UlIlF S. B. Bill SJtbrarg
Jfortlj (Earcltna *tat^ Imiieraity
Q,H85
W18
1892
S00956719 .
This book is due on the date indie
below and is subject to an overdui
as posted at the Circulation Desk.
■:'3V - 0 1976
M /*i» / ^^ 1 .*r^'-'
^./iir V-,,
'%2 2Jfi0
ISLAND LIFE
CLr^^.Guc Q-^ O. C4
^:~hss^^
ISLAND LII-i:
OR
THE PHENOMENA AND rATRES OF
INSULAR FAUNAS AM) FLORAS
INCLUDING A REVISION AND ATTEMITKD SOLUTION OK
THE PROBLEM OF
GEOLOGICAL CLIMATES
ALFRED RUSSEL WALLACE
AUTHOR Of "the MALAY ARflllPEI-AGO," "THE r.EOORAPHKAL DISTRIBUTION OF
ANIMALS," " DARWINISM," ETC.
SECOND .IXD REVISED KDITinx
?i 0 n b 0 n
MAC MI LLA N AND < ' <>.
A N I) N i: W V n K K
isiir)
The liight oj Truiulation and lirproductioH ts lUuretd
Richard Clay and Sons, Limited,
london and bungay.
First Edition printed 1S80 (Med. Svo).
Second Edition 1S92 (Extra cr. Svo). Reprinted 1S95.
TO
SIR JOSEPH DALTON TTOOKKU,
K.C.S.I., C.B., F.R.S., ETC., ETC.
WHO, MOKK THAN ANY OTHER WRITER,
HAS ADVANCED OUR KNOWLEDGE OF THE GEOGRArHKAL
DISTRIBUTION OF PLANTS, AND ESrEGlALLV
OF INSULAR FLORAS,
^ gebicute this Dolumc;
ON A KINDRED SUBJECT,
AS A TOKEN OF ADMIILVTIUX AND KF.CAKI).
118574
CORRECTIONS IN PRESENT ISSUE.
The first issue of this Edition being exhausted, the opportunity is taken
of making a few corrections, the most important of which are here stated : —
Page 163. Statement modified as to supposed glaciation of South Africa.
Pages 174 and 338. Many geologists now hold that there was no great
submergence during the glacial epoch. The passages re-
ferring to it have therefore been re -written.
Page 182. Colonel Fiel den's explanation of the occurrence of large trees
on shores and in recent drift in high latitudes, is now
added.
,, 272. A species of Carex peculiar to Bermuda is now given.
,, 356. Geomalacus maculosus, as a peculiar British species, is now
omitted.
Verbal alterations have also been made at pages 41, 105, 356, and
360.
PREFACE TO THE SE(T)XI) EDITION
This edition has been caivfully revised throughout, and
owint^to the "-real increase to onr knowledge of the Natural
History of some of the islands during the last twelve years
considerable additions or alterations have been re([uircd.
The more im})()rtant of these changes are the following :—
Chapter VII. The account of the migrations of animals
and plants during and since the Glacial Epoch, has bucn
moditied to accord with newer information.
Chapters VIII and IX. The discussion of the causes of
Glacial Epochs and :\Iild Arctic Climates has beon some-
what modiiied in view of the late Dr. C-roU's remarks, and
the argument rendered clearer.
Chapter XIII. Several additions tu the Fauna .»f the
Galapagos have been noted.
Chapter XV. Considerable additions have been made
to this chapter embodying the recent discoveries of binls
and insects new to the Sandwich Islands, while a nnich
fuller account has been given of its highly peculiar and
very interesting flora.
Chapter XVI. Important additions and corrections hav.-
been made in the lists of i)eculiar British animals and
plants embodying the most recent inforniatioii.
Chapter XVII. Very large additions have been made
to the mammalia and birds of Borneo, and full list:* ot the
})e(!uliar sj)i'eies are given.
PREFACE TO FIRST EDITIOX
generall}^ that, so far as I am able to judge, a real
advance lias here been made in the mode of treating
problems in Geographical Distribution, owing to the firm
establishment of a number of preliminary doctrines or
" principles," which in many cases lead to a far simpler and
yet more complete solution of such problems than have
been hitherto possible. The most important of these
doctrines are those which establish 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
correspondents 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 chap-
ters dealing wdth questions on which they have special
knowledofe, gfivino- me the benefit of valuable emendations
and susforestions. Mr. Edward R. Alston has looked over
those parts of the earlier chaj^ters 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
geological questions ; Professor A. Newton 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 his remarks on my two chapters dealing with the
New Zealand flora.
Croydon, August, 1880.
CONTENTS
PART I
THE DISPERSAL OF ORGANISMS ; ITS PHENOMENA, LAWS, AND
CAUSES
CHAPTER I
INTKODUCTORY
Keinaikable Contrasts in tlie Distribution of Animals— Britain and Jai.an
—Australia and New Zealand— Bali and Lonibok— Florida and Bahama
Islands— Brazil and Africa— Borneo, Madagascar, and Celebes-
1 roblenis in Distribution to be found in every Country— Can be Solved
only by the Combination of many distinct lines of iiujuirv, Biolo^ncal
and Physical— Islands offer the best Subjects for the Study of Distribu-
tion—Outline ot the Subjects to be discussed in the Present Volume.
Pa<jts3 — \1
CHAPTER II
THE ELEMENTARY FACTS OF I)ISTKIIirTI..N.
