly
err far more seriously in confining the Eocene seas to the exact
areas where we now find Eocene rocks than in liberally extend-
ing them so as to connect the several detached portions of the
formation whenever there is no valid argument against our
doing so. Considering, then, that some one or more of the sea-
communications here indicated almost certainly existed during
Eocene and Miocene times, let us endeavor to estimate the prob-
able effect such communications would have upon the climate
of the Northern Hemisphere.
Hie Indian Ocean as a Source of Heat in Tertiary Times, —
If we compare the Indian Ocean with the South Atlantic, we
shall see that the position and outline of the former are both
Kgypt nnd Niibin, nt a height of about GOO feet nbove the sea-level ; but these may
have been of fresh-wnter origin.
very favorable for the aeciiimilation of a large body of warm
water moving northward. Its eoiithern opening between
South Africa and Australia is very wide, and the tendency of
the trade-winds would be to coneentrato the currents towai-da
its nortiiwestern extremity, just where tlie two great channels
above described formed an outlet to the nortliern eeas. As will
be shown in onr nineteenth chapter, there were probably, during
the earlier portion of the Tertiary period at least, several large
islands in the space between Madagascar and South India ; but
these had wide and deep channels between them, and their effect
would probably have been favorable to the conveyance of heat-
ed water northward by concentrating the currents, and thus
producing mnssive bodies of moving water analogous to the
Gulf Stream of the Atlantic' Less heat would thus be lost by
evaporation and radiation in the tropical zone, and an impulse
would be acquired which would carry the warm water into the
north polar area. About the same period Australia was divided
into two islands, separated by a wide channel in a north and
south direction (seo Chapter XXII.), and through tins another
current would almost certainly set northward, and be directed
to the northwest by tlie southern extension of Malayan Asia.
The more insular condition at thi>! period of Australia, India,
and North Africa, with the depression and probable fertility of
the Central Asiatic plateau, would lead to the Indian Ocean
being traversed by regular trade-wintls instead of by variable
monsoons, and thus the constant vis a tergo, which is so efficient
in the Atlantic, wonld keep up a steady and powerful current
towards tlie nortliern parts of liie Indian Ocean, and thence
through the midst of the European archipelago to the northern
ecas.
Now it is quits certain that audi a condition as we have here
sketched out would produce a wonderful effect on the climate
of Central Kurope and Western and Northern Asia. Owing to
the warm currents being concentrated in inland seas, instead of
' Ry rcrurring to 0111 mnp of ilio Indinn Occnn »\\a\\ mg tlio Biibmnrino ^nnks in-
dicnliiig oiicioiil islnnds (Clinp. XIX,), U will be oriilwil llini ilio Eoutlienat tmJ«-
wincli, ihcit cxc!«plionn1lf ponetriil, wonlil c«iis« a roit boJj of wiler la enter tbe
<]cc]i Ai'nblaii Se*.
Chap. IX.] MILD ARCTIC CLIMATES. 185
being dispersed over a wide ocean like tlio North Atlantic,
much more heat would be conveyed into the Arctic Ocean, and
this would altogether prevent the formation of ice on the
northern sliores of Asia, which continent did not then extend
nearly so far north and was probably deeply interpenetrated by
the sea. This open ocean to the north, and the warm currents
along all the northern lands, would so equalize temperature that
even the northern parts of Europe might then have enjoyed a
climate fully equal to that of the warmer parts of New Zealand
at the present day, and might have well supported the luxuriant
vegetation of the Miocene period, even without any help from
similar changes in tlie Western Hemisphere.'
Condition of North America during the Tertiary Period. —
But changes of a somewhat similar character have also taken
place in America and the Pacific. An enormous area west of
the Mississippi, extending over much of the Rocky Mountains,
consists of marine Cretaceous beds 10,000 feet thick, indicating
great and long-continued subsidence, and an insular condition
of Western America with a sea probably extending northward
to the Arctic Ocean. As marine Tertiary deposits are found
conformably overlying these Cretaceous strata. Professor Dana
is of opinion that the great elevation of this part of America
did not begin till early Tertiary times. Other Tertiary beds in
California, Alaska, Kamtschatka, the Mackenzie River, the Parry
Islands, and Greenland indicate partial submergence of all these
lands with the possible influx of warm water from the Pacific ;
* In his recently published " r..ectures on Physicnl Geogrnphy," Professor Hnughton
onlcuhites that more than iialf the solar heat of the torrid zone is carried to the
temperate zones by ocean cnrrents. 'J*he Gulf Stream itself carries one twelfth of
the total amount, but it is probable that a very tmsnll fraction of this quantity of heat
reaches the polar seas, owing to the wide area over which the current spreads in the
North Atlantic. The corresponding stream of the Indian Ocean in Miocene times
would have been fully equal to the Gulf Stream in heating power, while, owing to its
being so much more concentrated, a large proportion of its heat may have reached
the polar area. But the Arctic Ocean occupies less than one tenth of the area of
the tropical seas ; so that whatever proportion of the heat of the tropical zone was
conveyed to it would, by being concentrated into one tenth of the surface, produce
an enormously increased effect. Taking this into consideration, we can hardly doubt
that the opening of a sufficient passage from the Indian Ocean to the arctic seas
would produce the effects above indicated.
ISLAND LIFE.
[P«
and the conBiderable elevation of some of the Miocene beds in
Greenland and Spitzbergen renders it prabable that theae coun-
tries were then niucb lesa elevated, in ivliicli case only their
higher summits would bo covered with porpetnal snow, and no
glacicra would descend to the eea.
In the Pacific there was probably an elevation of land eonn-
terbalancing, to some extent, the great depression of so much of
the noi-tliern continents. Our map in Chapter XV. shows the
islands that would be produced by an elevation of the great
shoals nnder a thousand fathoms deep, and it is seen that these
all trend in a southeast and northwest direction, and would thus
facilitate the production of definite currents inipollcd by the
southeast trades towards the Northwest Pacific, where they wonld
gain access to tlic polar seas through Behring Strait, which was,
perhaps, sometimes both wider and deeper than at present.
Eff'-d of these Changes on the Cliviate of the Arctic Eeffions.
— These varions clianges of sea and land, all tending towards a
transferrenco of heat from the equator to the north teniperato
zone, were not improbably still further angmented by the exist-
ence of a great inland South American sea occupying what are
now the extensive valleys of the Amazon and Orinoco, and form-
ing an additional reservoir of superheated water to add to the
supply poured into the North Atlantic.
It is not, of course, supposed that all the modifications hero in-
dicated coexisted at the same time. We have good reason lo
believe, fi-om the known distribution of animals in tlie Tertiary
period, that land commnnications have at times existed between
Europe or Asia and North America, cither by way of Behring
Strait, or by Iceland, Greenland, aud Jjibrador. But the same
e%'idence shows that these land communications wera the excep-
tion rather than the rule, and that they occurred only at long in-
tervals and for short periods, so as at no time to bring about any-
thing like a complete interchange of the productions of the two
continents.' We may therefore admit that the communication
between the tropical and arctic oceans was occasionally inter-
' For Mn nceouni of ihe reMmbl.incos ntid diffuroncea of Ihe mutninoliB of tlie iwo
cuiitinenta daring )lio Teninry epoch, sic mv " Gengrn|>hicnl Diatribaiion of Ani-
lnnl«,-Vul. r., ri>. HO. l.-ifi.
CHAP.IX.J MILD ARCTIC CLIMATES. 187
rupted in one or other direction ; but if we look at a globe in-
stead of a Mercator's chart of the world, we shall see that the
disproportion between the extent of the polar and tropical seas
is so enormons that a single wide opening, with an adequate im-
pulse to carry in a considerable stream of warm water, would be
amply sufficient for the complete abolition of polar snow and
ice, when aided by the absence of any great areas of high land
wuthin the polar circle, such high land being, as we have seen,
essential to the production of perpetual snow even at the pres-
ent time.
Those who wish to understand the effect of oceanic currents
in conveying heat to the north temperate and polar regions
should study the papers of Dr. Croll already referred to. But
the same thing is equally well shown by the facts of the actual
distribution of heat due to the Gulf Stream. The difference
between tlie mean annual temperatures of the opposite coasts of
Europe and America is well known and has been already quoted ;
but the difference of their mean winter temperature is still more
striking, and it is this which concerns us as more especially af-
fecting the distribution of vegetable and animal life. Our mean
winter temperature in the "West of England is the same as that
of the Southern United States, as well as that of Shanghai in
China, both about twenty degrees of latitude farther south ; and
as we go northward the difference increases, so that the winter
climate of Nova Scotia in lat. 45*^ is found within the Arctic
Circle on the coast of Norway ; and if the latter country did
not consist almost wholly of precipitous snow-clad mountains, it
would be capable of supporting most of the vegetable products
of the American coast in tlie latitude of Bordeaux.*
With these astounding facts before us, due wholly to the
tranferrence of a portion of the warm currents of the Atlantic
to the shores of Europe, even with all the disadvantages of an
icy sea to the northeast and ice-covered Greenland to the north-
' Professor Ilnughton lins mndc an elnbomte cnlculntion of the difference between
existing climates and those of Miocene times, for all the places where a Miocene flora
has been discovered, by means of the actual range of corresponding species and gen-
era of plants. Although this method is open to the objection that the ranges of
plants and aiiimnlii arc not determined by temperature only, yet the results may be
188
west, how can we donbt tlic enonnoiisly greater effect of siicli n
condition of tliiugs as lias been' shown to liave existed during
the Tertiary epoch i Instead of oa^ great stream of warm water
spreading widely over the North Atlantic and thus hisiiig the
greater part of its stiire of heat before it reaches the arctic sens,
we should have several etreams conveying the heat of far more
extensive tropical oceans l>y conipavatively narrow inland chan-
nels, thus being able to transfer a large proportion of their heat
inlo the nortliern and arctic seas. Tlie heat that they gave out
during the passage, instead of being widely dispersed by winds
and much of it lost in the higher atmosphere, would directly
ameliorate the climate of the continents they passed through,
and prevent all accumulation of snow except on the loftiest
mountains. The formation of ice in tlie arctic seas would then
be impossible; and the mild winter climate of the latitude of
North Carolina, which, by the Gulf Stream, is ti-ansferred 20'
nortliward to our islands, might certainly, under the favorable
conditions which prevailed during the Cretaceous, Eocene, and
Miocene periods, have been carried another 30" north to Green-
land and Spitzbergen; and this would bring about exactly the
climate indicated by the fossil arctic vegetation. For it must
be remembered that the arctic summers are, even now, really
hotter than ours; and if the winter's cold were abolished and all
np[>roxininlet}' correct, nnd nre ver; interesling. Tlie rullowing tnble, nliicli eiimma.-
rixBS llieie reaulu.u tuken from liii "Lecturm on I'h^Elual Geogrnphv," p. Stii
1 1„«,..»
Pre«i.l
TemperniLrf.
DilTercDM.
Ifc-.'.SO
on'.oo
70MK)
Te'-.oo
85°.e
VJ'A
Cft^.B F.
62'. fi
4M'.2
i-i'-'.a
Ifi°.2 F.
ns°.o
3G°0
3.-.°. 3
4<°.0
2. Danwic
3. Icdnnd:
4. Mnckeiiiia Blvor
n. Disco (Greentmid)
e. Spiishergon
7. Grinnell I.niid
ft is intBrCBtine lo note ilini Icclniid. wliicli is noir exposed to ili« full influence of
the Gulf SlrentD.vrnaonl)' IS^C F. wnrtner in Miocene Iiine« ; while Mnakenalcltiver,
now totiilly removed fioni its influence, wns 28^ wnrmer. Tlii«, ns well nn (lie greiiler
increate of lempernluro at we go nonhnard and Ihe point nroe becomes more limited,
is qniie in nccoi'dniice nilti tlie view of llie cnuses which broughl about Ihe Miocene
rlimaie which is liei-c ndvociitcd.
Chap. IX.] MILD ARCTIC CLIMATES. 189
ice-accnmulation prevented, the high nortliern lands would be
able to support a far more luxuriant summer vegetation than is
possible in our unequal and cloudy climate.*
Effect of High Eccentricity on the Warm Polar Climates, —
If the explanation of the cause of tlie glacial epoch given in the
last chapter is a correct one, it will, I believe, follow that changes
in the amount of eccentricity will produce no important altera-
tion of the climates of the temperate and arctic zones so long
as favorable geographical conditions, such as have been now
sketched out, render the accumulation of ice impossible. The
effect of a high eccentricity in producing a glacial epoch was
shown to be due to the capacity of snow and ice for storing up
cold, and its singular power (when in large masses) of preserving
itself unmelted under a hot sun by itself causing the interposi-
tion of a protective covering of cloud and vapor. But mobile
currents of warm water have no such power of accumulating and
storing up heat or cold from one year to another, though they
do in a pve-eminent degree possess the power of equalizing the
temperature of winter and summer, and of conveying the super-
abundant heat of the tropics to ameliorate the rigor of the arc-
tic winters. However great was the difference between the
amount of heat received from the sun in winter and summer in
the arctic zone during a period of high eccentricity and winter
in aphelion, the inequality would be greatly diminished by the
free ingress of warm currents to the polar area ; and if this was
' Tiic objection has been made that the long polar night would of itself be fiital
to the existence of such a luxuriant vegetation as we know to have existed ns far as
80^ N. lat., nnd that there must have been some alteration of the position of the pole,
or diminution of the obliquity of the ecliptic, to permit such plants as magnolias and
large-leaved maples to flourish. But there appear to be really no valid grounds for
such an objection. Not only are numbers of Alpine and arctic evergreens deeply
buried in the snow for many months without injury, but a variety of tropical and sub-
tropical plants are preserved in the hot-houses of St. Petersburg and other northern
cities which are closely matted during winter, and are thus exposed to as much
darkness as the night of the arctic regions. We have, besides, no proof that any of
the arctic trees or large shrubs were evergreens, and the darkness would ceitninly not
be prejudicial to deciduous plants. Willi a suitable temperature there is nothing to
prevent a luxuriant vegetation up to the pole, and the long-continued day is known
to be highly favorable to the development of foliage, which in the same species is
larger and better developed in Norway than in the South of England.
ISLAND UXE.
[F*nL
sufficient to j)reveiit any accumnlntion of ice, tlie Biimmers would
be warmeil to tlie full extent of the powers of tlie aim dnring
the long polar day, wliich is such «s to give the pole at midsum-
mer more heat diiniig tlie t wen tj-- four hours than the equator
receives during its day of twelve hours. The only difference,
then, that would he directly produced by the clianges of eccen-
tricity and precession would he that the eummera woidd he Rt
one period almost tropical, at the other of a more mild and uni-
form temperate character; while the winters would be at one
time somewhat longer and colder, but never, prolinbly, more
severe than they are now in the West of Scotland.
But though Ligh eccentricity would not directly modify the
mild climates produced hy the state of the Northern Hemisphere
which prevailed during Cretaceous, Eocene, and Miocene times,
it might indirectly affect it hy increasing the mass of antarctic
icG, and thus increasing the force of the trade-winds and the re-
sulting north ward- flowing warm currents. Now there are many
peculiarities in the distribution of plants and of eomo groups of
animals in the Southern Hemisphere which render it almost cer-
tain that there has sometimes been a greater exteusiou of the
nutarctic lands during Tertiary times; and it is therefore not
improbable that a more or less glaciated condition may have been
a long-persistent feature of the Southern Hemisphere, due to the
peculiar distribution of land and eea which favoi-s the production
of ice-fields and glaciers. And as we have seen that during Uio
last three million years the eccentricity has been almost always
much higher than it is now, we should expect that the quantity
of ice in the Southern Hemisphere will usually have been great-
ei', and will thus have tended to increase the force of those oce-
anic currents which produce the mild climates of the Northern
Hemisphere.
Jividencea of Climate In the iSdcandar;/ and Paliporoic £j?och8.
— We have already seen that so far back as the Creiaceous pe-
riod tliero is the most conclusive evidence of the prevalence of a
very mild climate not only in tempemte but also in arctic lands,
while there is no proof whatever, or even any clear indication,
of early glacial epochs at nil comparable in extent and severity
with that which has so recently occurred; and we have seen
Chap. IX.] MILD ARCTIC CLIMATES. 191
reason to connect this state of things with a distribution of land
and sea highly favorable to the transferrence of warm water from
equatorial to polar latitudes. So far as we can judge by the
plant-remains of our own country, the climate appears to have
been almost tropical in the Lower Eocene period ; and as we go
farther back we find no clear indications of a higher, but often
of a lower, temperature, though always warmer or more equable
than our present climate. The abundant corals and reptiles of
the Oolite and Lias indicate equally tropical conditions; but
further back, in the Trias, the flora and fauna become poorer,
and there is nothing incompatible with a climate no warmer
than that of the Upper Miocene. This poverty is still more
marked in the Permian formation, and it is here that clear indi-
cations of ice-action are found in the Lower Permian conglome-
rates of the West of England. These beds contain abundant
fragments of various rocks, often angular and sometimes weigh-
ing half a ton, while others are partially rounded, and have pol-
ished and striated surfaces, just like the stones of the " till."
They lie confusedly bedded in a red unstratified marl, and some
of them can be traced to the Welsh hills from twenty to fifty
miles distant. This remarkable formation was first pointed out
as proving a remote glacial period by Professor Ramsay ; and
Sir Charles Lyell agreed that this is the only possible explana-
tion that, witli our present knowledge, we can give of them.
Permian breccias are also found in Ireland, containing blocks
of Silurian and Old Ked Sandstone rocks, which Professor Hull
believes could only have been carried by floating ice. Similar
breccias occur in the South of Scotland, and these are stated to
be '* overlaid by a deposit of glacial age, so similar to the breccia
below as to be with difliculty distinguished from it."*
These numerous physical indications of ice-action over a con-
siderable area during the same geological period, coinciding with
just such a poverty of organic remains as might be produced by
a very cold climate, are very important, and seem clearly to in-
dicate that at this remote period geographical conditions were
such as to bring about a glacial epoch in our part of the world.
* Geological Magaanne^ 1S73, p. 320.
Ida
ISLAND LIFE.
[F«n-I.
Boulder-beds nlso occur in the Carboniferous formation, both
in Scotland, on tlic continent of Europe, and in Nortli America ;
and Professor Dawson considei*s tbat he has detected true glacial
deposits of ttie same ago in Nova Scotia. Boulder-bods also oc-
cur in ilio Silurian rocks of Scotland and North America, and,
according to Professor Dawson, even in the Hiironian, older than
onr Cambrian. None of tlieee indications are, however, so eatie-
factory as those of Permian age, where we have the very kind
of evidence wo looked for in vain throughout the whole of the
Tertiary and Secondary periods. Its presence in several locali-
ties in eueh ancient rocks as the Permian is not only most im-
portant as indicating a glacial epoch of some kind in Palieozoio
times, but confirms us in the validity of our conchision that the
total' absence of any such evidence thronghout the Tertiary and
Secondary epochs demonstrates the absence of recurnng glacial
epochs in the Northern Hemisphere, notwithstanding the fre-
quent recnrrence of periods of high eccentricity.
Warm Arctic Vlimaifs In Early Secondary and Palimsoic
TVni^A— The evidence we have already adduced of the mild cli-
mates prevailing in the arctic regions thi-oughout the Miocene,
Eocene, and Cretaceous periods is supplemented by a considera-
ble body nf facts relating to still oai'lier epochs.
In the Jurassic period, for example, we have proofs of a mild
arctic climate in the abundant plant-remains of East Siberia
and Amoorland. with less pro<lnctive deposits in Spitzbergen, and
at Andueu in Norway, just within the Arctic Circle. But oven
more remarkable are the marine remains found in many places
in high northern latitudes, among which we may especially men-
tion the numerous ammonites and the vertebne of huge reptiles
of the genera Ichthyosaurus and Tcleosaurua found in the Ju-
rassic deposits of the Parry Islands, in 77° N. iat.
In the still earlier Tn'assic age, nautili and ammonites inhab-
ited the seas of Spitzbergen, where their fossil remains are now
found.
In the Carboniferous formation we again meet with plant-ro-
mains and liede of true coal in the arctic regions. Lcpidodeu-
droris and Onlamites, together with large spreading ferns, are
found at Spitzbergen, and at Bear Island, in the extreme north
Chap. IX.] GEOLOGICAL CLIMATES. 193
of Eastern Siberia ; while marine deposits of the same age con-
tain abundance of large stony corals.
Lastly, the ancient Silurian limestones, which are widely
spread in the high arctic regions, contain abundance of corals
and cephalopodous mollusca resembling those from the same de-
posits in more temperate lands.
Canclimons as to the Climates of Tertiary and Secondary
Periods, — If now we look at the whole series of geological facts
as to the animal and vegetable productions of the arctic regions
in past ages, it is certainly difficult to avoid the conclusion that
they indicate a climate of a uniformly temperate or warm char-
acter. Whether in Miocene, Upper or Lower Cretaceous, Ju-
rassic, Triassic, Carboniferous, or Silurian times, and in all the
numerous localities extending over more than half the polar re-
gions, we find one uniform climatic aspect in the fossils. This
is quite inconsistent with the theory of alternate cold and mild
epochs during phases of high eccentricity, and persistent cold
epochs when the eccentricity was as low as it is now, or lower,
for that would imply that the duration of cold conditions was
greater than that of warm. Why, then, should the fauna and
flora of the cold epochs never be preserved ? Mollusca and many
other forms of life are abundant in the arctic seas, and there is
often a luxuriant dwarf woody vegetation on the land, yet in no
one case has a single example of such a fauna or flora been dis-
covered of a date anterior to the last glacial epoch. And this
argument is very much strengthened when we remember that
an exactly analogous series of facts is found over all the temper-
ate zones. Everywhere we have abundant floras and faunas in-
dicating warmer conditions than such as now prevail, but never
in a single instance one which as clearly indicates colder condi-
tions. The fact that drift with arctic shells was deposited dur-
ing the last glacial epoch, as well as gravels and crag with the
remains of arctic animals and plants, shows us that there is noth-
ing to prevent such deposits being formed in cold as well as in
warm periods; and it is quite impossible to believe that in every
place and at all epochs all records of the former have been de-
stroyed, while in a considerable number of instances those of
the latter have been preserved. When to this uniform testimo-
13
t94
ISLAND LIFE.
tPiiwrl.
ny of the pal iEon to logical evidence we add the equally uniform
abeenee of any indication of those icc-bonic rocks, bonldcre, and
drift whicli are the constant and necessary accompnnimont of
every period of glaciation, and wliich must inevitably pervade
all the marine deposits foruied over a wide area so long as the
state of glaciation continues, we are driven to the conclusion
that the last glacial epoch of the Northern lleinispliei-a was ex-
ceptional, and was not preceded by numerous similar glacial
epochs throughout Tertiary and Secondary time.
But, although glacial epochs (with the one or two exceptions
already referred to) were certainly abscTit, considerable changes
of chmate may have frequently occuri-edjand these would lead
to important changes in the organic world. We can hardly
doubt that some such change occurred between the Lower and
Upper Cretaceous periods, the floras of which exhibit such an
extraordinary contrast iu general character. We have also the
testimony of Mr. J. S. Gardner, who has long worked at the fos-
sil floras of tlie Tertiary deposits, and who states tliat there is
strong negative and some positive evidence of alternating warm-
er and colder conditions, not glacial, contained not only in Eng-
lish Eocene, but all Tertiary beds thi-onghout the world.' In
the case of marine faunas it is more difficult to judge, but the
nnincrous changes in the fossil remains from bed to bed, only a
few feet and sometimes a few inches apart, may be pometimee
due to change of climate; and when it is recognized that such
changes have probably occurred at all geological epochs, and
their effects ai'e systematically searched for, many peculiarities
in the distribution of organisms through the different members
of one deposit may be traced to this cause.
Oeneral View of Oeolor/lcal Climates as Dependent on the
Pkysk-ul Features of i/ie EartJis Surfaae. — In the preceding
chapters I have earnestly endeavored to arrive at an explanation
of geological climates in the temperate and arctic zones which
should be in harmony with the great body of geological facts
now available for their elucidation. If my conclusions as here
set forth diverge considerably from those of Dr. Croll, it is not
' Gtolixjiral Magniiur, 1877, p. 137.
Chap. IX.] GEOLOGICAL CLIMATES. 195
from any want of appreciation of his facts and arguments, since
for many years I have upheld and enforced his views to the best
of my ability. But a careful re-examination of the wliole ques-
tion has now convinced me that an error has been made in esti-
mating the comparative effect of geographical and astronomical
causes on changes of climate, and that, while the latter have un-
doubtedly played an important pait in bringing about the glacial
epoch, it is to the former that the mild climates of the arctic
regions are almost entirely due. If I have now succeeded in
approaching to a true solution of this difficult problem, I owe it
mainly to the study of Dr. CroU's writings, since my theory is
entirely based on the facts and principles so clearly set forth in
his admirable papers on " Ocean Currents in Relation to the Dis-
tribution of Heat over the Globe." Tiie main features of this
theory, as distinct from that of Dr. Croll, I will now endeavor to
summarize.
Looking at the subject broadly, we see that the climatic con-
dition of the Northern Hemisphere is the result of the peculiar
distribution of land and water upon the globe ; and the general
permanence of the position of the continental and oceanic areas
— which we have shown to be proved by so many distinct lines
of evidence — is also implied by the general stability of climate
throughout long geological periods. The land surface of our
earth appears to have always consisted of three great masses in
the north temperate zone, narrowing southward, and terminating
in three comparatively narrow extremities represented by South-
ern America, South Africa, and Australia. Towards the north
these masses have approached each other, and have sometimes
become united, leaving beyond them a considerable area of
open polar sea. Towards the south they have never been much
farther prolonged than at present ; but far beyond their extrem-
ities an extensive mass of land has occupied the south polar
area.
This arrangement is such as would cause the Northern Hem-
isphero to be always (as it is now) warmer than the Southern,
and this would lead to the preponderance of northward winds
and ocean currents, and would bring about the concentration of
the latter in three great streams carrying warmth to the north
ISlMilli IJF£.
xU.
polar regions. Tliese sti-eanis wonld, ns Dr. Croll lifts so well
sliown, be gi'eatly increased in power by the giaciation of the
eouth polar land; tiiid whenever any conaiderablo portion of
this land was elevated, such a condition of giaciation would cer-
tainly be bronglit about, and woidd be heightened whenever a
high degree of eccentricity prevailed.
It appears to he the general opinion of geologists that the
great continents liavc undergone a process of development fi'ora
earlier to later times. Profes-sor Duua says, " The North Amer-
ican continent, which since early time had been graduidly ex-
panding in cacii direction from the Northern Azoic, eastward,
westward, and southward, and which, after the Palteozoic, was
flnished in its rocky foundation, excepting on the borders of the
Atlantic and Pacitic and the area of the Rocky Houn tains, had
reached its full expatision at the close of the Tertiary period.
The progress from the first was uniform and systematic: the
land waa at all times simple in outline; and its enlargement
took place with almost the regularity of an exogenous plant." '
A similar development undoubtedly took place in the Euro-
pean area, which waa apparently never so compact and so little
interpenetrated by the sea as it ia now, while Europe and Asia
liavc only become united into one unbroken mass since late
Tertiary times.
If, however, the greater contincuta have become more com-
pact and massive from age to tige, and have received tlieir chief
extensions northward at a comparatively recent period, while
the antarctic lands had a corresponding but somewhat earlier
development, we have all the conditions requisite to explain the
persistence, with slight fluctuations, of warm climates far into
the north polar area throughout Palajozoic, Mesozoic, and Ter-
tiary times. At length, during the latter part of the Tertiary
epoch, a considerable elevation took place, closing up several of
the water passages to the north, and raising up extensive areas
in the arctic regions to become the receptacle of enow and ice
fiehls. This elevation is indicated by the abundance of Miocene
and the absence of Pliocene deposits in the arctic zoTie, and tlie
' "Mnmifll of Goolofi.''," H J cJ., p. CiS.
mtL
Chap. IX.] GEOLOGICAL CLIMATES. 197
considerable altitude of mauy Miocene rocks in Europe and
Nortli America ; and the occurrence at this time of a long-
continued period of high eccentricity necessarily brought on
the glacial epoch in the manner already described in our last
chapter.
We thus see that the last glacial epoch was the climax of a
great process of continental development which has been going
on throughout long geological ages ; and that it was the direct
consequence of the north temperate and polar land having at-
tained a great extension and a considerable altitude just at the
time when a phase of very high eccentricity was coming on.
Throughout earlier Tertiary and Secondary times an equally
high eccentricity often occurred, but it never produced a glacial
epoch, because the north temperate and polar areas had less high
land, and were more freely open to the influx of warm oceanic
currents. But wherever great plateaus with lofty mountains
occurred in the temperate zone a considerable local glaciation
might be produced, which would be specially intense during
periods of high eccentricity ; and it is to such causes we must
impute the indications of ice-action in the vicinity of the Alps
during tho Tertiary period. The Permian glaciation appears to
have been more extensive, and it is quite possible that at this
remote epoch a sufficient mass of high land existed in our area
and northward towards the pole to have brought on a true
glacial period comparable with that which has so recently passed
away.
Estimate of the Comparative Effects of Geographical and
Astronomical Causes in Producing Changes of Climate. — It
appears, then, that while geographical and physical causes alone,
by their influence on ocean currents, have been the main agents
in producing the mild climates which for such long periods pre-
vailed in the arctic regions, the concurrence of astronomical
causes — high eccentricity with winter in aphelion — was neces-
sary to the production of the great glacial epoch. If we reject
this latter agency, we shall be obliged to imagine a concurrence
of geographical changes at a very recent period of which we
have no evidence. We must suppose, for example, that a large
part of the British Isles — Scotland, Ireland, and Wales at all
. ISI.AND UXR.
tPuxI,
events — were siinnltaneonsly elevated so as to bring extensive
areas above the line of perpetual enow; that about the Eanie
time Scandinavia, the Alps, and tbe Pyrenees received a similar
incroaeo of altitude; and that, almost Bimiiltanoonsly, Eastern
North America, the Sierra Nevada of California, the CaQcaeiie,
Lebanon, the southern mountains of Spain, the Atlas range, and
the Himalayas were each some thousands of feet higher thnn
they are now; for all these mountains present ns with indica-
tions of a recent extension of their glaciers, in snperficial phe-
nomena so similar to those which occur in our own country and
in "Western Enrope that we cannot suppose them to belong to
a different epoch. Snch a supposition is rendered more difficult
by the general concurrence of scientific testimony to a partial
submergence during the glacial epoch, not only in all parts of
Britain, but in North America, Scandinavia, and, as shown by
the wide extension of the drift, in Northern Europe ; and when
to this we add the difficulty of understanding how any probable
addition to the altitude of our islanda could have brought about
the extreme amount of glacJation which they certainly under-
went, and when, further, we know that a phase of very high
eccentricity did occur at a period which is generally admitted
to agree well with physical evidence of the time elapsed since
the eoM passed away, there seems no sufficient reason why such
an agency should be ignored.
No doubt a prejudice has been excited against it in the minds
of many geologists, by its being thought to lead neceamrii'y to
frequently recurring glacial epochs throughout all geological
time. But I have liero endeavored to show that this is not a
nccessai-y consequence of tho theory, because a concurrence of
favorable geographical conditions is essential to the initiatiou
of a glaciation, which, when once initiated, has a tendency to
maintain itself throughout the varying phases of precession
occurring during a period of high eccentricity. Wlion. how-
ever, geographical conditions favor warm arctic climates — as it
has been shown they have done throughout tho larger portion
of geological time — then cliangca of eccentricity, to however
great an extent, have no tendency to bring about a state of
glaciation, because warm oceanic currents have a prepondei'atiug
Chap. IX.] GEOLOGICAL CLIMATES. 199
influence, and without very large areas of high northern land to
act as condensers, no perpetual snow is possible, and hence the
initial process of glaciation does not occur.
The theory as now set forth should commend itself to geolo-
gists, since it shows the direct dependence of climate on pliysical
processes which are guided and modified by those changes in the
earth's surface which geology alone can trace out. It is in per-
fect accord with the most recent teachings of the science as to
the gradual and progressive development of the earth's crust
from the rudimentary formations of the Azoic age, and it lends
support to the view that no important departure from the great
lines of elevation and depression originally marked ont on the
earth's surface have ever taken place.
It also shows us how important an agent in the production of
a habitable globe, with comparatively small extremes of climates
over its whole area, is the great disproportion between the ex-
tent of the land and the water surfaces. For if these propor-
tions had been reversed, large areas of land would necessarily
have been removed from the beneficial influence of aqueous
currents or moisture-laden winds ; and slight geological changes
might easily lead to half the land surface becoming covered with
perpetual snow and ice or being exposed to extremes of summer
heat and winter cold, of which our water-permeated globe at
present affords no example. We thus see that what are usually
regarded as geographical anomalies — the disproportion of land
and water, the gathering of the land mainly into one hemisphere,
and the singular arrangement of the land in three great south-
ward-pointing masses — are really facts of the greatest signifi-
cance and importance, since it is to these very anomalies that
the universal spread of vegetation and the adaptability of so
large a portion of the earth's surface for human habitation are
directly due.
ISLASU LIFE.
Vnrioui Eaiiinnlea ofGralugLcnl Time, — Denuiiation and Deposition of Strain as a
Ueuure of Time. — Hour to KEtimnla Ihe Tliickneu of tlie Sedimcnuiry Itocks, —
How 10 Entimnlc tEie Average Itnte of Deposition of tlie Sedimentary Kocks. —
The liaie of Geological Change probnbl; Greater in very RomotQ Times. — Value of
the Prcccdins Estimate of Geological Time. — Orennic Modification Dependent on
Cliitnge of Conditions. — GeogrBjihicBl Miitntions as a Motive Power in Bringing
about Organic Clmngei. — Climatal Revolutions as an Agent in Producing Organia
Changes. — Present Condition of tlie EaitU one of Exceptional Sinbility as reganli
Climnlo. — Date of Loiit Glncinl Epoch, and its Bearing on the MensaremenE of
Geolugical Time. —Coiicl tiding liemnrks.
The subjects discussed in the last tliree chapters introduce us
to a ditBculty wliicli has hitherto been considered a very for-
midable one^tliat the maxiuiuin age of the habitable cartli, as
deduced from phj-sical considerations, does not afford siiflicient
time either for the geological or the organic changes of which
we have evidence. Geologists continually dwell on the slow-
iiCBs of the processes of npheaval and subsidence, of denudation
of the earth's snrface, aud of the formation of new strata ; while
on the theory of development as expounded by llr. Darwin the
variation and moditicntion of organic forms is also a very slow
process, and has usually been considered to i-etjuii'o an even
longer series of ages than might satisfy the requirements of
physical geology alone.
As an indication of the periods usually contemplated by geol-
ogists, wo may i-efer to Sir Charles Lyell's calculation in the
tenth edition of his "Principles of Geology" (omitted in later
editions), by which he arrived at two hundred and forty millions
of years as having probably elapsed since the Cambrian period
— a very moderate estimate in the opinion of most geologists.
This cnleulation was founded on the rate of modification of the
Chap. X.] THE EARTH'S AGE. 201
species of mollnsca ; but much more recently Professor Haugli-
ton has arrived at nearly similar figures from a consideration of
the rate of formation of rocks and their known maximum thick-
ness, whence he deduces a maximum of two hundred millions of
years for the whole duration of geological time as indicated by
the series of stratified formations.* But in the opinion of all our
first naturalists and geologists, the period occupied in the forma-
tion of the known stratified rocks only represents a portion, and
perhaps a small poi*tion, of geological time. In the last edition
of the " Origin of Species " (p. 286), Mr. Darwin says, " Conse-
quently, if the theory be true, it is indisputable that before the
lowest Cambrian stratum was deposited long periods elapsed — as
long as, or probably far longer than, the whole interval from
the Cambrian ago to the present day ; and that during these
vast periods the world swarmed with living creatures." Pro-
fessor Iluxley, in his anniversary address to the Geological So-
ciety in 1870, adduced a number of special cases showing that,
on the theory of development, almost all the higher forms of
life must have existed during the Palaeozoic period. Thus, from
the fact that almost the whole of the Tertiary period has been
required to convert the ancestral Orohippus into the true horse,
ho believes that, in order to have time for the much greater
change of the ancestral Ungulata into the two great odd-toed
and even-toed divisions (of which change there is no trace even
among the earliest Eocene mammals), wo should require a large
portion, if not the whole, of the Mesozoic or Secondary period.
Another case is funiished by the bats and whales, both of which
strange modifications of the mammalian type occur perfectly de-
veloped in the Eocene formation. What countless ages back must
we then go for the origin of these groups — the whales from some
ancestral carnivorous animal, and the bats from the insectivora!
And even then we have to seek for the common origin of car-
nivora, insectivora, ungulata, and marsupials at a far earlier pe-
riod ; so that, on the lowest estimate, we must place the origin
of the mammalia very far back in Palaeozoic times. Similar
evidence is afforded by reptiles, of which Professor Huxley says,
» Nature, Vol. XVUI. (July, 1878), p. 268.
aoa
ISLAim LIFE.
[T«tJ.
" If the vcTj small differences which are observable between the
crocodiles of the older Secondary formations and those of the
present day furnish any sort of an approximation towards an
estimate of the average rate of change among reptiles, it is al-
most appalling to reflect how far back in Palteozoic times we
ninst go before we can hope to arrive at that common stock from
which the crocodiles, lizards, OrnithoBcelida, and /*lesio8auria,
which had attained so great a development in the Triaseic epoch,
innst have been derived." Pi'ofessor Ilanisay lias ex]>ressed sim-
ilar views, derived from a geiieritl study of the whole series of
geological formations and their contained fossils. He says, speak-
ing of the abnndaiit, varied, and weli-developed fauna of the
Cambrian period, "In this earliest known varied life we find
no evidence of its having lived near the beginning of tlie zoo-
logical scries. In a broad sense, compared with what must have
gone before, both biologically and physically, all the phenomena
connected with this old period seem, to my mind, to be of quite
a recent description ; and the climates of seas and lands were of
the very same kind as those the world enjoys at the present
day." '
These opinions, and the facts on which they are founded, are
so weighty that we can hardly doubt that, if the time since the
Cambrian epoch is correctly estimated at two hundred millions
of years, the d.tte of the commencement of life on tlie earth can-
not bo much less than five hundred millions; while it may not
improbably have been longer, because the reaction of the organ-
ism under changes of the environment is believed to have been
less active in low and simple than in high and comple-ii forms
of life, and thus the processes of organic development may for
countless ages have been excessively slow.
But, according to the physicists, no such periods as are here
contemplated can be granted. From a consideration of the pos-
sible sources of the heat of the sun, as well as from calculations
of the period during which the earth can have been cooling to
bring about the present rate of increase of temperature as we
■ *'<>n ihc Com |iHrii live Vnlae drCcrrnin Geological ^ges Considel'ed m
Geologiciil Time," Procetdingii o/ Iht Rayal Socitiy, 1871, p. 331.
Chap. X.] THE EARTH'S AGE. 203
descend beneath the surface, Sir William Thomson concludes
that the crust of the earth cannot have been solidified much long-
er than one hundred million years (the maximum possible be-
ing four hundred millions), and this conclusion is held by Dr.
CroU and other men of eminence to be almost indisputable.* It
will therefore be well to consider on what data the calculations
of geologists have been founded, and how far the views here set
forth as to frequent changes of climate throughout all geolog-
ical time may affect the rate of biological change.
Denudation and Depodtian of Strata as a Measure of Time.
— The materials of all the stratified rocks of the globe have been
obtained from the dry land. Every point of the surface is ex-
posed to the destructive influences of sun and wind, frost, snow,
and rain, which break up and wear awa}^ the hardest rocks as
well as the softer deposits, and by means of rivens convey the
worn material to the sea. The existence of a considerable depth
of soil over the greater part of the earth's surface ; of vast heaps
of rocky debris at the foot of every inland cliff; of enormous
deposits of gravel, sand, and loam ; as well as the shingle, peb-
bles, sand, or mud of every sea-shore, alike attest the univer-
sality of this destructive agency. It is no less clearly shown by
the way in which almost every drop of running water — whether
in gutter, brooklet, stream, or large river — becomes discolored
after each heavy rainfall, since the matter which causes this dis-
coloration must be derived from the surface of the country, must
always pass from a higher to a lower level, and must ultimately
reach the sea, unless it is first deposited in some lake, or by the
overflowing of a river goes to form an alluvial plain. The uni-
versality of this subaerial denudation, both as regards spac^ and
time, renders it certain that its cumulative effects must be very
great; but no attempt seems to have been made to determine
the magnitude of these effects till Mr. Alfred Tylor, in 1853,*
pointed out that by measuring the quantity of solid matter
brought down by rivers (which can be done with considerable
* Transactions of the Royal Societjf of Edinburgh^ Vol. XXIII., p. 101 ; Quarterly
Journal of Science^ 1877 (Croll, on the ** Probable Origin and Age of the Sun ").
* Philosophical Magazine^ April, 1858.
ao4
ISLAND LIE-E.
[7uCTl.
acetiracy), we may obtnin the amount of lowering of the land
area, and also the viae of tbe ocean-level, owing to the quantity
of matter deposited on its floor. A few jeara later Dr. Croll
applied the eanie method in more detail to an estimate of the
amount by which the land is lowered in a given period ; and
the validity of this method has been upheld by Professor Geikie,
Sir Charles Lyell, and all onr best geologists, as affording a means
of actually determining with some approach to accuracy the
time occupied by one importaut phase of geological change.
The quantity of matter carried away from the land by a river
is greater than at first sight appears, and is more likely to be
under- than over-estimated. By taking samples of water near
tlie month of a river (but above the influence of the tide) at a
sufficient number of points in its channel and at different depths,
and repeating this daily or at other short intervals throughout
the year, it is easy to determine the quantity of solid matter
Iield in auspcusion and solution; and if corresponding observa-
tions determine the quantity of water that is discharged, the
total amount of solid matter brought down annually may be
calculated. But, besides this, a considerable quantity of sand,
or even gravel, is carried along the bottom or bed of tlie river,
and this has rarely been estimated, so thnt the figures hitherto
obtained are usnally under the real quantities. There is also
another source of error caused by the quantity of matter the
river may deposit in lakes or in flooded hinds during its course;
for this adds to the amount of denudation performed by the
river, although the matter so deposited does not come down to
the sea. After a careful examination of all the best records,
Professor A, Geikie arrives at the following results as to the
quantity of matter removed by seven rivers from their basins,
estimated by the number of years required to lower the whole
surface an average of one foot :
The MiBbiHirpi ™mov
eionefootinGOOO
ThoGnngM
H3.-.8
TheUonnsIIo "
nut
The Rhono
1628
The l>n»ubo
0848
The Po
T29
The Mill
472a
Chap. X.] THE EARTH'S AGE. 205
Here we see an intelligible relation between the character of
the river basin and the amount of denudation. The Mississippi
has a large portion of its basin in an arid country, and its sources
are either in forest -clad plateaus or in mountains free from
glaciers and with a scanty rainfall. The Danube flows through
Eastern Europe, where the rainfall is considerably less than in
the West, while comparatively few of its tributaries rise among
the loftiest Alps. The proportionate amounts of denudation be-
ing, then, what we might expect, and as all are probably under
rather than over the truth, we may safely take the average of
them all as representing an amount of denudation which, if not
true for the whole laud surface of the globe, will certainly be so
for a very considerable proportion of it. This average is almost
exactly one foot in three thousand years.' The mean altitude
of the several continents has been estimated to be as follows:
Europe, 671 feet; Asia, 1132 feet; Africa, 900 feet; North
America, 748 feet ; and South America, 1151 feet. At the rate
of denudation above given, it results that, were no other forces
at work, Europe would be planed down to the sea-level in about
two million years ; while, if we take a somewhat slower rate for
North America, that continent might last about three million
years.' This also implies that the mean height of these conti-
' It has usually been the practice to take the amoant of denudation in the Missis-
sippi yalley, or one foot in six thoasnnd years, as a measure of the rate of denuda-
tion in Europe, from an idea apparently of being on the "safe side," and of not over-
estimating the rate of change. But this appears to me a most unphilosopliical mode
of proceeding, and unworthy of scientific inquiry. What should we think of astron-
omers if they always took the lowest estimates of planetary or stellar distances, in-
stead of the mean results of observation, **in order to be on the safe side?'* As if
error in one direction were any worse than error in another. Yet this is what geolo-
gists do systematically. Whenever any calculations are made involving the antiquity
of man, it is those that give the lowest results that are always taken, for no reason
apparently except that there was, for so long a time, n prejudice, both popular and
scientific, against the great antiquity of roan ; and now that a means has been found
of measuring the rate of denudation, they take the slowest rate instead of the mean
rate, apparently only because there is now a scientific prejudice in fiivor of extremely
slow geological change. I take the mean of the whole ; and, as this is almost ex-
actly the same as the mean of the three great European rivers — the lihone, Danube,
and Po — I cannot believe that this will not be nearer the truth for Europe than tak-
ing one North American river as the standard.
' These figures are merely used to give an idea of the rate at which denudation is
206
ISLAND LIFE.
[PamI.
iients would have Leen double wliat it is now two million and
three million years ago respectively ; and, as we have no reason
to suppoBo this to have been the case, we are led to infer the
constant action of that upheaving force whicli tlie presence of
sedimentary fonnations even on the highest monntains also
demonstrates.
Wo have already discussed the unequal rate of denudation on
hills, valleys, and lowlands in connection with the evidence of
remote glacial epochs (p. 104); what we have now to consider
is, what becomes of all this denuded matter, and how far the
known rate of denudation affords ns a nieasnre of the rate of
deposition, and thus gives us some indication of tlie lapse of
geological time from a comparison of this rate with the observed
thickness of stratified rocks on the earth's surface.
lloio to Ultimate tlie Thichnesa of the Sedimentari/ Hocks. —
The sedimentary rocks, of which the earth's crust is mainly com-
posed, consist, according to Sir Charles Lyell's classiHcation, of
fourteen great formations, of which the most ancient is the Lati-
i-cntinn, and the most recent the Post-tertiary; with thirty im-
portant subdivisions, each of which again consists of a more or
less considerable number of distinct beds or strata. Thus, the
Silurian formation is divided into Upper and Lower Silnriaa,
each characterized by a distinct set of fossil remains; and the
Upper Silurian again consists of a large number of separate
beds, such as the Wenlock Limestone, the Upper Llandovery
Sandstone, the Lower Llandovery Slates, etc., each usually char-
acterized by ft difference of mineral composition or mechaQical
structure as well as by some peculiar fossils. These beds and
formations vary greatly in extent, both above and beneath the
Bclunll V going on now ; lint if no elevnwry forces were nt vrovls, ihe rnie of (leonthi-
tioti would cui'tniiiljr dimiuLili aa iIjb tnoiintaing »era lowered and tlio elope of Ibe
ground ererywliore rendered 6niter. TliU would follow not onlv from the ditniniihed
power of min and rirors, but bwniisa the climnle would beromB more iinifbmi, ths
ninfall probnbly less, nnd no rocLy pcnks would be left lo be frncliireJ nnd liroken np
b; iho nciion of frosts, Ii ii eerlnin, bowcvar, tlint no conilncnl Iidh ever romoined
long iiibjecl to tlie influences of ttena Jation alone ; fur, as we hnvo Bccn in our uxth
clinpMr, elevation and depreuion linve nlirnyi been going on in one pnrt or oilier of
tb« •urface.
Chap.X.] the EARTH'S AGE. 207
surface, and are also of very varioas thicknesses in different lo-
calities. A thick bed or series of beds often thins out in a
given direction, and sometimes disappears altogether, so that
two beds which were respectively above and beneath it may
come into contact. As an example of this thinning-out, Amer-
ican geologists adduce the Palaeozoic formations of the Appa-
lachian Mountains, which have a total thickness of 42,000 feet,
but as they are traced westward thin out till they become only
4000 feet in total thickness. In like manner, the Carbonifer-
ous grits and shales are 1800 feet thick in Yorkshire and Lan-
cashire, but they thin out southward, so that in Leicestershire
they are only 3000 feet thick; and similar phenomena occur
in all strata and in every part of the world. It must be ob-
served that this thinning-out has nothing to do with denuda-
tion (wliich acts upon the surface of a country so as to produce
great irregularities of contour), but is a regular attenuation of
the layers of rock, due to a deficiency of sediment in certain
directions at the original formation of the deposit. Owing to
this thinning-out of stratified rocks, they are, on the whole, of far
less extent than is usually supposed. When we see a geological
map showing successive formations following each other in long
irregular belts across the country (as is well seen in the case of
the Secondary rocks of England), and a corresponding section
showing each bed dipping beneath its predecessor, we are apt
to imagine that beneath the uppermost bed we shall find all the
others following in succession like the coats of an onion. But
this is far from being the case, and a remarkable proof of the
narrow limitation of these formations has been recently obtained
by a boring at Ware through the Chalk and Ganlt clay, which
latter immediately rests on the Upper Silurian Wenlock Lime-
stone, full of characteristic fossils, at a depth of only 800 feet.
Here we have an enormous gap, showing that none of earlier
Secondary or late Palaeozoic formations extend to this part of
England, unless, indeed, they had been all once elevated and
entirely swept away by denudation.*
* The follo^iing stAtement of the depths at which the Pnloeozoic formations have
been reached in various localities in and around London was given by Mr. H. B.
Woodward in his address to the Norwich Greological Society in 1S79 :
fi08 ISLAND LIFE. [Past I.
But if we corsider liow such deposits are now forming, wc
eliall find tiiat the thinning-out of the beds of each formation,
and tlicir restriction to irregnlar bands and patches, is exactly
what we should expect. The enormous cjuantity of sedioient
continually poured into the eea by rivers gradually subsides to
the bottom as soou ss the motion of tiie water is checked. All
the heavier material must be deposited near the shore or in
those areas over which it is first spread by the tides or currents
of the ocean ; while only the very tine mud and clay arc carried
out to considerable distances. Tims all stratified deposits will
form most quickly near the shores, and will thin out riipidly at
greater distances, little or none being formed in the depths of
tlie great oceans. This important fact was demonstrated by tlie
specimens of sea-bottom examined during the voyage of the
CliaUenger, all the " shore-depositfi " being usually confined with-
in a distance of one hundred or one hundred and fifty miles
from the coast, while the "deep-sea" deposits are either purely
organic, being formed of the calcareous or siliceous slceletons of
Globigerime, radiolarians, and Diatomaceip, or are clays formed
of undissolved portions of these, together with the disintegrated
or dissolved materials of pumice and volcanic dust, which, being
very light, are carried by wind or by water over the widest
oceans.
From the preceding considerations we shall be better able to
appreciate the calculations as to the thickness of stratified de-
posits made by geologists. Professor Ramsay lias calculated
that the sedimentary rocks of Britain alone have a totjil maxi-
mum thickness of 72,600 feet ; while Professor Ilaughton, from
a survey of the whole world, estimates the maximnm thicknesa
L}erp Wtlh Ihrovyh ike Terliarg and Cretareoui Formatimu.
Harwich nt 1032 feet I'euclied rnibntiiferoUH Hock.
Kenliih Tonn "I1U " " Olil Kcd Snndtione.
ToUenham Conn Koail " 1064 " " Ueronian.
BlacknaU " 10O4 " " Devonum orOIJ Red Snndstone.
Ware " flOO " " Silurinn (Weiilock Plialc).
We thus Rni] that over a wide nrea, extonding from LonJon lo W'ni'o niid Hanrieh,
the nhola oS Llie rurinnlionB TrDni Ilia OaJJre to the I'enninn nrc wnnliiig, the Creinceoua
railing on iho CnrbonireroDa or older Pnlnozoic rocki ; nnd tlie inme deficieni^j ex-
Iciidi nentsa to Belgium, where the TortJsij bods are foitnd rwling on Cnrbonifuwa
at II dc|>lh ul kfs than 410 feel.
Chap.X.] TUE EARTH'S AGE. 209
of the known stratified rocks at 177,200 feet. Now these max-
immn thicknesses of each deposit will have been produced only
where the conditions were exceptionally favorable, either in deep
water near the mouths of great rivers, or in inland seas, or in
places to which the drainage of extensive countries was con-
veyed by ocean currents; and this great thickness will necessa-
rily bo accompanied by a corresponding thinness, or complete
absence of deposit, elsewhere. IIow far the series of rocks found
in any extensive area, as Europe or North America, represents
the wliole series of deposits which have been made there we
cannot tell ; but there is no reason to think that it is a very in-
adequate representation of their maximum thickness, though it
undoubtedly is of their extent and bulk. When we see in how
many distinct localities patches of the same formation occur, it
seems improbable that the whole of the deposits formed during
any one period should have been destroyed, even in such an area
as Europe, while it is still more improbable that they should be
so destroyed over the whole world ; and if any considerable por-
tion of them is left, that portion may give a fair idea of their
average, or even of their maximum, thickness. In his admira-
ble paper on " The Mean Thickness of the Sedimentary Rocks," *
Dr. James CroU has dwelt on the extent of denudation in di-
minishing the mean thickness of the rocks that have been
formed, remarking, " Whatever the present mean thickness of
all the sedimentary rocks of our globe may be, it must be small
in comparison to the mean thickness of all the sedimentary
rocks which have been formed. This is obvious from the fact
that the sedimentary rocks of one age are partly formed from
the destruction of the sedimentary rocks of former ages. From
the Laurentian age down to the present day the stratified rocks
have been undergoing constant denudation." This is perfectly
true, and yet the mean thickness of that portion of the sediment-
ary rocks which remains may not be very different from that of
the entire mass, because denudation acts only on those rocks
which are exposed on the surface of a country, and most largely
on those that are upheaved ; while, except in the rare ease of an
* Geolofjical Magazine, Vol. VIII., March, 1871.
14
910
ISLANH LIFE.
[P*IIT L
extensive formation being quite horisontid, and wliolly exposed
to the seu or to tlio atmospiierc, (lenudntion can have no tenden-
cy to diminish the thickness of any entire deposit.' ITnlesa,
tlierefore, a f-oi'ination is completely destroyed by dcnudaliou in
every part of the world {a thing very improbable), we may have
in existing roeks a not \cry inadcqnate representation of the
mean thickness of all that Jiavo been formed, and even of the
innximiim thickness of the larger portion. This will be the
more likely because it is almost certain that many rocks con-
temporaneously formed are counted by geologist* as distinct
formations whenever they differ in lithological character or in
organic remains. Bat we know that limestones, sandstones, and
shales are always forming at tiie same time; while a great dif-
ference in organic remains may arise from comparatively slight
changes of geographical features, or from difference in the depth
or purity of the water in which the animals lived.'
Ifow to Eatimate the Avera</e Rat^ of Deposition of the Sed-
imentary liocks. — But if we take the estimate of Profrasof
Ilanghton (177,200 feet), which, as we have seen, is probably ex-
cessive, for the maximum thickness of the sedimentary rocks of
the globe of all known geological ages, can we arrive at any es-
timate of the rate at which tliey were formed! Dr. CroU lias
attempted to make such an estimate, hut he has taken for liis
basis the menu thickness of the rocks, which we hare no means
whatever of arriving at, and which he guesses, allowing for den-
udation, to be ecjunl to the maximum thickness as measured by
geologists. The land area of the globe is, according to Dv. Croll,
' Mr. C. Lloyd Moignn lm» ivell illujiiniieJ ihis poinl liy comparinp th* eenornllj
tilicdnp simta denuded on iheir cilgca to n librar; in wliirh n fire Unit ocied on tiM
esiKiud edgei if ilie books, doiniyii'g n giiaii Tnnis ot llientiiiri!, but lenvlnE n por-
tion c>r«nL-li b"ok in '«» ptnccwlikh ponion ra]>n>»ciii3 ibeibickiiesi,but nut ibe aiie,
of the book {dtoloijicat Maagxiiir.. 1878, p. nil).
' ProTussor J, yonng iliinki it blKbly probnUe ibnt "iho I^oivcr Greensnnd !■
contempornncoui wiili jmrt or iho Clinlk, co wore pnrts of ilie Woolden ; nny, even
oflbe Purbeck n pniiiun mual have bean formiiig w|iile the CrtftnceouB sea niLs gnul-
iinll; d«e|ieninB uvuibniirtl und tveslwnrd." Yet llie«e ilejiosits nra nhrnys uminged
naccesMvely, nnd their sevaml ibieknesiea added togelbor to obliiin tiie lotnl lliiok-
ne<s of itie formntiont of tlie couiirry. (9m Fresideiiliui Addrasi, Sect. C. Britidi
Aasociniioii, IS 'IS.)
Chap.X.] the EARTH'S AGE. 211
57,000,000 square miles, and he gives the coast-line as 116,000
miles. This, however, is, for onr purpose, rather too much, as it
allows for bays, inlets, and the smaller islands. An approxi-
mate measurement on a globe shows that 100,000 miles will be
nearer the mark, and this has the advantage of being an easily
remembered even number. The distance from the coast to
which shore-deposits usually extend may be reckoned at about
one hundred or one hundred and fifty miles, but by far the
larger portion of the matter brought down from the land will
be deposited comparatively close to the shore ; that is, within
twenty or thirty miles. If we suppose the portion deposited
beyond thirty miles to be added to the deposits within that dis-
tance, and the whole reduced to a uniform thickness in a direc-
tion at right angles to the coast, we should probably include all
areas where deposits of the maximum thickness are forming at
the present time, along with a large but unknown proportion of
surface where the deposits were far below the maximum thick-
ness. This follows, if we consider that deposit must go on very
unequally along different parts of a coast, owing to the distance
from each other of the mouths of great rivers and the limita-
tions of ocean currents; and because, compared with the areas
over which a thick deposit is forming annually, those where
there is little or none are probably at least twice as extensive.
If, therefore, we take a width of thirty miles along the whole
coast-line of the globe, as representing the area over which de-
posits are forming, corresponding to the maximum thickness
as measured by geologists, we shall certainly over- rather than
under-estimate the possible rate of deposit.'
' As by far the larger portion of the denuded matter of the globe passes to the sen
through comparatively few great rivers, the deposits must often be confined to very
limited areas. Thus the denudation of tiie vast Mississippi basin must be almost aU
deposited in a limited portion of the Gulf of Mexico, that of the Nile within a small
area of the Eastern Mediterranean, and that of the great rivers of China — the Iloang
Ho and Yang-tse-kiang — in a small portion of the Eastern Sea. Enormous lengths
of coast, like those of Western America and Eastern Africa, receive very scanty de-
posits; so that thirty miles in width along the whole of the coasts of tiie globe will
probably give an area greater than that of the area of average deposit, and certainly
greater than that of maximum deposit, which is the basis on which I have here made
my estimates. In the cose of the Mississippi, it is stated by Count Pourtales that
218
ISLAND LIFE.
{Ptasl.
Now a coast-line of 100,000 miles with a widtli of 30 gives an
area of 3,UOO,000 eqiiare miles, on wliieli the denuded matter of
the whole land urea of 57,000,000 eijuare miles is deposited. As
these two areas ate as 1 to 19, it follows that deposition, as meas-
ured by maximuiu thickness, goes on at least nineteen times as
fast as denudation — probably very much faster. Uut the mean
rate of denudation over the whole earth is about one foot in
lliree thousand years ; therefore the mte of maximum deposition
will be at least nineteen feet in the same time ; and as the total
inaximam thickness of all the stratified rocks of the globe is, ac-
eording to Professor Hangliton, 177,200 feet, the time reijiiired
to produce this thickness of rock at the present rate of denuda-
tion and deposition is only 28,000,000 years."
T/ie Hate of Geological C'fiange Prohahhj Greater in very lie-
mote Times. — The opinion that denudation and deposition went
on more rapidlj'in early times owing to the frequent occurrence
of vast convulsions and cataclysms was strenuously opposed by
Sir Charlea Lyell, who so well showed that causes of the very
same nature as those now in action were sufficient to account for
all the phenomena presented by the rocks throughout the whole
series of geological formations. Kut while upholding the sonnd-
ntoiiK tlie plfltenu between ilie momh of [lie river nnd Ihe floiirliorn extremitrof Ilor.
idn, Tur Itvo liundred nnil llfly miles in niilth,lho boilom consisls ofclnr with some
dnnil nnd lut few Ithiiopods ; but beyond this distance iho noiindingB brought ap el-
tlier KhUopod fhelli olune, or these mixed niih coml innd, Nullipons), and other
calcareoni organisms (Diina'i "Manual of Geuloe;," Sd ed., p. GT1J. It i» probable,
therefore, that n birgo proponlon of the entire moM of lediment brouglit down bj
tlio Mississippi ii deposiied on tlio IJtnited area above indicated.
Professor Dunn fitrtber remmki, "Over inteiior ocennie lasina, na ivcl] ns ofTa
tonsi in quiet depllis, fifteen or tnenly fiiihoms and beyond, tho deposila are mostly
uffine silt, fliled Kir lanking line nrf[illnc«oiisrovk>,nsihnles or slates. When, hoir.
ever, the depth of ilio occnn fulls off below a hundred fjiilionu, the dqiosiiion of silt
in our existing oceans motlly censes, unlcu In the cnso of a gieat bank along the
lionlerorni
' From tlie «i
million jenrt for the duration nl illogical lime; but be ai
•ntiposing tliG prodacts of denudation to be uniromily spread ov
lorn instead of over n nnrrow bell ncnr the consis — a supposilioi
ir Ilnughlon Ci
of two h nnd red
this CDnclasion by
tlie whole ita-l/ol-
inlirely opposed in
■II the kiinun faeis, nnd which had been eiiown by Dr. Croll Are yenn previously to
be altngetber erroneauf. (Sec Nalyre. Vol. XVIJI., p. 3G8, nbere frofossor Uaugh-
ton's |<i>[>ei' is i^ven as read bcfiirc the Itoynl Society.)
Ohap.X.] the EAUTH'S AGE. 213
ness of the views of the ^^ unif ormitarians " as opposed to the
" convulsionists," we must yet admit tliat tliere is reason for be-
lieving in a gi*adaally increasing intensity of all telluric action
as we go back into past time. This subject has been well treated
by Mr. W. J. SoUas,* who shows that if, as all physicists main-
tain, the sun gave out perceptibly more heat in past ages than
now, this alone would cause an increase in almost all the forces
that have brought about geological plienomena. With greater
heat there would be a more extensive aqueous atmosphere, and
a greater difference between equatorial and polar temperatures ;
hence, more violent winds, heavier rains and snows, and more
powerful oceanic currents, all producing more rapid denudation.
At the same time, the internal heat of the earth being greater,
it would be cooling more rapidly, and thus the forces of con-
traction— which cause the upheaving of mountains, the eruption
of volcanoes, and the subsidence of extensive areas — would be
more powerful and would still further aid the process of denu-
dation. Yet again, the earth's rotation was certainly more rapid
in very remote times, and this would cause more impetuous
tides and still further add to the denuding power of the ocean.
It thus appears that as we go back into the past, all the forces
tending to the continued destruction and renewal of the earth's
surface would be in more powerful action, and must, therefore,
tend to reduce the time required for the deposition and upheav-
al of the various geological formations. It may be true, as many
geologists assert, that the changes here indicated are so slow
that they would produce comparatively little effect within the
time occupied by the known sedimentary rocks; yet, whatever
effect tliey did produce would certainly be in the direction here
indicated, and as several causes are acting together, their com-
bined effect may have been by no means unimportant. It must
also bo remembered that such an increase of the primary forces
on whicli all geologic change depends would act with great ef-
fect in still further intensifying those alternations of cold and
warm periods in each hemisphere, or, more frequently, of exces-
sive and equable seasons, which have been shown to be the re-
•
' See Geological MagcLziM for 1877, p. 1.
314
ISLAXD UPE.
Stilt of astroDouiical combined with geograpliical rerolntloDs;
and this would again increase the rapidity of denudation and
depofiition, and tUua still fnrtlier reduce the time required for
tbe production of the known eedimentary rocts. It k evident,
therefore, that tlieee various considerations all combine to prove
that, in supfwaing that the rate of denudation has been on tbc
average only what it is now, we are almost certainly overesti-
mating the time re(inired to have prodnced the whole scries of
forniatione from the Cambrian upwards.
Value of the Preceding Ultimate of Oeological Time. — It is
not, of course, supposed that the calculation here given makes
any approach to accuracy, but It is believed that it does indicate
the order of magnitude of the time required. We have a certain
number of data which are not guessed, but the result of actual
racasuremeut; such are, the amount of solid matter carried down
by rivers, the width of the belt within which this matter is miiiu-
ly deposited, and the maximum tbickne^ of the known stratitied
rucks.' A considerable but miknown amount of denudation is
effected by the waves of the ocean eating away coast-lines. This
was once thought to be of more importance than sobacrial denu-
dation, bnt it is now believed to be comparatively slow in its ac-
tion.' Whatever it may be, however, it adds to the rate of for-
mation of new strata, and its omission from the calculation is
again on the side of making the lapse of time greater rather than
lees than the trne amount. Even if a considerable modification
' Tn lii> reply to Sir W. Thomson, I'mfeimr Huxley owmBfrf one foot iti n lliou-
Hniiil .veori oa a not improbibla raia of (lepositlon. Tlie nbuve u'timntu inilirnics a
fur lilglicr rate ; and tliia fullowt fr<>m llie «cll-nicGniiineil fuel that ibc area of depo-
*ilinn i« many ilmca imnller ll>nn ilie nron of denudniion.
' Dr. Croll and ProfoMr Geiki« havt shomi tlmt mnrine denudation is very small
In amnunt u com)iaTed niili labneriiil, lince it acts only locnily on tlie tJje cf the
lanil, wliercaa the tnllor acts over every fi>ot of the nuface. Mr. W. T. lllnnfoid ar-
Bueit ihnl the dtflercnce is ilill erenier in tropicnl than in icmpernie laliludes, and ar-
rive* Dl the concliiiinn that "if over Ilriiish Indiii the effects or marine lo those of
freiih-wi>t«r denudation in removing tho roclts of the country be estimated at 1 to
100, I Uilieve that the result of marina action wiH ba grenily overstated "("Geoli^ey
and Zoology of Ahy»»inia," p. I ns, note). Now, as our estimate of the mle of »ulw
oerial deiiucjniion cannot pretend lo any jireciiio nccuracy, we nro justificil in neglect-
i>i|t marine denudation allogvilior. e»]>ecially na we linvc no merhod of Bstimaiin({ It
For ilia iihole earth witli any approach to coirGctnesj.
Chap,X.] the rate of ORGANIC CHANGE. 215
should be needed in some of tlie assumptions it lias been neces-
sary to make, the result must still show that, so far as the time re-
quired for the formation of the known stratified rocks, the hun-
dred million years allowed by physicists is not only ample, but
will permit of even more than an equal period anterior to the
lowest Cambrian rocks, as demanded by Mr. Darwin — a demand
supported and enforced by the arguments, taken from indepen-
dent standpoints, of Professor Huxley and Professor Ramsay.
Organic Modification Dependent on Change of Conditions, —
Having thus shown that the physical changes of the earth's sur-
face may have gone on much more rapidly and occupied much
less time than has generally been supposed, we have now to in-
quire whether there are any considerations which lead to the
conclusion that organic changes may have gone on with corre-
sponding rapidity.
Tliere is no part of the theory of natural selection which is
more clear and satisfactory than that which connects changes of
specific forms with changes of external conditions or environ-
ment. If the external world remains for a moderate period un-
changed, the organic world soon reaches a state of equilibrium
througli the struggle for existence; each species occupies its
place in nature, and there is then no inherent tendency to
change. But almost any change whatever in the external world
disturbs this equilibrium, and may set in motion a whole series
of organic revolutions before it is restored. A change of climate
in any direction will be sure to injure some and benefit other
species. The one will consequently diminish, the other increase,
in number; and the former may even become extinct. But the
extinction of a species will certainly affect other species which
it either preyed upon, or competed with, or served for food;
while the increase of any one animal may soon lead to the ex-
tinction of some other to which it was inimical. These changes
will in their turn bring other changes; and before an equilibrium
is again established the proportions, ranges, and numbers of the
species inhabiting the country may be materially altered. The
complex manner in which animals are related to each other is
well exhibited by the importance of insects, which in many
parts of the world limit the numbers or determine the very ex-
ISLAND LIPE.
[Paw I.
isteiice of some of tlie Itigticr animals. Mr, Dai-win savs, " Per-
haps Paraguay offers the most cnrious instance of tliis ; for here
neither cattle nop horses nor dogs have ever nm wild, though
tliey swai-Li southward and northward iira wild state ; and Aza-
ra and Ketiggcr have shown that this is caused by tlie greater
numbor in Paragnay of a certain fly which lays its eggs in the
navels of these animals wlien first born. The increase of these
liiee, numei'oiia as tliey are, must be habilnally checked by some
means, probably by other parasitic insects. Hence, if certain in-
sectivorous birds were to decrease in Paraguay, tlie parasitic in-
sects would probably increase; and this would lessen llie nnm-
ber of navel-frequenting flies ; then cattle and lioraea would run
wild ; and this would certainly alter (as, indeed, I liave observed
in parts of Sonth America) the vegetation ; this, again, would
largely affect the insects, and this, as we have seen in Stafliord-
shire, the insectivorous birds, and so onward in ever-increasing
circles of complexity."
Geographical changes wonid be still move important, and it is
almost impossible to exaggerate the modiflcations of the organic
world that might result from them. A subsidence of land sep-
arating a large island from a continent would affect the animals
and plants in a variety of ways. It would at once modify the
climate, and so produce a series of changes from tJiis cause alone ;
but moi-e important would be its effect by isolating small groups
of individuals of many species, and tlins altering their relations
to the rest of the organic world. Many of these would at once
be exterminated, while others, being relieved from competition,
might flonrish and become modified into new species. Even
more striking would be the effects when two continents, or any
two land areas which had been long separated, were united by an
upheaval of tlio strait which divided them. Numbers of ani-
mals would now be brouglit into competition for tlie first time.
New enemies and new competitors would appear in every part
of the country; and a struggle would commence which, after
many fluetnations, would certainly result in tho extinction of
some species, the moditlcation of others, and a considerable al-
teration in llie proportionate numbers and the geograpjiical dis-
tribution of almost all.
Chap.X.] the rate of ORGANIC CHANGE. 217
Any otlier changes which led to the intermingling of species
whose ranges were usually separate would produce correspond-
ing results. Thus, increased severity of winter or summer tem-
perature, causing southward migrations and the crowding to-
gether of the productions of distinct regions, must inevitably
produce a struggle for existence which would lead to many
changes both in the characters and the distribution of ani-
mals. Slow elevations of the land would produce another set of
changes, by affording an extended area in which the more domi-
nant species might increase their numbers ; and, by a greater
range and variety of Alpine climates and mountain stations, af-
fording room for the development of new forms of life.
Geographical Mutations as a Motive Power in Bringmg about
Organic Changes, — Now, if we consider the various geographical
changes which, as we have seen, there is good reason to believe
have ever been going on in the world, we shall find that the
motive power to initiate and urge on organic changes has never
been wanting. In the first place, every continent, though per-
manent in a general sense, has been ever subject to innumerable
physical and geographical modifications. At one time the total
area has increased, and at another has diminished ; great plateaus
have gradually risen up, and have been eaten out by denudation
into mountain and valley ; volcanoes have burst forth, and after
accumulating vast masses of eruptive matter have sunk down
beneath the ocean, to be covered up with sedimentary rocks, and
at a subsequent period again raised above the surface ; and the
loci of all these grand revolutions of the earth's surface have
changed their position age after age, so that each portion of
every continent has again and again been sunk under the ocean
waves, formed the bed of some inland sea, or risen high into
plateaus and mountain-ranges. How great must have been the
effects of such changes on every form of organic life ! And it is
to such as these we may perhaps trace those great changes of
the animal world which have seemed to revolutionize it, and
have led us to class one geological period as the age of reptiles,
another as the age of fishes, and a third as the age of mammals.
But such changes as these must necessarily have led to re-
peated unions and separations of the land masses of the globe,
S18
ISLAND LIFE.
[P*B» I.
joining together continents wliicli were before divided, and
breaking up others into great islands or extensive archipelagoes.
Such alterations of the means of transit would probably affect
the organic world even moi'e profoundly than tlie changes of
area, of altitude, or of climate, since they afforded the means, at
long intervals, of bringing the most diverse forma into competi-
tion, and of spreading all the great animal and vegetable types
widely over the globe. But the isolation of considerable masses
of land for long periods also afforded the means of preservation
to many of the lower types, which tlius had time to beeome
modified into a variety of distinct forms, some of which became
8o well adapted to special modes of life that they have continued
to exist to the present day, thus affording us examples of the
life of early ages which would probably long since have becouio
extinct, had they been always subject to the competition of the
more highly organized animals. As examples of sncli excessive-
ly archaic forms, we may mention the mnd-tishes and the ganoids,
coiitiued to limited fresh-water areas : the frogs and toads, wbioh
still maintain theniselvcB vigorously in competition with higher
forms; and among mammalB the Ornithorhynchns and EchiduR
of Auatralia; the whole oi-der of Marsiipiala — which, out of
Australia, where they are (^uite free from competition, only exist
abundantly in Sonth America, which was certainly long isolated
from the nortliern continent; the Insoctivora, which, though
widely scattered, are generally noetnrnul or subterranean in their
habits; and the I^emurs, which are most abundant in Madagas-
car, where they have long been isolated, and almost removed
from the comjictilion of higher forms.
Climatal Jieco/utions as an A(/erit in Producing Organic
Cfitini/c. — The geographical and geological changes we have
been considering are probably those which have been most ef-
fective in bringing abont the great features of the distribution
of animals, as well us the larger movements in the development
of organized beings; b[it it is to the alternations of warm and
cold, or of unifortn and excessive climates — of almost perpetual
spring in arctic as well as in temperate lands, with occasional
phases of cold culminating at remote intervals in glacial epochs
— that wo must impute some of the more remarkable cbiinges
Chap.X.] THb RATE OF ORGANIC CHANGE. 219
both in the specific characters and in the distribution of organ-
isms.* Although the geological evidence is opposed to the be-
lief in early glacial epochs except at very remote and distant in-
tervals, there is nothing which contradicts the occurrence of re-
peated changes of climate, which, though too small in amount
to produce any well-marked physical or organic change, would
yet be amply sufficient to keep the organic world in a constant
state of movement, and which, by subjecting the whole flora and
fauna of a country at comparatively short intervals to decided
changes of physical conditions, would supply that stimulus and
motive power which, as we have seen, is all that is necessary to
keep the processes of "natural selection" in constant operation.
The frequent recurrence of periods of high and of Jow eccen-
tricity must certainly have produced changes of climate of con-
siderable importance to the life of animals and plants. During
periods of high eccentricity with summer in perihelion, that
season would be certainly very much hotter, while the winters
would be longer and colder than at present ; and although geo-
graphical conditions might prevent any permanent increase of
snow and ice even in the extreme North, yet we cannot doubt
that the whole Northern Hemisphere would then have a very
different climate than when the changing phase of precession
brought a very cool summer and a very mild winter — a perpet-
ual spring, in fact. Now such a change of climate would cer-
tainly bo calculated to bring about a considerable change of
species^ both by modification and migration, without any such
decided change of type^ either in the vegetation or the animals,
that we could say from their fossil remains that any change of
climate had taken place. Let us suppose, for instance, that the
climate of England and that of Canada were to be mutually ex-
changed, and that the change took five or six thousand years to
bring about ; it cannot be doubted that considerable modifications
in the fauna and flora of both countries would be the result, al-
though it is impossible to predict what the precise changes would
' Agnssiz appears to have been the first to suggest that the principal epochs of life-
extermination were cpoclis of cold ; and Dana thinks that two at least such epochs
may be recognized, at the clo}»e of the Palieozoic and of the Cretaceous periods, to
which we may add tlie hist ghicial epoch.
320 ISLAND LIFE. [Paki Z
be. We call safely say, however, that some speeiea wonld stand
the change better than otlierci, nliile it is highly probable tlint
some ■would be actually beuelited by it, and others would bo
injured. 13nt the benefited would certainly increase and the
injured decrease in consequence, and thns ft series of changes
wonld be initiated that might lead to most important rcBiilts.
Again, we are sure that some species would become modified in
adaptation to the change of climate more readily than others,
and these modified species would therefore increase at the ex-
pense of others not so readily modified ; and hence would arise,
on the one hand, extinction of species, and, on the other, the pro-
dnction of new forms.
But thi^ is the very least amount of change of climate that
would certainly occni- every 10,500 years when there was a high
eccentricity, for it is impossible to doubt that a varying distance
of the sun in enmmer from 86 to 89 millions of miles (which
is what occurred during — as supposed — the Miocene period,
850,000 yeara ago) would produce an important difference in
the summer temperature and in the actinic inliucuco of sunshine
on vegetation. For the intensity of the sun's rays would vary
as tilt) wjiiarc of the distance, or nearly as 74 to 98, so that the
earth wonld be actually receiving one fourth less sun heat dur-
ing summer at one time than at the other. An etjnally high
eccentricity occurred 2,500,000 years back, and, no doubt, was
often reached during etill earlier epochs, while a lower but still
very high eccentricity has frequently prevailed, and is probably
near its average value. Changes of climate, therefore, every
10,500 years, of the character above indicated and of varying
intensity, have been the rule rather than the exception in past
time; and these changes must have been variously modified by
changing geographical conditions so as to produce climatic alter-
ations in different directions, and giving to the ancient lands
either dry or wet seasons, storms or calms, equable or excessive
tenipenitures, in a variety of combinations of which the earth
perhaps affords no example under the present low phase of ec-
centricity and consequent slight inequality of sun heat.
J'reseiit Ct»uIition of the Earth one of Excepiionjd StahUlty
as ivt/ards Vli/nafe. — It will be seen by a reference to the dia-
Chap.X.] the rate of ORGANIC CHANGE. 221
gram at page 163 that during the last 3,000,000 years the eccen-
tricity has been less than it is now on eight occasions, for short
periods only, making up a total of about 280,000 years ; while
it has been more than it is now for many long periods, of from
300,000 to 700,000 years each, making a total of 2,720,000 years,
or nearly as 10 to 1. For nearly half the entire period, or
1,400,000 years, the eccentricity has been nearly double what it
is now, and this is not far from its mean condition. We have
no reason for supposing that this long period of 3,000,000 years
for which we have tables was in any way exceptional as regards
the degree or variation of eccentricity ; but, on the contrary, we
may pretty safely assume that its variations during this time
fairly represent its average state of increase and decrease during
all known geological time. But when the glacial epoch ended,
72,000 years ago, the eccentricity was about double its present
amount ; it then rapidly decreased till, at 60,000 years back, it
was very little greater than it is now, and since then it has been
uniformly small. It follows that, for about 60,000 years before
our time, the mutations of climate every 10,500 years have been
comparatively unimportant, and that the temperate zones have
enjoyed an exceptional stability of climate. During this time
those powerful causes of organic change which depend on con-
siderable changes of climate, and the consequent modifications,
migrations, and extinctions of species, will not have been at
work ; the slight changes that did occur would probably be so
slow and so little marked that the various species would be able
to adapt themselves to them without much disturbance; and
the result would be an epoch of exceptional stability of species.
But it is from this very period of eocceptional stability that we
obtain our only scale for measuring the rate of organic change.
It includes not only the historical period, but that of the Swiss
Lake dwellings, the Danish shell -mounds, our peat-bogs, our
sunken forests, and many of our superficial alluvial deposits —
the whole, in fact, of the iron, bronze, and neolithic ages. Even
some portion of the palaeolithic age and of the more recent
gravels and cave-earths may come into the same general period,
if they were formed when the glacial epoch was passing away.
Now throughout all these ages we find no indication of change
328
ISLAND LIFK.
of speciee, and biit little, comparatively, of migration. Wc tliuB
get an erroDeous idea of the permanence and aUihility of specijic
forms, due to tlie period immediately autecedent to oui- own
h&m^a period of exceptiontU permanence and ainhiliti/ as regards
climatic and geographical conditions.'
Date of Lodi Glacial Epochs and its Bearing on the Measure-
ment of Geological Time. — Dinictly we go back fi-oni this stable
period, wc come upon changes both in the forms and in the dis-
tribntion of species; and when we pass beyond the last glacial
epoch into the Pliocene period, we lind onrselves in a compara-
tively new world, surrounded by a considerable number of spe-
cies altogether different from any which now exist, together
■with niauy others which, though still living, now inhabit distant
regions. It seenie not improbable that what is termed the Pli-
ocene period was really the coining-on of the glacial epoch, and
tliis is the opinion of Professor Jules Marcou.' According to
our views, a considerable amount of geographical cliange must
have occnrred at the change from tlie Miocene to the Pliocene,
favoring the refrigeration of tlie Northern Hemisphere, and
leading, in the way already pointed out, to the glacial epoch
whenever a high degree of eccentricity prevailed. As many
reasons combine to make us fix the height of the glacial epoch
at the period of high eccentricity which occurred 200,000 yeara
back, and as the Pliocene period was proliably not of long dura-
tion, we must suppose the next great phase of very liigh cccen-
tpicity (860,000 yeare ago) to fall within the Miocene epoch.
Dr. Croll believes that this must have produced a glacial period,
but we have shown strong reasons for believing that, in concur-
rence with favorable geographical conditions, it led to uninter-
rupted warm climates in the temperate and northern zones.
' Tills view wns, I helicre, flnt put forlli hy myse\{ In n popor reiid bebre the Geo-
logical Section of ibe Briiiih Anocintion in ISCU, nnd iiitiKiiiieiiily in nn ariirle in
ffitfHn. Vol. I..p.4nt. ll WHS nl«> EtAi«d by Mr. S. B. K. Skeruliley )n liis "I'lij-a-
icnlSrslcta of ihe Univercc," p. aca (IS7S}; but we luth foiiiided iion ivlmt 1 now
cvaaidsr tiic emineoni dociriiio ihni nclunl einrini cpoclis rccuri'cd cncli 10,.iOO jaan
during period* of liigli wcentricirv,
' " Kxplicnlion d'uneSocandQ^diilon ds laC*rte GtfologiquedelnTorro"(ldTfi),
Chap.X.] measurement OF GEOLOGICAL TIME. 223
This, however, did not prevent the occurrence of local glacia-
tion wherever other conditions led to its initiation, and the
most powerful of such conditions is a great extent of high land.
Now we know that the Alps acquired a considerable part of
their elevation during the latter part of the Miocene period,
since Miocene rocks occur at an elevation of over 6000 feet,
w^hile Eocene beds occur at nearly 10,000 feet. But since that
time there has been a vast amount of denudation, so that these
rocks may fii-st have been raised much higher than we now find
them, and thus a considerable portion of the Alps may once
have been more elevated than now. This would certainly lead
to an enormous accumulation of snow, which would be increased
when the eccentricity reached a maximum, as already fully ex-
plained, and may then have caused glaciers to descend into the
adjacent sea, carrying those enormous masses of rock which are
buried in the Upper Miocene of the Superga in Northern Italy.
An earlier epoch of great altitude in the Alps, coinciding with
the very high eccentricity 2,500,000 years ago, may have caused
the local glaciation of the Middle Eocene period when the enor-
mous erratics of the Flysch conglomerate were deposited in the
inland seas of Northern Switzerland, the Carpathians, and the
Apennines. This is quite in harmony with the indications of
an uninterrupted warm climate and rich vegetation during the
very same period in the adjacent low countries, just as we find
at the present day in New Siealand a delightful climate and a
rich vegetation of Metrosideros, fuchsias and tree-ferns on the
very borders of huge glaciers, descending to within seven hun-
dred feet of the sea-level. It is not pretended that these esti-
mates of geological time have any more value than probable
guesses; but it is certainly a curious coincidence that two re-
markable periods of high eccentricity should have occurred at
such periods and at such intervals apart as very well accord with
the comparative remoteness of the two deposits in which un-
doubted sisjis of ice-action have been found, and that both these
are localized in the vicinity of mountains which are known to
have acquired a considerable elevation at about the same period
of time.
In the tenth edition of the "Principles of Geology," Sir
ISLAND LIFS.
Charles Lyell, taking tlie amount of change in the species of
inollusca as a guide, estimated the time elapsed since tlie com-
meuccment of the Miocene as one third that of tlie whole Ter-
tiary epoch, and the latter at one fourth that of geological time
since the Cambrian period. Professor Dana, on the other liaud,
estimates the Tertiary as only one fifteenth of the Mesozoic and
Paljeozoic combined. On the estimate above given, founded on
the dates of phases of high eccentricity, we shall arrive at about
four million years for the Tertiary epoch, and &i.\teen million
years for the time elapsed since the Cambrian, accoi-ding to Lyell,
or sixty millions according to Dana. The estimate arrived at
from the rate of denudation and deposition (twenty-eight million
years) is nearly midway between these, and it is, at al! events,
satisfactory that the various measures result in figures of the
same order of magnitude, which is all one can expect on so dif-
ficult and exceedingly speculative a subject.
The only value of such estimates is to define our notions of
geological time, and to show that the enormous periods of hun-
dreds of millions of years which have sometimes becu indicated
by geologists are neither necessary nor warranted by the facts
at our command; while the pi-esent result places ns more in
harmony with the calculations of physicists, by leaving a very
wide margin between geological time as defined by the fossilif-
erous rocks and that fur more extensive period which includes
all possibility of life upon the earth.
Vondiidimj iieincwhs. — In the present chapter I have endeav-
ored to show that, combining the measured i-ate of denudation
with the estimated thickness and probable extent of the known
scries of sedimentary rocks, we may arrive at a rude estimate of
the time occupied in the formation of those rocks. From hii-
other point of departure — that of the probable date of the Mio-
cene period as determined by the epoch of high eccentricity
supposed to have aided in the production of the Alpine glncia-
tiou during that period, and taking the estimate of geologists as
to the proportionate amount of change in the animal world since
that epoch — wo obtain another estimate of the duration of geo-
logicnl time, which, though founded on far less secure data, agrees
pretty nearly with the former estimate. The time thus arrived
^BQ^.
Chap.X.] MEASUliEMENT OF GEOLOGICAL TIME. 225
at 18 immensely less than the usual estimates of geologists, and
is so far within the limits of the duration of the earth as cal*
culated by Sir William Thomson as to allow for the develop-
ment of the lower organisms an amount of time anterior to the
Cambrian period several times greater than has elapsed between
that period and the present day. I have further shown that, in
the continued mutations of climate produced by high eccentric-
ity and opposite phases of precession, even though these did
not lead to glacial epochs, we have a motive power well calcu-
lated to produce far more rapid organic changes than have hith-
erto been thought possible; while in the enormous amount of
specific variation (as demonstrated in an earlier chapter) we have
ample material for that power to act upon, so- as to keep the
organic world in a state of rapid change and development pro-
portioned to the comparatively rapid changes in the earth's sur-
face.
We have now finished the series of preliminary studies of the
biological conditions and physical changes which have afiooted
the modification and dispersal of organisms, and have thus
brought about their actual distribution on the surface of the
earth. These studies will, it is believed, place us in a condition
to solve most of the problems presented by the distribution of
animals and plants, whenever the necessary facts both as to their
distribution and their affinities are sufficiently well known ; and
we now proceed to apply the principles we have established to
the interpretation of the phenomena presented by some of the
more important and best known of the islands of our globe,
limiting ourselves to these for reasons which have been already
suflSciently explained in our preface.
15
Part IL
INSULAR FAUNAS AND FLORAS
CHAPTER XI.
THE CLASSIFICATION OF ISLANDS.
Importance of I&lands in the Study of the Distribution of Organisms. — Classification
of Islands with lieference to Distribution. — Continental Islands. — Oceanic Islands.
In the preceding cliapters, forming the first part of our work,
we liave discussed, more or less fully, the general features pre-
sented by animal distribution, as well as the various physical
and biological changes which have been the most important
agents in bringing about the present condition of the organic
world.
We now proceed to apply these principles to the solution of
the numerous problems presented by the distribution of animals;
and in order to limit the field of our inquiry, and at the same
time to deal only with such facts as may be rendered intelligible
and interesting to those readers who have not much acquaintance
with the details of natural history, we propose to consider only
such phenomena as are presented by the islands of the globe.
Importance of Idands in the Study of the Distribution of
Organisms. — Islands possess many advantages for the study of
the laws and phenomena of distribution. As compared with
continents they have a restricted area and definite boundaries,
and in most cases their geographical and biological limits coin-
cide. The number of species and of genera they contain is
always much smaller than in the case of continents, and their
peculiar species and groups are usually well defined and strictly
limited in range. Again, their relations with other lands are of-
ten direct and simple, and even when more complex are far
easier to comprehend than those of continents ; and they ex-
hibit, besides, certain influences on the forms of life and certain
peculiarities of distribution which continents do not present, and
whose study offers many points of interest
230
ISLAND LIFE.
Vfxxt IL
In islands wc liave tlio facts of distriliuticni often presented
to lis in tlicir simplest forms, along with otliere which become
gmdnall^ more and more complex ; luid we are therefore able to
proceed step by step in the solution of the problems tlioj present.
But as in studying these problems we have uecessarilj to take
into acconnt tbc relations of the insular and continental faunas,
wc also get some knowledge of the latter, and acquire besides so
much command over the general principles which underlie all
problems of distribution that it is nut too mnch to say that when
we have mastered the difficuUies presented by the pecuHarittes
of island life we shail find it comparatively easy to deal with the
more complex and less clearly defined problems of continental
distribution.
Vlaasifii^tion ofhlamh with liefr-ivitee to Diniribution. — Isl-
ands have had two distinct modes of origin : they have cither
boon separated from continents of which they ^va but detached
fragments, or they have originated tn the ocean and have never
formed part of a continent or any large mass of land. This
difference of origin is fundameutal, and leads to a most im-
portant difference in their animal inhabitants; and we may
therefore first distinguish the two classes — oci-anic and conti-
nental islands.
Mr. Darwin appeare to have been the first writer who called
attention to the number and importance, both from n geological
and biological point of view, of oceanic islands, ]Ie showed
that with very few exceptions all the remoter islands of the
great oceans were of volcanic or coralline formation, and that
none of them contained indigenous mammalia or amphibia. lie
also showed the connection of these two phenomena, and inain-
taiucd that none of the islands bo characterized Iiad ever formed
part of a continent. This was quite opposed to the opinions of
llie Bcientilic men of the day, who almost all held the idea of
continental extensions, and of oceanic islandB being their frag-
ments, and it was long before Mr. Darwin's views obtained gen-
eral acceptance. Even now the belief still lingers; and we con-
tinually hear of old Atlantic or Pacific continents, of " Atlantis "
or "Lemuria,'' of which hypothetical lands many existing isl-
ands, atthnugli wholly volcanic, arc tliouglit to be iho reujnants.
Chap. XL] THE CLASSIFICATION OF ISLANDS. 231
We have already seen that Darwiii connected the peculiar geo-
logical structure of oceanic islands with the permanence of the
great oceans which contain them, and we have shown that sev-
eral distinct lines of evidence all point to the same conclusion.
We may therefore define oceanic islands as follows : Islands of
volcanic or coralline formation, usually far from continents, and
alwaj's separated from them by very deep sea ; entirely without
A indigenous land mammalia or amphibia, but with abundance of
birds and insects, and usually with some reptiles. This defini-
tion will exclude only two islands which have been sometimes
>^ classed as oceanic — Xew Zealand and the Seychelles. Kodri-
guez, which was once thought to be another exception, has been
shown by the explorations during the Transit of Venus Expedi-
tion to be essentially volcanic, with some upraised coralline lime-
stone.
CmitinenioX Inlands. — Continental islands are always more
varied in their geological formation, containing both ancient
and recent stratified rocks. They arc rarely very remote from
a continent, and they always contain some land mammals and
amphibia, as well as representatives of the other classes and
orders in considerable variety. They may, however, be divided
into two well-marked groups — ancient and recent continental
islands — the characters of which may be easily defined.
Recent continental islands arc always situated on submerged
banks connecting them with a continent, and the depth of the
intervening sea rarely exceeds 100 fathoms. They resemble the
continent in their geological structure, while their animal and
vegetable productions are either almost identical with that of
the continent, or, if otherwise, the difference consists in the pres-
ence of closely allied species of the same types, with occasionally
a very few peculiar genera. They possess, in fact, all the charac-
teristics of a portion of the continent, separated from it at a
recent geological period.
Ancient continental islands differ greatly from the preceding
in many respects. They are not united to the adjacent conti-
nent by a shallow bank, but are usually separated from it by a
depth of sea of a thousand fathoms or upwards. In geological
structure they agree generally with the more recent islands;
laL&ND LIFE.
[P»ltT U.
like them they poeseaa mammalia and amphibia, uenally in con-
eiderable abundance, as well aa all other claases of aniiuala ; but
these are higlilj peculiar, almost all being diatiiict species, and
many forming distinct and peculiar genera or families. They
arc also well characterized by the fragmentary nature of their
fauna, many of the most characteristic continental oi-ders or
families being quite unrepresented, while some of their animals
arc allied, nut to such forma as inhabit the adjacent continent,
but to others found only in remote parts of the world. This
very remarkable set of characters mark off the islands which
exhibit them as a distinct class, which often present the great-
est anomalies and most difficult problems to tlie student of dis-,
tribntion.
Oceanic Jdaiids. — The total absence of warm-blooded terres-
trial animals in an island otherwise well suited to maintain
them is held to prove that such island is no mere fragment
of any existing or submerged continent, but one that lias been
actually produced in mid-ocean. It is true that if a continental
island were to be comjileteiy submerged for a single day and
then again elevated, its higher terrestrial animals would be
all destroyed; and if it were situated at a considerable dis-
tance from land, it would be reduced to the same zoological
condition as an oceanic island. But such a complete snb-
roergeuce and re-elevation appears never to have taken place,
for there is no single island on the globe which has the phyei-
cal and geological features of a continental combined with
the roological features of an oceanic island. It is true that
some of the coral islands may be formed upon submerged lands
of a continental character, but we have no proof of this; and
even if it were so, the existing islands arc to all intents and pur-
poses oceanic.
We will now pass on to a consideration of some of the more
interesting examples of these three classes, beginning with oce-
anic islands.
All the animals which now inhabit such oceanic islands must
either themselvos have reached them by erossiug the ocean, or
be the descendants of ancestors who did so. lit us, then, see
what are, in fiict, the animal and vegetable inhnbitnnts of these
Chap. XL] THE CLASSIFICATION OF ISLANDS. 233
islands, and bow far their presence can be accounted for. We
will begin with the Azores, or Western Islands, because they
have been thoroughly well explored by naturalists, and in their
peculiarities aflFord us an important clew to some of the most
efficient means of distribution among several classes of animals.
234 ISLAND LIFE. [Pabt IL
CHAPTER XII.
OCEANIC ISLANDS.— THE AZORES AND BERMUDA.
The AzorkS) or Western Islands. — Position and Physicnl Featares. — Chief Zo-
ological Features of the Azores. — Birds.— Origin of the Azorean Bird Fauna. —
Insects of the Azores. — Land Shells of tlie Azores. — The Flora of the Azores. —
The Dispersal of Seeds. — Birds as Seed-camers. — Facilities for Dispersal of Azo-
rean Plants. — Important Deduction from the Peculiarities of the Azorean Faana
and Flora.
Bermuda. — Position and Physical Featui-es. — The Red Clay of Bermuda. — Zoology
of Bermuda. — Birds of Bermuda.— Comparison of the Bird Faunas of Bermuda and
tiie Azores. — Insects of Bermuda. — Land MoIIusca. — Flora of Bermuda. — Con-
cluding Remarks on the Azores and Bermuda.
We will commence our investigation into the phenomena pre-
sented by oceanic islands with two groups of the North Atlan-
tic, in which the facts are of a comparatively simple nature, and
such as to afford us a valuable clew to a solution of the more dif-
iicult problems we shall have to deal with further on. The
Azores and Bermuda offer great contrasts in physical features,
but striking similarities in geographical position. The one is
volcanic, the other coralline ; but both are surrounded by a wide
expanse of ocean of enormous depth, the one being about as far
from Europe as the other is from America. Both are situated
in the temperate zone, and they differ less than six degrees in
latitude, yet the vegetation of the one is wholly temperate, while
that of the other is almost tropical. The productions of the one
are related to Europe, as those of the other are to America, but
they present instructive differences; and both afford evidence of
the highest value as to the means of dispersal of various groups
of organisms across a wide expanse of ocean.
THE AZORES, OR WESTERN ISLANDS.
These islands form a widely scattered group, nine in number,
situated between 37° and 30° 40' N. lat., and stretching in a
CHAr. XII.]
OCEANIC ISLANDS.
SQuUieast and nortiiwest direction over a distance of iionHy 400
miles. Tlie largest of the islauds, San Miguel, is about 40 miles
long, mid is oue of tlio nearcet to Europe, being rather under
900 miles from the coast of Portugal, from which it la separated
hy an ocean 2500 fathoms deep. Tlic depth between tlie ieluTids
does not seem to be known, but tlio 1000-fatlioui line endoses
the whole group pretty olostly, while a depth of about 1800
—The liglit linl b1
Tho figures slio
ileptba in futlioni!.
L...... ^.
^^1 great depths render it in the highcBt dcgi-ee improbable that the
^^1 Azores have ever been united with the Earopcan continent;
^^H while their being wholly volcanic is eqnally opposed to the view
^^M of their liuviiig farmed part of an estensive Atlantis including
^^1 Madeira and the Canaries. The only exception to their volcanic
^^H etrnctiiro is the occurieuce in one small iijland only (Santa Ma-
ISLAND LIFE.
[Piax II.
ria) of Boiiic triai'ino deposits of Upper Miocene age — a fact
wLicli proves some alteralious of level, and perhaps a greater
extension of this island at some former period, but in no way
indii'atca a former nuion of the islands, or any greater extension
of the whole group. It proves, however, that the gronp is of
considerable antiquity, since it must date back to Miocene times ;
and this fact may be of importance in considering the origin and
peculiar features of the fiinna and flora. It thus appears that in
all physical features the Azores correspond strictly with oar
deHnition of " oceanic islands ;" while their great distance from
any other land, and the depth of the ocean around them, make
them typical examples of the class. We shonld therefore expect
them to be equally typical in their fauna and flora ; and this is
the case as regards the most important charaetenstics, although
in some points of detail they present exceptional phenomena.
Chief ZiKihiijlcal J'entnres of the Azores' — Tiie great feature
of oceanic islands — the absence of all indigenous land mammalia
and amphibia — is well shown in this group; and it is even car-
ried further, so as to include all terrestrial vertebrata, there being
no snake, lizard, frog, or fresh-water fish, although the islands
are sutticiently extensive, possess a mild and equable climate, and
are in every way adapted to support all these groups. On the
other hand, flying creatnres, as birds and insects, are abundant ;
and tliere is also one flying mammal — a small European bat. It
is true tliat i-abbits, weasels, rats and mice, and a email lizard
peculiar to Madeira and Teneriffe are now found wild in the
Azores, but there is good reason to believe that these have all
been introduced by liuman agency. The same may be said of
the gold-flsh and eels now found in some of tiie lakes, there be-
ing not a single fresli-waler fish which is truly indigenous to the
islands. When we consider that the nearest part of tlio gi-oup
is about BOO miles from Portugal and moi-e than 550 miles from
Madeira, it is not surprising that none of these terrestrial ani-
mals can have passed over sucti a wide expanse of ocean unas-
sisted by man.
' For mnai of ilie fiicW as t
In Mr. Goilmim'a vnliiabls ii
jmUs," by Frecleriik Ma Ciiiie
laionlogy oad botnn.roriheseiKlniidilm
. " Xnltiral Hi«lory of tliG A^orej, or W
idm-in, F.L.S., F.Z.S., etc., London. IB?
nU-
Chap. XII.] THE AZORES. 237
Let us now sec what animals are believed to have reached the
group by natural means, and thus constitute its indigenous fauna.
These consist of birds, insects, and land shells, each of which
must be considered separately.
Birds, — Fifty-three species of birds have been observed at the
Azores, but the larger proportion (thirty-one) are either aquatic
or waders — birds of great powei^s of flight, whose presence in
the remotest islands is by no means remarkable. Of these two
groups twenty are residents, breeding in the islands, while eleven
are stragglers, only visiting the islands occasionally, and all are
common European species. The land birds, twenty-two in num-
ber, are more interesting, four only being stragglers, while eigh-
teen are permanent residents. The following is a list of these
resident land birds :
1 . Common Buzzard Buteo vulgaris,
2. Long-eared Owl Asio otua,
3. Barn Owl Strixjiammea.
4. Blackbird Turdus merula,
5. liobin Erithacut rubecula,
6. Blackcap Sylvia airicapilla,
7. Gold-crest Regulus cristatus.
8. Wheat-ear Saxicola ctnanthe,
9. Grajr Wagtail Motacilla sulphurea.
1 0. Atlantic Chaffinch FnngiUa tintilion,
11. Azorean Ballfinch Pyrrhula murina,
1 2. Canary Serinus Canarius,
13. Common Starling Stumus vulgaris,
1 4. I.,esser Spotted Woodpecker Dryohates minor,
14. Wood -pigeon Columha palumbus.
IG. Rock-dove Columha livta,
17. Red-legged Partridge Caccabis rufa.
1 8. Common Quail Cotumix communis.
All the above-named birds are common in Europe and North
Africa except three — the Atlantic chaffinch and the canary,
which inhabit Madeira and the Canary Islands, and the Azorean
bullfinch, which is peculiar to the islands we are considering.
Origin of the Azorean Bird Fauna. — The questions we have
now before us are — how did these eighteen species of birds first
reach the Azores, and how are we to explain the presence of a
single peculiar species while all the rest are identical with Euro-
pean birds? In order to answer them, let us first see what
ISLAND LIFE.
CI'Airt II.
stragglers now actually visit the Azores from the nearest conti-
nents. The four Bpecies given in Mr. Ooduian'a list are tlie
kestrel, the oriole, tlio snow-bunting, and the hoopoe; but he
also tells lis that there are certainly others, and adds, "Scarcely
a storm occurs in spring or autntnn without bringing one or
more species foreign to the ishmds ; and I have frequently been
told that swallows, larks, grebes, and other species not referred
to here are not nncoininonly seen at those seasons of tJie
year."
We Iiave therefore every reason to believe that the biids
which are now residents originated as stragglers, which occa-
sionally fonnd a haven in these remote islands when driven ont
to sea by storms. Some of tlicm, no donbt, still often arrive
fron] the continent, bnt these cannot easily be distinguished as
new arrivals among those which are residents. Many facts men-
tioned by Mr. Godman show that this is the case. A barn
owl, much exhausted, Hew on board a whaling-ship when 500
miles Eonthwest of the Azores; and even if it had come froin
Madeira it must have travelled quite as far as from Portugal tu
the islands. Mr. Godniau also shot a single specimen of tlic
wheat-ear in Flores after a strong gale of wind ; and as no one on
the island knew the bird, it was almost certainly a recent arrival.
Subsequently a few wore found breeding in the old crater of
Corvo, a small adjacent island ; and as the species is not found
in any other island of the group, we may infer that this bird is
A recent immigrant in process of establisliing itself.
Another fact which is almost eonelnsive in favor of the bii-d-
population having arrived as stragglers is that they are most
abundant in the islands nearest to Eurepe and Africa. The
Azores consist of three divisions — an eastern, consisting of two
islands, St. Michael's and St. Mary's; a central, of five, Tercoira
Graciosa, St. George's, Pico, and Fayal ; and n western, of two,
Flores and Corvo. Now, had the whole group once been united
to the continent, or oven formed [wrts of one extensive Atlantic
island, wc should certainly expect the central group, which is
more compact and has a much larger area than all ihe rest, to
have the greatest nnmbor and variety of birds. Bnt the fact
that bird^ are most numerous in the eastern group, and diminish
Chap. XII.] THE AZORES. 23J)
as we go westward, is entirely opposed to this theory, while it
is strictly in accordance with the view that they are all strag-
glers from Europe, Africa, or the other Atlantic islands. Omit-
ting oceanic wanderers, and including all birds which have prob-
ably arrived involuntarily, the numbers are found to be forty
species in the eastern group, thirty-six in the central, and twenty-
nine in the western.
To account for the presence of one peculiar species, the bull-
finch (which, however, does not diflfer from the common Euro-
pean bullfinch more than do some of the varieties of North
American birds from their type-species), is not difficult, the
wonder rather being that there are not more pecuh'ar forms. In
our third chapter we have seen how great is the amount of in-
dividual variation in birds, and how readily local varieties be-
come established wherever the physical conditions are sufficient-
ly distinct. Now we can hardly have a greater difference of
conditions than between the continent of Europe or North Af-
rica and a group of rocky islands in mid-Atlantic, situated in
the full couree of the Gulf Stream and with an excessively mild
though stormy climate. We have every reason to believe that
special modifications would, soon become established in any ani-
mals completely isolated under such conditions. But tliey are
not, as a rule, thus completely isolated, because, as we have seen,
stragglers arrive at short intervals ; and these, mixing with the
residents, keep up the purity of the breed. It follows that only
those species which reach the Azores at very remote intervals
will be likely to acquire well-marked distinctive characters ; and
this appears to have happened with the bullfinch alone, a bird
which docs not migrate, and is therefore less likely to bo blown
out to sea, more especially as it inhabits woody districts. A few
other Azorean birds, however, exhibit slight diflferences from
their European allies.
There is another reason for the very slight amount of peculi-
arity presented by the fauna of the Azores as compared with
many other oceanic islands, dependent on its comparatively re-
cent origin. The islands themselves may be of considerable an-
tiquity, since a few small deposits, believed to be of Miocene
age, have been found on them ; but there can be little doubt that
ISLAND LIFE.
[PawIL
their present fauna, at all events as eoncernB the birds, bad its
origin since the date of the last glacial epoch. Eveu now ice-
bergs reach tlie latitude of the Azores only a little to the west-
ward; and when we consider the proofs of extensive ice-action
in North America and Europe, we can hardly doubt that these
islands were at that time surrounded with pack-ice, while their
own mountains, reaching 7600 feet high in Pico, would almost
certainly have been covered with perpetual snow and havo
sent down glaciei-s to the sea. They might then have had a
elimste almost as bad as that now endured by the Prince Ed-
ward Islands in the Southern llemisphere, nearly ten degrees
farther from the equator, wliere there are no land bii-ds what-
ever, although the distance from Africa is not much greater
tjjan that of the Azores from Europe, white the vegetation
is limited to a few alpine plants and mosses. This recent ori-
gin of the birds accounts, in a great measure, for their identity
with those of Europe, because, whatever change has occurred
must have been effected in the islands themselves, and in a time
limited to that which has elapsed since the glacial epoch passed
away.
//(«(■<.*» of the Azores. — Having thus found no difficulty in ac-
counting for the peculiarities presented by the birds of these
Islands, wo have only to see how far the same general principles
will apply to the insects and land shells. The buttcrliies, moths,
and hynienoptera are few in number, and almost all seem to be
common European si>ecies, whose presence is explained by tlie
same causes as those which have Introduced the birds. Beetles,
however, are more numerous, and have been better studied, and
these present some features of interest. The total nnmber of
species yet known is :il2, of which 17j are European ; but out
of these 101 are believed to have been introduced by human
agency, leaving seventy-four really indigenous. Twenty-three of
these indigenous &ix^cies are not found in any of the other Atlan-
tic islands, showing that tlicy have been introduced directly from
Europe by causes which have acted more powerfully here than
farther south. Besides these, there are thlity-six species not
found in Europe, of which nineteen are natives of JIadoira or
the Canaries, three are Anieriean, and fuiirtcen are altogether
Chap. XII.] THE AZORES. 241
pecnliar to the Azores. These latter are mostly allied to spe-
cies found in Europe or in the other Atlantic islands, while one
is allied to an American species, and two are so distinct as to
constitute new genera. The following list of these peculiar spe-
cies will be interesting :
CARABlDiE.
Anchomenus aptinoides Allied to a species from the Canaries.
Bembidium htsperus Allied to the European B. Icetum.
DlTIRCID^.
Agahua Godmanni, Allied to the European A, dispar.
COLTDlID-«.
Tarphius Wollastoni A genus almost peculiar to the Atlantic Islands.
Elate BiD.«.
Heteroderes Azorictts Allied to a Brazilian species.
Elastrus dolosus Belongs to a peculiar Madagascar genus.
Meltrid^.
Attains miniaticollis Allied to a Canarinn species.
Rhyncophora.
Phlatophagus variabilis Allied to European and Atlantic species.
Acalles Lh-oueti A Mediterranean and Atlantic genus.
Laparocerus Azoricus Allied to Madeiran species.
Asynonychus Godmanni. A peculiar genus, allied to Brachyderes of the
South of Europe.
Neocnemis occidentalis A peculiar genus, allied to the European genus
Strophosomus,
Heteromera.
Helops Azoricus Allied to U, vulcanus of Madeira.
Staphylinid*.
Xenomma melanocephala Allied to X.fiUforme from the Canaries.
This greater amount of speciality in the beetles than in the
birds may be due to two causes. In the first place, many of
these small insects have, no doubt, survived the glacial epoch,
and may, in that case, represent very ancient forms which have
become extinct in their native country ; and, in the second place,
insects have many more chances of reaching remote islands than
birds, for not only may they be carried by gales of wind, but
sometimes, in the egg or larva state, or even as perfect insects,
they may be drifted safely for weeks over the ocean, buried in
16
s^
ISLAXD LIFE.
[PaktIL
the liglit Btema of plants or in tlie solid wood of trees in wliicli
many of them undergo their trnnEformntions, Thoa wo may
explain the presence of three common South American epeciea
(two elaters and a longiuorn), ail wood-eaters, and tliereforo
liable to be occasionally hronght in Uoating timber by the Gnlf
Stream. But insects are also immensely more numcvoue in spe-
L-ies than are land birds, and tJieir ti-ansmission M'onid bo in most
cases qnitc invohintary, and not dependent on their own powers
of Hight.ns ^vitli birds; and tliiis the chances against iJiu same
species being frequently carried to the same island would be
considerable. If wo add to this the dependence of so many in-
sects on local conditions of climate and vegetation, and their
iiability to Ije destroyed by insectivorous birds, we shall see that,
although there may be a greater probability of insects as a whole
reaching the islands, the chances against any particular insect
arriving there, or against the same species arriving fitquently,
are mucli greater tlian in the case of birds. Tlie i-cstilt is that
(us compared with Britain, for example) the birds are propor-
tionately much more iinmcrous than the beetles; while the pe-
culiar species of beetles are innch more numerous than among
birds, both facts being quite in accordance with what we know
of the habits of the two f^roups. We may also remark that the
small size and obscure characters of many of the beetles render
it probable that species now supposed to be peculiar really in-
habit some parts of Europe or North America.
It is interesting to note that tlie two families which are pre-
eminently wood, loot, or seed eatere arc those which present the
greatest amount of speciality. Tlie two ElatcridsB alone exhibit
remote affinities, the one with a Brazilian, the other with a Mad-
agascar gronp; while the only peenliar genera belong to the
Rhynoophora, but are allied to European forms. These last al-
most certainly form a portion of the more ancient fauna of the
islands which migrated to them in proglacial times, while the
Brazilian elater appears to be the solitary example of a living
insect brought by the Gnif Stream to these remote shores. The
elater, having its nearest living ally in Madagascar {J^la^trua
(lologtis), cannot be held to indicate any independent communi-
cition between these distant islands; but is more probably a
Chap.XIL] the AZORES. 243
relic of a once more wide-spread type which has only been able
to maintain itself in these localities. Mr. Crotch states that
there are some species of beetles common to Madagascar and
the Canary Islands, while there are several genera common to
Madagascar and South America, and some to Madagascar and
Australia. The clew to these apparent anomalies is found in
other geneiti being common to Madagascar, Africa, and South
America, while others are Asiatic or Australian. Madagascar,
in fact, has insect relations with every part of the globe, and
the only rational explanation of such facts is that they are in-
dications of very ancient and wide-spread groups, maintaining
themselves only in a few widely separated portions of what was
at one time or another the area of their distribution.
Land Shelh of the Azores. — Like the insects and birds, the
land shells of these islands have a generally European aspect,
but with a larger proportion of peculiar species. This was to
be expected, because the means by which mollusks are carried
over the sea are far less numerous and varied than in the case of
insects;* and we may therefore conclude that their introduction
is a very rare event, and that a species once arrived remains for
long periods undisturbed by new arrivals, and is therefore more
likely to become modified by the new conditions, and then fixed
as a distinct type. Out of the sixty-nine known species, thirty-
seven are connnon to Europe or the other Atlantic islands; while
thirty-two are peculiar, though almost all are distinctly allied to
European types. The majority of these shells, especially the
peculiar forms, are very small, and many of them may date back
to beyond the glacial epoch. The eggs of these would be ex-
ceedingly minute, and might occasionally be carried on leaves
or other materials during gales of exceptional violence and dura-
tion, while others might be conveyed with the earth that often
sticks to the feet of birds. There are also, probably, other un-
known means of conveyance; but, however this may be, the
ffcneral character of the land mollusks is such as to confirm the
conclusions we have arrived at from a study of the birds and
insects — that these islands have never been connected with a
* See Chap. V., p. 74.
244
ISLAND LrPK.
[Part II.
continent, and have been peopled with living things by such
forms only as in some way or other have been able to reacli
them across many hundred miles of ocean.
The Flora of the Azores. — The flowering plants of the Aaores
have been gtiidied by one of our first botanists, Mr, H. C.Wat-
eon, who lias himself vigited the islands and made extensive col-
lections; and he lias given a complete catalogue of the species
in Mr. Godmaii's volume. As our object iu the present work is
to trace the past history of the mora important islands by means
of the forms of life that inhabit them, and as for this purpose
plants are sometimes of more vulne than any class of animals,
it will be well to take advantage of the valuable materials here
available in order to ascertain how far the evidence derived from
the two organic kingdoms agrees in character; and also to ob-
tain some general results which may be of service in onr dis-
cussion of more difficult and more complex problems.
There are in the Azores 480 known species of flowering plants
and ferns, of which no less than 440 are found also in Europe,
Madeira, or the Canary Islands ; while forty are peculiar to the
Azores, but are more or less closely allied to European species.
As botanists are no less prone than zoologists to invoke former
land-connections and continental extensions to account for the
wide dispersal of objects of their stndy, it will be well to ex-
amine somewhat closely what these facts really imply.
The Di«peraai of Seeds. — The seeds of plants are liable to bo
dispersed by a greater variety of agents than any other organ-
isms, while their tenacity of life, under varying conditions of
heat and cold, drought and moisture, is also exceptionally great.
They have also an advantage, in that the great majority of flovr-
ering plants Iiave the sexes united in the same individual, so
that a single seed in a state fit to germinate may easily stock a
whole island. The dispersal of seeds has been studied by Sir
Joseph Hooker, Mr. Darwin, and many other writers, who have
made it suflieicntly clear that they are in many cases liable to be
carried enormous distances. An immense number are specially
adapted to bo carried by the wind, through the possession of
down or hairs or memhrimoiis wings or processes; while otliere
are so minute, and produced in such profusion, that it is difficult
Chap. XII.] THE AZORES. 245
to place a limit to the distance thej might be carried by gales
of wind or hurricanes. Another class of somewhat heavier
seeds or dry fruits are capable of being exposed for a long time
to sea-water without injury. Mr. Darwin made many experi-
ments on this point, and he found that many seeds, especially
of atriplex, beta, oats, capsicum, and the potato, grew after one
hundred days' iinmei*8ion, while a large number survived fifty
days. But he also found that most of them sink after a few
daj's' immersion, and this would certainly prevent them being
floated to very great distances. It is very possible, however,
that dried branches or flower-heads containing seeds would float
longer, while it is quite certain that many tropical seeds do float
for enormous distances, as witness the double cocoa-nuts which
cross the Indian Ocean from the Seychelle Islands to the coast
of Sumatra, and the West Indian beans which frequently reach
the west coast of Scotland. There is therefore ample evidence
of the possibility of seeds being conveyed across the sea for great
distances by winds and surface currents.*
Birds as Seed-carriers. — The great variety of fruits that are
eaten by birds afford a means of plant-dispersal in tlie fact that
seeds often pass through the bodies of birds in a state well fitted
for germination; and such seeds may occasionally be carried
long distances by this means. Of the twenty-two land birds
* Some of Mr. Darwin's experiments nre very interesting and suggestive. Ilii>e
hazel-nuts sank immediately, but when dried they floated for ninety days, and after-
wards germinated. An asparagus-plant with ripo berries, w lien dried, floated for
eighty-five days, and the seeds afterwards germinated. Out of ninety-four dried
plants experimented with, ciglitecn floated for more than a month, and some for
three months, and their powers of germination seem never to have been wholly de-
stroyed. Now, as oceanic currents vary from thirty to sixty miles a day, snch plants
under the most favorable conditions might be carried 90 X GO — 5400 miles ! But even
lialf of this is ample to enable them to reach any oceanic island, and we must remem-
ber that till completely water-logged they might be driven along at n much gi-eater rate
by the wind. Mr. Danvin calculates the distance by the average time of flotation to
lie *J24 miles; but in such a case as this we are entitled to take the extreme cases,
because such coinitless thousands of plants and seeds must be carried out to sea an-
nually that the extreme cases in a single experiment with only ninety-four plants
must hn])pen hundreds or thousands of times, and with hundreds or thousands of spe-
cies, naturally, and thus aflurd ample opportunities for successful migration. (See
** Origin of Species," Gth ed., p. 325.)
ISLAND lATO.
IPamt 11.
fonnd ill the Azores, balf arc more or less frnit-eaters, and these
may have been the means of introducing some plants into the
islande.
Birds also frequently have small portions of earth on their
feet J and Mr. Darwin has shown by actual experiment that al-
moet all such earth contains seeds. Thus, in nine grains of earth
on the leg of a woodcock a seed of the toad-riish was found
which germinated; while n wounded red-logged partridge had
A ball of earth weighing six and a half ounces adhering to its
leg. and from this earth Mr. Darwin raised no less than eighty-
two separate plants of about five distinct species. Still mora
remarkable was the experiment wilh six and three -qnarter
ounces of nmd from the edge of a little pond, which, carefully
treated under glass, produced 537 distinct plahts! This is
equal to a seed for every six grains of mud ; and when we
consider how many birds freqnent tlio edges of ponds in search
of food, or come thcro to drink, it is evident that great num-
bers of seeds may be dispersed Ity this means-
Many seeds have hispid awns, hooks, or prickles which readily
attach them to the feathers of bii-ds, and a great number of
aquatic birds nest inland on the ground; and as these- are pre-
eminently wanderers, they ranst often aid in the dispersal of
such plants.'
' Tlio fuUowiiig rcmarbK, kindly communicnlcd lo me by Mr. II. N. Moseley,
nnlum11«i lo ilia CAnlltaijrr, titrou miicli light on the ngency uf birils in itie dinribu-
tlonof|i1aiiu; "OiiwI>nch("Veg, JerEiile,"VuLII., p.41Hi)lnrsinucliilres»onllie
niile rnnging of ilio ntlMiiroai (nioniaticii) ucnm* iho eqiulor from Cupe Horn to the
Karile IeIhiiiI*, and tliinki tlini the prcMnce of ttie aaina ptnnls in Krclic nnJ niUDrctic
I'exions mny be accounted for, ]>0KEib1y, by this fuel. I wui tniich struck nt .Mniion
lalnnd, of liia Pilnco I^n'ird eroiip, by observing ihnl liio grcnt nlbiitrosa breeds in
the miJit of It ilenie, law hevbnKe, nnd constriictj it* nett of n monnd of Inrf niid
herbage. Some of the indigenous plnnts, e. g. Arivnn, hnvo flowor-liainis ivliicli slirlt
like bniTs lo fentticni, elo., and scctn epecinlly adnjiled for imn9|<onnlion by birdn.
Beaides the nlbntrosMs, vnriotu ipecies of Fiiwclbtria and Pufflnus, birds wliicli mnga
ov«r injQiange distnncei, mny, I iliink, hare played a B>wt port in Iho disiribution of
planM, and opecinlij nccount, in some menaure, far the oiheniisQ difficult fuct (nlien
occurring in tlie tropica) ihnt nidely dislnnt iilnndi linrs sirailnr monntain pinnti.
Tlie I'mcellnriii* nnd Paffinni, in neiting, bamnv in ihe emiiiiJ. as fur ni 1 have
•e«n cliooting often places irhcro llic rcgetnliun is llie lliickesL Tlio birds in bur-
ruwinf; gel llicir fenibci! corered uiiti vesciiible motihl, wliidi must incbido sporo)
nnd vttail scuJi. In bigli Intitiidrs llio binU uftcn b.irroiT near ilic ■e.vlevcl, ns at
Chap. XII.] THE AZORES. 247
Facilities for Dispersal of Azorean Plants, — Now, in the
course of very long periods of time, the various causes here
enumerated would be sufficient to stock the remotest islands
with vegetation, and a considerable part of the Azorean flora
appears well adapted to be so conveyed. Of the 439 flowering
plants in Mr. Watson's list, I find that about 45 belong to genera
that have either pappus or winged seeds ; 65 to such as have
very minute seeds; 30 have fleshy fruits such as are greedily
eaten by birds ; several have hispid seeds; and 84 are glumaceous
plants, which are all probably well adapted for being carried partly
by winds and partly by currents, as well as by some of the other
causes mentioned. On the other hand, we have a very suggestive
fact in the absence from the Azores of most of the trees and
shrubs with large and heavy fruits, however common they may
be in Europe. Such are oaks, chestnuts, hazels, apples, beeches,
aldei-s, and firs; while the only trees or large shrubs are the
Portugal laurel, myrtle, laurestinus, elder, Laurus Canariensis,
MyricaFaya, and a doubtfully peculiar juniper — all small berry-
bearers, and therefore likely to have been conveyed by one or
other of the modes suggested above.
There can be little doubt that the truly indigenous flora
of the islands is far more scanty than the number of plants
recorded would imply, because a large but unknown propor-
tion of the species are certainly importations, voluntary or in-
voluntary, by man. As, however, the general character of the
whole flora is that of the southwestern peninsula of Europe,
and as most of the introduced plants have come from the
Tristan d'Acunha or Kerguelcn Land ; but in the tropics they choose the mountains
for their nestiug-phice (Finsch and Ilarthiub, "Ornith. der Viti- und Tonga-Inseln,**
18G7, Einlcitung, p. xviii.). Thus, Puffinus Megasi nests at the top of the Korobasa
basnga mountain, Viti Levu, fifty miles from tlio sea. A Procellaria breeds in like
manner in the high mountains of Jamaica, I believe at 7000 feet. Peale describes
the same habit of Procellana rostrata at Tahiti, and I saw the burrows myself
amidst a dense growth of fern, etc., at 4400 feet deration in that island. Phaethon
has a similar habit. It nests at the crater of Kilauea, Hawaii, at 4000 feet elevation,
and also high up in Tahiti. In order to account for the transportation of the plants,
it is not, ot course, necessary that the same species of Procellaria or Diomedea should
now range between the distant points where the plants occur. The ancestor of the
now ditlei ing sjiecies might have carried the seeds. The range of the genns is suf-
ficient."
848
ISLAND LIFE.
tPABTH.
eume coiintrj', it ia alinost iiiipoeeible now to eepiirate tliem,
and Mr. Wateon lias not attempted to do so. Tlie whole flora
contains representatives of 80 natural orders and 250 genera;
and even if we euppose that one half the species only aro truly
indigenous, tliere will still remain a wonderfully rich and varied
flora to have been carried, by the various natural means above
indicated, over 900 milea of ocean, more especially as the
large proportion of species identical with those of Europe
shows that their introduction lins been comparatively recent,
and that it is probably (as in the case of the birds) still going
on. We may therefore feel eure that we have liere by no nioana
reached the limit of distance to which plants can bo conveyed
by natural means across the ocean ; and tins concUieion will be
of great value to us in inveatignting other cases wlicre the evi-
dence at our command is less complete and the iudifations of
origin more obscnre or conflicting.
Of the forty species which nre considered to be peculiar to
the islands, all are allied to European plants except six, whoso
nearest affinities are in the Canaries or Madeira, Two of the
Oonipositfe are considered to be distinct genera, but in this or-
der generic divisions rest on slight technical distinctions; and
the t'ampantda VidtUii is veiy distinct from any otJier known
species. With these exceptions, most of the peculiar Azorean
species nre closely allied to European plants, and are in several
cases little more than varieties of them. While, therefore, we may
believe that the larger part of the existing flora reached the isl-
ands since the glacial epoch, a portion of it may be more ancient,
as there is no doubt that a majority of the species could withstand
Eome lowering of temperature; while in such a warm latitude,
and surrounded with sea, tliere would always be many sunny
iind sheltered spots in which even tender plants might flourish.
Jiii-porinnt Deduction from the Ptfculiaril'ws of the Asorean
J^auiui and Flora.— TXiato is one conclusion to be drawn from
the almost wholly European character of the Azorean fauna and
flora which deserves special attention — namely, that the peopling
of remote islands is not duo so ranch to ordinary or normal as
to extraordinary and exceptional causes. These islands lie in
tho coui-se of the southwesterly return trades and also of tlte
Chap. XIL] BERMUDA. 249
Gulf Stream, and we should tlrcrefore naturally expect that
American birds, insects, and plants would preponderate if thej
were conveyed by the regular winds and currents, which are
both such as to prevent European species from reaching them.
But the violent storms to which the Azores are liable blow from
all points of the compass ; and it is evidently to these, combined
with the greater proximity and more favorable situation of the
coasts of Europe and North Africa, that the presence of a fauna
and flora so decidedly European is to be traced.
The other North Atlantic islands — Madeira, the Canaries, and
the Cape Verds — present analogous phenomena to those of the
Azores, but with some peculiarities dependent on their more
southern position, their richer vegetation, and, perhaps, their
greater antiquity. These have been sufficiently discussed in my
" Geographical Distribution of Animals" (Vol. I., pp. 208-215);
and as we are now dealing with what may be termed typical ex-
amples of oceanic islands, for the purpose of illustrating the
laws and solving the problems presented by the dispersal of
animals, we will pass on to other cases which have been less fully
discussed in that work.
BERMUDA.
The Bermudas are a small group of low islands formed of
coral and blown coral-sand consolidated into rock. They are
situated in 32° N. lat., about seven hundred miles from North
. Carolina, and somewhat farther from the Bahama Islands, and are
thus rather more favorably placed for receiving immigrants from
America and its islands than the Azores are with respect to Eu-
rope. There are about one hundred islands and islets in all, but
their total area does not exceed fifty square miles. They are
surrounded by reefs, some at a distance of thirty miles from the
main group ; and the discovery of a layer of earth with remains
of cedar trees forty-eight feet below the present high-water mark
shows tliat the islands have once been more extensive, and prob-
ably included the whole area now occupied by shoals and reefs.'
* Nature, Vol. VI., p. 262; "Kecent Observations in the Bermudas," bjr Mr. J.
Matthew Jones.
250
ISLAND LIFE.
[Pabt H.
Immediately beyond these reefs, however, entends a very deep
ocean, while about four lumdreJ and fifty miles diatfliit in u
Boiitheftst direction the deepest part of the North Atlantic is
reached, where Bouiidiiigs of 3S25 and 3S75 fathoms have been
obtained. It is clear, therefore, that these islands nre tvpieally
IE.— The light lint indirulet
'I'lia (Inrk tint "
Tlio flcurcB allow tlia dcplli i
fnthom*.
Soundings were taken by tlic VhnUfngur in fonr different di-
rections around Bcrmnda, and always showed a rapid deepening
of the aea to about 2500 fathoms. This was bo remarkjiblo
that, in his rcjwrts ti> tlio Admiralty, Captain Narcs epoko of
Chap. XII.]
BERMUDA.
251
Bermuda as " a solitary peak rising abruptly from a base only
120 miles in diameter," and in another place as "an isolated
peak rising abruptly from a very small base." These expres-
sions sliow that Bermuda is looked upon as a typical exam-
ple of an " oceanic peak ;" and on examining the series of offi-
cial reports of the Challenger soundings, I can find no similar
case, although some coasts, both of continents and islands, de-
scend more abruptly. In order to show, therefore, what is the
real character of this peak, I have drawn a section of it on a true
scale from the soundings taken in a north and south direction
N
BERMUDA
8
-5S MILES-
->^I8 MILCt-:>^
■46 MILES.
SECTION OF BERMUDA Ain> ADJACENT SEA-BOTTOM.
The figures sIiow the depth in fathoms nt fifty-fire miles north nnd furty-six miles
south of the islands respectively.
where the descent is steepest. It will be seen that the slope is
on both sides very easy, being 1 in IC on the soutli, and 1 in
19 on the north. The portion nearest the islands will slope
more rapidly, perhaps reaching in places 1 in 10 ; but even this
is not steeper than many country roads in hilly countries, while
the remainder would be a hardly perceptible slope. Although
generally very low, some parts of these islands rise to 250
feet above the sea-level, consisting of various kinds of lime-
stone rock, sometimes soft and friable, but often very hard and
even crystalline. It consists of beds which sometimes dip as
much as 30°, aild exhibit, besides, great contortions, so that at
first sight the islands appear to exhibit on a small scale the phe-
nomena of a disturbed Palaeozoic district. It has, however, long
been known that these rocks are all due to the wind, which
blows up the fine calcareous sand, the product of the disintegra-
tion of coral, shells, serpulae, and other organisms, forming sand-
hills forty and fifty feet high, which move gradually along, over-
whelming the lower tracts of land behind them. These are con-
solidated by the percolation of rain-water which dissolves some
ISLAIID LIFE.
[PaetIL
of the lime from the more porous tracts aiid deposits it lower
down, filling every fissure with stalagmite.
The lied Clay of Bifmiuda. — Besides the calcareous rocks,
there is found in many parts of tiie islands a layer of red earth
or clay, containing about thirty per cent, of oxide of iron. This
very closely resembles, both in color and chemical composition,
the red clay of the ocean-floor, found widely spread in the At-
lantic at depths of from SiSOO to 3150 fathoms, and occurring
abundantly all ronnil Bermuda. It appears, therefore, at first
Bight, as if the ocean-bed itself Ii,ie been Iiere raised to the sur-
face, and a portion of its covering of red clay preserved ; and
this is the view adopted by Mr. Jones in his paper ou the " Bot-
any of Bermuda." lie sitys, after giving the analysis, ''Tiiia
analysis tends to convince us that the deep ehocolate-colored
red clay of the islands found in the lower levels, and from high-
water mnrk some distance into the sea, originally came from the
ocean-floor ; and that when by volcanic agency the Bermuda col-
umn was raised from the depths of the sen, its summit, most
probably broken in outline, appeared above the surface covered
with this red mud, which in the course of ages has but slightly
changed its composition, and yet possesses suflicient evidence to
prove its identity with that now lying contiguous to the base of
the Bermuda column." But in his "Guide to Bermuda" Mr.
Jones tells us that this same red earth lias been found, two feet
thick, under coral rock, at a depth of forty-two feet below low-
wnter uiai'k, and that it "rested on a bed of compact oalcareons
sandstone." Now it is quite certain that this "calcareous sand-
stone" was never formed at the bottom of the deep ocean TOO
miles from land; and the oeenrrence of the red earth at differ-
ent levels upon coralline sand rock is therefore more probably
due to some process of dccompositiou of the rotk itself, or of
the minute organisms which abound in the blown sand. The
fortlieoming volumes on the results of the ChaUengifp expedition
will probably clear up the difficulty.
Zotiogy of Bermuda. — As might be expected from their ex-
treme isolation, these islands possess no indigenous land mam-
malia, frogs, or snakes. There is. liowcver, one lizard, which
Professor Cope considers to be distinct from any American spe-
Chap. XII. ] BERMUDA. 253
cies, and which he has named Plestiodon longirostris. It is said
to be most nearly allied to P. fasciatus of the Southeastern
States, from which it differs in having nearly ten more rows of
scales, the tail thicker, and the muzzle longer. In color it is ashy
brown above, greenish blue beneath, with a white line black-
margined on the sides, and it seems to be tolerably abundant in
the islands. This lizard is especially interesting as the only ver-
tebrate animal which exhibits any peculiarity.
Birds. — Notwithstanding its small size, low altitude, and re-
mote position, a great number of birds visit Bermuda annually,
some in large numbers, others only as accidental stragglers. Al-
together, over a hundred and eighty species have been recorded,
rather more than half being wading and swimming birds, whose
presence is not so much to be wondered at, as they are great
wanderers; while about eighty-iive are land birds, many of
which would hardly be supposed capable of flying so great a
distance. Of the hundred and eighty species, however, about
thirty have only been seen once, and a great many more are
very rare ; but about twenty species of land birds are recorded
as tolerably frequent visitors, and nearly half these appear to
come every year.
There are only ten species which are permanent residents on
the island — eight land and two water birds — and of these one has
been almost certainly introduced. These resident birds are as
follows :
1. Gaieosroptes CaroHnensis. (The Catbird.) Migrates nloiig the east coast of
the United States.
2. Si alia si a f is. (The Bhiebird.) Migrates along the east coast.
3. Vireo Novirboracensis, (Tiie White-eyed Green Tit.) Migrates along the east
coast.
4. Passer domesturus. (The English Sparrow.) ? Introduced.
5. Corvus Atnericanus. (The American Crow.) Common over all North Amer-
ica.
G. Cardinalis Virgifdanus, (The Cardinal-bird. ) Migrates from Carolina south-
ward.
7. ChatfKppeiia passerina, (The Ground-dove.) Louisiana, West Indies, and
Mexico.
8. Orfi/x Virginianus. (The American Quail.) New England to Florida.
0. Ardea herodias. (The Great Blue Heron.) All North America.
10. Fulir.a Americana, (The American Coot.) Temperate and tropical North
America.
S54
ISLAND LtFK.
[I'abt II.
It will be seen that those arc all very cQiiimon North Ameri-
can birds, and most of them are constant visitors from the inaiii-
Iiiiid, so thiit, liowever long they may linve inhabited the islands,
there has been no chance for them to have acquired nny distinc-
tive chamctere through isolation.
Among the most regular visitants which are not resident are
the common North American kingfisher (Ctryle alcifon), the
wood-WHgtail {Siurus JVov^oracetisi-s), tlie wido-rauging rice-
bird {Voliclionyx ori/sivora), and a moor-hen [OaUlitu/u galea-
hi); the first three being very common over almost all North
America, and the last abundant in the Boiithcrn portion of it.
Com^rlaoii of the Bird Faunm of Bvrm'tda and the Azores.
— The bird fauna of Bermud.i tiius diffcra from that of the
Azores in the much smaller number of resident epecies and the
presence of several regular migrants. This is due, first, to the
small area and little-varied surfnce of these islands, as weJl as to
their limited flora and small supply of insects not affording con-
ditions suitable for the residence of many species all the year
round ; and, secondly, to the peculiarity of the climate of North
America, which causes a much Iarj;er number of its birds to be
migratory than in Europe. The Northern United States and
Canada, with a sunuy climate, luxuriant vegetation, and abun-
dant insect life during tlie summer, snpply food and shelter to nn
immense number of insectivorous and frugivorous birds; so that
during the breeding season Canada is actually richer in bird life
than Florida. But as the severe winter comes on, all these are
obliged to migrate southward — some to Carolina, Georgia, and
Florida, otliora as far as the West Indies, Mosico, or even to
Guatemala and South AmeriiM.
Every spring and autumn, therefore, a vast multilnde of birds,
belonging to more than a hundred distinct species, migrate
northward or southward in Eastern America. A large piftpor-
tion of tlicsc pass along the Atlantic const; and it has been ob-
served that many of them fly some distance out to sea, passing
straigiit across bays from headland to headland by tlic shortest
route.
Now. as the time of these migrations is the season of storms,
especially the autumnal one, which nearly coincides with the
Chap. XII.J BERMUDA. 255
liurricanes of the West Indies and the northerly gales of the
coast of America, the migrating birds are very liable to be car-
ried out to sea. Sometimes they may, as Mr. Jones suggests, be
carried up by local whirlwinds to a great height, where, meeting
with a westerly or northwesterly gale, they are rapidly driven
seaward. The great majority, no doubt, perish, but some reach
the Bermudas and form one of their most striking autumnal feat-
ures. In October, Mr. Jones tells us, the sportsman enjoys more
shooting than at any otlier time. The violent revolving gales,
which occur almost weekly, bring numbers of birds of many
species from the American continent, the different members of
the duck tribe forming no inconsiderable portion of the whole;
while the Canada goose and even the ponderous American
swan have been seen amidst the migratory host. With these
come also such delicate birds as the American robin {Turdua
inigr atari U8\ the yellow-rumped warbler {Dendrceca caroncUa)^
the pine-warbler {Detidrceca pinus), the wood-wagtail {Siurus
Nov(jeborac€n8is\ the summer redbird {Pyranga cestiva\ the
snow-bunting {Plectrophanes nivalis)^ the redpoll {^giothus
linarius\ the king-bird {Tyrannies Carolinenais)^ and many oth-
ers. It is, no doubt, in consequence of this repeated immigration
that none of the Bermuda birds have acquired any special pecu-
liarity constituting even a distinct variety; for the few species
that are resident and breed in the islands are continually crossed
by individual immigrants of the same species from the mainland.
Four European birds also have occurred in Bermuda — the
wheat-ear {Saxicola cenanthe\ which visits Iceland and Lapland
and sometimes the Northern United States; the skylark {Alavr
(la arvensis\ but this was probably an imported bird or an es-
cape from some ship; the land-rail {Crex praten8is\ which also
wanders to Greenland and the United States ; and the common
snipe {Scolopax gaUinago\ which occure not unfrequently in
Greenland, but has not yet been noticed in North America. It
is, however, so like the American snipe {S. WUsoni) that a strag-
gler might easily be overlooked.
Two small bats of North American species also occasionally
reach the island, and these are the only wild mammalia except
rats and mice.
256 ISLAND LIFE. [Pabt IF.
Insects of Bermuda, — Insects appear to be veiy scarce ; but
it is evident from the lists given by Mr. Jones that only the
more conspicuous species have been yet collected. These com-
prise nineteen beetles, eleven bees and wasps, twenty-six butter-
flies and moths, nine flies, and the same number of Hemiptera,
Orthoptera, and Neuroptera respectively. All appear to be com-
mon North American or West Indian species ; but until some
competent entomological collector visits the islands it is impos-
sible to say whether there are or are not any peculiar species.
Land Mollusca. — The land shells of the Bermudas are some-
what more interesting, as they appear to be the only group of
animals except reptiles in which there are any peculiar species.
The following list has been kindly furnished me by Mr. Thomas
Bland, of New York, who has made a special study of the ter-
restrial molhisks of the West Indian Islands. The species which
are peculiar to the islands are indicated by italics :
L18T OF THE Land Shells of Bebmcda.
1. Succinea fulgens. (Ijea.) Also in Cuba.
2. ** Bermudensis. (Pfeiffer.).. ** Bnrbndoes?
8. " Margarita. (Pfr.) *' Hayti.
4. Hyalina Bermudensis, (Pfr.) A peculiar form which, according to Mr.
Binney, ** cannot be placed in any recog-
nized genns." A larger sub-fossil variety
also occurs, named H. Nelsoni by Mr.
Bland, and which appears sufficiently
distinct to be classed as another species.
/i. ** cii'cunifii'mata. (Red field.)
6. *' discrepans. (l*fr.)
7. Patula Reiniana. (Pfr.)
8. ** hypolepta. (Shuttleworlh.). .Probably the same as P. luinuscula (Bin-
ney), a wide-spread American species.
9. lleli.x vortex. (Pfr.) Southern Florida and West Indies.
10. ** niicrodonta. (Desh.) Bahama Islands.
11. ** appressa. (Ssiy.) Virginia and adjacent States : perhaps in-
troduced into Beimuda.
12. ** pulchella. (Miill.) Europe; very close to If. minuta (Say) of
the United States. Introduced into Ber-
muda?
13. ** ventricosa. (l)rap.) Azores, Canary Islands, and South Europe.
14. Bulimulus nitidulus. (Pfr.) Cuba, Hayti, etc.
15. Stenogyra octona. (Ch.) West Indies and South America.
IG. Cionclla acicula. (Miill.) Florida, New Jersey, and Europe.
Chap. XII.] BERMUDA. 257
1 7. Pupa pelliicidn. (l*fi*.) West Indies, generallr.
18. '* Barbndensis. (Ffr.) Bnrbndoes?
19. '* Jamaicensis. (C.B. Ad.). Jamaica.
20. Ilelicina convexa. (Pfr.) Barbuda.
Mr. Bland indicates only four species as certainly peculiar to
Bermuda, and another sub-fossil species ; while one or two of the
remainder are indicated as doubtfully identical with those of
other countries. We have thus at least one fourth of the land
shells peculiar, while almost all the other productions of the isl-
ands are identical with those of the adjacent continent and isl-
ands. This corresponds, however, with what occurs generally
in islands at some distance from continents. In the Azores only
one land bird is peculiar out of eighteen resident species; the
beetles show about one eighth of the probably non-introduced
species as peculiar, the plants about one twentieth ; while the
land shells have about half the species peculiar. This difference
is well explained by the much greater difficulty of transmission
over wide seas, in the case of land shells, than of any other ter-
restrial organisms. It thus happens that when a species has
once been conveyed it may remain isolated for unknown ages,
and has time to become modified by local conditions unchecked
by the introduction of other specimens of the original type.
Flora of Bermuda. — Unfortunately, no good account of the
plants of these islands has yet been published. Mr. Jones, in
his paper " On the Vegetation of the Bermudas," gives a list of
no less than 480 species of flowering plants; but this number
includes all the culinary plants, fruit-trees, and garden flowers,
as well as all the ornamental trees and shrubs from various
parts of the world which have been introduced, mixed up with
the European and American weeds that have come with ag-
ricultural or garden seeds, and the really indigenous plants, in
one undistinguished series. It appears, too, that the late gov-
ernor, Major-general Lefroy, " has sown and distributed through-
out the islands packets of seeds from Kew, representing no less
than 600 species, principally of trees and shrubs suited to sandy
coast soils'' — so that it will be more than ever difficult in fut-
ure ycai*s to distinguish the indigenous from the introduced
vegetation.
17
18LANU J-lFli.
tPAHT li.
From tlio researches of Dr. Eeiii and Mr. Moseley there ap-
pear to lje about two hundred and fifty flowering plants in a, wild
state, and of tboBe Mr. Moscley thinks less than half are indig-
enous. The majority are tropical and West Indian, while oth-
ers are common to tiie isouthecn States of North America ; the
former class having been largely brought by means of the Gulf
Stream, the latter by the agency of birds or by winds. Mr.
Jones tells ua that the currents bring numberless objects ani-
mate and inanimate from the'Caribbean Sea, including the seeds
of trees, shrubs, and other plants, wiiich arc continually cast
ashore and Bometimcs vegetate. The soapberry-tree {Sapindus i
saponaria) has been actually observed to originate in this way.
Professor Oliver informs me that ho knows of no undoubtedly
distinct 8])ecie8 of flowering plants peculiar to Bermuda, though
there are some local forms of continental species^instancing
Siayvinchium.jBerjn'udlanum, and Rhus toxicodendron. Tliere
arcjhowever, two ferns — an AdiantumandaNephrodinm— which
are unknown from any other locality, and this rendere it prob-
able that some of the flowering plants are also peculiar. The
juniper, which is so conspicuous a feature of the islands, is said
to be a West Indian species (Junijwug Jiarhadeneis) found in
Jamaica and the Bahamas, not the North American red cedar;
but there seems to be still some doubt about this common plant.
Mr. Moseloy, who visited Bermuda in tlie ChaUengev, has well
explained the probable origin of the vegetation. The large
number of West Indian plants is, no doubt, due to the Gulf
Stream and constant surface drift of warm water in this direc-
tion, while others have been brought by the annual cyclones
which sweep over the intervening ocean.- The great number of
American migratory birds, including large flocks of the Ameri-
can golden plover, Mith ducks and other aquatic species, no doubt
occasionally bring seeds, either in the mud attached to their feet
or in their stomachs.' As these causes are either constantly in
action or recur annually, it is not surprifiing that almost all the
species should be unchanged owing to the frei^nent intercroeaing
" Ni'ies oil ilio Vegclniion of Bermiidn," !■? II. N. Mo»ele», Journal 0/ the Lin-
% A'oclXy.Vol. XIV., Botanv, p. 317.
Chap. XII. J BERMUDA. 259
of freshly arrived specimens. If a competent botanist were
thoroughly to explore Bermuda, eliminate the species introduced
by human agency, and investigate the source from whence the
others were derived and the mode by which they had reached
so remote an island, we should obtain important information as
to the dispersal of plants, which might afford us a clew to the
solution of many ditficult problems in their geographical distri-
bution.
Concluding Remarks, — The two groups of islands we have
now been considering furnish us with some most instructive
facts as to the power of many groups of organisms to pass over
from seven hundred to nine hundred miles of open sea. There
is no doubt whatever that all the indigenous species have thus
reached these islands, and in many cases the process may be seen
going on from year to year. We find that, as regards birds, mi-
gratory habits and the liability to be caught by violent storms
are the conditions which determine the island population. In
both islands the land birds are almost exclusively migrants ; and
in both the non-migratory groups — wrens, tits, creepers, and
nuthatches — are absent ; while the number of annual visitors is
greater in proportion as the migratory habits and prevalence of
storms afford more cfiicient means for their introduction.
We find also that these great distances do not prevent the
immigration of some insects of most of the orders, and espe-
cially of a considerable number and variety of beetles ; while
even land shells are fairly represented in both islands, the large
proportion of peculiar species clearly indicating that, as we might
expect, individuals of this group of organisms arrive only at
long and irregular intervals.
Plants are represented by a considerable variety of orders and
genera, most of which show some special adaptation for dispersal
by wind or water, or through the medium of birds ; and there is
no reason to doubt that, besides the species that have actually
established themselves, many others must have reached the isl-
ands, but were not suited to the climate and other physical con-
ditions, or did not find the insects necessary to their fertiliza-
tion.
If, now, we consider the extreme remoteness and isolation of
260 ISLAND LIFE. [Past IL
these islands, their small area, and comparatively recent origin,
and that, notwithstanding all these disadvantages, they have ac-
quired a very considerable and varied flora and fauna, we shall,
I think, be convinced that, with a larger area and greater an-
tiquity, mere separation from a continent by many hundred
miles of sea would not prevent a country from acquiring a very
luxuriant and varied flora, and a fauna also rich and peculiar
as regards all classes except terrestrial mammals, amphibia, and
some groups of reptiles. This conclusion will be of great im-
portance in many cases where the evidence as to the exact ori-
gin of the fauna and flora of an island is less clear and satis-
factory than in the case of the Azores and Bermuda.
CiiAP.XIlI.] THE GALAPAGOS ISLANDS. 261
CHAPTER XIII.
THE GALAPAGOS ISLANDS.
Position and Physical Features. — Absence cf Indigenous Mammalia and Amphibia.
— Reptiles. — Birds. — Insects and Land Shells. — ^The Keeling Islands as Illustrat-
ing the Manner in which Oceanic Islands are Peopled. — Flora of the Galapagos.
— Origin of the Flora of the Galapagos. — Concluding Hemarks.
The Galapagos differ in many important respects from the
islands we liave examined in our last chapter, and tbe differ-
ences are such as to hare affected tlie whole chamcter of their
animal inhabitants. Like the Azores, they are volcanic, but they
are much more extensive, the islands being both larger and more
numerous; while volcanic action has been so recent and exten-
sive that a large portion of their surface consists of barren lava-
fields. They are considerably less distant from a continent than
either the Azores or Bermuda, being about six hundred miles
from the west coast of South America and a little more than
seven hundred from Veragua, with the small Cocos Islands in-
tervening; and they are situated on the equator instead of being
in the north temperate zone. They stand upon a deeply sub-
merged bank, the lOOOfathom line encircling all the more im-
portant islands at a few miles' distance, whence there appears to
be a comparatively steep descent all round to the average depth
of that portion of the Pacific, between 2000 and 3000 fathoms.
The whole group occupies a space of about three hundred by
two hundred miles. It consists of five largo and twelve small
islands ; the largest (Albemarle Island) being about eighty miles
long and of very irregular shape, while the four next in impor-
tance— Chatham, Indefatigable, James, and Narborough Islands
— are each about twenty-five or thirty miles long, and of a
rounded or elongate form. The whole are entirely volcanic,
and in the western islands there are numerous active volcanoes.
ISLAND LIFE.
[lU.
Unlike the otliei" groups of islands we Lave been conBidcriiig;,
these are situated iu a comparatively calni sea, ^heie storms are
of i-are occurrence and even strong winds almost unknown.
Tliej are traversed by ocean ctirrenla which are strong and con-
stant, flowing towai-da the northwest from the coast of Pern J
and these physical conditions have had a powerful inflnence oikl
the animal and vogotable forms by which tlio islands arc novl
inhabited. The Galapngos have also, during three centnne8,4
been frequently visited by EiiropeanB, and were long a favoi
^ L-B*!-. XIII.] THE GALAPAGOS ISLANDB. 26S ^M
^M reeort of buccaneers an<l traders, wlio found an ample sapiAy
^H food in the large tortoises whidi abound there; and to tlie
^1 vieiu WD may peiliapa trace the introdnction of some anima
^H whose presence it is otherwise difflcult to account for. The veg
t
e
s
MJ iH • act Ml _
^^^^k <)WC^^^^^^^^^^^^^^^^^^^^H
7^^^^^^^^^^^^^|Hi|^^^^^^^^^^^^Hi
^^^^^^^^^^^^^^r r,<>,aMi:coH :. ^^^^^^^^^^^^M
J^^K f: '^^^^L
^^m/r'-:^^"^^^'' ^1
«»r o. iB« 0.1..-.OO..
^H Tl<« liitht tint ilioug n deplh of leu thxn 1000 ru1hon». ^M
^^H The Ggurei iliow ibe ilciHh in fiHbomi. ^H
^^M tation ie generally ecunty, but etill amply enfficlent for tlie enp- ^|
^1 port of a considei-able ainonnt of animal life, as shown by the H
^^1 cattle, horses, nssee, goats, pigs, doge, and cats n'liieh now niii ^|
^H wild iu some of the islands. H
^^M Absence of Indigeno»ia Mammalia and Amphibia. — As in ail ^H
^H other oceanic islands, we find hero no truly indigenous mam- ^M
264 ISLAND LIFE, [I'jinT U,
malia, for llioiigli tlierc is a inonse of tlie American genus
Ilesperomys, wliicli differs Eomewlint from any known species,
we can ImiiJIy consider tliis to be indigenous; iirat, because tlieso
creatures have been little studied in South America, and there
may yet be many nndescribed species; and, in the second place,
because, even had it been introduced by some European or native
vessel, there is ample time in two or tlii-ee Imndred years for the
very different conditions to liave established a marked diversity
in the charactere of the species. This is the more probable be-
cause there is also a true rat of the Old World genua Mus, which
is said to differ slightly from any known species; and as this
genus is nut a native of the American continents, wo are siii'e
that it mnsl have been recently introduced into tlio Galapagos.
Tlicre can be little doubt, therefore, that the islands are com-
pletely destitute of truly indigenous mammalia; and frogs and
toads, the only tropical representatives of the Amphibia, are
equally unknown.
J^fj)(ileii,-^Rept\\e5, however, which at first sight appear as
nnsnited as mammals to pass over a wide expanse of ocean,
abound in the Galapagos, though the species are not very nu-
merous. TJiey consist of land -tortoises, lizai'ds, and finakee.
The toi'toisea consist of two pecul lar species, Testudo micr&phyes,
found in most of the islands, and T. Ahingdoni, recently dis-
covered on Abingdon Island, na well as one extinct species, T.
ephij^piuin, found on Indefatigable Island. Tiicso are all of
very large size, like the gigantic tortoises of tlie Masearene
Islands, fi'om which, however, tliey differ in structural eliarae-
Icrs; and Dr. Giintlier believes that they have been originally
derived from the American continent.' Considering the well-
known tenacity of life of these animals, and the large number
of allied forms which have aquatic or eubaquatie habits, it is
not a very extravagant supposition that some ancestral form,
carried out to sea by a flood, was oueo or twice safely drifted as
far fls the Galapagos, and thus originated the races which now
inhabit them.
n (lio CoUeciion of ilie Biiiiuli
Chap. XIII.] THE GALAPAGOS ISLANDS. 265
The lizards are five in number — a peculiar species of gecko,
PhyUodaetylxis Galapagerisis^ and four species of the American
family Iguanidse. Two of these are distinct species of the genus
Liocephahis, the other two being large, and so very distinct as to
bo classed in peculiar genera. One of these is aquatic and found
in all the islands, swimming in the sea at some distance from the
shore, and feeding on seaweed ; the other is terrestrial, and is
confined to the four central islands. These were originally de-
scribed by Mr. Bell as Amhlyrhynchua cristatus and A. subana-
taius ; they were afterwards placed in two other genera, Tra-
chycephalns and Oreocephalus (see British Museum Catalogue
of Lizards) ; while in a recent paper by Dr. Giinther the marine
species is again classed as Amblyrhynchus, while the terrestrial
form is placed in another genus, Conolophus.
How these lizards reached the islands we cannot tell. The
fact that they all belong to American genera or families indi-
cates their derivation from that continent, while their being all
distinct species is a proof that their arrival took place at a re-
mote epoch, under conditions perhaps somewhat different from
any which now prevail. It is certain that animals of this order
have some means of crossing the sea not possessed by any other
land vertebrates, since they are found in a considerable number
of islands which possess no mammals nor any other land reptiles;
but Avhat those means are has not yet been positively ascertained.
It is unusual for oceanic islands to possess snakes, and it is
therefore somewhat of an anomaly that two species are found
in the Galapagos. Both are closely allied to South American
forms, and one is hardly different from a Chilian snake, so that
they indicate a more recent origin than in the case of the liz-
ards. Snakes, it is known, can survive a long time at sea, since
a living boa-constrictor once reached the Island of St. Vincent
from the coast of South America, a distance of two hundred
miles by the shortest route. Snakes often frequent trees, and
might thus be conveyed long distances if carried out to sea on
a tree uprooted by a flood such as often occurs in tropical cli-
mates, and especially during earthquakes. To some such acci-
dent we may perhaps attribute the presence of these creatures
in the Galapagos, and that it is a very rare one is indicated by
266 ISLAND LIFE. [Pabt II.
the fact that only two species have as yet succeeded in obtaining
a footing there.
Birds. — We now come to the birds, whose presence here'may
not seem so remarkable, but which yet present features of inter-
est not exceeded by any other group. Fifty-seven species of
birds have now been obtained on these islands, and of these
thirty-eight are peculiar to them. But all the species found else-
where, except one, belong to the aquatic tribes or the waders,
which are pre-eminently wanderers, yet even of these eight are
peculiar. The true land birds are thirty-one in number, and all
but one are entirely confined to the Galapagos ; while more than
half present such peculiarities that they are classed as distinct
genera. All are allied to birds inhabiting tropical America, some
very closely ; while one — the common American rice-bird, which
ranges over the whole northern and part of the southem conti-
nent— is the only land bird identical with those of the main-
land. The following is a list of these land birds taken from Mr.
Salvin's memoir in the Transactions of the Zoological Society
for the year 1876 :
TuKDlD-fi.
.. , / This nnd the two allied species are related
2. melanotus > , ,, • y- ■% w- , • j
3. ** parvulus ) ^
Mniotiltid^.
4. Dendraca aureola Closely allied to the wide - ranging Z>.
a^stiva.
HlRUNDIXIDiE.
ii. Prognc concolor Allied to P. purpurea of North and South
America.
C<EREBIDiE.
6. Certhidea olivacea > A peculiar genus allied to the Andean
7. ** fusca > genus Coi»Vo»/rMW/.
Frinoillid^ic.
8. Geospiza magnirostris.
strenua
dubia
9.
10.
11.
12.
13.
H.
i *
15.
44
/ortis ^ A distinct genus, huL allied to the Soiiili
nebulosa
fuliginosa . .
parvula ....
dentiroitris
American genus Guiraca.
Chap.XIIL] the GALAPAGOS ISLANDS. 267
16. Cactomis icandens
17. '* assimilis . «• i * .i i ^
,o iL 'jf J ' >A genus allica to the last.
1 8. " Abingdoni '
19. ' " pallida
20. Camarhynchus psittaculas.,
Q,^ J J . (A very pecnliar genus allied to iVisorAjfii-
""* ,, ^ '^ff ** "f I ckus of the TFest coast of Peru.
23. ' ' prosthemelas
21. " Habeii
ICTKBIDJE.
2o. Dolichonyx oryzivora Ranges from Canada to Paraguay.
TTRAMMIDiE.
26. Pyrocephalus nanus Allied to P, rubineua of Ecuador.
27. Myiarchus magniroslris Allied to West Indian species.
COLUMBIDiE.
28. Zenaida Galapagotntii A peculiar species of a South American
genus.
FALCOMIDiE.
20. Butto Galapagoensis A buzzard of peculiar coloralion.
STRIGIDiE.
30. Aslo Galapagoensis Hardly distinct from the wide-spread A.
brachyotus.
31 . Strix punctatissima Allied to S.Jlammea, but quite distinct.
We have here every gradation of difference, from perfect
identity with the continental species to genera so distinct that
it is difficult to determine with what forms they are most nearly
allied ; and it is interesting to note that this diversity bears a
distinct relation to the probabilities of, and facilities for, migra-
tion to the islands. The excessively abundant rice-bird, which
breeds in Canada and swarms over the whole United States, mi-
grating to the West Indies and South America, visiting the dis-
tant Bermudas almost every year, and extending its range as far
as Paraguay, is the only species of land bird which remains
completely unchanged in the Galapagos ; and we may therefore
conclude that some stragglers of the migrating host reach the
islands sufficiently often to keep up the purity of the breed.
Next, we have the almost cosmopolite short-eared owl {Asio
brac/iT/otus), which ranges from China to Ireland, and from
Greenland to the Strait of Magellan, and of this the Galapagos
ISLAND LIFE.
[PuiTlL
bird 16 probably only one of the nuineroua varieties. Tlie little
wood-warbler {Dendrwca amvola) is closely allied to a species
which ranges over the whole of North America and as far eonth
as New Granada. It has also been occasionally met with in Ber-
muda, an indication that it Las considerable powei-s of flight and
cndm-ance. The more distinct species — as the inocking-thrushes
(Mimus), the tyrant fly-catchers (Pyroeephaliis and Myiarchns),
and the ground-dove (Zenaida) — are all allied to non-migratory
species peculiar to tropical America, and of a mure restricted
range; while the distinct genera are allied to South American
groups of finches and sugar-birds which have usually restricted
ranges, and whose habits are such as not to render them likely
to be carried out to sea. The remote nncesti'al forms of these
birds which, owing to somo exceptional canses, reached the tial-
apagos, have thus remained nninflnenced by later migrationti,
and have iu consequence been developed into a variety of dis-
tinct types adapted to the peculiar conditions of existence under
which they have been placed. Sometimes the different species
thus formed are conlined to one or two of the islands only, as
the two species of Certhides, which are divided between the isl-
ands, hut do not appear ever to occur together. Mimus parvulus
19 confined to Albemarle Island, and M. tr-ifaaciatus to Charles
Island J C'actornis paU'ula to Indefatigable Island, and C. Abinff-
doni to Abingdon Island.
Now all these phenomena arc strictly consistent with the tlie-
ory of the peopling of the islands by accidental migrations, if
we only allow them to have existed for a sufficiently long peri-
od ; and the fact that volcanic action has ceased on many of the
islands, as well as their great extent, would certainly indicate a
considerable antiquity.
■The great difference presented by the birds of these islands
as compared with those of the equally remote Azoi-es and Ber-
mudas is snfiSciently explained by the difference of cliinatal con-
ditions. At the Ualapagos there are none of those periodic
storms, gales, and hurricanes which prevail in the North Atlan-
tic, and which every year carry some straggling biids of Europe
or North America to the former islands; while, at the same
time, the majority of the tropical American birds are non-migra-
W»'%'i
Chap. XIII.] THE GALAPAGOS ISLANDS. 261>
tory, and thus afford none of the opportunities presented by the
countless hosts of migrants which pass annually northward and
southward along the European and especially along the North
American coasts. It is strictly in accordance with these different
conditions that we find in one case an almost perfect identity
with, and in the other an almost equally complete diversity
from, the continental species of birds.
Insects and Land Shells. — The other groups of land animals
add little of importance to the facts already referred to. The
insects are very scanty; the most plentiful group, the beetles,
only furnishing about thirty-five species, belonging to twenty-
nine genera and eighteen families. The species are almost all
peculiar, as are some of the genera. They are mostly small
and obscure insects, allied either to American or to world-wide
groups. The CarabidflB and the Heteromera are the most abundant
groups, the former furnishing six and the latter eight species.*
* The following list of the beetles yet known from the Gnlnpngos shows their
scanty proi)ortiuiis and accidental character; the thirty-seven siiecies bch)nging to
thirty-one genera and eighteen families. It is taken from Mr. Waterhouse's enu-
meration in the Proceeding of the Zoological Society for 1877 (p. 81) :
Carabid^. Nkcropraoa.
Feronia cahuhoides. Acribis semitix-entris.
** insiiiaiis. Phalacriis Darwinii.
i(
Gahipagoensis. Dermestes vulpinus.
Amblygnnilius obscuricomis. CcRCOUoNiDiE.
Solcnophorns Galapagoensis. Otiorhynchus cnneiformis.
Notapims Galapagoensis. Anchouus Galapag«»en»is.
Dyti8cid.£. Loxoicounia.
Eunectes occidenUilis. Ebuiia araabilis.
Malacodkrms. Hetkromrba.
Ablechrus Darwinii. Stomion lielopoides.
Coryneies rufii^s. ** lasvigiitum.
Bos'tricliiia nnciniatus. Ammophorus obscums.
Lambllicornks. ** Cookaoni.
^ . I , . bifoveatns.
Copns 1"«"»«. PedonoBces Galupag.Hsnsis.
Orycies Galapagoensis. ., pubeiceus.
hLATKRiDiC. Phalerin manicata.
Physorhinus Galapagoensis. Anthribidje.
AciliuH incisus. Ormiscus vaiiegaius.
Copelatiis Gahipagoensis. Phytopiiaoa.
Pai.picornes. Piabrotica limbata,
Tro])i8tcniiis lateralis. Docema Galapagoensis.
Philhydriis sp. Longitiirsus lunatus.
STAPIlYLlNIDiB, SkcURIPALPES.
Creophilus villosus. Scymnus Galapagoensis.
arc
ISLAND LIFE.
[P*M II.
The land shells are not abundant — about twenty in all, most
of them peculiar species, but not otherwise remarkable. The
observation of Captain Collnet, quoted by Mr, Darwin in hie
"Journal," that drift-wood, bamboos, canes, and the nuts of a
palm are often ^vaslied on the soutlieastern shores of the isl-
ands, furnisiies an excellent clew to the manner in which many
of the insects and land shells may have rciiched the Galapagos.
Whirlwinds also have been known to carry quantities of leaves
and other vegetable debris to great heiglits in the air, and these
might bo tlien carried away by strong upper currents and
dropped at great distances, and with tlieni small insects and
niollusca, or their eggs. We must also remember that volcanic
islands are subject to subsidence as well as elevatiou ; and it is
quite possible tliat during the long period the Galapagos have
existed soine islands may liavo intervened between them and
the coast, and have served as stepping-stones by which the pas-
sage to them of various organisms would be greatly f.icilitated.
Sunken banks, the relics of such islands, are known to exist in
many parts of the ocean, and countless others, no doubt, remain
undiscovered.
Tfie Keding Ixlamh as lUustratiny the Maimer in which
Oceanic /elands are Peopled. — That such causes as have been
here adduced are those by which oceanic islands have been peo-
pled is further shown by the condition of equally remote islands
which we know are of comparatively recent origin. Sncb are
the Keeling or Cocos Islands in the Indian Ocean, situated
about the same distance from Sumatra as the Galapagos from
South America, but mere coral reefs, supporting abundance of
cocoa-nut palms as their chief vegetation. These islands were
visited by Mr. Darwin, and tlieir natural history enrefnily ex-
amined. The only mammals are rata brought by a wrecked
vessel, and said by Mr. Wateriiouse to be common EnglisJi i-ats,
"but smaller and more brightly coloi-ed;" so that wc have here
an illustration of how soon a difference of race ia established
under a constant and uniform difference of conditions. There
are no true land birds, bnt there are snipes and rails, both ap-
parently common Malayan species. Ilcptiles are represented by
one small lizard, but no account of this is given in tlie " 2!oology
Chap.XIIL] the GALAPAGOS ISLANDS. 271
of the Voyage of the Beagle," and we may therefore conclude
that it was an introduced species. Of insects, careful collect-
ing only produced thirteen species belonging to eight distinct
orders. The only beetle was a small Elater, the Orthoptera
were a Gryllus and a Blatta ; and there were two flies, two ants,
and two small moths, one a Diopsea which swarms everywhere
in the eastern tropics in grassy places. All these insects were,
no doubt, brought either by winds, by floating timber (which
reaches the islands abundantly), or by clinging to the feathers
of aquatic or wading birds; and we only require more time, to
introduce a greater variety of species, and a better soil and more
varied vegetation, to enable them to live and nmltiply, in order
to give these islands a fauna and flora equal to those of the Ber-
mudas. Of wild plants there were only twenty species, belong-
ing to nineteen genera and to no less than sixteen natural fami-
lies, while all were common tropical shore plants. These islands
are thus evidently stocked by waifs and strays brought by the
winds and waves ; but their scanty vegetation is mainly due to
unfavorable conditions — the barren coral rock and sand, of which
they are wholly composed, together with exposure to sea-air, be-
ing suitable to a very limited number of species which soon
monopolize the surface. With more variety of soil and aspect
a greater variety of plants would establish themselves, and these
would favor the preservation and increase of more insects, birds,
and other animals, as we And to be the case in many sniall and
remote islands.*
' Junn Fernandez is a good cxnmple of a smaU island wliich, with time and favor-
able conditions, has acquired a tolerably rich and highly peculiar flora and fauna. It
is situated in 34^ 8. lat., 400 miles from tlie coast of Chili, and, so far as facilities for
the transport of living organisms arc concerned, is by no means in a favorable posi-
tion, for the ocean currents come from the southwest in a direction where there is
no land but the antarctic continent, and the prevalent winds are also westerly. No
doubt, however, there are occasional storms, and there may have been intermediate
islands; but its chief advantages are, no doubt, its antiquity and its varied surface,
ortering many chances for the preservation and increase of whatever plants and ani-
mals have chanced to reach it. The island consists of basalt, greenstone, and other
ancient rocks, and, though only about twelve miles long, its mountains are three
thousand feet high. lOnjoying a moist and temperate climate, it is especially adapted
to the growth of ferns, which are very abundant ; and as the spores of these plants
are as fine as dust, and very easily carried for enormous distances by winds, it is not
am
JSLANO XJITE.
[PuTlL
Flora of t/us Galapagos. — The plants of tlicae ielands are eo
niiicli moro nnmeroiis tlian the known animals, even including
the insects, they have been so carefully stndiad hy eminent
botanists, and their relations throw so much light on tlie past
history of the gi'oup, that no apology is needed for giving a
brief outline of iho peculiarities and affinities of the fioi-a. The
stnteincnta we sliall make on this subject will be taken from the
memoir of Sir Joseph Hooker in the Limiixan Transactions for
1851, founded on Mr. Darwin's collections, and a later paper by
N. J, Andersson in the Linnmt of 1861, embodying more recent
discoveries.
Tlie total number of flowering plants known at the latter date
was 332, of which 174 were peculiar to the islands, while 158
wore common to other countries. Of these latter abont 20 have
been introduced by man, while the remainder arc all natives of
some part of America, tliougli abont a tliird part are species of
wide range extending into botli hemispheres. Of those confined
to America, 42 are found in both the northern and southern
continents, 21 are confined to South America, while 20 are
found only in North America, the West Indies, or Mexico.