Importance of Locality as an Essential Character of Si)ecies-Areas of
distribution— Extent and Limitations of Specific Aivas-SiK-cilic li^ince
0 ':^""'^'~^'''"^'"^:, Area-s-Separate and Oveilai-pin- Areas-The
bpecies of Iits as illustrating Areas of Distribution— Tiie Distribution
01 the Species of Jays— Discontinuous (Icncric Areas— IVculiarities o(
Generic and Family Distribution— CJeneral Features of Overlapping'
and Discontinuous A r.as- Restricted Areas of Families— The Distribu
tionot Orders I'mjrs 12--30
CONTETsTTS
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 — The
Range of British Birds— Range of East Asian Birds — The Limits of the
Paliearctic Region — Characteristic Features of the Palsearctic Region —
Definition and Characteristic Groups of the Ethiopian Region— Of the
Oriental Region — Of the Australian Region— Of the Nearctic Region
— Of the Neotropical Region — Comparison of Zoological Regions with
the Geographical Divisions of the Globe . , . Pages 31—54
CHAPTER lY
EVOLUTION AS 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 Species Arise from a Variable Species — Definition
and Origin of Genera — Cause of the Extinction of Species — The Rise
and Decay of Species and Genera — Discontinuous Specific Areas, why
Rare — Discontinuity of the Area of Parus Palustris — Discontinuity of
Emberiza Schoeniclus — The European and Japanese Jays — Supposed
examples of Discontinuity among North American Birds — Distribution
and Antiquity of Families — Discontinuity a Proof of Antiquity — Con-
cluding remarks " . • . Pages 55—71
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 Dispersal of Insects— The Dispersal of Land Mollusca
—Great Antiquity of Land-shells— Causes Favouring the Abundan-ce 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 Effecting their Distribution . Pages 72—82
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
CONTENTS
Formations ; the Origin of Chalk— Fn'sh- water and Shorodepositi m
Proving the IVrnianence of Continents — Oceanic Islands as ludicationR
of the I'ermancneo of Continents and Oceans— (Jencral Stahility
of Continents with Constant Change of Form— Elh-ct of Contin<iital
Changes on the I)i.stril)uti«»nof Animals — Changed I)istrihntion Proved
by the Extinct Animals of DillVrcnt Epochs— Summary of Evidence
for the General Pcrmaueuce of Continents and Oceans, i'afjcs 83—105
CHAPTER VII
CHANGES OF TLIMATE WHICH HAVE INFLUENCED THE niSPERSAL OF
ORGANISMS : THE GLACIAL EPOCH
Proofs of the Recent Occurrence of a Glacial Epoch— iMoraines-Travclled
Blocks— Glacial Deposits of Scotland : the "Till "—Inferences from
the Glacial Phenomena of Scotland— Glacial Phenomena of North
America- Edccts of the Glacial Epoch on Animal Life— Warm and
Cold Periods- Palreontologii-al Evidence of Alternate Cold and Warm
pt-riods — Evidence of Interglacial Warm Periods on the Continent and
in North America— Migrations and Extinctions of Organisms Caused
by the Glacial Epoch /V/^.s lOt)— 124
CHAPTER VIII
THE CAUSES OF GLACIAL EPOCHS
Various Suggested Causes— Astronomical Causes of Changes of Climate-
Difference of Temperature Caused by Varying Distances of th.> 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 Glaeial Epoch— Perpetual Snow nowhere Exists
on Lowlands— Conditions Determining the Presence or Absence of
Perpetual Snow— Eflicieiiev of Astronomical causes in Producing
Glaciation— Action of Meteorological Causes in Intensifying Glariation
— Summarv of Causes of Glaciation— Effect of Clouds and Fog in
Cutting off the Sun's Heat— South Temjx^rate Amerca a-s Illustrating
the Influence of Astronomical Causes on Climat. — (n-ographical Changrn
how fara Cause of (;laciation— Land Acting as a Parner to Ocean,
.unonts- The Theorv of Interglacial Periods an.l their 1 robablo
Character— Probable Effect of Winter in aphelion on the Climate ot
Britain— The Ess.ntial Principle of Climatal Change Restated—
Probable Date of the Last Glacial Epoch -Changes of the ^•'^•h'Vel
Dependent on (Uaciation -The Plan.'t Mars as Hearing on the |l»<*"0-
of Excentricitv as a Cause of (facial Epochs . /'"r- lii.— 168
CONTENTS
CHAPTER IX
ANCIENT GLACIAL EPOCHS, AND MILD CLIMATES IN THE ARCTIC
REGIONS
Mr. Croll's Views on Ancient Glacial Epochs— Effects of Denudation in
Destroying the Evidence of Remote Glacial 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 Regions — The Miocene
Arctic Flora— Mild Arctic Climates of the Cretaceous Period — Strati-
graphical Evidence of Long-continued Mild Arctic Conditions — The
Causes of Mild Arctic Climates — Geographical Conditions Favouring
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 Excentricity on Warm Polar
Climates — Evidences as to Climate in the Secondary and Palaeozoic
Epochs — Warm Arctic Climates in Early Secondary and Paleozoic 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 Phvsical Causes in Producing Changes of Climate.
Pages 169—209
CHAPTER X
THE earth's age, AND THE RATE OF DEVELOPMENT OF ANIMALS AND
PLANTS
Various Estimates of Geological Time— Denudation and Deposition of
Strata as a Measure of Time— How to Estimate the Thickness of the
Sedimentary Rocks — How to Estimate the Average Rate 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 Mutations as a Motive Power in Bringing
about Organic Changes — Climatal Revolutions as an Agent in Produc-
ing Organic Changes — Present Condition of the Earth One of Excep-
tional Stability as Regards Climate — Date of Last Glacial Epoch and
its Bearing on the Measurement of Geological Time — Concluding
Remarks Pages 210—240
rOXTFXTS
PART II
INSULAR FAUNAS AND FLORAS
CHArXER XI
THE CLASSIFICATION OF ISLANDS
Importance of Islands in the Stu<ly of the Distrihutiou of OiA'anisnis—
Classification of Islands with Rcferem-e to Distribution— Contim-ntal
Islands — Oceanic Islands Patjcs 241—24.')
CHAPTER XII
OCEANIC ISLANDS :— THE AZURES AND IJKKMUDA
The Azores, or JFestern Islands
Position and Physical Features— Chief Zoological Features of the Azores—
liirds— Origin of the Azorean Bird-fauna— Insects of the Azores— Laud-
shells of the Azores— The Flora of the Azores— The Disi)ersal of Seeds
— Birds as seed-carriers— Facilities for Dispersal of Azorean Plants
Important Deduction from the Peculiarities of the Azorean Fauna and
^'lora Pages 246—262
Bermuda
Position and Physical Features— The Red Clay of Bermuda— Zoology of
Bermuda— Birds of Bermuda — Comparison of the Bird -faunas of Ikr-
muda and the Azores— Insects of Bermuda— Land Mollusca— Flora of
Bermuda— Concluding Remarks on the Azores and Bermuda
I'cjcs 263 — 27 1
CHAPTER XIII
THE (JALATAGOS ISLANDS
Position and Physical Features— Absence of Indigenous Mammalia and
Amphibia— Reptiles— Birds— Insects and Land-shells— The Keeling
Islands as Illustrating the Manner in which Oceanic Islands are
Peopled— Flora of the Galaj>agos— Origin of the Flora of the Galapagos
— Concluding remarks ...... Pages 273 291
CHAPTER XIV
ST. HELENA
Position an. I Physical Features of St. Helena— Change ElToctod by Euro-
pean Occupation- Tile In.sects of St. Helena— Coleoptera—Pecu'liaritie.s
and Origin of the Coleoptera of St. Helena— Land-shells of St. Helena
—Absence of Fresh-water Organi.sms— Native Vegetation of St. Helena
—The Relations of the St. Helena Composit;e— Concluding Remarks
on St. Helena pages 292—300
CONTE^^TS
CHAPTER XV
THE SANDWICH ISLANDS
Position and Physical Features — Zoolog>' of the Sandwicli Islands — Birds
— Reptiles — 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 — General Remarks on Oceanic Islands
Pages 310^330
CHAPTER XVI
CONTINENTAL ISLANDS OF RECENT ORIGIN : GREAT BRITAIN
Characteristic Features of Recent Continental Islands — Recent Physical
Changes of the Britisli 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 Speciality 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 Britisli Flora — Peculiarities of the Irish
Flora — Peculiar British Mosses and Hepaticfe — Concluding Remarks on
the Peculiarities of the British Fauna and Flora . Pages 331 — 372
CHAPTER XVII
BORNEO AND JAVA
Position and Physical Features of Borneo — Zoological Features of Borneo :
Mammalia— Birds — The Affinities of the Borneo Fauna — Java, its
Position and Phj'sical Features— General Character of the Fauna of
Java— Ditferences Between 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 Changes of Java and Borneo —
The Philippine Islands— Concluding Remarks on the Malay Islands
Pages 373—390
CHAPTER XVIII
JAPAN AND FORMOSA
Japan, its Position and Physical Features— Zoological Features of Japan—
IMammalia— 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 Continental Islands . Pages 391—410
CONTENTS
CirAITEU XI\
ANCirNT rONTINF.NTAI, ISLANPS : rUF. MADAflASCAU fJItOIT
Remaiks on Ancient C'ontincMital Islund.s — riiysical Features of Madagjiscur
— Biological Features of Madagascar — Mainnialia — Reptiles — Relation
of Madagascar to Africa— Eaily History of Africa and ^Iadaga.srar —
Anomalies of Distribution and how to Explain Them — The ]{irds of
.Madagascar as Indicating a Supposed Lcinurian Continent — Submerged
Islands Between ]\Iadagascar and India — ('oncluding Remarks on
" Lemuria "' — The iMascarenc Islands — The Comoro Islands^Thc Sey-
chelles Archipelago — Birds of the Seychelles — Reptiles and Amphibia—
Fresh-water Fishes — Land Shells — Mauritius, Bourbon, and lii)driguez
— Birds — Extinct Birds and their Probable Origin — Re ptibs— Flora of
Madagascar and the Mascarene Islands— Curious Relations of Mascarene
I'lants — Endemic Genera of j\Iauritius and Seychelles— Fragmentary
Character of the Mascarene Flora — Flora of ]\Iadagascar Allied to that
<if South Africa — Preponderance of Ferns in the ^lascarene Flom —
Concluding Remarks en the Madagascar Group. . . Pages ill— A VJ
CHAPTER XX
ANOMALOUS ISLANDS : CELEBES
Anomalous Relations of Celebes — Physical Features of the Island — Zoo-
logical Character of the Islands Around Celebes— The Malayan and
Australian Banks — Zoology of Celebes: Mammalia — Probable Deriva-
tion of the Mammals of Celebes — Birds of Celebes — Bird-types Peculiar
to Celebes — Celebes not Strictly a Continental Island — Vecidiarities of
the Insects of Celebes — Himalayan Types of IJirds and liuttertlies in
Celebes — Peculiarities of Shape and Colour of Celebesian Buttertlies—
Concluding Remarks— Appendix on the Birds of Celebes
/%«450— 170
CHAPTER XXI
ANOMALOUS islands: NEW ZEALAND
osition and Physical Features of New Zealantl— Zoological Character of
New Zealand— Mammalia — "Wingless liirds Living and Extinct— Recent
Existence of the ]\Ioa— Past Changes of X.w Zealand deduced from
its Wingless Birds— Birds and Rejttiles of New Zealand Conclusions
from the Peculiarities of the New Zealantl Faumi . . Pages 471- 186
h
CONTENTS
CHAPTER XXII
THE FLORA OF NEW ZEALAND : ITS AFFINITIES AND PROBABLE ORIGIN
Relations of tlie New Zealand Flora to that of Australia — General Features
of the Australian Flora— The Floras of South-eastern and South-western
Australia — Geological Explanation of the Differences of these Two
Floras— The Origin of the Australian Element in the New Zealand Flora
— Tropical Character of the New Zealand 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 . . . Pages 487 — 508
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 — ]\Ieans by which Plants
have Migrated from Nortli to South — Newly Moved Soil as Affording
Temporary Stations to ]\Iigrating Plants — Elevation and Depression of
the Snow-line as Aiding the Migration of Plants — Changes of Climate
Favourable to Migration — The JMigration from North to South has
been Long going on — Geological Changes as Aiding ]\Iigration — Proofs
of Migration by way of the Andes — Proofs of ]\Iigration by way of the
Himalayas and Southern Asia — Proofs of ]\Iigration 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 . Pages 509 — 530
CHAPTER XXIY
SUMMARY AND CONCLUSION
The Present Volume is the Development and Application of a Theory-
Statement of the Biological and Physical Causes of Dispersal — Investi-
gation of the Facts of Dispersal — Of the Means of Dispersal — Of Geo-
graphical Changes Affecting Dispersal — 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 ]\Ir. CroU —
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 — 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
Pages 531 — 545
MAPS AND ILLUSTRATIONS
1. Mat siiowixu xin: DisxianrTioN of the tuue Jays
Frontispiece.