This equality of North American and South American Epecics
in the Galapagos is a fact of great significance in connection
with the observation of Sir Joseph Hooker, that the peculiar
species are allied to the plants of temperate America or to those
of the high Andes, while the non-peculiar species are mostly
turpriaing rlinl there arv ttrcnty-foiir spcciet on (he i<i1nnd, nliiln llic remote period
when il Hot leceireJ im vegetnlioii may ba inilieiiled b; llio Tiict llmt fuiir oC ilia
■|ie('l(u nil] qiiiie peculiar. The Mine genernl charncter pervades the whole flurn
nnil r»iiiiit. For so sroiill an Islniid it is rii:h, coninimng a conaiilcrnUe number of
Boweriiig pliiiits four inie lnn<l birilt, nhnnt fifty upecie* of insecta, nnd Iwenir ti(
binil fihallR. AlntiiBi nil lliete ticliiiig to Soiilli Ainericnii genem, nnd a Inrge prapui-
liun RTe SiHilli Ameticnn 8|>etic8i but sereral of llie ])lnnu nnd insects, liair ilia
birdi, and the n hole oT ilia Innd ilicUn nre peviilinr. 'J'hia seems to indicnie thni ilia
■nemtg uf imiisniiMioii (reiti fiinnerlr grcmer (hiu) titty me nniv, nnd tlini in th* can
oTIniid ahells ni>i>e hnve tteeii iiitrodupod fur to lung a |«Hod that nil hnve become
modidod into Uistlitcl furmi, or have been prcaerved on the island nhile tliey hava
bocomc exiliiei on tlie coniinenl. For n delailod nxiitninnlion of ilia cuimes wliieh
hav« led to ihe modi lien Hnii Dflhe hiimtniiiQ- birds of Jiian Fernandea. see the an-
ihor'i "Trupirid Nniure,"p. 110; white n Rvncral lu-coiini ofilic faDiinorilie isUtid
Ugivon ill Ilia " Geogrnphical Uiirribuiion of Anintiil*," Vol, 11., p. tU.
Chap.XIH.] TUE GALAPAGOS ISLANDS. 273
such as inliabit the Iiotter regions of the tropics near the level
of the sea. He also observes that the seeds of this latter class
of Galapagos plants often liave special means of transport, or
belong to groups whose seeds are known to stand long voyages
and to possess great vitality. Mr. Bentham, also, in his elaborate
account of the Compositse,* remarks on the decided Central
American or Mexican affinities of the Galapagos species, so that
we may consider this to be a thoroughly well-established fact.
The most prevalent families of plants in the Galapagos are
the Compositae (40 species), Gramineae (32 species), Leguminos©
(30 species), and Euphorbiaceae (29 species). Of the Compositae
most of the species, except such as are common weeds or shore
plants, are peculiar, but there are only two peculiar genei*a allied
to Mexican forms and not very distinct ; while the genus Lipo-
chaeta, represented here by a single species, is only found else-
where in the Sandwich Islands, though it has American affin-
ities.
OrUjin of the GoLapagos Flora. — These facts are explained by
the past history of the American continent, its separation at va-
rious epochs by arms of the sea uniting the two oceans across
what is now Central America (the last separation being of re-
cent date, as shown by the identical species of fishes on both
sides of the isthmus), and the influence of the glacial epoch in
driving the temperate American flora southwai*d along the
mountain plateaus.' At the time when the two oceans were
united, a portion of the Gulf Stream may have been diverted
into the Pacific, giving rise to a current, some part cf which
would almost certainly have reached the Galapagos, and this
may have helped to bring about that singular assemblage of
West Indian and Mexican plants now found there. And as we
now believe that the duration of the last glacial epoch in its suc-
cessive phases was much longer than the time which has elapsed
since it finally passed away, while throughout the Miocene epoch
the snow-line would often be lowered during periods of high
eccentricity, we are enabled to comprehend the nature of the
* Journal of the Linnaan Society^ Vol. XIII., Botnny, p. 556.
' ** Geographical Distribution of Animnla," VoL II., p. SL
18
97+
ISLAND LIFR,
Tir.
canses wliieli may Jiave lot! to tlie islands being etoeked with
those northern or eubalpine types which are so ehamctcristic a
feature of that portion of the Galapagos flora which conei&ts of
peculiar species.
On the whole, the flora agrees with the fauna in indicating a
moderately remote origin, great isolation, and changes of condi-
tlona affording facilities for the introdnction of organisma from
various parts of the Ameriean coast, and oven from the West
Indian Islands and Gulf of Mexico. Aa in the case of the birds,
tl)e several islands differ considerably in their native plants,
many species being limited to one or two islands only, while
others extend to several. This is, of course, what might be ex-
pected on any theory of their origin ; because, even if the whole
of the islands had once been united and afterwards separated,
long-continued isolation would often load to the differentiation
of species, while the varied conditions to be found upon islands
differing in sizo and altitude as well as in Insuriance of vegeta-
tion would often lead to the extinction of a species on one isl-
and and its preservation on another. If the several islands had
been eijually well explored, it might be interesting to see wheth-
er, as in the case of the Azores, the number of species diminished
in those more remote from the coast; but, unfortunately, our
knowledge of the productions of the various islands of tlie group
in exceedingly nne<]ual, and, except in those cases in which re\>
resentative species inhabit distinct islands, we have no certainty
on the subject. All the more interesting problems in geograph-
ical distribution, however, arise from the relation of the fauna
and flora of the group as a whole to those of the surrounding
continents ; and we shall therefore, for the moat part, confine our-
selves to this aspect of the question in our discussion of tlic phe-
nomena presented by oceanic or continental islands.
Conclvding lianarkv. — The Galapagos offer an instructive
contrast with the Azores, showing how a difference of conditions
that might be tliought unimportant may yet produce very strik-
ing results in the forms of life. Although the Galapagos are
much nearer a continent than the Azores, the number of speelea
of i)lant8 common to the continent Is mucli Jess in the former
case than in the latter, and thia is still more prominent a clmrnc-
Chap. XIII.] THE GALAPAGOS ISLANDS. 275
teristic of the insect and the bird fauna. This difference has
been shown to depend almost entirely on the one archipelago
being situated in a stormy, the other in a calm, portion of the
ocean ; and it demonstrates the preponderating importance of
the atmosphere as an agent in the dispei*sal of birds, insects, and
plants. Yet ocean currents and surface drifts are undoubtedly
efficient carriers of plants, and, with plants, of insects and shells,
especially in the tropics ; and it is probably to this agency that
we may impute the recent introduction of a number of common
Peruvian and Chilian littoral species, and also at a more remote
period of several West Indian types when the Isthmus of Pana-
ma was submerged.
In the case of these islands we see the importance of taking
past conditions of sea and land and past changes of climate into
account, in order to explain the relations of the peculiar or en-
demic species of their fauna and flora ; and we may even see an
indication of the effects of climatal changes in the Northern
Hemisphere, in the north temperate or Alpine affinities of so
many of the plants, and even of some of the birds. The relation
between the migratory habits of the biixis and the amount of
difference from continental types is strikingly accordant with
the fact that it is almost exclusively migratory birds that annu-
ally reach the Azores and Bermuda ; while the corresponding
fact that the seeds of those plants which are common to the
Galapagos and the adjacent continent liave all — as Sir Joseph
Hooker states — some special means of dispersal is equally intel-
ligible. The reason why the Galapagos possess four times as
many peculiar species of plants as the Azores is clearly a result
of the less constant introduction of seeds, owing to the absence
of storms; the greater antiquity of the group, allowing more
time for specific change; and the influence of cold epochs and
of alterations of sea and land in bringing somewhat different sets
of plants at different times within the influence of such modi-
fied winds and currents as might convey them to the islands.
On the whole, then, we have no difficulty in explaining the
probable origin of the flora and fauna of the Galapagos by
means of the illustrative facts and general principles already
adduced.
ISLAND LIFE.
CHAPTER SIV.
ST. IlKLESA.
1*0*111011 mid I'hj'siciil Feaiures of Si, Ueleiin.— Change Effected by ILiiropoan Oc-
cupftlion.— Tlie liisecia of St. Helena. — C'-uIeojireru. — reculinrJLlea and Oiigin iif
the Coleoplei'A of St. Helena. — Land SJielli of Si. Helenn. — ALcence of Fresli-
w«ier Oripinunis. — Xnilve Vegeiation of St. Uelenn. — The Belnliona of tli« Sr.
Ileleiiit Cumposiia. — CODcludliig Itemarka on St. Uelenn.
In order to illustrate as completely as possible tiie peculiar
phenomena of oceanic ielanda, we will next examine the organie
productions of St. Helena, and of the Sandwich lelande, since
these combine in a higher degree than any other spots upon tlio
globe extreme isolation from all more extensive lands ^vitll a
tolerably rich fauna and fiora whose peculiarities are of surpass-
ing interest. Both, too, have received considerable attention
from naturaiiets; and though much still remains to be done in
the latter group, our knowledge is sufficient to enable lis to ar-
rive at many interesting results.
I'ou'dion and Physical Features of St. Helena. — This island
is situated nearly in the middle of the South Allantic Ocean,
being more than 1100 miles from the coast of Africa, and 1800
from South America. It is about ten miles long by eight wide,
and is wholly volcanic, consisting of ancient basalts, lavas, and
other volcanic products. It is very mountainous and rugged,
bounded, fur the most part, by enormous precipices, and rising to
a, height of 2700 feet above the sea-level. An ancient crater,
about four miles across, is open on the south side, and its north-
ern rim forms the highest and central ridge of the island.
Many other bills and peaks, liowever, are more than two thou-
sand feet high, and a considerable portion of the snvface consists
of a rugged plateau, having an elevation of about fifteen hundred
to two thousand fcot. Everything indicates that St, Helena is
SYS
ISJJ&ND LIFB.
[Pabi IL
ail isolateii volcanic lunsa built up from the depths of tlic ocean.
Mr. WoUastoii remarkB, " Tliere are the strongest reasons for
believing that the area of St. Helena was never -cenj much larger
than it is at present — the comparatively shallow sea-sou ntl in t[3
within about a mile and a half from the shore revealing an
ahniptly delincd ledge, beyond which no bottoin is reached at a
depth of 250 fathoms; so that the original basaltic mass, wiiich
was gradiially piled up by means of successive eruptions from
beneath the ocean, would appciir to Jiavo its limit definitely
marked out by this suddenly terminating submarine cliff — the
space between it and the existing coast-lUie being reasonably re-
ferred to that slow process of disintegration by which the ishmd
has been reduced, tlirongh the eroding action of the elements,
to its present dimensions." If we add to this that between the
island and the coast of Africa, in a southeasterly direction, is a
profound oceanic gnlf known to reach a depth of 286U fulhoms,
or 17,100 feet, while an ei^iially deep, or perhaps deeper, ocean
extends to the west and sontliwcst, we shall bo satisfied that St.
Helena is a true oceanic island, and that it owes none of its pe-
ciilinritics to a former union with any continent or other distant
land.
Chawje Efftdfid hy European Occupation. — When firat dis-
covered, 37S years ago, St. Helena was densely covered with a
Inxiiriant forest vegetation, the trees overhanging the seaward
precipices and covering every part of the surface with an ever-
green mantle. This indigenous vegetation lias been almost
wholly destroyed ; ami although an immense number of foreign
plants have been introduced, and have more or less completely
established themselves, yet the general aspect of llio island is
now so barren and forbidding that some persons find it diflicnlt
to believe that it was once all green and fertile. The cause of
the change is, however, very easily explained. Tlie rich soil
formed by decomposed volcanic rock and vegetable deposits
could only be retained on the steep slopes so long us it was pro-
tected by the vegetation to whicli it in great part owed its origin.
When this was destroyed, the heavy tropical rains soon washed
away the soil, and has left a vast expanse of bare rock or sterile
clay. This irreparable destruction was cansed, in the first pLice,
Chap. XIV.] ST. HELENA. 279
by goats, which were introduced by the Portuguese in 1513,
and increased so rapidly that in 1588 they existed in thousands.
These animals are the greatest of all foes to trees, because they
eat oflE the young seedlings, and thus prevent the natural resto-
ration of the forest. They were, however, aided by the reckless
waste of man. The East India Company took possession of the
island in 1651, and about the year 1700 it began to be seen that
the forests were fast diminishing, and required some protec*
tion. Two of the native trees, redwood and ebony, were good
for tanning, and, to save trouble, the bark was wastefully stripped
from the trunks only, the remainder being left to rot ; while in
1709 a largo quantity of the rapidly disappearing ebony was
used to burn lime for building fortifications ! By the MS. rec-
ords quoted in Mr. Melliss's interesting volume on St. Helena,*
it is evident that the evil consequences of allowing the trees to
be destroyed were clearly foreseen, as the following passages
show : " We find the place called the Great Wood in a flourish-
ing condition, full of young trees, where the hogs (of which there
is a great abundance) do not come to root them up. But the
Great Wood is miserably lessened and destroyed within our
memories, and is not near the circuit and length it was. But wo
believe it does not contain now less than fifteen hundred acres
of fine woodland and good ground, but no springs of water but
what is salt or brackish, which we take to be the reason that that
part w^as not inhabited when the people first chose out their
settlements and made plantations; but if wells could be sunk,
which the governor says he will attempt when we have more
hands, we should then think it the most pleasant and healthiest
part of the island. But as to healthiness, we don't think it will
hold so if the wood that keeps the land warm were destroyed ;
for then the rains, which are violent here, would carry away
the upper soil, and, it being a clay marl underneath, would pro-
duce but little ; as it is, we think in case it were enclosed it
might be greatly improved. . . . When once this wood is gone,
the island will soon be ruined. . . . We viewed the wood's
* ** St. Helena: a Pliysical, Ilistoricnl, and Topograpliical Description of the Isl-
and," etc., by John Charles Melliss, F.G.S., etc. London, 1875.
ISLAND LIFK
[PiBTlI.
end wbicli joins the Honorable Company's plantation called the
Hutts, but the wood is so destroyed that the beginning of the
Great Wood is now a whole mile beyond that place ; and all the
Boil being washed away, that distance is now entirely barren"
(MS, llccords, 1716). In 1709 the governor reported to the
Court of Uirectoi-B of the East India Company that tlio timber
was rapidly disappearing, and that the goats should be destroy-
ed for the preservation of the ebony wood, and because the isl-
and was suffering from droughts. The reply was, "The goats
are not to be destroyed, being more valuable than ebony." Thus,
through tiic gross ignorance of those in power, the last oppor-
tunity of preserving the peculiar vegetation of St. Ilelena, and
preventing the island from becoming the comparatively rocky
desert it now is, was allowed to pass away.' Even in a mere
pecuniary point of view, the error was a fatal one, for in the next
eentnry (iu 1810) another governor reports the total destruction
of the great forests by the goats, and that in coneequeueo the
cost of importing fuel for government use was £2729 7s. 8d. for
a single year I- About this time large numbers of European,
American, Australian, and South African plants wero imported,
and many of these ran wild and increased so rapidly as to drive
out and exterminate mncli of the relics of tho native Hora; so
that now English broom, gorso and brambles, willows and pop-
I Mr. Mnrali. in hia intorwlidg work entitled "The Earth as MoJlflcd by Hiiuuin
Aciiini"(p. Gl). tlimreranrki mi tlia c^Tect of browsing qiisd raped a in dcsi roving nnd
cliecking woody vegotation : " I am convinced ihot htetu noald BOon cover many jinrts
of ihB Arnbiun and Africnn dcwns if mnii and domestic animals, eHpeciallr ilie gont
nnd the cAmel, vtMi banitlied from llicm. The hnrd paliiie and inngue nnd Btrong
teeth and jnwi of Ibis latter qundniped enable liim lo brcnk off and mnstlente tough
nndibomybrancliesnslnrgenBihBflneer. Ileisparticulnrlyfondof iheamollertwigF,
tenvea, nndaeed-podiof lliG^anfond olUer aonclni, whicfi.likeihe American Kobinin,
lUriie well on dry and sandy loils ; and he ipnrM no tree the branclies of wliich are
within hi] readi, except, if I lemcnibcr right, t)ic tamarisk that producei mnnnn.
Young trees iproul plentifully around ilid «|irine> |fid along the winter wBter-eouraei
of tho desert, and Iheae are just ih« ha[ting-»tai<on> of the cnravana and tlicir roulo*
of travel. In the shade of these iroci, antinni gmases and perennial ebrubs thool tip,
but ma mown down by the hungry coiiIe of the Itedouin ns fust as they grow. A
few yean of undialurbcd vegetation would siiHIce to cover such points with (trores,
and thioe would Bnidually extend tliemMlve* over soils where now scarcely nny greeu
thing lint the bitter colocynih nnJ the poifonons fox-glove is ever seen."
Chap. XIV.] ST. HELENA. 281
lars, and some common American, Cape, and Australian weeds,
alone meet the eye of tlie ordinary visitor. These, in Sir Joseph
Hooker's opinion, render it absolutely impossible to restore the
native flora, which only lingers in a few of the loftiest ridges
and most inaccessible precipices, and is rarely seen except by
some exploring naturalist.
This almost total extirpation of a luxuriant and highly pecul-
iar vegetation must inevitably have caused the destruction of a
considerable portion of the lower animals which once existed on
the island, and it is rather singular that so much as has actually
been discovered should be left to show us the nature of the
aboriginal fauna. Many naturalists have made small collections
during short visits, but we owe our present complete knowledge
of the two most interesting groups of animals — the insects and
the land shells — mainly to the late Mr. T. Vernon Wollaston,
who, after having thoroughly explored Madeira and the Cana-
ries, undertook a voyage to St. Helena for the express purpose
of studying its terrestrial fauna, and resided for six months
(1875-76) in a high central position, whence the loftiest peaks
could be explored. The results of his labors are contained in
two volumes,* which, like all that he wrote, aiX3 models of accu-
racy and research, and it is to these volumes that we are indebt-
ed for the interesting and suggestive facts which we here lay
before our readers.
Insects — Coleoptera. — The total number of species of beetles
hitherto observed at St. Helena is 203 ; but of these no less
than 74 are common and wide-spread insects, which have cer-
tainly, in Mr. Wollaston's opinion, been introduced by human
agency. There remain 129, which are believed to be truly ab-
origines, and of these all but one are found nowhere else on the
globe. But, in addition to this large amount of specific pecu-
liarity (perhaps unequalled anywhere else in the world), the
beetles of this island are equally remarkable for their generic
isolation, and for the altogether exceptional proportion in which
the great divisions of the order are represented. The species
belong to thirty-nine genera, of which no less than twenty-five
1 (t
Coleoptera Sanct» Helenic," 1877; "Testocea Atlnntica," 1878.
ISLAND LIFE,
[PiBlU.
are peculiar to tlie island; and mnny of these are siicli isoluted
forms that it k impossililo to linJ their allies ia any particular
country. Still more rciniirkahle is thu fact that more than two
thirds of the whole nimiher of itidigenoua sjjeciijs are Ithyiicoph-
ora, or weevils, while more than two tifths (tifty-fonr speuies) be-
long to one family, the Cossonidie. Now, although the Jlhyn-
cophora are an immensely numerons group and always form a
large portion of the insect population, they nowhere else ap-
proach such a proportion as this. For example, in Madeira they
form one si.xth of the whole of the iudigeuous Coleoptera, in
the Azores less than one tenth, and in Britain one Beventli.
Even more interesting is the fact that the twenty genera to
which these insects belong are every one of them peculiar to
tlie island, and in many cases have no near allies elsewhere, so
that we cannot hot look on this group of beetles as forming the
most characteristic portion of the ancient insect fauna. Now,
as the groat majority of these are wood-borers, and all arc closely
attached to vegetation, and often to particular epecics of plants,
we might, as Mr. Wollaston well observes, dcduco the former
Inxuriant vegetation of the island from the great preponderance
of this group, oven had wo not positive evidence that it was
at no distant epoch densely forest-chid. We will now proceed
briefly to indicate the numbers and peculiaiitiea of each of the
families of liectles which enter into the St, Helena fauna, taking
them, not in systematic order, hut according to their importance
in the island.
1. ItuyNL-QPuoBA. — This great division includes the weevils
and allied groups, and, as above stated, exceeds in number of
species all the other beetles of tlio island. Four families are
represented; the Cossonidie. with fifteen peculiar genera com-
prising fifty-four species, aud one minute insect {Sl^noscdts hy-
Uuitoi<Je») forming a peculiar genus, hut ■which has been found
also at the Cape of Good IJope. It is therefore impossible to
say of which country it is really a native, or whether it is indig-
enous to both, aud dates back to the remote period when St.
Helena received its early immigrants, All tho Coesonida; are
found in the highcEt and wildest parts of the island where the
native vegetation still lingers, aud many of them are only found
CiLiP. XIV.] ST. HELENA. 283
in the decaying steins of tree-ferns, box-wood, arborescent Com-
positae, and otlier indigenous plants. They are all pre-eminently
peculiar and isolated, having no direct affinity to species found
in any otlier country. The next family, the Tanyrhynchidae, has
one peculiar genus in St. Helena, with ten species. This genus
(Xesiotes) is remotely allied to European, Australian, and Ma-
deiran insects of the same family : the habits of the species are
similar to those of tlie Cossonidce. The Trachyphloeidse are repre-
sented by a single species belonging to a peculiar genus not very
remote from a European form. The Anthribidae, again, are high-
ly peculiar. There are twenty-six species, belonging to three
genera, all endemic, and so extremely peculiar that they form
two new sub-families. One of the genera, Acarodes, is said to
bo allied to a Madeiran genus.
2. Geodepiiaoa. — These are the terrestrial carnivorous beetles,
very abundant in all parts of the world, especially in the tem-
perate regions of the Northern Hemisphere. In St. Helena
there are fourteen species, belonging to three genera, one of
which is peculiar. This is the llaplothorax BurcheUii^ the largest
beetle on the island, and now very rare. It resembles a large
black Carabus. There is also a peculiar Calosoma, very distinct,
though resembling in some respects certain African species.
The rest of the Geodephaga, twelve in number, belong to the
wide-spread genus Bembidium ; but they are altogether peculiar
and isolated, except one, which is of European type, and alone
has wings, all the rest being wingless.
3. IIetkeomera. — This group is represented by three peculiar
genera containing four species, with two species belonging to
European genera. They belong to the families Opatridte, Mor-
dellid^e, and Anthicidse.
4. Bkaciiyelytka. — Of this group there are six peculiar spe-
cies, belonging to four European genera — Homalota, Philonthus,
Xantholinus, and Oxytelus.
5. Priocerata. — The families Elateridre and Anobiidae are
each represented by a peculiar species of a European genus.
0. PiiYTopiiAOA. — There are only three species of this tribe,
belonging to the European genus Ix)ngitarsu8.
7. Lamellicornis. — Here are three species, belonging to two
964
ISLAND LIFE.
[P*B
genera. Oiic is a peculiar species of Trox, allied to South Afri-
can forms; tbe other two belong to the pecnliar genus Meliseiiis,
which Mr. AVollaston considers to be remotely allied to Austra-
lian insects.
8. PsErDo-TRraERi. — Here mg liave the fine lady-bird Chtlo-
vienus lunata, also found in Africa, but apparently indigenous
in St. Helena ; and a peculiar species of Eusestes, a genua only
found elsewhere in Madeii'a.
9. TiucuopTERVGiD^. — Tliese, the minutest of beetles, are rep-
resented by one species of the European and Madeiran genus
Ptinella.
10. Neckophaga, — One indigenous apeeioe of Cryptophnga
inhabits St. Helena, and this is said to be very closely allied to
a Cape species.
Peculiarities arid Origin of the Cohoptera of St. Helena. —
We see that the great mass of the indigenous species are not
only peculiar to the island, but so isolated in their characters as
to show no close affinity with any existing insects ; while a small
number (about one third of the whole) have some relations,
though often very remote, with species now inhabitiug Europe,
Madeira, op South Africa. These facts clearly point to the very
great antiquity of the insect fauna of St. Helena, which has al-
lowed time for the modification of the originally introduced spe-
cies, and their special adaptation to the conditions prevailing in
this remote island. This antiquity is also shown by the remark-
able specific modification of a few types. Thus the whole of
the Cossonidffi may be referred to three types, one species only
(Ilexacoptiig femtgineva) being allied to the European Cossoni-
dte, though forming a distinct genus ; a group of three genera
and seven species j'eniolely allied to the Htf^noscelis hylastoides,
which occnrs also at the Capo : while a group of twelve genera
with forty-six species have their only (remote) allies in a few
insects widely scattered in South Africa, New Zealand, Europe,
and the Atlantic islands. In like manner, eleven species of
Bembidium form a group by themselves; and the HeteroTuera
form two groups — one consisting of three genera and species of
Opatridffi allied to a type found in Madeira; the other, Antbico-
des, altogether peculiar.
Chap. XIV.] ST. HELENA. 285
Now each of these types may well be descended from a single
species which originally reached the island from some other
land ; and the great variety of generic and specific forms into
which some of them have diverged is an indication, and to some
extent a measure, of the remoteness of their origin. The rich
insect fauna of Miocene age found in Switzerland consists mostly
of genera which still inhabit Europe, with others which now in-
habit the Cape of Good Hope or the tropics of Africa and South
America ; and it is not at all improbable that the origin of the
St. Helena fauna dates back to at least as remote, and not im-
probably to a still earlier epoch. But if so, many diflBculties in
accounting for its origin will disappear. We know that at that
time many of the animals and plants of the tropics of North
America, and even of Australia, inhabited Europe ; while during
the changes of climate which, as we have seen, there is good
reason to believe periodically occurred there would be much
migration from the temperate zones towards the equator, and
the reverse. If, therefore, the nearest ally of any insular group
now inhabits a particular country, we are not obliged to suppose
that it reached the island from that country, since we know that
most groups have ranged in past times over wider areas than
they now inhabit. Neither are we limited to the means of trans-
mission across the ocean that now exist, because we know that
those means have varied greatly. During such extreme changes
of conditions as are implied by glacial periods and by warm polar
climates, great alterations of winds and of ocean currents are in-
evitable ; and these are, as we have already proved, the two great
agencies by which the transmission of living things to oceanic
islands has been brought about. At the present time the south-
east trade-winds blow almost constantly at St. Helena, and the
ocean currents flow in the same direction, so that any transmis-
sion of insects by their means must almost certainly be from
South Africa. Now there is undoubtedly a South African ele-
ment in the insect fauna, but there is no less clearly a European,
or at least a north temperate element, and this is very difficult
to account for by causes now in action. But when we consider
that this northern element is chiefly represented by remote ge-
neric affinitj', and has therefore all the signs of great antiquity,
ISLASD LIFK
CPiarlL
we find n po3sil>!e meaos of accounting for it. "We liave Been
that during early Tertiary times an ahiiogt tropical climate ex-
tended fur into tlio Northern Hemisphere, and a temperate cli-
mate to the arctic regionB. But if at this time (as is not im-
probable) the antarctic regions were as mtich ice-clad as they are
now, it is certain that an enormous change must have been pro-
duced in the winds. Instead of a great diiference of tempera-
ture between each pole and the equator, the difference would be
mainly between one hemisphere and the other, and this might so
disturb the trade-winds aa to bring St. Helena within the south
temperate region of storms — a position corresponding to that of
the Azores and Madeira in the North Atlantic, and thus subject
it to violent gales from all points of the compass. At tiiis re-
mole epoch, the monntains of e'|iiatoriaI Africa may have been
more extensivo than they are now, and may have served as in-
termediate stations by which some northern insects may Imvc
migrated to the Sonthern Hemisphero.
We mnat reniember,also,that these peculiar forms are said to
be northern only because their nearest allies are now found in
the North Atlantic islands and Southern £urope; but it is not
at all improbable that tliey are really wide-spread Miocene types
which have been preserved mainly in favorable insular stations.
They may, therefore, have originally reached St. Helena from
Southern Africa, or from some of the Atlantic islands, and may
have been convoyed by oceanic currents aa well as by winds.'
'OiiPeteiinaiin'iiinnpcifAfrici»inthenewoiiilionofSiielBr'ii''Uainl-AHiia"(IB79),
iha Inland ot A>cen«ii>ii it Bhonn ns aenicd on o mucli Inrger nnil ilia1lu\ver lubinit-
rine bank tlinii Si. Helenn. Tho lOOO-fiitliom line ronnil Aicension enrlii««s nn oiril
■)sce ITO miles tong by 70 wide, nnd even ilie ai)0-riuhom lino one over GO milea
tongi nnd it i> thererure probable thnt n much larger Ulnnd onfe occupied thU
■ite. Now Aiwensiun is nearly eqnidisinm lictween Si. Helena nnd Liberi*. and »ucU
Mti itland might liKva saned oi nn iniermeiJiiite ainlian through nliith many o( the
immigrntiu lo SL Helena pnsseJ. As the dislancei aro hnrdly grsnter limn in th«
CMS of the Axoi'e!!, ihia removes whatever difficult]' mnj' hnvo been fell of ihe poui-
hilii; of (uijr organiRins reaehing so remole an island. The prewnt Island ot Aieen-
tlon is prolinbly only Ihs summit of a linge volcanic maas, nnd any remnant ot tbo
original faimn nnd florn it might linve pi'escn'cd inny hnve been dettrorcd by gitKt
volcanic sruptioni. Mr. Dnrnin collecicd some miissos of tufa which were found lo
ba mainly orgnnic, coninining, be^iides remiiini; of fii»li-iviiier infiinorin, ihe uliccnns
lissiie of plunli ! In tlio liglii of ibc great exieni of tbo lubmnrinc bnnk on ivhieli
Chap. XIV.] ST. HELENA. 287
This 18 the more probable, as a large proportion of the St. Helena
beetles live even in the perfect state within the stems of plants
or trunks of trees, while the eggs and larvae of a still larger
number are likely to inhabit similar stations. Drift-wood might
therefore be one of the most important agencies by which these
insects reached the island.
Let us now see how far the distribution of other groups sup-
ports the conclusions derived from a consideration of the beetles.
The Hemiptera have been studied by Dr. F. Buchanan White;
and though far less known than the beetles, indicate somewhat
similar relations. Eight out of twenty-one genera are peculiar,
and the thirteen other genera are, for the most part, widely dis-
tributed, while one of the peculiar genera is of African type.
The other orders of insects have not been collected or studied
with sufficient care to make it worth while to refer to them in
detail ; but the land shells have been carefully collected and mi-
nutely described by Mr. Wollaston himself, and it is interesting
to see how far they agree with the insects in their peculiarities
and affinities.
Land Shells of St, Helena, — The total number of species is
only twenty-nine, of which seven are common in Europe or the
other Atlantic islands, and are, no doubt, recent introductions.
Two others, though described as distinct, are so closely allied to
European forms that Mr. Wollaston thinks they have probably
been introduced and have become slightly modified by new con-
ditions of life ; so that there remain exactly twenty species which
may be considered truly indigenous. No less than thirteen of
these, however, appear to be extinct, being now only found on
the surface of the ground or in the surface soil in places where
the native forests have been destroyed and the land not culti-
vated. These twenty peculiar species belong to the following
genera : Hyalina (3 sp.), Patula (4 sp.), Bulimus (7 sp.), Subulina
(3 sp.), Succinea (3 sp.) ; of which one species of Hyalina, three
of Patula, all the Bulirai, and two of Subulina are extinct. Tlie
the island 8tnnds, Mr. Darwin's remark, that **we may feel sure that at some former
epoch the climate and productions of Ascension were very different from what they
are now," has received a striking confirmation. (See ** Naturalist's Voyage round
the World," p. 405.)
388 ISUUID LIF£. [PaiitIL
three HyaliDas arc allied to European species, but all tlie rest ap-
pear to be iiiglily peculiar, and to liavu no near allies with the
species of any other country. Two of tlio Bulimi {B.auris -eul-
pinm and B. Darwinianui) are said to somewhat resemble Bm-
zilian, Kew Zealand, and Solomon Island forms, while neither
JJuInitUB nor Suceinea occurs at all in the Madeira group.
Omitting the speeies that have probably been introdnced Ity
human agency, we have here indications of a somewhat recent
immigration of European types which may perhaps he referred
to the glacial period; and a much more ancient immigration
from unknown lands, which must certainly date back to Miocene,
if not to Eocene, times.
Absence of Ft'csh-waUr Organisms. — A singular phenomenon
is the total absence of indigenous aquatic forms of life in St.
Helena. Not a single water-beetle or fresh-water shell has been
discovered; neither do there seem to be any water-plants in tlie
Btreama except the common water-ci-ess, one or two species of
Cyperus, and the Australian laapis proll/era. The same ab-
sence of fresh-water shells characterizes the Azores, where, how-
ever, there is one indigenous water-beetle. In the Sandwich
Islands also recent observations refer to the absence of water-
beetles, though here there are a few fresh-water shells. It would
appear, therefore, that the wide distribution of the same generic
and specific forms which so generally characterizes fresh-water
organisms, and which has been so well illustrated by Mr. Darwin,
has its limits in the very remote oceanic islands, owing to causes
of wLiicli we are at present ignorant.
The other classes of animals in St. Helena need occupy us lit-
tle. Tiiere are no indigcnons mammals, reptiles, fresh-water
I £sltes, or true land birds; but there is one species of wader — a
Binall plover {j£gialitis •Sanctm ffdejid) very closely allied to u
species found in South Africa, but presenting certain differences
which entitle it to the rank of a ])cculiar species. The plants,
however, are of especial interest from a geographical point of
view, and we must devote a few pages to their consideration as
supplementing the scanty materials afforded by the animal life,
thus enabling us bettor to undei-stand the biological relations
and probable history uf the island.
Chap. XIV.] ST. HELENA. 2S9
Native Vegetation of St, Helena. — Plants have certainly more
varied and more effectual means of passing over wide tracts of
ocean than any kinds of animals. Tlieir seeds are often so mi-
nute, of such small specific gravity, or so furnished with downy
or winged appendages, as to be carried by the wind for enor-
mous distances. The bristles or hooked spines of many small
fruits cause them to become easily attached to the feathers of
aquatic birds, and they may thus be conveyed for thousands of
miles by these pre-eminent wanderers ; while many seeds are so
protected by hard outer coats and dense inner albumen that
months of exposure to salt water does not prevent them from
germinating, as proved by the West Indian seeds that reach the
Azores or even the west coast of Scotland, and, what is more to
the point, by the fact stated by Mr. Melliss, that large seeds
which have floated from Madagascar or Mauritius round the
Cape of Good Hope have been tlirown on the shores of St.
Helena and have then sometimes germinated !
We have therefore little difficulty in understanding how the
island was firet stocked with vegetable forms. IVhen it was so
stocked (generally speaking) is equally clear. For, as the pecul-
iar Coleopterous fauna, of which an important fragment remains,
is mainly composed of species which are specially attached to
certain groups of plants, we may be sure that the plants were
there long before the insects could establish themselves. How-
ever ancient, then, is the insect fauna, the flora must be more
ancient still. It nmst also be remembered that plants, when
once established in a suitable climate and soil, soon take posses-
sion of a country, and occupy it almost to the complete exclusion
of later immigrants. The fact of so many European weeds hav-
ing overrun New Zealand and temperate North America may
seem opposed to this statement, but it really is not so. For in
both these cases the native vegetation has first been artificially
removed by man and the ground cultivated; and there is no
reason to believe that any similar effect would be produced by
the scattering of any amount of foreign seed on ground already
completely clothed with an indigenous vegetation. We might
therefore conclude, a priori^ that the fiora of such an island as
St. Helena would be of an excessively ancient type, preserving
19
390
ISLAND LIFE.
[PabtIL
for lis in a slightly modified form exainplee of tlie vegetation
of tbo globe at the time when the island first rose above tbe
ocean. Let us see, then, what botanists tell ns of its character
and affinities.
The truly indigenons flowering plants are abont fifty in num-
ber, besides twenty-eix ferns. Forty of the former and ten of
the latter are absolutely peculiar to the island, and, ag Sir Josepli
Ilooker tells iia, " with scarcely an exception, cannot be i-egardcd
as very close specific allies of any other plnnta at all. Seven-
teen of them belong to peculiar gener,i, and of the others all
differ so markedly as species from their congeners that not one
comes under the category of being an insular form of a conti-
nental species." Tlie affinities of this flora are, Sir Joseph
Hooker thinks, mainly African and especially South African, aa
indicated by the presence of the genera Phylica, Pelargonium,
Mesoinbryantbeiuiun, Oteospermum, and Wableiibergia, which
are eminently cliaracteristie of eoutliern extratropical Africa.
Tbe sixteen ferns which are not peculiar are common either to
Africa, India, or America, a wide range sufficiently explained by
the dust -like spores of ferns, capable of being carried to un-
known distances by the wind, and the great stability of their
generic and specific forme, many of those found in tbe Miocene
deposits of Switzerland being hardly distinguishable from liv-
ing species. This shows tliat identity of species of ferns be-
tween St. Uelcna and distant countries does not necessarily im-
ply a recent origin.
Thu Helation of the SI. Ilehma dmiposit^.—Ia an elaborate
paper on the Composite,' Mr. Bentham gives ns some valuable
remarks on the affinities of the seven endemic species belonging
to the genera Commidendron, Melanodeudron, Petrobium, and
Pisiadia, which form so important a portion of the exieting
flora of St. Helena. He saya, "Although nearer to Africa than
to any other continent, those composite denizens wliicli bear ev-
idence of the greatest antiquity have their affinities, for the most
part, in South America, while the colonists of a more recent
character are South African. . . . Commidendron and Melano-
' "Noies oil the Clnsiiflcalioii. lllitoiT, mid Geogrnphknl Distribmion of Compo-
tits," Jtmraai »/ Iht I-Uiufai, S«riely. Vol, XIU., p. Ji03 (1878),
Chap. XIV.] ST. HELENA. 291
dendroQ are among the woody Asteroid forms exemplified in
the Andine Diplostephiam, and in the Australian Olearia. Pe-
trobium is one of three genera, remains of a group probably of
great antiquity, of wliich the two others are Podanthus ia Chili
and Astemma in the Andes. The Pisiadia is an endemic spe-
cies of a genus otherwise Mascarene or of Eastern Africa, pre-
senting a geographical connection analogous to that of the St.
Helena Melhanise ' with the Mascarene Trochetia."
Whenever such remote and singular cases of geographical af-
finity as the above are pointed out, the first impression is to im-
agine some mode by which a communication between tlie dis-
tant countries implicated might be effected; and this way of
viewing the problem is almost universally adopted, even by nat-
uralists. But if the principles laid down in this work and in
my "Geographical Distribution of Animals" are sound, such a
course is very unphilosophical. For, on the theory of evolution,
nothing can be more certain than that groups now broken up
and detached were once continuous, and that fragmentary groups
and isolated forms are but the relics of once wide-spread types,
which have been preserved in a few localities where the phys-
ical conditions were especially favorable, or where organic com-
petition was less severe. The true explanation of all such re-
mote geographical affinities is that they date back to a time
when the ancestral group of which they are the common de-
scendants had a wider or a different distribution ; and they no
more imply any closer connection between the distant countries
the allied forms now inhabit than does the existence of living
EquidiB in South Africa and extinct Equidse in the Pliocene
deposits of the Pampas imply a continent bridging the South
Atlantic to allow of their easy communication.
Concluding Remarks on St Helena, — The sketch we have now
given of the chief menribers of the indigenous fauna and flora
of St. Helena shows that by means of the knowledge we have
obtained of past changes in the physical history of the earth, and
of the various modes by which organisms are conveyed across
' The Melhnnioe comprise the two finest timber trees of St. Helena, now nlmost
extinct — the red-wood iind native ebonj.
292 ISLAND LIFE. [Part II.
the oceaD, all the more important facts becomo readily intelligi-
ble. We have here an island of small size and great antiquity,
very distant from every other land, and probably at no time
very much less distant from surrounding continents, which be-
came stocked by chance immigrants from other countries at
some remote epoch, and which has preserved many of their
more or less modified descendants to the present time. When
first visited by civilized man, it was in all probability far more
richly stocked with plants and animals, forming a kind of nat-
ural museum or vivarium in which ancient types, perhaps dating
back to the Miocene period, or even earlier, had been saved from
the destruction which has overtaken their allies on the great
continents. Unfortunately, many — we do not know how many —
of these forms have been exterminated by the carelessness and
improvidence of its civilized but ignorant rulers ; and it is only
by the extreme ruggedness and inaccessibility of its peaks and
crater-ridges that the scanty fragments have escaped by which
alone we are able to obtain a glimpse of this interesting chapter
in the life-history of our earth.
Chap. XV.] THE SANDWICH ISLANDS. 293
CHAPTER XV.
THE SANDWICH ISLANDS.
Position and Physical Features. — Zoolog}' of the Sandwich IsUnds. — Bird«. — Ke|>-
tiles. — Land Shells. — Insects. — Vegetation of the Sandwich Islands. — Peculiar
Features of the Hawaiian Flora. — Antiquity of the Hawaimn Fauna and Flora. —
Concluding Ohsenrations on the Fauna and Flora of the Sandwich It^Iands. — Gen-
eral Remarks on Oceanic Ishinds.
The Sandwich Islands are an extensive group of large islands
situated in the centre of the North Pacific, being 2350 miles
from the nearest part of the American coast — the Bay of San
Francisco — and about the same distance from the Marquesas and
the Samoa Islands to the south, and the Aleutian Islands a little
west of north. They are therefore wonderfully isolated in mid-
ocean, and are only connected with the other Pacific islands by
widely scattered coml reefs and atolls, the nearest of which, how-
ever, are six or seven hundred miles distant, and are all nearly des-
titute of animal or vegetable life. The group consists of seven
large inhabited islands besides four rocky islets; the largest,
Hawaii, being seventy miles across, and having an area of 3800
square miles — being somewhat larger than all the other islands
together. A better conception of this large island will be formed
by comparing it with Devonshire, with which it closely agrees
both in size and shape, though its enormous volcanic mountains
rise to nearly 14,000 feet. Three of the smaller islands are
each about the size of Hertfordshire or Bedfordshire, and the
Avhole group stretches from northwest to southeast for a distance
of about 350 miles. Though so extensive, the entire archipelago
is volcanic, and the largest island is rendered sterile and com-
paratively uninhabitable by its three active volcanoes and their
wide-spread deposits of lava.
The ocean depths by which these islands are separated from
the nearest continents are enormous. North, east, and south,
294
ISLAND LIFE.
UPABt U.
fionndingB have been obtained a little over or under 3000 fatli-
oms, and these profound deeps extend over a large part of the
North Pacific. We may be quite sure, tliei-efore, that the Sand-
wich Islands have during their wiiole existence been as com-
pletely severed from the great contiucuts as they are now ; but
on the west and south there is a possibility of more extensive
islands having existed, serving ns stepping-stones to the island
groups of the mid-Pacitic. This is indicated by a few widely
scattered coral islets, around which extend considenihie areas of
less depth, varying from 2oO to 1000 fathoms, and which mat/
therefore indicate the sites of submerged islands of considerable
extent. When we consider that cast of New Zealand and New
Caledonia all the larger and loftier islands are of volcanic origin,
_ki^
Chap. XV.]
THE SANDWICH ISLANDS.
20G
witli no traee of any ancient Btratificd rocks (except, perhaps, in
tlie Marquesas, where, according tu Jules Marcou, gniiiito and
gnoiiis are Baid to occur), it seenm probable that the ianunicrabic
coral reefs and atolls, which occur in groups on deeply Bnb-
nicrged banks, mark the silea of bygone vulfauic ielandu similar
I
to tliotio which now exist, bnt whidi, nflcr becoming extinct,
have been lowered op desti-oyed by denudation, and tinally, by
snbsidence of tlio earth's emat, have altogether diitappeartd, ex-
cept where their sites are indicated by the upward-growing coral
recfa. If this view is correct, we should give np all idea of there
ISLAND LIFE.
[Past II.
ever having been a Pacific contineut, but should look upon that
vast ocean as having from the i-einotest geological epoche been
the scat of volcanic forces, which from its profound depths have
gradnallj built up the islands which now dot its surface, as well
as many others which have suuk beneath its waves. The nnm-
ber of islands, as well as the total quantity of land stii'face, uiay
sometimes have been greater than it is now, and may thus have
facilitated the transfer of organisms from one group to another,
and, more rarely, even from the Aniericnn, Asiatic, or Australian
continent. Keeping these various facts and considerations in
view, we may now proceed to examine the fauna and flora of
the Sandwich Islands, and dlscQSs the special phenomena they
present.
Zoology of the Sanihcich Jifandif: Birds. — It need hardly be
said that indigenous manjiualiu arc quite unlcnown in the Sand-
wich Islands, the most interesting of the higher animals being
the birds, which arc tolerably nnmcrons and highly peculiar.
Many aquatic and wading birds wlucii range over tho whole Pa-
cific visit these islands, twenty-four epecies having been ob-
served ; but even of these five are peculiar — a coot, Fulka ala! ,-
H, inoor-hen, Oallin'ul.a Handvichenniii f & rail with rudimentary
wings, I'cnmtla viiUei ; and two ducks, Ana8 Wyvilllana and
Scmicla fiantlvichen»i«. The birds of jirey are also great wan-
derers. Four have been found in the islands — the short-eared
owl, Oliu imt'AyoiiM, which ranges over the greater part of the
globe, but ii< here said to resemble the variety found in Chili
and the Galapagos; the harn-o-wl, Stnx Jlamniea, oi a variety
common in t!io Pacilic; a peculiar sparrow-hawk, Aevipil^ir JIa-
xcaii ; and Uuteo sotitarius, a buzzard of a peculiar species, and
colored so as to resemble a hawk of the American enb-family
Polyborinte. It is to be noted that the genus Buteo abounds in
America, but is not found in the Pacific; and this fact, com-
bined with the remarkable coloration, renders it almost certain
that this peculiar species is of American origin.
Coming now to the Passeres, or true perehing-birds, we find
sixteen species, all peculiar, belonging to ten genera, all but one
of which are also peculiar. The following is a list of tlicse ex-
tremely interesting birds:
CuAP. XV.]
THE SANDWICH ISLANDS.
297
I.
MusciCAFiDA (Flycatchers).
1.
Chasiempis Sandvichensis,
Ma
Phceornis obscura.
[r.
Melipuaoidjb (Honeysackers).
3.
Mohoa nobilis.
4.
" braccata.
r».
** apicalis.
6.
Chatoptila angusti}*luma.
III. Drepanididje.
7.
Drepanis coccinea.
8.
** rosea.
9.
** Jlava.
10.
*^ tanguinea.
Drepanididfe — Continued.
1 1. Hendgnathus olivaceus,
12. ** obacunu.
13. <' /aici(f««.
14. Lorops coccinea,
15. ** Aurea.
] 6. Loxioides bailloni,
1 7. Psittirottra psittacea,
18. Fringilla anna (recently de-
scribed, perhaps belongs
also to this group).
IV. CoRviDJE (Crows).
19. Cor V us Hawaiensis,
Taking the above in the order here given, we have, first, two
peculiar genera of flycatchers, a family confined to the Old
World, but extending over the Pacific as far as the Marquesas
Islands. Next we have two peculiar genera (with four species)
of honeysuckers, a family confined to the Australian region, and
also ranging over all the Pacific islands to the Marquesas. We
now come to the most important group of birds in the Sandwich
Islands, comprising five peculiar genera, and eleven or twelve
species, which are believed to form a peculiar family allied to
the Oriental flower-peckers (Diceidse), and perhaps remotely to
the American greenlets (Vireonidse) or tanagers (Tanagridae).
They possess singularly varied beaks, some having this organ
much thickened like those of finches, to which family some of
them have been supposed to belong. In any case, they form a
most peculiar group, and cannot be associated with any other
known birds. The last species, and the only one not belonging
to a peculiar genus, is the Hawaiian crow, belonging to the al-
most universally distributed genus Corvus.
On the whole, the affinities of these birds are, as might be ex-
pected, chiefly with Australia and the Pacific Islands; but they
exhibit in the buzzard, one of the owls, and perhaps in some of
the Diepanididffi, slight indications of very rare or very remote
communication with America. The amount of speciality is, how-
ever, wonderful, far exceeding that of any other islands ; the
only approach to it being made by New 2^aland and Madagas-
car, which have a much more varied bird fauna and a smaller
ISUND UFE.
tPAaxIL
proportionate number of peculiar genera. These fuels undoubt-
edly indicate an iniracnsQ antiquity for this group of islands, ov
the vicinity of some very ancient land (now submerged), from
wliich some portion of their peculiar fauna might be derived.
lieptlUs. — The only other vertebrate animals are two lizards.
One of these ia a very wide-spread species, Ahltfpliarua pacilo-
pleurus, Buid by Dr. (riinther to be found in Timor, Australia,
the Samoa Islands, and the Sandwicli Islands. It seems hai-dly
likely tliat such a i-ange can be due to natural causes. The
other is said to form a peculiar genus of geckoes, but both its
locality and aflinitios appear to bo somewhat doubtful.
Laiul SluslU. — The only other group of animals which has
been carefully studied, and which presents features of esjiecial in-
terest, are the land shells. These are very numerous, about thirty
genera and between three and four hundred species having been
described; and it is remarkable that this single group contains
as many species of land shells as all the other Pulynesian islands
from tlie Felow Islands and Samoa to the Marquesas. All the
species are peculiar, and about throe fourths of the whole belong
to peculiar genera, fourteen of which constitute the sub-family
Achatiuellinie, entirely contined to tliis group of islands and con-
stituting its most distinguishing feature. Thirteen genera (com-
prising sixty -four species) are found also in the other Polynesian
islands, but three genera of Auriculidie (Pleootroma, Pedipes,
and Elanneria) are not found in the Piicitie, but inhabit — the
former genus Anstralia, China, Bourbon, and Cuba, the two lat-
ter the West Indian Islands. Another remarkable peculiarity
of these islands is the small number of Operculata, which are
represented by only one genua and live species, while the other
Pacilic islands have twenty genera and 115 species, or more
than half the number of the Inoperculata. Tliis difference is
LKO remarkable that it is worth stating in a comparative form :
laoptrciilnl*. OparcnlKU. AaricnlidiK
Snndwicli Mnndi iVi-l T, 9
Ucal of I'ndlic island* .. SOO IIS 16
When we remember that in the West Indian Islands the
Operculata abound in a greater proportion than even in the
IZZI
Chap. XV.] THE SANDWICH ISLANDS. 299
stone, which is plentiful in both these areas, is especially favor-
able to them, while the purely volcanic rocks are especially un-
favorable. The other peculiarities of the Sandwich Islands,
however, such as the enormous preponderance of the strictly
endemic Achatinellinse, and the presence of genera which occur
elsewhere only beyond the Pacific area in various parts of the
great continents, undoubtedly point to a very remote origin, at a
time when the distribution of many of the groups of Mollusca
was very different from that which now prevails.
A very interesting feature of tlie Sandwich group is the ex-
tent to which the species and even the genera are confined to
separate islands. Thus the genera Carelia and Catinella, with
eight species, are peculiar to the island of Kaui ; Bulimella,
Apex, Frickella, and Blauneria to Oahu; Perdicella to Maui;
and Eburnella to Lanai. The Rev. John T. Gulick, who has
made a special study of the Achatinellinse, informs us that the
average range of the species in this sub-family is five or six
miles, while some are restricted to but one or two square miles,
and only very few have the range of a whole island. Each val-
ley, and often each side of a valley, and sometimes even every
ridge and peak, possesses its peculiar species.* The island of
Oahu, in which the capital is situated, has furnished about half
the species already known. This is partly due to its being more
forest-clad, but also, no doubt, in part to its being better ex-
plored ; so that, notwithstanding the exceptional riches of the
group, we have no reason to suppose that there are not many
more species to be found in the less explored islands. Mr. Gulick
tells us that the forest region that covers one of the mountain-
ranges of Oahu is about forty miles in length, and five or six
miles in width, yet this small territory furnishes about 175 spe-
cies of Achatinellinae, represented by 700 or 800 varieties. The
most important peculiar genus, not belonging to the Achatinella
group, is Carelia, with six species and several named varieties,
all peculiar to Kaui, the most westerly of the large islands. This
would seem to show that the small islets sti*etching westward,
* Journal of the LinrKran Society^ 1873, p. 406, '* On Diversity of Evolution
ander one Set of External Conditions." Proceedings of the Zoological Society of
London^ 1873, p. 80, " On the Classification of the Achatinellinn.*'
800 ISLAND LIFE. [I'Adt II.
and Bittiatcd on an extensive bank with less tlian a thotieand
fathoms of water over it, may indicate the position of a large
submerged island whence some portion of the Sandwich Island
fauna was derived.
Insects. — Unfortunately we have as yet no 6uch knowledge
of the insects of these islands as we possess in tlic ease of the
Azores and St. Helena, but some considerable collections have
been sent over by Mr. T. Blackburn, now resident there, and we
may therefore soon possess fuller and more accurate information,
Although insects are said to be very scarce, yet all the chief
tribes of Coleoptera appear to be represented, though as yet by
very few species. These appear to be, for the most part, peculiar,
but to have wide-spread affinities. The majority, as might be ex-
pected, are allied to Polynesian, Australian, or Malayan forms;
some few are South American (perhaps introduced), while others
show north temperate affinities. There are several new genera,
and one peculiar group of six species is said to form a new family
allied to the Anthribidis. A new genus of Lucanidfe is said to
be allied to a Chilian genus. If we consider the greater facilities
of insects for dispersal when compared with birds or land shells,
the characteristics of the insect fauna, so far as yet known, are
sufficiently in harmony with the amount of speciality and isola-
tion presented by the latter groups.
Vetfdation of the Sandwich Islands. — The flora of these isl-
ands is in many respects so peculiar and remarkable, and so well
supplements the information derived from its interesting but
scanty fauna, that a brief account of its more striking features
will not be out of place; and wo fortunately have a pretty full
knowledge of it, owing to the researches of the American bota-
nist Horace Mann, and of Dr. Pickering, who accompanied the
United States Exploring Expedition.
Considering their extreme isolation, their uniform volcanic
soil, and the large proportion of the chief island which consists
of barren lava-flelds, the flora of the Sandwich Islands is ex-
tremely rich, consisting, so far as at present known, of 554 spe-
cies of flowering plants and 135 ferns. This is considerably
riclier than the Azores (439 Phanerogams and 39 ferns'), which,
though less extensive, are far better known, or than the Gain-
Chap. XV.] THE SANDWICH ISLANDS. 801
pagos (332 Phanerogams), which are more strictly comparable,
being equally volcanic, while their somewhat smaller area may
perhaps be compensated by their proximity to the American
continent. Even New Zealand, with more than twenty times
the area of the Sandwich group, whose soil and climate are
much more varied, and whose botany has been thoroughly ex-
plored, has not double the number of flowering plants (935 spe-
cies), while in ferns it is barely equal.
Pecxdiar Feaiures of the Flora. — This rich insular flora is
wonderfully peculiar, for if we deduct 69 species, which are
believed to have been introduced by man, there remain 620 spe-
cies, of which 377, or more than three fifths, are quite peculiar
to the islands. There are no less than 39 peculiar genera out of
a total of 253, and these 39 genera comprise 153 species, so that
the most isolated forms are those which most abound and thus
give a special character to the flora. Besides these peculiar
types, several genera of wide range are here represented by
highly peculiar species. Such are Lobelia, the Hawaiian species
of which are woody shrubs from six to twenty feet high, one
even being a tree reaching a height of forty feet. Shrubby
geraniums fifteen feet high grow as epiphytes on forest trees, as
do some Yacciuiums and Epacrids. Violets and plantains also
form tall shrubby plants, and there are many strange arbores-
cent Compositse, as in other oceanic islands.
The affinities of the flora generally are very wide. Although
there are many Polynesian groups, yet Australian, New Zealand,
and American forms arc equally represented. Dr. Pickering
notes the total absence of a large number of families found in
Southern Polynesia, such as Dilleniacese, Anonaceae, Olacacese,
Aurantiaceae, Guttiferae, Malpighiacese, Meliaceae, Combretacefle,
Ehizophoraccae, Melastomaceee, Passifloraceae, Cunoniaceae, Jas-
minaceae, Acanthaceae, Myristicaceae, Casuaraceae, Scitamineae,
and Aracae, as well as the genera Clerodendrum, Ficus, and epi-
dcndric orchids. Australian aflinities are shown by the genera
Exocarpus, Cyathodes, Melicope, Pittosporum, and by a phyl-
lodinous Acacia. New 2^aland is represented by Ascarina, Co-
prosma, Acaena, and several Cyperaceae ; while America is rep-
resented by the genera Nama, Gunnera, Phyllostegia, Sisyrin-
302
ISLASD LIFE.
[Pabt II.
diium, and by a red-flowered Rnbus and a yellow-flowered Sanic-
u!a allied to Oregon species.
There is no true alpiae flora on the higher enmmits, but sev-
ei-al of the temperate forms extend tu a great elevntiuii. Thus
Mr. Pickering records Vaccinium, Ranmiculua, Sileiie, Gnapha-
Huni, and Geranium as occnmng above ten lhonB.iiid feet ele-
vation; while Viola, Drosera, Actenn, Lobelia, Edwardsia, Do-
donsea, Lycopodium, and many CorapositEe range above six
thousand feet. Vaccinium and Silene are veiy interesting, as
they are peculiar to the north temperate zone, except one Sileny
in South Africa.
The proportionate abundance of the different families in this
interesting flora is as follows:
1. Compodlffi 47ii>acies.
2. Cjiierflcea! 3D "
8. LobeliaceiB 85 "
i. RuluceB! 83 "
5. Lnbiotie 27 "
6. LcgnminiwB SO "
7. Huweae 17 "
8. Caryo]iliyllaceu 14 "
9. GcsiioriiicoK. 1* "
10. UrticaccK 13 "
II. Piperacea
la. CollVQlvulttfOtt! ..
13. Miilviicca
II. Amnrnntncon.-.
IS. AmliaceRi
18. Violneo*
IT. riiionimracett,..
IS. MvflnreiB
IS), GiMHleninceic
'2t>. Th) melauen
Four other orders — Geraniaceffi, Riiamnacete, RosacetP, and
CncurbitaeeiE — have Ave species each ; and among the more im-
portant oi'dera which have less than live species each are Ranun-
cnlaceie, Eiicaceae, Prinmlacese, Polygonaccte, Orchidaceie, and
Juncaceffi. In the above enumeration the grasses (Graminacete)
are omitted, as they were not described at the time Mr. Mann's
article was written, Tlie most remarkable feature here is the
great abundance of Lobeliaccffi, a character of the flora which is
probably unique; while the superiority of Labiatw to Legnnii-
noBie and the scarcity of Rosacese and Orcliidaccfc are also very
nnusual. Composites, as in most temperate floras, stand at the
head of the list, and as these have been carefully studied by Mr.
Bcntham, it will be interesting to note the afSnitics which they
indicate. Omitting four genera and species wliieli are cosmo-
politan, and have no doubt entered with civilized man, there re-
Chap. XV.] THE SANDWICH ISLANDS. 303
main twelve genera and forty-fonr species of Composit© in the
islands. All the species are peculiar, as are six of the genera ;
and in another genus, Coreopsis, the six species form a peculiar
named section or sub-genus, Campylotheca ; while the genus
Lipocheeta, with ten species, is only known elsewhere in the
Galapagos, where a single species occurs. We may therefore
consider that eight out of the twelve genera of Hawaiian Com-
positsB are really confined to the archipelago. The relations of
the genera are thus given by Mr. Bentham :
No. of Species. External Relations of the Species.
Lflgenopliora 1 Witli the Old World and Extmtropical America.
Aster 1 American and Extratropical Old World.
Tetramolubium G South Extratropical American.
Vittadinia 1 South Extratropical American and Australian.
Campylotheca (s.g.). . G With the Tropical American and very few Old World
species of Coreopsis and Bidens.
Bidens 1 The IVopicnl American species.
Lipochaeta 10 American Wedelioidos and Helianthioidse.
Argyroxiphium 2 With Madica of the Mexican region.
Wilkesia 1 With Madieie of the Mexican region.
Dubantin 3 Distantly with Madieas and Galinsogen of the Mexi-
can region.
Baillardia 11 W^ith Riiillnrdella of the Mexican region.
Hesperomannin 1 With Stifftin and Wunderlichia of the Brasilian re-
gion.
The great preponderance of American relations of the Com-
positffi, as above indicated, is very interesting and suggestive.
It is here that we meet with some of the most isolated and re-
markable forms, implying great antiquity ; and when we con-
sider the enormous extent and world-wide distribution of this
order (comprising ten thousand species), its distinctness from all
others, the great specialization of its flowers to attract insects,
and of its seeds for dispersal by wind and other means, we can
hardly doubt that its origin dates back to a very remote epoch.
We may therefore look upon the Compositae as representing the
most ancient portion of the existing flora of the Sandwich Isl-
ands, carrying us back to a very remote period when the facili-
ties for communication with America were greater than they
are now. This may be indicated by the two deep submarine
banks in the North Pacific, between the Sandwich Islands and
304
ISLAND LIFE.
tir.
San Francisco, wliicb, from an ocean-floor nearly 3000 fatboitis
deep, rise np to within a few hundred fathoms of the snrface,
and eeeni to indicate the subsidence of two islands, each about
as large as Hawaii. The plants of north tempemte affinity may-
be nearly as old, but these may have been derived from North-
ern Asia by way of Japan and the extensive line of elioala
which run nortliweatwai'd from the Sandwicli Islands as shown
on our uiap. Those which exhibit Polynesian or Australian
affinities, consisting, for the most part, of less highly modified
species usually of the same genera, may have had their origin at
II later, though still somewhat remote, period, when large islands,
indicated by the extensive shoals to the south and southwest,
offered facilities for the transmission of plants from the tropical
portions of the Pacific Ocean.
Antiquity I'f the Hawaiian Fauna and Flora. — The great an-
tiquity implied by the peculiarities of the fauna and tlors, no
less than by the geographical conditions and surroundings, of
this group will enable us to account for another peculiarity of
its flora— the absence of so many families found in other Pacific
islands. For the earliest immigrants would soon occupy much
of the snrface, and become specially modified in accordance with
the conditions of the locality, and these would serve ns a bar-
rier against the intrusion of many forms which at a later period
Bpi-ead over Polynesia. The extreme remoteness of the islands,
and the probability that they have always been more isolated
than those of the Central Pacific, would also necessarily result
in an imperfect and fragmentary representation of the flom of
sun'ounding lands.
Vonchuliiuj Observations on tfie Fauna nud Flora ofthe&iml'
wich Inlands. — The indicationa thus aflforded by a study of the
flora seem to accord well with what we know of the fauna of
the islands. Plants, having so much greater facilities for disper-
sal than animals, and also having greater specific longevity and
greater powers of endurance under adverse conditions, ciihibit
in a considerable degree the influence of the primitive slate of
the islands and their surroundings; while members of the ani-
mal world, passing across the sea with greater difficulty, and
subject to extermination by a variety of adverse conditions, re-
Chap. XV.] OCEANIC ISLANDS. 305
tain much more of the impress of a recent state of things, with,
perhaps, here and there an indication of that ancient approacli
to America so clearly shown in the Compositse and some other
portions of the flora.
General Remarlcs on Oceanic Inlands, — We have now reviewed
the main features presented by the assemblages of organic forms
which characterize the more important and best-known of the
oceanic islands. They all agree in the total absence of indig-
enous mammalia and amphibia ; while their reptiles, when they
possess any, do not exhibit indications of extreme isolation and
antiquity. Their birds and insects present just that amount of
specialization and diversity from continental forms which may be
best explained by the known means of dispei^sal acting through
long periods ; their land shells indicate greater isolation, owing
to their admittedly less effective means of conveyance across
the ocean ; while their plants show most clearly the effects of
those changes of conditions which we have reason to believe
liave occurred during the Tertiary epoch, and preserve to us in
highly specialized and archaic forms some record of the prime-
val immigration by which the islands were originally clothed
with vegetation. But in every case the series of forms of life
in these islands is scanty and imperfect as compared with far
less favorable continental areas, and no one of them presents
tuicli an assemblage of animals or plants as we always find in an
island which we know has once formed part of a continent.
It is still more important to note that none of these oceanic
archipelagoes present us with a single type which we may sup-
pose to have been preserved from Mesozoic times ; and this fa'ct,
taken in connection with the volcanic or coralline origin of all
of them, powerfully enforces the conclusion at which we have
arrived in the earlier portion of this volume, that during the
whole period of geologic time, as indicated by the fossiliferous
rocks, our continents and oceans have, speaking broadly, been
permanent features of our earth's surface. For had it been oth-
erwise— had sea and land changed place repeatedly, as was once
supposed ; had our deepest oceans been the seat of great conti-
nents, while the site of our present continents was occupied by
an oceanic abyss — is it possible to imagine that no fragments
20
306 ISLAND LIFE. [Pabt II.
of Bucli continents would remain in the present oceans, bringing
down to us some of their ancient forms of life preserved with
but little change ? The correlative facts that the islands of our
great oceans are all volcanic (or coralline built, probably, upon
degraded and submerged volcanic islands), and that their pro-
ductions are all more or less clearly related to the existing in-
habitants of the nearest continents, are hardly consistent with
any other theory than the permanence of oceanic and continental
areas.
We may here refer to the one apparent exception, which,
however, lends additional force to the argument. New Zealand
is sometimes classed as an oceanic island, but it is not so really ;
and we shall discuss its peculiarities and probable origin further
on.
Chap. XVI.] TUE BRITISH ISLES. 307
CHAPTER XVI.
CONTINENTAL ISLANDS OF RECENT ORIGIN: GREAT BRITAIN.
Characteristic Features of Recent Continental Islands. — Recent Physical Changes
of tlie British Isles. — Proofs of Former Elevation. — Submerged Forests. — Buried
River Channels. — Time of Last Union with the Continent. — Why Britain is Poor
in Species. — Peculiar British Birds. — Fresh-water Fishes. — Cause of Great Spe-
ciality in Fishes. — Peculiar Biitish Insects. — Lepidoptera Confined to the British
Isles. — Peculiarities of the Isle of Man Lepidoptera. — Coleoptera Confhied to
the British Isles. — Trichoptera Peculiar to the British Isles. — Land and Fresh-
water Shells. — Peculiarities of the British Flora. — Peculiarities of the Irish Flora.
— Peculiar British Mosses and Hepaticie. — Concluding Remarks on the Peculiari-
ties of the British Fauna and Flora.
We now proceed to examine those islands which are the very
reverse of the " oceanic " class, being fragments of continents or
of larger islands from which they have been separated by sub-
sidence of the intervening land at a period which, geologically,
must be considered recent. Such islands are always still con-
nected with their parent land by a shallow sea, usually, indeed,
not exceeding a hundred fathoms deep; they always possess
mammalia and reptiles either wholly or in large proportion
identical with those of the mainland ; while their entire flora
and fauna are characterized either by the total absence or com-
parative scarcity of those endemic or peculiar species and genera
which are so striking a feature of all oceanic islands. Such isl-
ands wull, of course, differ from each other in size, in antiquity,
and in the richness of their respected faunas, as well as in their
distance from the parent land and the facilities for intercom-
munication with it; and these divereities of conditions will man-
ifest themselves in the greater or less amount of speciality of
their animal productions.
This speciality, when it exists, may have been brought about
in two ways. A species or even a genus may on a continent
have a very limited area of distribution, and this area may be
ISLAND LIFE.
[Part 11.
wholly, or iilinoat wholly, contained in t!ie sepamteJ portion op
island, to wliidi it will hencefortJi be peculiar. Even when the
area occupied by a species is pretty equally divided at tho time
of eeparatioii between the island and the continent, it may hop-
pen that it will become extinct on the latter, while it may eur-
vive on the former, because the limited number of individuals
after division may be unable to maintain themselves against the
severer competition or more contrasted climate of the coutinent,
while they may flourish under the more favorable insular condi-
tions. On the other hand, when a species continues to exist in
both areas, it may on the island be subjected to some modifica-
tions by the altered conditions, and may thus come to present
chamcters which differentiate it from its continental allies and
constitute it a new species. We shall in the couree of our sur-
vey meet with eases illustrative of both these processes.
The best examples of recent continental islands are Great
Britain and Ireland, Japan, Formosa, and the larger Malay isl-
ands, especially Borneo, Java, and Celebes ; and as each of these
presents special features of interest, wo will give a short outline
of their zoology and past liistory in relation to that of the con-
tinents from wliieh they have recently been separated, com-
mencing with our own islands, to which the present chapter will
bo devoted.
J^ecent Phym-al Changes in tJus Bntl«h Idf-8. — Great Britain
is perhaps the most typical example of a large and recent con-
tinental island now to be found upon the globe. It is joined to
the continent by a shallow bank which extends from Dtninark
to the Bay of Biscay, tlie lOO-fathom line from these c\tremc
points receding from the coasts so as to include the whole of
the British Isles and aboot fifty miles beyond them to the west-
wai-d. (See map.) Beyond this line the sea deepens rapidly to
the 600 and 1000 fathom lines, the distance between 100 and
1000 fathoms being fram twenty to fifty miles, except where
there is a grout outward curve to include the Porcupine Bank,
170 miles west of Galwny, and to the northwest of Caithness,
where a narrow ridge less than 500 fathoms bolow the surface
joins the extensive bank under 300 fathoms, on which are situ-
ated the Faroe Islands and Iceland, and which stretches across
CHif.STL] THE BRITISH 18LE8. SOft
to Greenlnnd. In the Nortli Chauuel between Ii-elaiid and Scot-
liind, and in t!ic Minch between tlie onter Ilebndea and Skye,
are a series of ludl.uvs in tlie Sfu-bottmn from lOU tu IHO f.itliotns
'i'li« liglit tint indicniGs ■ depdi of Ust (lian 100 fiithoms.
The fiKurci thaw liie depth in ritthnm*.
Tlie iian'uiv cliatinel beliveen Noin'n/ nnJ Denmnvli is 2180 fvcl Jvcp.
deep. Tliese correspond exactly to the points between tlie op-
posing htgtdande where the greatest accnmulations of ice wonid
necessarily occur during the glacial cpoclt. and they may well
310
ISLAND LIFE.
[PARTlr.
be termed Eiibmariiie lakes, of exactly tlie same nature as those
wliicli occur in similar positiung on land.
Proof 8 nf Former EUvation—Sulmerifed Forests. — Wliat ren-
ders Britain particultirly ingtriictivo as an example of a recent
continentnl island is the amount of direct evidence that exists, of
several distinct kinds, showing that tiic land has been sufficiently
elevated (ov the sea depressed) to unite it witL the continent — ■
and tliis at a very recent period. The first class of evidence ia
the existence, all round onr coasts, of the remains of submarine
forests often extending far below the present low-water mark.
Such arc the submerged forests near Tor<i»ay in Devonshire,
and near Falmouth in Cornwall, both containing stumps of trees
in tlieir natural position rooted in the soil, with deposits of peat,
brnncJies, and nnts, and often with remains of insects and other
land animalB. These occur in very different conditions and sit-
uations, and some have been explained by changes in the height
of the tide, or by pebble banks shutting out tlie tidal waters
from estuaries; but there are nnmerous examples to which such
hypotheses cannot apply, and which can only be explained by an
actual subsidence of tlie land (or rise of the sea-level) since the
trees grew.
We eannot give a better idea of those forests than by quoting
the following account by Mr. I'engclly of a visit to one which
liad been exposed by a violent storm on the coast of Devonshire,
at Blackpool, near Dartmouth ;
•'We were so fortunate as to reach the beach nt spring-tide
low water, and to find, admirably exposed, by far the finest ex-
ample of a submerged forest which I have ever seen. It occu-
pied a rectangular area, extending from the small river or stream
at the western end of tlie inlet about one furlong eastward,
and from the low-water lino thirty yards np the strand. The
lower or seawaivl portion of the forest area, ocenpying about
two thirds of Its entire breadth, eonsisted of a brownish drab-
colored clay, which was crowded with vegetable dubris, such ee
small twigs, leaves, and nnts. Tliero were also numerous pros-
trate trunks and branches of trees, lying partly eml)edded in the
clay, williout anything like a prevalent direction. The trunks
varied from six inclics to uiiivurde of two feet in iliameter.
Chap. XVI.] TUB BRITISH ISLES. 811
Much of the wood was found to have a reddish or bright-phik
hue when fresh surfaces were exposed. Some of it, as well as
many of the twigs, had almost become a sort of ligneous pulp ;
while other examples were firm, and gave a sharp crackling
sound on being broken. Several large stumps projected above
the clay in a vertical direction, and sent roots and rootlets into
the soil in all directions and to considerable distances. It was
obvious that the movement by which the submergence was ef-
fected had been so uniform as not to destroy the approximate
horizontality of the old forest ground. One fine example was
noted of a large prostrate trunk having its roots still attached,
some of them sticking up above the clay, while others were buried
in it. Hazel-nuts were extremely abundant — some entire, others
broken, and some obviously gnawed. ... It has been stated that
the forest area reached the spring-tide low-water line ; hence as
the greatest tidal range on this coast amounts to eighteen feet,
we are warranted in inferring that the subsidence amounted to
eighteen feet as a minimum, even if we suppose that some of
the trees grew in a soil the surface of which was not above the
level of high water. There is satisfactory evidence that in Tor-
bay it was not less than forty feet, and that in Falmouth harbor
it amounted to at least sixty-seven feet."*
On the coast of the Bristol Channel similar deposits occur, as
well as along much of the coast of Wales and in Holyhead har-
bor. It is believed by geologists that the whole Bristol Channel
was, at a comparatively recent period, an extensive plain, through
which flowed the river Severn ; for, in addition to the evidence
of submerged forests, there are on the coast of Glamorganshire
numerous caves and fissures in the face of high sea-cliffs, in one
of which no less than a thousand antlere of the reindeer were
found, the remains of animals which had been devoured there
by bears and hyenas — facts wliich can only be explained by the
existence of some extent of dry land stretching seaward from
the present cliffs, but since submerged and washed away. This
plain may liave continued down to very recent times, since the
whole of the Bristol Channel to beyond Lundy Island is under
• Geological Maf/azine, 1870, p. 165.
313
ISLAND LIFE.
[l'*m 11.
twetitj'-fivc fiitlioms deep. In tlio Eiist of Enghnd wc liavc a
similar forest-bed at Cromer in Norfolk ; and in the North of
Holland an old land sarface has been fonnd fifty-six feet helow
liigli-walcr mark.
Bui'ifd liiver Channel. — Still more remarkable are the buried
river channels whieh Im%'e been ti'sced oti many parts of our
coasts. In order to-facilitato tlie Btiidy of the glacial deposits
of Scotland, Dr. James Croll obtained the details of about two
hundred and fifty bores put down in all parts of the mining dis-
tricts of Scotland for the purpose of discovering minerals.' These
revealed the interesting fact that there arc ancient valleys and
river channels at depths of from lOO to 200 feet below the pres-
ent sea-level. TJiese old rivers sometimes run in quite different
directions from the present lines of drainage, connecting what
are now distinct valleys ; and they are so completely filled np
and hidden by boulder clay, drift, and sands that there is no in-
dication of their presence on the surface, which often consists of
mounds or low bills more than 100 feet high. One of these old
valleys connects the Clyde near Dumbarton with the Forth at
. Grangemouth, and appears to have contained two streams flow-
ing in opposite directions from a watcr-sbcd abont midway at
Kilsith. At Grangemouth the old channel is 260 feet below
the sea-level. The water-shed at Kilsith is now 160 feet above
the sea — the old valley-bottom being 120 feet deep, or 40 feet
above the sea. In some ])Iace6 the old valley was a ravine witli
precipitous rocky walls, which have been found in mining cxcsxQ
vations, Br. Geikie, who has himself discovered many t
buried valleys, is of opinion that "they nnqucstionabjy belongf
to the period of the boulder clay."
We have here a clear proof that when these rivers were form-
ed the land must have stood in relation to the sea at ha»t 260
feet higlier than it does now, and probably much more ; and this
is sufficient to join England to the continent. Supporting this
evidence, we have fresh-water or littoral sheila found at great
depths off our coasts. Mr. (iodwin Austen recoi-da the dredging-
up of a fi-esh-water shell {Unio pietorutn) oS the mouth of the
' Trantarlioni n/rA(. RHnlmrs/, C^rgiml Sxritls. Vol. I,
Chap. XVI.] THE BRITISH ISLES. 813
English Channel between the 50-fathom and lOO-fathom lines,
while in the same locality gravel banks with littoral shells now lie
under sixty or seventy fathoms water/ More recently Mr. G wyn
Jeffreys has recorded the discovery of eight species of fossil arc-
tic shells off the Shetland Isles in about ninety fathoms water,
all being characteristic shallow-water species, so that their asso-
ciation at this great depth is a distinct indication of considerable
subsidence.'
Time of Last Union with the Continent. — The period when
this last union with the continent took place was comparatively
recent, as shown by the identity of the shells with living species,
and the fact that the buried river channels are all covered with
clays and gravels of the glacial period, of such a character as to
indicate that most of them were deposited above the sea-level.
From these and various other indications geologists are all agreed
that the last continental period, as it is called, was subsequent to
tlic greatest development of the ice, but probably before the
cold epoch had wholly passed away. But if so recent, we should
naturally expect our land still to show an almost perfect com-
munity with the adjacent parts of the continent in its natural
productions ; and such is found to be the case. All the higher
and more perfectly organized animals are, with but few excep-
tions, identical with those of France and Germany ; while the
few species still considered to be peculiar may be accounted for
either by an original local distribution, by preservation here ow-
ing to favorable insular conditions, or by slight modifications
having been caused by these conditions resulting in a local race,
sub-species, or species.
Why Bintain is Poor in Species. — The former union of our
islands with the continent is not, however, the only recent change
they have undergone. There is equally good evidence that a
considerable portion, if not the entire area, had been submerged
to a depth of nearly 2000 feet (see Chap. IX., p. 166), at which
time only what are now the highest mountains would remain as
groups of rocky islets. This submersion must have destroyed
» Quarter!^ .Journal of Geological Society^ 1 8oO, p. 9G.
• ** British Association Report," Dundee, 18C7, p. 431.
8U
ISLASD LIFE.
[PiBTlL
the gi-eater part of the life of our country; and ns it certainly
occurred during the latter part of the glacial epoch, the siibse-
queut elevation and union with the continent cannot have been
of very long duration, and this fact must have had an important
bearing on the character of the existing fauna and flora of Brit-
ain. We know that just before and during the glacial period
we posseesed a fauna ahnost or quite identical with that of ad-
jacent parts of the continent, and e()iially rich in species. The
submergence destroyed this fauna ; and the peniianent change
of climato on the passing-away of the glacial conditions appears
to have led to the extinction or migration of many species in
the adjacent continental areas, where they were succeeded by the
assemblage of animals now occupying Central Europe. Wlicn
England became continental, these entered our country; hut
sufficient time does not seem to have elapsed for the migration to
have been completed before subsidence again occurred, cutting
off the further influx of purely terrestrial animals, and leaving
us withont the number of species which our favorable climato
and varied surface entitle na to.
To this cause wo must impute our comparative poverty in
mammalia and reptiles — more marked in the latter than thefoi"-
mer, owing to their lower vital activity and smaller powers of
dispersal. Germany, for example, possesses nearly ninety species
of land mammalia, and even Scandiuavia about sixty, while Brit-
ain has only forty, and Ireland only twenty-two. The depth of
tho Irish Sea being somewhat greater than that of the German
Ocean, the connecting land would thus probably be of small ex-
tent and of lees duration, thus offering an additional barrier to
migration, whence has arisen tho comparative zoological poverty
of Ireland. This poverty attains its maximum in the reptiles, aa
sliown by the following fignres:
Bulgiiim has 22 epecics of reptiles nnd amjihibi.i.
Where the power of flight existed, and thns the period of n
gratiou was prolonged, tho difference is leas marked; so that
Ireland has seven bats to twelve in Britain, and about 110 as
a":iinst 130 land birds.
OiiAP.XVI.J THE BRITISH ISLES. 315
Plants, which have considerable facilities for passing over the
sea, are somewhat intermediate in proportionate numbers, there
being about 970 flowering plants and ferns in Ireland to 1425
in Great Britain — or almost exactly two thirds, a proportion
intermediate between that presented by the birds and the mam-
malia.
Peculiar Brituh Birds, — Among our native mammalia, rep-
tiles, and amphibia, it is the opinion of the best authorities that
we possess neither a distinct species nor distinguishable variety.
In birds, however, the case is diflEerent, since some of our spe-
cies, in particular our coal-tit {Parus ater) and long-tailed tit
{Parus caudatm) present well-marked diflferences of color as
compared with continental specimens; and in Mr. Dresser's
work on the " Birds of Europe " they are considered to be dis-
tinct species; while Professor Newton, in his new edition of
Yarrell's " British Birds," does not consider the difference to be
suflieiently great or sufficiently constant to warrant this, and
tlierefore classes them as insular races of the continental species.
We have, however, one undoubted case of a bird peculiar to the
British Isles in the red grouse {Lagopus Scoticms)^ which abounds
in Scotland, Ireland, the North of England, and Wales, and is
very distinct from any continental species, though closely allied
to the willow-grouse of Scandinavia. This latter species resem-
bles it considerably in its summer plumage, but becomes pure
white in winter; whereas our species retains its dark plumage
throughout the year, becoming even darker in winter than in
summer. We have here, therefore, a most interesting example
of an insular form in our own country ; but it is difficult to de-
termine how it originated- On the one hand, it may be an old
continental species which during the glacial epoch found a ref-
uge here when driven from its native haunts by the advancing
ice ; or, on the other hand, it may be a descendant of the North-
ern willow-grouse, which has lost its power of turning white in
winter owing to its long residence in the lowlands of an isl-
and where there is little permanent snow, and where assimila-
tion in color to the heather among which it lurks is at all
times its best protection. In either case it is equally interest-
ing, as the one large and handsome bird which is peculiar to
316
ISLAND LIFE.
[Haf
our islands, iiotwitiistanduig their recent sepnmtion fi'oiii tlie
continent.
The following is a list of birds now held to be peculiar to the
British Isles :
t. Parut Si
oflhe
M. .Closely allieJ to P.
2. " roiea Allied W P. raiirfadaof iliecouiinem.
3. Lajopnu SH)tiBtu...Ai\\vd Ut L. a^Wof Sonnilmnvm, but VGI7 dint i net.
Freeh-waier Fishes. — Altlioiigli the productions of fresli wa-
ters have generally, as Mr. Darwin has shown, a wide range,
fishes appear to form an exception, many of them being ex-
tremely liinited in distribution. Some are confined to particu-
lar river valleys or even to single rivers, others inhabit the lakes
of a limited district only, while Bomo are eoniiued to single lakes
— often of small area — and these latter offer examples of the
most restricted distribntion of any organisms whatever. Cases
of this kind are found in our own islands, and deserve our es-
jiQcial attention. It has long been known that some of our lakes
possessed peculiar siiecies of trout and char ; but liow far these
were unknown on the continent, and how many of these in dif-
ferent parts of our islands were really distinct, had not been
ascertained till Dr. Oiinthcr, so well known for his extensive
knowledge of the s})eeios of fishes, obtained numerous speci-
mens fro[n every part of the onntry, and by comparison with
all known continental species determined their speciHc differ-
ences. The striking and une.\pected result has thus been at-
tained that no less than fifteen well-marked 6|5ecies of frosh-wa-
tcr fiahcs are altogetlier peculiar to the British Islands. The fol-
lowing is the list, with their English names and localities : '
FiiKsn-WATBB FisuEi TKCtHAn t
E Bni
Ijiirii Nnme. Ensllab N»m<'. laeaWtj.
1. Salmo Arr7i^%ieMa..,Shorl-hM(la(l anlmon... .Firth of Fortli, Tivcci], Onte.
8. " Gal/iunah. . .Gnlwiiy Ma-troiit Gnlwny, West of Irolun J.
8. " OrrailfHtit. . .hovb Swniiis trout Lnkes of Orkney.
I Tlio li
r nnmea niu fonii&licJ to me liy ])r. Giiniher, nnd 1 linve ndJn] the
llic piipcn cDninining llie uigliml JeKripiions, and fiam Dr. Ilaiigli-
5.
C.
7.
8.
9.
•
10.
11.
Chap. XVI.] THE BRITISH ISLES. 317
Lntin Name. English Name. Locality.
4. Salmoferox Great lake-troat Larger lakes of Scotland, the
North of England, nnd Wales.