2. Map sikavixo the Zoor.ooicAL Regions . To fare 31
3. Mai' showinc the DisTninuTiox of Parl's Palustris
Tofacr Q(S
4. A (i LACIER WITH MoRAiXES (Fi'oiii Sir C, Lyoll's Priuciplcs
of Geology) • 109
5. Map of the Ancient Rhone Glacier (From Sir C LyrlTs
Antiquity of Man) . HO
6. Diagram showing the effects of Excentrktty and
Precession on Climate 1-7
7. Diagram of Excentrktty and Precession 129
8. Map showing the Extent <>f the North and South
Polar Ice 138
0. DiA(ntAM sHowiN(; Changes of Excentrdtty during Three
Million Years 171
10. Outline Map of the Azores . . 218
11. Map of I'ermuda and the Amep.ican Coast 263
VI. Skction of P.ermuda and adjacent Ska-rottom 261
XX IMAPS AND ILLUSTRATIONS
PAGE
13. Map of the Galapagos akd adjacent Coasts of South
Amepjca 276
14. Map of the Galapagos 277
15. Map of the South ATLAXTTf, showing position of St.
Helena 293
16. Map of the Sandavich Islands 311
17. Map of the North Pacific, with its submerged Banks . 312
18. Map showing the Bank connecting Britain with the
Continent 333
19. Map of Borneo and Java, showing the Great Submarine
Bank of South-Eastern Asia 373
20. Map of Japan and Formosa 392
21. Physical Sketch Map of Madagascar (From Nature) . . 413
22. ]\rAP of ]\L\dagascar Group, showing Depths of Sea . . 415
23. Map of the Indian Ocean 424
24. Map of Celebes and the surrounding Islands 451
25. Map showing Depths of Sea around Australia and New
Zealand 471
26. Map showing the probable condition of Australia
during the Cretaceous Epoch • 496
ISLAND LIFE
PAET I
THE DISPERSAL OF ORGANISMS
ITS PnEKOMF.XA, LA irs. AND CAUSES
CHAPTER I
INTRODUCTORY
Remarkable Contrasts in distribution 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 distribution to be found in every country — Can be soh'ed
only by tlie combination of many distinct lines of inquiry, biological
and physical — Islands offer the best subjects for the study of distribu-
tion— Outline of the subjects to be discussed in the 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.
The sunny isles of the Mediterranean, the sands and date-
palms of Egypt, the arid rocks of Aden, the cocoa groves
of Ceylon, the 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 review ; till after a circuitous
voyage of thirteen thousand miles he finds himself at
Hakodadi in Japan. He 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 he can hardly help fancying he is close
to his home. He finds the woods and fields tenanted by
tits, hedge-sparrows, wrens, wagtails, larks, redbreasts,
E ^ i> 2
D. H. HILL LIBRARY
North Carolina State College
ISLAND LIFE
thrushes, buntings, and house-sparrows, some absolutely
identical with our own feathered friends, others so closely
resembling them that it requires a practised ornithologist
to tell the difference. If he is fond of insects he notices
many butterflies and a host of beetles which, though on
close examination they are found to be distinct from ours,
are yet of the same general aspect, and seem just what
might 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 remove the general impression of a
wonderful resemblance between the productions of such
remote islands as Britain and Yesso.
Now let an inhabitant of Australia sail to New Zealand,
a distance of less than thirteen hundred miles, and he will
find himself in a country whose productions are totally
unlike those of his 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 vegetation 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 Lombok, 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 extremely n7ilike
those of the other, the difference being such as to strike
even the most ordinary observer. Bali has red and green
woodpeckers, barbets, weaver-birds, and black-and-white
magpie-robins, none of which are found in Lombok, where,
however, we find screaming cockatoos and friar-birds, and
the strange mound-building megapodes, which are all
equally unknown in BaU. 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
INTRODUCTORY
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.
In the western hemisphere w^e 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 Alabama or
Florida we still find ourselves in the midst of pines, oaks,
sumachs, magnolias, vines, and other characteristic forms
of the temperate flora; while the birds, insects, and land-
shells are of the same general character with those found
further north.^ But if we now cross over the narrow strait,
about fifty miles wide, which separates Florida from the
Bahama Islands, we find ourselves in a totally different
country, surrounded by a vegetation which is essentially
tropical and generally identical with that of Cuba. The
chano-e is most strikinof, because there is little difference
of climate, of soil, or apparently of position, to account for
it ; and when we find that the birds, the insects, and
especially the land- shells of the Bahamas are almost all
West Indian, while the North American types of plants
and animals have almost all completely disappeared, we
shall be convinced that such differences and resemblances
cannot be due to existing conditions, but must depend
upon laws and causes to which mere proximity of position
offers no clue.
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. Between 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 so much
nearer together. So the differences between the birds and
quadrupeds of temperate Tasmania and tropical North
' A small niimber of species bcloii^diig to the West Indies are Ibiiiul in
the extreme southern portion of the Florida Peninsula.
ISLAND LIFE rARt i
Australia are slight and unimportant as compared with
the enormous 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 tendency to produce
similarity in the animal world. The equatorial parts of
Brazil and of the West Coast of Africa are almost identical
in climate and in luxuriance of vegetation, but their
animal life is totally diverse. In the former we have
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 AustraUa, 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 vve visit the great islands of the globe, we find that
they present similar anomahes 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, although 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— v/e find that the two former, although
furthest 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, every country, and every island on the globe,
offers similar problems of greater or less complexity and
interest, and the time has now arrived when their solution
can be attempted with some prospect of success. Many
INTRODUCTORY
years study of this class of subjects has convinced me that
there is no short and easy method of dealing with them ;
because they are, 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 theQ^e 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 and land
which have affected those migrations — the whole series
of actions and reactions which have determined the
preservation of some forms and the extinction of others, —
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 know-
ledge of the fauna and fiora 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
'" I cannot avoid here referring to the enormous waste of labour 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 century. All these expeditions combined have done far
less than private collectors in making known the products of remote lands
and islands. They have brought home fragmentary collections, made in
widely scattered localities, and these have been usually described in huge
folios or quartos, whose value is often in inverse proportion to their bulk
and cost. The same species have been collected again anil again, often
described several times over under new names, and not unfrequently
stated to be from places they never inhabited. The result of this ^yretche(l
system is that the productions of some of the most frciiuently visited an<i
most interesting islands on the globe are still very imperfectly known,
while their native plants and animals are being yearly exterminated, and
I his is the case even with countries under the rule or protection of
ISLAND LIFE part i
never now be obtained owing to the reckless destruction of
forests and with them of countless species 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 affinities ; and it is only now that this is being
generally arrived at. We further have to make use of the
theory 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 explan-
ation of the complex facts of distribution toulcl 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. An-
other important factor in our interpretation of the phe-
nomena of distribution, is a knowledge of the extinct forms
that have inhabited each country during the tertiary and
secondary periods of geology. New 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 al-
ready obtained remarkable evidence of the migrations of
many animals and plants in past ages, throwing an often
unexpected light on the actual distribution^ 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
European governments. Such are the Sandwich Islands, Tahiti, the
Marquesas, the Philippine Islands, and a host of smaller ones ; while
Bourbon and ^^lauritius, 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 oin- possessions, and those of other
European 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 circumnavi-
gated the globe.