* ' stomachicus, . . Gillaroo trout Lakes of Ireland.
ni^rt/)«nnij.... Black-finned trout. Mountain lochs of Wales and
Scotlond.
Levenensis, . . .Loch Leven trout Loch Leven, Loch Lomond, Win-
dermere.
Peinsii Welsh char Llanberris lakes, North Wales.
ir<V/i/<7A6tt.... Windermere char Lake Windermere, and others in
North of England, and Lake
Bruiach in Scotland.
Killinensis,. . .Lough Killin char Killin Lake, in Mayo, Ireland.
Coin Cole's char Lough Eske and Lough Dan, Ire-
land.
12. *' (Srayi Gray 'a char Lough Melvin, Leitrim, Northwest
of Ireland.
13. Cortgonua clupeoides, The gwyniad, or scheIl3'..Loch Lomond, Ulleswater, Hawes-
water, and Bala Lake.
14. *' vandesius. . The vendace Lochmaben, Dumfriesshire.
15. ** poilan The pollan Lough Neagh and Lough Erne,
North of Ireland.
These fifteen peculiar fishes differ from each other and from
all British and continental species, not in color only, but in such
important structural characters as the form and size of the fins,
the number of the fin-rays, and the form or proportions of the
head, body, or tail. They are, in fact, as Dr. Giinther assures me,
just as good and distinct species as any other recognized species
of fish. It may, indeed, be objected that, until all the small lakes
of Scandinavia are explored and their fishes compared with
ours, we cannot be sure that we have any peculiar species. But
this objection has very little weight if we consider how our own
species vary from lake to lake and from island to island, so that
the Orkney species is not found in Scotland, and not one of the
peculiar British species extends to Ireland, which has no less
than six species altogether peculiar to it. If the species of our
own two islands are thus distinct, what reason have we for be-
lieving that they will be otherwise than distinct from those of
Scandinavia? At all events, with the amount of evidence we
already possess of the very restricted ranges of many of our spe-
cies, we must certainly hold them to be peculiar till they have
been proved to be otherwise.
318
ISLAND LIFE.
[Pa.
Tlio great spedulity of tlie Irish fislics is vtjrj' iiiterfstiiig, be-
cause it is just wlmt we ehoiild expect on the tlieory of evola-
tion. In Ireland the two main causes of epccitic change — isol:t-
tion and altered c-onditioiis — are each more powerful than in
Britain, Whatever difficulty continental fishes may have in pass-
ing over to Britain, that difficulty will certainly be increased by
the second eea passage to Ireland; and the latter country has
been longer isolated, for the Irish Sea with its northern and
southern channels is considerably deeper than the German Ocean
and the eastern half of the Eugllsli Channel ; so that, when the
last subsidence occurred, Ireland would have been an island for
some length of time wiien England and Scotland still formed
part of the continent. Again, whatever differences have been
produced by the exceptional climate of onr islands will have
been greater in Ireland, where insular conditions are at a maxi-
mum, the abundance of moisture and the equability of tern-
peratui-e being far more pronounced than in any other part of
Europe.
Among the remarkable instances of limited distribution af-
forded by these fishes, we have the Loch Stennis trout confined
to the little group of lakes in the mainland of Orkney, occupy-
ing altogether an area of about ten miles by three; the Welsh
char confined to tlie Llanborris lakes, about three mites in
length; Gray's char confined to Lough Mel vin, about seven miles
long; while the Lough Killin char, known only from a small
mountain lake in Ireland, and the vendace, from the equally
small lakes at Lochmabcn in Scotland, arc two examples of re-
stricted distribution which can hardly be surpassed.
Cause of Great !:<pectnU-tij in Flith^ii. — Tlie reason why fishes
alone should e.\hibit such remarkable local modifications in lakes
and islands is sufficiently obvious. It is dne to the extreme
rarity of their transmission from one lake to another. Just as
we found to be the case in oceanic islands, where the means
of transmission were iimple hardly any modification of species
occurred ; while, where these means were deficient, and individ-
nala once transported remained isolated during a long sneccseion
of ages, their forms and characters became so much changed as
to bring about what wo term distinct species or even distinct
Chap. XVI.] TUE BRITISH ISLES. 319
genera — so these lake fishes have become modified because the
means by which they are enabled to migrate so rarely occur. It
is quite in accordance with this view that some of the smaller
lakes contain no fishes, because none have ever been conveyed
to them. Others contain several ; and some fishes which have
peculiarities of constitution or habits which render their trans-
mission somewhat less difficult occur in several lakes over a wide
area of country, though none appear to be common to the Brit-
ish and Irish lakes.
The manner in which fishes are enabled to migrate from lake
to lake is unknown, but many suggestions have been made. It
is a fact that whirlwinds and waterspouts sometimes carry living
fish in considerable numbers and drop them on the land. Here
is one mode which might certainly have acted now and then in
the couree of thousands of years, and the eggs of fishes may have
been carried with even greater ease. Again, we may well sup-
pose that some of these fish have once inhabited the streams that
enter or flow out of the lakes, as well as the lakes themselves ;
and this opens a wide field for conjecture as to modes of migra-.
tion, because we know that rivers have sometimes changed their
courses to such an extent as to form a union with distinct river
basins. This has been effected either by floods connecting low
water-sheds, by elevations of the land changing lines of drain-
age, or by ice blocking up valleys and compelling the streams to
flow over water-sheds to find an outlet. This is known to have
occurred during the glacial epoch, and is especially manifest in
the case of the Parallel Koads of Glenroy, and it probably af-
fords the true solution of many of the cases in which existing
species of fish inhabit distinct river basins whether in streams or
lakes. If a fish thus wandered out of one river basin into an-
other, it might then retire up the streams to some of the lakes,
where alone it might find conditions favorable to it. By a com-
bination of the modes of migration here indicated, it is not diffi-
cult to undei'stand how so many species are now common to the
lakes of Wales, Cumberland, and Scotland, while others less able
to adapt themselves to different conditions have survived only
in one or two lakes in a single district; or these last may have
been originally identical with other forms, but have become
ISLAND LIKE.
riM
nioJified by tlie parlieuliir conditions of tlic lukc in which they
btivti found theuiBelvGB isolated.
Peculiar lint'ish /it^-cts. — We now come to tiie class of in-
sects, and here we hiive much more difficulty in deteriiiiiiing
what are the actual facte, because uew species are still bein^r
yearly discovered, and considernbie portions of Europe are but
imperfectly explored. It often happens that an insect is discov-
ered in onr islands, and for some years Britain is its only record-
ed locality; btit at length it is found on some part of the con-
tinent, and not unfrequently has been all the time known there,
but disguised by another name, or by being classed as a variety
of some other species. This has occurred so often that our best
entomologists have come to take it for granted that aU our sup-
posed peculiar British species are really natives of the continent,
and will one day be found there; and, owing to tiiis feeling, little
trouble has been taken to bring together the names of such as
from time to time remain known from this country oidy. The
view of the probable identity of our entire insect-fauna with that
of the continent is held by such well-known authorities a& Mr.
E. C Byo and Dr. D. Sharp for the beetles, and by Mr. li. T.
Stainton fur butterflies and mollis; but as we have already seen
that among two orders of vertebrates — birds and fishes — tbere
are nudoubtcdly peculiar British species, it seems to nic that
all tlie probabilities are in faror of there being a mnch larger
number of peculiar species of insects. In every other island
■where some of the vertebrates are peculiar — as in the Azores,
the Canaries, the Andaman Islands, and Ceylon — the insects
show an equal, if not a higher, proportion of speciality, and tliere
seems no reason whatever why tlio saino law should not apply
to us. Our climate is undoubtedly very distinct fi-om that of
any part of the continent, and in Scotland, Ireland, and Wales
■we possess extensive tracts of wild inoiintainous country where
a moist uniform climato. an alpine or northern vegetation, and a
considerable amount of isoiution offer all the conditions requi-
site for the preservation of some species which may have bo-
come extinct elsewhere, and for the slight niodilication of others
since our last separation from the continent. I think, therefore,
that it will be very interesting to take stock, as it were, of onr
Chap. XVI.] THE BRITISH ISLES. 321
recorded peculiarities in the insect world, for it is only by so
doing that we can hope to arrive at any correct solution of the
question on wliich there is at present so much difference of opin-
ion. For tlie list of Coleoptera with the accompanying notes I
am indebted to Mr. E. C. Kye ; and Dr. Sharp has also given me
valuable information as to the recent occurrence of some of the
supposed peculiar species on the continent. For the Lepidop-
tera I first noted all the species and varieties marked as British
only in Staudinger's " Catalogue of European Lepidoptera."
This list was carefully corrected by Mr. Stainton, who weeded
out all the species known by him to have been since discovered,
and funiished me with valuable information on the distribution
and habits of the species. This information often has a direct
bearing on the probability of the insect being peculiar to Britain,
and in some cases may be said to explain why it should be so.
For example, the larvae of some of our peculiar species of Tine-
ina feed during the winter, which they are enabled to do owing
to our mild and insular climate, but which the severer conti-
nental winters render impossible. A curious example of the
effect this habit may have on distribution is afforded by one of
our commonest British species, Elachista rufocinerea^ the larva
of which mines in the leaves oi Holcus mollis and other grasses
from December to March. This species, though common every-
where with us, extending to Scotland and Ireland, is quite un-
known in similar latitudes on the continent, but appears again
in Italy, the South of France, and Dalmatia, where the mild
winters enable it to live in its accustomed manner.
Such cases as this afford an excellent illustration of those
changes of distribution, dependent probably on recent changes
of climate, which may have led to the restriction of certain
species to our islands. For should any change of climate lead
to the extinction of the species in South Europe, where it is far
less abundant than with us, we should have a common and
wide-spread species entirely restricted to our islands. Other
species feed in the larva state on our common gorse, a plant
found only in limited portions of Western and Southern Eu-
rope; and the presence of this plant in a mild and insular cli-
mate such as ours may well be supposed to have led to the pres-
21
323 ISLAND LIFE. [Pim II.
ervation of some of tlie miiucroiis species wliicli iiru or Lave
Ijcen dependent on it.
Mr. MeLaclilan Lab kindly fiirnislted me with Eonic valnabic
information on certain species of Triclioptera, or caddis-fllee,
which seem to be pecnliar to onr islands; and this eoinpletea
the iist of orders which have been studied with snllicient care
to afford materials for such a comparison. We will now give
the list of peculiar British insects, beginning with tlie Lepidop-
tera, and adding siicli notes as Litvc been kindly supplied by the
gentlemen already referred to.
Lisr OF TUB Spkciks on Vahibties or Lefidopteba which, so faii as at rnes-
UNt KMOWX, *Utl CuXnSED TO TUB BRITISH I»I.ANPS.
(.Tie Fiyura SAow Ike Data when the SpfcUi leere Pint DttcriM.)
1. Poli/ommatia ditjitir. "Tlie Inrger copper." This fine inacct, once common in
■lie funo, but nov extinct oninB to extensire draiimgo, is genorallj' adinideJ
lo Lb pecalinr lo oar iilund, r1 iiU events as a, vnnelj or local foim. Its can-
lineiiut ally ilifiers consttmily in beinj; sTiialler nnd in Iiaving smxllcr ipoti;
lilt llic difference, tliaiish constant, is eo aliglit that it is now ciaastid ns u va-
liety under tlie nnmo of niiVim. Our insect may itierefore be iinied to be a
wcll-tnarkcd local farm of n coniincninl species.
2. Lycicna nsUarclie, var, Artaierxu. Tliis very dislincc Torm is conRiicd In Scot-
land and ilie North of England. The species of nhich it ii considered n vn-
Tia.y (more eenernllf known to English entamolosiils as P. a^islh) is found
in the Bouihcrn liatf o( Englnnd, and almost cven'ivlteie on tlic continent.
BoMntcKS.
a. Lilhoaa urieta. Norlli orii;ngliind(18Cl).
4. Ile|iialas liamull. rar. Beihlaailiia, .Shellnnd IsUnils (ISGii). A remni'kibl«
r>irm, in whicli the male is usiinliy yellow and bulT instead of pnro while, as in
the common funn.bul exceedingly variable In tint Bnd maikrugs.
C, £pieknBiileri/i rctietUa. SheemeiiB, Grnvescnd, nnd oilier localities along the
Thnrae* {1647}.
5. E. pnlla, rar. MiAVf/ii. Nenrl-ondon (1830?). Itnre; the iipecies in Central and
tjuiitliern Europe. (Doubtfully peculiar, in Mr. Sininton's opinion.)
NlXTD*.
T. AeroHiii-ln msririr. Scoilnnd only (I8n2). A dixlinL-t RpeciL-;.
8. Affraiii mlmtta. Canitiriilgcshire nnd llunling<lun8lilre funs, peilinps extinct
(18»fi.) The car. Mbnmlea U found in Finland and Lironin.
!l. A. AtiuiorHiii. Soutli and West (I8ii5). Distinct and not uncommon.
10. lHaMthfria liarrelH. Ireland (1864). Periinpt a form of the coniinentnl D.
lutea'jo, Mr. McLacliInn thinks.
Chap. XVI.] THE BRITISH ISLES. 323
11. Aporophyla aiistralis, var. Pascuea. South of England (1830?). This is a vr-
riety of a species othei'wise confined to the StnUh of Europe, and is thus espe-
cially interesting.
Geometry.
12. Boarmia gcmmaria, var. perfamaria. Near London (18CC). A large dark va-
riety of a common species, distinctly marked ; perhaps a good species, ns the
1ar\'a feeds on ivy, while the larva of B. gemmaria is said to refuse this plant,
and to die if it has nothing else to eat ; but Mr. McLachlan thinks this wants
confirmation.
13. Cidaria albulata, var. t/riseata. East of England (1835). A variety of a spe-
cies otherwise confined to Central and Southern Europe.
14. EupUhecia constrictata. Widely spread, but locol (1857). Lan'a on thyme.
Pyralidina.
15. Aglossa pinguinalis, var, Streatjieldi. Mendip Hills; unique (1830 ?). A re-
markable and distinct variety of the common ** tabby.''
10. Asopia pictalis. Unique (1830?). Perhaps an imported species.
17. Scoparia atpina, Scotland (1859).
TOBTRICIXA.
18. Teras Shepherdana. Fens of Cambridgeshire (1852).
19. Cochjflis dUucidana. South of England (1829). Scarce; larva in stems of the
wild parsnip.
20. Aphelia nigrovittana, Scotland (1852). A local foqpo of the generally distrib-
uted A. lanceolana.
2\. EudemisfuUgatM. Southeast of England (1828). Hare; on fleabane.
w2. Grapholitha navana. Generally distributed (1845). Doubtfully distinct from
continental species, in Mr. Stainton's opinion.
23. G. parvulana. Isle of Wight (1858?). Rare; a distinct species.
24. G. Weirana. South of England (1850). A distinct species.
TiN'EINA.
25. Tinea cochylidella, Sanderstead, near Croydon (1854). Unique.
2G. 7\ pallescentella. Near Liverpool (1854). Abundant; probably imported in
wool, Mr. Stainton thinks.
27. T. flavescentella. Near London (1829). Scarce; perhaps imported.
28. Acrolepia hettdeteUa. Yorkshire and county of Durham (1840). liare.
29. Argyresthia semifusca. North and West of England (1829). Scarce ; a distinct
species.
:\0. Geiechia divisella. A fen insect (1854). Rare.
3 1 . (i. ceUrella. West of Enghind (1854).
32. Bryophila poUtella. Moors of North of England (1854).
33. Lita fraterneUa. Widely scattered (1834). Lan-a feeds in shoots of Stellaria
uliginosa in spring. Mr. Stainton thinks it has been overlooked abroad.
34. Anacampsis sircomella. North and West of England (1854). Perhaps a mclanic
variety of the more widely spread A. tanioUUa.
^n. A. immaculatella. West Wickham (1834). Unique; a distinct species.
3G. Glyphipteryx cladiella. Eastern counties (1859). Abundant.
324 ISLAND LIFE. [Part IL
87. Glyphipteryx gchcmicolella. In several localities (1859).
2)8. Gracillaria straminella, Noith Britain (1850). Perhaps a local form of the
more southern G. elongeUa,
89. Ornix Loganella, Scotland (1848). Abundant, and a distinct species.
40? O. Devoniella. In Devonshire (1854). Unique.
41. Coleophora albicosta. Widely spread (1829). Common on furze (CJiex Euro*
pceus). May probably be found in the Northwest of France, where the food-
plant abounds.
42. C. mturateiia. South of England (1850). Abundant on broom.
43. C, inflatcL South of England (1857). On Silene ir^flata,
44. C. squamoselia. Surrey (1856). Very rare, but an obscure species.
45. C. aa/inella. On sea-coast (1 859). Abundant.
46. Perittia obscurepunctella. Widely scattered (1848). Larva feeds on common
honeysuckle in July. Mr. Stainton thinks it must have been overlooked on
the continent.
47. ElachUta flavicomella, Dublin (1856). Excessively rare, two specimens only
known.
48. E. coruortella, Scotland (1854). A doubtful species.
49. E. megerlella. Widely distributed (1854). Common. Larva feeds in grass
during winter and early spring.
50. E, obliquelia. Near London (1854). Unique.
51. E, eleockariella. North and East of England (1854). An obscure form.
52. E. subocellea. Widely distributed (1835). An obscure form ; perhaps mixed
on the continent with other species.
53. E. iriatomea. In chalk and limestone districts (1812). Abundant and distinct.
54. E. (riseriatelia. South of England (1854). Very local ; an obscure species.
55. Lit hocof lefts nigrescentella, Nortiiumberland (1850). liare ; a dark form of
L. Bremiella^ which is widely distributed.
56. L. irradiella. North Bntain (1854). A northern form of the more southern
and wide-spread L. iautella.
57. L. Iriguttel/a, Sandei-stend, near Croydon (1848). Unique; very peculiar.
68. L. ulicioUlla, In a few wide-spread localities (1854). A peculiar form.
59. L. Caledoniella. North Britain (1854). A local variety of the more wide-spread
L. corylifoHella.
60. Xr. Dunningtella, North of England (1852). A somewliat doubtful species.
61. Bucculatrix demaryella. Widely distributed (1848). liathcr common.
62. Tri/nrcttla squamatetla. South of England (1854). A doubtful species.
63. T. atrifroniella. South of England, also in Lancashire (1854). Very rare and
peculiar.
64. Nepticula ignohUieUa. Widely scattered (1854). On hawthorn ; not common.
65. A^. poterii. South of fingland ( 1 858). Bred from larvoj in Poterium sangutsorba.
66. N. quinquella. South of England (1848). On oak-leaves, very local.
67. N, apicella. Local (1854). Probably confused with allied species on the con-
tinent.
68. N. UeadlegtUa. Local (1854). A rare species.
Pterophorina.
69. Agdiitis Benntttii, East coast (1840). Common on Statice limontwn.
Chap. XVI.] THE BRITISH ISLES. 325
Wo have here a list of sixty-niue species, which, according to
the best authority, are, in the present state of our knowledge,
peculiar to Britain. It is a curious fact that only five of these
have been described less than twenty years ago ; and as during
all that time they have not been recognized on the continent,
notwithstanding that good colored figures exist of almost all of
them, it seems highly probable that many of them are really
confined to our island. At the same time, wo must not apply
this argument too rigidly ; for the very day before my visit to
Mr. Stainton, he had received a letter from Professor 2feller an-
nouncing the discovery on the continent of a species of our last
family, Pteropliorina, which for more than forty years had been
considered to be exclusively British. This insect, Plaiyptilia
siiniliddctyla (Pterophoriis isodactf/lus^ Stsiinton^B "Manual"),
had been taken rarely in the extreme nortli and south of our isl-
ands— Teignmouth and Orkney — a fact which seemed somewhat
indicative of its being a straggler. Again, seven of the species
are unique — that is, have only been captured once ; and it may
be supposed that as they are so rare as to have been found only
once in England, they may be all equally rare and not yet found
on the continent. But this is hardly in accordance with the
laws of distribution. Widely scattered species are generally
abundant in some localities; while, when a species is on the
point of extinction, it must for a time be very rare in the single
locality where it last maintains itself. It is then more probable
that some of these unique species represent such as are almost
extinct than that they have a wide range and are equally rare
everywhere ; and the peculiarity of our insular climate, com-
bined with our varied soil and vegetation, offers conditions which
may favor the survival of some species with us after they have
become extinct on the continent.
In the list here given nine are recorded as varieties, while ten
more, in Mr. Stainton's opinion, ought probably to be classed as
varieties or local forms of other species, making nineteen in all.
This leaves no less than fifty undoubted species not yet found
beyond our islands ; and though Mr. Stainton thinks that most
of these will ultimately be found on the continent, we can hardly
doubt, both from general considerations dependent on the laws
ISLAND LIFE.
[PutU
of dietplbiitioii, and from the peculiar liabits, eonspiciiouB ap-
pearance, and restricted range of many of our species, tliut a
very cousidernble nnniber will remain permanently as peculiar
British ineects.
Peculiarities of the hie of Man I^epidoptera. — Before quit-
ting the Lepidoptera, it will be well to notice some very inter-
esting examples of local modification, appareutly brought about
by extreme conditions of CNposure and insulation, and which
throw some light on the way in which local forms, varieties, or
species may ho produced. This interesting phenomenon occurs
in the Isle of Man, where Mr. Edwin Birchall lias collected
Lepidoptera assiduously, and has discovered a number of varie-
ties, apparently peculiar to the island, of which he has been so
good as to send me specimens accompanied by some valuable
notes.
The Isle of Man has no woods, bogs, or heaths, the mountains
being mostly covered with grass and rocks, so that a very abun-
dant insect fauna cannot be expected. Sixteen species of butter-
flies have been observed, and of these only one — the common
tortoise-shell ( Vaiiesaa urticcE) — presents any peculiarity. This,
Iiowcver, la always remarkably small, a specimen rarely being
found to equal the smallest: English specimens ; so that we must
look upon it as n dwarf raeo developed in tho islnnd and con-
fined to ic.
Tho following moths also present definite peculiarities;
1. Apvtli laeertea. var. I'his is nrn (-niTisb-Uack color, witliliardit aiiTmnL'kinen,
All arc alike, and are verv ilistiiR't from Ilie cominoii trpe of llie upccies, nhieli
U nbunilniit la Wiil«j,
a. Cirrhadia xtramptlina, var. Tliia is mucli darker nnd more ricEilj colored tlinn
tliu English fujin, ihe j-ellnff Imtid being redooed to a nan-ow line, tKunolimcs n
mere tlii'end. This noiild doiibileia be rcgsrdeil ns a (iistinct Rpccica if it uc-
curicJ niili equni oonstnnc]' in some more remolo inland.
3. Dianihtcda captupktii, i-ar. TliiMi* an exceedingly dnrk and richly mnrked form
at tlio Irlnh 1>. capm/ikUa, ilKtf n local variety, Mr. Birclioll thinks, ■o( /J. e-ir-
i. Z>iantkaeia tatia, var. This \» anoiher dntk form of n rnre Irlah and conliiicniiil
J>. Ttphratia bivndularia, var. Tliis is an eTEcecdingly dark foim. nnd difleri bo muvli
trom North uf F.nglnnd ipecimens n» lu hnvo nil ilic ni>[«Brancc of another ipo-
cioa. Mr. Birchnll hnt hred ii from captured poreiitt, nnd fitids that the produce
is this durk furni only.
Chap. XVI.] THE BRITISH ISLES. 327
We will now pass on to the Coleoptera, or beetles, an order
which has been of late years energetically collected and carefully
studied by British entomologists.
List of tue Species of Beetles which, so fab as at Present Known, abb
Confined to the Bbitisu Islands.
CABABIDiE.
1 . Dromius vectensis (Rye). Common in the Isle of Wight, not known elsewhere.
2. *Hnrpalu8 latus, var, metallescens (Rye). Unique, but very marked. South
coast.
3. Stenolophus derelictus (Dawson). Unique. North Kent.
IlELOrHORIDiE.
4. ^Ochthehius Poweri (Rye). Very marked. South coast. A few specimens only.
Brachtklttra.
r». ^Aleochara IHhernica (Rye). Ireland. Mountain-tops.
G. * Oxypoda rupicola (Rye). Scotland. Mountain-tops. Several specimens.
7. * *' Edinensis (Sharp). Scotland.
8. *' verecunda (Sharp). Scotland.
9. ** Waterhousei (Rye). London district.
10. Homalota eximia (Shar])).
clavipes (Sharp). Scotland ; on mountains. Not rare.
ohlongiuscula (Sharp). Scotland, perhaps also Swiss.
princeps (Sharp). A coast insect.
curtipennis (Sharp).
eiarata (Shorp).
puberula (Sharp).
indiscreta (Sharp). "^
a/nco/or (Sharp). fSome Continental authors deny that there are
(/*!rmana (Sharp). ( good species (Sliarp).
setigera (Sharp). J
Sharpi (Rye). Very marked ; unique.
22. *Bn/oporus castaneus (Hardy and Bold). Very marked; unique. Northumber-
land hills.
23. *Stenu8 oscillator (Rye). Unique. South coast
2*. *Srop(puit Ryti (Wollaston). Very distinct. Dorset coast. Several specimens.
25. *Trogopnlaus spinicollis (Rye). Mei*sey estuary. Unique. Most distinguisha-
ble ; nothing like it in Europe.
2C. L^steva Shnrpi (Rye). Scotch hills.
27. Kudectus Whitei (Sharp). Scotch hills. Probably a variety of E. Giraudi of
Austria (the only European species) ^fif« Kraatz (Sharp).
28. ^Homalium rugullpenne (Rye). Exceedingly marked form. Northern, western,
and southern coasts, liare.
rSELAPlIID^.
20. Bryaxis cotus (Sharp). Coast.
30. " Waterhousei {Rye). Coast.
n.
12.
13.
14.
15.
10.
17.
18.
10.
20.
21. ♦
328 ISLAND LIFE. [Pabt IL
81. ^Bythinta glahratus (Rjc). Sussex coast A few specimens; very distinguish-
able ; myrmecophilous OXses \\\ ants' nests).
TsiCHOPTERYOIDiB.
82. Ptinelh maria (Matthews).
38. Trichopteryx Sara **
34. ** Poweri **
35. " Edithia "
36. ** cantiana **
37. ** fuBcula **
38. '* Kirhii **
39. '* fratercula '*
40. ** Waterhousei "
41. ** championis **
42. ♦* Jansoni **
48. '* seminitent '*
44. '* suffocata (Halidaj). Ireland.
45. ** dispar (Matthews).
46. '* carbonaria (Matthews).
47. Ptilium HaUdayi (Matthews).
48. *' CaUdonicum (Sharp). Scotland. Very marked form.
49. ** insigne (Matthews).
50. Actidium concolor (Sharp). Scotland. Very marked.
51. Ptenidium Kraatzii (Matthews).
Anisotomidje.
62. ^Agathidium rhinoceros (Sharp). Old fir-woods in Perthshire. Local ; many
specimens. A very marked species.
53. Anisotoma similaia (Rye). Uniqne. South of England.
54. *^ lunicollis (Rye), Northeast and South of England. A very marked
form. Several specimens.
55. * Anisotoma clavicomis (Kye). Unique. Scotland.
PlIALACRID.B.
56. ^Phalacrus Brisouti (Rye). A few specimens. South of England.
Crtptophagid-e.
57. Atomaria Wollastoni (Sharp). Unique. Scotland.
58. " </*risa (Rye). Unique. South of England.
Lathrididje.
59. Corticaria Wollastoni (Waterhouse). South coast.
BTRRHIDiE.
60. Syncalypta hirsuta (Sharp).
Elaterid^.
61. Elater coccinatus (Rye). Very marked, bnt possibly a variety of the European
E. pranutus. South of England.
Chap.XVLJ the BRITISH ISLES. 329
Telephosidjs.
C2. *Telephortis Darmnianus (Sharp). Scotland, sea-coast. A stunted form, of ab-
normal habits.
Ctphonidje.
C3. Cifphon punctipennit (Sharp). Scotland.
Amthicidje.
64. Anthicus salinits (Crotch). South coast
G5. * *' Scoticus (Rje). Loch Leven. Very distinct. Many specimens.
CCRCULIONIDJS.
C6. *Cathormiocerus maritimus (Rye). A few specimens on our south coast. A cu-
rious genus, only found elsewhere on the coasts of the Mediterranean.
67. *Ceuthorhynchus contractus, rar.//a///pe« (Crotch). Lundy Island. Several spec-
imens. A curious variety only known from this island.
68. *Lio8omu8 troglodytes (Rye). A very queer foiin. Two or three specimens.
South of England.
69. *Apion Jtyei (Blackburn). Shetland Islands. Several specimens.
IIaltxcid^.
70. Thyamis agilis (Rye). South of England. Many specimens.
** (listinguenda {Uye), South of England. Many specimens.
71. *Psylliodes luridipennis (Kutschern). Lundy Island. A very curious form, not
uncommon in this small island, to which it appears to be confined.
CoCCINELLIDA.
72. Scymnut lividus (Bald). Northumberland. A doubtful species.
Of the seventy-two species of beetles in the preceding list, a
considerable number, no doubt, owe their presence there to the
fact that they have not yet been discovered or recognized on the
continent. This is almost certainly the case with many of those
which have been separated from other species by very minute
and obscure characters, and especially with the excessively mi-
nute TrichopterygidoB described by Mr. Matthews. There are
others, however, to which this mode of getting rid of them will
not apply, as they are so marked as to be at once recognized by
any competent entomologist, and often so plentiful that they can
be easily obtained when searched for. Of this class are the
twenty-three species whose names are marked with an asterisk
(*), being those which, in Mr. Rye's opinion, are most likely to
be peculiar to the localities where they are found, if any are ;
but of this he is still somewhat sceptical. Six of these are unique,
leaving seventeen which have occurred cither rarely or in some
380
ISI.AND LIFE.
[Pabt 1L
abnudiiiH-c. Dividing the probaLly pcculiitr species according
to locality, we find that the South of England has produced 9,
North o£ England 2, Scotland 6, Ireland 1, Shetland Islands 1,
and Lundy Ishind 2. These nuinbei-a are, generally speaking,
proportionate to the ricbnesB of the district and the amount of
work bestowed upon it; Scotland, however, giving more than
its dnc proportion m this reepeet, which must be imputed to its
really possessing a gi'eatei* amonnt of speciality. The single pe-
culiar Irish species stands as a luonnment of our comparative ig-
norance of the entomology of the sister isle. The pccnliur spe-
cies of Apion in the Slielland Islands is interesting, and may be
connected ivith the very peculiar cliinatal conditions there pre-
vailing, which liave led in some cases to a change of habits, bo
that a species of weevil {Otiorhynchus maurus) &\viay& found on
mountain-sides in Scotland, hero ocem-s on the sea-shore. Still
more curious is the occurrence of two distinct forms (a species
and a well-marked variety) on the small granitic Lundy Island
in the Bristol Channel. This island is about three miles long,
and twelve from the coast of Devonshire, consisting mainly of
granite with a little of the Devonian formation, and the pres-
ence here of peculiar insects can only be duo to isolation with
special conditions, and immunity from enemies or competing
forms. When we consider the similar islands off the coasts of
Scotland and Ireland, with the Isle of Man and the Scilly Isl-
ands, none of wliieh have been yet thoroughly explored for bee-
tles, it is probable that many similar e:[amples of peculiar isor |
latcd forma remain to be discovered.
Mr. Kyo hardly thinks it possible that the Droinim vectem
can really bo peculiar to the Isle of "Wight, although it is abua<
dant there, and has never been found elsewhere; I)ut the cu
of Lundy Island renders it less improbable; and when we conJ
sider that the Aru?n ItaUcuin, Valandntha fi/h-atica, and peft
haps one or two other plants are found nowhei-e else
British Isles, we must admit that the same causes which havi
acted to restrict the range of a plant may liavo had a similar ef^f
feet witli a beetle.
I must also notice tho Cathormtocerits mariitmus, becanse itfV
only near ally inliabits the coasts of tho Mediterranean ; and it
CuAP.XVL] THE BRITISH ISLES. 331
thus offers an analogous case to the small moth, Elachista rufo-
cinereaj which is found only in Britain and the extreme South
of Europe. Looking then at what seems to me the probabilities
of the case from the standpoint of evolution and natural selec-
tion, and giving due weight to the facts of local distribution as
they are actually presented to ns, I am forced to differ from the
opinion held by our best entomological authorities, and to be-
lieve that some considerable proportion of the species which in
the present state of our knowledge appear to be peculiar to our
islands are, not only apparently, but really, so peculiar.
I am indebted to Mr. Robert McLachlan for the following: in-
formation on certain Trichopterous Neuroptera, or caddis-flies,
which appear to be confined to our islands. The peculiar aquatic
habits of the larvse of these insects — some living in ponds or
rivers, others in lakes, and others again only in clear mountain
streams — render it not improbable that some of them should
have become isolated and preserved in the mountain districts
of our western coasts, or that they should be modified owing to
such isolation. In these insects the characters depended on to
separate the species are wholly structural, and the care with
which Mr. McLachlan has studied them renders it certain that
the species here refeiTed to are not mere varieties of known con-
tinental forms, however closely they may resemble them in form
and coloration.
Tkichopteba Peculiar to the British Isles.
1 . Setodes argentipuncteJla, — Tliis species is known only from the lakes Winder-
mere and Killamey. It has recently been described by Mr. McLachlan, and is quite
distinct from any known species, though allied to S, punctata and S. viridiSy which
inhabit France and Western Euroi>e.
2. Rhyacophila munda. — Described by Mr. McLachlan in 18G3. A very distinct
species, found only in mountain streams in Wales and Devonshire.
3. Philopotamus instdaris (? a variety of P. montanus). — This can hardly be
termed a British species or variety, because, so far as at present known, it is peculiar
to the island of Guernsey. It agrees structurally with P, montanu$^ a species found
both in Britain and on the continent, but it differs in its strikingly yellow color, and
less pronounced markings. AW the specimens from Guernsey are alike, and resident
entomologists assured Mr. McLachlan that no other kind is known. Strange to say,
some examples from Jersey differ considerably, resembling the common European
and British form. Even should this peculiar variety be at some future time found
on the continent, it would still be a remarkable fact that the form of insect inhabit-
333 ISLAND LIFE. [['Anr II.
ing two small itJands only liveiiiy miles npnrt should conscanlly difTer ; but as Jenty
is between Guernsey nnil ilie const, it seems jiisi jiosfibte ihnt iha mora insutnr con-
diliuns, mid pei'linps some pociilinrity uf tlio soil nnd wnter in ihc former island, liuTe
I'enlly led to the produclion ur prvsei-ration of u well-marked rari«ty of insect.
Za»rf and Fresh-water S/iells. — As regards the land and f resli-
water moUiieca, it seems difficult to obtain accurate information.
Several species Iiave been recorded as British only ; but I am
informed by Mr, Gwyn Jefiries that most of these are decidedly
continental, wiiile a few may be classed as varieties of continental
Bjieeies. ATOordlng to the late Mr. Lovell Keeve, the following
species nro peculiar to our islands; and although the lirst two
seem exceedingly doubtful, yet the last two, to which alone we
accord the dignity of capital type, may not improbably be pecul-
iar to Ireland, being only found in the remote southweeteru
mountain region, where the climate possesses in the highest
degree the insular characteristics of a mild and uniform tem-
perature with almost perpetual moisture, and where several of
the peculiar Irish plants alone occur.
1. Cgclai pisidiaidet.-^A small Lividre shell found iu cnniils. rcrlmpa
of C. cnrweiiM or C. r,
2. AniinUia Grai,
on tlie banks of lii
3. GKOXALtcus VACULOSUS.— A beautiful slug, blnck, spottsJ vrilh jellonr or
white. It is found on rocbs on ihe shores ofLoke CuTDgh, south of Cnsllemain Bny,
in Kerry. It wna discovered in ISiS, nnd bus never been funnd in any olher IocbI-
iry. An allied species is fonnd in Portognl and France, uhich Mr, Uwyn Jefiriei
IhinliB may be identical.
4. Iauvxx itivoLUTi. — A beautiful pond-snnil witli a small polished ambcr-coloreilfl
chell, found only in a sinnll alpine hike nnd i
Mountain, near Ihe Lakes orKillarncy. It appears to be a very distinct gpcclea, m
nearly allied to L. gUiiaota, wiiicli is not found in Ireland. It was discovered in
1832, and has frequently been obtained since in the same locolily.
The facts — that these two last-named species Lave been known i
for about forty or fifty years respectively ; that they have neveq
been found in any other locality than the above-named vei
restricted stations ; nnd that they have not yet been clearly idenJ
tified with any continental species — all point to the eonclusioifl
that they are the last remains of peculiar forms wliicli hav^
everywhere else become extinct.
—A small bivalve aheli found in en
ico/n, according to Sir. Gwyn Jeffrie
iiiana. — A small univalve shell allied to llie periwinkles, fonnd
Thames lietivccn Greenwich and Giavesend, on the mud at Ura
Chap. XVI.] THE BRITISH ISLES. 333
Peculiarities of the British Flora. — Thinking it probable that
there must also be some peculiar British plants, but not finding
any enumeration of such in the British Floras of Babington,
Hooker, or Bentham, I applied to the greatest living authority
on the distribution of British plants, Mr. II. C. Watson, who
has very kindly given me all the information I required, and I
cannot do better than quote his words. He says, " It may be
stated pretty confidently that there is no ' species ' (generally
accepted among botanists as a good species) peculiar to the Brit-
ish Isles. True, during the past hundred years, nominally new
species have been named and described on British specimens
only, from time to time. But these have gradually come to be
identified with species described elsewhere under other names;
or they have been reduced in rank by succeeding botanists, and
placed or replaced as varieties of more widely distributed species.
In his ' British Rubi,' Professor Babington includes as good spe-
cies some half-dozen which he has, apparently, not identified
with any foreign species or variety. None of these are accepted
as * true species,' nor even as * sub-species,' in the ' Students' Flora,'
where the brambles are described by Baker, a botanist well ac-
quainted with the plants of Britain. And as all these nominal
species of Rubi are of late creation, they have truly never been
subjected to real or critical tests as ' species.' "
But besides these obscure forms, about which there is so much
difference of opinion among botanists, there arc a few flowering
plants which, as varieties or sub-specieSy are apparently peculiar
to our islands. These are: (1) Ileliantheninm Breweri^ an an-
nual rock-rose found only in Anglesea and Holyhead Island
(classed as a sub-species of IL guttatutn by Hooker and Babing-
ton) ; (2) liosa Ilibemica^ found only in North Britain and Ire-
land (a species long considered peculiar to the British Isles, but
said to have been recently discovered in France) ; (3) (Enanthe
fluviatilisy a water-drop wort, found only in the South of Eng-
land and in one locality in Ireland (classed as a sub-species of (E.
phellandrixim by Hooker) ; (4) Hieracium iricuin, a hawkweed
found in North Britain and Ireland (classed by Hooker as a
sub-species of U, Lawsotiij and said to be " confined to Great
Britain").
331: ISLAND LIEE. [PutU.
Two othef species are, so far as tlie Europenn flora is con-
cerned, peculiar to Britaiit, being iiativce of Nortli America,
and they are very interesting because they are certainly both
truly indigenous ; that is, not introduced by human agency.
These are: (1) SpirajUliea liomttmoviana, an orchid allied to
our lady's -tresses, widely distributed in North America, but
only found elsewhere in the extreme southwest corner of Ire-
land : and (2) Erlocaalon 8eptangui.are^ the pipewort — a cnrlous
North American water-plant, found in lakes in the Ilebrides and
the West of Ireland. Along with these we may perhaps class
the beautiful Irish filmy fern TricAomanc^ j-adicana, which in-
liabits the Azores, Madeira, and Canary Islands, the Southwest
of Ireland, Wales, and formerly Yorkshire, but is not certainly
known to occur in any part of continental Europe (except, per-
haps, the Sonthwest of Spain), though found in many tropical
countries.
We may liere notice the intei'estiiig fact that Ireland possesses
no less than twenty species or sub-species of flowering plants
not found in Britain, and some of these tna// be altogether pe-
culiar. As a whole they show the effect of tlie pre-eminently
mild and insular climate of Ireland in extending the range of
some Soutli European species. The following lists of these
plants, with a few remarks on their distribution, will be found
interesting:
I.19T or Imsu I'loiveuino I'lants which ark not I'oi'su is Ubitain,
1. IMimtitmun gatialum. IrelnnJ, nenr Cotk, nnd on an island off iha coast of
Uiilwny (iilso Chonnol Inlands, Fi'aiicc, Ilnly).
2, Arevaria ciliatii. Soutliwcst of Irelnml (nUo AiivBrgne, Pyrenees, Crele). A
viti'iet^r oflliie sp«cieii Im* been reconily found in PembrokeiiUire.
8. Sanfraya nmbrovi. West of Irelnnd {x\to Nonliern fipain, I'oi'lugil).
4. ■■ gemn. Soutlmut of Irelnnd (uliHi I'yreneei).
fi. " hiftuta. Soutlmest of Irelnnil (nliia Pyrenees).
6. Saxi/raga hiria (hi/pnoiJei iub-tp.). Souili of Ireland, nppnrcntly unknoivn an
7. Inula talieiiui. West of Ireland (Middle urn] Sonili riurore).
8. Krica 3Ueditrrranta. West oflrelnnd (West of Frnnce, Spnin,
». •' Haetiana (ttlmliz eub-ap.) Went of IreUnd (Spnin).
10. Arbvtiti vaah. Soutliweti of Iieliind (Nouih of KmtiM nnd .Spnin).
11. ttaliriii-iii poli/ali-i. West of IMnnJ (We« of France nnd Spnlri)-
VI, Pinguicvla graiiJiJiora, Southwest orirolaiid(We«HifFnince,S|wi«, Alps, etc.).
Chap. XVI.] THE BRITISH ISLES. 335
i;^. Neotinea intacta. West of Ireland (France, South of Europe).
14. Spiranthea Romanzoviana. Southwest of Ireland (North America).
Ii>. Sisyrinchium Dermwiianum. West of Ireland (? introduced; North America).
IG. Potamogeton longifolius (JucenB var.). West of Ireland, unique specimen.
17. ** Kirkii (natans sub-sp.). West of Ireland (Arctic Europe).
18. Erlocaulon aeptangulare. West of Ireland, Skye, Hebrides (North America).
1 i). Carex liuxbaumii. Northeast of Ireland, on island in Lough Neagh (Arctic and
Alpine Europe, North America).
20. Ciilamagi'ostis si ric ta, rar. //oo^-erl. On the shores and i>lands of Lough Neagh.
The species occurs at one locality in Cheshire (Germany, Arctic Europe, and
North America).
We find Iiere nine Southwest European species which probably
liad a wider range in mild preglacial times, and have been pre-
served in the South and West of Ireland owing to its milder
climate. It must be remembered that during the height of the
glacial epoch Ireland was continental, so that these plants may
have followed the retreating ice to their present stations and
survived the subsequent depression. This seems more probable
than that, so many species should have reached Ireland for the
lirst time during the last union with the continent subsequent
to the glacial epoch. The arctic, alpine, and American plants
may all be examples of species which once had a wider range,
and which, owing to the more favorable conditions, have con-
tinued to exist in Ireland while becoming extinct in the adjacent
parts of Britain and Western Europe.
As contrasted with the extreme scarcity of peculiar species
among the flowering plants, it is the more interesting and unex-
]>ected to find a considerable number of peculiar mosses and
Ilepatica?, some of which present us with phenomena of distri-
bution of a very remarkable character. For the following lists
and the information as to the distribution of the genera and
species I am indebted to Mr. William Mitten, one of the first
authorities on these beautiful little plants.
List of the Species op Mosses and Hepaticje which are Pkcuuar to the
British Isles or not found in Europe.
{Those belonging to non- European genera in italics.)
Mosses.
1 . Syste^iam mtiliicapsniare Central and South England.
2. ** Mittenii South of England.
336 ISLAND LIFE. [Pabt II.
3. Campylopus Slmwii North Britain.
4. *' setifolius Ireland.
5. Seligeria calcicola South of England.
6. Pottia viridifolia South of England.
7. Leptodontiiim recurvifulinm Ireland and Scotland.
8. Tortilla Woodii Ireland.
9. *' Hibernica Ireland.
10. Streptopogon gemmasrtns Sussex.
11. Grimmia subsquarrosa. North Britain.
12. ** Siirtoni North Britain.
13. Glyphomiirium Davicsii On basalt generally.
14. Zygodon Nowellii North Britain.
15. Bry iim Barnesii North Britain.
16. Hookeria latevirens Ireland and Cornwall (also Madeira).
1 7. Daltonia splachnoides Ireland.
HlSPATICiE.
1. Gymnomitrium crenulatum West of England, Ireland.
2. Radula voluta Ireland and Wales.
8. Acrobolbus WUsoni Ireland.
4. Lejeunia cafi/ptri/olia Cornwall, Lake district, Ireland.
5. ** microKopica Ireland.
6. Lophccolea spicata Ireland.
7. Juiigermannia cuneifolia Ireland.
8. ** doniana Scotland.
9. Pelalophyllum RaJfsii West Biitain, Ireland.
Many of tlie above are minute or obscure plants, and are
closely allied to other European species with which they may
have been confounded. We cannot, therefore, lay any stress on
these individually as being absent from the continent of Europe,
80 much of which is imperfectly explored, though it is probable
that some of them are really confined to Britain. But there are
a few — indiciited by italics — which are in a very diflFerent cate-
gory ; for they belong to genera which are altogether unknown
in any other part of Europe, and their nearest allies are to be
found in the tropics or in the Southern Hemisphere. The three
non-European genera of mosses to which we refer all have their
maximum of development in the Andes, while the three non-
European IlepaticoB appear to have their maximum in the tem-
perate regions of the Southern Hemisphere. Mr. Mitten has
kindly furnished me with the following particulars of the dis-
tribution of these genera :
Chip. XVI.] THE BRITISH ISLES. 337
Streptopogon is a comparatiyely small genus, with seven species in the Andes,
one in the Ilimalayns, and three in the south temperate 2M>ne, besides our English
species.
Daltonia is ft large genus of inconspicuous mosses, having seventeen species in
the Andes, two in Brazil, two in Mexico, one in the Galapagos, six in India and
Ceylon, five in Java, two in Africa, and three in the antarctic islands, and one in
Ireland.
HooKERiA (restricting that term to the species referable to Cjclodictjon) is still a
large genus of handsome and remarkable mosses, having twenty-six species in the
Andes, eleven in Brazil, eight in the Antilles, one in Mexico, two in the Pacific isl-
ands, one in New Zealand, one in Java, one in Indin, and five in Africa — besides our
British species, which is found also in Madeira and the Azores, but in no part of
Europe proper.
These last two are very remarkable cases of distribution, since
Mr. Mitten assures ine that the plants are so markedly different
from all other mosses that they would scarcely be overlooked in
Europe.
The distribution of the non-European genera of Hepaticse is
as follows :
AcROBOLBCB. A Small genus found only in New Zealand and the adjacent isl-
ands, besides Ireland.
Lejeunia. a very extensive genus abounding in the tropical regions of America,
Africa, the Indian Archipelago, and the Pacific islands, reaching to New Zealand and
anbuctic America, sparingly represented in the British and Atlantic islands and in
North America.
Petalophyllum. a small genus confined to Australia and New Zenlnnd in the
Southern Hemisphere, and Ireland in the Northern.
We have also a moss — Myurium Hebridarum — foimil only in Scotland and the At-
lantic islands ; and one of the Hcpaticoe — Mastitjophara Woodsii — foimd in Ireland
and the Himalayas, the genus being most developed in New Zealand and unknown
in any part of continental Europe.
These are certainly very interesting facts^ but they are by no
means so exceptional in this group of plants as to throw any
doubt upon their accuracy. The Atlantic islands present very
similar phenomena in the Rhamphidium purpuratum^ whose
nearest allies are in the West Indies and South America; and
in three species of Sciaromium, whose only allies are in New
Zealand, Tasmania, and the Andes of Bogota. An analogous
and equally curious fact is the occurrence in the Drontheim
mountains, in Central Norway, of a little group of four or five
peculiar species of mosses of the genus Mnium, which are found
22
»LAKD LIFE.
an.
nowhere else; althoiigli tlie genus extends over Europe, lotlia,
and the Soutliern lleuiisphere, Liit always represented by a very
few wide-ranging species except in this one mountain gronp,"
SncU facts eliow us tbe wonderful delicacy of the balance of
conditions which determine the existence of particular species
in any locality. The spores of mosses and HepaticiB are so mi-
nute that they must be continually carried through the air to
great distances, and we can hardly doubt that, so far as its pow-
ers of difEnsion are concerned, any species which fruits freely
might soon spread itself over tbe whole world. That they do
not du so must depend on peculiarities of liabit and constitution,
which lit the diEEcrent Bpeciefl for restricted stations and special
climatic conditions ; and accoi'ding as the adaptation is more
general, or the degree of specialization extreme, species will have
wide or restricted ranges. Although their fossil remains have
been i-arely detected, wc can hardly doubt that mosses have as
high an antiquity as ferns or Lycopods; and, coupling this an-
tiquity with their great-powers of dispersal, we may understand
how many of the genera have come to occupy a number of de-
tached areas scattered over the whole earth, but always such as
afford the peculiar fonditious of climate and soil best suited to
them. The repeated changes of temperature and other climatic
conditions, which, as we have seen, occurred through alt the later
geological epochs, combined with those slower changes caused
by geographical mutations, mnet have greatly affected the dis-
tribution of such ubiquitous yet delicately organized plants as
mosses. Throughout countless ages they muet have been in a
constant state of comparatively rapid migration, driven to and
fro by every physical and organic change, often subject to mod-
ification of structure or habit, but always seizing upon every
available spot in which they could even temporarily raurntain
themselves.
Here, then, we have ft group in which there is no question of
the means of dispersal, and where the difUeulties that present
themselves arc not how the species reached the remote localities
in which they are now found, but rather why they have not cs-
n indebred lu Mr. Mitt
Chap. XVI.] THE BRITISH ISLES. 339
tablished themselves in many other stations which, so far as we
can judge, seem equally suitable to them. Yet it is a carious
fact that the phenomena of distribution actually presented by
this group do not essentially difEer from those presented by the
higher flowering plants which have apparently far less diffu-
sive power, as we shall find when we come to treat of the floras
of oceanic islands ; and we believe that the explanation of this
is, that the life of species, and especially of genera, is often so
prolonged as to extend over whole cycles of such terrestrial mu-
tations as we have just referred to; and that thus the majority
of plants are afforded means of dispersal which are usually suffi-
cient to carry them into all suitable localities on the globe.
Ilence it follows that their actual existence in such localities de-
pends mainly upon vigor of constitution and adaptation to con-
ditions, just as it does in the case of the lower and more rapidly
diffused groups, and only partially on superior facilities for dif-
fusion. This important principle will be used further on to af-
ford a solution of some of the most difficult problems in the
distribution of plant-life.
Concluding Remarks on the Peculiarities of the British Fauna
and Flora. — The facts, now, I believe, for thfe first time brought
together, respecting the peculiarities of the British fauna and
flora are sufHcient to show that there is considerable scope for
the study of geographical distribution, even in so apparently un-
promising a field as one of the most recent of continental islands.
Looking at the general bearing of these facts, they prove that
the idea so generally entertained as to the biological identity of
the British Isles w^ith the adjacent continent is not altogether
correct. Among birds we have undoubted peculiarities in at
least three instances; peculiar fishes are much more numerous,
and in this case the fact that the Irish species are all different
from the British, and those of the Orknevs distinct from those
of Scotland, renders it almost certain that the great majority of
the fifteen peculiar British fishes are really peculiar, and will
never be found on the Etiropeau continent. The mosses and
Ilepaticoe also have been sufficiently collected in Enroi)e to ren-
der it pretty certain that the more remarkable of the peculiar
British forms are not found there. Why, therefore, it may well
840
ISLANn LIFE.
Til.
be asked, eIiouUI tliere not be a. proportionate number of pecul-
iar Britisli insects! It is true that numerous species have been
first discovered in Britain, and Bubsoquently on tbe continent;
but we have many species which have been known for twenty,
thirty, or forty jeure, some of which are not rare with us, and
yet have never been found on tlie continent. We liave also
the curious fact of our outlying islands, such as the Shetland
Isles, the Isle of Man, and the little Lundy Island, possessing
each some peculiar forms which certainlij do rot exist on onr
jmncipal island, which has been so very thoroujjhly worked.
Analogy, therefore, would lead us to conclnde that many other
species would exist on our islands and not on the continent ; and
wlien we find that a very large number (150), in three orders
only, are eo recorded, we may, I think, be aura that a considera-
ble portion of these (though how many we cannot say) are really
endemic British species.
The general laws of distribution also lead us to expect such
phenomena. Very rare and very local species are such as are
becoming extinct; and it is among insects, which are so exces-
sively varied and abundant, which present bo many isolated
forms, and which, dven on continents, afford numerous examples
of very rare species confined to restricted areas, that we should
have the best chance of meeting with every degree of rarity
down to the point of almost complete extinction. But we know
that in all parts of the world islands are the refuge of species
or groups which Iiave become extinct elsewhere; and it is tlierc-
fore in the highest degree probable that some species which
have ceased to exist on the continent shonld be preserved in
eomc part or other of our islands, especially as these present
favorable climatic conditions such as do not exist elsewhere.
There is therefore a considerable amonnt of harmony in tlie
various facts adduced in this chapter, as well as a complete ac-
cordance with what the laws of distribution in islands would
lead lis to expect. In proportion to the species of birds and
fresh-water fishes, the number of insect-forms is enormously
great, eo that the numerous species licre recorded ns not yet
known on the continent arc not to be wondered at; while it
would, I think, be almost an anomaly if, with peculiar birds and
CiLiP.XVI.] THE BRITISH ISLES. 341
fisbos there were not a fair proportion of peculiar ineecta. Our
entomologists should therefore give up the assumption that all
our insects do exist on the continent, and will some time or
other be found tliere, as not in accordance with the evidence ;
and when this is done, and the interesting peculiarities of some
of our smaller islands are remembered, the study of our native
animals and plants in relation to those of other countries will
acquire a new intei*est. The British Isles are said to consist of
more than a thousand islands and islets. How many of these
have ever been searched for insects? With the case of Lundy
Island before us, who shall say that there is not yet scope for
extensive and interesting investigations into the British fauna
and flora 2
ISLAND LIFE.
CHAPTER XVn.
BORNEO AND JAVA.
Potiiion anil Physicnl Fealurea of Borneo.— Zoolagicnl Fonttires of Bnrreo; Mnm-
mnlia.— Birds.— Tlie Afflnities of tiie Borncan ynuna.-Jnva, ils Piisiiion and
I'hj'iicnl Features. ^-General Clinracier of the Fauna of Java. — DUTerenciM be-
tivean iheFanim of Jnvn mid (hot of ilia otlicr Malay iBlnnds.— Special Rclalioiis
ofllie Jaran Fauna to thai of ibe Asiatic Conlinont. — Fa» Geographical Cltangee
ofjavnnnil Borneo. — TliePliilippine islands, — Concluding RcoiarksoD iIibMoIbj
As a representative of reccut continental islands situated in
tlio tropics, we will taiic Borneo, since, although perhuiis not
much more ancient than Great Britain, it presents a consider-
able amount of Epeciality, and, in its relations to the surround-
ing islands and the Asintie continent, offers us some problems
of great interest and considerable difficulty.
The accompanying map ebowB that Borneo ia situated on the
eastern side of a submarine bauk of enormous extent, being
about 1200 miles from north to south, and 1500 from east to
west, and embracing Java, Sumatra, and the Malnj' Peninsula.
This vast area is all included within the 100-fathom line ; but by
far the larger part of it — from the Gnlf of Siam to the Java
Sea — is under fifty fathoms, or about the same depth as the sea
that separates our own island from the continent. The distance
from Borneo to the southern extremity of the Malay Peninsula
is about 350 miles, and it is nearly as far from Sumatra and
Java, while it is more than 600 miles from tlie Siamese Penin-
sula, opposite to which its long northern coast extends. There
18,1 believe, nowhere else npon the globe an island bo far from
a continent, yet separated from it by so shallow a sea. Recent
changes of sea and land must have occurred here on a grand
scale, and this adds to the interest attaching to the study of tbia
large island.
i
344
ISLAND LIFE.
Tlie internal geogrnpliy of Borneo is Bomewliat peculinv. A
large portion of its surface is lowland, consisting of great allu-
vial valleys wUieli penetrate far into the interior ; while the
]Doiintaing, except in the north, are of no great elevation, and
there are no extensive plateaus. A subsidence of 500 feet
would allow the sea to fill the great valleys of the Pontianak,
Banjerninssin, and Coti rivci-s, almost to the centre of the isl-
and, greatly reducing its extent, and causing it to resemble in
form the island of Celebes to tlic east of it.
In geological structure Borneo is thoroughly continental, pos-
eessing formations of ail ages, with basalt and crystalline rocks,
bnt no recent volcanoes. It possesses vast beds of coal of Ter-
tiary age; and these, no less than the great extent of alluvial
deposits in its valleys, indicate great changes of level in recent
geological times.
Having thus briefly indicated those physical features of Bor-
neo which are necessary for our iuriuiry, let us turn to the or-
ganic world.
Neither as regards this great island nor those which surround
it have we the amount of detailed information in a convenient
form tliat is required for a full elucidation of its past history.
We have, however, a tolerable acquaintance with the two higher
groups — mammalia and birds — both of Borneo and of all the sur-
rounding countries, and to these alone will it be necessary to
refer in any detail. The most convenient coui-sc, and that which
will make the subject easiest for the reader, will be to give,
first, a connected sketch of what is known of the zoology of
Borneo itself, with the main conclusions to which they point;
and then to discuss the mutual relations of some of the adjacent
islands, and the series of geographical changes that seem re-
quired to explain them.
ZooLOOtCAL FeATDBEB OF BoH.VEO.
Mammalia. — About ninety-six species of mammalia have
been discovered in Borneo, and of these nearly two thirds are
identical with those of the surronnding countries, and nearly
one half with those of the continent. Among these are two
lemurs, three civets, three cats, three deer, the tapir, the ele-
Chap. XVIL]
BORNEO AND JAVA.
345
phant, and several squirrels — an assemblage which could cer-
tainly only have reached the country by land. The following
species of mammalia are supposed to be peculiar to Borneo :
QUADRUMANA.
16. Sciuras ephippium.
1.
Simia morio. A small orang-outang
17. *'
pluto.
with large incisor teeth.
18. "
macrotis.
2^
Hylobates concolor.
19. **
Sarawakensis.
3.
Kasalis larvatus.
20. "
Bomeonensis.
4.
Semnopitliecus rubicundus.
21.
rufogularis.
5.
*' chiysomelos.
22. '*
atricapillns.
G.
*' frontatus.
23. "
rufogaster.
7.
Macacos melanotus.
24. Acantbion crassispinis.
Cabnivora.
25. Trichys lipara.
8.
Cvnogale Bennettii.
iNBECnVORA.
9.
10.
11.
12.
m ^9
Paradoxarus stigmaticas.
Ilerpestes semitorquatus.
** brachyuras.
Felis badia.
26. Tupaia splendidula.
27. " minor (Gunther,
1876, p. 426).
28. Dendrogale miirina.
P. Z, o.|
13.
Lutra Lovii (Gtinther, P. Z. 5., 1876,
29. Ptilocerus Lowii.
p. 736).
Chiroftbba.
Unoulata.
30. Phyllorina dorite.
14.
Sus barbatas.
31. Vesperugo stenoptems.
32.
donaB.
RODENTIA.
33. "
tjlopus.
15.
Pteromys plisomelas.
34. Tapliozous aflSnis.
Of the thirty-four peculiar species here enumerated, it is prob-
able that when they are more carefully studied some will be
found to be identical with those of Malacca or Sumatra ; but
there are also four peculiar genera which are less likely to be
discovered elsewhere. These are Nasalis, the remarkable long-
nosed monkey ; Cynogale, a semi-aquatic civet ; Trichys, a tail-
less porcupine ; and Ptilocerus, a feather-tailed arboreal insecti-
vore. These peculiar forms do not, however, imply that the
separation of the island from the continent is of very ancient
date, for the country is so vast, and so much of the connecting
land is covered with water, that the amount of speciality is
hardly, if at all, greater than occurs in many continental areas
of equal extent. This will be more evident if we consider that
Borneo is as large as the Indo-Chinese Peninsula, or as the In-
dian Peninsula south of Bombay ; and if either of these countries
were separated from the continent by the submergence of the
846
ISLAND LIFE.
m
whole area north of it as far as the JlimalayRB, it would be
foand to contain about as many peculiar geiierii anil species
as Borneo actually does now. A more decisive test of the lapee
of time since the separation took place is to be found in the
presence of a number of representative species closely allied
to those of the surrounding countries, such a& the tailed mon-
keys and the numerous squirrels. These, however, are best seen
anioug the birds, which have been more thoronghly collected
and more carefully studied than the mammalia.
Birds. — About 400 species of birds are known to inhabit
Borneo, of which 340 are land birds. There are about 70 pe-
culiar species; and, according to Count Salvadori, 34 of these
(39 with Liter additions) are 'very distinct forms, while no less
than 31 are slight moditications of species found in Sumatra or
the Malay Peninsula. The following are the species of birds
considered by Count Salvadori to be peculiar to Borneo, with
the addition of a few species since added :
t Upeda.
\. IndlcAior Brchipelngiis.
!. Ueleracocrjx nuglecliiB.
I. Cevx Slinrpei.
,. ■'• Uillnj-iii.
UtptHeatanti SpKia.
m\ax <OivlbJ.
I 1. Kiiiox BomDOTieniiis.
I 2. CiCGuba leptaeraiDmici.
.EM ID A (Barbcts).
I 8. CholorcB chrfsopalB.
I 4. CulorbamlihuB futigiDosas.
E <\Vooiip8ckerii).
Ill, Ueniilci|ihui Ifisclieii.
G. JimgipicDS aurnntiivcniriii.
7. Micropternus bndiiuus.
[,in.« (Cuckoos).
I B, Bbcil>o<lrtes Bonieoneiitis.
(Kingflsben).
I II. BnlracliMtomiti nilfiperaiu.
Caphiuclqidx (Go«igncker>).
. CnprJmulgui arundinncetu. IBS. Cnprimultfiia Bulweri,
Chap. XVII.]
BORNEO AND JAVA.
347
FnwT flxiirvB.
Very Diatinci Species.
Seookd Skbiks.
Representative Species.
8. Delichon dasrpiis.
IIlRUNDINIDJC (Swallows).
I
MusciCAPiDA (Flycatchers).
9.
10.
11.
12.
Cvornis rafifrons.
*' tarcosa.
*^ beccariana.
Schwaneria csrolata.
13. Artnmus clemencia:.
Ahtamida (Swallow-shrikes).
I
Laniidje (Shrikes).
13. VolvociTora SchicrbraDdi.
14. Lnnius Schwnneri.
15. Pityriasis gymnocephala.
NKCTARiNiiDiE (Sunbirds).
IG. Arnchnothera crassirostris. |
DiCEiDJC (Flower-peckers).
14. PrioDochilos xanthopygius.
17. Zosterops melanura.
15. Diceam nigrimentum.
IG. Zosterops panrala.
PrcNONOTiDJC (Bolbuls).
18.
10.
20.
21.
Pycnonotiis Gourdinii.
Criniger Diardi.
Finschii.
4i
Tiirdinus leucogramroiciis
Setaria pectoralis.
ciiiereicapilla.
((
TiMALiiDJc (Babblers).
17. Pomatorhinus Bomeonensis.
1 8. Mixomis Bomeonensis.
19. Drymocataphus capistratioides.
20. Brachypterjx umbratilis.
21. Malacocincla nxfiventris.
PiTTiDjE (Pittas).
24.
Pitta BertflB.
22. Pitta granatina.
2r».
** arcuata.
23. ** Schwaneri.
20.
" Baudii.
24. ** Usheri.
Stlviidjs
(Warblers).
27.
Abrornis Schwaneri.
28.
Prinitt superciliaris.
25. Orthotomus Bomeonensis.
29.
Calamodyta donaj.
30.
Kittaciiiela Stricklandi.
2G. Kittacincla suavis.
CoBViDJE (Crows and Jays).
27. Dendrocitta cinerascens.
28. Platysmurus aterriroos.
ISLAND LIFE,
31. Mii'nfraBoi
H'preaeatative Sprcia.
PuAaiiNiuf (PlieoBanta).
33. I'oljplectron cm[j1ianuiii (Itlnnd of
I'ainwnn).
31. P. SchlBlcrranplieri.
5'>. LobiqphaEis Bulweri.
SC. " caauineicouiln.
no. Eoploe.
SI.
IUllid.g (Itnils).
37. Itiilliini ruflgenis. |
Tetbaomu* (rarlriiigea, etc.).
3S, IletnftlOL'lyx annguinicepa. I
39. Bnmbusicola h.'porTllira. |
Representative forms of tho eaiiie character as these are, no
doubt, foil lid in all extensive continental areas, but they are rarely
6o numerous. Thus, in Mr. Elwes's paper on tlie " Bietribntion
of Asiatic Bii-ds," lie states that 12.5 per cent, of tho land birds
of Burniah and Tenasserini are peculiar species, whereas wo find
that in Borneo they are about 20 per cent., and the differeneo
may fairly be imputed to the greater proportion of slightly
modified representative epecies due to a period of complete
iGoIntion. Of jieculiar genera, the Indo-Chinese Peninsula has
one — AmpelicepB, a i-emarkable yellow-crowned starling, with
bare pink-colored orbits ; while two others, Temnarns and Cryp-
sirliina — singular bii-ds nllietl to the jays — are found in no otlier
part of tho Astatic continent, though they occur in some of the
Malay Islande. Borneo has three irecnliar genera — Schwaneria,
a flycatcher; Ileiuatortyx, a crested partridge ; andLobiophasis,
H pjieaeant hardly distinct from Euplocamus; while two others, «
Pityriasis, an extraordinary bare-headed bird between a jay and
a shrike, and Carpococcyx, a pheasant-like ground-cuckoo, for-
merly thought to be peculiar, arc said to have been discovered
also in Sumatra.
The insects and land shells of Borneo and of the surrounding
countries are too imperfectly known to enable iisto arrive at any
Chap. XVU.] BORNEO AND JAVA. 349
accurate results with regard to their distribution. They agree,
however, with the birds and mammals in their general approxi-
mation to Malayan forms, but the number of peculiar species is
perhaps larger.
The proportion here shown of one tliird peculiar species of
mammalia to about one fifth peculiar species of land birds teach-
es us that the possession of the power of flight only affects the
distribution of animals in a limited degree, and gives us confi-
dence in the results we may arrive at in those cases where we
have, from whatever cause, to depend on a knowledge of the
birds alone. And the difference we here find to exist is almost
wholly due to the wide range of certain groups of powerful
flight — as the birds of prey, the swallows and swifts, the king-
crows, and some others ; while the majority of forest birds ap-
pear to remain confined, by even narrow watery barriers, to al-
most as great an extent as do the mammalia.
The Affinities of the Bornean Fauna. — The animals of Borneo
exhibit an almost perfect identity in general character, and a
close similarity in species, with those of Sumatra and the Malay
Peninsula. So great is this resemblance that it is a question
whether it might not be quite as great were the whole united ;
for the extreme points of Borneo and Sumatra are 1500 miles
apart — as far as from Madrid to Constantinople, or from Bombay
to Rangoon. In this distance we should expect to meet with
many local species, and even representative forms, so that we
hardly require a lapse of time sufficient to have produced specific
change. So far as the forms of life are concerned, Borneo, as an
island, may be no older than Great Britain ; for the time tliat has
elapsed since the glacial epoch would be amply sufficient to pro-
duce such a redistribution of the species, consequent on their
mutual relations being disturbed, as would bring the islands into
their present zoological condition. There are, however, other
facts to be considered, which seem to imply much greater and
more complex revolutions than the recent separation of Borneo
from Sumatra and the Malay Peninsula, and that these changes
must have been spread over a considerable lapse of time. In or-
der to understand what these changes probably were, we must
give a brief sketch of the fauna of Java, the peculiarities of
DLUTD UFB.
tr-
whieh introdace a new element into tlie qoestion tc hare to
Jata.
Tbe rich and beantifal island of Java, interesting alike to tlie
poHtician, the geograplier, and the natnralist, i& more eepeciallr
attractive to the fitndent of geographical dUtribotion, because it
fnroiehes him with home of tlie most cnrioas anomalies and dif-
ficult probleRU in a place where each wonld be least expected.
As Java furuia with Hninatra one almost nnbrokcn hoc of vol-
canoes and volcanic moimtains, iuterrnpted only by the narrow
Strait of 8unda, wo ehould naturally expect a close resemhlance
between tlic productions of the two islands. Bat in point of fact
there it a much greater difference between tlicm than between
Sumatra and Borneo, eo much farther apart, and &o very unlike
in pliyHical features. Java differs from the three great land
maeseii Borneo, Snmatra, and the Malay I'cninEnla far more
tlian either of these does from each other; and this is the firet
anomaly we encounter. But a more serious difficulty than this
remaiUA to be stated. Java has certain close rescrahlunccs to the
Siamese Beninaiila, and also to the Himalayas, which Borneo and
Huinnti'ii (lu not exhibit; and, looking at the relative position of
tlicBC lands respectively, this seems most incomprehensible. In
order fully to appreciate tlie singalarity and difficulty of the
problem, it will be necessary to point out the exact nature and
umunnt of tlieso peculiarities in the fauna of Java.
Oeiieral Charactr^r of the Fauna of Java.~li we were only
to take account of tlic numlier of peculiar species in Java, and
tlio relations of its fanna generally to that of tho surrounding
lands, wo miglit pass it over as a less interesting island than Bor-
neo or Sumatra. Its matnmnlin (ninety species) arc nearly as nu-
merous as those of Borneo, bu*. iirc apparently less peculiar, none
of tlio genera niid only five or six of tlie species being confined
to ttio island. In land birds it is decidedly less ricli, having only
270 species, (if which 40 are peculiar, and only one or two be-
long to peculiar genera; so tliat here again the amount of spe-
ciality is less tliHu in lioriieo. It is only when wo proceed to an-
alyze tho species of the Javan fauna, and trace tlicir distribution
and affinities, tlmt wo disi^over its interesting nature.
CBAt. XVU.]
BOBNEO ASD JAVA.
351
Dijft-iVHce between i/ie Fauna of Java, and that of the other
Great Maiay Islands. — Comparing tlie fuiuia of Juva witli that
which may be called the typical Malayan fauna as exiiibited in
Borneo, Sumatra, and the Malay Peninsula, we find tJie follow-
ing differences. No tcss than thirteen genera of mammalia,
each of which is known to inhabit at least two, and generally
all three, of the above-named Malayan conntrice, are yet totally
absent from Java ; and they include snch important forms as the
elephant, the tapir, and the Malay bear. It cannot be said tliat
this difference depends on imperfect knowledge, for Java is one
of the oldest liiiropean settlements in the East, and lias been
explored by a long succession of Dutch and EngliBh natnralists.
Every part of it is thoroughly well known, and it would be al-
most as difficult to find n new mammal of any size in Europe as
in Java. Of birds there are twenty-five genera, all typically
Malayan, and occurring at least in two, and for the most part in
all three, of the Malay countries, which are yet absent from Java.
Most of these are large and conspicuous forms, such as jays,
gapers, bee-eaters, woodpeckers, hurnbills, cuckoos, parrots, pheas-
ants, and partridges, as impossible to have remained undiscover-
ed in Java as the large marauialia above referred to.
lie^ides these absent genera, there are some curious illnstra-
tloiis of Javau isolation in the species: there being several eases
in which the same species occurs in all three of the typical Ma-
lay countries, while in Java it is represented by an allied species.
Such appear to be the Malayan monkey, StminopiUwcua crista-
tu8, replaced in Java by S. maurui ; and the large Malay deer,
/ium equinus, represen ted in Java by H. hippeJaphug. Among
birds there are more numerous examples, no less than seven
species which are common to the three great Malay countries
being represented in Java by distinct but closely allied species.
From these facts it is impossible to doubt that Java has had a
history of its own, quite distinct from that of the other portions
uf the Malayan area.
Special Jirl-ationa of tfie Jatian Fauna to that of ths Asiatic
Contitt/mt. — These relations are indicated by comparatively few
examples, but they are very clear and of great importance.
Among uiauinmlia, the gcuus Helictis is found in Java, but in no
ISLAND UFK.
[Pah IL
other Malay country, tliougli it inliabita also Nortli ludia ; while
two Bpecies, Rhinoceros Javanicns and Zfpu3 Kurffmaj&TcinttWiia
of Indo-Chinese countries and Java, but not of typical Malaya.
Iq birdfi, there are three genera— Zootliera, ITotodelu, and Cryp-
sirhina — which inhabit Java and Indo-China; while four others
— Brachypteryx, AUotrina, Cochoa, and Pealtria — inhabit Java
and the llimalayaa, but no intervening country. There are also
two species of birds — a trogon (//a/ymcfc^ Oreskioa) and the Jav-
anese peacock {Pavo muticm) — which inhabit only Java and the
Indo-Chinese Peninsula.
Here, then, we find a series of remarkable similarities between
Java and the Asiatic continent, quite independent of tlie typical
Malay countries, Borneo, Sumatra, and the Malay rciiinsiiln,
which latter have evidently formed one connected land, and thus
appear to preclude any independent union of Java and Siam.
The great difficulty in explaining these facts ie that all the
required clianges of sea and land must have occnrred within the
period of existing species of mammalia. Sumatra, Borneo, and
Malacca are, aa we have seen, almost precisely alike as regards
their species of mammals and birds; while Java, though it dif-
fers from them in so eurions a innnner, has no greater degree of
speciality, since its species, when not Malayan, are almost all In-
dian or Siamese.
There is, however, one consideration which may help us over
this difficulty. It seems highly probable that in tho equatorial
regions species liave changed less rapidly than in the north tem-
perate zone, on account of tho equality and stability of the equa-
torial climate. "We liave seen, in Chapter X., how important an
agent in producing extinction and modification of species must
have been the repeated changes from cold to warm and from
warm to cold conditions, with the inevitable migrationB and
crowding-together that must have been their necessary conse-
quence. But in the lowlands near the equator these changes
would he very little felt, and thus one great cause of specific
modification would be wanting. Let us now see whether wc
ran sketch out a series of not iraprobabJo changes which may
have brought about the existing relations of Java and Borneo to
the continent.
Chap. XVII.] BOKNEO AND JAVA. 353
Past Geographical Changes of Java and Borneo, — Altliougli
Java and Siiiimtra are mainly volcanic, they are by no means
wholly 80. Sumatra possesses in its great mountain masses
ancient crystalline rocks with much granite, while there are ex-
tensive Tertiary deposits of Eocene age, overlying which are
numerous beds of coal now raised up many thousand feet above
the sea.* The volcanoes appear to have burst through these
older mountains, and to have partly covered them, as well as
great areas of the lowlands, with the product of their eruptions.
In Java either the fundamental strata were less extensive and
less i*aised above the sea, or the period of volcanic action has
been of longer duration ; for here no crystalline rocks have been
found except a few boulders of granite in the western part of
the island, perhaps a relic of a formation destroyed by denuda-
tion, or covered up by volcanic deposits. In the southern part
of Java, however, there is an extensive range of low mountains,
about 3000 feet high, consisting of basalt with limestone appar-
ently of Miocene age.
During this last-named period, then, Java would have been
at least 3000 feet lower than it is now, and such a depression
would probably extend to considerable parts of Sumatra and
Borneo, so as to reduce them all to a few small islands. At
some later period a gradual elevation occurred which ultimately
united the whole of the islands with the continent. This may
have continued till the glacial period of the Northern Hemi-
sphere, during the severest part of which a few Himalayan spe-
cies of birds and mammals may have been driven southward,
and ranged over suitable portions of the whole area. Java was
then separated by subsidence, and these species became im-
prisoned there ; while those in the remaining part of the Ma-
layan area again migrated northward when the cold had passed
away from their former home, the equatorial forests of Borneo,
Sumatra, and the Malay Peninsula being more especially adapted
to the typical Malayan fauna, which is there developed in rich
profusion. A little later the subsidence may have extended
farther north, isolating Boraeo and Sumatra, but probably leav-
* *' On the Geology of Sumatra," by M. R. D. M. Verbeck, Gtolwjical Mag,, 1877.
23
ing the Malay Peninaula ns a ridge between tbem as far as the
islands of Banca and Biliton. Otiier sliglit elwngea of diinato
followed, when a further siibsiJence separated these last-named
islands from the Malay Peninsula, and left them with two or
three species which hare since become elightty modified. Wo
may thus explain how it is that a species is sometimes common
to Sumatra and Borneo, while the intorveniug island (Banca)
possesses a distinct form.'
In my " Geographical Distribution of Animals," Vol. I., p. 357,
I have given a somewhat different hypothetical explanation of
the relations of Java and Borneo to the continent, in which I
took account of changes of land and sea only; hut a fuller con-
Bidciution of the influence of changes of climate on the migra-
tion of animals lias led me to the much simpler, and, I think,
more probable, explanation above given. The amount of the re-
lationship between Java and Siam, as well as of that between
Java and the Himalayas, is too small to be well accounted for
by an independent geographical connection in which Borneo
and Sumatra did not take part. It is, at the same time, too dis-
tinct and indisputable to be ignored; and a change of climate
which shonld drive a portion of the Himalayan fauna sooth-
ward, leaving a few species in Java (from which they conld not
return, owing to its subsequent isolation by eubsidencc), seems to
bo a cause exactly adapted to produce the kind and amount of
affinity between these distant countries that actually exist.
The Phillj^ine Inlands. — A sufficiently detailed account of
tlie fauna of these islands, and their relation to the countries
which form the subject of this chapter, has been given in my
" Geographical Distribution of Animals," Vol. I., pp. 34r}-349 ;
hilt since that time considerable additions have been made to
their fauna, and these have had the effect of diminishing their
isolation from the other islands. Si-x genera have been added
to the terrestrial mammalia — Crocidura, Felis, Ti-agnlus, Hystrix,
Fteromys, and Mus, as well as two additional scjuirrels; while
the black ape {VijtwpilAi'-nui niffer) has been struck out as not
' Pilta mffiarhgnrhui (Baava), nl1i<Ml to P, &i-nrAyiini>(DornEO. Sumulrn, Mulaccn).
nnd Pilla Baitgknn<it (ISnncn). iilliod to /*. lordidiu {Womv> lint] Siimntrn).
Chap. XVII.] THE nilLIPPINES. 355
inhabiting tlie Pliilippines. This brings the known mammah'a
to twenty-one species, and no doubt several others remain to be
discovered. The birds liavo been increased from 219 to 288 spe-
cies, and the additions include many Malayan genera which were
thought to be absent. Such are Phyllornis (green bulbnl) ; Eu-
rylcemus (gaper), Malacopteron, one of tlie babblers ; and Crini-
ger, one of the fruit-thrushes ; as well as Batrachostomus, the
frog-mouthed goatsucker; There still remain, however, a large
number of Malayan genera absent from the Philippines, while
there are a few Australian and Indian or Chinese genera which
are not Malayan. We must also note that about nine tenths of
the mammalia and two thirds of the land birds are peculiar spe-
cies, a very much larger proportion than is found on any other
Malay island.
The origin of these peculiarities is not difficult to trace. The
Philippines are almost surrounded by deep sea, but are connected
with Borneo by means of two narrow submarine banks, on the
northern of which is situated Palawan, and on the southern the
Sooloo islands. Two small groups of islands, the Bashees and
Babuyanes, have also afforded a partial connection with the con-
tinent by way of Formosa. It is evident that the Philippines
once formed part of the great Malayan extension of Asia, but
that they were separated considerably earlier than Java; and
liaving been since greatly isolated and much broken up by vol-
canic disturbances, their species have, for the most part, become
modified into distinct local species. They have also received a
few Chinese types by the route already indicated, and a few
Australian forms, owing to their proximity to the Moluccas.
The reason of their comparative poverty in genera and species
of the higher animals is tliat they have been subjected to a great
amount of submersion in recent times, greatly reducing their
area, and causing, no doul)t, the extinction of a considerable por-
tion of their fauna. This is not a mere hypothesis, but is sup-
ported by direct evidence; for I am informed by Mr. Everett,
who has made extensive explorations in the islands, that almost
everywhere are found large tracts of elevated coral reefs con-
taining shells similar to those living in the adjacent seas — an in-
disputable proof of recent elevation.
356 ISLAND LIFE. [Part IL
Concluding Remarks cm the Malay Islands. — This completes
our sketch of the great Malay islands, the seat of the typical
Malayan fauna. It has been shown that the peculiarities pre-
sented by the individual islands may be all sufficiently well ex-
plained by a very simple and comparatively unimportant series
of geographical changes, combined with a limited amount of
change of climate towards the northern tropic. Beginning in
late Miocene times, when the deposits on the south coast of Java
were upraised, we suppose a general elevation of the whole of
the extremely shallow seas uniting what are now Sumatra, Java,
Borneo, and the Philippines with the Asiatic continent, and
forming that extended equatorial area in which the typical
Malayan fauna was developed. After a long period of stability,
giving ample time for the specialization of so many peculiar
types, the Philippines were firet separated ; then at a considera-
bly later period Java ; a little later Sumatra and Borneo ; and
finally the islands south of Singapore to Banca and Biliton. This
one simple scries of elevations and subsidences, combined with
the changes of climate already referred to, and such local eleva-
tions and depressions as must undoubtedly have occurred, ap-
pears sufficient to have brought about the curious, and at first
sight puzzling, relations of the faunas of Java and the Philip-
pines as compared with those of the larger islands.
We will now pass on to the consideration of two other groups
which offer features of special interest, and which will complete
our illustrative survey of recent continental islands.
CuAP.XVni.] JAPAN AND FORMOSA. 357
CHAPTER XVIII.
JAPAN AND FORMOSA.
Japnn : its Position nnd Physical Features. — Zoological Features of Japan. — Mam-
malia.— Birds. — Birds Common to Great Britain and Japan. — Birds Peculiar to
Japan. — Japan Birds Recurring in Distant Areas. — Formosa. — Physical Features
of Formosa. — Animal Life of Formosa. — Mammalia. — Land Birds Peculiar to
Formosa. — Formosan Birds Recurring in India or Malaya. — Comparison of
Faunas of Hainan, Formosa, and Japan. — General Remarks on Recent Continen-
tal Islands.
Japan.
The Japanese Islands occupy a very similar position on the
eastern shore of the great Euro- Asiatic continent to that of the
British Islands on the western, except that they are about six-
teen degrees farther south, and, having a greater extension in
latitude, enjoy a more varied as well as a more temperate cli-
mate. Their outline is also much more irregular and their
mountains loftier, the volcanic peak of Fnsiyama being 14,177
feet high ; while their geological structure is very complex, their
soil extremely fertile, and their vegetation in the highest degree
varied and beautiful. Like our own islands, too, they are con-
nected with the continent by a marine bank less than a hundred
fathoms below the surface — at all events, towards the north and
south ; but in the intervening space the Sea of Japan opens out
to a width of 600 miles, and in its central portion is very deep ;
and this may be an indication that the connection between the
islands and the continent is of rather ancient date. At the
Strait of Corea the distance from the mainland is about 120
miles, while at the northern extremity of Yesso it is about 200.
The island of Saghalie'n, however, separated from Yesso by a
strait only twenty -five miles wide, forms a connection with
Amoorland in about 52° N. lat. A southern warm current flow-
ing a little to the eastward of the islands ameliorates their cli-
mate much in the same way as the Gulf Stream does ours, and.
Chap. XVIII.] JAPAN AND FORMOSA. 359
added to their insular position, enables them to support a more
tropical vegetation and more varied forms of life than are found
at corresponding latitudes in China.