^ The general facts of Paleontology, as bearing on the migrations of
animal gi'oups, are summarised in my Geographical Distrihution of Animals,
YoL I. Chapters VI., YIL, and VIII.
CHAP. I INTRODUCTORY
have to trust to collateral evidence and more or less prob-
able hypothetical 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 enables 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
dimmishing in extent. Lastly, as a most valuable supple-
ment to geology, we require to know approximately, the
depth and contour of the ocean-bed, since this affords an im-
portant clue to the former existence of now-submerged lands,
uniting islands to continents, or affording intermediate
stations which have aided the migrations of many organ-
isms. This kind of information has only been partially
obtained 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 soundings have afforded a basis for an
explanation of one of the most difficult and interesting
questions in geographical biology — the origin of the fauna
aixcl 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 importance of which is only noAV beginning to be
recognised by students 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 luxuriant vegetation in the
other; and, secondly, the theory of the permanence of exist-
ing contiren's 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 tlian even the
geological changes of sea and land. It is therefore neces-
sary to consider the evidence for these climatal changes ;
10 ISLAND LIFE
and then, by a critical examination of their possible causes,
to ascertain whether they were isolated phenomena, Avere
due to recurrent cosmical actions, or were the result 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 glacial epochs and warm polar climates, we have the
key to explain and harmonize many of the most anom-
alous biological and geological phenomena, and one whicli
is especially valuable for the light it throws on the dis-
persal and existing distribution of organisms. The other
important theory, or rather corollary from the preceding
theory — that of the permanence of oceans and the general
stability of sontinents 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, however, appears to me to be conclusive ; and it is
certainly the most fundamental question in regard to the
subject w^e have to deal with : since, if we once admit that
continents and oceans may have changed places over and
over again (as many writers maintain), we lose all power
of reasoning on the migrations of ancestral forms of life,
and are at the mercy of every wild theorist who chooses to
imagine the former existence of a now-submerged contin-
ent 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 inter-
esting facts in the distribution and affinities of organic
forms are presented by islands in relation to each other
and to the surrounding continents. The study of the
productions of the Galapagos — so peculiar, 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 fartli and its inhabitants has hardly yet
CHAP. I
INTRODUCTORY 11
been recognised ; and it is in order to direct the attention
of naturalists to this most promising 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 contin-
ents undergoing some of the various changes to which they
are ever subject ; and the correlative proposition, that every
portion of our continents has again and again passed
through insular conditions, has not been sufficiently con-
sidered, but is, I believe, the statement of a great and
most suggestive truth, and one which lies at the founda-
tion 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 renders 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 studies, adapted to give us a command
of the more important facts and principles on which the
solution of such problems depends. The succeeding
eight chapters will therefore be devoted 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 geo-
logical time and the rate of organic development.
CHAPTER II
THE ELEMENTARY FACTS OF DISTRIBUTION
Importance of Locality as an essential character of Species— Areas of Dis-
tribution—Extent and Limitations of Specific Areas— Specific range of
Birds— 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 features 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 expressly to inhabit the countries in which they are
now found, their habitat was an ultimate fact which re-
quired no explanation. 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 inhabit another country was, that
the climate or general conditions of that country were not
suitable to it, but in what the unsuitability consistecl we
could rarely hope to discover. Hence the exact locality of
any species was not thought of much importance from a
scientific point of view, and the idea that anything could
be learnt 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 gener-
ally adopted, and it was seen that each animal could only
have come into existence in some area where ancestral
cHAi'. II THE ELEMENTARY FACTS OF DISTRIBUTION 13
forms closely allied to it already lived, a real and important
relation was established between an animal and its native
country, 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 evolution
theor3^ it is the resemblances rather than the diversities 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 pre-
sent state of the organic 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 Bistrihitioii. — Every species of animal has a
certain area of distribution to which, as a rule, it is per-
manently confined, although, no doubt, the limits of its
range fluctuate somewhat 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
apparent and some real exceptions to this rule. Some
animals are so adapted to certain kinds of country — as to
forests or marshes, mountains or deserts — that they cannot,
permanently, live elsewhere. These maybe found scattered
over a wide area in suitable spots only, but can hardly on
that account be said to have 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 Scotland and
Ireland. In central Europe it is unknown till we come to
the Alps, the Pyrenees, and the Caucasus, where it again
appears. This is one of the best cases known of the dis-
14 ISLAXD LIFE
continuous distribution of a f^pecies, there being a gap of
about a thousand miles between its southern limits in
Russia, 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 continent, 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
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
distinct varieties or sub-species, inhabit the intervening
districts.
Extent and Limitations of Specific Areas. — Leaving for
the present these cases of want of continuity in a species,
Ave find the most wide difference between the extent of
country occupied, varying in fact from a few square miles
to almost the entire 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, the elk, the arctic fox, the glutton,
the ermine, and some others. The common wolf of Europe
and Northern Asia is thought by many naturalists to be
identical with the variously coloured wolves of North
America extending from the Arctic Ocean to Mexico, in
which case this will have perhaps the widest range of any
species 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 be identical yet confined to the temperate
zones of the two hemispheres. Among the undisputed
species of mammalia the leopard has an enormous range,
extending all over Africa and South Asia to Borneo 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, Vesperugo serotinus, which is found over
the larger part of North America, Europe and Asia, as far
II THE ELEMENTARY FACT8 OF DISTRIBUTION 15
as Pekin, and even extends into tropical Africa, thus
rivalling the leopard and tlie wolf in tlie extent of cniintrv
it occupies.
Of very restricted ranges tliere are many examples, but
some of these are subject to doubts as to the distinctness
of the species or as to its geographical limits being really
known. In Europe we have a distinct species of ibex
(Ccqyra Pyrenaica) confined to the Pyrenean mountains,
while the true marmot is restricted to the Alpine range.
More remarkable is the Pyrenean water-mole {Mygak
Pyrenaica), a curious small insectivorous animal found only
in a few places in the northern valleys of the Pyi'enees.
In islands there are many cases of undoubted restriction
of species to a small area, but these involve a different
question from the range of species on continents where
there is no a^opareivt obstacle to their wider extension.
Sioccific range of Birds. — Among birds Ave find instances
of much wdder range of species, Avhich is only what might
be expected considering their powers of flight ; but, what
is very curious, w^c also find more striking (though
perhaps not more frequent) examples of extreme limita-
tion of range among birds than among mammals. Of the
former j^henomenon perhaps the most remarkable case is
that afforded by the osprey or fishing-hawk, which ranges
over the greater portion of all the continents, as far as
Brazil, South Africa, the Malay Islands, and Tasmania.