Zoological Featurea of Japan, — As we might expect from the
conditions here sketched out, Japan exhibits in all its forms of
animal life a close general resemblance to the adjacent conti-
nent, but with a considerable element of specific individuality ;
while it also possesses some remarkable isolated groups. It also
exhibits indications of there having been two or more lines of
migration at different epochs. The majority of its animals are
related to those of the temperate or cold regions of the conti-
nent, either as identical or allied species; but a smaller number
have a tropical character, and these have in several instances no
allies in China, but occur again only in Northern India or the
Malay Archipelago. There is also a slight American element
in the fauna of Japan, a relic probably of the period when a
land communication existed between the two continents over
what are now the shallow seas of Japan, Ochotsk, and Kamt-
schatka. We will now proceed to examine the peculiarities and
relations of the fauna.
Mammalia, — The mammalia of Japan at present known are
forty in number; not very many when compared with the rich
fauna of China and Manchuria, but containing monkeys, bears,
deer, wild goats and wild boars, as well as foxes, badgers, moles,
squirrels, and hares, so that there can be no doubt whatever that
they imply a land connection with the continent. No complete
account of Japan mammals has been given by any competent zo-
ologist since the publication of Von SieboWs " Fauna Japonica"
in 1844 ; but by collecting together most of the scattered observa-
tions since that period the following list has been drawn up, and
will, it is hoped, be of use to naturalists. The species believed
to be peculiar to Japan are printed in italics. These are very
numerous, but it nmst be remembered that Corea and Manchu-
ria (the portions of the continent opposite Japan) are compara-
tively little known, while in very few cases have the species of
Japan and of the continent been critically compared. Where
this has been done, however, the peculiar species established by
the older naturalists have been in many cases found to be correct.
360 ISLAND LIFE. [Fast II
List of the Mammalia of the Japaxese Islands.
1. Macacta sjteciosus. A monkej with rudimentary tail and red face, allied to the
Barbary ape. It inhabits the island of Niphon up to 41° N. lat, and has
thus the most northern range of any living monkey.
2. Pteropus dasymallu$, A peculiar fruit-bat, found iu Kiusiu Island only (lat.
9^"* N.), and thus ranging farther north of the eqnator than any other species
of the genus.
8. Rhinoloplius ferrnm-eqninum. The great horseshoe -bat, ranges from Britain
across Europe and temperate Asia to Japan. It is the R. nippon of the ** Fau-
na Japonica,'* according to Mr. Dobson^s '* Monograph of Asiatic Bats."
4. B. minor. Found also in Burmali, Yunnan, Java, Borneo, etc.
5. Vesperugo pipistrellus. From Britain across Europe and Asia.
6. ** abramus. Also in India and China.
7. *' noctula. From Britain across Europe and Asia.
8. '* molossus. Also in China.
9. Vespertilio capaccinii. Philippine Islands and Italy. This is V, macrodactylus
of the ** Fauna Japonica," according to Mr. Dobson.
10. Miniopterus Schreibersii. Philippines, Burmah, Malay Islands. This is Vesper'
tiiio blepotis of the ** Fauna Japonica."
11. Talpa wogura. Closely resembles the common mole of Europe, but has six in-
cisors instead of eight in the lower jaw.
1 2. Urotrichua ta/poides. A peculiar genus of moles confined to Japan and the
northwest const of North America. The American species has been numetl
Urotrichus Gibsii ; but Mr. Lord, after comparing the two, says that he *' can
find no difference whatever, cither generic or specific. In shape, size, and col-
or they are exactly alike.
13. Sorex mvosurus. A shrew, found also in India and Mulnva.
1 4. Sorex dzi-nezumi,
ir». ** umbrinus.
ly. " plahjcephnlus,
17. Ursns arctos, var. A peculiar variety of the European brown bear, which in-
habits also Anioorland and Kamtschatka. It is the Ursusferox of the *' Fau-
na Japonica."
18. Ur&us Japonirus. A peculiar ppccies allied to the Himalayan and Formosan spe-
cies. Named U. Tibetanus in the *' Fauna Japonica."
10. Meles anakuma. Differs from the European and Siberian badgers in the form
of the skull.
20. Mustela brachynra. A peculiar marten found also in the Kurilc Islands.
21. ** rnelampus. The Japanese sable.
22. ** Japonica, A peculiar marten (see Proc. Zool. Soc.y 18Cr», p. 104).
23. ** Sibericus. Also Siberia and China. This is the M. italsi of the
** Fauna Japonica," occording to Dr. Gray.
24. Lutronectes WInteleyi. A new genus and species of otter {Proc. Zool. Soc.^
18G7, p. 180). In the *' Fauna Japonica" named Lulra vit/garis.
25. Enhydris marina. The sea-otter of California and Kamtschatka.
26. Cam's hodophylax. According to Dr. Gray, allied to Cuon Sumatranus of the
Chap.XVIII] japan AND FORMOSA. 361
Malaj Islands, and C, alpinm of Siberia, if not identical with one of them
{Proc, ZooL Soc.f 1868, p. 600).
27. Vulpes Japonica, A peculiar fox. Cams vulpcs of ** Fauna Japonica."
28. Nyctereutes procyonoidcs. The raccoon-dog of Northern China and Amoorland.
29. Lepus hrachyurus, A peculiar hare.
30. Sciunts lis. A peculiar squirrel.
31. Pteromys leucogenys. Tlie white-cheeked flying squirrel.
32. *' momoga. Perhaps identical with a Cambojan species {Proc. ZooL
i&)c.,1861,p.l37).
33. MyoTus Japonicus. A peculiar dormouse. Af. elegans of the ''Fauna Japoni-
ca ;" M. Javanicusj Schinz (*' Synopsis Mammalium," ii., p. 530).
34. Mus argenteus. China.
35. *' molossinus.
36. ** nezumi.
37. ** speciosus.
38. Cervus sika. A peculiar deer allied to C pseudaxis of Formosa and C. Man'
churicus of Northern China.
3D. Nemorhedus crispa. A goat-like antelope allied to N. Sumatranus of Sumatra,
and N, Swinhoei of Formosa.
40. Sm leucomystax. A wild-boar allied to S. Taivanus of Formosa.
We thus find that no less than twenty-six out of the forty
Japanese mammals are peenliar ; and if we omit the aerial bats
(nine in number) as well as the marine sea-otter, we shall have
remaining only thirty strictly land mammalia, of which twenty-
five are peculiar, or five sixths of the whole. Nor does this rep-
resent all their speciality ; for we have a mole differing in its
dentition from the European mole; another closely allied to an
American species ; a peculiar genus of otters ; and an antelope
whose nearest allies are in Formosa and Sumatra. The impor-
tance of these facts will be bestninderstood when we shall have
examined the corresponding affinities of the birds of Japan.
Birds. — Owing to the recent researches of some English resi-
dents, we have probably a fuller knowledge of the birds than of
the mammalia ; yet the number of true land birds ascertained
to inliabit the islands cither as residents or migrants is only one
hundred and sixty-five, which is less than might be expected
considering the highly favorable conditions and the extreme
riches of the adjacent continent — Mr. Swinhoe's list of the birds
of China containing more than four hundred land species, after
deducting all that are peculiar to the adjacent islands. Only
sixteen species, or about one tenth of the whole, are now consid-
362
ISLAND LIFE.
[Pakt II.
ercd to be peculiar to Japan ; but even of these five are classed
by Mr. Seebolira as sub-species or slightly modified forms of
continental birds, so that eleven only are well-marked species,
undoubtedly distinct from those of any other country.
The great majority of the birds are decidedly temperate
forms identical with those of Northern Asia and Europe ; while
no less than forty of the species are also found in Britain, or are
such slight modifications of British species that the difference is
only perceptible to a trained ornithologist. The following list
of the birds common to Britain and Japan is very interesting,
when we consider that these countries are separated by the
whole extent of the European and Asiatic continents, or by al-
most exactly one fourth of the circumference of the globe :
Birds Common to Great Britain and Japan.'
1.
2.
3.
4.
6.
6.
7.
8.
J).
10.
11.
12.
13.
14.
ir..
IG.
17.
18.
19.
20.
Common Creeper {Cert/iia /uinilia-
ris).
Nuthatch (Sitta Europcea),
Coal Tit (Pants ater).
Marsh Tit, siib-sp. (P. Juponlcus).
Long-tailed Tit QAcredula caudata).
Great Gray Shrike (Laniua excubitor).
Nutcracker {Nucifraga caryocatac-
tea).
Carrion-crow (Corvus coroue),
Kavcn (Corvus corar).
Waxwing (Ampelis f/arrulus).
Swallow, sub-sp. (Ilirundo (juttura-
lis).
Sand-martin (Cotyle rijmrid).
n rambling (FringUla uiontijrinrjiUu).
Siskin {Chrysomitris spinus).
Lesser Hcdpole (.I'Jgiot/ius linaria').
Tree-sparrow {Passer ynnntanus).
l*inc-grossbejik {PgiThula enucleatoi').
llced- bunting, t>ub-sp. (Embeviza
pyrrhtilina).
Snow-bunling (Plectrophnnes nivcdis).
Gray AVugtail, sub-sj). {Mutacilla me-
l(nopc).
21. Great Spotted Woodpecker (Picus
major),
22. Great Black Woodpecker (Z)ryocopt«
martius).
23. Cuckoo (Cuculus canorus).
24. Hoopoe (Upupa epops),
25. ]iock-dove (Columba livid).
2G. Hen-harrier (Circus cyuneus).
27. Goshawk (Astur palumbiirius).
28. Sparrow-hawk (Accipiter nisus).
29. Uongij-legged Buzzard (Buteo iago-
pus).
30. Golden Kagle (Aquila chrysnetos).
31. White- tailed Kagle (llaliirtus albi-
cillu).
32. Kestrel (Palco tinnunculus).
33. Hobby (F. subbutco).
34. Merlin (F. astdon).
3."). Teregrine Falcon (F. peregrinus).
3G. Greenland Falcon (F. candicans),
37. Osprey (Pandion haliatus).
38. Eagle-owl (Bubo maximus).
39. Short - eared Owl (Asia acripitri-
nus).
40. Long-eared Owl (^4. otus).
* Extracted from Messrs. Blakision and Fryer's *' Catalogue of Birds of Japan''
(Ibis^ 1878, p. 209), with Mr. Scebohm's additions and correciions (//>m, lf>79,
p. 18).
Chap. XVUL] JAPAN AND FORMOSA. 363
But these forty species by no means fairly represent the
amount of resemhlaiice between Britain and Japan as regards
biiKls; for there are also wrens, hedge-sparrows, gold -crests,
sedge-warblers, pipits, larks, rock-thrushes, jays, and many oth-
ers, which, tliough distinct species from our own, have the same
general appearance, and give a familiar aspect to the ornithol-
ogy. There remain, however, a considerable body of Chinese
and Siberian species, which link the islands to the neighboring
parts of the continent ; and there are also a few which are Ma-
layan or Himalayan rather than Chinese, and thus afford us an
interesting problem in distribution.
The sixteen species and sub-species which are altogether pe-
culiar to Japan are, for the most part, allied to birds of North
China and Siberia, but three are decidedly tropical, and one of
them — a fruit-pigeon {Treron ISieboldi) — has no close ally nearer
than Java and tlie Himalayas. In the following list the affini-
ties of the species are indicated wherever they have been ascer-
tained :
List of the Species op Land Birds Peculiar to Japan.
1. Parus Japonicus, A sub-species of P, palustvis, very like Siberian varieties.
2. ** varlus. Veiy distinct. Its nearest ally is in Formosa.
3. Ifijpsipetes amaurosis. A tropical genus. Allied to species of Sontb China and
India.
4. Garrulus Jajtonicus, Allied to our European jay. In Niphon only.
r>. *' Lidthi. A very distinct and handsome species. (J?'ee Ibisy 1873, p.
478.)
(J. Zosterops Jnponica. Allied to a migratory Chinese species.
7. C/ie/idon BlakUtoni. Allied to C. White'Uyi of North China.
8. Chlorospiza Kawarahiba. Allied to C, Sinica of China and Japan.
I). Emberiza ciopsis. A snl)-specie8 of tlie E. cioides of North China.
10. ** Yessoensis, Allied to the Siberian JET. />aMertna.
1 1. Enspiza variabilis. A very distinct species.
1 2. Picus KisuL'i. Allied to P. pyrjmvtus of Central Asia.
1:J. (mecinus awokera. Allied to (/. canus (North China) and G. riVit/w (Europe).
1 4. Mulleripicus Richardtii. Allied to M. Crawfurdi of Pegu. In Tzus Sima Island
(^Proc. Zool. Soc., 1870, p. 366).
ir>. Treron Sieboldi. Allied to 71 irpA«nura (Himalayas) and 7*. JTor/Aa/st (Java).
1(). Accipiter gularis. A sub-species of the Malayan A. virgatus (also in For-
mosa).
17. Buteo Hcmilasius. A distinct s|>ecies.
1 8. Syr Ilium ru/escens. A sub-species of S. UraUnse of East Europe and Siberia.
su
ISLAND LIFE.
[Part II.
Japa?i Birds li^currinffin Distant Areas. — The most interest-
ing feature in tlie ornithology of Japan is undoubtedly tliu pres-
ence of several speeiea which indicate an alliance with such re-
mote diatriets as tlio Himalayas, the Malay Islands, and Europe.
Among the peculiar species, the most remarkable of this class
are tlie fruit-pigeon of the genus Treron, entirely unknown in
China, but reappearing in Formosa and Japan ; the Hypsipetes,
whose nearest ally is in South China at a distance of nearly five
hundred miles; and the jay {Garndus Jajxmicus), whose close
ally {G.glandurius) inhabits Europe only, at a distance of 3700
miles. But even more extraoi-dinary are the following non-
peeuliar species ; — Spisastus orientalls, a crested eagle, inhabit-
ing the Himalayas, I-'orniosa, and Japan, but unknown in Chi-
na ; Ceryh guttata, a spotted kingfisher, entirely confined to the
Himalayas and Japan ; and JIaleyon Coromanda, a brilliant ret]
kingfisher inhabiting Northern India, the Halay Islands to Cel-
ebes, Formosa, and Japan. We have here an excellent illustra-
tion of the favonible conditions which islands afford both for
species which elsewhere live farther south {^Ilalojon Coromunda),
and for the preservation in isolated colonics of species wliicli
are verging towards extinction ; for such wc must consider the
above-named eagle and kingfisher, both confined to a very limit-
ed area on the continent, bnt surviving in remote islands. The
spotted kingfisher, indeed, affords ns one of the best examples of
that raro phenomenon — a species witli a discontinuous range;
for although an island is considered, for purposes of distribution,
to form part of one continuous ai-ea with the adjacent continent
(us when u species is found in France and Britain, or in Siam
and Borneo, we do not say that the area of distribution is dia-
continunns), yet in this case we have to pass over three thousand
miles of hind after quitting the island, before we come to the
continental portion of the area occupied by the species. Re-
ferring to our account of the birth, growth, and death of a spe-
cies (in Chapter IV.), it can hardly be doubted that the (.Wyi«
fftillata formerly ranged from the Himalayas to Japan, and has
now died out in the intervening area, owing to geogrnphical and
physical changes — a subject which will be better discussed when
we have examined the interesting fauna of the island of Formosa.
Chap. XVIII.] JAPAN AND FORMOSA. 365
The other ordere of animals are not yet sufficiently known to
enable us to found any accurate conclusions upon them. The
main facts of their distribution have already been given in my
" Geographical Distribution of Animals" (Vol. I., pp. 227-231),
and they sufficiently agree with the birds and mammalia in show-
ing a mixture of temperate and tropical forms, with a considerable
proportion of peculiar species. Owing to the comparatively easy
passage from the northern extremity of Japan through the isl-
and of Saghalien to the mainland of Asia, a large number of
temperate forms of insects and birds are still able to enter the
country, and thus diminish the proportionate number of pecul-
iar species. In the case of mammals this is more difficult; and
the large proportion of specific difference in their case is a good
indication of the comparatively remote epoch at which Japan
was finally separated from the continent. How long ago this
separation took place we cannot, of coureo, tell, but we may bo
sure it was much longer than in the case of our own islands, and
therefore probably in the earlier portion of the Pliocene period.
Formosa.
Among recent continental islands, there is probably none that
surpasses in interest and instructiveness the Chinese island
named by the Portuguese Formosa, or the "Beautiful." Till
quite recently it was a terra incognita to naturalists, and we owe
all our present knowledge of it to a single man, the late Mr.
Robert Swinhoe, who, in his official capacity as one of our con-
suls in China, visited it several times between 1856 and 1866,
besides residing on it for more than a year. During this period
he devoted all his spare time and energy to the study of natural
history, more especially of the two important groups, birds and
mammals ; and by employing a large staff of native collectors
and hunters he obtained a very complete knowledge of its fauna.
In this case, too, we have the great advantage of a very thorough
knowledge of the adjacent parts of the continent, in great part
due to Mr. Swinhoc's own exertions during the twenty years of
his service in that country. Wo possess, too, the further advan-
tage of having the whole of the available materials in these two
classes collected together by Mr. Swinhoe himself after full ex-
ISLAND LIFE.
tP*wn.
animation and comparison of epecimene; so that there is prob-
ably no part of the world (if we except Europe, North Araerica,
and Bi'itieh India) of whose warm-blooded vertebrates wo pos-
sess fuller or more accurate knowledge than we do of those of
the coast districts of China and Its islands.'
Physwal Features of Fonnom.— The island of Formosa is
nearly half the size of Ireland, being 230 miles long, and from
twenty to eighty miles wide. It is traversed down its centre by
a fine mountain-range, which reaches an altitude of about SCit'O
feet in the sonth and 12,000 feet in the northern half of the isl-
and, and whose higher slopes and valleys are everywhere clothed
with magnificent forests. It is crossed by the line of the Tropic
of Cancer a little south of its centre; and this position, com-
bined with its lofty mountains, gives it an unusual variety of
tropical and temperate climates. These circumstances are all
highly favorable to the preservation and development of animal
life ; and, from what we already know of its productions, it seems
probable that few, if any, islands of approximately the same size
and equally removed from a continent will be found to equal it
in the number and variety of their higher animals. The outline
map on page 358 shows that Formosa is connected with the
mainland by a submerged bank, the 100-fathoni line including
it along with Hainan to the southwest and Japan on the north-
east ; while the line of 200 fathoms includes also the Madjico-
sima and Loo-choo Islands, and may perhaps mark out proxi-
mately tlio last great extension of the Asiatic continent, the sub-
mergence of which isolated these islands from the mainland.
Animal Life of Formosa., — We are at present acquainted with
35 species of mammalia and 128 species of land birds from
Formosa, 14 of the former and 43 of the latter being pecul-
iar, while the remainder inhabit also some part of the continent
or adjacent islands. This proportion of peculiar species is per^
' Mr. Swhiliue diet] in October, I8TT, at the earlj ige of forty- Ino. Iliii writing!
on naturiil liislar}' nre cliicHy ocnitered ilirough the Tolunm of the Procttdliiy* oflkt
Zooloriieal Snrirli/ nnd 7^" Ibiii tlie kJioId bving iiiinmnriied in liii "Cntslajnis
of ihfl Mammnls of South Cliinn imil FormoKs" (Piik. Xml. Soc,, 18T0, p. GIA), and
bU"Catklogaeoftl)eBir(bofCliiaaaaditilid>u(lB"(/'nici;uB/.At>c,,ie;i,fkitS7).
Chap. XVIIL] JAPAN AND FORMOSA. 367
haps (as regards the birds) the highest to be met with in any
island which can be classed as botli continental and recent, and
this, in all probability, implies that the epoch of separation is
somewhat remote. It was not, however, remote enough to reach
back to a time when the continental fauna was very different
from what it is now, for we find all the chief types of living
Asiatic mammalia represented in this small island. Thus we
have monkeys ; insectivora ; numerous carnivora ; pigs, deer, an-
telopes, and cattle among ungulata; numerous rodents, and the
edentate Manis — a very fair representation of Asiatic mammals,
all being of known genera, and of species either absolutely iden-
tical with some still living elsewhere, or very closely allied to
them. The birds exhibit analogous phenomena, with the excep-
tion that we have here two peculiar and very interesting genera.
But besides the amount of specific and generic modification
that has occurred, we have another indication of the lapse of
time in the peculiar relations of a large proportion of the For-
mosan animals, which show that a great change in the distribu-
tion of Asiatic species must have taken place since the separa-
tion of the island from the continent. Before pointing these
out, it will be advantageous to give lists of the mammalia and
peculiar birds of the island, as we shall have frequent occasion
to refer to them.
List of the Mammalia of Formosa.
{The pemliar species are printed in italics.)
1. Macacus cyclopis, A rock-monkey more allied to M. rhesus of India thnn to
M. Sancti'Johannis of South China.
2. Pteropus formosus. A frait-bat closelr allied to the Japanese species. None
of tlio genus are found in China.
3. Vcsperiigo abramus. China.
4. Ve9pertilio formosus. Black and orange bnt. China.
r>. Nyctinomus cestonii. Large-eared bat. China, South of Europe.
G. Talpo insularis, A blind mole of a peculiar species.
7. Sorcx murinus. Mnskrat. China.
8. ** sp. A shrew, undescribed.
9. firinaceus sp. A hedgehog, undescribed.
10. Ursus Tibetanus. The Thibetan bear. Himalayas and North China.
1 1 . Helictis suhaurantiaca. The orange-tinted tree-civet. Allied to //. Nipalensis
of the Himalayas more than to JI. moschata of China.
12. Martes flavigulfl, var. The yellow-necked marten. India, China.
I3LXSD LITE.
fPittT II.
). Felii macrosoeli:!. Tlia doaded liger of Siam and Matnva.
I. " viverriiin. The Asintic wild-cat. UJivinlnjns nnJ KLilLi::t.'a.
I. " CliinensiB. The Chinese liger-cnL Chinn.
i. VirerHcuIa Malaccensrs. Spotted civet- Chinn, Iildi.i.
r. Pngumii larvata. Gem-faced civet, China.
), Sm TaiBaatit, Allied U> the wild-pig of Jnpan.
). Cervuliis Rcevenii. Reeve's iamitj«e. Cliiiia.
). Crroui pieuilaiii, Formoann gpotted deer. Allied to C, Sika of Jiijinn.
1. " Sieiphofi. Swinhoc'n Itusa deer. Allied to Indian and Mnlnyan apeeJea.
i. NtmoThailif SwinAoti. SuioliMi goat-antelope. Allied to the species o( Su-
matra find Jiipiin.
t. TX<}$ Ciilnon»i«. South Cliinn ivjld-cow.
I. Mus bnndicoin. The hnndiuoot rnt. I'eiiiapa introduced Troin India.
>. " Indicus. Indian rnt.
I. JIfwt coiinga. Spinous country- rat.
'. ■' canaa. Silken counirv-rDt.
\. " losea. Brown con nirj'-rat.
>. Eciiimi ciistaneoTeniri*. Cbeiitint-l>«Uied Rquirrel. Clilnn and llninnn.
I. " MacClvllnndi. MncClellntid's squiiTel. HimolnjaK, Chinn.
. Sfiuropltrua Kateeruis. Small Foimosnii flving-Bquirrol. Allied to S. atbcuiftr
of Nepal.
!. PicFemift prandii. Large red Bying-Bi[uirTel. Allied to llimnliijon and Bor-
nean tpecics. From Noitb FonnoKa-
i, Pltromy pecioralit. While- breasted flving-fquirrel. From South Formosa.
L Lepus Sinensis. Chinese hare. Inhabits Soaih Chinn.
i, Mania Dalmanni. ticoly nnt-eoler. Cliina and the Iliinnlnyiis.
The most interesting anil suggestive feature connected witii
tlicse ForniOEan iiiammale is the identity or affinity of eeveral
of them with Indian or Malayan rather than witli Ciiiiiese spe-
cies. We have the rock-monkey of Formosa allied to tlie rhesiiB
monkeys of India and Bnrniah, not to those of South China and
Hainan, Tlie tree-civet (/leh'ctia eubatirantiaea) and tlie small
flying-sfjuirrel {Sciuropterua Kalf^naia) are both allied to Hima-
layan species. Swinhoe's deer and goat-antelope are nearest to
Malayan species, as are the red and white-breasted flying-sqnir-
rcls; while the fruitrbat, the wild-pig, and the spotted deer are
all allied to peculiar Japanese species. Tlie clouded tiger is a
Malay species unknown in Cliina, while the Asiatic wild-cat is
a native of the Himalayas and Malacca. It is clear, therefore,
that before Formosa was separated from the mainland the above-
named animals or their ancestral types must have ranged over
the intervening country as far as the Himalayas on tiie west,
Chap. XVIII.] JAPAN AND FORMOSA, 369
Japan on the north, and Borneo or the Philippines on tlie south ;
and that, after that event occurred, the conditions were so mate-
rially changed as to lead to the extinction of these species in
what are now the coast provinces of China, while they or their
modified descendants continued to exist in the dense forests of
the Himalayas and the Malay Islands, and in such detached isl-
ands as Formosa and Japan. We will now see what additional
light is thrown upon this subject by an examination of the
birds.
List of tub Land Birds Peculiar to Formosa.
ToRDiDA (Thrushes).
1. Turdus albiceps. Allied to Chinese species.
Stlviid^ (Warblers),
2. Ciiticola volitans. Allied to C. schcenicola of India and China.
3. Uerhivox cantans. Sub-species of U, cantUlans of North China and Japan.
4. Notodela montium. Allied to N, leucura of the Himalayas ; no ally in China.
TiMAUiDJS (Babblers).
r>. Pomatorhinus musicus. Allies in South China and the Himalnvas.
«. *' erylhrocnemis. ** " **
7. Garrulax ntjiceps. Allied to G. albogularis of North India and East Thibet,
not to the species of South Ciiiiia {Q, aannio).
8. Janthocinda pctcilorhyncha. Allied to*/, ccerulata of the Himalayas. None of
tlic genus in China.
9. Trochalopteron Taivanus, Allied to a Chinese species.
10. Alcippe Morrisoniana.\ Near the Himalayan A. Nipalenais. None of tlie genus
11. *' Brunnea. i in China.
12. Siltia auricularis. Allied to the Himalayan S. capislrata. The genus not
known in China.
Panuridje (Bearded Tits, etc.).
] 3. Suthora hulomachus. Allied to the Chinese S. suffusa,
CiKCLiDJS (Dippers and Whistling- thrushes).
14. Mt/iophoneus insularis. Allied to M. Ilorsjiddi of South India.
Parida: (Tit»).
15. Parua insperatus. Sub-species of P. monticola of the Himalayas and East
Thibet.
16. P. castaneoventris. Allied to P. varius of Japan.
Liotrichida (Hill Tits).
17. Liocichla Steerii. A peculiar genus of a specially Himalayan family, quite an-
known in China.
24
370 ISLAND LIFE. [Part U.
Pycnonotid^ (Balbals).
] 8. Pifcnonotut (Spizixos) cinereir.apillus. Very near P, cemitorques of China.
19. Hypsipetes nigerrimus. Allied to H. concolor of Assam, not to H. MacCleilandi
of China.
Oriolid^ (Orioles).
20. Analcipus ardens. Allied to A, Traillii of the Himalayas and Tenasserim.
Campephaoid^ (Caterpillar Shrikes).
21. Graucaius rex-pineti. Closely allied to the Indian G. Macei, No ally in China.
DiCRURiD^ (King Crows).
22. Chaptia Brauniana, Closely allied to C. anea of Assam. No ally in China.
MusciCAPiDA (Flycatchers).
23. Cymmis vivida. Allied to C. rubeculoides of India.
CoRViDA (Jays and Crows),
24. Garrulus Taivanus, Allied to G^. Sinensis of South China.
2r>. Urocissa carulea, A very distinct species from its Indian and Chinese allies.
2G. Dendi'ocitta Formotcf, A sub-species of the Chinese Z>. Sinensis,
Ploceid.k (Weaver Finches).
27. Munia Formotana, Allied to M. rubronigra of India and Burroah.
ALAtiDiOiG (Larks).
28. Alauda Saja, > ^^j^^ .^ ^^^^^ ^^.^^^
20. ** WattereiJ
PiTTlDJE (Pittas).
30. Pitta oreas. Allied to P. cyanoptera of Mnlnya and South China.
Picii)^. (Woodj)ecker»).
31. Picus insularis. Allied to P, iettcofwtus of Jaimn and Siberia.
MEOAL;KMID;f;.
32. Megahnnn Nnrhalis, Allied to AL Oortii of Sumatra and M./aber of Hainan.
No allies in China.
CAPRtMCLOiD.f: (Goatsuckers).
33. Caprimufgtts stictomua, A sub-species of C. ttwnticolus of India and China.
CoLiTMniD.Tc (Pigeons),
34. Treron Formoscf, Allied to Malayan species.
S."). Sphenorercus sororius. Allied to Malayan 8j)ccic8 and to S. Sieboldi of Jnpan.
No allies of these two birds inhabit (^hina.
86, Chafi'ophapn Formotana* Allied to the Indian species which extends to Tenna-
serim and Hainan.
Chap. XVIII.] JAPAN AND FORMOSA. 371
TKTRAONiDiE (Grouse and Partridges).
37. Oreoperdix crudigularis. A peculiar genas of partridges.
38. Bambuticola sonorivox. Allied to the Chinese B. ihoracica.
3!). Areotwmix rostrata. Allied to the Chinese^. Blakistonii,
PuASiAMiDJE (Pheasants).
40. Phasianus Formosanus. Allied to P, torguatns of China.
4 1 . Euplocamus Swinhoei, A very peculiar and beautiful species allied to the tropical
fire-backed pheasants, and to the silver pheasant of North China.
Strigid.c (Owls).
42. Athene pardalota. Closely allied to a Chinese species.
43. Lempigius Hamhroekii, Allied to a Chinese species.
This list exhibits to us the marvellous fact that more than
half the peculiar species of Formosan birds have their nearest
allies in such remote regions as the Himalayas, South India, the
Malay Islands, or Japan, rather than in the adjacent parts of
the Asiatic continent. Fourteen species have Himalayan allies,
and six of these belong to genera which are unknown in China.
One has its nearest ally in the Nilgherries, and five in the Malay
Islands ; and of these six, four belong to genera which are not
Chinese. Two have their only near allies in Japan. Perhaps
more curious still are those cases in which, though the genus is
Chinese, the nearest allied species is to be sought for in some
remote region. Thus, we have the Formosan babbler {Garrvlax
rvficeps) not allied to the species found in South China, but to
one inhabiting North India and East Thibet; while the black
bulbul {IIyp8ipetes nigerrimus) is not allied to the Chinese spe-
cies, but to an Assamese form.
In the same category as the above we must place eight species
not peculiar to Formosa, but which are Indian or Malayan in-
stead of Chinese, so that they ojBfer examples of discontinuous
distribution somewhat analogous to what we found to occur in
Japan. These are enumerated in the following list:
Species of Bihds Common to Formosa and India or Ma lata, but Not
Found in China.
1. Siphia superciUaris, The rufoas- breasted flycatcher of the Soatheast Hima-
iHvas.
2. Halcyon Coromanda, The great red kingfisher of India, Malnjn, and Jnpnn.
8. Palutnbus pulchricolUs, The Darjeeiiog i\-ood- pigeon of the Soatheast Hima-
layas.
372
ISLAND LIFE.
i. TuraU Dus,mm,yi. TliB larger butlon-qunil of IiiJiH.
B. Spiiictat NipaUaiii. Tlie spotted ImiYk-Engle orXejinl and j\Fi«im.
6. LopAoi/iUa Irivirpalit. The crafted eoshawk of ifie Maliiy Islnniis.
7. Bnlaca AViFurtwiV, Tlie brown wood-owl of tlie Hinmlnyas.
B. Slrtji riadidit. Tho groBS-oivI of Jndia and Mnlnvii.
The most interesting of the above are the pigeon and the fly-
catcher, both of which are, bo far as yet known, etrictly conflncd
to the Himalayan mountains and Formosa. They thus afford
examiiles of discontiniions epeeitic distribution exactly parallel
to that of tlie great spotted kingfisher, already referred to as
fonnd only in the Himalayas and Japan.
Comparison of the Faunas of Hainan, Formosa, and Japan,
— Tlie island of Hainan, on the extreme sontli of China, and
only separated from the mainland by a strait fifteen miles wide,
appears to have considerable similarity to Formosa, inasmuch as
it possesses seventeen peculiar land birds (out of 130 obtained
by Mr. Swinlioe), two of wliicli aro close allies of Foruiosan spe-
cies, while two others are identical. We also find four species
wliose nearest allies are in the Himalayas. Our knowledge of
this island and of the adjacent coast of China is not yet sufficient
to enable us to form an accurate judgment of its relations, bnt it
«;ema probable that it was separated from the continent at, np-
pro.\imatoly, the same ei»ch as Formosa and Japan, and that
the special features of each of tJiese islands arc mainly due to
their gcograpliical position. Formosa, being more completely
isolated than citlier of the others, possesses a larger proportion
of peculiar species of birds ; while its tropical situation and lofty
mountain-ranges have enabled it to preserve an nnusual number
of Himalayan and Malayan forms. Japan, almost equally iso-
lated towards tiio south, and having a much greater variety of
climate iis well as n nmch larger area, possesses about an equal
number of nmmniulia with Formosa, and an even larger propor-
tion of peculiar species. Its birds, however, though more nu-
nterouB, are less peculiar; and this is probably duo to the large
number of species' which migrate northward in summer, and
find it easy to enter Japan through the Kunle Isles or Sagha-
licn. Japan, too, is largely peopled by those iiorlhern typos
wliieh have an unusually wide range, and which, being almost
Chap. X VIII.] JAPAN AND FORMOSA. 373
all migratory, are accustomed to cross over seas of moderate ex-
tent. The i*egnlar or occasional influx of these species prevents
the formation of special insular races, such as are almost always
produced when a portion of the population of a species remains
for a considerable time completely isolated. We thus have ex-
plained the curious fact that while the mammalia of the two
islands are almost equally peculiar (those of Japan being most
so in the present state of our knowledge), the birds of Formosa
show a far greater number of peculiar species than those of
Japan.
General Remarks on Recent Continental Islands. — We have
now briefly sketched the zoological peculiarities of an illustrative
series of recent continental islands, commencing with one of the
most recent — Great Britain — in which the process of formation
of peculiar species has only just commenced, and terminating
with Formosa, probably one of the most ancient of the series,
and which accordingly presents us with a very large proportion of
peculiar species, not only in its mammalia, which have no means
of crossing 'the wide strait which separates it from the main-
land, but also in its birds, many of which are quite able to cross
over.
Here, too, we obtain a glimpse of the way in which species
die out and are replaced by others, which quite agrees with what
the theory of evolution assures us must have occurred. On a
continent, the process of extinction will generally take effect on
the circumference of the area of distribution, because it is there
that the species comes into contact with such adverse conditions
or competing forms as prevent it from advancing farther. A
very slight change will evidently turn the scale and cause the
species to contract its range, and this usually goes on till it is
reduced to a very restricted area, and finally becomes extinct.
It may conceivably happen (and almost certainly has sometimes
happened) that the process of restriction of range by adverse
conditions may act in one direction only, and over a limited dis-
trict, so as ultimately to divide the specific area into two sepa-
rated parts, in each of which a portion of the species will con-
tinue to maintain itself. We have seen that there is reason to
believe that this has occurred in a very few cases both in North
374
ISLAND LIFE.
Til.
i and ill Nortticrn Asia (sec pp. 62, Gi). But the same
tiling lins certuiiily occun-ed in a considerable nnmber of cases,
only it lias resulted in tlie divided areas being occupied by rep-
resentaliec forma iustend of by tbc very same species. The
cause of this is very easy to understand. We have already
shown that there is a large amonnt of local variation in a con-
siderable number of species, and we may be sure that were It
not for the const-int intermingling and intercrossing of tlie in-
dividuals inhabiting adjacent localities, this tendency to local
variation would soon form distinct races. But as soon as the
area is divided into two portions, the intei'crossing is stopped,
and the usual result is that two closely allied races, classed as
repn^sentative species, become formed. Such pairs of allied
species on the two sides of a continent, or in two detached areas,
are very numerous; and their existence is only explicable on
the snpposition that tiiey are descendants of a parent form
which once occupied an area comprising that of both of them ;
that this ai-ea then became discontinuous; and, lastly, that, as a
consequence of the discontinuity, the two sections of the parent
species became segregated into distinct races or new species.
Now, when the division of the area leaves one portion of the
species in an island, a similar modification of tiie species, either
in the island or in the continent, occurs, resulting in closely al-
lied but distinct forms; and sucli forms are, as we have seen,
highly characteristic of island faunas. But islands also favor
the occasional preservation of the unchanged species — a phe-
nomenon which very rarely occurs in continents. This is prob-
ably due to the absence of competition in islands, so that the
parent species there maintains itself unchanged, while the conti-
nental portion, by the force of that competition, is driven back
to some remote mountain area, where it too obtains n compara-
tive freedom from competition. Thus may be explained the
cnrious fact that tlie species common to Formosa and India are
generally confined to limited areas in the Himalayas, or in other
cases are found only in remote islands, as Japan or Hainan.
The distribution and atHnities of the animals of continental
islands thus throw much light on that obscure subject— the de-
cay and extinction of s|iccies: while tho numerous and delicate
Chap.XVIU.] japan and FORMOSA. 875
gradations in tho modification of the continental specieg — from
perfect identity, through slight varieties, local forms, and insular
races, to well-defined species and even distinct genera— afford an
overwhelming mass of evidence in favor of the theory of " de-
scent with modification."
We shall now pass on to another class of islands, which,
though originally forming parts of continents, were separated
from them at very remote epochs. This antiquity is clearly
manifested in their existing faunas, which present many peculi-
arities, and offer some most curious problems to the student of
distribution.
376 ISLAND UFE. [Part II.
CHAPTER XIX.
ANCIENT CONTINENTAL ISLANDS: THE MADAGASCAR GROUP.
Remcrks on Ancient Continental Islands. — Physical Features of Madagascar. — Bio-
logical Featares of Madagascar. — Mammalia. — Reptiles. — Relation of Madagascar
to Africa. — Early History of Africa and Madagascar. — Anomalies of Distribution,
and bow to Explain them. — The Birds of Madagascar as Indicating a Supposed
Lemurian Continent. — Submerged Islands between Madagascar and India. — Con-
cluding Remarks on **Lemuria." — The Mascarene Islands. — The Comoro Islands.
— The Seychelles Archipelago. — Birds of the Seychelles. — Reptiles and Amphibia.
— Fresh -water Fishes. — Land Shells. — Mauritius, Bourbon, and Rodriguez. —
Birds. — Extinct Birds and their Probable Origin. — Reptiles. — Flora of Madagas-
car and the Mascarene Islands. — Curious Relations of Mascarene Plants. — En-
demic Genera of Mauritius and Seychelles. — Fragmentary Character of tlic Mas-
carene Flora. — Flora of Madagascar Allied to that of South Africa. — Preponder-
ance of Ferns in the Mascarene Flora. — Concluding Remarks on the Madagascar
Group.
We have now to consider the phenomena presented by a veiy
distinct chiss of islands — those which, although once forming
part of a continent, have been separated from it at a remote
epoch wlien its animal forms were very unlike what they are
now. Such islands preserve to lis the record of a bygone world
— of a period when many of the higher types had not yet come
into existence, and when the distribution of others was very dif-
ferent from what prevails at the present day. The problem
presented by these ancient islands is often complicated by the
changes they themselves have undergone since the period of
their separation. A partial subsidence will have led to the ex-
tinction of some of the types that were originally preserved, and
may leave the ancient fauna in a very fragmentary state; while
subsequent elevations may have brought it so near to the conti-
nent that some immigration even of mammalia may have taken
place. If these elevations and subsidences occurred several times
over, though never to such an extent as again to unite the island
with the continent, it is evident that a very complex result
Chap. XIX.] THE MADAGASCAR GROUP. 377
might be produced ; for, besides the relics of the ancient fauna,
we might have successive immigrations from surrounding lands
reaching down to the era of existing species. Bearing in mind
these possible changes, we shall generally be able to arrive at a
fair conjectural solution of the phenomena of distribution pre-
sented by these ancient islands.
Undoubtedly the most interesting of such islands, and that
which exhibits their chief peculiarities in the greatest perfec-
tion, is Madagascar, and we shall therefore enter somewhat fully
into its biological and physical history.
J^lujsical Features of Madagascar. — This great island is situ-
ated about 250 miles from the east coast of Africa, and extends,
from 12^ to 25^"" S. lat. It is almost exactly 1000 miles long,
with an extreme width of 3G0 and an average width of more
than 260 miles. A lofty granitic plateau, from SO to 100 miles
wide, and from 3000 to 5000 feet high, occupies its central por-
tion, on which rise peaks and domes of basalt and granite to a
height of nearly 9000 feet ; and there are also numerous extinct
volcanic cones and craters. All round the island, but especially
developed on the south and west, are plains of a few hundred
feet elevation, formed of rocks which are shown by their fossils
to be of Jurassic age, or, at all events, to belong to somewhere
near the middle portion of the Secondary period. The higher
granitic plateau consists of bare undulating moors, while the
lower Secondary plains are more or less wooded ; and there is
here also a continuous belt of dense forest, varying from six or
eight to fifty miles wide, encircling the whole island, usually at
about thirty miles' distance from the coast, but in the northeast
coming down to the sea-shore.
The sea around Madagascar, when the shallow bank on which
it stands is passed, is generally deep. This 100-fathom bank is
only from one to three miles wide on the east side, but on the
west it is much broader, and stretches out opposite Mozam-
bique to a distance of about eighty miles. The Mozambique
Channel varies from less than 500 to more than 1500 fathoms
deep, the shallowest part being where the Comoro Islands and
adjacent shoals seem to form stepping-stones to the continent
of Africa. The 500 -fathom line includes Aldabra and the
Chap. XIX.] THE MADAGASCAR GROUP. 379
small Farquliar Islands to the north of Madagascar, while to
the east the sea deepens rapidly to the 1000-fathoin line, and
then more slowly, a profound cliannel of 2400 fathoms separat-
ing Madagascar from Bourbon and Mauritius. To the north-
east of Mauritius are a series of extensive shoals, forming four
large banks less than 100 fathoms below the surface, while the
1000-fathom line includes them all, with an area about half that
of Madagascar itself. A little farther north is the Seychelles
group, also standing on an extensive 1000-fathom bank, while
all around the sea is more than 2000 fathoms deep.
It seems probable, then, that to the northeast of Madagascar
there was once a series of very large islands, separated from it
by not very wide straits; while eastward across the Indian
Ocean we find the Chagos and Maldive coral atolls, marking the
position of other large islands, which together would form a line
of communication by comparatively easy stages of 400 or 500
miles each between Madagascar and India. These submerged
islands, as shown in our map on page 389, are of great impor-
tance in explaining some anomalous features in the zoology of
this great island.
If the rocks of Secondary age which form a belt around the
island are held to indicate that Madagascar was once of less ex-
tent than it is now (though this by no means necessarily fol-
lows), we have also evidence that it has recently been considera-
bly larger ; for along the east coast there is an extensive barrier
coral reef about 350 miles in length, and varying in distance
from the land from a quarter of a mile to three or four miles.
This is good proof of recent subsidence ; while we have no rec-
ord of raised coral rocks inland which would certainly mark
any recent elevation, because fringing coral reefs surround a
considerable portion of the northern, eastern, and southwestern
coasts. We may therefore conclude that during Tertiary times
the island was usually as large as, and often probably much
larger than, it is now.
Biological Features of Madagascar, — Madagascar possesses
an exceedingly rich and beautiful fauna and flora, rivalling in
some groups most tropical countries of equal extent, and, even
when poor in species, of surpassing interest from the singularity,
ISLAND LIFK.
In lliis innp the Jcptli of tho sen is shown liv ilirec lints; i!'e lie'ne't ii"t imii'-sting
fiom 0 10 ion r^iibiinij, ihc medium lint fiom lUu lo lOUO fiiltiutas, ilie cjork tint
more tlinn 1000 rulioms.
Chap. XIX.] THE MADAGASCAR GROUP. 381
the isolation, or the beauty of its forms of life. In order to ex-
liibit the fnll peculiarity of its natural history and the nature
of the problems it offers to the biological student, we must give
an outline of its more important animal forms in systematic
order.
Mammalia. — ^Madagascar possesses no less than sixty-six spe-
cies of mammals — ^a certain proof in itself that the island has
once formed part of a continent ; but the character of these ani-
mals is very extraordinary and very different from the assem-
blage now found in Africa or in any other existing continent.
Africa is now most prominently characterized by its monkeys,
apes, and baboons ; by its lions, leopards, and hyenas ; by its ze-
bras, rhinoceroses, elephants, buffaloes, giraffes, and numerous
species of antelopes. But no one of these animals, nor anything
like them, is found in Madagascar, and thus our first impression
would be that it could never have been united with the African
continent. But as the tigers, the bears, the tapii*s, the deer, and
the numerous squirrels of Asia are equally absent, there seems
no probability of its having been united with that continent.
Let us, then, see to what groups the mammalia of Madagascar
belong, and where we must look for their probable allies.
First and most important are the lemurs, consisting of six
genera and thirty-three species, thus comprising just half the
entire mammalian population of the island. This group of
lowly organized and very ancient creatures still exists scattered
over a wide area ; but they are nowhere so abundant as in the
island of Madagascar. They are found from West Africa to
India, Ceylon, and the Malay Archipelago, consisting of a num-
ber of isolated genera and species, which appear to maintain
their existence by their nocturnal and arboreal habits, and by
haunting dense forests. It can hardly be said that the African
forms of lemui-s are more nearly allied to those of Madagascar
than are the Asiatic, the whole series appearing to be the discon-
nected fragments of a once more compact and extensive group
of animals.
Next, we have about a dozen species of Insectivora, consisting
of one shrew, a group distributed over all the great continents ;
and five genera of a peculiar family, Centetidse, which family
ISLAND LIFE.
il'*«T II.
exists nowhere olee on the globe except in the two largest West
Indian islands, Cuba and Uajti, thns adding etill fiii'tlicr to our
embarraeament in seeking for the original home of the Madar'
gascar fnuna.
We then come to the Carnivorn, whicli are represented by a
peculiar cat-like animal, CrjptoproctH, forming a distinct family,
and having no allies in any part of the globe; and eight civets
belonging to fonr pecnliar genera. Here we lirst meet with some
decided indications of an African origin ; for the civet family
is more abundant in this continent than in Asia, and some of
the Madagascar genera seem to be decidedly allied to African
groups — as, for example, Euplerea to Snricata and Crossarchus.'
Tiie Rodents consist only of four rata and mice of pecnliar
genera, one of which is said to be allied to an American genus ;
and, lastly, we have a river-hog of the African genus Potanio-
chsems, and a small sub-fossil hippopotamns, both of which, be-
ing sotni-aquatic animals, might easily have reached the island
from Africa, by way of the Comoros, witliout any actual land-
connection.
Jieptilea of Jiadaff(Mcar.^PtiBait)g over the birds for the pres-
ent, as not fio clearly demonstrating land-connection, let »a see
what indications are afforded by the reptiles. The large and
universally distributed family of Coltibrine snakes is represent-
ed in Madagascar not by African or Asiatic genera, but by two
American genera — Philodryss and Heterodon, and by Herpeto-
dryas, a genns fonnd in America and China. The other genera
are all pecnliar, and belong mostly to wide-spread tropical fami-
lies ; but two families — L3'codontidiB and Viperida;, botJi abun-
dant in Africa and the Eastern tropics — are absent. Lizai-ds
are mostly represented by peculiar genera of African or tropi-
cal families, bnt several African genera are represented by pe-
culiar species, and there are also some species belonging to two
American genera of the Iguanida?,a family which is exclusively
American j while a genus of geckoes, inhabiting America and
Anslralia, also occurs in Madagascar.
' Sao l)r, .1. E. Griijs "l{evi^ioll ofilie VWetridec," in Pi-ocitdinf'/' itie Zoolog-
ical Soeietj. 18IJ4. p. 007.
Chap. XIX.] THE MADAGASCAR GROUP. 383
Relation of Madagaacar to Africa. — These facts, taken all
together, are certainly very extraordinary, since they show in a
considerable number of cases as much affinity with America as
with Africa ; while the most striking and characteristic groups
of animals now inhabiting Africa are entirely wanting in Mad-
agascar. Let us first deal with this fact, of the absence of so
many of the most dominant African groups. The explanation
of this deficiency is by no means difficult, for the rich deposits
of fossil mammals of Miocene age in France, Germany, Greece,
and Northwest India have demonstrated the fact that all the
great African mammals then inhabited Europe and temperate
Asia. We also know that a little earlier (in Eocene times) trop-
ical Africa was cut off from Europe and Asia by a sea stretch-
ing from the Atlantic to the Bay of Bengal, at which time
Africa must have formed a detached island-continent such as
Australia is now, and probably, like it, very poor in the higher
forms of life. Coupling these two facts, the inference seems
clear that all the higher types of mammalia were developed in
the great Euro-Asiatic continent (which then included Northern
Africa), and that they only migrated into tropical Africa when
the two continents became united by the upheaval of the sea-
bottom, probably in the latter portion of the Miocene or early
in the Pliocene period.*
* This view was, I believet first advanced by Professor Huxley in his "Anniver-
sary Address to the Geological Society" in 1870. He says, **In fact, the Miocene
mammalian fauna of Europe and the Himalayan regions contain, associated togeth-
er, the types which are at pi-esent separately located in the South African and Indian
provinces of Arctogo^a. Now there is every reason to believe, on other grounds, that
both Hindostan south of the Ganges, and Africa south of the Sahara, were separated
by a wide sea from Europe and North Asia during the Middle and Upper Eocene
epochs. Hence it becomes highly probable that the well-known similarities, and no
less remarkable differences, between the present faunae of India and South Africa
have aiiscn in some such fiishion as the following. Some time during the Miocene
epoch, the bottom of the nummulitic sea was upheaved and converted into dry land
in the direction of a line extending from Abyssinia to the mouth of the Ganges. By
this means the Dekkan, on the one hand, and South Africa, on the other, became con-
nected nirh the Miocene drv land and with one another. The Miocene mammals
spread gradually over this intermediate dry land; and if the condition of its eastern
and western ends offei*ed as wide contrasts as the valleys of the Ganges and Arabia
do now, many forms which made their way into Africa must have been different
It is clear, tlierefore, tliat if Madagascar Ijad once formed part
of Africa, but had been separated from it bufure Africa was
united to Europe and Asia, it would not contain any of those
kinds of nnlmals which then first entered the conntry. But,
besides the African mammals, we know that some birds now
contiiied to Africa tRen inhabited Europe, and we may therefore
fnirly ussumo that all the more important groups of birds, I'ep-
ti!c», and insects, now abundant in Africa, but absent from Mad-
agascar, formed no part of the original African fauna, hut en-
tered the country only after it was joined to Europe and Asia,
Eiirh/ Iliatori/ of AfvU'.a, and Maiiag(iscar.—\fe have seen
that Madagascar contains an abundance of iiiamnialB, aud that
most of them are of types either peculiar to, or existing also in,
Africa; it follows that that continent must have had an earlier
union with Europe, Asia, or America, or it could never have ol>-
tnined any ninmuials at all. Kow tlieso ancient African mam-
mals are Leuiui's, Insectivora, aud small Carnivora, chiefly Viver-
ridiB ; and all these groups are knowm to liavo inhabited Europe
ill Eocene and Miocene times; and that the unioa was with
Europe rather than with America is clearly proved by the fact
that even the Insectivorous Ceutctidie, now coutined to Mada-
gascar and the West Indies, inhabited France in tlie Lower
Miocene period; while the ViverridiE, or civets, which form so
important a part of the fauna of Madagascar as well as of Afri-
ca, were abundaut iu Euiupe throughout tlio whole Tertiary
period, but are not known to have ever lived in any part of the
American continent. "Wo here see the application of the prio-
ciple which wo have already fully proved and illustrated (Chap-
ter IV., p. 61), that all extensive groups have a wide range at
the period of their maximum development; but as they decay
fl'oni llio»e wlik'h reoclieil llic nekknn, while others miglit ]Kin inio botli (liew inli-
provinew."
This question is full; discussed in my " Geografihlcnl DiKtrihulJoii of Atkimnls"
(Vol. I., p. 38.'i), wlicre I expreucd views somewhat difi'ei'oiit frum thuso or i'rofensoT
Hiixlev. nnd iimde some alight eiTors wiiiuh nre torrecied in iho presonntnik, A*l
dill not then rorer lo Hrufewnr IloKlev's prior atittement of ihe llieorv ofMiiicene im-
niigrntion into Africa (wliicli I iiiid rand, but the reference lo whicb 1 eould not rs>
call), I am hniipy lu t{iva hii \ien'8 hero.
Chap. XIX.] THE MADAGASCAR GROUP. 385
their area of distribntion diminishes or breaks up into detached
fragments, which one after another disappear till the group be-
comes extinct. Those animal forms which we now find isolated
ill Madagascar and other remote portions of the globe all belong
to ancient groups which are in a decaying or nearly extinct con-
dition, while those which are absent from *t belong to more re-
cent and more highly developed types, which range over exten-
sive and continuous areas, but have had no opportunity of reach-
ing the more ancient continental islands.
Anomalies of DiMrihution^ and how to Explain them. — If these
considerations have any weight, it follows that there is no rea-
son whatever for supposing any former direct connection be-
tween Madagascar and the Greater Antilles merely because the
Insectivorous Centetidse now exist only in these two groups of
islands; for we know that the ancestors of this family must
once have had a much wider range, which almost certainly ex-
tended over the groat northern continents. Wc might as rea-
sonably suppose a land-connection across the Pacific to account
for the camels of Asia having their nearest existing allies in the
llamas and alpacas of the Peioivian Andes, and another between
Sumatra and Brazil, in order that the ancestral tapir of ono
country might have passed over to the other. In both these '
cases we have ample proof of the former wide extension of the
group. Extinct camels of numerous species abounded in North
America in Miocene, Pliocene, and even Post -pliocene times,
and one has also been found in Northwestern India, but none
whatever among all the rich deposits of mammalia in Europe.
We are thus told, as clearly as possible, that from the North
American continent as a centre the camel tribe spread west-
ward, over now-6ubmerged land at the shallow Behring Strait
and Kamtschatka Sea into Asia, and southward along the Andes
into South America. Tapira are even more interesting and in-
structive. Their remotest known ancestors appear in Western
Europe in the early portion of the Eocene period ; in the later
Eocene and the Miocene other forms occur both in Europe and
North America. These seem to have become extinct in North
America, while in Europe they developed largely into many
forms of true tapirs, which at a much later period found their
25
ISLAND UVK.
[PunU.
way again to North and tlieiiee to South America, where their
remains are found in eaves and gravel-deposits. It is nn in-
structive fact that in the Eastern continent, where they were
once 80 abundant, they have dwindled down to a single species.
existing in flinall niimberg in the Malay Penineula, Sumatra, and
Borneo only; while* in the Western continent, where they arc
comparatively recent immigrants, they occupy a much larger
area, and are represented by three or four distinct species. Who
could possibly have imagined such migrations, and extinctions,
and changes of distribution as are demonstrated in the case of
the tapirs if we had only the distribution of the existing species
to found an opinion upon i Such cases as these — and there are
many others equally striking — show ua with the greatest dis-
tinctness how nature has worked in bringing about the exam-
ples of anomalouB distribution that everywhere meet us; and
we must, on every ground of philosophy and common-sense,
apply the same method of interpretation to the more nnnieroua
instances of anomalous distribution we discover among such
gi-oups as reptiles, birds, and insects, where we rarely have any
direct evidence of their past migrations through the discovery
of fossil i-cmains. Whenever we can trace the past liistory of
any group of terrestrial animals, wc invariably iind that its
actual distribution can be explained by migrations effected by
means of comparatively slight modifications of our existing con-
tinents. In no single case have we any direct evidence that the
distribution of land and sea has been radically changed during
the whole lapse of the Tertiary and Secondary periods, while,
as we have already shown iu onr tifth chapter, the testimony
of geology itself, if fairly interpreted, upholds the same theory
of the stability of our continents and the permanence of our
oceans. Yet so easy and pleasant is it to specnlafe on former
changes of land and sea with which to cut the Gordian knot
offered by anomalies of distribution that M'e still continually
meet with suggestions of former continents stretching in every
direction across the deepest oceans, in oi-der to explain the pres-
ence in remote parts of the globe of the same genera even of
plants or of insects — organisms which possess such exceptional
facilities both for terrestrial, aerial, and oceanic transport, and of
Chap. XIX.] THE MADAGASCAR GKOUP. 387
whose distribution in past ages we generally know absolutely
nothing.
The Birds of Madagascar as Indicating a Supposed Leinu-
rian Cmitinent — Having thus shown how the distribution of
the land mammalia and reptiles of Madagascar may be well ex-
plained by the supposition of a union with Africa before the
greater part of its existing fauna had reached it, we have now
to consider whether, as some ornithologists think, the distribu-
tion and affinities of the birds present an insuperable objection
to this view, and require the adoption of a hypothetical conti-
nent— Lemuria — extending from Madagascar to Ceylon and the
Malay Islands.
There are about one hundred land birds known from the isl-
and of Madagascar, all but four or five being peculiar ; and
about half of these peculiar species belong to peculiar genera,
many of which are extremely isolated, so that it is often diffi-
cult to class tliera in any of the recognized families, or to de-
termine their affinities to any living birds. Among the other
moiety, belonging to known genera, we find fifteen which have
undoubted African affinities, while five or six are as decidedly
Oriental, the genera or nearest allied species being found in In-
dia or the Malay Islands. It is on the presence of these pecul-
iar Indian types that Dr. Hartlaub, in his recent work on the
" Birds of Madagascar and the Adjacent Islands," lays great
stress, as proving the former existence of "Lemuria;" while
he considers the absence of such peculiar African families as
the plantain-eaters, glossy-starlings, ox-peckers, barbets, honey-
guides, hombills, and bustards, besides a host of peculiar Af-
rican genera, as sufficiently disproving the statement in my "Ge-
ographical Distribution of Animals" that Madagascar is "more
nearly related to the Ethiopian than to any other region," and
that its fauna was evidently " mainly derived from Africa."
But the absence of the numerous peculiar groups of African
birds is so exactly parallel to the same phenomenon among mam-
mals that we are justified in imputing it to the same cause, the
more especially as some of the very groups that are wanting —
the plantain-eatera and the trogons, for example — are actually
known to have inhabited Europe along with the large mamma-
ISLAND LIFE.
[Piar II.
lia w]iicli subsequently migrated to Africa. As to tlm peculiarly
Eastern genera — siicli as Copsycbus and llypsipetes, witli a Di-
cnirue, Ploccus, a Oisticoln, and a ^^cops, all closely allied to In-
dian or Malayan species — althougli very strikiug to tlio orni-
thologist, tlioy certainly do not outweigh the fourteen African
genera found in ifadagascar. Their presence may, moreover,
bo accounted for more satisfactorily tlian by means of an an-
cient Leinurian continent, wliicli, even if granted, would not ex-
plain the very facts adduced in its support.
Let ua firet prove this latter statement.
The supposed "Lemuria" ninst have existed, if at all, at so
remote a period that the higher animals did nut then inhabit
either Africa or Southern Asia, and it must have become par-
tially or wholly submerged before tbey reached those countries;
otherwise wo should find in Madagascar many other iiiiimala
besides I-emure, Insectivora, and Viverridie, especially sneU ac-
tive arboreal creatures as monkeys and squirrels, such hardy
grazers as doer or antelopes, or such wide-ranging carnivores as
foxes or bears. This obliges us to date the disappearance of
the hypothetical continent about the earlier part of the Miocene
epoch nt latest, for during the latter part of that period we
know that such animals existed in abundance in every part of
the great northern continents wherever we have found organic
remains. But the Oriental birds in Madagascar, by whose pres-
ence Dr. ITartlanb upholds the theory of a Lenmria, are slightly
modified forms of existing Indian genera, or Bometimes, as Dr.
Ilartlaub himself points out, species hardlij distinguishabli'. from
thone of India. Now all tlie evidence at our command leads
u8 to conclude that, even if these genera and species wore in
existence in the early Miocene period, tJiey must have had a
widely different distribution from what they have now. Ahmg
with so many African and Indian genem of mammals, they then
probably inhabited Europe, which at that epoch enjoyed a sub-
tropical climate; and this is rendered almost certain by the dis-
covery in the Miocene of France of fossil remains of trogona
and jungle-fowl. If, then, these Indian birds date back to the
very period during which alone Lemuria could have existed,
that continent was quite unnecessary for their introiluction into
i^U.
CHir. XIX.}
THE MADAGASCAlt GllOtJI'.
Madagascar, as tliey conM have followed tlie same track as the
mammalia of Miocene Europe and Asia; while if, as I main-
tain, they ni-e of more recent date, then I^mnria liad ceased to
esist, and conld not have been tlie means of their introduction.
Submerged Idwnds iciween Madoffoscar and India. — Look-
ing at the Accompanying map of the Indian Ocean, we gee that
between Madagascar and India there are now extensive shoals
and coral reefs, such as are always lield to indicate subsidence ;
iiiid we may therefore fairly j»ostnlate the former existence hei'c
of several large islands, some of them not much inferior to
Madagascar itself. These reefs arc all separated from each other
by very deep sea — mnch deeper than that wliicli divides Mada-
gascar from Africa, and wo have tlierefore no reason to imagine
their former nnion. Bnt they wunld. neverthulese, greatly facili-
tate tlie introdnctton of Indian birds into the Maecarenc Islands
and Madagascar ; and these facilities existing, such an iminigra-
ISLAND LIFE.
tO.
tioii woiiKI be sure to tiike place, just as surely as American
birds iiave entered tlie Galapagos and Junn Fernandez, a& Euro-
pean Iiiitis now reach tlie Azores, and as Australian birds reach
Biieh a distant island as New Zealand, This wonid take place
the more certainly because the Indian Ocean is a region of vio-
lent periodical storms at the changes of the monsoons, and we
have seen in the case of the Azores and Bermnda Low impor-
tant a fai:tor this is in determining the transport of birds across
the ocean.
Mr. Darwin's theory of tho fornjation of atolls is now almost
universally accepted as the true one, and this theory implies
that the arciis in question are still, or have very recently been,
subsiding. The final disappearance of these now sunken islands
does not, therefore, iu all pi'obability, date back to a very remote
epoch; and this exactly at-cords with the fact that some of the
birds, as well as the frnit-bats of tho genus Pteropus, are very
closely allied to Indian species, if not actually identical, others
being distinct species of the same genera. The fact that not
one closely allied species or even genua of Indian or Malayan
mammals is found in Madagascar eufBciently ])roves that it is
no land-connection that has brought about this sjnall infusion of
Indian birds and bats; while we have sufficiently shown that,
when we go back to remote geological times, no land-connection
in this direction was necessary to explain the phenomena of the
distribution of the Lemurs and Inseetivora. A land-connection
with some continent was undoubtedly neeessnry, or there would
have been no mammalia at all in Madagascar; and the nature
of its fauna, on the whole, no less than the moderate depth of
the intervening strait and the eomparativD approximation of the
opposite shores, clearly indicate that the connection was with
Africa,
CondutViiiij Itemarlf^ on " Lemnria." — I have gone into this
question in some detail, because Dr. Hartlaul/e criticism on my
views has been reproduced in a seientific periodical,' and the
supposed licmurian continent is constantly referred to by <]uasi-
scientitic writers, as well as by natnnilists and geologists, as if its
Chap. XIX.] THE MADAGASCAR GROUP. 391
existence had been demonstrated by facts, or as if it were abso-
lutely necessary to postulate such a land in order to account for
the entire series of phenomena connected with the Madagascar
fauna, and especially with the distribution of the Lemuridae/
I think I have now shown, on the other hand, that it was essen-
tially a provisional hypothesis, very useful in calling attention
to a remarkable series of problems in geographical distribution,
but not affording the true solution of those problems, any more
than the hypothesis of an Atlantis solved the problems present-
ed by the Atlantic Islands and the relations of the European
and North American flora and fauna. The Atlantis is now rare-
ly introduced seriously except by the absolutely uuscientitic, hav-
ing received its death-blow by the chapter on Oceanic Islands in
the " Origin of Species," and the researches of Professor Asa
Gray on the affinities of the North American and Asiatic floi^as.
But " Lemuria" still keeps its place — a good example of the sur-
vival of a provisional hypothesis which offers what seems an
easy solution of a diflieult problem, and has received an appro-
priate and easily remembered name, long after it has been proved
to be untenable.
It is now more than four yeare since I first showed, by a care-
ful examination of all the facts to be accounted for, that the
» In a paper read before the Geological Society in 1874, Mr. II. F. Blanford,
from the Himihirity of the fossil plants and reptiles, supposed that India and South
Africa had been connected by a continent, **and remained so connected with some
short intervals from the Permian up to the end of the Miocene period,'* and Mr.
Woodward expressed his satisfaction with ''this further evidence derived from the
fossil flora of tlie Mesozoic series of India in con'oboration of the former existence
of an old submerged continent — Lemuria."
Those who have read the preceding chapters of the present work will not need to
have pointed out to them how utterly inconclusive is the fragmentary evidence de-
rived from such remote periods (even if there were no evidence on the other side) as
indicating geographical changes. The notion that a similarity in the productions of
widely separated continents at any past epoch is only to be explained by the exist-
ence of a direct land-connection, is entirely opposed to all that we know of the wide
and varying distribution of all types at different periods, as well as to the great pow>
crs of dispersal over moderate widths of ocean possessed by all animals except mam-
malia. It is no less opposed to what is now known of the general permanency of the
l^reat continental and oceanic areas ; while in this particular case it is totally incon-
^istent (as has been shown above) with the actual facts of the distribution of animals.
399
ISLAND LIFE.
[PiBT n.
Iiypotliesis of a Lenniriaii continent was .ilike unnecessary to ex-
plain one portion of the facts, and inadequate to explain the re-
inuining portion.' Since that time I have seen no attempt even
to discuss the question on general grounds in opposition to my
views, nor, on the other liand, have those who have hitherto
supported the hypothesis taken nny opportunity of acknowledg-
ing its weakness and inutility. I iiave therefore here explained
uiy i-easons for rejecting it somewhat more fully and in a more
popular form, in the hope thjit a cheek may thus be placed on
the continued restatement of this unsound tlieory us if it were
one of tlie accepted conclusions of modern Bcience.
The Jfascarene /glands'— In the " Geographical Distribntion
of Animals," a summary is given of all that was known of the
zoology of the various islands near Madagascar, which to some
extent partake of its peculiarities, and with it form tlie Malagasy
sub-region of tiie Ethiopian region. As no great additions havo
since been made to our knowledge of the fauna of these inlands,
and my object in this voiume being more especially to illustrate
the mode of solving distrihutional problems by means of the
most suitable examples, 1 shall now confine myself to pointing
nut how far the fads presented by these outlying islands sup-
port the views already enunciated with regard to the origin of
the Madagascar ftuina.
The Comoro Islaiuls. — This group of islands is situated nearly
midway between the northern extremity of Madagascar and tlie
coast of Africa. The four chief islands vary between sixteen
and forty miles in length, the largest being ISO miles from llie
const of Africa, while one or two smaller islets are less than
100 miles from Madagascar. All are volcanic, Great Comoro
being an active volcano 8500 feet high ; and, as already stated,
they are situated on a submarine bank with less than .'lOO fath-
oms soundings, oouuecting Madagascar with Africa. There is
reason to believe, however, that these islands are of compara-
tively i-ecent origin, and that the bank has been formed by mat-
' " Oeogrnpliicnl DiMribnlion of Animnis," Vol. L.p- S72-29S.
' The term " Mnscai'ene " ii used here in an e.'clenileil icnie lo incliiile nil ilie isl-
mill* ncai' Mndngnscnr nliidi resemble it in tlieir nniinnl .ind vogctabla jiroiliii-iioiii.
Chap. XIX.] THE MADAGASCAR GROUP. 393
ter ejected by the volcanoes or by upheaval. Anyhow, there is
no indication whatever of there having been here a land-con-
nection between Madagascar and Africa, while the islands them-
selves have been mainly colonized from Madagascar, to the 100-
fathom bank surrounding which some of them make a near ap-
proach.
The Comoros contain two land mammals, a lemur and a civet,
both of Madagascar genera and the latter an identical species,
and there is also a peculiar species of fruit-bat {Pteropus Como-
renms\ a group which ranges from Australia to Asia and Mada-
gascar, but is unknown in Africa. Of land birds forty-one spe-
cies are known, of which sixteen are peculiar to the islands,
twenty-one are found also in Madagascar, and three found in
Africa and not in Madagascar ; while of tlu3 peculiar species six
belong to Madagascar or Mascarene genera.
These facts point to the conclusion that the Comoro Islands
have been formerly more nearly connected with Madagascar
than they are now, probably by means of intervening islets and
the former extension of the latter island to the westward, as in-
dicated by the extensive shallow bank at its northern extrcm- -
ity, so as to allow of the easy passage of birds, and the occasion-
al transmission of small mammalia by means of floating trees.*
The ISei/chellea Archipelago. — This interesting group consists
of about thirty small islands situated 700 miles N.N.E. of Mada-
gascar, or almost exactly in the line formed by continuing the
centi-al ridge of that great island. The Seychelles stand upon a
rather extensive shallow bank, the 100-fathom line around them
enclosing an area nearly 200 miles long by 100 miles wide, while
the 500-fathom line shows an extension of nearly 100 miles in a
southern direction. All the larger islands are of granite, with
mountains rising to 3000 feet in Mahe, and to from 1000 to
2000 feet in several of the other islands. We can therefore
hardly doubt that they form a portion of the great line of up-
heaval which produced the central granitic mass of Madagascar,
intervening points being indicated by the Amirantes, the Provi-
* For the birds of the Comoro I.^lnnd?, see Proceedings of the Zoological Society^
1877, p. 295, and 1879, p. G73.
ISLAND LIFIi:.
[I'ARi ir.
dence, ami the Fai-quliar lelands, wliicli. iboitgh all cornUine,
probably rest on a gi'anitic ba&is. Deep cbannek of mure tlian
1000 fathoms now aeiiarate tlicse lelnnds from each otlicr, and i£
they were ever aufficicntly elevated to be united, it was probably
at ft very remote epoeb.
Tile Seyehelles may tluia have had ample facilities for receiv-
ing from Madagascar such immigrants as can pass over narrow
eeae; and, on the other hand, tliey were eqmilly favorably elta-
iited as rcgai-ds the exteneive !^aya do Mnllta and Cargados banks,
which were probably once large islands, and may iiave supported
a rich insular flora and fauna of mixed Mascarene and Indian
type. The existing fnniia and flora of the Seychelles must there-
fore be looked npon an the remnants wliich have Bnrvived the
partial submergence of a very exteneive island ; and the entire
absence of mammalia may be due either to this island having
never been actually united to Madagascar, or to its having since
undergone so much submergence as to have led to the extinc-
tion of such mammals as may once have inhabited it. The birds
and reptiles, liowever, thoufrh few in number, are very interest-
ing, and tlirow some further light on the past history of the
Seychelles.
Blrd^ of f/te Seyelu.-U<'8. — Fifteen indigenous land birds are
known to inhabit the gronp, thirteen of wliich are peculiar spe-
cies,' belonging to genera which occur also in Madagascar or
Africa. The genera which are more peculiarly Indian are, Cop-
sychus and Idypsipetes, also found in Madagascar; and PalBe-
ornis, which has species in Hanritius and Kodrigiiez, as well
as one on the continpnt of Africa. A black parrot (Goracopsia),
congeneric with two species that inhabit Madagascar and with
■ '['he fulloiving U a lis! at tlicsc peculini
and IHIII, JbD;]:
KUiiin Seycliollenaii.
Coptj'chu* Sovcliellanim.
llfiwipctBi criiisinMiTit.
Tcliitre* i'orvina.
N«ctnriiita Ilunuirieri.
ZotMrop* moileiin.
FoiiJiii Nojclicllnriiin.
Iiii'dii (>«e Itie Hit fur tRI!7, p. 8u9i
CuLVituA
Alectornnini pulclierriinut.
'I'unur RHtniiiu.
Tiimanciiliiii p^cilifc
CuAP. XIX.] THE MADAGASCAR GROUP. 395
one tliat is peculiar to the Comoros ; and a beautiful red-headed
blue pigeon {Alectorcencut pidcfierrimxi^) allied to those of Mad-
agascar and Mauritius, but very distinct, are the most remarka-
ble species characteristic of this group of islands.
Reptiles and Amphibia of the Seychelles. — The reptiles and
amphibia are rather numerous and very interesting, indicating
clearly that the islands can hardly be classed as oceanic. There
are five species of lizards, three being peculiar to the islands,
while the two others have a rather wide range. The first is a
chameleon — a defenceless slow-moving lizard, especially abundant
in Madagascar, from which no less than twenty-one species are
now known, about the same number as on the continent of Af-
rica. Tiie Seychelles species {Chanieleo tigris) is peculiar to the
islands. The next is one of the skinks {Eaprepes cyanoga8ter\
small ground-lizards with a very wide distribution in the Eastern
Hemisphere. This species is, however, peculiar to the islands.
The other peculiar species is one of the geckoes {Phelsuma Set/-
chellefisis). An East African species (P. cepedianus) is also found
in the Seychelles, as well as in the Comoro Islands, Bourbon,
Mauritius, Madagascar, and Ilodriguez ; and there is also a third
gecko of another genus {Peropus mutilatm) which is found also
in Mauritius, Bourbon, Rodriguez, and Ceylon, and even in
Penang and the Philippine Islands. These lizards, clinging as
they do to trees and timber, are exceedingly liable to be carried
in ships from one country to another, and I am told by Dr.
GUnther that some are found almost every year in the London
Docks. It is therefore probable that when species of this fam-
ily have a very wide range they have been assisted in their mi-
grations by man, though their habit of clinging to trees also rcn-
tlere them likely to be floated with large pieces of timber to con-
siderable distances. Dr. Percival Wright, to whom I am in-
debted for much information on the productions of the Sey-
chelle Archipelago, informs me that the last-named species
varies greatly in color in the different islands, so that he could
always tell from which particular island a specimen had been
brought. This is analogous to the curious fact of certain lizards
on the small islands in the Mediterranean being always very
different in color from those of tlic mainland, usually becoming
BLAND LIFE.
CPaiit ir.
rleli blue or black (see Nature, Vol. XIX., p. 97); and we thus
learn bow readily in some cases differencea of color are brought
about by local conditions.
Snakes, aa is usually tbe case in 8rii,ill or remote islands, are
far less niimorous than lizards, only two species being known.
One, Dromieus Sirychellensis, is » peculiar species of the family
Colubridte, the rest of tbe genus being found in Madagascar and
South America. The other, Boodon. geometricus, one of the
Lycodontidie, or fanged ground-snakes, inhabits also South and
West Africa. So far, then, as the reptiles are concerned, there
is nothing bnt what is easily explicable by what we know of the
general means of distribution of these animals.
We now come to the amphibia, which are represented iu the
Seychelles by two tailless and two serpent -like forms, Tho
frogs are, I^ana Maacar'tenmH, found also in Mauritius, Bourbon,
Angol.% and Abyssinia, and probably all over tropical Africa ;
and Megali^aliia infrarufiis, a tree-frog altogether peculiar to
the islands, and forming a peculiar genus of the wide-spread
tropical family Polypedatidte. It is found. Dr. Wright informs
inc, on the Pundani, or screw-pines; and as these form a ve\y
characteristic portion of tlie vegetation of the Mascavene Islands,
all the species being peculiar and coufined each tu a single isl-
and or small group, we may perhaps consider it as a relic of the
indigenous fauna of that more extensive land of which tlie pres-
ent islands are the remains.
Tho serpentine amphibia are represented by two epeciea of
Cfficilin. These creatures externally resemble large worms, ex-
cept that they have a true head with jaws and rudimentary
eyes, while intoraally they have, of coui-sc, a true vertebrate skel-
eton. They live underground, burrewing by means of the ring-
like folds of the skin, whicli simulatQ the jointed aegnients of a
■worm's body ; and when caught they exude a viscid slime. The
young have external gills which are afterwai-ds replaced by triio
lungs, and this peculiar metamorphosis shows that thcr belong;
to tho amphibia rather than to the reptiles, Tije Camellias are
widely but very sparingly distributed through all the tropical
regions — a fact which may, as we have seen, bo taken as an in-
dication of the great antiipiity of the group, and that it is now
Chap. XIX.] THE MADAGASCAR GUOUP. 397
verging towards extinction. In the Seychelle Islands two spe-
cies have been found, named respectively Ccecilia oxyura and
C. ro8traia. The former also inhabits the Malabar coast of
India, while the latter has been found in West Africa and also
South America.* Tliis is certainly one of the most remarkable
cases of the wide and discontinuous distribution of a species ^
known ; and when we consider the habits of life of these ani-
mals, and the extreme slowness with which it is likely they can
migrate into new areas, we can hardly arrive at any other con-
clusion than that this species once had an almost world-wide
range, and that in the process of dying out it has been left
stranded, as it were, in these three remote portions of the globe.
The extreme stability and long persistence of specific form
which this implies is exti*aordinary, but not unprecedented,
among the lower vertebrates. The crocodiles of the Eocene
period diflfer but slightly from those of the present day, while a
small fresh-water turtle from the Miocene deposits of the Siwalik
Hills is absolutely identical with a still living Indian species,
Emya tectus. The mud-lish of Australia, Ceratodus Forsterij is
a very ancient type, and may well have remained specifically
unchanged since early Tertiary times. It is not, therefore, in-
credible that the Seychelles C(6cilia may be the oldest land
vertebrate now living on the globe — dating back to the early
part of the Tertiary period, when the warm climate of the
Northern Hemisphere in high latitudes, and the union of the
Asiatic and American continents, allowed of the migration of
such types over the whole Northern Hemisphere, from which
they subsequently passed into the Southern Hemisphere, main-
taining themselves only in certain limited areas where the phys-
ical conditions were especially favorable, or where they Were
saved from the attacks of enemies or the competition of higher
forms.
Frtsh-waUr Ftsfves, — The only other vertebrates in the Sey-
* Specimens nre recorded from West Africa in the Proceedingn of the Academy of
Natural Science^ Pliilndelpliin, 1857, p. 72, while specimens in the I'nris Museum
were brought by D'Orbigny from South America. Dr. Wright's s|)ecimcns from the
Seychelles hnve, ns he informs me, been determined to be the same species by Dr.
Peters, of Berlin.
I&IiAHD IrlFS.
[paei ir.
chellee ai-e two fresh-water fishes abounding in the streams and
rivHleta, One, IliiplochUus Playfairli, is peculiar to the islands,
but tliei-o are allied species in Madagascar. It is a pretty little
Jieh about four inches long, of an olive color, with rows of red
spots, and is very abundant in some of the mountain streams.
The iishes of this genus, as I am iuformed by Dr. Giinther, often
inhabit both aea and freph water, so tliat their migration from
Madagascar to the Seychelles and subsequent modilication offer
no diliiculty. The other species is Fundulua orthonotus, found
also on the east coast of Africa ; and as both belong to the same
family — Cyprinodontidie — this may possibly have migrated in a
similar manner.
IaxwI Sftdla. — The only other group of animals inhabiting the
Seychelles which we know with any approach to completeness
are the iand and fresli-water mollusca, but they do not furnish
any facts of special interest. About forty species are known ; and
Mr, Geoffrey Nevill, who has studied them, thinks their meagre
number is chiefly owing to the destniction of so much of the
forests which once covered the islands. Seven of the species —
and among them one of the luost conspicuous, Achalina fulica
— have almost certainly been introdneed; and the remainder
show a mixture of Madagascar and Indian forms, with a prepon-
derance of the latter. Five genera — Streptaxis, Cyiithoponea,
Onchidiuni, Helicina, and I'aludonius — arc mentioned as being
especially Indian, while only two — Tropidophora and Gibbus —
are found in Madagasc-ar, but not in India.' About two thirds
of the species appear to be peculiar to the islands.
Mauritius, jSoufbim, and Rodrigties. — These three islands are
somewhat out of place in this chapter because they really belong
to the oceanic group, being of volcanic formation, surrounded by
deep sea, and possessing no indigenous mammals or amphibia.
Tet their productions are so closely related to those of lladngas-
car, to which they may be considered as attendant satclliteti, that
it is absolutely necessary to associate them together if wc wish
to comprehend and explain their many interesting features.
' " A'litiiiunnI Noten on ilie f^inrl Slivlli of Hie SFydiKlle UlnmlH," by Geoffi^
Koiill. C.M.Z.S.. ill Proetediagi Bflhe Zuolnffiral Sorifty, I8C», [i. 01.
Chap. XIX.] THE MADAGASCAR GROUP. 399
Mauritius and Bourbon arc lofty volcanic islands, evidently of
great antiquity. They are about 100 miles apart, and the sea be-
tween them is less than 1000 fathoms deep, while on each side
it sinks rapidly to depths of 2400 and 2600 fathoms. We have
therefore no reason to believe that they have ever been connect-
ed ^vith Madagascar, and this view is strongly supported by the
character of their indigenous fauna. Of this, however, we have
not a very complete or accurate knowledge, for though both isl-
ands have long been occupied by Europeans, the study of their
natural products was for a long time greatly neglected, and, ow-
ing to the rapid spread of sugar cultivation, tlie virgin forests,
and with them, no doubt, many native animals, have been almost
wholly destroyed. There is, however, no good evidence of there
ever having been any indigenous mammals or amphibia, though
both are now found and are often recorded among the native
animals.*
The smaller and more remote Eodriguez is also volcanic ; but
it has, besides, a good deal of coralline rock — an indication of par-
tial submergence, and helping to account for the poverty of its
fauna and flora. It stands on a 100-fathom bank of considerable
extent, but beyond this the sea rapidly deepens to more than
' In Maillnrd's ** Notes sur Tile de Reunion/' n considerable number of ranrnmnlia
are given ns ** wild/' such as Lemur mongoz and Centetes selosus, botli Mndn^isvar
species, with such undoubtedly introduced animnls as a wild-cat, a linrc, and several
mts and mice. He also gives two species of frogs, seven lizards, and two snakes.
The latter are both Indian species and certainly imported, as are most probably the
frogs. Legouat, who resided some years in the island nearly two centuries ago, and
who was a close observer of nature, mentions numerous birds, large bats, land tor-
toises, and lizards, but no other reptiles or venomous animals except scorpions. We
may be pretty sure, therefore, that the land mammalia, snakes, and frogs now found
wild have all been introduced. Of lizards, on the other hand, there are several spe-
cies, some peculiar to the island, others common to Africa and the other Mascarene
Islands. Tiie following list by Professor Dumeril is given in Maillard*s work:
riaty dactyl us cepedianns. Ilemidactylns frenatus.
*' ocellatus. Gongylus Bojerii.
Ilemidactylns Peronii. Ablepharus Peronit
** ' mutilatns.
Four species of chameleon are now recorded from Bourbon and one from Mauri-
tius (J. Reay Greene, M.D., in Popuiar Science Review^ April, 1880) ; but as they are
not mentioned by the old writers, it is pretty certain that these creatures are recent
introductions, and this is the more probable as they are favorite domestic pets.
400
ISLAND LIFE.
2000 fatlioms; so tliat it is truly oceanic, like its larger sister-
isles.
Birds. — Tlie liviug birds of these islands arc few in nitinbsr,
Aud cousigt mainly uf peculiar species of Mascureiic types, to-
gether witli two peculiar genera — Oxynotus belonging to the
Cnuipephngidte or caterpillar-catchers, a family abnnduut in the
Old World tropics; aud a dove, Trocazza, forming a peculiar
sub-geniie. The origin of these birds ofEers no difficulty, look-
ing at the position of the islands and of the eurrounding shoals
and islets.
Jictinct Birtls. — These three islands are, however, pre-eini-
nently remarkable as being tlie home of a group of large ground-
birds, quite incapable of Hight, and altogether nnlike anything
found elsewbero on the globe; and which, tJiough once very
abundant, have become totally extinct within the last two hun-
dred years. The best-known of these birds is the dodo, which
inhabited Manritins; while allied species certainly lived in
Bourbon and Kodrigiiez, abundant remains of the species of
the latter island — the "solitaire" — -having been discovered, cor-
responding with tho figure and description given of it by Le-
guat, who i-esidcd in Rodriguez in ltil>2. These birds constitute
a distinct family, Dididfe, allied to the pigeons, but very isolat-
ed. They were quite helpless, and were rapidly exterminated
when man introduced dogs, pigs, and cats into tlie islands, and
himself sought them for food. The fact that such perfectly de-
fenceless ereutiu'es survived in great abundance to a quite recent
period in these three islands only, while there is no evidence of
their ever having inhabited any other countries whatever, is it-
self almost demonstrative that Mauritins, Bourbon, and Eodri-
giiez are very ancient but truly oceanic islands. Fmm what we
know of the general similarity of Miocene bii-ds to living genera
aud f.iniilies, it seems clear that the origin of so remarkable a
type as the dodos must date back to early Tertiary times. If we
suppose some ancestral ground- feeding pigeon of large size to
have reached the group by means of intervening islands after-
wards submerged, and to have thenceforth remained to increase
and multiply, unchecked by the attacks of any more powerful
animals, we can well understand that the wings, being useless,
Chap. XIX.] THE MADAGASCAR GKOUP. 401
would in time become almost aborted.* It is also not improbable
tliat this process would be aided by natural selection, because
the use of wings might be absolutely prejudicial to the birds in
their new home. Those that flew up into trees to roost, or tried
to cross over the moutlis of rivers, might be blown out to sea
and destroyed, especially during the hurricanes which have
probably always more or less devastated the islands ; while, on
the other hand, the more bulky and short-winged individuals,
who took to sleeping on the ground in the forest, would be pre-
served from such dangers, and perhaps also from the attacks of
birds of prey which may always have visited the islands. But
whether or not this was the mode by w^hich these singular birds
acquired their actual form and structure, it is perfectly certain
that their existence and development depended on complete iso-
lation and on freedom from the attacks of enemies. We have
no single example of such defenceless birds having ever existed
on a continent at any geological period, whereas analogous though
totally distinct forms do exist in New 2^aland, where enemies
are equally wanting. On the other hand, every continent has
always produced abundance of carnivora adapted to prey upon
the herbivorous animals inhabiting it at the same period ; and
we may therefore be sure that these islands have never formed
part of a continent during any portion of the time when the
dodos inhabited them.
* That the dodo is really nn iibortioii from a more perfect ty|>o, and not n direct
development from some lower form of wingless bird, is shown by its possessing a
keeled sternum, though the keel is exceedingly reduced, being only three quarters
of an inch dee]) in a length of seven inches. The most terrestrial pigeon — the Didnn-
culus of the Sarooan Islands — has a far deeper and better-developed keel, showing
that in the case of the dodo the degradation has been extreme. We have also anal-
ogous examples in other extinct birds of the same group of islands, such as the flight-
less rails, Aphanapteryx of Mauiitius and Erythromachus of Kodriguez, as well as
the large parrot, Lopljopsittacas of Mauritius, and the night heron, Nycticorax me-
(jnrtphala of Kodriguez, the last two birds probably having been able to fly a little.
'J1ie commencement of the same process is to be seen in the peculiar dove of the Soy-
cliclles, Turtur rostratus, which, as Mr. Edward Newton has shown, has much short-
er wings than its close ally, T. picUtratus^ of ^fadagascar. For a full and interesting
account of these and other extinct birds, see Professor Newton's article on ** Fossil
Birds," in the Enr.ycloptvdia Britnnnica, 9th ed., Vol. III., p. 732, and that on
** The Extinct Birds of liodriguez,*' by Dr. A. Giinther and Mr. E. Newton, in the
Royal Societv's volume on the *• Transit of Venus Expedition."
2G
409
ISLAND LIFE.
[Paht ir.
It is a remarkable thing that an ornithologist of Dr. Uart-
laiib's reputation, looking at the subjoct from a purely ornitLo-
logical point of view, should yet entirely ignore the evidence of
these wonderful and unique bii-ds against hia own theory, when
he 6o coniidently characterizes Lcmuria as "that sunken land
which, containing parts of Africa, must have extended far east-
ward over Southern India and Ceylon, and the highest points of
which we recognize in the volcanic peaks of Bourbon and Mau-
ritius, and in the eentral range of Madagascar itself — -the last re-
sorts of the mostly extinct Lemurine race which formerly peo-
pled it." ' It is here implied that lemurs formerly inhabited
Bourbon and Mauritius, but of this there is not a particle of ev-
idence ; and we feel pretty sure that had they done eo, the dodos
would never have been developed there. In Madagascar there
are no traces of dodos, while there are remains of extinct gigan-
tic strnthious birds of the genus ^Epyornis, which were, no
doubt, as well able to protect tiieiusclves against the smaller car-
nivora as are the ostriches, cnms, and cassowaries in their re-
spective countries at the present day.
The whole of tlie evidence at onr command, therefore, tends
toestablisli in avery complete manner the "oceanic "character of
the three islands — ^Mauritius, Bourbon, and Bodriguez, and that
they have never formed part of " Lemuria," or of any continent.
JieptU'ea, — Mauritius, like Bourbon, has lizards, some of which
are peculiar species; but no snakes, and no frogs or toads but
such as have been introduced.* Strange to say, however, a email
islet called Itound Island, only about a mile across, and situated
about fourteen mih's northeast of Mauritius, possesses a snake
which is not only unknown in Munritins, bnt also in any other
part of the world, being altogether contiued to this minute islet 1
It belongs to the Python fiintily, and forms a peculiar and very
distinct genus, Casarca, whose nearest allies seem to be the Un-
galia of Cuba and Bolgeria of Australia. It is hardly possible to
believe that this ser|)ent has very long maintained itself on so
!0 IbU, 1877. p. flM4.
iiifurmcd by Dr. UUnl
CuAP. XIX.] TUE MADAGASCAU GROUP. 403
small an island ; and thongh we have no record of its existence
on Mauritius, it may very well have inhabited the lowland for-
ests without being met with by the early settlers ; and the intro-
duction of swine, which soon ran wild and effected the final de-
struction of the dodo, may also have been fatal to this snake. It
is, however, now almost certainly confined to the one small islet,
and is probably the land vertebrate of most restricted distribu-
tion on the globe.
<.)n the same island there is a small lizard, Thyinis Boyeri^ also
a peculiar species and genus, but this is recorded from Mauritius
and Bourbon as well, though it appears to be rare in both islands.
As Round Island is connected with Mauritius by a bank under
a hundred fathoms below the surface, it has probably been once
joined to it, and when first separated would have been both
much larger and much nearer the main island — circumstances
which would greatly facilitate the transmission of these reptiles
to their present dwelling-place.
Flora of Madagascar and the Mascarene Idands. — The bot-
any of the great island of Madagascar has been perhaps more
thoroughly explored than that of the opposite coasts of Africa,
so that its peculiarities may not be really so great as they now
appear to be. Yet there can be no doubt of its extreme richness
and grandeur, its remarkable speciality, and its anomalous exter-
nal relations. It is characterized by a great abundance of forest
trees and shinibs of peculiar genera or species, and often adorned
with magnificent flowers. Some of these are allied to African
forms, others to those of Asia, and it is said that of the two af-
finities the latter preponderates. But there are also, as in the an-
imal world, some decided South American relations, while others
point to Australia, or are altogether isolated.
Among the most prominent characteristics of the Madagascar
flora is the possession of a peculiar and isolated family, Chlse-
naceoe, allied somewhat to the balsams, but presenting very anom-
alous characters. It consists of four genera and a number of spe-
cies all entirely confined to the island. They are handsome trees
or shrubs, mostly with showy red flowers. One of them, Rho-
dolcEna altivola, is a semi-scandent shrub with magnificent cam-
panulate flowei*s the size of a camellia, and of a brilliant purple
404
ISLAND LIFE.
rPjutr n.
color. Tlie genns Chrysopia consists of large forest trees with
Bpreading crowns adorned with umbels or corymbs of lai^ pnr-
ple flowers. It belongs to the Clusiaeea?, nnd is most nearly al-
lied to tlie Soatb American genus Moronobea. Tbe Colvillea, a
peculiar genus of Leguminosie, is a tree with splendid scarlet
flowers; and there are a large number of other peculiar genera
more or less remarkable. Combretacese with splendid flowers
iibotind in l^ladagascar itself, though they arc rare in the Mss-
oarene Islands ; while the Bavenala, or " travellers tree ;'' the ex-
ti-aordinary lattiee-Icat-ed Ouvirandra; the Poitieianrt r-j^ia, oae
of the most gorgeous of flowering trees; and the long-spurred
Angraieitm. senquljiedaU, one of the most elegant and remarkable
of orchids, are among its vegetable wondere."
Of the flora of the smaller Madagasearian islands wo possess
A much fuller account, owing to the recent publication of Mr.
Baker's "Flora of the Mauritius and the Seychelles," including
also ilodrigiiez. The tutal number of species in this flora is 1058,
more than half of which (536) are exclusively Mascarenc — that
i*, found only in some of the islands of the Madagascar group,
while nearly a third (304) are ondemic or confined to single iel-
ands. Of the wide-spread plants, fiO are found in Africa but
not in Asia, and 86 in Asia but not in Africa, showing similar
Asiatic preponderance to what is said to ticcnr in Madagascar.
With tho genera, however, the proportions are different, for I
find by going through the whole of the generic distributions as
given by Mr. IJakcr, that out of tho 440 genera of wild plants
50 are endeniio, 22 nro Asiatic but not African, while 28 arc
African but not Asiatic. Tins implies that the more ancient
connection has been on tho side of Africa, white a more recent
immigration, shown by identity of species, has come from the
side of Asia ; and it is probable tliat when the flora of Madagas-
car is moro thoroughly worked out, the same or a still greater
African prepomlepaneo will be found in that island.
A few Mascarene genera arc found elsewhere only in South
America, Anstmlia, or Polynesiii; and there are also a consid*
' TIii> ikulcli of Ihn Horn of Mfldii^ii-cnr U tubrn cliioily ri-oni n ttriii of nrtldei
l>v M. fiiiiilo Bli.iu'l.iirU. In iIjb Rtew ilt4 iJ^jr Jfn«./*j, V..I. CI, (1872).
Chap.XIX] the MADAGASCAR GllOUP. 405
crable number of genera whoso metropolis is South America,
but which are represented by one or more species in Madagas-
car, and by a single often widely distributed species in Africa.
This fact throws light upon the problem oflfered by those mam-
mals, reptiles, and insects of Madagascar which now have their
only allies in South America, since the two cases would bo ex-
actly parallel were the African plants to become extinct. Plants,
however, are undoubtedly more long-lived specifically than ani-
mals, especially the more highly organized groups, and are less
liable to complete extinction through the attacks of enemies or
through changes of climate or of physical geography ; hence we
find comparatively few cases in which groups of Madagascar
plants have their ordy allies in such distant regions as America
and Australia, while such cases arc numerous among animals,
owing to the extinction of the allied forms in intervening areas,
for which extinction, as we have already shown, ample cause can
be assigned.
Curious Relations of Mascarene Plants. — Among the curious
affinities of Mascarene plants we have culled the following from
Mr. Baker's volume. Trochetia, a genus of Sterculiacese, has
four species in Mauritius, one in Madagascar, and one in the 1x5-
moto island of St. Ilelena. Mathurina, a genus of Turneraceip,
consisting of a single species peculiar to liodriguez, has its near-
est ally in another monotypic genus, Erblichia, confined to Cen-
tral America. Siegesbeckia, one of the Compositae, consists of
two species, one inhabiting the Mascarene Islands, the other
Peru. Labourdonasia, a genus of Sapotaceffi, has two species in
Mauritius, one in Natal, and one in Cuba. Nesogenes, belonging
to the verbena family, has one species in Rodriguez and one in
Polynesia. Mespilodaphne, an extensive genus of I^uraccffi, has
six species in the Mascarene Islands, and all the rest (about fifty
species) in South America. Nepenthes, the well-known pitcher-
plants, are found chiefly in the Malay Islands, South China, and
Ceylon, with species in the Seychelle Islands and in Madagascar.
Milla,a large genus of Liliaceae, is exclusively American, except
one species found in Mauritius and Bourbon. Agauria, a genus
of Ericaceae, is confined to the Mascarene Islands and the Cama-
roon Mountains in West Africa. An acacia found in Mauritius
406 ISLAND LIFE. [Part II.
and Bourbon {A, heterophylla) can hardly be separated specif-
ically from Acacia hoa of the Sandwich Islands. The genus
Pandanus, or screw-pine, has sixteen species in the three islands
— ^Mauritius, Rodriguez, and the Seychelles — all being peculiar,
and none ranging beyond a single island. Of palms there are
fifteen species belonging to ten genera, and all these genera are
peculiar to the islands. We have here ample evidence that
plants exhibit the same anomalies of distribution in these islands
as do the animals, though in a smaller proportion ; while they
also exhibit some of the transitional stages by which these anom-
alies have, in all probability, been brought about, rendering quite
unnecessary any other changes in the distribution of sea and land
than physical and geological evidence warrants.*
* It mny be interesting to botanists and to students of geograpliical distribution to
give here an enumeration of the endemic genera of the ** Flora of the Mauritius and
the Seychelles/' as they are nowhere separately tabulated in that work.
Aphloia (Bixaceo:) 1 sp., a shrub, Mauritius, Kodriguez, Seychelles, also
Madagascar.
Medusagyne (Ternstromiacete). 1 sp., a shrub, Seychelles.
Astiria (Sterculiaceie) 1 sp., a shrub, Mauritius.
Qnivisia (Meliaceae) 3 sp., shrubs, Mauritius (2 sp.), Rodriguez (I sp.),
also Bourbon.
Cossignya (Sapindnceac) 1 sp., a shrub, Mauritius, also Bourbon.
Hornea ** 1 sp., a shrub, Mauritius.
Stadtmannia ** 1 sp., a shrub, Mauritius.
Doratoxylon ** 1 sp., a shrub, Mauritius and Bourbon.
Gngnebina (Leguminosic) 1 sp., a shrub, Mauritius, also Madagascar.
Roussea (Saxitragacea;) 1 sp., a climbing shrub, Mauritius and Bourbon.
Tetrataxis (Lythraceai) 1 sp., a shrub, Mauritius.
Psiloxylon ** 1 sp., a shrub, Mauritius and Bourbon.
MathuVina (Tumeracea;) 1 sp., a shrub, Rodriguez.
Faetidia (Myrtaccffi) 1 sp., a tree, Mauritius.
Dnnais (liubiacca?) 4 sp., climbing shrubs, Mauritius (I sp.), Rodriguez
(I sp,), also Bourbon and Madagascar.
Fernelia '* 1 sp., a slnub, Mauritius and Rodriguez.
I'yrostria " 6 sp., shrubs, Mauritius (3 sp.), also Bourbon and
Madagascar.
Scyphochlamys '* 1 sp., a shrub, Rodriguez.
Myonima ** Jl sp., shrubs, Mauritius, also Bourbon.
Cylindroclino (Composita?) 1 sp., a shrub, Mauritius.
Monarrhenus *' 2 sp., shrubs, Mauritius, also Bourbon and Mada-
gascar.
Fanjasia ** 3 sp., shrubs, Mauritius, also Bourbon and Mada-
gascar.
Iletcrochaenia (Campanulacca*). 1 sp., a shrub, Mauritius, also Bourbon.
Tauulepi? (Asclepiadacexc) 1 sp., a climber, Rodriguez.
Decaucma ** 1 sp., a climber, Mauritius, also Madagascar.
Chap. XIX.] THE MADAGASCAR GllOUP. 407
Fragmentary Character of the Mascarene Flora, — Al though
the peculiar character and affinities of the vegetation of these
islands are sufficiently apparent, there can be little doubt that we
only possess a fragment of the rich flora which once adorned
them. The cultivation of sugar and other tropical products has
led to the clearing-away of the virgin forests from all the low-
lands, plateaus, and accessible slopes of the mountains, so that
remains of the aboriginal woodlands only linger in the recesses
of the hills, and numbers of forest-haunting plants must inevi-
tably have been exterminated. The result is that nearly three
hundred species of foreign plants have run wild in Mauritius,
and have in their turn helped to extinguish the native species.
Nicodemia (Lognnincete) 2 sp., shrubs, Mnurititis (1 sp.), also Comoro Islands
niid Madagascar.
Bryodes (Serophulariaceje) 1 sp., herb, Mauritius.
liadamaca *^ 2 sp., herb, Seychelles (1 sp.) and Madagascar.
Colea (Rignoniaceae) 10 sp., Mauritius (I sp.), Seychelles (1 sp.), also
Bourbon and Madagascar. (Shrubs, trees, or
climbers.)
Obetia (Crticaces) - sp* shrubs, Mauritius, Seychelles, and Madagascar.
Bosquiea (Moreae) 3 sp., trees, Seychelles (1 sp.), also Madagascar.
Monimia (Moniminceae) 3 sp., trees, Mauritius (2 sp.), also Bourbon.
Cynorchis (Orchideie) 3 sp., herb, ter., Mauritius.
Amphorchis '^ 1 sp** herb, ter., Mauritius, also Bourbon.
Amottia ** 2 sp., herb, ter., Mauritius, also Bourbon.
Aplostellis ** 1 sp., herb, ter., Mauritius.
Cryptopiis ** 1 sp., herb, Epiphyte, Mauritius, also Bourbon and
Madagascar.
Lomatophvllum (Liliaceie) 3 sp., shrubs (succulent), Mauritius, also Bourbon.
Lodoicca (Palma;) 1 sp., tree, Seychelles.
Latauia '* 3 sp., trees, Mauritius (2 sp.), Rodriguez, also Bour-
bon.
Hyophorbe ** 3 sp., trees, Mauritius (2 sp.), Rodriguez, also Bour-
bon.
Dictyosperma ** 1 ^Pm ^r^^t Mauritins, Rodriguez, also Bourbon.
Acantiiophoenix ** - sp., trees, Mauritius, also Bourbon.
Deckenia ** 1 «*?•» tree, Seychelles.
Ncphrosperma ** 1 sp., tree, Seychelles.
lioscheria *' 1 8P-> tree, Seychelles.
Verschaffeltia ** 1 ^Pm tree, Seychelles.
Sfevensonia ** 1 ^Pm tree, Seychelles.
Ocliropieris (Filices) 1 pp., herb, Mauritius, also Bourbon and Madagas-
car.
Among the curious features in this list are the great number of endemic shrubs in
Mauritius, and the remarkable assemblage of five endemic genera of palms in tlie
Seychelle Islands. We may also notice that one palm {Latania Loddigesti) is con-
fined to Round Island and two other adjacent islets, offering a singular analogy Co
the peculiar snake also found there.
ISLAND LIFE.
[PiMU.
In the Sej'cbellea, too, the indigenous flora has hecn almost en-
tirely (leetroyed in most of tlie ielaiicis, although tlie peculiar
palms, from their longevity and comparative hardiness, have
survived. Mr. Geoifrey Nevill tells na that nt Mahe and most
of the other islands visited by liim, it was only in a few spots
near the summits of the hills that he could perceive any remains
of the ancient fiora. Pineapples, cinnamon, bamboos, and other
plants have obtained a firm footing, covering large tracts of
country, and killing the more delicate native tlowei's and ferns.
The pineapple, especially, grows almost to tlio tops of the
moantaioB. Where the timber and shrubs have been destroyed,
the water falling on the surface immediately cuts channels, rune
off rapidly, and caueee the land to become dry and arid ; and the
same effect is largely seen both in Mauritius and Bourbon,
where, originally, dense forest covered the entire surface, and
perennial moisture, with its ever-accompanying luxuriance of
vegetation, prevailed.
Flora of Madagascar Allied to that of South Africa. — In my
" Geognipliieal Distribution of Animals," I have rcmarlied on
the relation between the insects of Madagascar and those of
south temperate Africa, aud have speculated on a great aouthern
extension of the continent at the time when Madagascar was
united with it. As supporting this view I now quote Mr. Hent-
ham's remarks on the Compositte. He eays, "The connections
of the Mascarene endemic Compositie, especially those of Mada-
gascar itself, are eminently with the southern and subtropical
African races ; the more tropical races, Plucheineee, etc., may be
rather more of an Asiatic type." lie further says that the Com-
posite flora is almost as strictly endemic as that of the Sandwich
Islands, and that it is much diversified, with evidences of great
antiquity, while it shows insular characteristics in the tendency
to tall shrubby or arborescent forma in several of the endemic or
prevailing genera.
PrejHmderaiic^ of Ferns in the Ma%carenc Flora. — A striking
character of the flora of these smaller Mascarene islands is the
great preponderance of ferns, and next to tliem of Oi-chideje,
The following figures arc taken from Mr. Baker's "Flora" for
Mauritius and the Seychelles, and from an estimate by M. Frap-
CiiAP.XIX.] THE MADAGASCAR GROUP. 409
pier of the flom of Bourbon given in Maillard's volume already
quoted :
Mauritius, etc. Bom bon.
Ferns 1G8 1 Ferns 240
Orchideo; 71) Orchideas 120
Gramineic CO
CyperaceiB G2
Rabiacexc r>7
Gramineie GO
Composita; GO
Jjeguminosa} 30
Eaphorbiacea: 4.'i i Rubiaccxe 24
Composita;. 43 Cyperaceae 24
Leguminosae 41 1 Euphorbiaceoe. 18
The cause of the great preponderance of ferns in oceanic isl-
ands has already been discussed in my book on " Tropical Nat-
ure ;" and we have seen that Mauritius, Bourbon, and Rodri-
guez must be classed as such, though from their proximity to
Madagascar they have to be considered as satellites to that great
island. The abundance of orchids may be in part due to analo-
gous causes. Their usually minute and abundant seeds would
be as easily carried by the wind as the spores of ferns, and their
frequent epiphytic habit affords them an endless variety of sta-
tions on which to vegetate, and at the same time removes them,
in a great measure, from the competition of other plants. When,
therefore, the climate is sufficiently moist and equable, and there
is a luxuriant forest vegetation, we may expect to find orchids
abundant on such tropical islands as are not too far removed
from other lands or continents from which their seeds might be
conveyed.
Concluding Remarks on Madagascar and the Mascarene Isl-
ands,— There is probably no portion of the globe that contains
wfthin itself so many and such varied features of interest con-
nected with geographical distribution, or which so well illus-
trates the mode of solving the problems it presents, as the com-
paratively small insular region which comprises the great island
of Madagascar and the smaller islands and island-grOups which
immediately surround it. In Madagascar we have a continental
island of the first rank, and undoubtedly of immense antiquity;
we have detached fragments of this island in the Comoros and
Aldabra ; in the Seychelles we have the fragments of another
very ancient island, which may perhaps never have been conti-
410
ISLAND LIFE.
[Pm
[lental ; in Muuritiiis, Eoiirbon, and Rodriguez we have three
iiiidonbtediy oceanic islands ; while in tlie extensive banks and
eoral reefs of Cargados, Saya de Maiha, the Chagos, and the Mal-
dive Isles we have indications of the submergence of many large
islands which may have aided in the transmission of organisms
from the Indian Peninsula. But between and around all these
islands we liave depths of 25LH> fathoms and upwards, which
renders it very improbable that there has ever been here a con-
tinuous land surface, at all events during the Tertiary or Sec-
ondary period of geolon:y.
It is most interesting and satisfactory to find that this conclu-
sion, arrived at solely by a study of the form of the sea-bottom
and the general principle of oceanic permanence, is fully snp-
ported by tie evidence of the organic productions of the several
islands; because it gives us contidenee in those principles, and
helps to supply us with a practical demonstration of them. We
find that the entire group contains just that amount of Indian
forms wliicli could well have passed from island to island ; that
many of these forms are slightly modified species, indicating
that the migration occurred during late Tertiary times; while
others are distinct genera, indicating a more ancient connection.
Bat in no one case do we fiud animaU which necessitate an actual
land-connection ; while the numerous Indian types of mammalia,
reptiles, birds, and insects, which must certainly have passed over
had there been sncli an actual land-connection, are totally want-
ing. The one fact which has been supposed to require such a
connection — the distribution of the lemurs^ — can be far more
naturally explained by a general dispersion of the group from
Europe, where we know it existed in Eocene times; and such
an explanation applies equally to the affinity of the Insectivora
of Madagascar and Cuba, the snakes (I lerpetodryas, etc.) of
Madagascar and America, and the lizards (Cryptoblepharns) of
Manritius and Australia, To suppose, in all these cases, and in
many others, a dii-ect land-connection is really abenrd, because
we havo the evidence afforded by geology of wide differences
of distribution directly wn pass lieyond the most recent deposits;
and when wo go back to Mesozoic, and still more to Palfeozoic,
times, the majority of the groups of animals and plants appear
Chap. XIX.] THE MADAGASCAR GROUP. 411
to have liad a world-wide range. A large number of our Euro-
pean Miocene genera of vertebrates were also Indian or African,
or even American ; the South American Tertiary fauna con-
tained many European types ; while many Mesozoic reptiles and
mollusca ranged from Europe and North America to Australia
and New Zealand.
By direct proof (the occurrence of wide areas of marine de-
posits of Eocene age), geologists have established the fact that
Africa was cut off from Europe and Asia by an arm of the sea
in early Tertiary times, forming a large island-continent. By
the evidence of abundant organic remains we know that all the
types of large mammalia now found in Africa (but which are
absent from Madagascar) inhabited Europe and Asia, and many
of them also North America, in the Miocene period. At a still
earlier epoch Africa may have received its lower types of mam-
mals— lemurs, insectivora, and small carnivora, together with
its ancestral struthious birds, and its reptiles and insects of
American or Australian affinity ; and at this period it was joined
to Madagascar. Before the later continental period of Africa,
Madagascar had become an island ; and thus, when the large
mammalia from the northern continent overran Africa, they
were prevented from reaching Madagascar, which thenceforth
was enabled to develop its singular forms of low-type mamma-
lia, its gigantic ostrich-like j^lpyornis, its isolated birds, its re-
markable insects, and its rich and peculiar flora. From it the
adjacent islands received such organisms as could cross the sea;
while they transmitted to Madagascar some of the Indian birds
and insects which had reached them.
The method we have followed in these investigations is to ac-
cept the results of geological and palseontological science, and
the ascertained facts as to the powere of dispereal of the various
animal groups ; to take full account of the laws of evolution as
affecting distribution, and of the various ocean depths as imply-
ing recent or remote union of islands with their adjacent conti-
nents ; and the result is that wherever we possess a sufficient
knowledge of these various classes of evidence, we find it possi-
ble to give a connected and intelligible explanation of all the
most striking peculiarities of the organic world. In Madagas-
112
ISLAND LIFE.
CPJOT It
oar we liave iiiKlovibtedly one of tlie most difficult of these prob-
lems; but we have, I tliink, fnirlj met and conquered most of
its difficulties. The coini)le.xUj of the organic relations of this
igland is due jwirtly to its having derived its animal forms from
two distinct sources — from one continent throngh a direct land-
connection, and from another by ine.ana of intervening islands
now eulimerged ; but mainly to the fact of its having been BCp-
arated from a continent which is now, zoologically, in a very dif-
ferent condition from what it was at the time of the separation ;
and to its having been thus able to preserve a number of types
which may date back to the Eocene, or even to the Ci'etaceous,
period. Sonic of ihcse types liavo become altogether extinct
elsewhere ; others have spread far and wide over the globe, and
have survived only in a few remoto countries, and especially in
those which have been more or less secured by their isolated po-
sition from the incursions of the more highly developed forms
of later times. This explains why it is that the nearest allies
of the Madagascar fauna and flora are now so often to be found
in South America or Australia — countries in which low forms
of mammalia and birds still largely prevail — it being on account
iif the long-continued isolation of all these countries that simi-
lar forms (descendants of ancient types) are preserved in tliem.
Had the numerous suggested continental extensions connecting
these remote continents nt various geological periods been resli-
ties, the result wonld havo been that all these interesting archaic
forms, all these helpless insular types, would long ago have been
exterminated, and one comparatively monotonous fauna have
reigned over the whole earth. So far from explaining the anom-
alous facts, the alleged continental extensions, had they existed,
would have left no such fiicfs to be explained.
i
Chap. XX.] CELEBES. 413
CHAPTER XX.
ANOMALOUS ISLANDS: CELEBES.
Anomalous Relations of Celebes. — Physical Featnres of the Island. — Zoological
Character of the Islands around Celebes. — The lilalnvan and Australian Banks. —
Zoology of Celebes: Mararaalia. — Probable Derivation of the Mammals of Cele-
bes.— Birds of Celebes. — Bird-types Peculiar to Celebes. — ^Celebes not strictly a
Continental Island. — Peculiarities of the Insects of Celebes. — Himalayan Types
of Birds and Butterflies in Celebes. — Peculiarities of Shape and Color of Celebe-
sian Butterflies. — Concluding Bemarks. — Appendix on the Birds of Celebes.
The only other islands of the globe which can be classed as
"ancient continental" are the larger Antilles (Cuba, Hayti, Ja-
maica, and Porto Kico), Iceland, and perhaps Celebes. Tlie An-
tilles have been so fully discussed and illustrated iu my former
work, and there is so little fresh information about them, that
I do not propose to treat of them here, especially as they fall
short of Madagascar in all points of biological interest, and offer
no problems of a different character from such as have already
been sufficiently explained.
Iceland, also, must apparently be classed as belonging to the
"Ancient Continental Islands," for though usually described as
wholly volcanic, it is more probably an island of varied geolog-
ical structure buried under the lavas of its numerous volcanoes.
But of late years extensive Tertiary deposits of Miocene age
have been discovered, showing that it is not a mere congeries
of volcanoes ; it is connected with the British Islands and with
Greenland by seas less than 500 fathoms deep; and it possesses
a few mammalia, one of which is peculiar, and at least three pe-
culiar species of birds. It was therefore almost certainly united
with Greenland, and probably with Europe by way of Britain,
in the early part of the Tertiary period, and thus afforded one
of the routes by which that intermigration of American and
European animals and plants was effected which we know oc-
414: ISLAND LIFE. [Part IL
cuiTed during some portion of the Eocene and Miocene periods,
and probably also in the Pliocene. The fauna and flora 'of this
island are, however, so poor, and offer so few peculiarities, that
it is unnecessary to devote more time to their consideration here.
There remains the great Malay island Celebes, which, owing
to its possession of several large and very peculiar mammalia,
must be classed, zoologically, as "ancient continental," but
whose central position and relations both to Asia and to Aus-
tralia render it very difficult to decide in which of the primary
zoological regions it ought to be placed, or whether it has ever
been united with either of the great continents. Although I
have pretty fully discussed its zoological peculiarities and past
history in my " Geographical Distribution of Animals," it seems
advisable to review the facts on the present occasion, more es-
pecially as the systematic investigation of the characteristics of
continental islands we have now made will place us in a better
position for determining its true zoo-geographical relations.
Physical Features of Cehhes, — This large and still compara-
tively unexplored island is interesting to the geographer on ac-
count of its remarkable form, but much more so to the zoologist
for its curious assemblage of animal forms. The geological
structure of Celebes is almost unknown. The extremity of the
northern peninsula is volcanic; while in the southern peninsula
there are extensive deposits of a crystalline limestone, in some
places overlying basalt. Gold is found in the northern penin-
sula and in the central mass, as well as iron, tin, and co])per in
small quantities ; so that there can be little doubt that the moun-
tain-ranges of the interior consist of ancient stratifted rocks.
It is not yet known whether Celebes is completely separated
from the surrounding ijjlands by a deep sea, but the facts at our
command render it probable that it is so. The northern and
eastern portions of the Celebes Sea have been ascertained to be
from 2000 to 2(500 fathoms deep, and such depths ma}^ extend
over a considerable portion of it, or even be much exceeded in
the centre. In the Molucca passage a single sounding on the
Gilolo side gave 1200 fathoms, and a large part of the ilolucca
and Baiula Seas probably exceeds 2000 fathoms. The southern
portion of the Strait of ^lacassar is full of coral reefs, and a
Cmr. XX.]
CELEBES.
415
bIiiiIIow Bea of less than 100 fatlioins extends from Borneo to
within about furtj miles of tlic western promontory of Celebes ;
but further iiortii there is deej) water close to the sliore, iind it
Tlia depth ofKU iiahown by ihree tinia; tlie ll];lil«9[ iiiitienlitig IcM ihnn 100 Tiitli.
iiin«. tlie BiFilium iiii( lets ilmn lOOtl fuilioniR, aiiJ tlie tlortL tiul more tlinii JOUO
laiLoms. Tlie ligurea iboiv depth* iu fiulioms,
soems probable that a deep channel extends quite through the
strait, which has, no doubt, been miidi shallowed hy the dcpoails
from the great Bornean rivers as well as by t\yose of Celebes
itself. Southward again, tlie chain of volcanic islands from Bali
416
ISLAND UFE.
[P*« W.
to Timor appear to rise out of a deep ocean, the few Eoundings
wo possess showing depths of from 670 to 1300 fathonia almost
close to their northern shores. We seem justified, therefore, in
concluding that Celebes is entirety surrounded hy a deep sea,
which has, however, become partially filled np by river deposits,
by volcanic upheaval, or by coral reefs. Such shallows, whei-c
they exist, may thei-efore he due to antiquity and isolation, in-
Etead of being indications of a former union with any of the
surrounding i&lnnds.
Zoolof/ical Character of the fffamh around Cdeheg. — In oi-der
to have & clear conception of the peculiar character of the Cele-
bcsian fauna, we must take into account that of the surrounding
countries from which we may suppose it to liave received ini-
migrants. Tliese we may divide broadly into two groups, those
on tlie west belonging to the Oriental region of our zoological
geography, and those on the east belonging to the Australian
region. Of the first group Borneo is a typical repi-esentativo;
and from its proximity and the extent of its opposing coasts it
is the island wliich we should expect to show most resemblance
to Celebes. We have already seen that the fauna of Borneo is
essentially the same as that of Southern Asia, and that it is ex-
cessively rich in all the Malayiin types of mammalia and birds.
Java and Bali closely i-escmble Borneo in general character,
though somewhat less rich and with several peculiar forms;
while the Philippine Islands, though very much poorer, and
Avitb n greater amount of speciality, yet exhibit essentiftl!y the
same character. These islands, taken as a whole, may be de-
scribed as having a fauna almost identical with that of Southern
Asia; for no family of mammalia is found in llie one which is
absent from the other, and the same may be said, with very few
and unimportant exceptions, of the birds; while hundreds of
genera and of species are common to both.
In the islnnds east and south of Celebes — the MoluccjiSj New
Oninoa, and the Timor group from Lonibok eastward — we find,
on the other hand, the most wonderful contrast in the forms of
life. Of twenty-seven families of terrestrial mammals found in
the great Malay islands, all have disappeared but fonr, and of
these it is doubtfnl whether two have not been introduced by
Chap. XX.J CELEBES. 417
man. We also find here four families of Marsupials, all totally
unknown in the western islands. Even birds, though usually
more widely spread, show a corresponding difference, about
eleven Malayan families being quite unknown east of Celebes,
where six new families make their appearance which are equally
unknown to the westward.'
We have here a radical difference between two sets of islands
not very far removed from each other, the one set belonging
zoologically to Asia, the other to Australia. The Asiatic or
Malayan group is found to be bounded strictly by the eastward
limits of the great bank (for the most part less than fifty fath-
oms below the surface) which stretches out from the Siamese
and Malayan peninsulas as far as Java, Sumatra, Borneo, and
the Philippines. To the east another bank unites New Guinea
and the Papuan Islands as far as Aru, Mysol, and Waigiou, with
Australia; while the Molucca and Timor groups are surrounded
by much deeper water, which forms, in the Banda and Celebes
seas, and perhaps in other parts of this area, great basins of
enormous depths (2000 to 3000 fathoms, or even more) en-
closed by tracts under 1000 fathoms, which separate the basins
from each other and from the adjacent Pacific and Indian
oceans (see map). This peculiar formation of the sea-bottom
probably indicates that this area has been the seat of great local
upheavals and subsidences; and it is quite in accordance with
this view that we find the Moluccas, while closely agreeing with
New Guinea in their forms of life, yet strikingly deficient in
' Families of Malayan Birds not Found
in Islands East of Celebes.
Troglodytidse.
Sittidae.
Pandas.
Liotrichidse.
PbjUornithidie.
EurylsemidiB.
Picidffi.
Indicatoridn.
Megalieroidfle.
Trogonidie.
Phasianidie.
Families of Moluccan Birds not Fonnd
in Islands West of Celebes.
ParadiseidsB.
Meliphagidje.
CacatuidsB.
Platycercidae.
Trichoglossidxe.
Nestoiidie.
27
418
ISLAND LlFi:.
rll.
many important groups, and exhibiting an altogetlier poverty-
stricken appearance as regards tlie liigher animals. It is » sug-
gestive fact that the Philippine Ishinds bear a» exactly parallel
ixjlation to Borneo, being equally deficient in many of the higher
groups; and hero too, in the Sooloo Sea, we find a similar en-
closed basin of great depth. Hence wo may in both cases con-
nect, on the one hand, tlie extensive area of land surface and of
adjacent slitillow sea with a long period of stability and a con-
sequent I'icb development of the forms of life; and, on the
other hand, a highly broken land surface, with the adjacent seas
of gre.1t but very unequal depths, with a period of disturbance,
probably involving extensive Bubniersions of the land, resulting
in a scanty and fragmentary vertebrate fauna.
Zoolofjij of Cdfhes. — The zoology of Celebes differs so remark-
ably from that of both the great divisions of the archipelago
above indicated that it is very diflSenlt to decide in which to
place it. It possesses only about sixteen species of terrestrial
niauimalia,so tliat it is at once distinguished from Borneo and
Java by its extreme poverty in this class. Of this small number
fonr belong to the Molncean and Australian fauna — there being
two marsnpiuls of the genus Cnsctis, and two forest rats said to
bo allied to Australian types.
The remaining twelve species are, generally speaking, of Ma-
layan or Asiatic types, but some of them arc so peculiar that
they have no near allies in any part of the woild ; while the
rest are of the ordinary Malay type, or even identical with Ma-
layan species, and some of these may be recent introductions
through Iniinan agency. These twelve apecies of Asiatic typo
will be now enumerated. They eoueist of five peculiar squirrels
— a group imknown farther east; a peculiar species of wild-pig;
ft deer bo closely allied to the Cervua /n'jipehp/ius of IJomeo
that it may well have been introduced by man both here and in
the Moluccas; a civet, Viivrra tangalnnija, common in all the
Malay islands, and also perhaps introduced ; the curious Malayan
tarsier{7rtraiw**^jet'//'um),said to bo only found in a small island
oS the coast ; and, besides these, three remarkable animals, all of
large size, and all qnite unlike anything found in the Malay Isl-
ands or even in Asia. These arc a black and almost tailless
Chap. XX.] CELEBES. 419
baboon-like ape (Oj/nopit/iecus nigrescens); an antelopean buf-
falo {Anoa depr€88icomu\ and the strange babirusa {Babirusa
alfurus).
None of these three animals last mentioned have any close
allies elsewhere, and their presence in Celebes may be considered
the crucial fact which must give us the clew to the past history
of the island. Let us, then, see what they teach us. The ape
is apparently somewhat intermediate betw^een the great baboons
of Africa and the short-tailed macaques of Asia, but its ci*anium
shows a nearer approach to the former group in its flat project-
ing muzzle, large superciliary crests, and maxillary ridges. The
anoa, though anatomically allied to the buffaloes, externally
more resembles the bovine antelopes of Africa; while the
babirusa is altogether unlike any other living member of the
swine family, the canines of the upper jaws growing directly
upward like horns, forming a spiral curve over the eyes, instead
of downward, as in all other mammalia. An approach to this
peculiarity is made by the African wart-hogs, in which the upper
tusk grows out laterally and then curves up ; but these animals
are not otherwise closely allied to the babirusa.
ProbahU Derivation of the Mammals of Celebes. — It is clear
that we have here a group of extremely peculiar, and in all
probability very ancient, forms, which have been preserved to
us by isolation in Celebes, just Jis the monotremes and mar-
supials have been preserved in Australia, and so many of the
lemurs and Insectivora in Madagascar. And this compels us
to look upon the existing island as a fragment of some ancient
land, once perhaps forming part of the great northern continent,
but separated from it far earlier than Borneo, Sumatra, and Java.
The exceeding scantiness of the mammalian fauna, however, re-
mains to be accounted for. We have seen that Formosa, a much
smaller island, contains more than twice as many species ; and
we may be sure that at the time when such animals as apes
and buffaloes existed, the Asiatic continent swarmed with varied
forms of mammals to quite as great an extent as Borneo does
now. If the portion of separated land had been anything like
as large as Celebes now is, it would certainly have preserved a
far more abundant and varied fauna. To explain the facts we
420
ISLAND LIFE.
[P*nr n.
have the choice of two theories — either that the origiual island
has since its scparatiou been gieatly reduced by snbiuersion, eo
as to lead to the extinction of most of the higher land animals;
or that it originally formed part of an independent land stretch-
ing eastward, and was only united with the Asiatic continent
for a short period, or perhaps even never united at all, but so
connected by intervening islands separated by narrow straits
that a few mammals might find tlieir way across. The latter
supposition apjtears best to explain the facts. The three animals
in question are such as might readily pass over narrow straits
from island to island ; and we are thus better enabled to under-
stand the complete absence of the arboreal monkeys, of the In-
Bcctivora, and of tlie very numerous and varied Carnivora and
llodents of Borneo, all of which are entirely uii represented in
Celebes by any peculiar and ancient forms except the squirrels.
The question at issue can only be finally determined by geo-
logical iuvosligations. If Celebes has once formed part of Asia,
and participated in its rich mammalian fauna which has been
since destroyed by submergence, then some remains of this fauna
must certainly be preserved in caves or late Tei'tiary deposits,
and proofs of the submergence itself will be found when sought
for. If, on the other hand, the existing animals fairly represent
those which bare ever reached the island, then no sueb remains
will bo discovered, and there need bo no evidence of any great
and extensive subsidence in late Tertiary times.
Birth of Cdehes. — Having thus clearly placed before us the
problem presented by the mammalian fauna of Celebes, we may
proceed to see what additional evidence is afforded by the birds,
and any other groups of which we have sufficient information.
About 164 species of true land birds are now known to inhabit
tlie island of Celebes itself. Considerably more than half of
these (94 species) are peculiar to it ; 29 ai-o found also in Borneo
and the other Malay islands, to which thoy specially belong;
while IG are common to the Moluccas or other islands of the
Australian region ; the remainder being species of wide range,
and not characteristic of either division of the archipelago. We
have here a large prepontlerance of Western over Eastern species
of birds inhabiting Celebes, though not to qnite so great an ex-
CiiAF. XX.] CELEBES. 421
tent as in the mammalia; and the inference to be drawn from
tills fact is, simply, that more birds have migrated from Borneo
than from the Moluccas — which is exactly what wo might ex-
pect, both from tlie gi'eater extent of the coast of Borneo oppo-
site that of Celebes, and also from the much greater richness in
species of the Bornean than the Moluccan bird fauna.
It is, however, to the relations of the peculiar species of Cele-
besian birds that we must turn in order to ascertain the origin
of the fauna in past times ; and we must look to the source of
the generic types which they represent to give us this informa-
tion. The ninety-four peculiar species above noted belong to
about sixty-six genera, of which about twenty-three are common
to the whole archipelago, and have therefore little significance.
Of the remainder, twelve are altogether peculiar to Celebes ;
twenty-one are Malayan, but not Moluccan or Australian ; while
ten are Moluccan or Australian, but not Malayan. This propor-
tion does not differ much from that afforded by the non-peculiar
species ; and it teaches us that, for a considerable period, Cele-
bes has been receiving immigrants from all sides, many of which
have had time to become modified into distinct representative
species. These evidently belong to the period during which
Borneo, on the one side, and the Moluccas, on the other, have oc-
cupied very much the same relative position as now. There re-
main the twelve peculiar Celebesian genei-a, to which we must
look for some further clew as to the origin of the older portion
of the fauna ; and as these are especially interesting, we must
examine them somewhat closely.
Bird-types Peculiar to Celebes, — First we have Artamides,
one of the Campephagina?, or caterpillar -shrikes — a not very
well-marked genus, and which may have been derived either
from the Malayan or the Moluccan side of the archipelago.
Two peculiar genera of kingfishers — Monachalcyon and Cittura
— seem allied, the former to the wide-spread Todiramphus and
to the Caridonax of Lombok, the latter to the Australian Meli-
dora. Another kingfisher, Ceycopsis, combines the characters
of the Malayan Ceyx and the African Ispidina, and thus forms
an example of an ancient generalized form analogous to what
occurs among the mammalia. Streptocitta is a peculiar form
422
ISLAND LIFE.
[Vktn II.
allied to the magpies ; wliilc Basilornis {found also in Ceram),
EnodeE, and Sciesirostrum are very peculiar starlings, the latter
altogether unlike any other bird, and perhaps forming a diBtinet
8ub-familj-. Meropogon is a peculiar bee-eater, allied to the
Malayau Nyctiornis ; Rhamphocoecyx is a modification of PhiB-
iiicophaes, a Maiayau genus of cuckoos ; Prioniturus (found also
in the Philippines) is a genus of parrots distinguished by raquet-
formed tail-feathers, attogetlier unique in the order; while Mega-
cephalon is a remarkable and very isolated form of the Aus-
ti-alian Megapodiida?, or mound-builders.
Omitting those whose affinity may be pretty clearly traced to
groups still inhabiting the islands of the western or the eastern
half of the archipelago, wo find four birds which have no near
allies at all, but appear to be cither ancestral forms, or extreme
modifications, of Asiatic or African birds — Basilornis, Euodes,
Scissi rostrum, Ceycopsis, Tlieso may fairly be associated wi(h
the baboon-ape, auoa, and Imbirusa, ns indicating extreme antiq-
uity and some communication with the Asiatic continent at a
period when the forms of life and their geographical distribu-
tion differed considerably from what they are at the present
time.
But here again we meet with exactly the same difiiculty as in
the mammalia, in the comparative poverty of the types of birds
now inhabiting Celebes. Although the preponderance of affin-
ity, especially in the case of its more ancient and peculiar forms,
ia undoubtedly with Asia rather than with Australia, yet, stitl
mora decidedly than in the case of the mammalia, are we forbid-
den to suppose that it ever formed a part of the old Asiatic con-
tinent, on account of the toto^ absence of so many important and
extensive groups of Asiatic birds. It is not single species or
even genera, hut whole families, that are thus absent, and among
them families which are pre-eminently characteristic of all trop-
ical Asia. Such are the Tinialiidio, or babblers, of which there
arc twelve genera in Borneo and nearly thirty genera in the
Oriental Regioii, but of which one species only, hardly distin-
guishable from a Malayan form, inhabits Celebes; the Phyllor-
nithidfc, or green hulhnls, and the Pycnonotidje, or bulbnls,
both absolutely ubiquitous in tropical Asia and Malaya, but uu-
Chap. XX.] CELEBES. 423
known in Celebes; tlie Enrylsemidfie, or gapers, found every-
where in the great Malay islands; the Megalsemidse, or barbets;
the Trogonidse, or trogons; and the Fhasianidse, or pheasants;
all pre-eminently Asiatic and Malayan, but all absent from Cel-
ebes, with the exception of the common jungle- fowl, which,
owing to the passion of Malays for cock-fighting, may have been
introduced. To these importsint families may be added Asiatic
and Malayan genera by the score ; but, confining ourselves to
these seven ubiquitous families, we must ask, Is it possible that,
at the period when the ancestore of the peculiar Celebes mam-
mals entered the island, and when the forms of life, though dis-
tinct, could not have been quite unlike those now living, it could
have actually formed a part of the continent without possessing
representatives of the greater part of these extensive and impor-
tant families of birds ? To get rid altogether of such varied and
dominant types of bird-life by any subsequent process of sub-
mersion is more difficult than to exterminate mammalia ; and we
are therefore again driven to our former conclusion — that the
present land of Celebes has never (in Tertiary times) been united
to the Asiatic continent, but has received its population of Asi-
atic forms by migration across narrow straits and intervening isl-
ands. Taking into consideration the amount of affinity, on the
one hand, and the isolation, on the other, of the Celebesian fauna,
we may probably place the period of tliis earlier migration in
the early part of the latter half of the Tertiary period ; that is,
in middle or late Miocene times.
Celebes not iSt7n<:tly a Continental Island, — A study of the
mammalian and of the bird fauna of Celebes thus leads us in
both cases to the same conclusion, and forbids us to rank it as a
strictly continental island on the Asiatic side. But facts of a
very similar character are equally opposed to the idea of a for-
mer land-connection with Austmlia or New Guinea, or even
with the Moluccas. The numerous marsupials of those coun-
tries are all wanting in Celebes, except the phalangers of the
genus Cuscus, and these arboreal creatures are very liable to be
carried across narrow seas on trees uprooted by earthquakes or
fioods. The terrestrial cassowaries are equally absent ; and thus
we can account for the presence of all the Moluccan or Austra-
iU
ISLASD LIFE.
tPABT U.
lian types actually found in Celebes without supposing nny land-
connection on this side during the Tertiary period. Tlie pres-
ence of the Celebes ape in the ir^Iaiid of Batchian, and of the
baltirusa in Bouru, can bo Buliiciently explained by a eoniewliat
closer approximation of the respective lands, or by a few inter-
vening islands which Lave since disappeared, or it may even be
due to human agency.
If the explanation now given of the peculiar features present-
ed by the fauna of Celebes be the correct one, wc are fully jus-
tified in classing it as an "anomalous island,'' since it jiossesses
a small but very remarkable mammalian fauna, without ever
having been directly united witli any continent or extensive
land ; and, both by what it lias and what it wants, occupies bucIi
an exactly intermediate position between the Oriental and Aus-
tralian regions that it will perhaps ever remain a mere matter
of opinion with which it should properly be associated. Foiin-
ing, as it does, the western limit of such typical Australian
groups as the marsupials among ninuimalia, and the Triehoglos-
sida; and Hclipbagidie among birds, and being so strikingly de-
ficient i[i all the more characteristic Oriental families and genera
of both classes, I have always placed it in the Australian licgion ;
but it may perhaps with equal propriety he left ont of both till
a further knowledge of its geology enables ns to determine its
early history with more precision.
Peculiariti^ of the Jmt'cta of CelAes. — The only other class
of animals in Celebes of which we have a tolerable knowledge
is that of insects, among which we meet with peculiarities of a
vety remarkable kind, and such as are found in no other island
on the globe. Having already given a full account of some of
these peculiarities in a paper read before the LinntFan Society,
republished in my " Contributions to the Tlieory of Natural Se-
lection," while others have been discussed in my "Geographical
Distribution of Animals" (Vol. I,, p. 434), I will hero only briefly
refer to them in order to see whether they accord with, or re-
ceive any explanation from, the somewhat novel view of the
past liistory of the island here advanced.
The general distribution of the two best-known groups of in-
sects— tlie buttertliea and the beetles — agrees very closely witii
Chap. XX.] CELEBES. 425
that of the birds and mammalia, inasmnch as Celebes forms the
eastern limit of a number of Asiatic and Malayan genera, and at
the same time the western limit of several Moluecan and Aus-
tralian genera — the former perhaps preponderating, as in the
higher animals.
Himalayan Types of Birds and Butterflies in Celebes. — A
curious fact of distribution, exhibited both among butterflies
and birds, is the occurrence in Celebes of species and genera
unknown to the adjacent islands, but only found again when
we reach the Himalayan Mountains or the Indian Peninsula.
Among birds we have a small yellow flycatcher {Myialestes
helianthea)^ a flower-pecker {Pachyglossa aureolimhata\ a finch
{Munia brumieiceps\ and a roller {Cor ados Temminckii)^ all
closely allied to Indian (not Malayan) species — all the genera
except Munia being, in fact, unknown in any Malay island.
Exactly parallel cases are two butterflies of the genera Dichor-
rhagia and Euripus, which have very close allies in the Hima-
layas, but nothing like them in any intervening country. These
facts call to mind the similar case of Formosa, where some of its
birds and mammals occurred again, under identical or closely al-
lied forms, in the Himalayas ; and in both instances they can
only be explained by going back to a period when the distribu-
tion of these forms was very different from what it is now.
Peculiarities of Shape and Color in Celebesian Butterflies. —
Even more remarkable are the peculiarities of shape and color
in a number of Celebesian butterflies of different genera. These
are found to vary all in the same manner, indicating some gen-
eral cause of variation able to act upon totally distinct groups,
and produce upon them all a common result. Nearly thirty spe-
cies of butterflies, belonging to three different families, have a
common modification in the shape of their wings, by which they
can be distinguished at a glance from their allies in any other
island or country whatever ; and all these are larger than the
representative forms inhabiting most of the adjacent islands.*
No such remarkable local modification as this is known to occur
* For ontline figures of the chief types of these butterflies, see my ** Malay Archi-
pelogo," Vol. I., p. 441, or p. 281 of the second edition.
426 ISLAND LIFE. [Part II.
in aoy other part of the globe ; and whatever may have been its
cause, that cause mnst certainly have been long in action, and
have been confined to a limited area. We have here, therefore,
another argument in favor of the long-continued isolation of
Celebes from all the surrounding islands and continents — an
hypothesis which we have seen to afford the best, if not the
only, explanation of its peculiar vertebrate fauna.
Concluding liemarks. — If the view here given of the origin
of the remarkable Celebesian fauna is correct, we have in this
island a fragment of the great eastern continent which has pre-
served to us, perhaps from Miocene times, some remnants of its
ancient animal forms. There is no other example on the globe
of an island so closely surrounded by other islands on every
side, yet preserving such a marked individuality in its forms of
life ; while, as regards the special features which characterize its
insects, it is, so far as yet known, absolutely unique. Unfortu-
nately, very little is known of the botany of Celebes, but it
seems probable that its plants will to some extent partake of the
speciality which so markedly distinguishes its animals; and
there is here a rich field for any botanist who is able to pene-
trate to the forest-clad mountains of its interior.
APPENDIX TO CHAFIER XX. 427
APPENDIX TO CHAPTER XX.
The following list of the land birds of Celebes and the ad-
jacent islands which partake of its zoological peculiarities, in
which are incorporated all the species discovered up to the
present year, has been drawn up from the following sources :
1. A List of the Birds Known to Inhabit the Island of Celebes. By Arthur, Vis-
count Walden, F.R.S. iTrans. ZooL Soc., 1872, Vol. VIII., pt. ii.)
2. Intorno al Gcnere Ilermotimia. (Rchb.) Note di Tomnuiso SalvadorL (A tit
della Reale Academia delle Scienze di Torino^ VoL X., 1874.)
3. Intorno n Due Collezioni di Ucelli di Celebes. Note di Tommaso Salvadori.
{Annul-: del Mm. Civ, di St. Nat. di Gtnova, Vol. VII., 1876.)
4. Beitrage zur Omitbologie von Celebes und Sangir. Von Dr. Friedrich Briiggc-
mann. Bremen, 1876.
it. Intorno a Due Piccole Collezioni di Ucelli di Isole Sanghir e di Tifore. Note di
Tommaso Salvadori. (Annali del Mus. Civ. di St. Nat, di 6'enora, Vol. IX.,
187G-77.)
C. Intonio alle Specie di Nettarinie delle Molucche e del Gruppo di Celebes. Note
di Tommaso Salvadori. (Atti della Reale Acad, delle Scienze di Torino^
Vol. XII., 1877.)
7. Dcscrizione di Tre Nuove Specie di Ucelli, e Note intorno ad altre poco conosci-
ulc delle Isole Sanghir. Tcr Tommaso Salvadori. (Loc. ci7.. Vol. XIII. ,
1878.)
8. Field Notes on the Birds of Celebes. By A. B. Meyer, M.D., etc. (Ibisj 1879.)
\K On the Collection of Birds made by Dr. Meyer during his Expedition to New
Guinea and some Neighboring Islands. By R. Boulder Sharpe. (Mitth. d.
kgl. Zool. Mus. Dresden, 1878. Heft 8.) New species from the Sula and
Sanghir Islands are descnbcd.
10. List of Birds from the Sula Islands (Elast of Celebes), >vith Descriptions of the
New Species. By Alfred Kussel WalUce, F.Z.S. (Proc, ZooL Soc., 1862,
p. 333.)
428
ISLAND LIFE.
LIST OF LAND BIRDS OF CELEBES.
N.B, — The Species marked with an ♦ are not included in Viscount Walden's Kst. For
these only, an authority is usually given.
Celebes.
Sulals.
SangUir I&
Range and Remarks.
TURDID^
1 . Geociclila erythronotn
2. Monticola solitario.
Sylviid^.
8. Cisticola cursitans
X
X
X
X
X
X
X (Meyer)
X
X
X
X
X
X
X
X
X (Meyer)
x'
X
X
X
X (Wall.)
X
X (Salv.)
Phil., China, Japan
Assam
4. ** Gray!
5. Acrocephalus orien talis.
♦(). ** insnlaris
7. Pratincola caprata
*8. Gerygone flaveola (Cab.).. .
TiMALIID/E.
y. Tt'icbostoma Celebense
Pycnonotid*.
♦10. Criniger longirostris (Wall.)
*11. ** aureus (Wrtld.). •• •
Oriolii).*:.
1 2. Oi iolus Celebensis
China, Japan
Moluccas
Asia, Java, Timor
(Near G.sulphurea,
Timor)
Orien tal gen us (near
Bouru sp.)
/V.or. nf O.rnrnnn.
* 1 3. * * formosus (Cab. )
*14. '* frontalis (Wall.)....
CAMrKPHAGID.*:.
15. Graucalus ntriccps
1 tiis^ Java)
X(Brugg.)(Var. of Philipp.
ep.)
1
Ceram. Flores
H>. *' leucopygius
17. *' Temniiiifkii
1 8. Campepliaga morio
*li). '* melanoiis
♦20. ** Snlvadorii (JSharpc)
21. Lalagc leucopvgialis
♦22. " Dominica
Moluccas
X 1
— Java
23. Artamides bicolor
♦24, ** schistaceus (Sliarpe)
X
LIST OF LAND BIRDS OF CELEBES.
429
Celebes.
Sula Is.
Sanghir Is.
Range and Remarks.
DlCRURID^.
25. l^icruriis leticoDS
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X (Wall.)
X
X
X
X var.
X
X
•
X (Wall.)
X
X
X 1 X 1 X till X
♦26. ** axillaris (Salv.). . .
♦27. " pectoralis (Wall.)
McSCICAPIDiE.
28. Cvornis rafisula.
29. ** banvuroas
Java and Borneo
80. Mvialestes helianthea
31. Uypothymis puella.
33. ** Mcnadensis?..
♦33. Monarclia commutata
rBruffflr.) .... J
(Indian ally)
♦34. Monarclia cinerascens
PACHYCKPHALIDiE.
35. Hylocharis sulfurirentra....
♦36. Pachycephala lineolata
(Wall.)
Moluccas
Bourn
♦37. Pachycephala rufescens
♦38. Pachycephala Clio (Wall.).
Laniidje.
♦39. Lanius magnirostris (Merer)
CORVID-K.
40. Cor^'us enca
Bouru
Bouru
Java
Java
♦41. ** nnnectens (Briigg.).
42. ** (Gazzola) typica.. . .
43. Strcptocitta Caledonica
44. " torqunta.
♦45. (Charilonii8)Albertia(Scljl.)
Meliphagid^.
46. Myzomela cbloroptera
NECTARIXIIDili:.
47. Anthreptes Malaccensis
(Celebensis. Shelley)
48. Chalcostethia porpbyolsema
*49. ** anriceps
(Nearest M, san^wi-
noltnta of Aus.)
Siam, Bfulaya
Temate
♦oO. " Sangirensis (Meyer).
51. Aracbnectbra franata
52. Nectarophila Grayi ........
53. ^thopvga flavostriata.
♦54. ** Beccarii (Salv.)
♦55. ** Duyvenbodei (Scbl.).
56. Zosterops intermedia.
57. * ' ntrifrons
Moluccas and K.
Guinea.
(An Oriental genus)
Lombok
58. Dicsum Celebiciim
480
ISLAND LIFE.
ColobML
•59. I>ic»am8tnghiroiiie(S«Iv.)
60. FachygloMii aureoUmlMUa. .
HlRUKDIHIDA
61. Hirandogattiiralis.,
62. ** Jafanica. .
PfX>CBIDJB.
68. Miinia oryaifora. . . .
6i. '* niioria.
65. " Molucca
66. ** branneicept..
•67.
t(
Jiigori.
SruBinDiB.
68. Basilornii Cdebensia. .
69. Acridotherai cineroas.
7<l. Starnia pyrrliogenjrt. -
71. Calomifl neglacta
•7S. '' metaUica....
78. Enodes efythrophrjs. .
74. Scistiroatrum Fagei. . .
ASTAMIDJB.
75. Artamas monachus
76. ** leiuiorhjnchns. . . .
MOTACILLID.K.
77. Conrdalla Gustavi
78. Budytes viridis...
•79. Colobatefl melanope=(Mo-
tac. flulfurco. Bi-iigg.)* • •
PlTTIDA.
80. Fitta Forateni
♦81.
82.
*«3.
•84.
•85.
Sangliirana (Schl.). .
Celebensis
imlliceps (Briigg.) —
cieruleitorqaes (Salv.)
irena (=cra8»irostri!*)
X
X
X
X
X
X
xC&Tejer)
X
X
X
X
x{Bragg.)
X
X
X
X
X
X
Bala la
X
X(WaU.)
Suighlria
X
X
X var.
X
X
PlCID.«.
8f>. MuUeripicus fnlvus
87. Yungipicus Temminckii. . . .
CuCOLIDiK.
88. Khamphococcyx culorhyn-
cbas i
89. Centropus Celcbensiu.
90. ** nffiiiis I
91. '* Javanensis
92. Cuculiis canoras
98. Cacomantes lanceolatus. . . . ;
X
X
X (Wall. )
X
X
X
X
X
X
X
X
Induin Kegion
Indo-Malaya
Jara
JaTa
Molaccfli
(Near M, m^rmii-
jfus, India)
Philippine
Range and Remarka.
Afnlaya
Afolaccai
Af alaj ArcbipeL
Java, Moluccas
China, Fliilipp.
Timor, Temate?
Java
Java, Borneo
Java
LIST OF LAND BIRDS OF CELEBES.
431
Colebca
Sula 18.
Sasgtair Is.
Rango and Remarks.
94. Cncomantcs sepulchrnlis.. .
95. llierococcyx crassisostris..
96. Eudvnamis mclanorhyncha
♦07. '" facialis (Wall.>
♦98. ** orientalis
99. Scvthrops Nuvsehollandis.
CORACIIDA.
100. Coracias Temroinckii
101. Eurystomus orientalis
Meropida.
102. Meropogon Forsteni
103. Merops Philippinus
104. ** oniatus
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X (Wall.)
X
x(Biugg.)
X
X
X
X
X
Moluccas ?
Molaccas, etc.
Asia
Oriental Region
Java, Aastralia
Molaccas
Indo-Malaya
(Allied to Mol. sp.)
Alcedinidje.
10.>. Alcedo Moluccensis
106. •' Asiatica..:
107. Pelargopsismelanorhyncliu
♦108. Ceyx Wallacei (Shai-pe) . .
109, CeycoDsis fallax
110. Ualcvon cliloris
All Archipel.
All Archipel.
111. ** sancta
112. ** Forsteni
113. ** rufa
1 14. Monacbalcyon princeps. .
♦115. ** cyanocephala(BrUgg.)
1 16. Cittura cvanotis.
♦117. " Sanghirensis (Schl.)
BCCEUOTID^.
118. llydrocissa exarata
119. Crunorhinus cassidix
CAPRIMULGIDiE.
1 20. Capriraulgus affinis.
121. ** sp
122. Lyncornis macropterus
Ctpselidje.
123. Dendrochelidon Wallace!..
124. CoUocalia esculenta
1 25. * * faciphnga.
126. Chsetura ffimutea
Mol. to Ara Is.
India, Java
India. Java
PSITTACI.
1 27. C/Ucatiia sulpharea
1 28. Prionitui-us platurus
129. " flavicans
♦130. Platycerciis dorsalis, var.. .
131. Tanygnatbus Mullen
♦132. '** megalorhynchus
Lombok, Flores
N. Guinea?
Moluccas. Anis.n.
Menado (Meyer)
432
ISLAND LIFE.
Celebe&
Sula Is.
Sanghir Is.
Range and Remarks.
*133. Tanygnathns Luzoniensis.
134. Loriculus stigmatus
♦186. ** quadricolor (Wald.)
136. " Sclateri
X
X
?
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X (Meyer)
X
X
X
X
X
X Mever
»
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X var.
X(Briigg.)
X
X
X var.
Sanglii-
rensis.
X var.
Xanthor-
rhoa.
Salv.
X (Salv.)
X
X
X
X
X
Togian I*., Gulf
of Tomini
187. ** exilis
♦188. ** catamene (Schl.)...
139. Trichoglossus ornatus
♦140. " flavoviridis (Wall.)
141. ** Meyeri
♦142. Eos histrio = E. coccinea
COLUMBA.
143, Treron vernans
MalacyJarayPhilip.
144. ** griseicauda
145. FtiloDas formosus
146. ** melanocephalus..
147. ** gularis.
Java, Lombok
♦148. " Fischeri (Brugg.).
149. Carpophaga paulina
♦150. ** pulchella(Wald.)..
151. ** concinna
Togian If!. {Ann.and
Mag. Nat, Hist,
1874.)
Ke Goram
1 52. " rosacea
Gilolo. Timor
♦153. ** pa;cilorrhoa(Briigg.)
154. ** luctuosa
♦155. ** bicolor
N. Guinea. Moluc.
156. ** radiata
157. ** Forsteni
158. Macropygia albicapilla
1 50. ** Macassariensis
♦160. ** Sanghirensis(Salv.)
161. Turacoeiia Menaderusis
♦162. Keiinvardtifiias lieinwardti
1 6.'J. Turtur tiiirina
Moluccas and N.G.
NlnlaviL. IVIoIurons
164. Clialcophaps Stephani
165. *' Indica
1 ()6. I*liloga;nas trisiiginata
1 ()7. ticoijclia striata
New Guinea
Indiaand Archipcl.
Pbina .Tavn Tx^mb
1 68. CaUuuas Nicobarica
Gallina:.
169. Gallus Bankiva
Malacca and New
Guinea
•Tavn Timor
1 70. Coturiiix minima
{ynwofCatinensis)
171. Turnix niHIatiis
♦172. '* Beccnrii (Salv.)...
173. Megapodius Gilberti
1 74. Megaceplialoii tiialleo
LIST OF LAND BIRDS OF CELEBES.
433
Celebca
Sula la.
Sangbir I&
Raogo and Romarka
ACCIPITRES.
] 75. Circus assimilis
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
I X I X X X
X
Australia
1 76. Astiir sriseiceDs
♦177. *' tennirostris (Briigg.)
178. ** rhodognstra.
179. '* trinotata
♦180. Accipiter Sulaensis (Schl.)
181. ** Soloensia.
182. Neopus Malnyensis
183. Spizaetns lanceolatas
184. HaliaBtus leucogaster
185. Spilomis rufipectos
186. Butastur liventer ,
Malacca and New
Guinea
Nepaul, Sum., Java,
Moluccas
Oriental Region
Java. Timor
187. " Indicus.
India. Java
188. IXnliastnr leucostemiis. —
189. Milvusnffinis
MoluccaSfN.Gninea
Australia
1 90. Klanus hypoleacus
191. FemU ptilorhyncha.
(var. Cclebensis)
192. Baza erythrothorax
1 93. Faico severus
? Java, Borneo
(Var, Java, etc.)
All Archipel.
Java, Moluccas
India, Malaya
194. Cerchneis Molaccensis.. . . .
195. PoliosBtas humilis.
STRIOIDiE.
196. Athene punctulata
197 ** ochracea
1 98. ScoDS maeicus
Amboyna, etc. ?
Flores.Madafirascar
199 ** Menadensis
200. Ninox JtiDonicus
China, Japan
MoIacca
*20l. " scutulata
202. Strix Rosenbergi
28
434 ISLAND LIFE. [Past II.
CHAPTER XXI.
ANOMALOUS ISLANDS: NEW ZEALAND.
Position nnd Physical Featares of New Zealand. — Zoological Character of New Zen-
land* — Mammalia. — Wingless Birds Living and Extinct. — Recent Existence of th«
Moa. — Past Changes of New Zealand Deduced from its Wingless Birds. — Birds
and Reptiles of New Zealand. — ConcIu.«ions from the Pecoliarities of the New Zea-
land Fanna.
The fauna of Xew Zealand has been so recently described,
and its bearing on the past history of tlie islands so fully dis-
cussed in njy large work already referred to, that it would not
be necessary to introduce the subject again, were it not that we
now approach it from a somewhat diflferent point of view, and
with some important fresh material, which will enable us to ar-
rive at more definite conclusions as to the nature and origin of
this remarkable fauna and flora. The present work is, besides,
addressed to a wider class of readers than my former volumes,
and it would be manifestly incomplete if all reference to one
of the most remarkable and interesting of insular faunas were
omitted.
The two great islands which mainly constitute Xew Zealand
are together about as large as the kingdom of Italy. They
stretch over thirteen degrees of latitude in the warmer portion
of the south temi)erate zone, tlnn'r extreme points corresponding
to the latitudes of Vienna and Cyprus. Their climate through-
out is mild and efjuable, their vegetation is luxuriant, and des-
erts or uninhabitable regions are as comjdctely unknown as in
our own islands.
The biological structure of these islands has a decidudlv con-
tinental character. Ancient sedimentary rocks, granite, and mod-
ern volcanic formations abound; gold, silver, copper, tin, iron,
and coal are plentiful ; and there are also some considerable de-
Caxr. TTT]
NEW ZEALAND.
435
posits of earl/ or late Tertiary age. Tlie Secondary rocka aloiio
are very scantily developed, and bucIi fragments as exist aro
chiefly of Cretaceous age, often not clcaily separated from the
succeeding Eocene beds.
The position of New Zealand in the great Sonthern Ocean,
about I'lOO miles distant from tho Anstralian continent, is very
isolated. It is surrounded hy a modcratuly deep ocean ; hut the
form of the sea-bottom is peculiar, and nmy help us in the sotn-
tion of some of the anomalies presented by its living produc-
tions. The line of 2<lU fathoms encloses the two islands and ex-
tends their area considerably; but the lOOU-fathom line, which
indicates the land-area that wonld be piodiiced if the sea-liottom
were elevated fiOOO feet, has a very remarkable conformiUioii,
extending in a broad mass wcstwai'd, and then gending out two
great arms, one reaching to beyond Lord Howe's Island, while
the other stretches over Norfolk Island to tho great barrier reef,
thus forming a connecliuii witii Iropicnl Anstmlia and New
436 ISLAND LIFE. [Part II.
Gninea. Temperate Australia, on the other hand, is divided
from New Zealand by an oceanic gulf about 700 miles wide and
between 2000 and 3000 fathoms deep. The 2000-fathom line
embraces all the islands immediately round New Zealand ; and
a submarine plateau at a depth somewhere between one and two
thousand fathoms stretches southward to thfe antarctic conti-
nent. Judging from these indications, we should say that the
most probable ancient connections of New Zealand were with
tropical Australia and New Guinea, and perhaps, at a still more
remote epoch, with the great southern continent by means of
intervening lands and islands ; and we shall find that a land-con-
nection or near approximation in these two directions at remote
periods will serve to explain many of the remarkable anomalies
which these islands present.
Zoological Character of New Zealand, — ^We see, then, that
both geologically and geographically New Zealand has more of
the character of a "continental" than of an "oceanic" island;
yet its zoological characteristics are such as almost to bring it
within the latter category, and it is this which gives it its
anomalous character. It is usually considered to possess no in-
digenous mammalia; it has no snakes, and only one frog; it
possesses (living or quite recently extinct) an extensive group of
birds incapable of flight; and its productions generally are won-
derfully isolated, and seem to bear no predominant or close rela-
tion to those of Australia or any other continent. These are the
characteristics of an oceanic island; and thus we find that the
inferences from its physical structure and those from its forms
of life directly contradict each other. Let us see how far a closer
examination of the latter will enable us to account for this ap-
parent contradiction.
Mammalia of New Zealand, — The only undoubtedly indige-
nous mammalia appear to be two species of bats, one of whicli
{Scotoj)hllu8 tuherculatus) is, according to Mr. Dobson, identical
with an Australian form, while the other {Myf^tachia iuhercu-
latd) forms a very remarkable and isolated genus of Emballonu-
ridffi, a family which extends throughout all the tropical rec^ions
of the globe. The genus Mystacina was formerly considered to
belong to the American Phyllostomidse, but this has been shown
438 ISLAND LIFE. [Part II.
tains of the South Islaud of a small otter-like animal. Dr. Haast
has seen its tracks, resembling those of our European otter, at a
height of 3000 feet above the sea in a region never before trod-
den by man; and the animal itself was seen by two gentlemen
near Lake Heron, about seventy miles due west of Cliristchurch.
It was described as being dark-brown and the size of a large rabbit.
On being struck at with a whip, it uttered a shrill yelping sound
and disappeared in the water.* An animal seen so closely as to
be struck at with a whip could hardly have been mistaken for a
dog — the only otlier animal that it could possibly be supposed
to have been — and a dog would certainly not have "disappeared
in the water." This account, as well as the footsteps, points to
an aquatic animal ; and if it now frequents only the high alpine
lakes and streams, this might explain why it has never yet been
captured. Hochstetter also states that it has a native name —
Waitoteke — a striking evidence of its actual existence ; while a
gentleman wlio lived many years in the district assures me that
it is universally believed in by residents in that paTt of New
Zealand. The actual capture of tliis animal, and the determi-
nation of its characters and affinities, could not fail to aid us
greatly in our speculations as to the nature and origin of the
New Zealand fauna.'
WingUssIiirds^ Living and Extinct, — Ahnost equally valuable
* Ilochstetter's ** New Zealnnd," p. IGl, note.
' The aiiiinnl described by Captain Cook as having been seen at Pickersgill Har-
bor in Dusky Hay (Cook's *' Second Voyage," Vol. I., p. 08) may liave been the same
creatiu'e. lie says, '* A four-footed animal was seen by three or four of our people ; but
as no two gave ihe same description of it, I cannot say what kind it is. All, how-
ever, agreed that it was about the size of a cat, with short legs, and of a mouse-color.
One of the seamen, and he who had the best view of it, said it had a bushy tail, and
was the most like a jackal of any animal he knew." It is suggestive that so far as
the points on which '*all agreed" — the size and the dark color — this descri])tion
would answer well to the animal so recently seen, while the *' short legs " corre-
spond to the ottci-like tracks, and the thick tail of an otter like animal m:iy well have
appeared *' bushy "' when the fur was dry. It has been suggested that it was only
one of the native dogs ; but as none of those who saw it took it for a dog, and the
points on which they all agreed are not dog-like, we can hardly accept this explana-
tion ; while the actual existence of an unknown animal in New Zealand of corre-
sponding size and color is confirmed by this account of a similar animal having been
seen about a century ago.
Chap. XXI.] NEW ZEALAND. 439
with mammalia in affording indications of geographical changes
are the wingless birds for which New 2Sealand is so remarkable.
These consist of four species of Apteryx, called by the natives
" kiwis " — creatures which hardly look like birds, owing to tlie
apparent absence (externally) of tail or wings and the dense cov-
ering of hair-like feathers. They vary in size from that of a
small fowl up to that of a turkey, and have a long slightly
curved bill, somewhat resembling that of the snipe or ibis. Two
species appear to be confined to the South Island and one to the
North Island ; but all are becoming scarce, and they will, no doubt,
gradually become extinct. These birds are generally classed
with the Struthiones, or ostrich tribe, but they form a distinct
family, and in many respects differ greatly from all other known
birds.
But, besides these, a number of other wingless birds, called
"moas," inhabited New Zealand during the period of human
occupation, and have ouly recently become extinct. These were
much larger birds than the kiwis, and some of them were even
larger than the ostrich, a specimen of Dinornis 7naximu8 mount-
ed in the British Museum in its natural attitude being eleven
feet high. They agreed, however, with the living Apteryx in
having four toes, and in the character of the pelvis and some
other parts of the skeleton ; while in their short bill and in some
important structui*al features they resembled the emu of Aus-
tralia and the cassowaries of New Guinea.* No less than eleven
distinct species of these birds have now been discovered ; and
their remains exist in such abundance — in recent fluviatile de-
posits, in old native cooking -places, and even scattered on the
surface of the ground, that complete skeletons of several of
them have been put together, illustrating various periods of
growth from the chick up to the adult bird. Feathers have
also been found attached to portions of the skin, as well as the
stones swallowed by the birds to assist digestion, and eggs, some
containing portions of the embryo bird ; so that everything con-
* Owen, "On the Genus Dinornis," TransactionB of thB Zoological Society j VoL
X., p. 184; Mivart, " On the Axial Skeleton of the Strathionidae,'' Tramactiona of
the Zoological Society , Vol. X., p. 51.
440 ISLAND LIFa [Pakt U.
firms the statements of the Maoris — that their ancestors foand
these birds in abundance on the islands ; that they hnnted them
for food ; and that they finally exterminated them only a short
time before the arrival of Europeans.* Bones of Apteryx are
also fonnd fossil, but apparently of the same species as the liv-
ing birds. How far back in geological time these creatures or
their ancestral types lived in New Zealand we have as yet no
evidence to show. Some specimens have been found under a
considerable depth of fluviatile deposits which may be of Qua-
ternary or even of Pliocene age ; but this evidently affords ns
no approximation to the time required for the origin and devel-
opment of such highly peculiar insular forms.
Past Changes of New Zealand Deduced from its Wingless
Birds,-^lt has been well observed by Captain Ilutton, in his in-
teresting paper already referred to, that the occurrence of such a
number of species of Struthious birds living together in so small
a country as New Zealand is altogether unparalleled elsewhere
on tlie globe. This is even more remarkable when we con-
sider that the species are not equally divided between the two
islands, for remains of no less than ten out of the eleven known
species of Dinornis have been found in a single swamp in the
Soutli Island, where also three of the species of Apteryx oc-
' Tlie recent existence of the mon,and its having been exterminnted by the Maoris,
appears to Ik; at length set at rest by the statement of Mr. John White, a gentleman
who has been collecting materials for a history of the natives for thirty-five years, who
has been initiated by their priests into all the mysteries, and is said to **know more
about the history, habits, and customs of the Maoris than they do themselves." His
information on this subject was obtained fiom old natives long beftne the controversy
on the subject arose. He says that the histories and songs of tho Maoris abound
in allu>ions to the moa, and that they were able to give full accounts of **it8 habits,
food, the season of the year it was killed, its api)earance, strength, and all the numer-
ous ceremonies which were enncted by the natives liefore they began the hunt ; the
mode of hunting, how cut up, how cooked, and what wood was used in the cooking,
with an account of its nest, and how the nest wris made, where it usuallv lived, etc."
Two pages are occupied by these details, but they are only given from memory, and
Mr. White promises a full account from his MSS. Many of the details given coitc-
spond with facts ascertained from the discovery of native cooking-places with moa's
bones ; and it seems quite incredible that such an elaborate and detailed account
should be all invention (see Transactions of the Xew Zealand /«.^/iV«/^r, Vol. Vlll.,
p. 75)).
Chap. XXL] NEW ZEALAND. 441
cur. The New Zealand Struthiones, in fact, very nearly equal in
number those of all the rest of the world, and nowhere else do
more than three species occur in any one continent or island,
while no more than two ever occur in the same district. Thus
there appear to be two closely allied species of ostriches inhab-
iting Africa and Southwestern Asia respectively. South America
has three species of Ehea, each in a separate district. Australia
has an eastern and a western variety of emu, and a cassowary in
the north ; while eight other cassowaries are known from the
islands north of Australia — one from Ceram, two from the Am
Islands, one from Jobie,one from New Britain, and three from
New Guinea — but of these last," one is confined to the northern
and another to the southern part of the island.
This law, of the distribution of allied species in separate areas
— which is found to apply more or less accurately to all classes
of animals — is so entirely opposed to the crowding together of
no less than fifteen species of wingless birds in the small area of
New 2^aland that the idea is at once suggested of great geo-
graphical changes. Captain Ilutton points out that if the isl-
ands from Ceram to New Britain were to become joined togeth-
er, we should have a large number of species of cassowary (per-
haps several more than are yet discovered) in one land area. If,
now, this land were gradually to be submerged, leaving a cen-
tral elevated region, the different species would become crowded
together in this portion, just as the moas and kiwis were in New
Zealand. But we also require, at some remote epoch, a more
or less complete union of the islands now inhabited by the sep-
arate species of cassowaries, in order that the common ancestral
form which afterwards became modified into these species could
have reached the places where they are now found ; and this
gives ns an idea of the complete series of changes through which
New Zealand is believed to have passed in order to bring about
its abnormally dense population of wingless birds. First, we
nmst suppose a land-connection with some country inhabited
by Struthious birds, from which the ancestral forms might be
derived ; secondly, a separation into many considerable islands,
in which the various distinct species might become differen-
tiated ; thirdly, an elevation bringing about the union of these
442 ISLAND LIFE. IT^kt II.
ifelands to onite the distinct species in one area ; and. fourthly, a
6ub&idcnce of a large part of the area, leaving the present islands
with the various species crowded together.
If New Zealand has really gone through such a series of
clianges as here suggested, some proofs of it might perhaps be
obtained in the outlying islands which were once, presumably,
joined with it. And this gives great importance to the state*
ment of the aborigines of the Chatham Islands that the Apteryx
formerly lived there, but was exterminated about 1835. It is
to be hoped that some search will be made here, and also in Xor-
folk Island, in both of which it is not improbable remains of
Apteryx or Dinomis might be discovered.
So far we find nothing to object to in the speculations of
Captain Hutton, with which, on the contrary, we almost wholly
concur; but we cannot follow him when he goes on to suggest
an antarctic continent uniting New Zealand and Australia vrith
South America, and probably also with South Africa, in order
to explain the existing distribution of Struthious birds. Our
best anatomists, as wc have seen, agree that both Dinornis and
Apteryx are more nearly allied to the cassowaries and emus than
to the ostriches and rheas; and we see that the form of the
sea-bottom su^ests a former connection with Nortli Australia
and New Guinea — the very region where these types most
abound, and where in all probability they originated. Tlie sug-
gestion that all the Struthious birds of the world sprang from
a common ancestor at no very remote period, and that their ex-
isting distril)ution is due to direct land communication between
the countries tliey now inhabit, is one utterly opposed to all
sound principles of reasoning in questions of geographical dis-
tribution ; for it depends upon two assumptions, both of which
are at least doubtful, if not certainly false — tlie first, that their
distribution over the globe has never in past ages been very
different from what it is now; and the second, tJiat tlie ances-
tral forms of these birds never liad the power of fliglit. As to the
iirst assumption, we have found in almost every case tliat groups
now scattered over two or more continents formerly lived in
intervening areas of existing land. Thus, the marsupials of
South America and Australia are connected by forms which
Chap. XXL] NEW ZEALAND. 443
lived in North America and Europe; the camels of Asia and
the llamas of the Andes had many extinct common ancestors in
North America ; the lemura of Africa and Asia had their ances-
tors in Europe, as did the trogons of South America, Africa,
and tropical Asia. But, besides this general evidence, we have
direct proof that the Struthious birds had a wider range in past
times than now. Remains of extinct rheas have been found in
Central Brazil, and those of ostriches in North India ; while re-
mains believed to be of Struthious birds are found in the Eo-
cene deposits of England ; and the Cretaceous rocks of North
America have yielded the extraordinary toothed bird Hesper-
ornis, which Professor O. Marsh declares to have been " a car-
nivorous swimming ostrich."
As to the second point, we have the remarkable fact that all
known birds of this group have not only the rudiments of wing-
bones, but also the rudiments of wings; that is, an external
limb bearing rigid quills or largely developed plumes. In the
cassowary these wing-feathers are reduced to long spines like
porcupine-quills, while even in the Apteryx the minute external
wing beare a series of nearly twenty stiflE quill-like feathers.*
These facts render it probable that the Struthious birds do not
owe their imperfect wings to a direct evolution from a reptilian
type, but to a retrograde development from some low form of
winged birds^ analogous to that which has produced the dodo
and the solitaire from the more highly developed pigeon-type.