The barn owl (Strix flammea) 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 remote
countries, some of which seem undoubtedly to be distinct.
Among passerine birds the raven has 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 {Phylloscopus
horealis) ranges from arctic 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 {Cyanojika coolci)
confined to the central portions of the Spanish peninsula ;
and the Italian sparrow found only in Italy and Corsica.
16 ISLAND LIFE
In Asia, Palestine affords some examples of birds of very
restricted range — a beautiful sun-bird {Ncdarinm osca) a
peculiar starling (Amydrus tristramii) and some others,
being almost or quite confined to the warmer portions of
the valley of the Jordan. In the Himalayas 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 some other birds
being found only on the summits of these mountains.
The most wonderfully restricted ranges are, however, to be
found among the humming-birds of tropical America.
The great volcanic peaks of Chimborazo and Pichincha
have each a peculiar species of humming-bird confined to a
belt just below the limits of perpetual snow, while the
extinct volcano of Chiriqui in Yeragua has a species con-
fined to its wooded crater. One of the most strange and
beautiful of the humming-birds {Loddigcsia mimUlis) was
obtained once only, more than forty years ago, near
Chachapoyas in the Andes of northern Peru ; and though
Mr. Gould sent many drawings of the bird to people visiting
the district and for many years offered a high reward for a
specimen, no other has ever been seen ! ^
Tlie above details will sufficiently explain what is meant
by the " specific area " or range of a species. The very
wide and very narrow ranges are exceptional, the great
majority of species 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 conti-
nent in an east and west direction, but considerable
numbers are restricted either to the northern or the
southern half In Africa some species range over all the
continent south of the desert, while large numbers are
restricted to the equatorial forests, or to the ^ upland
plains. In North America, if we exclude the tropical and
the arctic portions, a considerable number of species range
over all the temperate parts of the continent, while still
^ Since these lines were ^^Titten, a fine series of specimens of this rare
humming-bird has been obtained from the same locality. (See Proc. Zool,
Soc. 1881, pp. 827-834.)
cHAi'. II THE ELEMKiNTAKV EACTS OE DISTRIBUTION
more are restricted to the east, the centre, or tlie 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,
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 glutton, 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, Camelus, 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
swallow-tailed butterflies, containing more than four hun-
dred species; and Cicindela, which includes our native
tiger beetles, has about the same number. Many genera
of shells are very extensive, and one of them — the genus
Helix, including the commonest snails, and ranging all over
the world — is probably the most extensive in the animal
kingdom, numbering about two thousand described
species. ^
Separate and Overlairping Areas. — The species of a genus
arc 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
^ Alany of these large genera are now subdivided, the divisions bein^,'
sometimes termed genera, sometimes snb-genera.
18 ISLAND LIFE
each other, each species occupying an area of its own
which rarely coincides exactly with that of any other
species of the same genus. In some cases, 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 beginning where the other ends ; but this is compara-
tively 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 {Pi'hcia ononachus ?)
comes up to the south bank of the Upper Amazon, while
immediately we cross over to the north bank w^e find
another species (Fithecia rufiharhnta ?). Among birds we
have the green jacamar (Galbida viridis), abundant on the
north bank of the Lower Amazon, while on the south
bank we have two allied species {Galhula rnfomridis and
G. cyancicollis) ; and among insects we have at Santarem
on the south bank of the Amazon, the beautiful blue
butterfly, Callithea scqophira, while almost opposite to it, at
Monte-alegre, an allied species, Callithea Lcpricuri 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 American
wading birds, called trumpeters, 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 Amazon there
are two species, one in its lower valley extending up to the
Rio 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 Madeira, one below it, and a third
near Para, probably separated from the last by the
Tocantins river.
Overlapping areas among the species of a genus is a more
common phenomenon, and is almost universal where these
species are numerous in the same continent. It is,
however, exceedingly irregular, so that we often find one
CHAP. II THE ELEMENTARY FACTS OF DISTRIBUTION 19
species extendiDg over a considerable portion of the area
occupied by the genus and including the entire areas of
some of the other species. So little lias 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 Dendrceca, 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 having
its particular range. Thus, I), clominica comes as far as
the middle Eastern States, D. cmntlea keeps west of the
Alleghanies, D. discolo?^ comes to Michigan and New
England ; four other species go farther north in Canada,
while several extend to the borders of the Arctic zone.
The Species of Tits as Illustrating Areas of Distribution.
— In our own hemisphere the overlapping of allied species
may be well illustrated by the various kinds of titmice,
constituting the genus Parus, several of which are among
our best known English birds. The great titmouse {Pants
major) has the widest range of all, extending from the
Arctic circle to Algeria, Palestine, and Persia, and from
Ireland right across Siberia to the Ochotsk sea, probably
following the 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 {Parus
atcr) which inhabits all Europe from the Mediterranean
to about 64° N. latitude, in Asia Minor to the Lebanon
and Caucasus, and across Siberia to Amooiiand and Japan.
The marsh tit {Parus palustris) 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. Closely allied to this — of which it is probably
only a variety or sub-species — is the northern marsh tit
(Parus horealis), which overlaps the last in Norway and
Sweden, and also in South Russia and the Alps, but
extends further north into Lapland and North Russia, and
thence probably in a south-easterly direction across
Central Asia to North China. Yet another closely- allied
species {Parus camtscJiatkensis) ranges from North-eastern
Russia iicross Northern Siberia to Lake Baikal and to
Hakodadi in Japan, thus overlapjnng Parus horLnlis in the
20 ISLAND LIFE
western portion of its area. Our little favourite, the blue
tit {Parus ccerulcus) 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
cyancus) overlaps the range of P. ccendeus in Western
Europe as far as St. Petersburg and Austria, rarely
straggling to Denmark, while it stretches all across Central
Asia between the latitudes 35° and 56° N. as far as the
Amoor valley. Besides these wide-ranging species there
are several others which are more restricted. Partis
teneriffcc, a beautiful dark blue form of our blue tit, inhabits
North-west Africa and the Canaries ; Pants ledouci, closely
allied to our coal tit, is found only in Algeria ; Parus
lugubris, allied to the marsh tit, is confined to South-east
Europe and Asia Minor, from Hungary and South Russia
to Palestine ; and Parus cinchis, 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 cristatus) is some-
times placed in a separate genus. It inhabits nearly all
Central and South Europe, wherever there are pine forests,
from 64° N. latitude to Austria and North 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 tliere are many
others inhabiting 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 highlands of Mexico.
The Distribution of the Species 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 ascertaining their actual distribution, it has
not been found practicable to illustrate this genus by
means of a map. For this purpose 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
n THE ELEMENTARY FACTS OF DISTKIIiUTIOX 21
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 passing 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 Pala^arctic ^ genera. The
following are the species, beginning with the most westerly
and proceeding towards the east. The numbers prefixed
to each species correspond to those on the coloured maj)
which forms the frontispiece to this volume.
1. Garrulus glandarivs. — The common jay, inhabits the
British 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
Russia, up to, but not beyond, the Urals. The jays being-
woodland birds are not found in open plains or barren
uplands, and their distribution is hence by no means
uniform within the area they actually occupy.
2. Garrulus ccrricalis. — The Algerian jay, is a ver}^
distinct species inhabiting a limited area in North Africa,
and found in some places along with the common species.
3. Garrulus hryrdcld. — The black-headed jay, is closely
allied to the common species, but quite distinct, inhabiting
a comparatively small area in South-eastern Europe, and
Western Asia.
4. Garrulus atricajnllus. — The Syrian jay, is very closely
allied to the last, and inhabits an adjoining area in Syria,
Palestine, and Southern Persia.
5. Garridus hyrcanus. — The Persian jay, is a small
species allied to our jay and only known from the Elburz
Mountains in the north of Persia.
6. Garridus hrandti. — Brandt's jay, is a very distinct
species, having an extensive range across Asia from the
Ural Mountains to North China, ^landchuria, and the
northern island of Japan, and also crossing the Urals into
^ The Pal.nearctic region iucludos temperate Asia and Europe, as \\ ill be
explained in the next chapter.
22 ISLAND LIFE paut i
Russia where it has been found as far west as Kazan in
districts where the common jay also occurs.
7. Garrulm lanceolatus. — The black-throated jay, is a
very distinct form known only from the Nortli-western
Himalayas and Nepal, common about Simla, and extend-
ing into Cashmere beyond the range of the next species.
8. Gamtlvs hupecidaris. — The Himalayan jay is also
very distinct, having the head coloured like the back, and
not striped as in all the western species. It inhabits the
Himalayas east of Cashmere, but is more abundant in the
western than the eastern division, though according to the
Abbe David it reaches Moupin in East Thibet.
9. Garrnlus sinensis.— The Chinese jay, is very closely
allied to the Himalayan, of which it is sometimes classed
as a sub-species. It seems to be found in all the southern
mountains of China, from Foochow on the east to Sze-chuen
and East Tliibet on the west, as it is recorded from Mou-
pin- by the Abbe David as Avell as the Himalayan bird— a
tolerable proof that it is a distinct form.
10. Garrnlus taivanus.— The Formosan jay is a very
close ally of the preceding, confined to the island of
Formosa.
11. Garruhis japonicus. — The Jaj)anese jay is nearly
allied to our common British species, being somewhat
smaller and less brightly coloured, and with black orbits ;
yet these are the most widely separated species of the
genus. According to Mr. Seebohm this species is equally
allied to the Chinese and Siberian jays.
In the accomj)anying 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 Mr.
Seebohm's recent work 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 modi-
fications 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
CHAP. II THE ELEMENTARY FACTS OF DISTRTHrTTOX 23
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 isolation of many of the species ; while the next most
striking feature 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 Eiu'opean G.
f/landarius and the Asiatic G. Brandt i. The former has
three species overlapping it — in Algeria, in South-eastern
and North-eastern 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 0) form a group which
are isolated from the rest of the genus ; while the
Japanese jay (No. 11), is also completely isolated as
regards the European jays to which it is nearly 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
essentially non-migratory in their habits, though
sometimes moving southwards 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 disconnected 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
24 ISLAND LIFE
that of the bkie magpies, forming the gemis Cyaiiopica.
()ne species (C. cooki) is confined (as already stated) to the
wooded and nioimtaino\is districts of Spain and Portugal,
while the only other species of the genus (C. cyamts) is
found far away in North-eastern Asia and Japan, so that
the two species are separated by about 5,000 miles of
continuous land. Another case is that of the curious little
water-moles forming the genus Mygale, one species 3f.
muscovitica, being found only on tlie banks of the Yolga
and Don in South-eastern Russia, while the other, M.
fyrenaica, 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 Chasmorhynchus,
each of which appears to inhabit a restricted area com-
pletely separated from the others. The most northerly
is C. tricamnculatus of Costa Rica 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 nu-
merous caruncles on the throat, perhaps conterminous with
the last ; in Guiana, extending to near the mouth of the
Rio Negro, we have C. niveus, 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.
nudicollis, inhabits South-east Brazil, and is also white,
but with black stripes over the eyes, and with a naked
throat. These 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 colours.
They are therefore know^n to the native 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
hom£, 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 6,000
to 11,000 feet above the sea, and accompanying the ibex in
its wanderings, as both feed on the same plants. Another
, iiAi'. II THE KLEMKXTARV FACTS OK DISTRIP.UTIOX 25
has a wider range in Asia Minor aiul Persia, from the
Taurus mountains to the South-east corner of the Caspian
Sea ; a third species inhabits the Western Himalayas,
between the forests and perpetual snow, extending east-
wards to Nepal ; while a fourth is found on the north side
of the mountains in Thibet, and the ranges of these two
perhaps overlap ; the last species inhabit the Altai moun-
tains, and like the two first appears to be completely
separated from all its allies.
There are some few still more extraordinary cases in
Avhich 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 s}3ecies 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 abund-
ant in tropical Africa, but there are two outlying species,
one in the Eastern Himalaya mountains, the other in
Borneo, both very rare, and recently an allied species has
been found in the Malay peninsula. The beautiful blue
and green thrush-tits forming the genus (Jochoa, have two
species in the Eastern Himalayas and Eastern China,
while the third is confined to Java ; the curious genus
Eupetes, supposed to be aUied to the dippers, has one
species in Sumatra and Malacca, while four other species
are found two thousand miles distant in New Guinea;
lastly, the lovely ground-thrushes of the genus Pitta,
range from Hindostan to Australia, while a single
species, far removed from all its near allies, inhabits West
Africa.
Peculiarities of Generic and Family Distrihution. — The
examples 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.