Professor Marsh has proved that, so far back as the Cretaceous
period, the two great forms of birds — those with a keeled sternum
and fairly developed wings, and those with a convex keelless
sternum and rudimentary wings — already existed side by side;
while in the still earlier Archseopteryx of the Jurassic period
we have a bird with well-developed wings, and therefore prob-
ably with a keeled sternum. We are evidently, therefore, very
far from a knowledge of the earlier stages of bird-life, and our
acquaintance with the various forms that have existed is scanty
in the extreme ; but we may be sure that birds acquired wings
> See iignre in Transactions of the New Zealand Institute^ Vol. 1 1 L, Plate 12 6,
Fig. 2.
444 ISLAND LIFE. [Past II.
and feathers, and some power of flight, before tbev developed
a keeled stemnni, since we see that bats with no such keel fljr
very well. Since, therefore, the Stmthions birds all have per-
fect feathers, and all have mdimentary wings which are ana-
tomically those of tme birds, not the rudimentary forelegs of
reptiles, and since we know that in many higher gronps of birds
— as the pigeons and the rails — ^the wings have become more or
less aborted, and the keel of the sternum greatly reduced in size
by disuse, it seems probable that the very remote ancestors of
the rhea, the cassowary, and the Apteryx were true flying birds,
although not perhaps provided with a keeled sternum, or pos-
sessing very great powers of flight. But, in addition to the pos-
sible ancestral power of flight, we have the undoubted fact that
the rhea and the emu both swim freely, the former having been
seen swimming from island to island off the coast of Patagonia.
This, taken in connection with the wonderful aquatic ostrich
of the Cretaceous period discovered by Professor Mai'sh, opens
up fresh possibilities of migration ; while the immense antiquity
thus given to the group, and their universal distribution in past
time, render all suggestions of special modes of communication
between the parts of the globe in which their scattered remnants
noio happen to exist altogether superfluous and misleading.
The bearing of this argument on our present subject is that,
so far as accounting for the presence of wingless birds in Xew
Zc«aland is concerned, we have nothing whatever to do with any
possible connection by way of a southern continent or antarc-
tic islands with South America and South Africa, because the
nearest allies of its nioas and kiwis arc tlie cassowaries and emus ;
and we have distinct indications of a former land-extension tow-
ards North Australia and Xew (xuinea, which is exactly what we
require for the original entrance of the Struthious type into tlie
New Zealand area.
Whifjal Jilrth and Low^'r Vertehrates of Xew Z^Hiland. — Hav-
ing given a pretty full account of the New Zealand fauna else-
where,* I need only here point out its bearing on the hypothesis
now advanced, of the former land-connection liavinu: been with
1 (i
Gcogrnphicnl Distribution of Animnl.'*," Vol. I., p. 4.'iO.
CiiAP.XXL] NEW ZEALAND. 445
North Australia, New Guinea, and the "Western Pacific islands,
rather than with the temperate regions of Australia.
Of the Australian genera of birds which are found also in
New Zealand, almost every one ranges also into New Guinea
or the Pacific islands, while the few that do not extend beyond
Australia are found in its northern districts. As regards the
peculiar New Zealand genera, all whose affinities can be traced
ai-e allied to birds which belong to the tropical parts of the
Australian Region ; wliile the starling family, to which four of
tlie most remarkable New Zealand birds belong (the genera
Creadion, Heterolocha, and Callseas), is totally wanting in tem-
perate Australia and is comparatively scarce in the entire Aus-
tralian Region, but is abundant in the Oriental Region, with which
New Guinea and the Moluccas are in easy communication. It
is certainly a most suggestive fact that there are more than six-
ty genera of birds peculiar to the Australian continent (with
Tasmania), many of them almost or quite confined to its tem-
perate portions, and that no single one of these should be repre-
sented in temperate New Zealand.* The affinities of the living
and more liighly organized no less than those of the extinct and
wingless birds strikingly accord with the line of communication
indicated by the deep submarine bank connecting these temper-
ate islands with the tropical parts of the Australian Region.
The reptiles, so far as they go, are quite in accordance with
the birds. The lizards belong to three genera — Hinulia and
Mocoa, which have a wide range in the Eastern tropics and the
Pacific and Malayan regions, as well as Australia ; and Naulti-
nus, a genus peculiar to New Zealand, but belonging to a family
(Geckotidae) spread over the whole of the warmer parts of the
world. Australia, on the other hand, has three small but pecul-
iar families, and no less than thirty-six peculiar genera of liz-
ards, many of which are confined to its temperate regions, but
no one of them extends to temperate New Zealand. The ex-
t
* In my "Geographical Distribution of Animals," Vol. I., p. 541, 1 have given two
peculiar Australian genera (^Orthonyx and Tribonjfx) as occurring in New Zealand.
But the former has been found in New Guinea, while the New Zealand bird is con-
sidered to form a distinct genus, Clitonyx ; and the latter inhabits Tasmania, and
was recorded from New Zealand through an error (see /6t5, 1873, p. 427^.
44^ ISLAND LUX. [Par II.
traordinarr Ifzard-like Hatteria punctata of Xew Zealand forms
of itself a distinct order of reptiles, in some respects intermedi-
ate between lizards and crocodiles, and having therefore no af-
finity with any living animaL
The only representative of the Amphibia in New Zealand is
a fiolitarj frog of a peculiar genus (Liopelma Hochiftetterh ; bot
it has no affinity for any of the Australian frogs, which are nu-
merous, and belong to eleven distinct families : while the Lio-
pelma belongs to a Tery different family (BombinatoridseK con-
fined to Europe and temperate South America.
Of the fresh-water fishes we need onlv sav here that none
Ijelong to peculiar Australian types, but are relateil to those of
temperate South America or of Asia.
T^e Invertebrate classes are comparatively little known, and
their modes of dispersal are so varied and exceptional that the
facts presented by their distribution can add little weight to
those already adduced. We will therefore now proceed to the
conclusions wliich can fairly be drawn from the general facts of
New Zealand mitural historv alreadv known to us.
Jjeductiormfroia the Peculiarities of the Xc^c Zt aland Fauna.
— The total absence Tor extreme scarcitv) of mammals in New
Ze'dland obliires us to place its union with North Australia and
Ncv/ Guinea at a very remote epoch. AVe must either go back
to a time when Australia itself liad not vet received the ances-
tral forms of its present marsupials and niouotrenies. (»r we must
suppose that the portion of Australia with which New Zealand
was coimected was then itself isolated from the mainland, and
was thus without a mammalian population. We shall sec in
our next chapter that there are certain facts in the distribution
of plants, no less than in the geoloo^ieal structure of the country,
which favor the latter view. iJut we must on any supposition
plaee the union very far back, to account for the total want of
identity between the winged birds of New Zealand and those
]>eculiar to Australia, and a similar want of accordance in the
lizards, the fresh-water lishes, an<l the more important insect-
groups of the two countries. From what we know of the lonir
ge(dogical duration of the generic types of these groups, we
must certainly go back to the earlier portion of the Tertiary
Chap. XXL] NEW ZEALAND. 447
period at least, in order that there should be such a complete
disseverance as exists between the characteristic animals of the
two countries ; and we must further suppose that, since their
separation, there has been no subsequent union or sufiScientlj
near approach to allow of any important intermigration, even
of winged birds, between them. It seems probable, therefore,
that the Bampton shoal, west of New Caledonia, and Lord Howe's
Island farther south, formed the western limits of that exten-
sive land in which the great wingless birds and other isolated
members of the New Zealand fauna were developed. Whether
this early land extended eastward to the Chatham Islands and
southward to the Macquaries, we have no means of ascertaining ;
but as the intervening sea appears to be not more than about
1500 fathoms deep, it is quite possible that such an amount of
subsidence may have occurred. It is possible, too, that there
may have been an extension northward to the Kcrmadec Islands,
and even farther to the Tonga and Fiji Islands, though this is
hardly probable, or we should find more community between
their productions and those of New Zealand.
A southern extension towards the antarctic continent at a
somewhat later period seems more probable, as affording an easy
passage for the numerous species of South American and ant-
arctic plants, and also for the identical and closely allied fresh-
water fishes of these countries.
The subsequent breaking -up of this extensive land into a
number of separate islands in which the distinct species of moa
and kiwi were developed, their union at a later period, and the
final submergence of all but the existing islands, are pure hy-
potheses, which seem necessary to explain the occurrence of so
many species of these birds in a small area, but of which we have
no independent proof. There are, however, some other facts
which would be explained by it, as the presence of three peculiar
but alh'cd genera of starlings, the three species of parrots of the
genus Nestor, and the six distinct rails of the genus Ocydromus,
as well as the numerous species in some of the peculiar New
Zealand genera of plants, which seem less likely to have been
developed in a single area than when isolated, and thus pre-
served from the counteracting influence of intercrossing.
448 ISL^VND LIFE. [Part II.
In the present state of onr knowledge, those seem all the con-
clusions we can arrive at from a study of the New Zealand fauna ;
but as we fortunately possess a very full and accui*ate knowledge
of the flora of New Zealand, as well as of that of Australia and
the south temperate lands generally, it will be well to see liow
far these conclusions are supported by the facts of plant-distri-
bution, and what further indications they aflford us of the early
history of these most interesting countries. This inquiry is of
sufficient importance to occupy a separate chapter.
Chap.XXIL] the flora OF NEW ZEALAND. 449
CHAPTER XXII.
THE FLORA OF NEW ZEALAND : ITS AFFINITIES AND PROBABLE
ORIGIN.
lielations of the New Zealund Flora to that of Australia. — General Features of the
Australian Flora. — The Floras of Southeastern and Southwestern Australia. — Geo-
logical Explanation of the Differences of these two Floras. — The Origin of the Aus-
tralian Element in the New Zealand Flora. — Tropical Character of the New Zea-
land Flora Explained. — Species Common to New Zealand and Austrolia mostly
Temperate Forms. — Why Easily Dispersed Plants have often Restricted Ranges. —
Summary and Conclusion on the New Zealand Flora.
Although plants have means of dispersal far exceeding those
possessed by animals, yet as a matter of fact comparatively few
species are carried for very great distances, and the flora of a
country taken as a whole usually affords trustworthy indications
of its past history. Plants, too, are more numerous in species
than the higher animals, and are almost always better known ;
their affinities have been more systematically studied ; and it
may be safely affirmed that no explanation of the origin of the
fauna of a country can be sound which does not also explain,
or at least harmonize with, the distribution and relations of its
flora.
The relations of the flora of New Zealand to that of Australia
have long formed an insoluble enigma for botanists. Sir Joseph
Hooker, in his most instructive and masterly essay on the flora
of Australia, says, " Under whatever aspect I regard the flora
of Australia and of New Zealand, I find all attempts to theorize
on the possible causes of their community of feature frustrated
by anomalies in distribution such as I believe no two other simi-
larly situated countries in the globe present. Everywhere else
I recognize a parallelism or harmony in the main common feat-
ures of contiguous floras, which conveys the impression of their
generic affinity, at least, being affected by migration from centres
29
450 ISLAND LIFE. [Paiit IL
of dispersion in one of tliem, or in some adjacent country. In
this case it is widely different. Kcgarding the question from
the Australian point of view, it is impossible, in the present state
of science, to reconcile the fact of Acacia, Eucalyptus, Casuarina,
Callitris, etc., being absent in New Zealand with any theory of
transoceanic migration that may be adopted to explain the pres-
ence of other Australian plants in New Zealand ; and it is very
diflScult to conceive of a time or of conditions that could ex-
plain these anomalies, except by going back to epochs when the
prevalent botanical as well as geographical features of each were
widely different from what they are now. On the other hand,
if I regard the question from the New Zealand point of view, I
find such broad features of resemblance, and so many connect-
ing-links that afford irresistible evidence of a close botanical
connection, that I cannot abandon the conviction that these great
differences will present the least difficulties to whatever theory
may explain the whole case." I will now state, as briefly as pos-
sible, what are the facts above referred to as being of so anoma-
lous a character, and there is little difficulty in doing so, as we
liave them fully set forth, with admirable clearness, in the essay
above alluded to, and in the same writer's " Introduction to the
Flora of New Zealand," only requiring some slight modifica-
tions, owing to the later discoveries which are given in the
" Handbook of the New Zealand Flora."
Confining ourselves always to flowering 2>lants, we find that
tlie flora of New Zealand is a very poor one, considering the
extent of surface, and the favorable conditions of soil and cli-
mate. It consists of l)o5 species, our own islands possessing
about 15(M); but a very lari^e projmrtion of these are peculiar,
there being no less than G77 endemic species and 82 endemic
genera.
Out of the 2oS species not peculiar to New Zealand, no less
than 222 are Australian, but a considerable number of these are
also antarctic, South American, or European; so that there are
only about 100 species absolutely confined to 2sew Zealand and
Australia; and, what is important as indicating a somewhat re-
cent immigration, only six (►f these belong to genera which are
peculiar to the two countries, and hardly any to the larger and
Chap.XXIL] the flora OP KEW ZEALAND. 451
more important Australian genera. Many, too, are rare species
in both countries, and are often alpines.
Far more important are the relations of the genera and fam-
ilies of the two countries. All the natural orders of New Zea-
land are found in Australia except three — Coriarice, a widely
scattered group found in South Europe, the Himalayas, and the
Andes ; Escallonieie, a widely distributed group ; and Cliloran-
thacejB, found in tropical Asia, Japan, Polynesia, and South
America. Out of a total of 303 New Zealand genera, no less
than 251 are Austnilian, and 60 of these are almost peculiar to
the two countries, only 32, however, being absolutely confined
to them. In the three large orders Compositie, Orchidese, and
GraminecB, the genera are almost identical in the two countries,
while the species — in the two former especially — are mostly dis-
tinct.
Here, then, wc have apparently a wonderful resemblance be-
tween the New Zealand flora and that of Australia, indicated by
more than two thirds of the non-peculiar species, and more than
nine tenths of the non-peculiar genera (255) being Australian.
But now let us look at the other side of the question.
There are in Australia seven great genera of plants, each con-
taining more than 100 species, all widely spread over the coun-
try, and all highly characteristic Australian forms — Acacia, Eu-
calyptus, ^Melaleuca, Leucopogon, Stylidiuu), Grevillea, and Ila-
kea. These arc entirely absent from New Zealand, except one
species of Leucopogon, a genus which also has representatives
in the Malayan and Pacific islands. Sixteen more Australian
genera have over fifty species each, and of these eight are totally
absent from New Zealand, five are represented by one or two
si^jcies, and only two are fairly represented ; but these two —
Drosera and Ilclichrysum — are very wide-spread genera, and
miglit have reached New Zealand from other countries than
Australia.
But this by no means exhausts the diflferences between New
Zealand and Australia. No less than seven important Austra-
lian natural orders — Dilleniaceae, Buettneriaceoe, Polygaleae,
Tremandrece, Casuarineae, IlaemodoraceeB, and Xyridese — are en-
tirely wanting in New Zealand ; and several others which are
452 ISLAND LIFE. [Part II.
excessively abundant and highly characteristic of the former
country are very poorly represented in the latter. Thus, Legu-
ininossB are extremely abundant in Australia, where there are
over 1000 species belonging to about 100 genera, many of them
altogether peculiar to the country; yet in New Zealand this
great order is most scantily represented, there being only five
genera and thirteen species; and only two of these genera,
Swainsonia and Clianthus, are Australian ; and as the latter con-
sists of but two species, it may as well have passed from New
Zealand to Australia as the other way, or more probably from
some third country to them both. Goodeniaceee, with twenty
genera and 230 species Australian, has but two species in New
Zealand, and one of these is a salt-marsh plant found also in
Tasmania and in Chili ; and four other large Australian orders
— Rhamneae, Myoporinece, Proteacese, and Santalacese — have
very few representatives in New Zealand.
We find, then, that the great fact we have to explain and ac-
count for is the undoubted affinity of the New Zealand flora
to that of Australia, but an affinity almost exclusively confined
to the least predominant and least peculiar portion of that flora,
leaving the most predominant, most characteristic, and most
widely distributed portion absolutely unrepresented. We must,
however, be careful not to exaggerate the amount of affinity
with Australia, apparently implied by the fact that nearly six
sevenths of the New Zealand genera are also Australian, for, as
we have already stated, a very large number of these are Euro-
pean, antarctic. South American, or Polynesian genera, whose
presence in the two contiguous areas only indicates a common
origin. About one eighth only are absolutely confined to Aus-
tralia and New Zealand (thirty-two genera), and even of these
several are better represented in New Zealand than in Austra-
lia, and may therefore have passed from the former to the latter.
No less than 174 of the New Zealand genera are temperate South
American, many being also antarctic or European ; while oth-
ers, again, are especially tropical or Polynesian ; yet undoubted-
ly a larger proportion of the natural orders and genera are
common to Australia than to any other country, so that we may
say that the basis of the flora is Australian with a laige inter-
Chap.XXIL] the flora OF NEW ZEALAND. 453
mixture of northern and southern temperate forms and others
which have remote world-wide affinities.
General Features of the Australian Flora ^ and its Probable
Origin. — Before proceeding to point out how the peculiarities
of the New Zealand flora may be best accounted for, it is neces-
sary to consider briefly what are the main peculiarities of Aus-
tralian vegetation, from which so important a part of that of
New Zealand has evidently been derived.
The actual Australian flom consists of two great divisions — a
temperate and a tropical, tlie temperate being again divisible
into an eastern and a western portion. Everything that is char-
acteristic of the Australian flora belongs to the temperate divi-
sion (though these often overspread the whole continent), in
which are found almost all the remarkable Australian types of
vegetation and the numerous genera peculiar to this part of the
world. Contrary to what occurs in most other countries, the
tropical is far less rich in species and genera than the temperate
region, and, w^hat is still more remarkable, it contains compara-
tively few peculiar species and very few peculiar genera. Al-
though the area of tropical Australia is about equal to that of
the temperate portions, and it has now been pretty well explored
botanically, it has less than half as many species.* Nearly 500
of its species are identical with Indian or Malayan plants, or are
' Sir Joseph Hooker informs me tlint the number of tropical Australian phints dis-
covered within the lost twenty years is very great, and that the statement as above
made may have to be modified. Looking, however, at the enormous disproportion
of the figures given in the ** Introductory Essay " in 1859 (2200 tropical to 6800 tem-
perate species), it seems hardly possible that a great difference should not still exist,
at all events as regards species. Sir Joseph Hooker also doubts the generally greater
richness of tropical over temperate floras which I have taken as almost an axiom.
He snys, "Taking similar areas to Australia in tlie Western World — e.g. tropical
Africa north of 20^ as against temperate Africa and Europe up to 47° — I suspect
tliat the latter would present more genera and species than the former." This, how-
ever, appears to me to be hardly a case in point, because Europe is a distinct conti-
nent from Africa, and has had a very different past history. A closer parallel may per-
haps be found in equal areas of Brazil and south temperate America, or of Mexico
and the Southern United States, in both of which cases I suppose there cm be little
doubt that the tropical areas are fur the richest. Temperate South Africa is, no
doubt, always quoted as richer than an equal area of troftical Africa, or perhaps than
any part of the world of equal extent, but this is admitted to be an exceptional case.
454 ISLAND LIFE. [Pjurr IL
very close representatives of them ; while there are more than
200 Indian genera confined, for the most part, to the tropical
portion of Australia. Tlie remainder of the tropical flora con-
sists of certain species and genera of temperate Australia which
range over the whole continent, but these form a very small
portion of the peculiarly Australian genera.
These remarkable facts clearly point to one conclusion — that
the flora of tropical Australia is, comparatively, recent and de-
rivative. If we imagine the greater part of North Australia to
have been submerged beneath the ocean, from which it rose in
the middle or latter part of the Tertiary period, oflfering an ex-
tensive area ready to be covered by such suitable forms of vege-
tation as could first reach it, something like the present condi-
tion of things would inevitably arise. From the north wide-
spread Indian and Malay plants would quickly enter ; while from
the south the most dominant forms of temperate Australia, an«l
such as were best adapted to the tropical climate and arid soil,
would intermingle with them. Even if numerous islands had
occupied the area of Northern Australia for long periods an-
terior to the final elevation, very much the same state of things
would result.
The existence in North and Northeast Australia of enormous
areas covered with Cretaceous and other Secondary deposits, as
well as extensive Tertiary formations, lends supjuu't to the view
that (luring very long epochs temperate Australia was cut off
from all close connection with the tropical and northern lands
by a wide extent of sea ; and this isolation is exactly what was
required in order to bring about the wonderful amount of spe-
cialization and the high develoj)!nent manifested by tlie typical
Australian llora. Before proceeding further, however, let us
examine this fiora itself, so far as regards its component parts
and ja'obable past history.
The Fhiran of Sontfu'aHtfm and jSouf/nV(\^tern Avsfralia, —
The pcculiariti(;s presented by the southeastern and southwest-
ern subdivisions of the llora of temperate Australia are most in-
teresting aiul suggestive, and are, perhaps, unparalleled in any
other ])art of the world. Southwest Australia is far less exten-
sive than the southeastern division — less varied in soil and eli-
Chap.XXIL] the flora OF NEW ZEALAND. 455
mate, with do lofty mountains, and much sandy dessrt ; yet,
strange to say, it contains an equally rich flora and a far greater
proportion of peculiar species and genera of plants. As Sir
Joseph Hooker remarks, "What differences there are in condi-
tions would, judging from analogy with other countries, favor
the idea that Southeastern Australia, from its far greater area,
many large rivers, extensive tracts of mountainous country and
humid forests, would present much the most extensive flora, of
which only the dryer types could extend into Southwestern Aus-
tralia. But such is not the case ; for though the far greater area
is much the best explored, presents more varied conditions, and
is tenanted by a larger number of natural orders and genera,
these contain fewer species by several hundreds.'"
The fewer genera of Southwestern Australia are due almost
wholly to the absence of the numerous European, antarctic, and
South American types found in the southeastern region ; while
in purely Australian types it is far the richer, for, while it con-
tains most of those found in the east, it has a large number alto-
gether peculiar to it; and Sir Joseph Hooker states that "there
are about 180 genera, out of 600, in Southwestern Australia
that are either not found at all in Southeastern, or that are rep-
resented there by a very few species only, and these 180 genera
include nearly 1100 species."
Geological Kcplunation of the Differences of these Two Floras.
— These facts again clearly point to the conclusion that South-
western Australia is the remnant of the more extensive and
more isolated portion of the continent in which the peculiar
Australian flora was principally developed. The existence there
of a very large area of granite — 800 miles in length by nearly
500 in maximum width — indicates such an extension ; for this
granitic mass was certainly once buried under piles of stratified
' Sir Joseph Hooker thinks thnt later discoveries in the Austmlinn Alps and other
parts of East and South Aastralia may have greatly modified, or perhaps reversed, the
at)ove estimate. But even if this should be the case, the small area of Southwest Aus-
tralia will still be, proportionally, far the richer of the two. It is much to be desired
that the enormous mass of facts contained in Mr. Benthani*s ** Flora Australiensis "
should be tabulated and compared by some competent botanist, so as to exhibit the
various relations of its wonderful vegetation in the same manner as was done by Sir
Joseph Hooker with the materials available twenfy-one years ago.
I
456 ISLAND LIFE. [Part II.
rock, since dennded, and then formed the nucleus of the old
Western Australian continent. If we take the 1000-fathora line
around the southern part of Australia to represent the probable
extension of this old land, we shall see that it would give a wide
additional area south of the Great Australian Bight, and form a
continent which, even if the greater part of tropical Australia
were submerged, would be suflScient for the development of a
peculiar and abundant flora. We must also remember that an
elevation of 6000 feet, added to the vast amount which has been
taken away by denudation, would change the whole country, in-
cluding what are now the deserts of the interior, into a moun-
tainous and well- watered region.
But, while this rich and peculiar flora was in process of forma-
tion, the eastern portion of the continent must either have been
widely separated from the western, or had perhaps not yet risen
from the ocean. The whole of this part of the country consists
of Palaeozoic and Secondary formations, with granite and meta-
morphic rocks — the Secondary deposits being largely developed
on both sides of the central range, extending the whole lengtli
of the continent from Tasmania to Cape York, and constituting
the greater part of the plateau of the Blue Mountains and other
lofty ranges. I)uring some portion of the Secondary period,
therefore, this side of Australia must have been almost wholly
submerged beneath the ocean ; and if we suppose that during
this time the western part of the continent was at nearly its
maximum extent and elevation, we shall have a sufficient ex-
planation of the great difference between tlie flora of Western
and Eastern Australia, since the latter would onlv have been
able to receive immigrants from the former at a later period,
and in a more or less fragmentary manner.
If we examine the geological map of Australia (given in Stan-
ford's "^ Compendium of Geography and Travel," volume " Aus-
tralasia"), we shall see good reason to conclude that the eastern
and the western divisions of the country first existed as separate
islands, and only became united at a comparatively recent epoch.
This is indicated by an enormous stretch of Cretaceous and Ter-
tiary formations extending from the Gulf of Carpentaria com-
pletely across the continent to the mouth of the Murray River.
Chap. XXII.] THE FLORA OF NEW ZEALAND. 457
During the Cretaceous period, therefore, and probably through-
out a considerable portion of the Tertiary epoch,* there must
have been a wide arm of the sea occupying this area, dividing
the great mass of land on the west — the true seat and origin of
the typical Australian flora — from a long but narrow belt of land
on the east, indicated by the continuous mass of Secondary and
Palfieozoic formations already referred to, which extend uninter-
ruptedly from Tasmania to Cape York. Whether this formed
one continuous land, or was broken up into islands, cannot be
positively determined ; but the fact that no marine Tertiary beds
occur in the whole of this area renders it probable that it was
almost, if not quite, continuous, and that it not improbably ex-
tended across to what is now New Guinea. At this epoch, then
(as shown in the accompanying map), Australia would consist of
a very large and fertile western island, almost or quite extra-
tropical, and extending from the Silurian rocks of the Flinders
range in South Australia to about 150 miles west of the present
west coast, and southward to about 350 miles south of the
Great Australian Bight. To the east of this, at a distance of
from 250 to 400 miles, extended in a north and south direction
a long but comparatively narrow island, stretching from far
south of Tasmania to New Guinea; while the crystalline and
Secondary formations of central North Australia probably in-
dicate the existence of one or more large islands in that direc-
tion.
The eastern and the western islands — with which we are now
cliiefly concerned — would then differ considerably in their vege-
tation and animal life. The western and more ancient land al-
ready possessed, in its main features, the peculiar Australian
flora, and also the ancestral forms of its strange marsupial fauna,
both of which it had probably received at some earlier epoch by
* From nn examination of the fossil coraU of the Southwest of Victona, Professor
P. M. Duncan concludes ** that at the time of the formation of these deposits the
central area of Australia was occupied by sea, having open water to the north, with
reefs in the neighborhood of Java." The age of these fossils is not known, but as
almost all are extinct species, and some are almost identical with European Pliocene
and Miocene species, they are supposed to belong to a corresponding period (Journal
of the Geological Society , 1870).
458
ISLAND LIFE.
P'ABTtl.
a temporary union with the Asiatic continent over wliat is no»'
the Jara Sea. Eastern Australia, on the other bund, posBeBsed
only tlie riicliincnts of its existing mixed flora, derived fi-om
three distinct sources. Some important fragments of the typi-
cal Anstralinn vegetation liad reached it across tlie marine strait,
!ind had spread widely, owing to tlie soil, climate, and general
conditions being exactly suited to it ; from the north nml north-
cast ft tropical vegetation of Polynesian type had occnpied suit-
nble areas in the north; ■Kh'\]a the extension southward of the
Tasmnninn Pcninsnln, accompanied, probably, as now, with lofty
mountains, favored the imTnigration of south temperate fornifi
CuAP. XXII.] THE FLORA OF NEW ZEALAND. 459
from whatever antarctic lands or islands then existed. The
marsupial fauna had not yet reached this eastern land, which
was, however, occupied in the north by some ancestral Struthi-
ous birds, which had entered it by way of New Guinea through
some very ancient continental extension, and of which the emu,
the cassowaries, the extinct Dromornis of Queensland, and the
moas and kiwis of New Zealand are the modified descendants.
The Origin of the Amtralmn Element in the New Zealand
Flora. — We have now brought down the history of Australia,
as deduced from its geological structure and the strongly mark-
ed features of its flora, to the period when New Zealand was
first brought into close connection with it by means of a great
northwestern extension of that country, which, as already ex-
plained in our last chapter, is so clearly indicated by the form
of the sea-bottom (see map, p. 435). The condition of New
Zealand previous to this event is very obscure. That it had
long existed as a more or less extensive land is indicated by its
ancient sedimentary rocks; while the very small areas occupied
by Jurassic and Cretaceous deposits imply that nmch of the
present land was then also above the sea-level. The country
had probably at that time a scanty vegetation of mixed antarctic
and Polynesian origin ;* but now, for the first time, it would be
open to the free immigration of such Australian types as were
suitable to its climate, and which had already reached the tropical
and suhtrojncal 2>ortion8 of the eastern Australian island. It is
' In Dr. Hector's address ns President of the Wellington Philosophicnl Society,
in 1 872, he refers to the fluvintile deposits of enri y Tertiary or Cretaceous age as
containing valuable deposits of coal, and adds, *'In the associated sandstones and
shales the flora of the period has been in many cases well preserved, and shows that
at a period anterior to the deposit of the marine stratum the New Zealand area was
clothed with a mixed vegetation of dicotyledonous leaves and ferns that in general
character represent those which now constitute the flora of the country. It would
appear from the recent sun-eys of Dr. Haast that the large saurian reptiles in the
Amuri and Waipara beds, the collections of which have been added to largely during
the past year by the exertions of Mr. Henry Travers, lived during the formation of
these coal-seams, and coeval with them was a species of the kauri-tree, the leaves of
which ha^c been found imbedded with the reptilian bones." He goes on to suggest
that '^ even at this remote period, New Zealand formed part of an area that possess-
ed an insular flora, the peculiar characters of which have been presented to the pres-
ent time." — Transactions of the New Zealand Institute,\o\. V., p. 423.
460 ISLAND LIFE. ZFabt II.
here that we obtain tlic clew to those strange anomalies and con-
tradictions presented by the Xew Zealand flora in its relation to
Australia, which have been so clearly set forth by Sir Joseph
Hooker, and which have so puzzled botanists to account for. Bnt
these apparent anomalies cease to present any difficulty when we
see that the Australian plants in Xew Zealand wei'e acquired, not
directly, but, as it were, at second-hand, by union with an island
which itself had as yet only received a portion of the flora. And
then further difficulties were placed in the way of New Zealand
receiving such an adequate representation of that portion of the
flora which had reached East Australia as its qjimate and posi-
tion entitled it to, by the fact of the union being, not with the
temperate, but with the tropical and subtropical portions of that
island, so that only those groups could be acquired which were
less exclusively temperate and had already established them-
selves in tl«3 warmer portion of their new home.
It is therefore no matter of surprise, but oxactly what wo
should expect, that the great mass of pre-eminently temperate
Australian genera should be absent from Xew Zealand, includ-
ing the whole of such important families as Dilleniaceie, Ti"e-
mandrcie, Buettneriaceoe, Polygalew, Casuarineoe, and Iltemodo-
racca^ ; while others, Ruch as Kutacca*, Stackhonsiea*, Rliamneie,
Myrtacea*, Proteacea*, and Santalacea^ arc represented by only
a few species. Thus, too, we can explain the absence of all the
peculiar Australian Leguminosa> ; for these were still mainly
coniincd to tlie great wt'stern island, along with peculiar Acacias
and Kucalypti, which at a later period spread over the whole
continent. It is equally accordant with the view we are main-
taining tliat among tlio groups whicli Sir Josepli Hooker enu-
merates as ** keeping up the features of extratropical Australia in
its tropical quarter,'' j-cveral should liave readied New Zealand,
such as Drosera, some Tittosporea^ and ^lyoporinea*, with a few
Proteaecas Loganiacea\ and Kestiacca*; for most of these are
not only found in tropical Australia, but also in the Malayan and
Pacific islands.
Trojtiodl ( 'Iniracfrr of the New Zeal and Flora KrplalnaL — In
this oriirin of the New Zealand fauna bv a northwestern route
from Northeastern Australia, we find also an explanation of the
Chap.XXIL] the flora OF NEW ZEALAND. 461
remarkable number of tropical groups of plants found there ;
for though, as Sir Joseph Hooker has shown, a moist and uni-
form climate favors the extension of tropical forms in the tem-
perate zone, yet some means must be afforded them for reaching
a temperate island. On carefully going through the "Hand-
book," and comparing its indications with those of Bentham's
"Flora Australiensis," I find that there are in New 2fealand
thirty-eight thoroughly tropical genera, thii*ty-three of which are
found in Australia — mostly in the tropical portion of it, though
a few are temperate, and these may have reached it through New
Zealand.* To these we must add thirty-two more genem, which,
though chiefly developed in* temperate Australia, extend into the
tropical or subtropical portion of it, and may well have reached
New Zealand by the same route.
* The fullowing are the tropicnl genera common to New Zealand aitd Australia :
1. Melicofte, Queensland, Pacific islands.
2. Kugenia. Tropical Australia, Asia, and America.
3. Passijlora, Queensland, tropics of Old World, and America.
4. Myrsine, Tropical and temperate Australia, tropical and subtropical regions.
5. Sapota. Australia, Norfolk Islands, tropics.
6. Cuathodes. Australia and Pacific islands.
7. Jrarsousia. Tropical Australia and Asia.
8. (jfemoatoma. Queensland, Polynesia, Asia.
0. Mitrasacme. Tropical and temf>erate Australia, India.
10. IffOMfea. Tropical Australia, tropics.
11. ifazus. Temperate Australia, India, China.
12. Vitex. Tropical Australia, tropical and subtropical.
18. Pisonia, Tropical Australia, tropical and subtropical.
14. A/lernanthera, Tropical Australia, India, and iSouth America.
15. Tretranthera, Tropical Australia, tropics.
16. Santalum. IVopical and subtropical Australia, Pacific, Malay Islands.
1 7. Carumhium. Tropical and subtropical Australia, Pacific ishmds.
18. Etatosteinma. Subtropical Australia, Asia, Pacific islands.
19. Peperotnia. Tropical and subtropical Australia, tropics.
20. Piper. Tropical and subtropical Austndia, tropics.
21. Dacrydium. Tasmania, Malay, and Pacific islands.
22. Uammara. Tropical Australia, Malay, and Pacific islands.
23. iJendrohium. Tropical Australia, Eastern tropics.
24. BoUtophyUuiii. Tropical and subtropical Australia, tropics.
2.1. Sarcochilus. Tropical and subtropical Australia, Fiji, and Malay Islands.
26. Freycinetia. Tropical Australia, tropical Asia.
27. Cordyline. Tropical Australia, Pacific islands.
28. Dianella, Australia, India, Madagascar, Pacific islands.
20. Cyperux. Australia, tropical regions mainly.
80. Fimhristylis. Tropical Australia, tropical regions.
81. Paspalwn. Tropical and subtropical grasses.
32. Itachne. Tropical and subtropical grasses.
33. Sporobohig, 'tropical and subtropit^ grasses.
462 ISLAND LIFE. [Part II.
On the other hand, wo find but few New Zealand genera cer-
tainly derived from Australia which are especially temperate,
and it may be as well to give a list of such as do occur, with a
few remarks. They are sixteen in number, as follows :
1 . Pennnntia (I sp.). This genus has n species in Norfolk Island, indicating perhaps
its former extension to the northwest.
2. Pomaderris (3 sp.). Two species are common to temperate Anstraliu and Neur
Zealand, indicating recent transoceanic migration.
3. Qnintinia (2 sp.). Tins genus has winged seeds, facilitating migration.
4. Olearia (20 sp.). Seeds with pnppus.
5. Craspcdia (2 sp.). Seeds with pappus. Alpine; identical with Australiun spe-
cies, and therefore of comparatively recent introduction.
C. Celmisia (25 sp.). Seeds with pappus. Ohly three Australian species, two of
wliich are identical with New Zealand forms ; jn-obably, therefore, derived fruni
New Zealand.
7. Ozoihamnus (5 sp.). Seeds with pappus.
8. Epacris (4 sp. ). Minute seeds. Some species arc subtropical, and they are uU
found in the northern (warmer) island of New Zeabmd.
0. Archeria (2 sp.). Minute seeds. U'ajjmania and New Zealand only.
10. Logania (3 sp.). Small seeds. Al])ine phmts.
11. Hedycarya (1 sp.).
12. Chiioglottis (I sp.). Minute seeds. In Auckland Islands. Alpine in Austmlla.
13. Pra.so]>hylliim (1 sp.). Minute seeds. Identical with Australian species.
14. Orihoceras (I sp.). Minute seeds. Close to an Australian species.
\Tt. Alepynim (I sp.). Al[)ine, moss-like. An antarctic type.
IG. iJichelachne (3 sp.). Identical with Australian species. An awned grass.
We tlius see that there are special features in most of these
])l:ints that would facilitate transmission across the sea between
temperate Australia and New Zealand, or to both from some
antarctic ishmd ; and the fact that in several of them the species
are absolutely identical shows that such transmission has oc-
curred in geologically recent times.
/Sjk'cics Cot/itnofi to ^\w Zt'cdand and Australia mipstly Tetn-
pevate Junins. — Let us now take the species which are common
to Xew Zealand and Australia, but found nowhere else, and
which must therefore have passed from one country to the other
at a more recent period than the mass of genera with which we
have hitherto been dealing. These are ninety-six in number, and
they present a striking contrast to the similarly restricted genera
in being wholly temperate in character, the entire list i)rescnting
only a single species which is confined to subtropical East Aus-
Chap.XXIL] the flora OF NEW ZEALAND. 463
tralia — a grass {Apera arundinacea) only found in a few locali-
ties on tlie New Zealand coast.
Now it is clear that the larger portion, if not the whole, of
these plants must have reached New Zealand from Australia (or
in few cases Australia from New Zealand) by transmission across
the sea, because we know there has been no land-connection dur-
ing the Tertiary period, as proved by the absence of all the Aus-
tralian mammalia and almost all the most characteristic Austra-
lian birds, insects, and plants. The form of the sea-bed shows
that the distance could not have been less than GOO miles, even
during the greatest extension of Southern New Zealand and
Tasmania ; and we have no reason to suppose it to have been
less, because in other cases an equally abundant flora of identical
species has reached islands at a still greater distance — notably
in the case of the Azores and Bermuda. The character of the
plants is also just what we should expect ; for about two thirds
of them belong to genera of world-wide range in the temperate
zones, such as Eanunculus, Drosera, Epilobium, Gna])halium,
Senecio, Convolvulus, Atriplex, Luzula, and many sedges and
grasses whose exceptionally wide distribution shows that they
possess exceptional powers of dispersal and vigor of constitu-
tion, enabling them not only to reach distant countries, but also
to establish themselves there. Another set of plants belong to
especially antarctic or south temperate groups, such as Coloban-
thus, Acaena, Gaultheria, Pernettya, and Muhlenbeckia, and
these may in some cases have reached both Australia and New
Zealand from some now submerged antarctic island. Again,
about one fourth of the whole are alpine plants, and these pos-
sess two advantages as colonizers. Tlieir lofty stations place
them in the best position to have their seeds carried away by
winds ; and they would in this case reach a country which, hav-
ing derived the earlier portion of its flora from the side of the
tropics, would be likely to have its higher mountains and favor-
able alpine stations to a great extent unoccupied, or occupied by
plants unable to compete with specially adapted alpine groups.
Fully one third of the exclusively Australo-New Zealand spe-
cies belong to the two great ordere of the sedges and the grasses ;
and there can be no doubt that these have great facilities for
464 ISLAND LIFE. [Part XL
dispersion in a variety of ways. Their seeds, often enveloped in
chaffy ghimes, would be carried long distances by storms of
wind, and even if finally dropped into the sea would have so
much less distance to reach the land by means of surface cur-
rents ; and Mr. Darwin's experiments show that even cultivated
oats germinated after a hundred days' immersion in sea-water.
Othera have hispid awns by which they would become attached
to the feathers of birds, and there is no doubt this is an effective
mode of dispersal. But a still more important point is, probably,
that these plants are generally, if not always, wind-fertilized, and
are thus independent of any peculiar insects, which might be
wanting in the new country.
Why Easily Dispersed Plants have often Restricted Ranges.
— This last consideration throws light on a very curious point,
which has been noted as a difficulty by Sir Joseph Hooker, that
plants which have most clear and decided powers of dispei'sal by
wind or other means have not generally the widest specific
range; and he instances the small number of Compositse com-
mon to New Zealand and Australia. But in all these cases it
will, I think, be found that although the species have not a
wide range, the genera often have. In New Zealand, for in-
stance, the Coinpositoe are very abundant, there being no less
than 148 species, almost all belonging to Australian genera ;
yet only nine species, or less than one sixteenth of the whole,
are identical in the two countries. The explanation of this
is not difficult. Owing to their great powers of dispersal,
the Australian Conipositie reached New Zealand at a very re-
mote epoch, and such as were adapted to the climate and the
means of fertilization established themselves: but bein^: hiorhlv
specialized plants with great flexibility of organization, they soon
became modified in accordance with the new conditions, produc-
ing many special forms in different localities ; and these, spread-
ing widely, soon took possession of all suitable stations. Hence-
forth immigrants from Australia had to compete with these in-
digenous and well-established plants, and only in a few cases
were able to obtain a footing; whence it arises that we have
many Australian types, but few Australian species, in New Zea-
land, and both plienomena are directly traceable to the conibina-
Chap.XXU.] the FLOllA OF NEW ZEALAND. 465
tion of great powers of dispersal with a high degree of special-
ization. Exactly the same thing occurs with the still more high-
ly specialized Orchideae. These ai'e not proportionally so nu-
merous iu New Zealand (thirty -eight species), and this is no
doubt due to the fact that so many of them require insect-fer-
tilization, often by a particular family or genus (whereas almost
any insect will fertilize Compositee), and insects of all orders are
remarkably scarce in New Zealand. This would at once pre-
vent the establishment of many of the orchids which may have
reached the islands, while those which did find suitable fertiliz-
ers and other favorable conditions would soon become modified
into new species. It is thus quite intelligible why only three
species of orchids are identical in Australia and New Zealand,
although their minute and abundant seeds must be dispersed by
the wind almost as readily as the spores of ferns.
Another specialized group, the Scrophularinese, abounds in
New Zealand, where there are sixty-two species ; but though
almost all the genera are Australian, only three species are so.
Here, too, the seeds are usually very small, and the powers of
dispereal great, as shown by several European genera — Veron-
ica, Euphrasia, and Limosella being found in the Southern
Hemisphere.
Looking at the whole series of these Austifilo-New Zealand
plants, we find the most highly specialized groups — Compositie,
ScrophularinecB, Orchidese — with a small proportion of identical
species (one thirteenth to one twentieth), the less highly special-
ized— KanunculacesB, Onagrariae, and Ericese — with a higher
proportion (one ninth to one sixth), and the least specialized —
Juncese, Cyperaceae, and Graminese — with the high proportion in
each case of one fourth. These nine are the most important New
Zealand orders which contain species common to that country
and Australia and confined to them ; and the marked correspond-
ence they show between high specialization and want of specific
identity, while the generic identity is in all cases approximately
equal, points to the conclusion that the means of aiffusion are
in almost all plants ample when long periods of time are con-
cerned, and that diversities in this respect are not so important
in determining the peculiar character of a derived flora as
30
466 ISLAND LIFE. [Paut If.
adaptability to varied conditions, great powers of multiplica-
tion, and inherent vigor of constitution. This point will have
to be more fully discussed in treating of the origin of the
antarctic and north temperate members of the New Zealand
flora.
Summa^'y and Con-climon on the New Zealand Flora, — Con-
fining ourselves strictly to the direct relations between the plants
of New Zealand and of Australia, as I have done in the pre-
ceding discussion, I think I may claim to have shown that the
union between the two countries in the latter part of the Sec-
ondary epoch, at a time when Eastern Australia was widely sep-
arated from Western Australia (as shown by its geological for-
mation and by the contour of the sea-bottom), does sufficiently
account for all the main features of the New Zealand flora. It
shows why the basis of the flora is fundamentally Anstralian
both as regards orders and genera, for it was due to a direct
land-connection between the two countries. It shows also why
the great mass of typical Australian forms are unrepresented ;
for the Australian flora is typically western and temperate^ and
New Zealand received its immigrants from the eastern island,
which had itself received only a fragment of this flora, and from
the trajyical end of this island, and thus could only receive such
forms as were not exclusively temperate in character. It shows,
further, why New Zealand contains such a ver^^ large proportion
of tropical forms, for we see that it derived tlie main portion of
its flora directly from the tropics. Again, this hypothesis shows
us why, though the specially Australian genera in New Zealand
are largely tropical or subtropical, the specially Australian spe-
cies are wholly temperate or alpine; for as these are compara-
tively recent arrivals, they must have migrated across the sea in
the temperate zone, and these temperate and alpine forms are
exactly such as would be best able to establish themselves in a
country already stocked mainly by tropical forms and their mod-
ified descendants. This hypothesis further fulfils the conditions
implied in Sir Joseph Hooker's anticipation that "these great
differences [of the floras) will present the least difficulties to
whatever theory may explain the whole case;" for it shows
that these differences are directly due to the history and devel-
Chap. XXII.] TUE FLORA OF NEW ZEALAND. 467
opment of the Australian flora itself, while the resemblances de-
pend upon the most certain cause of all such broad resemblances
— actual land-connection.
One objection will undoubtedly be made to the above theory
— that it does not explain why some species of the prominent
Australian genera Acacia, Eucalyptus, Melaleuca, Grevillea,
etc., have not reached New Zealand in recent times along with
the other temperate forms that have established themselves.
But it is doubtful whether any detailed explanation of such a
negative fact is possible, while general explanations suflScient to
cover it are not wanting. Nothing is more certain than that
numerous plants never run wild and establish themselves in
countries where they, nevertheless, grow freely if cultivated ;
and the explanation of this fact given by Mr. Darwin — that they
are prevented doing so by the competition of better-adapted forms
' — is held to be sufficient. In this particular case, however, we
have some very remarkable evidence of the fact of their non-
adaptation. Tlie intercourse between New Zealand and Europe
has been the means of introducing a host of common European
plants — more than 150 in number as enumerated at the end of
the second volume of the " Handbook ;" yet, although the in-
tercourse with Australia has probably been greater, only two
j or three Australian plants have similarly established themselves.
I More remarkable still. Sir Joseph Hooker states, " I am inform-
ed that the late Mr. Bidwell habitually scattered Australian
seeds during his extensive travels in New Zealand." We may
be pretty sure that seeds of such excessively common and char-
acteristic groups as Acacia and Eucalyptus would be among
those so scattered, yet we have no record of any plants of these
or other peculiar Australian genera ever having been found wild,
still less of their having spread and taken possession of the soil
in the way that many European plants have done. We are,
then, entitled to conclude that the plants above referred to have
not established themselves in New Zealand (although their seeds
may have reached it) because they could not successfully com-
pete with the indigenous flora, which was already well establish-
ed and better adapted to the conditions of climate and of the
organic environment. This explanation is so perfectly in ac-
468 ISLAND LIFE. [Paht II-
cordance with a large body of well-known facts, including that
which is known to every one — how few of our oldest and hardi-
est garden-plants ever run wild — that the objection above stated
will, I feel convinced, have no real weight with any naturalists
who have paid attention to this class of questions.
Chap. XX I II.] ARCTIC PLANTS IN NEW ZEALAND. 469
CHAPTER XXIII.
ON THE ARCTIC ELEMENT IN SOUTH TEMPERATE FLORAS.
European Species and Genera of Plants in the Southern Hemisphere. — Aggressive
Power of the Scandinavian Flora. — Means by which Plants have Migiated from
North to South. — Newly Moved Soil as Affording Temporary Stations to Migrat-
ing Plants. — Elevation and Depression of the Snow-line as Aiding the Migration
of Plants. — Changes of Climate Favorable to Migration. — The Migration from
North to South has been long going on. — Geological Changes as Aiding Migra-
tion.— Proofs of Migration by Way of the Andes. — Proofs of Migration by Way
of the Himalayas and Southern Asia. — Proofs of Migration by Way of the African
Highlands. — Supposed Connection of South Africa and Australia. — The Endemic
Genera of Plants in New Zealand. — The Absence of Southern Types from the
Northern Hemisphere. — Concluding Remarks on the New Zealand and South
Temperate Floras.
We Lave now to deal with another portion of the New Zealand
flora which presents perhaps equal diflSculties — that which ap-
pears to have been derived from remote parts of the north and
south temperate zones ; and this will lead us to inquire into the
origin of the northern or arctic element in all the south tem-
perate floras.
More than one third of the entire number of New Zealand
genera (115) are found also in Europe, and even 58 species are
identical in these remote parts of the world. Temperate South
America has 74 genera in common with New Zealand, and there
are even 11 species identical in the two countries, as well as 32
which are close allies or representative species. A considerable
number of these northern or antarctic plants, and many more
which are representative species, are found also in Tasmania and
in the mountains of temperate Australia ; and Sir Joseph Hooker
gives a list of 38 species very characteristic of Europe and North-
ern Asia, but almost or quite unknown in the warmer regions,
which yet reappear in temperate Australia. Other genera seem
altogether antarctic — that is, confined to the extreme southern
470 ISLAND LIFE. [Pjust IL
lands and islands ; and these often Lave representative species
in Sontbem America, Tasmania, and Xew Zealand, while others
occur only in one or two of these areas. Many north temperate
genera also occur in the mountains of South Africa. On the
other hand, few, if any, of the peculiar Australian or antarctic
types have spread northward, except some of the former which
have reached the mountains of Borneo, and a few of the latter
which spread along the Andes to Mexico.
On these remarkable facts, of which I have given but the
barest outline, Sir Joseph Hooker makes the following sugges-
tive observations:
" When I take a comprehensive view of the vegetation of the
Old "World, I am struck with the appearance it presents of there
being a continuous current of vegetation (if I may so fancifully
express myself) from Scandinavia to Tasmania ; along, in short,
the whole extent of that arc of the terrestrial sphere which pre-
sents the greatest continuity of land. In the first place, Scan-
dinavian genera, and even species, reappear everywhere from
Lapland and Iceland to the tops of the Tasmanian Alps — in rap-
idly diminishing numbers, it is true, but in vigorous develop-
ment througliout. They abound on the Alps and Pyrenees, pass
on to the Caucasus and Ilimalava ; tlieiice tliev extend alons: the
Kliasia Mountains, and those of the peninsulas of India to those
of Ceylon and the Malayan Archipelago (Java and Borneo), and
after a hiatns of SO-' tlicy appear on the Alps of Xew South
Wales, Victoria, and Tasmania, and beyond these again on those
of Kaw Zealand and the antarctic islands, many of the species
remaining unchanged tlirungliout I It matters not what the
vegetation of the bases and Hanks of these mountains may be;
the northern species may be associated with alpine forms of
(ierinanic, Sii)erian, Oriental, Chinese, American, Malayan, and
finally Australian and antarctic types; but whereas these are all,
more or less, local assemblages, the Scandinavian asserts his pre-
rogative of ubi(|nity from Britain to beyond its anti])odes."*
It is impossible to place the main facts more forcibly before
the reader than in the above striking passage. It shows clearly
* Introductory cssny *'0n llie Flora of Aiistrnlin," p. 103.
Chap.XXIIL] arctic PLANTS IN NEW ZEALAND. 471
that this portion of the New Zealand flora is due to wide-spread
causes which have acted with even greater effect in otlier south
temperate lands, and that in order to explain its origin we must
grapple with the entire problem of the transfer of the north
temperate flora to the Southern Hemisphere. Taking, there-
fore, the facts as given by Sir Joseph Hooker in the works al-
ready referred to, I shall discuss the whole question broadly,
and shall endeavor to point out the general laws and subordi-
nate causes that, in my opinion, have been at work in bringing
about the anomalous phenomena of distribution he has done so
much to make known and to elucidate.
Affff7*e88ive Power of the Scandinavian Flora, — The first im-
portant fact bearing upon this question is the wonderful aggres-
sive and colonizing power of the Scandinavian flora, as shown
by the way in which it establishes itself in any temperate country
to which it may gain access. About 150 species have thus es-
tablished themselves in New Zealand, often taking possession of
large tracts of country ; about the same number are found in
Australia, and nearly as many in the Atlantic states of America,
where they form the commonest weeds. Whether or not wo
accept Mr. Darwin's explanation of this power as due to devel-
opment in the most extensive land area of the globe where com-
petition has been most severe and long-continued, the fact of
the existence of this power remains, and wo can see how im-
portant an agent it nmst be in the formation of the floras of
any lands to which these aggressive plants have been able to
gain access.
But not only are these plants pre-eminently capable of hold-
ing their own in any temperate country in the world, but they
also have exceptional powers of migration and dispersal over
seas and oceans. This is especially well shown by the case of
the Azores, where no less than 400 out of a total of 478 flower-
ing plants are identical with European species. These islands
are more than 800 miles from Europe, and, as we have already
seen in Chapter XIL, there is no reason for supposing that
they have ever been more nearly connected with it than they
are now, since an extension of the European coast to the 1000-
fathom line would very little reduce the distance. Now it is a
472 ISLAND LIFE, [Part n.
most interesting and suggestive fact that more than lialf the
European genera wliich occur in the Australian flora occur also
in the Azores, and in several cases even the species are identical
in both/ The importance of such a case as this cannot be exag-
gerated, because it affords a demonstration of the power of the
very plants in question to pass over wide areas of sea — some, no
doubt, wholly through the air, carried by storms in the same
way as the European birds and insects which annually reach the
Azores ; others by floating on the waters, or by a combination of
the two methods ; while some may have been carried by aquatic
birds, to whose feathers many seeds have the power of attaching
themselves. We have in such facts as these a complete disproof
of the necessity for those great changes of sea and land which
are continually appealed to by those who think land-connection
the only efficient means of accounting for the migration of ani-
mals or plants ; but, at the same time, we do not neglect to make
the fullest use of such moderate changes as all the evidence at
our command leads us to believe have actually occurred, and es-
pecially of the former existence of intermediate islands, so often
indicated by shoals in the midst of the deepest oceans.
Means hy which Plants have Migrated from North to South.
— But if plants can thus pass in considerable numbers and variety
over wide seas and oceans, it must be yet more easy for them to
traverse continuous areas of land, wherever mountain-chains of-
fer suitable stations at moderate intervals on which they might
temporarily establish themselves. The facilities afforded for
the transmission of plants by mountains has hardly received
sufficient attention. The numerous land-slips, the fresh surfaces
of broken rock and precipice, the debris of torrents, and the
moraines deposited by glaciers afford numerous unoccupied sta-
tions on which wind-borne seeds have a good chance of germi-
natinc:. It is a well-known fact that fresh surfaces of soil or
rock, such as are presented by railway cuttings and embank-
ments, often produce plants strange to the locality, which sur-
vive for a few years, and then disappear as the normal vegeta-
((
* Hooker, **0n tlie Flora of Austrnlin,'' p. 05 ; H. C Wntson, in Godman*g
Azores," |)p. 278 !>8r..
Chap.XXIIL] arctic PLANTS IN NEW ZEALAND. 473
tion gains strength and permanence.* But such a surface will,
in the meantime, have acted as a fresh centre of dispersal ; and
thus a plant might pass on step by step, by meansi of stations
' As this is a point of great interest in its bearing on the dispersal of plants by
means of mountain-ranges, I have endeavored to obtain a few iUustrative facts :
1. Mr. William Mitten, of Hurst Pierpont, Sussex, informs me that when the Lon-
don and Brighton Railway was in progress in his neighborhood, Meliiotus vulgaris
made its appearance on the banks, remained for several years, and then altogether
disappeared. Another case is that of Diplotaxia nmralis^ which formerly occurred
only near the sea-coast of Sussex and at Lewes ; but since the ruilwny was made
has spread along it, and still maintains itself abundantly on the railway banks, though
rarely found anywhere else.
2. A correspondent in Tasmania informs me that whenever the virgin forest is
cleared in that island there invariably comes up a thick crop of a plant locally known
as fire-weed — a species of Senecio, probably S, auntralis. It never grows except
where the fire has gone over the ground, and is unknown except in such places.
My correspondent adds : ** This autumn I went back about thirty-five miles through
a dense forest, along a track marked by some prospectors the year before, and in one
spot where they had camped, and the fire had burned the fallen logs, etc., there was
a fine crop of * fire-weed.* All around for many miles was a forest of the largest
trees and dense scrub." Here we have a case in which burnt soil and ashes favor
the germination of a particular plant, whose seeds are easily canied by the wind, and
it is not difficult to see how this peculiarity might favor the dispersal of the species
for enormous distances, by enabling it temporarily to grow and produce seeds on
burnt spots.
3. In answer to an inquiry on this subject, Mr. H. C. Watson has been kind
enough to send me a detailed account of the progress of vegetation on the railway
banks and cuttings about Thames Ditton. This account is written from memory ;
but as Mr. Watson states that he took a great interest in watching the process year
by year, there can be no reason to doabt the accuracy of his memory. I give a few
extracts which bear especially on the subject we are discussing :
*' One rather remarkable biennial plant appeared early (the second year, as I rec-
ollect) and renewed itself in either two or three yeare; namely, hatU tinc.toria — a spe-
cies usually supposed to be one of our introduced, but pretty well naturalized, plants.
The nearest stations then or since known to me for this Isatis are on chalk about
Guildford, twenty miles distant. There were two or three plants of it at firat, never
more than half a dozen. Once since I saw a plant of Isatis on the railway bank
near Vauxhall.
** Close by Ditton Station three species appeared which may be called interlopers.
The biennial Barharea precox^ one of these, is the least remarkable, because it
might have come as seed in the earth from some garden, or possibly in the Thames
gravel (used as ballast). At first it increased to several plants, then became less
numerous, and will soon, in all probability, become extinct, crowded out by other
plants. The biennial Petroselinum segetum was at first one very luxuriant plant on
the slope of the embankment. It increased by seed into a dozen or a score, and is
now nearly, if not quite, extinct. The third species is Unaria purpurea^ not stiictly
474 ISLAND LIFE. [Pakt II.
temporarily occupied, till it reached a district where, the general
conditions being more favorable, it was able to establish itself
as a permanent member of the flora. Sucli, generally speaking,
a British plant, but one established in some places on old walls. A single root of it
appeared on the chalk facing of the embankment by Ditton Station. It has remained
there several years and grown into a vigorous specimen. Two or three smaller ex-
amples are now seen by it, doubtless sprung from some of the hundreds or thoa-
sands of seeds shed by the original one plant. The species is not included in Salmon
and Brewer's "Flora of Suri-ev."
**The main line of the railway has introduced into Ditton parish tlie perennial
Arabis hirsuta, likely to become a permanent inhabitant. The species is found on
the chalk and greensand miles away from Thames Ditton ; but neither in this parish
nor in any adjacent parish, so far as known to myself or to the authora of the flora
of the county, does it occur. Some years after the railway was made a single root
of this Arabis was observed in the brickwork of an arch by whicli the railway is car*
ried over a public road. A year or two aftei^wards there were three or four plants.
In some later year I laid some of the ripened seed-pods between t)ie bricks in places
where the mortar had partly crumbled out. Now there are several scores of speci-
mens in the brickwork of the arch. It is presumable that the fii*st seed may have
been brought from Guildford. But how could it get on to the perpendicular face of
the brickwork ?
"The bee orchis {Ophrys apt/era), plentiful on some of the chalk lands in Surrey,
is not a species of Thames Ditton, or (as I presume) of any adjacent parish. Thus,
I was greatly surprised some yeai*s back to see about a hundred examples of it in
flower in one clavev field eitlier on the outskirts of Thames Ditton or just within the
limits of the ndjoining parish of Cobliam. I had crossed this same field in a former
year wiihout observing tlie Ophrys there. And on finding it in the one field, I close-
ly searched the surrounding fields and copses, without finding it anywhere else,
(iradually the plants becnme fewer and fewer in that one field, and some six or
eight years after its first discovery tiicre the species had quite disnj)peared again. I
guessed it had been introduced with chalk, but could obtain no evidence to show
this."
4. Mr. A. Bennett, of Croydon, has kindly furnished mo with some information on
the temporary vejjetation of the banks and cuttings on the railway from Yarmouth
to Caistor, in Norfolk, where it passes over extensive sandy dunes with a sparse veg-
etation. The first year after the railway was made, the bsiiiks produced abundance
of (Knothera cdoruta and Delphinium Ajavis (the latter only known thirty miles off
in corn-fields in Cambridgeshire), with Atriplex pntula and A.xhlloidea. Gradual-
ly the native sand-plants — Carices, grasses, Calium verum^ etc. — established them-
selves, and year by j.ear covered more ground, till the new introductions almost com-
pletely disa])peared. The same phenomenon was observed ifi Cambridgeshire between
Chesterton and Newmarket, where, the soil being ditlercnt, Stti/aria vudiu and other
annuals appeared in large patches ; but these soon gave way to a permanent vegeta-
tion of grasses, composites, etc., so that in the third year no Stellaria was to be seen.
5. Mr. T. Kirk (writing in 1878) states that **in Auckland, where a dense sward
Ohap.XXIIL] AUCnC PLANTS IN NEW ZEALAND. 475
was probably the process by which the Scandinavian flora has
made its way to the Southern Hemisphere; but it could hardly
have done so to any important extent without the aid of those
powerful causes explained in our eighth chapter — causes which
acted as a constantly recurrent motive power to produce that
" continuous current of vegetation " from north to south across
the whole width of the tropics referred to by Sir Joseph Hooker.
Those causes were, the repeated changes of climate which, dur-
ing all geological time, appear to have occurred in both hemi-
spheres, culminating at rare intervals in glacial epochs, and which
have been shown to depend upon changes of eccentricity of the
earth's orbit and the occurrence of summer or winter in aphelion,
in conjunction with the slower and more irregular changes of
geographical conditions; these combined causes acting chiefly
through the agency of heat -bearing oceanic currents, and of
snow- and ice-collecting highlands. Let us now briefly consider
liow such changes would act in favoring the dispersal of plants.
Klevation and Depression of the Snow -line as Aiding the
of grass is soon formed, single specimens of the European Milk Thistle {Carduus
marianus) have been known for the past fifteen vears ; but although they seeded freely,
the seeds had no opportunity of germinating, so that the thistle did not spread. A
remarkable exception to this rule occurred during the formation of the Onehunga
liailway, where a few seeds fell on disturbed soil, grew up, and flowered. The rail-
way works being suspended, the plant increased rapidly, and spread wherever it could
find disturbed soil."
Again, **The fiddle-dock {Rumex pulcher) occurs in great abundance on the for-
mation of new streets, etc., but soon becomes comparatively rare. It seems proba-
bio that it was one of the earliest plants naturalized here, but that it partially died
out, its buried seeds retaining their vitality."
Medicago saliva and Apium graveolent are also noted as escapes from cultivation
which maintain themselves for a time, but soon die out.*
The preceding examples of the temporary establishment of plants on newly ex-
posed soil, often at considerable distances from the localities they usually inhabit,
might, no doubt, by further inquiry be gieatly multiplied ; but, unfortunately, the
phenomenon has received little attention, and is not even referred to in the elaborate
work of De CandoUe (**Geographie Botanique Raisonnco"), in which almost every
other aspect of the dispersion and distribution of plants is fully discussed. Enough
has been advanced, however, to show that it is of constant occurrence, and from the
point of view here advocated it becomes of great importance in explaining the almost
world-wide distribution of many common plants of the north temperate zone.
* TranmOimu qf the N«w Zealand IntUUtU^ VoL X., p. 867.
476 ISLAND LIFE. [Pari 11.
Migration of Plants. — We have endeavored to show (in an
earlier portion of this volume) that wherever geograpliical or
physical conditions were such as to produce any considerable
amount of perpetual snow, this would be increased whenever a
high degree of eccentricity concurred with winter in aphelion,
and diminislied during tlie opposite phase. On all mountain-
ranges, therefore, which reached above the snow -line there
would bo a periodical increase and decrease of snow ; and when
there were extensive areas of plateau at about the same level,
the lowering of the snow-line might cause such an increased ac-
cumulation of snow as to produce great glaciere and ice-fields,
such as we have seen occurred in South Africa during the last
period of high eccentricity. But along with such depression of
the line of perpetual snow there would be a corresponding de-
pression of the alpine and sub-alpine zones suitable for the
growth of an arctic and temperate vegetation, and, what is per-
haps more important, the depression would necessarily produce
a great extetision of the area of these zones on all high moun-
tains, thus affording a number of new stations suitable for such
temperate plants as might first reach them. But just above and
below the snow-line is the area of most powerful disintegration
and deiiudution, from the alternate action of frost and sun, of
ice and water ; and thus the more extended area would be sub-
ject to the constant occurrence of land-slips, berg-falls, and floods,
with their accompanying accumulations of debris and of alluvial
soil, affording innumerable stations in which solitary wind-borne
seeds might germinate and temporarily establish themselves.
Tliis lowering and rising of the snow-line each 10,500 years
during periods of high eccentricity would occur in the Xorthern
and Southern hemispheres alternately; and where there were
high mountains within the tropics the two would probably over-
lap each other, so that the northern depression would make itself
felt in a slight degree even across the equator some way into the
Southern Hemisphere, and vt'ce verm ; and even if the difference
of the height of perpetual snow at the two extremes did not av-
erage more than a few hundred feet, this would be amply suffi-
cient to supply the new and unoccupied stations needful to fa-
cilitate the migration of plants.
Chap. XXIII.] ARCTIC PLANTS IN NEW ZEALAND. 477
But the differences of temperature in the two hemispheres
caused by the sun being in perihelion in the winter of the one
while it was in aphelion during the same season in the other
would necessarily lead to increased aerial and marine currents,
as already explained; and whenever geographical conditions
were such as to favor the production of glaciation in any area,
these effects would become more powerful, and would further
aid in the dispei*sal of the seeds of plants.
Changes of Climate Favorable to Migration. — It is clear, then,
that during periods when no glacial epochs were produced in the
Northern Hemisphere, and even when a mild climate extended
over the whole polar area, alternate changes of climate favoring
the dispersal of plants would occur on all high mountains, and
with particular force on such as rise above the snow-line. But,
during that long-continued, though comparatively recent, phase
of high eccentricity which produced an extensive glaciation in
the Northern Hemisphere and local glaciations in the Southern,
these risings and lowerings of the snow-line on all mountain-
ranges would have been at a maximum, and would have been
increased by the depression of the ocean which must have arisen
from such a vast bulk of water being locked up in land-ice, and
which depression would have produced the same effect as a gen-
eral elevation of all the continents. At this time, too, aerial
currents would have attained their maximum of force in both
hemispheres ; and this would greatly facilitate the dispereal of
all wind-borne seeds as well as of those carried in the plumage
or in the stomachs of birds, since we have seen how vastly the
migratory powers of birds are increased by a stormy atmosphere.
Mlgraiion from North to South has been long going on, — Now,
if each phase of colder and warmer mountain-climate, each al-
ternate depression and elevation of the snow-line, only helped
on the migration of a few species some stages of the long route
from the north to the south temperate regions, yet during the
long course of the Tertiary period there might well have arisen
that representation of the northern flora in the Southern Hemi-
sphere which is now so conspicuous. For it is very important to
remark that it is not the existing flora alone that is represented,
such as might have been conveyed during the last glacial epoch
478 ISLAND LIFE. [Part II.
ouly ; but we find a whole series of northern types evidently of
varying degrees of antiquity, while even some genera character-
istic of the Southern Hemisphere appear to have been originally
derived from Europe. Thus Eucalyptus and Metrosideros have
been determined by Dr. Ettinghausen from their fruits in the
Eocene beds of Sheppey ; while Pimelea, Leptomeria, and four
genera of Proteacese have been recognized by Professor Heer in
the Miocene of Switzerland ; and the former writer has detected
fifty-five Australian forms in the Eocene plant- beds of Haring
(? Belgium).* Then we have such peculiar genera as Pachychla-
don and Notothlaspi of New Zealand said to have affinities with
arctic plants; while Stilbocarpa, another peculiar New Zealand
genus, has its nearest allies in the Himalayan and Chinese Ara-
lias. Following these are a whole host of very distinct species of
northern genera which may date back to any part of the Terti-
ary period, and which occur in every south temperate land. Then
we have closely allied representative species of European or arc-
tic plants, and, lastly, a number of identical species ; and these
two classes are probably due entirely to the action of the last
great glacial epoch, whose long continuance, and the repeated
fluctuations of climate with which it commenced and termi-
nated, rendered it an agent of sufficient power to have brought
about this result.
* Sir Joseph Hooker informs me tliat lie considers these identificntions worthless,
nnd Mr. Henthiim has nlso written very strongly against the value of similar identifi-
cations hy Ileer and Unger. Giving due weight to the opinions of these eminent
botanists, we must admit that Australian genera have not yet been demonstrated to
have existed in lunope during the Tertiary period ; but, on the other hand, the evi-
dence that they did so appears to have some weight, on account of the improbability
that the numerous resemblances to Australian ]»Iants which have been noticed by
different observers should all be illusory ; while the well-established fact of the
former wide distribution of many trojjical or now restricted types of jdants and nni-
maN, so froipiently illustrated in the present volume, removes the antecedent iniprob-
ability which is supposed to attach to such identifications. 1 am myself the more
inclined to accept them because, according to the views here advocated, such migra-
tions must have taken place at remote as well as at recent epochs ; and the preserva-
tion of some of these tyi)es in Australia while they have bec<mie extinct in Europe
is exactly paralleled by numerous facts in the distribution of animals which have
been already referred to in Chapter XIX. and elsewhere in this volume, and also re-
peatedly in my larger work.
Chap.XXIIL] arctic PLANTS IN NEW ZEALAND. 479
Here, then, we have that constant or constantly recurrent proc-
ess of dispersal acting throughout long periods with varying
power — that " continuous current of vegetation," as it has been
termed — which the facts demand ; and the extraordinary phe-
nomenon of the species and genera of European and even of
arctic plants being represented abundantly in South Africa,
Australia, and New Zealand thus adds another to the long series
of phenomena which are rendered intelligible by frequent alter-
nations of warmer and colder climates in either hemisphere, cul-
minating, at long intervals and in favorable situations, in actual
glacial epochs.
Geological Changes as Aiding Migration. — It will be well also
to notice here that there is another aid to dispersion, dependent
upon the changes effected by denudation during the long peri-
ods included in the duration of the species and genera of plants.
A considerable number of the plants of Europe of the Miocene
period were so much like existing species that although they
have generally received fresh names they may well have been
identical ; and a large proportion of the vegetation during the
whole Tertiary period consisted of genera which are still living.*
But from what is now known of the rate of subaerial denuda-
tion we are sure that during each division of this period many
mountain-chains must have been considerably lowered, while we
know that some of the existing ranges have been greatly ele-
vated. Ancient volcanoes, too, have been destroyed by denuda-
tion, and new ones have been built up, so that we may be quite
sure that ample means for the transmission of temperate plants
across the tropics may have existed in countries where they are
now no longer to be found. The great mountain masses of Gui-
ana and Brazil, for example, must have been far more lofty be-
fore the sedimentary covering was denuded from their granitic
bosses and metamorphic peaks, and may have aided the southern
* Out of forty-two genera from the Eocene of Sheppey, enumemted by Dr. Etting-
Imusen in the Geological Mivjazine for January, 1880, only two or three appear to
be extinct, while there is a most extraordinary intermixture of tropical and temper-
ate forms— Musa, Nipa, and Victoria, with Corylus, Prunus, Acer, etc. The rich
Miocene flora of Switzerland, described by Professor Hecr, presents a still larger
proportion of living genera.
480 ISLAND LIFE. [Part 1L
migration of plants before the final elevation of the Andes.
And if Africa presents us with an example of a continent of
vast antiquity we may be sure that its great central plateaus
once bore far loftier mountain-ranges ere they were reduced to
their present condition by long ages of denudation.
Proofs of Migration hy Way of the Andes, — We are now pre-
pared to apply the principles above laid down to the explana-
tion of the character and aflSnities of the various portions of the
north temperate flora in the Southern Hemisphere, and especial-
ly in Australia and New S^ealand.
At the present time the only unbroken chain of highlands
and mountains connecting the arctic and north temperate with
the antarctic lands is to be found in the American continent, the
only break of importance being the comparatively low Isthmus
of Panama, where there is a distance of about 300 miles occu-
pied by rugged forest -clad hills, between the lofty peaks of
Veragua and the northern extremity of the Andes of New Gra-
nada. Such distances are, as we have already seen, no barrier to
the diffusion of plants ; and we should accordingly expect that
this great continuous mountain-chain has formed the most effec-
tive agent in aiding the southward migration of the arctic and
north temperate vegetation. We do find, in fact, not only that
a large number of northern genera and many species are scat-
tered all along this line of route, but that at the end of tlie long
journey, in Southern Chili and Fuegia, they have established
themselves in sqch numbers as to form an important part of the
flora of those countries. From the lists given in the works al-
ready referred to, it appears that there are between sixty and
seventy northern genera in Fuegia and Southern Chili, while
about forty of the species arc absolutely identical with those of
Europe and the arctic regions. Considering how comparatively
little the mountains of south temperate America are yet known,
this is a very remarkable result, and it proves that the transmis-
sion of species must have gone on up to compamtively recent
times. Yet, as only a few of these species are now found along
the line of migration, we see that they only occupied such sta-
tions temporarily ; and we may connect their disappearance with
the passing-away of the last glacial period, which, by raising the
Chap. XXIII.] ARCTIC PLANTS IN NEW ZEALAND. 481
snow-line, reduced the area on which alone they could exist, and
exposed them to the competition of indigenous plants from the
belt of country immediately below them.
Now, just as these numerous species and genera have un-
doubtedly passed along the great American range of mountains,
although only now found at its two extremes, so others have
doubtless passed on farther ; and have found more suitable sta-
tions or less severe competition in the antarctic continent and
islands, in New Zealand, in Tasmania, and even in Australia it-
self. The route by which they may have reached these coun-
tries is easily marked out. Immediately south of Cape Horn,
at a distance of only 500 miles, are the South Shetland Islands
and Graham's Land, whence the antarctic continent or a group
of large islands probably extends across or around the south
polar area to Victoria Land, and thence to Adelie Land. The
outlying Young Island, 12,000 feet high, is about 750 miles
south of the Macquarie Islands, which may be considered a
southeni outlier of the New Zealand group ; and the Macquarie
Islands are about the same distance from the 1000-fathom line,
marking the probable southern extension of Tasmania. Other
islands may have existed at intermediate points ; but, even as it
is, these distances are not greater than we know are traversed
by plants both by flotation and by aerial currents, especially in
such a stormy atmosphere as that of the antarctic regions.
Now we may further assume that what we know occurred with-
in the Arctic Circle also took place in the Antarctic — that is,
that there have been alternations of climate during which some
portion of what are now ice-clad lands became able to support
a considerable amount of vegetation.* During such periods
there would be a steady migration of plants from all southern
circumpolar countries to people the comparatively unoccupied
continent; and the southern extremity of America being con-
siderably the nearest, and also being the best stocked with those
* The recent discovery of a rich flora on rocky peaks rising out of the continental
ice of Greenland, as well as the abundant vegetation of the highest northern latitudes,
renders it possible that even now the antarctic continent may not be wholly desti-
tiite of vegetation, although its climate and physical condition are far less favorable
than those of the arctic lands.
?,i
482 ISLAND LIFE. [Part IL
northern types which have such great powers of migration and
colonization, such plants would form the bulk of the antarctic
vegetation, and during the continuance of the milder southern
climate would occupy the whole area.
When the cold returned and the land again became ice-clad,
these plants would be crowded towards the outer margins of
the antarctic land and its islands, and some of them would find
their way across the sea to such countries as offered on their
mountain summits suitable cool stations; and as this process of
alternately receiving plants from Chili and Fuegia and trans-
mitting them in all directions from the central antarctic land
may have been repeated several times during the Tertiary peri-
od, we have no difficulty in understanding the general commu-
nity between the European and antarctic plants found in all
south temperate lands. Kerguelen Land and the Crozets are
within about the same distance from the antarctic continent as
New Zealand and Tasmania, and we need not therefore be sur-
prised at finding in each of these islands some Fuegian species
which have not reached the others. Of course there will re-
main difficulties of detail, as there always must when we know
so imperfectly the past changes of the eartli's surface and the
history of the particular plants concerned. Sir Joseph Hooker
notes, for example, the curious fact that several Compositoe com-
mon to three such remote localities as the Auckland Islands,
Fiicgia, and Kerguelen Land have no pappus or seed- down,
while such as have pappus are in no case connnon even to two
of these islands. Without knowing the exact history and dis-
tribution of the genera to which these plants belong, it would
be useless to offer any conjecture, except that they are ancient
forms which may have survived great geographical changes, or
may have some peculiar and exceptional means of dispersion.
Proof H of Migration hy Way of the Himalayas and Southern
Asia, — But although we may thus explain the presence of a
considerable portion of the European element in the floras of
New Zealand and Australia, we cannot account for the whole
of it bv this means, because Australia itself contains a host of
European and Asiatic genera of which we find no trace in New
Zealand or South America, or any other antarctic land. We
Chap. XXIII.] ARCTIC PLANTS IN NEW ZEALAND. 483
find, in fact, in Australia two distinct sets of European plants.
First, wo have a number of species identical with those of
Northern Europe or Asia (of the most characteristic of which
— thirty-eight in number — Sir Joseph Hooker gives a list) ; and,
in the second place, a series of European genera, usually of a
somewhat more southern character, mostly represented by very
distinct species, and all absent from New Zealand ; such as
Clematis, Papaver, Cleome, Polygala, Lavatera, Ajuga, etc. Now
of the first set — the North European species-^about three fourths
occur in some parts of America, and about half in soutli tem-
perate America or New Zealand ; whence we may conclude that
most of these, as well as some others, have reached Australia by
the route already indicated. The second set of Australo-Euro-
pean genera, however, and many others characteristic of tlie
South European or the Himalayan flora, have probably reached
Australia by way of the mountains of Southern Asia, Borneo,
the Moluccas, and New Guinea, at a somewhat remote period
when loftier ranges and some intermediate peaks may have ex-
isted, sufiicient to carry on the migration by the aid of the
alternate climatal changes which are known to have occurred.
The long belt of Secondary and Palaeozoic formations in East
Australia from Tasmania to Cape York, continued by the lofty
ranges of New Guinea, indicates the route of this immigration,
and suflSciently explains how it is that these Northern types are
almost wholly confined to this part of the Australian continent.
Some of the earlier immigrants of this class no doubt passed
over to New Zealand and now form a portion of tlie peculiar
genera confined to these two countries ; but most of them are
of later date, and have thus remained in Australia only.
Proofs of Migration by Way of the African Ilighlanda. — It
is owing to this twofold current of vegetation flowing into Aus-
tralia by widely different routes that we have in this distant
land a better representation of tlie European flora, both as re-
gards species and genera, than in any other part of the Southern
Hemisphere ; and, so far as I can judge of the facts, there is no
general phenomenon — that is, nothing in the distribution of
genera and other groups of plants as opposed to cases of indi-
vidual species — that is not fairly accounted for by such an ori-
484 ISLAND LIFE. [PAarll.
gin. It further receives support from the case of South Africa,
which also contains a large and important representation of the
northern flora. But here we see no indications (or very slight
ones) of that southern influx which has given Australia such a
community of vegetation with the antarctic lands. There are
no less than sixty genera of strictly north temperate plants in
South Africa, none of which occur in Australia ; while very few
of the species so characteristic of Australia, New Zealand, and
Fuegia are found there. It is clear, therefore, that South Africa
has received its European plants by the direct route through
the Abyssinian highlands and the lofty equatorial mountains,
and mostly at a distant period, when the conditions for migra-
tion were somewhat more favorable than they are now. The
much greater directness of the route from Northern Europe to
South Africa than to Australia, and the existence even now of
lofty mountains and extensive highlands for a large portion of
the distance, will explain (what Sir Joseph Hooker notes as " a
very curious fact") why South Africa has more very northern
European genera than Australia, while Australia has more iden-
tical species and a better representation, on the whole, of tlie
European flora — this being clearly due to the large influx of
species it has received from the antarctic islands, in addition to
those which have entered it by way of Asia. The greater dis-
tance of South Africa even now from any of these islands, and
the much deeper sea to the south of the African continent, than
in the case of Tasmania and New Zealand, indicating a smaller
recent extension southward, are all quite in harmony with the
facts of distribution of the northern flora above referred to.
/Sf/pj)osed Co7inecti07i of South Africa a?id Australia, — There
remains, however, the small amount of direct affinity between
the vegetation of South Africa and that of Australia, New Zea-
land, and temperate South America, consisting in all of fifteen
genera, five of which are confined to Australia and South Af-
rica, while several natural ordei^s are better represented in these
two countries than in any other part of the world. This re-
semblance has been supposed to imply some former land-con-
nection of all the great southern lands, but it appears to me that
any such supposition is wholly unnecessary. The differences
Chap. XXIII.] ARCTIC PLANTS IN NEW ZEALAND. 485
between the faunas and floras of these conntries are too great
and too radical to render it possible that any such connection
should have existed except at a very remote period. But if we
liave to go back so far for an explanation, a much simpler one
presents itself, and one more in accordance with what wo have
learned of the general permanence of deep oceans and the radi-
cal changes that have taken place in the distribution of all forms
of life. Just as we explain the presence of marsupials in Aus-
tralia and America, and of Centetidte in Madagascar and the
Antilles, by the preservation in these localities of remnants of
once wide-spread types, so we should prefer to consider the few
genera common to Australia and South Africa as remnants of
an ancient vegetation, once spread over the northern hemi-
sphere, driven southward by the pressure of more specialized
types, and now finding a refuge in these two widely separated
southern lands. It is suggestive of such an explanation that
these genera are either of very ancient groups, as Conifers and
Cycads, or plants of low organization, as the Restiaceae, or of
world-wide distribution, as Melanthacese.
The Endemic Genera of Plants in New Zealand, — Returning
now to the New Zealand flora, with which we are more espe-
cially concerned, there only remains to be considered the pecul-
iar or endemic genera which characterize it. These are thirty-
two in number, and are mostly very isolated. A few have affini-
ties with arctic groups, others with Himalayan or Australian
genera ; several are tropical forms, but the majority appear to
be altogether peculiar types of world-wide groups, as Legu-
minosiB, Saxifrage©, Compositee, Orchideae, etc. We must evi-
dently trace back these peculiar forms to the earliest immi-
grants, either from the north or from the south ; and the great
antiquity we are obliged to give to New Zealand — an antiquity
supported by every feature in its fauna and flora, no less than
by its geological structure and its extinct forms of life* — affords
* Dr. Hector notes the occurrence of the genus Dnmmnra in Triassic deposits, while
in tlie Jurassic period New Zealand produced the genera Palseozamin, Olenndriuni,
Alethopteris, Camptopteris, Cycadites, Kchinostrobus, etc., nil Indian forms of the
same age. Keocominn beds contain a true dicotyledonous leaf with Dammara and
Araacaria. The Cretaceous deposits have produced a rich flora of dicotvledonous
486 ISLAND LIFE. [Part II.
ample time for the changes in the general distribution of plants,
and for those due to isolation and modification under the influ-
ence of changed conditions, which are manifested by the ex-
treme peculiarity of many of these interesting endemic forms.
The Absence of Soxdhern Types from the Northern Hemi-
sphere.— We have now only to notice the singular want of rec-
iprocity in the migrations of northern and southern types of
vegetation. In return for the vast number of European plants
which have reached Australia, not one single Australian plant
has entered any part of the north temperate zone, and the same
may be said of the typical southern vegetation in general, wheth-
er developed in the antarctic lands. New Zealand, South Amer-
ica, or South Africa. The farthest northern outliers of the
southern flora are a few genera of antarctic type on the Bor-
nean Alps; the genus Acsena, which lias a species in California ;
two representatives of the Australian flora — Casuarina and Sty-
lidium — in the peninsula of India; while China and the Philip-
pines have two strictly Australian genera of Orchideae — Microtis
and Thelymitra — as well as a Restiaceous genus. Several distinct
causes appear to liave combined to produce this curious inability
of the southern flora to make its way into the Northern Hemi-
sphere. The primary cause is, no doubt, the totally different
distribution of land in the two hemispheres, so tliat in the south
there is the minimum of land in the colder parts of the temper-
ate zone, and in the north the maximum. Tliis is well shown
by the fact that on the parallel of lat. 50° N. we pass over 240°
of land or shallow sea, while on the same parallel of south lati-
tude we have only 4° where we cross the southern part of Pata-
gonia. Again, the three most important south temperate land-
areas — south temperate America, South Africa, and Australia
— arc widely separated from each other, and have in all proba-
bility always been so; whereas the whole of the north temper-
ate lands are practically continuous. It follows that, instead of
plants, many of wliich are of the same genera as the existing flora; while the Mio-
cene and other Tertiary dejmsits produce plants apparently almost identical with
those now inhabiting the country (Transactions of the New Zealand Institute, Vol.
XI., 1870, p. 530). These facts agree well with the origin of the New Zealand flora
developed in the last chajiler.
Chap. XXIII.] ABCTIC PLANTS IN NEW ZEALAND. 487
the enormous northern area in which liighly organized and dom-
inant groups of plants have been developed gifted with great
colonizing and aggressive powers, we have in the south three
comparatively small and detached areas, in which rich floras
have been developed with special adaptations to soil, climate,
and organic environment, but comparatively impotent and in-
ferior beyond their own domain.
Another circumstance which makes the contest between the
northern and southern forms still more unequal is the much
greater hardiness of the former, from having been developed in
a colder region, and one where alpine and arctic conditions ex-
tensively prevail ; whereas the southern floras have been mainly
developed in mild regions to which they have been altogether
confined. While the northern plants have been driven north or
south by each succeeding change of climate, the southern species
have undergone comparatively slight changes of this nature,
owing to the areas they occupy being unconnected with the
ice -bearing antarctic continent. It follows that whereas the
northern plants find in all these southern lands a milder and
more equable climate than that to which they have been accus-
tomed, and are thus often able to grow and flourish even more
vigorously than in their native land, the southern plants would
find in almost every part of Europe, North America, or North-
ern Asia a more severe and less equable climate, with winters
that usually prove fatal to them even under cultivation. These
causes, taken separately, are very powerful, but when combined
they must, I think, be held to be amply sufficient to explain why
examples of the typical southern vegetation are almost unknown
in the north temperate zone, while a very few of them have ex-
tended so far as the northern tropic'
' The fact stated in the last edition of the ''Origin of Species" (p. 340) on the
authority of Sir Joseph Hooker, that Australian plants are rapidly sowing themselves
and becoming naturalized on the Neilgherry Mountains in the southern part of the
Indian Peninsula, though an exception to the rule of the inability of Australian plants
to become naturalized in the Northern Hemisphere, is yet quite in harmony with the
hypothesis here advocated. For not only is the climate of the Neilglierries more fa-
vorable to Australian plants than any part of the north temperate zone, but the
entire Indian Peninsula has existed for unknown ages as an islandf and thus possesses
the ''insular" characteristic of a comparatively poor and less developed flora and
488 ISLAND LIFE. [Part IL
Concluding Bemarks on the Last Two Chapters. — Our inquiry
into the external relations and probable origin of the fauna and
flora of New Zealand has thus led us on to a general theory
as to the cause of the peculiar biological relations between the
Northern and the Southern Hemispliere ; and no better or more
typical example could be found of the wide range and great in-
terest of the study of the geogmphical distribution of animals
and plants.
Tlie solution which has here been given of one of the most
difficult of this class of problems has been rendered possible
solely by the knowledge very recently obtained of the form of
the sea- bottom in the Southern Ocean, and of the geological
stnicture of the great Australian continent. Without this knowl-
edge we should have nothing but a series of guesses or probabil-
ities on which to found our hypothetical explanation, which we
have now been able to build up on a solid foundation of fact.
The complete separation of East from West Australia during
the Cretaceous period could never have been guessed till it was
established by the laborious explorations of the Australian ge-
ologists ; while the hypothesis of a comparatively shallow sea,
uniting New Zealand by a long route with tropical Australia,
while a profoundly deep ocean always separated it from temper-
ate Australia, would have been rejected as too improbable a
supposition for the foundation of even the most enticing theory.
Yet it is mainly by means of these two facts that we are en-
abled to give an adequate explanation of the strange anomalies
in the flora of Australia and its relation to that of New Zea-
land.
In the more general explanation of the relations of the vari-
ous northern and southern floras, I have shown what an impor-
tant aid to any such explanation is the tlieor}' of repeated changes
of climate, not necessarily of great amount, given in our eighth
chapter ; while the whole discussion justifies the importance at-
tached to the theory of the general permanence of continents
fauna ns compared with the truly *' continental" Malayan and Himalayan regions.
Australian plants are thus enabled to compete with those of the Indian reninsula
highlands with n fair chance of success.
Chaf.XXIIL] arctic PLANTS IN NEW ZEALAND. 489
and oceans, as demonstrated in Chapter VI., since any rational
explanation based upon facts (as opposed to mere unsupported
conjecture) must take such general permanence as a starting-
point. Tlie whole inquiry into the phenomena presented by
islands, which forms the main subject of the present volume,
has, I think, shown that this theory does afford a firm founda-
tion for the discussion of questions of distribution and dispersal ;
and that by its aid, combined with a clear perception of the
wonderful powers of dispersion and modification in the organic
world when long periods are considered, the most diflBcult prob-
lems connected with this subject cease to be insoluble.
490 ISLAND LIFE. [Pakt H,
CHAPTER XXIV.
SUMMARY AND CONCLUSION.
The Present Volume is the Development and Application of a Theory. — Statement
of the Biological and Physical Causes of Dispersal. — Investigation of the Facts qf
Dispersal. — Of the Means of Dispersal. — Of Geographical Changes Affecting Dis-
pei-sal. — Of Climatal Changes Affecting Dispersal. — The Glacial Epoch and its
Causes. — Alleged Ancient Glacial Epochs. — Warm Polar Climates and their Causes.
— Conclusions as to Geological Climates. — How far Different from those of Mr.
Croll. — Supposed Limitations of Geological Time. — Time Amply Sufficient both for
Geological and Biological Development. — Insular Faunas and Floras. — The North
Atlantic Islands. — The Galapagos. — St. Helena and the Sandwich Islands. — Gi*eat
Britain as a Recent Continental Island. — Borneo and Java. — Japan and Formosa.
— Madagascar as an Ancient Continental Island. — Celebes and New Zealand as
Anomalous Islands. — The Flora of New Zealand and its Oiigin. — The European
Element in the South Temperate Floras. — Concluding Remarks.
The present volume has gone over a very wide field both of
facts and theories, and it will be well to recall these to the read-
er's attention, and point out their connection with each other, in
a concluding chapter. I hope to be able to show tliat, although
at first sight somewhat fragmentary and disconnected, this work
is really the development of a clear and definite theory, and its
application to the solution of a number of biological problems.
That theory is, briefly, that the distribution of the various spe-
cies and groups of living things over the earth's surface, and
their aggregation in definite assemblages in certain areas, are
the direct result and outcome of a complex set of causes, which
may be grouped as "biological" and "physical." The biologi-
cal causes are mainly of two kinds — firstly, the constant tendency
of all organisms to increase in numbers and to occupy a wider
area, and their various powers of dispersion and migration
through which, when unchecked, they are enabled to spread
widely over the globe ; and, secondly, those laws of evolution
and extinction which determine the manner in which groups of
Chap. XXIV.] SUMMARY AND CONCLUSION. 491
organisms arise and grow, reach their maximum, and then dwin-
dle away, often breaking up into separate portions which long
survive in very remote regions. The physical causes are also
mainly of two kinds. We have, first, the geographical changes
which at one time isolate a whole fauna and flora, at another
time lead to their dispersal and intermixture with adjacent fau-
nas and floras — and it was hero important to ascertain and define
the exact nature and extent of these changes, and to determine
the question of the general stability or instability of continents
and oceans ; in the second place, it was necessary to determine
the exact nature, extent, and frequency of the changes of cli-
mate which have occurred in various parts of the earth, be-
cause such changes are among the most powerful agents in caus-
ing the dispersal and extinction of plants and animals. Hence
the importance attached to the question of geological climates
and their causes, which have been here investigated at some
length with the aid of the most recent researches of geologists,
physicists, and explorers. These various inquiries led on to an
investigation of the mode of formation of stratified deposits, with
a view to fix within some limits their probable age; and also to
an estimate of the probable rate of development of the organic
world ; and both these processes are shown to involve, in all
probability, periods of time less vast than have generally been
thought necessary.
The numerous facts and theories established in the First Part
of the work are then applied to explain the phenomena present-
ed by the floras and faunas of tlie chief islands of the globe,
which are classified, in accordance with their physical origin, in
three groups or classes, each of which is shown to exhibit cer-
tain well-marked biological features.
Having thus shown that the work is a connected whole, found-
ed on the principle of tracing out the more recondite causes of
the distribution of organisms, we will briefly indicate the scope
and object of the several chapters by means of which this gen-
eral conception has been carried out.
Beginning with simple and familiar facts relating to British
and European quadrupeds and birds, I have defined and shown
the exact character of " areas of distribution" as applied to spe-
492 ISLAND LIFE. [Pabt II.
cies, genera, and families, and have illustrated the subject by
maps showing the peculiarities of distribution of some well-
l^nown groups of birds. Taking, then, our British mammals
and land birds, I follow them over the whole area they inhabit,
and thus obtain a foundation for the establishment of " zoologi-
cal regions," and a clear insight into their character as distinct
from the usual geographical divisions of the globe.
The facts thus far established are then shown to be necessary
results of the " law of evolution." The nature and amount of
" variation " are exhibited by a number of curious examples ; the
origin, growth, and decay of species and genera are traced ; and
all the interesting phenomena of isolated groups and discontin-
uous generic and specific areas are shown to follow as logical
consequences.
The next subject investigated is the means by which the vari-
ous groups of animals are enabled to overcome the natural bar-
riers which often seem to limit them to very restricted areas,
how far those barriers are themselves liable to be altered or abol-
ished, and what are the exact nature and amount of the changes
of sea and land which our earth has undergone in past times.
This latter part of the inquiry is shown to be the most impor-
tant as it is the most fundamental ; and as it is still a subject of
controversy, and many erroneous views prevail in regard to it,
it is discussed at some length. Several distinct classes of evi-
dence are adduced to prove that the grand features of our globe
— the position of the great oceans and the chief land-areas — have
remained, on the whole, unchanged throughout geological time.
Our continents are show^n to be built up mainly of "shore-de-
posits ;" and even the chalk, which is so often said to be the
exact equivalent of the "globigerina ooze" now forming in mid-
Atlantic, is shown to be a comparatively shallow-water deposit
formed in inland seas, or in the immediate vicinity of land.
The general stability of continents has, however, been accom-
panied by constant changes of form, and insular conditions have
prevailed over every part in succession ; and the effect of such
changes on the distribution of organisms is pointed out.
We then approach the consideration of another set of changes
— those of climate — which have probably been agents of the
Chap. XXIV.] SUMMARY AND CONCLUSION. 493
first importance in modifying the specific forms as well as the
distribution of animals. Here, again, we find ourselves in the
midst of fierce controversies. The occurrence of a recent glacial
epoch of great severity in the Northern Hemisphere is now uni-
versally admitted, but the causes which brought it on are mat-
ter of dispute. But unless we can arrive at these causes, as well
as at those which produced the equally well demonstrated mild
climate in the arctic regions, we shall be quite unable to deter-
mine the nature and amount of the changes of climate which
have occurred throughout past ages, and shall thus be left with-
out a most important clew to the explanation of many of the
anomalies in the distribution of animals and plants.
I have therefore devoted three chapters to a full investigation
of this question. I have first given such a sketch of the most
salient facts as to render the phenomena of the glacial epoch
clear and intelligible. I then review the various suggested expla-
nations, and, taking up the two which alone seem tenable, I en-
deavor to determine the true principles of each. While adopt-
ing generally Mr. Croll's views as to the causes of the "glacial
epoch," I have introduced certain limitations and modifications.
1 have pointed out, with more precision than has, I believe,
hitherto been done, the very different effects on climate of water
in the liquid and in the solid state; and I have shown by a va-
riety of evidence that without high land there can be no per-
manent snow and ice. From these facts and principles, the very
important conclusion is reached that the alternate phases of pre-
cession— causing the winter of each hemisphere to be in aphelion
and perihelion each 10,500 years — would produce a complete
change of climate only where a country wsLspartially snow-clad ;
while, whenever a large area became almost wholly buried in
snow and ice, as was certainly the case with Northern Europe
during the glacial epoch, then the glacial conditions would be
continued, and perhaps even intensified, when the sun approached
nearest to the earth in winter, instead of there being at that
time, as Mr. CroU maintains, an almost perpetual spring. This
important result is supported by reference to the existing dif-
ferences between the climates of the Northern and Southern hem-
ispheres, and by what is known to have occurred during the last
494: ISLAND LIFE. [Part U.
glacial epoch ; and it is shown to be in complete harmony with
the geological evidence as to intei'glacial mild periods.
Discussing next the evidence for glacial epochs in earlier
times, it is shown that Mr. Croll's views are opposed by a vast
body of facts, and that the geological evidence leads irresistibly
to the conclusion that during a large portion of the Secondary
and Tertiary periods, uninterrupted warm climates prevailed in
the north temperate zone, and so far ameliorated the climate of
the arctic regions as to admit of the growth of a luxuriant veg-
etation in the highest latitudes yet explored. The geograph-
ical condition of the Northern Hemisphere at these periods is
then investigated, and it is shown to have been such as to admit
the warm tropical waters freely to penetrate the land, and to
reach the arctic seas by several channels; and, adopting Mr.
Croll's views as to the enormous quantity of heat that would
thus be conveyed northward, it is maintained that the mild
arctic climates are amply accounted for. With such favorable
geographical conditions, it is shown that changes of eccentric-
ity and of the phases of precession would have no other effect
than to cause greater differences of temperature between sum-
mer and winter; but wherever there was a considerable extent
of very lofty mountains the snow-line would be lowered, and,
the snow-collecting area being thus largely increased, a consider-
able amount of glaciation might result. Thus may be explained
the presence of enormous ice-borne rocks in Eocene and Mio-
cene times in Central Europe, while at the very same period
all the suri'ounding country enjoyed a tropical or subtropical
climate.
The general conclusion is thus reached that geographical con-
ditions are the primary causes of great changes of climate, and
that the radically different distribution of land and sea in the
iS^orthern and Southern hemispheres has generally led to great
diversity of climate in the arctic and antarctic regions. The form
and arrangement of the continents are shown to be such as to
favor the transfer of warm oceanic currents to the north far in
excess of those which move towards the south ; and whenever
these currents had free passage through the northern land-masses
to the polar area, a mild climate must have prevailed over the
Chap. XXIV. J SUMMARY AND CONCLUSION. 495
•
whole Northern Hemisphere. It is only in very recent times
that the great northern continents have become so completely
consolidated as they now are, thus shutting out the warm water
from their interiors, and rendering possible a wide-spread and
intense glacial epoch. But this great climatal change was act-
ually brought about by the high eccentricity which occurred
about 200,000 years ago ; and it is doubtful if a similar glacia-
tion in equally low latitudes could bo produced, by means of any
such geographical combinations as actually occur, without the
concurrence of a high eccentricity.
A survey of the present condition of the earth supports this
view; for, though we have enormous mountain-ranges in every
latitude, there is no glaciated country south of Greenland in
N. lat. 61^. But directly we go back a very short period, we
find the superficial evidences of glaciation to an enormous ex-
tent over thi*ee fourths of the globe. In the Alps and Pyrenees,
in the British Isles and Scandinavia, in Spain and the Atlas, in
the Caucasus and the Himalayas, in Eastern Noi*th America and
west of the Kocky Mountains, in the Andes, in the mountains
of Brazil, in South Africa, and in New Zealand, huge moraines
and other unmistakable ice-marks attest the universal descent
of the snow-line for several thousand feet below its present level.
If we reject the influence of high eccentricity as the cause of
this almost univei^sal glaciation, we must postulate a general ele-
vation of aU these mountains about the same time ; for the close
similarity in the state of preservation of the ice-marks, and the
known activity of denudation as a destroying agent, forbid the
idea that they belong to widely separated epochs. It has, in-
deed, been suggested that denudation alone has lowered these
mountains so much during the Quaternary epoch that they were
previously of sufficient height to account for the glaciation of
all of them, but this hardly needs refutation ; for it is clear that
denudation could not at the same time have removed some
thousands of feet of rock from many hundreds of square miles
of lofty snow-collecting plateaus, and yet have left moraines
and blocks, and even glacial striae, undisturbed and uneffaced on
the slopes and in the valleys of these same mountains.
The theory of geological climates set forth in this volume,
496 ISLAND LIFE. [Paiit If.
while founded on Mr. Croll's researches, differs from all that
have yet been made public, in clearly tracing out the compar-
ative influence of geographical and astronomical revolutions,
showing that, while the former have been the chief, if not the
exclusive, causes of the long-continued mild climates of the arc-
tic regions, the concurrence of the latter has been essential to the
production of glacial epochs in the temperate zones, as well as
of those local glaciations in low latitudes of which there is such
an abundance of evidence.
The next question discussed is that of geological time as
bearing on the development of the organic world. The periods
of time usually demanded by geologists have been very great,
and it was often assumed that there was no occasion to limit
them. But the theory of development demands far more ; for
the earliest fossiliferous rocks prove the existence of many and
varied forms of life which require unrecorded ages for their
development — ages probably far longer than those which have
elapsed from that period to the present day. The physicists,
however, deny that any such indefinitely long periods are avail-
able. The sun is ever losing heat far more rapidly than it can
be renewed from any known or conceivable source. The earth
is a cooling body, and must once have been too hot to support
life ; while the friction of the tides is checking the earth's rota-
tion, and this cannot have gone on indefinitely without making
our day much longer than it is. A limit is therefore placed to
the age of the habitable earth, and it has been thought that
the time so allowed is not sufticient for the long processes of
geological change and organic development. It is therefore
important to inquire whether these processes are either of them
so excessively slow as has been supposed, and I devote a chapter
to the inquir}'.
Gcolo«:ists have measured with some accuracv the maximum
thickness of all the known sedimentary rocks. The rate of
denudation has also been recently measured by a method which,
if not precise, at all events gives results of the right order of
magnitude, and which err on the side of being too slow rather
than too fast. If, then, the inaxivimn thickness of the Inowii
sedimentary rocks is taken to represent the average thickness
Chap. XXIV.] SUMMAKY AND CONCLUSION. 497
of aU the sedimentary rocks, and we also know the amount of
sediment carried to the sea or lakes, and the area over which
that sediment is spread, we have a means of calculating the
time required for the building-up of all the sedimentary rocks
of the geological system. I have here inquired how far the
above suppositions are correct, or on which side they probably
err ; and the conclusion arrived at is that the time required is
very much less than has hitherto been supposed.
Another estimate is afforded by the date of the last glacial
epoch as coincident with the last period of high eccentricity,
while the Alpine glaciation of the Miocene period is assumed to
have been caused by the next earlier phase of very high eccen-
tricity. Taking these as data, the proportionate change of the
species of mollusca affords a means of arriving at the whole
lapse of time represented by the fossiliferous rocks ; and these
two estimates agree in the order of their magnitudes.
It is then argued that the changes of climate every 10,500
years during the numerous periods of high eccentricity have
acted as a motive power in hastening on both geological and
biological change. By raising and lowering the snow-line in all
mountain-ranges, it has caused increased denudation ; while the
same changes have caused much migration and disturbance in
the organic world, and have thus tended to the more rapid modi-
fication of species. .The present epoch being a period of very
low eccentricity, the earth is in a phase of exceptional stability,
both physical and organic ; and it is from this period of excep-
tional stability that our notions of the very slow rate of change
have been derived.
The conclusion is, on the whole, that the periods allowed by
physicists are not only far in excess of such as are required for
geological and organic change, but that they allow ample margin
for a lapse of time anterior to the deposit of the earliest fossilif-
erous rocks several times longer than the time which has elapsed
since their deposit to the present day.
Having thus laid the foundation for a scientific interpretation
of the phenomena of distribution, we proceed to the Second Part
of our work — the discussion of a series of typical insular faunas
and fioras with a view to explain the interesting phenomena they
32
498 ISLAND LIFE. fPjLxrIL
present. Taking, first, two North Atlantic groups — the Azores
and Bermuda— it is shown how important an agent in the dis-
persal of most animals and plants is a stormy atmosphere. Al-
though 900 and 700 miles respectively from the nearest continents,
their productions are very largely identical with those of Earopo
and America; and, what is more important, fresh arrivals of
hirds, insects, and plants are now taking place almost annually.
These islands afford, therefore, test examples of the great dis-
persive powers of certain groups of organisms, and thus serve as
a basis on which to found our explanations of many anomalies
of distribution. Passing on to the Galapagos, we have a group less
distant from a continent and of larger area, yet, owing to special
conditions, of which the comparatively stormless equatorial at-
mosphere is the most important, exhibiting far more speciality
in its productions than the more distant Azores. Still, however,
its fauna and flora are as unmistakably derived from the Ameri-
can continent as those of the Azores are from the European.
We next take St. Helena and the Sandwich Islands, both won-
derfully isolated in the midst of vast oceans, and no longer ex-
hibiting in their productions an exclusive affinity to one conti-
nent. Here we have to recognize the results of immense an-
tiquity, and of those changes of geography, of climate, and in
the general distribution of organisms which we know have oc-
curred in former geological epochs, and w.hose causes and con-
sequences we have discussed in the First Part of our volume.
Tills concludes our review of the oceanic islands.
Coming now to continental islands, we consider first those of
most recent origin and offering the simplest phenomena; and
begin with the l>ritish Isles as affording the best example of very
recent and well-known continental islands. IJeviewing the in-
teresting past history of Britain, we show why it is comparative-
ly poor in species, and why this poverty is still greater in Ireland.
I>y a careful examination of its fauna and flora, it is then shown
that the British Isles are not so completely identical, biological-
ly, with the continent as has been supposed. A considerable
amount of speciality is shown to exist, and that this speciality is
real, and not apparent, is supported by the fact that small out-
lying islands, such as the Isle of Man, the Shetland Isles, Lundy
Chap. XXIV.] SUMMARY AND CONCLUSION. 499
Island, and the Isle of Wight, all possess certain species or va-
rieties not found elsewhere.
Sorneo and Java are next taken, as illustrations of tropical isl-
ands which may be not more ancient than Britain, but which,
owing to their much larger area, greater distance from the con-
tinent, and the extreme richness of the equatorial fauna and
flora, possess a large proportion of peculiar species, though these
are, in general, very closely allied to those of the adjacent parts
of Asia. The preliminary studies we have made enable ns to
afford a simpler and more definite interpretation of the peculiar
relations of Java to the continent and its differences from Bor-
neo and Sumatra than was given in my former work, " The
Geographical Distribution of Animals."
Japan and. Formosa are next taken, as examples of islands
which are decidedly somewhat more ancient than those pre-
viously considered, and which present a number of very inter-
esting phenomena, especially in their relations to each other,
and to remote rather than to adjacent parts of the Asiatic
continent.
We now pass to the group of ancient continental islands,
of which Madagascar is the most typical example. It is sur-
rounded by a number of smaller islands which may be termed
its satellites, since they partake of many of its peculiarities ;
though some of these, as the Comoros and Seychelles, may be
considered continental; while others, as Bourbon, Mauritius,
and Eodriguez, are decidedly oceanic. In order to nndei*stand
the peculiarities of the Madagascar fauna, we have to consider
the past history of the African and Asiatic continents, which it
is shown are such as to account for all the main peculiarities of
the fauna of these islands without having recourse to the hy-
pothesis of a now-submerged Lemurian continent. Considerable
evidence is further adduced to show that " Lemuria" is a myth,
since not only is its existence unnecessary, but it can be proved
that it would not explain the actual facts of distribution. The
origin of the interesting Mascarene wingless birds is discussed,
and the main peculiarities of the remar£:able flora of Madagascar
and the Mascarene Islands pointed out ; while it is shown that all
these phenomena are to be explained on the general principles
500 ISLAND LIFE. [Paw IL
of the permanence of the great oceans and the comparatively
slight fluctuations of the land area, and by taking acconnt of
established palseontological facts.
There remain two other islands, Celebes and New Zealand,
which are classed as '^ anomalous " — the one because it is alaiost
impossible to place it in any of the six zoological regions, or de-
termine whether it has ever been actually joined to a continent ;
the other because it combines the characteristics of continen-
tal and oceanic islands.
The peculiarities of the Celebesian fauna have already been
dwelt upon in several previous works, but they are so remarka-
ble and so unique that they cannot be omitted in a treatise on
" insular faunas ;" and here, as in the case of Borneo and Java,
fuller consideration and the application of the general principles
laid down in our First Part lead to a solution of the problem
at once more simple and more satisfactory than any which have
been previously proposed. I now look upon Celebes as an ont- /
lying portion of the great Asiatic continent of Miocene times,
which either by submergence or some other cause had lost the
greater portion of its animal inhabitants, and since then has re-
mained more or less completely isolated from every other land.
It has thus preserved a fragment of a very ancient fauna along
with a number of later types which have reached it from sur-
rounding islands by the ordinary means of dispersal. This suf-
ficiently explains all the peculiar affinities of its animals, though
the peculiar and distinctive characters of some of them remain
as mysterious as ever.
New Zealand is shown to be so completely continental in its
geological structure, and its numerous wingless birds so clearly
imply a former connection with some other land (as do its nu-
merous lizards and its remarkable reptile, the Ilattcria), that the
total absence of indigenous land mammalia was hardly to be ex-
pected. Some attention is therefore given to the curious ani-
mal which has been seen but never captured, and this is shown
to be probably identical with an animal referred to by Captain
Cook. The more accurate knowledge which has recently been
obtained of the sea-bottom around New Zealand enables us to
determine that the former connection of that island with Aus-
Chap. XXIV.] SUMMARY AND CONCLUSION. 601
tralia was towards the north, and this is found to agree well
with many of the peculiarities of its fauna.
The flora of New Zealand and that of Australia are now both
80 well known, and they present so many peculiarities and re-
lations of so anomalous a character, as to present, in Sir Joseph
Hooker's opinion, an almost insoluble problem. Much addition-
al information on the physical and geological history of these
two countries has, however, been obtained since the appearance
of Sir Joseph Hooker's works, and I therefore determined to
apply to them the same method of discussion and treatment
which has been usually successful with similar problems in the
case of animals. The fact above noted, that New Zealand was
connected with Australia in its northern, tropical portion only,
of itself affords a clew to one portion of the specialities of the
New Zealand flora — the presence of an unusual number of
tropical families and genera, while the temperate forms consist
mainly of species either identical with those found in Australia
or closely allied to them. But a still more important clew is
obtained in the geological structure of Australia itself, which is
shown to have been for long periods divided into an eastern
and a western island, in the latter of which the highly peculiar
flora of temperate Australia was developed. This is found to
explain with great exactness the remarkable absence from New
Zealand of all the most abundant and characteristic Australian
genera, both of plants and of animals, since these existed at that
time only in the western island ; while New Zealand was in con-
nection with the eastern island alone, and with the tropical por-
tion of it. From these geological and physical facts, and the
known powers of dispersal of plants, all the main features and
many of the detailed peculiarities of the New Zealand flora are
shown necessarily to result.
Our last chapter is devoted to a wider, and if possible more
interesting, subject — the origin of the European element in the
floras of New Zealand and Australia, and also in those of South
America and South Africa. This is so especially a botanical
question that it was with some diffidence I entered upon it ; yet
it arose so naturally from the study of the New Zealand and
Australian floras, and seemed to have so much light thrown
502 ISLAND LIFE. [Part II.
upon it by oar preliminary studies as to changes of climate and
the causes which have favored the distribution of plants, that I
felt my work would be incomplete without a consideration of
it. The subject will be so fresh in the reader's mind that a
complete summary of it is unnecessary. I venture to think,
however, that I have shown, not only the several routes by
which the northern plants have reached the various southern
lands, but have pointed out the special aids to their migration,
and the motive power which has urged them on.
In this discussion, if nowhere else, will be found a complete
justification of that lengthy investigation of the exact nature of
past changes of climate which to some readers may have seemed
unnecessary and unsuited to such a work as the present. With-
out the clear and definite conclusions arrived at by that discus-
sion, and those equally important views as to the permanence
of the great features of the earth's surface, and the wonderful
dispersive powers of plants which have been so frequently
brought before us in our studies of insular floras, I should not
have ventured to attack the wide and difficult problem of the
northern element in southern floras.
In concluding a work dealing with subjects which have oc-
cupied my attention for many years, I trust that the reader who
has followed me throughout will be imbued with the conviction
that ever presses upon myself, of the complete interdependence
of organic and inorganic nature. Xot only docs the marvellous
structure of each organized being involve the whole past history
of the cartli, but such apparently unimportant facts as the pres-
ence of certain types of plants or animals in one island rather
than in another are now shown to be dependent on the long
series of past geological changes; on those marvellous astro-
nomical revolutions which cause a periodic variation of terres-
trial climates; on the apparently fortuitous action of storms
and currents in the conveyance of germs ; and on the endlessly
varied actions and reactions of organized beings on each other.
And although these various causes are far too complex in their
combined action to enable us to follow them out in the case of
any one species, yet their broad results are clearly recognizable ;
and we are thus encouraged to study more completely every de-
Chap. XXIV.] SUMMARY AND CONCLUSION. 503
tail and every anomaly in the distribution of living things, in the
firm conviction that by so doing we shall obtain a fuller and
clearer insight into the course of nature, and with increased con-
fidence that the "mighty maze" of Being we see everywhere
around us is " not without a plan."
INDEX
INDEX.
Acacia, 176.
Acacia keterophifUa^ 406.
A, koa, 406.
Acaena in California, 486.
Accipiter Hawaii, 296.
Achatinellins, averaj^e range o^ 299.
uKgialitis Sanctce Helena, 288.
Africa, characteristic mammalia of, 381.
former isolation of, 383.
Africa and Madngascar, relations of, 883.
early history of, 384.
African highlands as aiding the migration
ofplants, 483, 484.
African reptiles absent from Madagascar,
382.
Aggressive power of the Scandinavian
flora, 471.
Air and water, properties of, in relation to
climate, 125.
AlectorcBtias ptUcherrimus, 395.
Allen, Mr. J. A., on variation, 55, 56.
Allied species occupy separate areas, 441.
Alpine plants, their advantages as colo-
nizers, 463.
Alternations of climate in Switzerland and
North America, 115.
palaeontological evidence of, 113.
Amazon, limitation of species by, 17, 18.
Amblyrhynchus crittatus, 265.
American genera of reptiles in Madagas-
car, 382.
Amphibia, dispersal of, 71.
of the Seychelles, 395, 396.
introduced, of Mauritius, 402.
of New Zealand, 445, 446.
Amphioxu;*, 61.
Amydrus Tristramii, restricted range of^
15.
Anas WyviUiana, 296.
Ancient continental islands, 234, 376.
Ancient glacial epochs, 161.
what evidence of, may be expected,
167.
Ancient groups in Madagascar, 385.
Andersson, N. J., on the flora of the Ga-
lapagos, 272.
Andes, migration of plants along the, 480.
Andromeda, 177.
Angracum seaquipedale, 404.
Animal life, effects of gUcial epoch on, 1 1 1 .
of Formosa, 366.
Anoa depressicornts, 419.
Antarctic continent as a means of plant-
dispersion, 481.
Antarctic islands with perpetual snow,
128,129.
Antelopes, overlapping genera of, 28.
Antiquity of Hawaiian fauna and flora,
304.
of land shells, 74.
of New Zealand, 485.
of plants as affecting their dispersal,
77.
Apera arundinacea, 463.
Apium graveolens in New Zealand, 475.
Apteryx, species of, 439.
Arabis hirsuta on railway arch, 474.
Archaic forms still existing, 218.
Arctic and antarctic regions, contrasts of,
130.
Arctic current, effects of a stoppage of,
143.
Arctic plants in the Southern Hemisphere,
469.
Arctic regions, mild climates of, 173.
recent interglacial mild period in, 173.
Arctic warm climates of Secondary and
Palaeozoic times, 192.
Areas of distribution, 13.
separate and overlapping, 17.
Ascension, former climate and productions
of, 286.
Astronomical and geographical causes,
comparative effects of, on climate,
197.
Astronomical causes of change of climate*
120.
of glaciation, 133, 134.
508
INDEX.
Atlantic ules, peculiar mosses of, 837.
Atlantosaurus, the largest land-animni, 98.
AtHplex patula on a railway bank, 474.
Auchenin, 2G.
Austen, Mr. Godwin, on littoral shells in
deep water, 312.
Anstrnlia, two sets of northern plants in,
483.
South European plants in, 483.
Australia and South Africa, supposed con-
nection of, 484, 485.
Australian birds absent from New Zea-
land, 445.
Australian flora, general features of, 453.
richest in temperate zone, 453.
recent andderivative in the tropics, 454.
its southeastern and southwestern di-
visions, 454, 455.
Sir Joseph Hooker on, 455.
geological explanation of, 455, 456.
its presence in New Zealand, 459.
natural orders of, wanting in New
Zealand, 451.
Australian genera of plants in India, 486.
Australian orchidese in China, 486.
Australian plants absent from New Zea-
land, 450-452.
none in north temperate zone, 398.
running wild in Neilgherry moun-
tains, 487.
Australian region, definition of, 44.
ranmmals and birds of, 45.
Australian seeds scattered in New Zea-
land, 467.
Aylward, Captain, on glaciation of South
Africa, 154, 155.
Azorean bird fauna, origin of, 237, 238.
Azorean fauna and flora, deductions from,
248, 249.
Azorean plants, facilities for the dispersal
of, 247.
Azores, 235, 236.
absence from, of large- fruited trees or
shrubs, 247.
zoological features of, 236.
birds of, 237.
insects of, 240.
beetles of, 241.
land shells of, 243.
flom of, 244.
Azores and New Zealand, identical plants
ill both, 472.
Bahirusa alfurus^ 419.
Badgers, 40.
Bahamas contrasted with Florida, 5.
Baker, Mr., on flora of Mauritius and the
Seychelles, 404.
Bali and Lombok, contrasts of, 4.
Banca, peculiar species of, 354.
Barbarea precox on railway bank, 478.
Barn-owl, wide range of, 15.
BaiTiers to dispersal, 69.
Bats in Bermuda, 255.
Bears of Europe and America, 14.
Beaver of Europe and America, 14.
Beetles of the Azores, 241.
remote affinities of some of, 242.
Beetles of the Galapagos, 269.
of St. Helena, 281.
of the Sandwich Islands, 800.
peculiar British species of, 327.
Bell-birds, distribution of, 22, 28.
Bennett, Mr. A., on the vegetation of rail-
way banks, 482.
Bentham, Mr., on the Compositas of the
Galapagos, 273.
on the CompositflB of St Helena, 290.
291.
on the Mascarene Compositse, 408.
on Sandwich Island Compositae, 303.
Bermuda, 249.
zoology of, 252, 258.
i-eptiles of, 252.
birds of, 253.
insects of, 256.
land moUusca of, 256.
flora of, 257.
red clay of, 252.
soundings around, 250, 251.
Bermuda and Azores, comparison of bird
faunas of, 254.
Bernicla SandvichensiSy 206.
Biological causes which determine distii-
bution, 491.
Biological features of Madagascar, 380,
381.
Birchall, Mr. Edwin, on Isle of Man Lepi-
doptera, 326.
Birds as plant-dispersers, 76.
as seed-carriers, 245, 246.
common to Great Britain and Japan,
362.
common to India and Japan, 364.
dispersal of, 70, 71.
of the Azores, 237.
of Bermuda, 253.
of Bermuda and Azores compared,
254.
of the Galapagos, 266.
of the Sandwich Islands, 296.
peculiar to Britain, 315.
of Borneo, 346.
of Java, 3."il.
of the rhilippines, 355,
of Japan, 361, 362.
INDEX.
509
Birds pecaliar to Japan, 363.
peculiar to Formosa, 369.
common to Formosa and India or
Malaya, 470.
of Madagascar, and their teachings,
387.
of Comoro Islands, 393.
of the Seychelles, 394.
of the Mascarene islands, 400.
of islands east and west of Celebes,
417.
of Celebes, 420.
peculiar to Celebes, 421.
of New Zealand, 438, 439, 445.
ranges of, 1 5.
specific range of, 1 5.
wingless, of New Zealand, 439.
Blackburn, Mr. T., on the beetles of the
Sandwich Islands, 800.
Blakiston and Fryer on birds of Japan,
362.
Blanchard, M. Emile, on flora of Mada-
gascar, 404.
Bland, Mr., on land shells of Bermuda,
266.
Blanford, Mr. W. T., on small effect of
marine denudation, 215.
Blocks, travelled and perched, 104.
Blue magpies, range of, 15.
Borneo, geology of, 344.
mammalia of, 344, 345.
birds of, 846-348.
insects and land shells of, 348, 349.
affinities of fauna of, 349.
Borneo and Asia, resemblance of, 6.
Borneo and Java, 342.
Boulder-beds of the carboniferous forma-
tion, 192.
Boulder clays of east of England, 112.
Bovidse, 28.
Brady, Mr. H. B., on habitat of Globige-
rin«, 87, 88.
Britain, probable climate of, with winter
in aphelion, 148, 149.
British birds, range of, 33-37.
British Columbia, interglacial warm pe-
riods in, 1 16.
British fauna and flora, pecoliarities of,
339, 340.
British Isles, recent changes in, 308.
proofs of former elevation of, 310.
submerged forests of, 310.
buried river channels of, 312.
Inst union of, with continent, 813.
why poor in species, 313, 314.
peculiar birds of, 815.
fresh-water fishes of, 316.
peculiar insects of, 320.
British Isles, peculiar Lepidoptera of, 322-
824.
peculiar Coleoptera of, 327-329.
peculiar Trichoptera of, 331, 332.
peculiar land and fresh-water shells
of, 332.
peculiarities of the flora of, 333.
peculiar mosses and Uepaticse of, 335,
336.
British mammals as indicating a zoolog-
ical region, 31, 32.
Buried river channels, 312.
Buteo solitarius, 296.
Butterflies of Celebes, peculiar shape of,
425.
Butterflies, peculiar British, 322-324.
Caddis-flies peculiar to Britain, 331.
Csecilia, species of, in the Seychelles,
398.
wide distribution of, 397.
Cieciliadfe, 27.
Callithea Leprieuri, 18.
Callithea sapphira, 18.
Camels as destroyers of vegetation, 280.
Camels, former wide distribution of, 885.
Camelus, 17, 26.
Campanula Vidalii^ 248.
Canis, 16, 25.
Carabus, 41.
Carboniferous boulder-beds, 192.
Carboniferous warm arctic climate, 193.
Carduus marianus in New Zealand, 475.
Camivora in Madagascar, 382.
Carpenter, Dr., on habitat of Globigerins,
88.
Carpenter, Mr. Edward, on Mars and gla-
cial periods, 156.
Carjtodacus purjrtureus and P.Cali/amicuSf
65.
Castor, 17.
Casuarina, 1 76.
Casuarina in India, 486.
Cause of extinction, 60, 61.
Caves of Glamorganshire, 31 1 .
Cebibae, overlapping genera of, 28.
Celebes, physical features of, 414.
islands around, 416.
zoology of, 418.
derivation of mammals of, 419.
birdsof, 420, 421.
not a continental island, 423.
insect peculiarities of, 424.
Himalayan types in, 425.
peculiarity of butterflies of, 425.
list of land birds of, 428-433.
CentetidsB, 26.
formerly inhabited Europe, 884.
510
INDEX.
Central America, oO, 51.
Ceratodus, or mud-fish, Sd.
Cervus, 17, 25.
Chalk a supposed oceanic formation, 84,
85.
analysis of, 87.
at Oahu, analysis of, 86.
deposited in a shallow sea, 90.
Qf Faxoe an ancient coral reef, 90.
modem formation of, 90, 91.
supposed oceanic origin of, erroneous,
92.
Chalk formation, land plants found in, 89.
Chalk mollusca indicative of shallow wa-
ter, 88.
Chalk sea, extent of, in Europe, 89.
Challenger ridge in the Atlantic, 9G.
soundings and shore-deposits, 82.
Chameleons veiy abundant in Madagas-
car, 395.
Chamois, distribution of, 13.
Changes of land and sea, 79.
Chasmorhynchus, distribution of, 23.
CIdlomentu lunata^ 284.
C,nudicoUU,2X
C, tricaruncuiatuSy 23.
C, variegatuSf 23.
Chinchillas, 25.
ChrysochloridoB, 28.
Cicindela, 17.
CicindcIidoB common to South America
and Madagascar, 27.
Climatal change, its essentia] principle re-
stated, 150.
Climntal changes, 101.
as modifying organisms, 21G, 218,
219.
Climate affected by arrangement of the
great continents, 195.
astronomical causes of changes of,
120.
causes of mild arctic, 181.
changes of, during Tertiary and Sec-
ondary Periods, 194.
changes of, as affecting migration of
plants, 477.
nature of changes of, caused by high
eccentricity, 220.
exceptional stability of the present,
220, 221.
of Britain with winter in aphelion,
148, 149.
of Tertiary Period in Europe and
North America, 1G9.
of the Secondary and Paleozoic
epochs, 100-192.
properties of snow and ice in relation
to, 125.
Climates of Tertiary and-SecoDdary Peri-
ods, 193.
Clouds cut off the sun's heat, 138.
Coal in Sumatra, 353.
Coast-line of globe, extent of, 211.
Cochoa, distribution of, 24.
Cold alone does not cause glaciation, 128.
how it can be stored up, 126.
Coleoptera of the Azores, 241.
of Sl Helena, 281.
of the Sandwich Islands, 300.
peculiar British species of, 327.
Comoro Islands, 392.
mammals and birds of, 393.
Composiue of the Galapagos, 273.
of St. Helena, 290.
of the Sandwich Islands, 808.
of the Mascarene Islands, 409.
species often have restricted ranges,
4G4.
Conclusions on the New Zealand flors,
4G6.
Contemporaneous formation of Lower
Greensand and Wealden, 210.
Continental conditions throughout geo>
logical time, 91-95.
changes and animal distribution, 97.
extensions will not explain anoma-
lous facts of distribution, 412.
Continental islands, 231.
of recent origin, 307.
general remarks on i*ecent, 373.
Continental period, date of, 313.
Continents, movements of, 83, 81.
permanence of, 92.
general stability of, 9G, 97, 99.
geological development of, 19G.
Continuity of land, 70.
of now isolated groups, proof of,
G7.
Cook, Captain, on a native quadruped in
New Zei\land, 438.
Coi)e, Professor, on the Bermuda lizard,
252, 253.
Coracias Ttmminckii^ 425.
Corvus, IG.
Cossouidic, in St. Helena, 282.
Cretaceous deposits in North Australia,
454, 45G.
Cretaceous Hora of Greenland, 177.
CroU, Dr. James, on antarctic icebergs,
i;;o.
on winter temperature of Britain in
glacial epoch, 134.
on diversion of Gulf Stream during
the glacial epoch, ISG.
on loss of heat by clouds and fogs,
138.
INDEX.
511
CroU, Dr. James, on geographical causes
OS affecting climate, 140.
on ancient glacial epochs, 162.
on universality of glacial markings in
Scotland, 165.
on mild climates of arctic regions,
173.
on ocean currents, 181, 195.
on age of the earth, 203.
on mean thickness of sedimentary
rocks, 209.
on small amount of marine denuda-
tion, 214.
on buried river channels, 812.
Ctenodus, 66.
Cyanopica, distribution of, 23.
Cyanopica Cooki, restricted range of, 15,
23.
C cyanus, 23.
Cynomthectts nigrescensy 419.
Dacelo, 45.
Dana on continental npheavals, 84.
on chalk in the Sandwich Islands, 86.
on elevation of land causing the gla-
cial epoch, 144, 145.
on elevation of Western America,
185.
on the development of Continents,
196.
on shore deposits, 212.
on life extermination by cold epochs,
219.
Darwin, on the permanence of oceans, 95.
on cloudy sky of antarctic regions,
138, 139.
on glaciers of the Southern Andes,
140.
on geological time, 201.
on complex relations of organisms,
216.
on seeds carried by birds, 246.
on natural history of the Keeling Isl-
ands, 270.
on cultivated plants not running
wild, 467.
Darwin's experiment on Helix pomatioj
74.
experiments on seed-dispersal, 245.
theory of formation of atolls, 390.
De Candoiie on dispersal of seeds, 76.
Deep-sea deposits, 208.
Delphinium Ajacis on a railway bank, 474.
Dendrceco, 18.
Dendraca coronata, variation of, 56,
D. ccertUeaf 18.
D. discolor^ 18.
U, Dominica f 18.
Dendrophidxe, 27.
Denudation and deposition as a measure
of time, 203.
destroys the evidences of glaciation,
164.
in river basins, measurement of, 204.
marine, as compared with subaeiial,
214.
Deposition of sediments, how to estimate
the average, 210, 211.
Deserts, cause of high temperature of,
126.
Diagram of eccentricity and precession,
122.
of eccentiicity for three million years,
163.
Dididae, how exterminated, 400.
Didunculus, keeled sternum of, 401.
Diospyros, 177.
Diplotaxis muralis on railway bonks,
473.
Dipnoi, discontinuity of, 66.
Diptems, 66.
Discontinuity a proof of antiquity, 66.
among North American birds, 64.
Discontinuous areas, 62.
why rare, 62.
Discontinuous generic areas, 23.
Dispersal of animals, 68.
of Azorean plants, facilities for, 247.
of land animals, how effected, 72.
Dispersal of seeds by wind, 75, 76.
by birds, 76.
by ocean currents, 77.
along mountain-chains, 77.
Distribution, changes of, shown by extinct
animals, 97, 98.
how to explain anomalies of, 885.
Dobson, Mr., on bats of Japan, 360.
on the affinities of Mystacina tubev'
ctUata, 437.
Dodo, the, 400.
aborted wings of, 401.
Drontheim mountains, peculiar mosses of,
337.
Dryiophidoc, 27.
Dumeril, Professor, on lizards of Bourbon,
399.
Duncan, Professor P. M., on ancient sea
of Central Australia, 465.
Early history of New Zealand, 446, 447.
ICarth's age, 200.
East and West Australian floras, geologi-
cal explanation of, 455, 456.
East Asian birds, range of, 37.
Eccentricity a test of rival theories of
climate, 163.
512
INDEX.
Eccentricity, high, its effects on warm and
cold climates, 189, 190.
variations of, during three million
years, 1G2.
Eccentricity and precession, diagram of,
122.
Echidna, 29.
l^khimyidie, 26.
Elevation of North America during gla-
cial period, 147.
causing diversion of Gulf Stream,
147.
Emberiza schamiclus, discontinuity of, 63.
K. pcuserinoy range of, 63.
£, pyrrhulina, 63.
Endemic genera of plants in Mauritius,
etc., 406.
in New Zealand, 485.
English plants in St. Helena, 281.
Environment, change of, as modifying or-
ganisms, 215.
Eriocaulon septangtdaref 334.
Ethiopian region, definition of, 41.
birds of, 42.
Ettinghausen, Dr., on Australian plants in
England, 478.
Eucalyptus, 1 76.
in Eocene of Sheppey, 478.
Eucalyptus and Acacia, why not in New
Zealand, 467.
Eupetes, distribution of, 24.
Europe, Asia, etc., as zoological terms,
30.
European birds, rnnjje of, 15.
in Bermuda, 2r»r>.
European occupation, effects of, in St. He-
lena, 278.
European plants in New Zealand, 400.
in Chili and Fuegia, 480.
Everett, Mr., on raised coral reefs in the
Philippines, 355.
Evolution necessitates continuity, 67.
Explanation of peculiarities of the fauna
ofCelebcs, 422, 42H.
Extinct animals showing changes of dis-
tribution. 1)7, 98.
Extinct birds of the Mascarene Islands,
400.
of New Zealand, 430.
Extinction caused by glacial epoch, 110,
117.
Families, restricted areas of, 28.
distribution and antiquity of, 05.
Fauna and flora, peculiarities of British,
330, 340.
Fauna of Borneo, affinities of, 349.
of Javo, 850.
Fauna of Java and Asia compAred, 351,
352.
Faunas of Hainan, Formosa, and Japan
compared, 372.
Felis, 16, 25.
Ferns, abundance of, in Mascarene flora,
408.
Ficus, 177.
Fire-weed, the, of ISismania, 473.
Fisher, Rev. O., on temperatare of qiace,
124.
Fishes, dispersal of, 71 .
peculiar British, 316.
cause of great speciality in, 318.
mode of migration of fresh - water,
319.
fresh-water, of New Zealand, 446.
Floating islands and the dispersal of ani-
mals, 69, 70.
Flora of New Zealand, 449.
very poor, 450.
its resemblance to the An8tralian,451.
its differences from the Australian,
451,452.
origin of Australian element in, 459.
tropical character of, explained, 461,
462.
summary and conclusion on, 466.
Flora of the Azores, 244.
of Bermuda, 257.
of the Galapagos, 272.
of St. Helena, 289.
of the Sandwich Islands, 300.
of the Sandwich Islands, peculiar feat-
ures of, 301.
peculiarities of the British, 333.
of Madagascar and the Mascarene
Islands, 403.
of Madagascar and South Africa al-
lied, 408.
Floras of New Zealand and Australia,
summary of conclusion as to, 501.
Florida and Canada, resemblances of, 5,
and the Bahamas, contrasts of, 5.
! Fogs cut otf the sun's heat in glaciated
countries, 138.
Forbes, Mr. D., analysis of chalk, 87.
Forests, submerged, 310.
Former continuity of scattered groups,
67.
Formosa, 305.
phvsical features of, 366.
animal life of, 300,307.
list of mammalia of, 367, 368.
list of land birds peculiar to, 369-371.
Freezing water liberates low-grade heat,
138.
Fresh-water deposits, extent of, 92, 98.
INDEX.
513
Frasli- water fishes of the Seychelles, 898.
Tresb-water organisms absent in St. He-
lena, 288.
snnil peculiar to Ireland, 332.
Frogs of the Seychelles, 39(>.
of New Zealand, 446.
Fnegia, European plants in, 480.
Fulica alai, 296.
Galapagos, absence of manimaliu and am-
phibia from, 263, 264.
reptiles of, 264.
birds of, 266.
insects of, 269.
land shells of, 269.
flora of, 272.
Galapagos Islands, 261.
and Azores contrasted, 274, 275.
Galbula cyaneicollis, 18.
G, rufoviridin^ 1 8.
G. viridis, 17.
Galeopithecus, 61.
Gallinula Sandnr.hetms^ 296.
Gardner, Mr. J. S., on Tertiaty changes
of climate, 194.
Garmlus, distribution of species of, 20.
Garrutus atvicapil/us, 2 1 .
G, btspectdaris, 21.
^;.2?ranrf/i, 21,22.
G. cervicalis, 20.
G. ffiandarim, 20, 22, 64.
G, hyrcanus, 21.
G, Joponicus, 21, 64.
G, Krynicki, 2 1 .
G, lanceolatu8,2\,
G, Lidthi, 22.
G. Sinensis^ 21.
(r, taivanuSf 2 1 .
Geikie, Dr. Jumes, on interglacial depos-
its, 116.
on age of buried river channels,
312.
Prof. A., on stratified rocks being
found near shores, 82, 83.
on formation of chalk iu shallow wa-
ter, 92.
on permanence of continents, 99.
on variation in rate of denudation,
165.
on the rate of denudation, 204.
on small amount of marine denuda-
tion, 216.
Genera, extent of, 17.
origin of, 59.
rise and dcc^iy of, 6 1 .
Generic areas, 16.
Generic and family distribution, 25.
Genus, defined and illustrated, 15, 16.
33
Geographical change as a cause of glacia-
tion, 141.
Geographical changes, influence of, on
climate, 143, 144.
effect of, on arctic climates, 183.
of Java and Borneo, 353.
as modifying organisms, 217.
Geological change, probably quicker in
remote times, 212, 213.
Geological changes as aiding the migra-
tion of plants, 479.
Geological climates and geographical con-
ditions, 194, 195.
as affecting distribution, 482.
summary of causes of, 483.
Geological time, 200.
value of the estimate of, 214.
measurement of, 222.
summary of views on, 496.
Geology of Borneo, 344.
of Madagascar, 377.
of Celebes, 414.
of New Zealand, 435.
of Australia, 456, 457.
Geomalacus macutosus^ 332.
Glacial climate not local, 1 10.
deposits of Scotland, 107.
Glacial epoch, proofs of, 101, 102.
effects of, on animal life. 111.
alternations of climate during, 112.
as causing; migi*ation and extinction,
116, 117.
causes of, 119.
the essentials to the production of,
128.
probable date of the, 152, 153.
and the climax of continental devel-
opment, 19().
date of last, 222.
Glacial phenomena in North America,
110.
Glaciation. summary of chief causes of,
137.
:n Northern Hemisphere, the only
efficient cause of, 140.
of New Zealand and South Africa,
la«>.
local, due to high eccentricity, 197.
wide-spread in recent times, 495.
was greatest where rainfall is now
greatest, 132.
Gleichenia in Greenland, 1 77.
Globigerina ooze, analysis of, 87.
in relation to chalk, 85.
Globigerinie, where found, 87, 88.
Glyptostrobus, 1 77.
Goats, destructiveness of, in St. Helena,
280.
514
INDEX.
Godenia, 176.
Godman, Mr., on birds reaching the Azores,
236.
Great Britnin and Japan, birds common
to, 362.
Greene, Dr. J. Beav, on chameleons in
Bourbon and Mauritius, 3t)'J.
Greenland, loss of sun-hcnt bv ciuuds in,
139.
an anomaly in the Northern Hemi-
sphere, 146.
Miocene flora of, 175.
Cretaceous flora of, 1 77.
flora of ice-surrounded rocks of, 482.
Grinnell Land, fossil flora of, 175.
Guernsey, peculiar caddis-fly in, 331.
Gulick, llev. J. T., on Achatinellinie, 299.
Giinther, Dr., on peculiar British lishes,
317.
on lizards in the London Docks, 395.
Ilaast, Dr., on otter-like mammal in New
Zealand, 438.
on kauii-trce in Cretaceous beds of
New Zealand, 4.VJ.
llabitability of globe due to disproportion
of land and water, 198, 199.
Haplothorax Burchellii, 283.
llartlaub. Dr. , on ** Lemuria," 387, 402.
JIatteria punctata, 446.
llaughtoii. Professor, on heat carried by
ocean ciirrcnt»», 18r>.
comparison of Miocene and existing
climates l)y. 187.
on ge(il()gical lime, 201, 212.
on tliickfiess of sedimeiitarv rocks,
208.
Hawaiian fauna and flora, nnticpiitv of,
304.
Heat a!i(l cold, how dispersed or stored
np, 12(;.
cut oft' by cloud and fop:**, 138.
recpiired to melt snow, 127.
evolved bv frozen water, its nature
and eftects, 137, 138.
Hector, Dr., on ancient flora of New Zea-
huid, 4r»I).
on Triassic and Jurassic flora of New
Zealand, 41)*.
Heer, rrofessor, on chalk sea in Central ,
Enrope, 81).
Hclianthemnm Jircwen\ I'M).
lleliodns, (»(».
Helix, 17.
Hemiptera of St. Helena, 287.
llcpaticii', peculiar Hritish, 33('.
no!i Kuropean genera of, in Britain,
Hesperomys, 25.
Hesperornis allied to ostriches, 443.
Hieracium iricum, 333.
High land essential to the prodactlou of
a glacial epoch, 128.
Ilimahivan birds and insects in Celebes,
425.
Hippopotamns in Yorkshire as proving a
mild cHmate, 113-115.
Himndo, 25.
Hochstetter on the aquatic mammal of
New Zealand, 438.
Hooker, Sir Joseph, on the Galapagos
flora, 272.
on afiinities of St. Helena plants, 289.
on the flora of New Zeahmd, 449.
on proportion of temperate and trop-
ical Australian floras, 453.
on current of vegetation from north
to soutli, 470.
on supposed occurrence of Australian
plants in England in the Tertiary
period, 478.
Humming-birds, restricted ranges of, 15.
Hutton, Captain, on Struthious birds of
New Zealand, 441.
Huxlev, Professor, on geological time,
*20l.
on European origin of African ani-
mals, 383.
Hyalina Dermudennisj 256.
Ii. circun{firmata, 256.
//. discrepanSy 256.
llyomoschns, 26.
llyracoidea, restricted range of, 29.
Ice-action, what evidences of, during the
Tertiary jKjriod, 169.
indications of ancient, 101.
Ice-borne rocks, a lest of a glacial epoch,
168.
in Miocene of Northern Italy, 169.
in l"'oeene of Alps, 170.
in Eocene of Carpathians and Apen-
nines, 170.
absence of, in English and North
American Teniaries, 172.
Ice-cap, why improbable or im])Ossible,
153.'
Iceland a continental island, 413.
Icteriilii?, 4 7.
Ignanichv, 48.
Indian birds in Formosa, 371.
Indian genera of plants in Australia, 454.
Indian Ocean as u soince of heat in Ter-
tiary times, 183, 184.
Indicator, distribution of, 25.
Insectivora in Madagascar, 381.
INDEX.
615
Inscctii, dispersiil of, 72, 73.
of the Miocene period, 75.
restriction of range of, 75.
of the Azores, 240.
of Bermuda, 256.
of the Galapagos, 2G9.
of the Sandwich Islands, 300.
peculiar British, 820.
of Celebes, peculiarities of, 424.
Insular faunas, summary of conclusions as
to, 498, 501.
luterglacial climates never very warm, 1 51.
periods and their probable character,
145.
periods will not occur during an epoch
of extreme glacintion, 147.
warm periods on the continent and
North America, 1 1 5.
Ireland, peculiar fishes of, 316, 818.
plants of, not found in Great Britain,
834.
poverty of, in reptiles, 313.
]x)verty of, in plants, 315.
Isatii tinctoria on railway bank, 478.
Islands, classification of, 230.
importance of, in study of distribu-
tion, 229.
remote, how stocked with plants and
animals, 248.
submerged between Madagascar and
India, 389.
Ible of Man, peculiarities of Lepidopteni
of. 326.
Isle of Wight, peculiar beetle of, 830.
Italian spaiTow, restricted range of, 15.
Ithaginis, 26.
Japan, zoological features of, 359.
mammalia of, 359.
birds of, 362.
birds peculiar to, 863.
Jiipan and Formosa, 357.
Japan birds in distant areas, 364.
Java and Borneo, past changes of, 353.
Java, fauna of, 350.
Asiatic species in, 351, 852.
past history of, 858.
Jays, distribution of species of, 20.
of Europe and Japan, 64.
Jeftrey;<,Dr. Gwyn, on shallow-water mol-
lusca in chalk, 88.
on fossil shallow-water shells in deep
water, 313.
Jones, Mr., on red clay of Bermuda,
256.
on migration of birds to Bermuda,
265.
on vegetation of the Bermudas, 257.
Juan Fernandez, flora and fauna of, 271,
272.
Judd, Prof. J. W., on absence of glacia-
tion in East Euroj^e, 132.
on glaciation of the Alps produced by
elevation, 171.
Juniperus Barbadensisy 258.
Jura, travelled blocks on, 104.
Jurassic warm arctic climate, 192.
Keeling Islands, animals of, 270.
Kirk, Mr. T., on temporary introduced
plants, 474, 476.
Knowledge of various kinds required for
study of geographical distribution,
7,9.
Tjapopus ScoticuSf 815.
Land and sea, changes of, 79.
how changes of, aflfect climate, 14 1 ,
142.
Land and water, disproportion of, renders
globe habitable, 199.
Land as a barrier to ocean currents, 1 43.
Land birds of Celebes, list of, 428-483.
Land connection, how far necessary to dis-
persul of mammals, 70.
Land shells, great antiquity of. 74.
universal distribution of, 75.
causes favoring the abundance of, 7.5.
of the Azores, 243.
of Bermuda, 256.
of the Galapagos, 270.
of St. Helena, 287.
of the Sandwich Islands, 298.
of the Sevchelles, 398.
LttwuB Canariensis^ 247.
Leguat on the Solitaire, 400.
Lcguminoste, abundance of, in Australia,
452.
''Lemuria," a supposed submerged conti-
nent, 287-292.
Lemurs in Madagascar, 881.
leopard, enormous range of, 1 4.
Lcpidoptera, list of peculiar British, 322-
324.
of the Isle of Man, 826.
Lepidosiren, 61.
Lepidosirenparadoxa^ and L, annecten8,(jG.
LepidostcmidiB, 27.
Limestone as indicating change of sea and
land, 81.
Limncea invoiuta, 882.
Linaria purpurea on railway bank, 478,
474.
TAopelma Hochstetterif 446.
Liotrichida*, 28.
List of the land birds of Celebes, 420.
516
INDEX.
Lizard peculiar to the Mascarcne Islands,
403.
IJzai'ds, local variation of color of, 39C.
of New Zeiitnnd, 44G.
of the Gahipngos, 2(>r>.
Lobeliaco;, abundance of, iu the Sandwich
Islands, 302.
Locality of a species, importance of, 12.
jAtddiijesia mirahilis, rarity of, 1(>.
Ijord, Mr., on species of Urotriclius, 360.
Low-grade and Iiigh-grade heat, 138.
Lowlands nowhere covered witli perpetu-
al snow, 128, 121).
Lundy Island, peculiar beetles of, 330.
Lyell, Sir Charles, on permanence of con-
tinents, 79, 80.
on calcareous mud, 87.
on the distribution of chalk, 88.
on geographical causes as moditying
climate, 141.
on estimate of geological time, 200.
on classification of scdimentarv rocks,
20G.
Lynxes, 40.
McLachlan, Mr., on peculiar British cad-
dis-flies, 322, 331.
Madagascar, physical features of, 377.
former condition of, 379.
biological features of, 380.
mammalia of, 381.
• reptiles of, 382.
relation of, to Africa, 383.
eai ly history of, 384.
birds of, in relation to *'Lemuria,"
387.
conclusion on fauna and flora of,
409, 410.
great antiquity of, 400.
Madagascar and Africa, contrast of, C.
relations of, 383.
Maillard on animals of Bourbon, 390.
Malaiy Islands, local peculiarities of flora
in, 178.
past history of, 3r»n.
Malayan birds in Formosa, 371, 372.
Mammalia of Kast Asia, range of, 32.
of North Africa, range of, 33.
of Britain, poverty of, 314.
of IJornco, 344, 34'*.
of .lava. 3.'»().
of the Philippines, 355.
of Japan, 359.
of Formosa, 307, 3G8.
common to Formosa and India, 309.
of Celebes, whence derived, 420.
of Comoro Islands, 393.
of Celebes, 419.
Mammalia of Madagascar, 381.
of New Zealand, 436.
Mann, Horace, on the flora of the Sand-
wich Islands, 300.
Maori legend of origin of the forest-rat,
437.
Maoris, their aceonnts of the moa. 440.
Map of the old Rhone glacier, 105.
of the Azores, 235.
of Bermuda, 250.
of the Galapagos, 262, 263.
of South Atlantic Ocean, 277.
of the Sandwich Islands, 294.
of the North Paciflc with its sub-
merged banks, 295.
of British Isles and the 100-fatliom
bank, 309.
of Borneo and Java, 343.
of Japan and Formosa, 358.
physicid, of Madagascar, 378.
of the Madagascar group, 380.
of the Indian Ocean, 389.
of Celebes, 4 1 5.
of sea-bottom around New Zealand,
435.
of Australia in Cretaceous period, 458.
Maps of North and South polar regions,
131.
Marcou, Professor Jules, on the Pliocene
and glacial epochs, 223.
Marmot, range of, 14.
Mars as illustrating glacial theories, 156,
159.
no true ice-cap on, 157.
Marsh, Prof. O. C, on the Atlantosaurus,
93.
on llesperornis, 443.
Marsh, Mr., on camels as desert-makers,
280.
Marsupials, range of, 20.
Mascarcne flora, fragtncntnrv character of,
407.
abundance of ferns in, 408.
Mascarene Islands, 302, 402.
Mascarcne plants, curious relations of, 405.
endemic genera of, 400.
Mainitius, Bourbon, and Hodriguez, 398.
Measurements of geological time, 223.
agreement of various estimates of,
concluding remarks on, 224, 225.
Medicaijo sativn in New Zealand, 475.
.Megahcinidic, 27.
Meleagris, 48.
A\fe/lfotus vnhjnris on railway banks, 473.
Meli|)hagi(l:c, 45.
Mclliss, Mr., on the early history of St.
Helena. 279.
INDEX
517
Melospiza melodia^ vnriution of, 5G.
Merrcotheriura, 117.
Meteorological causes as intensifying gla-
ciation, 13.5, 13G.
Migration caused liy glacial epoch, 1 1 6, 1 1 7.
of birds to Bermuda, 251.
of plants from north to south, 472.
uf plants and alterations of snow-
line, 47G.
of plants due to changes of climate,
477.
of plants from north to south, long
continued, 477, 478.
of plants aided bjr geological changes,
479.
of plants by way of Himalayas and
South Asia, 482, 483.
of plants by way of the Andes, 480.
of plants through Africa, 483, 484.
Mild arctic climates, stratigraphical evi-
dence of, 178, 179.
causes of, 181.
dependent on geographical changes,
182.
effects of high eccentricity on. 189.
summary of causes of, 491.
Miocene arctic flora, 174.
tle{K)sits of Java, 359.
fauna of Europe and North India,
383.
flora of Europe, 1 1 5.
or Eocene floras, 1 7(>.
Mississippi, matter carried away by. 1 04.
Mitten, Mr. William, on peculiar British
mosses and llepaticie, 335.
on temporary appearance of plants,
473.
Mniotiltido:, 47.
Muium, peculiar species of, in the Dnm-
tlieim mountains, 42G.
Moas of New Zealand, 439.
Mollusca, dispersal of, 73, 74.
Monotremata, restricted range of, 29.
Moraines, 1U3.
of Ivrea, 110.
Morgan, Mr. C. Lloyd, on thickness of
formations not affected by denuda-
tion, 210.
Moselv, Mr. H. N., on seeds carried by
' birds, 24G.
on the flora of Bermuda, 258.
Mosseti, {>cculiar British, 335.
non-European genera of in Britain,
336.
how diffiised and why restricted, 338.
Mount St. Elias, why not ice-clad, 146.
Mountain -chains aiding the dispersal of
plants, 77.
Mountain-cnains as aids to migmtiou uf
plants, 472.
Munia brunneicejtSy 425.
Mus, 1 7, 25.
Murray, Mr. J., on oceanic deposits, 82,
on chalk-like Globigerina ooze, 88.
MygaU Pyrenaica^ range of, 14.
MyialesUs heliaftthea, 425.
Afyrica Fayn, 247.
Myrsine, 177.
Nares, Capt. Sir G., on snow and ice in
high latitudes, 128.
on abrupt elevation of Bermuda, 251.
Nearctic Uegion, definition of, 46.
mammalia of, 46.
birds of, 47.
reptiles of, 48.
Nectarinea oseOf restricted range of, 1 5.
Neilgherries, Australian plants naturalized
in, 487.
Neotropical liegion, deflniiion of, 48, 49.
low types of, 50.
Nevill, Mr. Geoffrey, on land shells of the
Seychelles, 398.
on destruction of Seychelles flora, 408.
New species, origin of, 54.
Newton, Mr. E., on short wings of the
Seychelles dove, 401.
Newton, Professor, on recently extinct
birds, 401.
Newts, restricted range of, 29.
New Zealand, 434.
geology of, 435.
form of sea-bottom around, 435.
zoological character of, 436.
mammalia of, 436.
wingless birds of, 439.
European plants in, 439.
past changes of, 440.
winged birds and lower vertebrates
of, 445.
deductions from peculiarities of fauna
of, 446.
period of its union with North Aus-
tralia, 446.
the flora of, 449.
route of arctic plants to, 482.
endemic genera of plants in, 485.
great antiquity of, 485.
recent glaciation of, 154.
Nordenskjold, Professor, on absence of
perpetual snow in North Asia, 129.
on recent milder climate in Spitzber-
gen, 174.
on former polar climates, 1 79.
on geology of Spitzbergen, 1 80.
North America, glacial phenomena in, 1 10.
518
INDEX.
North America, interglacial warm periods
in, 115.
condition of, in Tertiary period, 185.
Northern genera of plants in south tem-
perate America, 480.
Hemisphere, absence of southern
plants from, 48().
flora, hardiness of, 487.
Oceaa currents as carriers of plants, 77.
as affecting interglacial periods, 14G.
as determining climate, 147.
effects of, in Tertiary times, 188.
Ocean, Darwin on permanence of, iKi.
Oceanic and continental islands, 230.
Oceanic ishinds, 231, 234.
— the Azores, 235.
general ramarks on, 305.
a proof of the permanence of oceans,
95.
Octodontidte, 26.
(Knanthe JluviatiliSy 333.
Oeningheii, miocene flora of, 1 75.
(Enothera odorata on a railway bank,
483.
Oliver, Professor, on pecaliar Bcrmudan
plants, 258.
Operculata, scarcity of, in the Sandwich
Islands, 299.
Ophryi api/eiHij temporary appearance of,
474.
Orchidece, species have restricted ranges,
4G5.
Orcliids, abundance of, iu Bourbon and
Mauritius, 401).
why almost universal in the tropics,
400.
Orders, distribution of, 20.
Organic change dependent on change of
conditions, 215.
Oriental region, definition of. 42.
mammals and birds of, 43.
reptiles of, 44.
insects of, 44.
Origin of new species, 54, 58.
of new genera, 59.
of the Galapngos flora, 273.
of the beetles of St. Helena, 281.
of Australian element in tlie New
Zealand flora, 45J).
Orkney, peculiar fishes of. 310, 318.
Orthonvx not a New Zealand genus,
445.
Osprey, wide range of, 15.
Ostriches, 28.
Otter-like mammal in New Zealand, 437.
Overlapping and discontinuous areas,
27, 28.
Pachyglossa aureoUmhata, 425.
Pakearctic region, limits of, 38.
characteristic features of, 39-41.
Palieozoic formations, depth of, round
London, 207.
Palm confined to Round Island, 407.
Panax, 177.
Papilio, 17.
Paraguay, no wild horses or cattle in,
216.
Pamassius, 40.
Parus ateTy 19.
P. boreaiU, 19, 63.
P. BritannictLs, 316.
P. Camt8cfiatk'ensi8f 19.
P. cinctus, 19.
P. c(EruIens^ 19.
/\ cristatuSy 19.
P. rijfaneus, 19.
P. fjedowif 1 9.
P. lugubrU^ 19.
P. major, ^8.
P. palustris^ 19.
discontinuous area of, 62.
P. roxta, 310.
P. Tenerifffw, 19.
Passeres of the Sandwich Islands, 296,
297.
Past changes of New Zealand, 440.
Paluia Reiniana, 256.
Payer, Lieutenant, on evaporation of ice
during the arctic summer, 133.
Peculiar fauna of New Zealand, deduc-
tions from, 440.
Pengelly, Mr., on submerged foi*ests, 310.
Pennuia millet, 206.
Permanence of continents, summary of
evidence for, 08, 00.
Permian formation, indiciitions of ice-nc-
tion in, 101.
Perodicticus, 25.
Petroselinum seqetum on railwav bank,
473.
Philippine Islands. 354, 355.
recent additions to fauna of, 355.
past history of, 355.
Phyllodaclyhts (ralapagensis, 205.
Phylloscn/ms horealis, range of, 15.
Piiysical causes which determine distribu-
tion, 401.
features of Formosa, 360.
Phrvniscido!, 27.
Pica', 17.
Pickering, Dr., on the flora of the Sand-
wich Islands, 302.
on families absent from the Sandwich
Islands, 301.
Pickering, Dr., on temperate forms on
INDEX.
519
inonntains of the Sandwich Isl-
ands, 302.
Pinus abies in Grinnell Land, 175.
Pithecia tnonachtts, 17.
P..rufibarbata^ 17.
Pitta, distribution of, 2.'».
Plants, dispersal of, 75.
seeds of, adapted for dispersal, 75, 76.
wide range of species and genera of,
176.
poverty of, in Ireland, 315.
peculiar British, 333.
of Ireland not in Great Britain, 334.
cause of their wide diffusion and
narrow restriction, 339.
how they migrate from north to
south, 472.
of existing genera throughout the
Tertiary period, 480.
southern migration of, by way of the
Himalayas, 482,483.
southern migration of, through Afri-
ca, 483,484.
endemic genera of, in New Zealand,
485.
Platypus, 29.
Plestiothn longiroxtris of Bermuda, 253.
Po, matter carried away by, 164.
Pndargus, 45.
Poinciana rfyia, 404.
Populus, 177.
Pourtales, Count, on modem formation of
chalk, 90.
on sedimentary deposits in Gulf of
Mexico, 211,212.
Poverty in S]>ecies of Britain, 813.
Precession of Kqtiinoxes, influence of, on
climate, 121.
Preservotion of sjiecies, 61.
Proboscidea, range of, 29.
Proteus, 61.
Psophia, range of species of, 1 8.
Ptcroptochidae, 28.
Pyrenean ibex, restricted range of, 14.
Railways, new plants on, 473,
linmsay, Professor, on ancient land sur-
faces, 94.
on geological time, 202.
on thickness of sedimentary rocks,
208.
Itit, native, of New Zealand, 437.
lijite of organic change usually measured
by an incorrect scale, 221.
Rats in the GahipagO!<, 264.
U iven, wide range of, 15.
Heade, T. Mclhird, on changes of sea and
land, 80.
Recent continental islands, 231.
Red clay of Bermuda, 252.
Reptiles, dispersal of, 71.
of tlie Galapagos, 264.
of the Sandwich Islands, 298.
cause of scarcity of, in British Isles,
314.
of Madagascar, 382.
of the Seychelles, 395.
of Mauritius and Round Island, 402.
of New Zealand, 445.
Rhodoloena aitivo/a, 403.
Rhus toxicodendron^ 258.
River channels, buried, 312.
Roches moutonn^eSj 102.
Rodents in Madagascar, 382.
Rosea Hibemica^ 333.
Round Island, a snake and a palm peculiar
to, 403, 408.
Rumex pulcher, in New Zealand, 475.
Rve, Mr. K. C, on peculiar British in-
sects, 320, 327, 329.
St. Helena, 276.
effects of European occupation on the
vegetation of, 278.
insects of, 281.
land shells of, 286.
absence of fresh-water organisms in,
288.
native vegetation of, 289.
Salvin, Mr., on the birds of the Galapa-
gos, 266.
Sandwich Islands, the, 293.
soologv of, 296.
birds of, 296.
reptiles of, 298.
land shells of, 298.
insects of, 300.
vegetation of, 300.
antiquity of fauna and flora of, 304.
Sassafras, 177.
Scandinavian flora, aggressive power of,
471.
Scientific voyages, comparative results of, 7.
Sciurus, 25.
Sclater, Mr. P. L., zoological regions of,
31,37.
Scotland, glacial deposits of, 107-1 10.
probable rate of denudation in, 165.
miocene flora of, 176.
peculiar fishes of, 316.
Scotophilus tuberculatunj 436.
Scrophularinese, why few species are com-
mon to Australia and New Zealand,
465.
Sea, depth of, around Madagascar, 380.
depth of, around Celebes, 414.
520
INDEX.
Sea -bol loin aroanJ New Zealand and
Australia, 430.
Snow maintains culd by reflecting the solar
lieat, 137.
Seti-leveK chanj::es of. dependent on glacia- i Snow and ice, )»roperties of, in relation to
tion, l.Kt. ' climate, 125.
complex ctfects of glaciiition on, 154, Snow-line, alterations of, causing migra-
l.V>. t ion of plants, 470.
rise of. a cause of denudation, ICG. • Sollas, Mr. J. W., on greater intensity of
Sens, inland, in Tertianr period, 182. telluric action in post time, 218.
Section of se;i-bottom near Bermuda, 251. Soatli Africa, recent glaciation of, 154.
Sedges and grasses common to Australia many northern genera of plants in,
and New ZenUnd, 403.
Sedimentary riK-ks, how to estimate thick- '
ness'of. 200.
tliinning-out of. 207.
how furmotl, 21KS.
thickness of, 200, 201>.
summarv of conclusions on tlie rate
of formation of the, 211, 497.
Seebohm. Mr., on Parus paiustris, 02.
on /imOfriza schitmcluSy 03.
on snow in Siberia, 1 58.
on birds of Ja|mn, 302.
Seeds dis|)ersal of, 244.
cjirried bv birds, 240.
ft '
^enerio Australisj on burnt ground, 473.
Sericinus, 40.
Seychelles Archipelago, 393.
birds of, 394.
reptiles and amphibia of, 395.
fresh-wnter fishes of, 397.
huul shells of, 398.
484.
its supposed connection with Aus.
tmlia, 484, 485.
South American plants in New Zealand,
485.
South temperate America, 51.
climate of, 140, 141.
Southern flora, comparative tenderness of,
487.
Southern plants, why absent in the North-
ern Hemisphere, 480.
Space, temperntare of, 123.
Specialization antagonistic to diflusion of
species, 405.
I SiKicies, extinction of, 00.
rise and decay of, 01.
epoch of exceptional stability of, 221.
I dying-out and replacement uf, 373.
preser\-ation of, in islands, ^74.
' Specific areas, 14.
S/tiranthes Romanzoviana^ 334.
Sharp, Dr. 1)., on peculiar British beetles, , Spitzbcrgen, Miocene flora of, 175.
320.
Shells peculiar to Britain, 3.'>2.
Shetland Isles, peculiar beetle of, 330.
Shore deposits, 81, 208.
proving the ])crmnnence of conti-
nents, 92, 93.
distance from coast of, 21 1.
Siberia, amount of snow and its sadden
disjippearance in, 133.
Silurian boulder-beds, 191.
warm arctic climate, 193.
Simiidae, 20.
Sisi/vinrhiuni riennudianum^ 258.
SkertchK'v, Mr., on four distinct boulder
thivs, 112.
Sluj; pccniiiir to Ireland, 332.
Snake ])eculiar ft) 1{ound Island, 403.
Snakes of the Galapagos, 205.
of the Se.vcheiies, 390.
Snow, effects of. on climate, 120.
absence of boulder-beds in, 179.
Stability of extreme glacial conditions,
150.
Stainton, Mr. H. T., on peculiar British
moths, 320-325.
Stanivoi mountains, why not ice-clad, 140.
, Stalling*, genera of in New Zcidand, 445-
I 448.
. Sleliaria mediae temporary appearance of,
474.
Sternum, process of abortion of keel of,
401.
Stow, ]SIr. (t. W., on glacial phenomena
■ in South Africa, 155.
, Stratified rocks formed near shores, 81,
' 83.
deposits, how formed, 208.
Striated rocks, 201,
blocks in the Permian formation,
1!U.
quantity of heat required to melt, I Strix /Ittmmfn, 15.
12
Struthiones, 30.
often of small amount in high lati- Struthious birds of New Zealand as indi-
tudes, 128. I eating past changes, 441.
never i)€rpetual on lowlands, 128. i Stylidium, 170.
conditions determining pcr])ctual) 132. ' Submerged forests, 310.
INDEX.
521
Subsidence of Istlinius of Panama, 1 43.
Sumatra, geology of, 353.
Sweden, two deposits of *' till '' in, 1 15.
Swimming powers of mammiilia, 01).
Swinlioe, Mr. Kobert, resenichcs in For-
mosn, 365.
Switzerlnnd, interglaciul warm periods in,
115.
Svlviadas, overlapping genera of, 28.
Talpida:, 40.
Tiipirs, distribution of, 24.
fuimer wide range of, 286.
Tarsius, 61.
Tarsius spectrum, 418.
Tasmania and North Australia, resem-
blance of, 5.
route of arctic plants to, 482.
Tazodium distichum in Spitzbergen, 175.
Temperate climates in arctic regions,
173.
Australian genera of plants in New
Zealand, 462.
Australian species of plants in New
Zealand, 462.
Temperature of space, 123.
how dependent on 8un*s distance, 1 23.
Tertiary glacial epochs, evidence against,
171.
warm' climates, continuous, 180.
Test of glaciation at any period, 167.
Testudo Abingdonii, 264.
T. microphyes^ 264.
Tetraogalluii, distribution of, 24.
Thais, 40.
Thomson, Sir William, on age of the
ciirth, 203.
Sir Wyvillc, on organisms in the
Globigerina ooze, 85.
Thrifothorvs Bewickii, discontinuitv of, 65.
•*Tiir* of Scotland, 107.
several distinct formations of. 111.
Tits, distribution of species of, 18, 19.
Torreya, 177.
Tortoises of the Galapagos, 264.
Trade-winds, how muditied by n glacial
epoch, 135.
Tragulidae, 26.
Travelled blocks, 104.
Tremarctos, an isolated genus, 28.
Triassic warm arctic climate, 193.
Tribonyx not a New Zealand genus, 445.
Trichoptera peculiar to Britain, 331.
Trogons, 27.
Tropical affinities of New Ztoland birds,
445.
character of the New Zealand flora,
caut»eof, 460, 461.
Tropica] genera common to New Zealand
and Australia, 461.
Turdus, 16,25.
Turdus/uscescetiSf variation of, 56.
Tylor, A., on evidence of floods during de-
IKJsit of gravels, 114.
on estimating the rate of denudation,
203.
Tyrannidffi, 47.
Urania, 27.
Uropeltidffi, 29.
Urotrichus, distribution of, 24.
Ursus, 25.
Variation in animals, 49.
amount of, iu North American birds,
55, 56.
Vegetation, local peculiarities of, 178.
eflects of polar night on, 189.
Vesperugo serotinus, range of, 1 4.
Vireonidae, 47.
Vireosijlvia gilcus and V. Swainsoniij 65.
Wallich, Dr., on habitat of G]obigerinie,88.
Wales, peculiar fish of, 31 7, 318.
Warm climates of Northern latitudes,
lung persistence of, 191.
Water, properties of, in relation to cli-
mate, 125, 126.
Watei house, Mr., on Galapagos beetles,
269.
Watson, Mr. 11. C, on the flora of the
Azores, 244.
on peculiar British plants, 333.
on vegetation of railway banks, 473.
Webb, Mr., on comparison of Mars and
the Karth, 157.
West Australia, rich flora of, 451, 455.
former extent and isolation of, 456.
West Indies. 50.
White, Dr. F. Buchanan, on the llemip-
tern of St. Helena, 187.
White, Mr. John, on native accounts of
the moa, 440.
Winged birds of New Zealand, 445.
Wingless birds never inhabit continents,
401.
their evidence against "Lemuria,"
402.
of New Zealand, 439.
Wings of Struthious birds show retro-
grade development, 443.
Winter temperature of Europe and Amer-
ica, 187.
Wolf, range of, 14.
Wollnston, Mr. T. V., on insular char-
acter of St. Helena, 278.
52-2 INDEX.
Wollaston, Mr. T. V., on St. Helena shells Young Islnnd, 481 .
and insects, 281. Young, Professor J., on contempornneous
Wood, Mr. Searles V., Jr., on formation formation of deposits, 210.
of "till," 109.
on alternations of climate, 112. Zoological and geographical regions com-
on causes of glacial epochs, 119. pared, 51.
conclusive objection to the eccentric- Zoological features of Japan, 359.
ity theory, 151, 152. | character of New Zcaaland, 436.
on continuous warm Tertiary cli- '■■ Zoology of Bermuda, 2.52, 253.
mates, 1 71. of the Sandwich Islands, 296.
Woodward, Mr., on " Lemnria," 391. of Borneo, 344, 345.
Wright, Dr. Percival, on lizards of the of islands round Celebes, 416.
Sevchell«», 395. of Celebes, 4 1 8.
THE END.
VOYAGE OF THE "CHALLENGER."
By Sir C. WYVILLE THOMSON, F.R.S.
THE VOYAGE OF THE "CHALLENGER." The
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