D. H. HILL LIBRARY
26 ISLAND LIFE
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 except the mice from
Australia, while the genus Mus, which occurs 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
separate 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 Australia and tropical Africa ; Cervus
(the deer genus) with nearly the same range ; and Sciurus
(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 8,000 and 12,000 feet elevation; several
genera of finches each confined to limited portions of the
higher Himalayas, the blood-pheasants (Ithaginis) found
only above 10,000 feet from Nepal to East Thibet; the
bald-headed starling of the Philippine islands, the lyre-
birds of East Australia, and a host of others.
It is among the different genera of the same famil}^ that
we meet with the most striking examples of discontinuity,
although these genera are often as unmistakably allied as
are the species of a genus ; and it is these cases that furnish
the most interesting problems to the student of distribution.
CHAP. It THE ELEMENTARY FACTS OF DISTRIBUTION
We must therefore consider tliein somewliat more
fully.
Among mammalia the most remarkable of these divided
fjxmilies is that of the camels, of which one genus
Oamelus, the true camels, comprising the camel and
dromedary, is confined to Asia, while the other Auchenia,
comprisng the llamas and alpacas, is found only in the
liigh Andes and in the plains of temperate South America.
Not only are these two genera separated by the Atlantic
and by the greater part of the land of two continents, but one
is confined to the Northern and the other to the Southern
hemisphere. The next case, though not so well known, is
equally remarkable ; it is that of the Centetidse, a family
of small insectivorous animals, which are wholly confined
to Madagascar and the large West Indian islands Cuba
and Hayti, the former containing five genera and the latter
a single genus with a species in each island. Here again
we have the whole continent of Africa as w^ell as the
Atlantic ocean separating allied genera. Two families (or
subfamilies) of rat-like animals, Octodontidfe and
Echimyida?, are also divided by the Atlantic. Both are
mainly South American, but the former has tw^o genera in
North and East Africa, and the latter also two in South
and West Africa. Two other families of mammalia,
though confined to the Eastern hemisphere, are yet
markedly discontinuous. The Tragulidae are small deer-
like animals, known as chevrotains or mouse-deer,
abimdant in India and the larger Malay islands and
forming the genus Tragulus ; while another genus,
Hyomoschus, is confined to West Africa. The other
family is the Simiid?e or anthropoid apes, in which we have
the gorilla and chimpanzee confined to West and Central
Africa, while the allied orangs are found only in the islands
of Sumatra and Borneo, the two groups being separated
by a greater space than the Echimyida^ and other rodents
of Africa and South America.
Among birds and reptiles we have several families,
which, from being found only wdthin the tropics of Asia,
Africa, and America, have been termed tropicopolitan
groups. The Megalsemidie or barbets are gaily coloured
28 ISLAXD LTFP:
fruit-eating l3irds, 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 natural one. The
trogons form a family of very gorgeously coloured and
remarkable insect-eating birds very abundant in tropical
America, less so in Asia, and with a single genus of two
species in Africa.
Among reptiles Ave have two families of snakes — the
Dendrophidfe or tree-snakes, and the Dryiophidse or green
whip-snakes — which are also fonnd 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 America. The lizards forming the family
Amphisbaenidae are divided between tropical Africa and
America, a few species only occurring in the southern
portion of the adjacent temperate regions ; while even the
peculiarly American family of the iguanas is represented
by two genera in Madagascar, and one in the Fiji and
Friendly Islands. Passing on to the Amphibians the
worm-like Cseciliadse are tropicopolitan, as are also the
toads of the family Engystomatidae. Insects also furnish
some analogous cases, three genera of Cicindelida?,
(Pogonostoma, Ctenostoma, and Peridexia) showing a
decided connection between this family in South America
and Madagascar ; while the beautiful family of diurnal
moths, Uraniida^, is confined to the same two countries.
A somewhat similar but better known illustratioai 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 Overlapinng and Discontinuovs
Areas. — These numerous examples of discontinuous genera
and families form an important section of the facts of
animal dispersal v/hich any true theory must satisfactorily
account for. In greater or less prominence they are to be
found all over the world, and in every group of animals,
and they gTade imperceptibly into those cases of conter-
minous and overlapping areas which we have seen to
>HAP. II THE ELEMENTARY FACTS OF DISTRIBUTION 29
prevail in most extensive groups of species, and which are
perhaps even more common in those large families which
consist of many closely allied genera. A sufficient proof
of the overlapping of generic areas is the occurrence of a
number of genera of the same family together. Thus in
France or Italy about twenty genera of warblers (Sylviadse)
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 America a large
proportion of the genera of monkeys of the family Cebidse
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 extensive families no genus whose area does not
overlap that of many others. Then among the moderately
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 further
south ; the Bovidse, or hollow-horned ruminants, which
have a few isolated genera in the Rocky Mountains and
the islands of Sumatra and Celebes ; and from these we
pass on to the cases of wide separation already given,
Bestrided Arcccs of Families. — As families sometimes
consist of single genera and even single species, they often
present examples of very restricted range ; but what is
perhaps more interesting are those cases in Avhich a family
contains numerous species and sometimes even several
genera, and yet is confined to a narrow area. Such are
the golden moles (Chrysochloridas) consisting of two
genera and three species, confined to extratropical South
Africa ; the hill-tits (LiotrichidaB), a family of numerous
genera and species mainly confined to the Himalayas, but
with 'd few straggling species in the Malay countries and
the mountains of China; the Pteroptochidse, large wren-
like birds, consisting of eight genera and nineteen species,
almost entirely confined to temperate South America and
30 ISLAND LIFE
the Andes ; and the birds-of-paradise, consisting of nine-
teen 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 (Uropeltid?e), the five genera and
eighteen species being strictly confined to Ceylon and the
southern parts of the Indian Peninsula.
The Distrihution of Orders. — When we pass to the larger
groups, termed orders, comprising several families, we find
comparatively few cases of restriction and many of world-
wide distribution ; and the families of which they are
composed are strictly comparable to the genera of which
families are composed, inasmuch as they present examples
of overlapping, or conterminous, or isolated areas, though
the latter are comparatively 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 ^veil-defined portions of the globe. Thus
the Proboscidea, comprising the single family and genus of
the elephants, and the Hyracoidea, that of the Hyrax or
Syrian coney^ are confined to parts of Africa and Asia ;
the Marsupials to Australia and America ; and the
Monotremata, the lowest of all mammals — comprising the
duck-billed Platypus and the spiny Echidna, to Australia
and New Guinea. 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
salamanders — are similarly restricted to the northern
hemisphere.
These various facts will receive their explanation in a
future chapter.
CHAPTER III
CLASSIFICATION OF THE FACTS OF DISTRIBUTION. —
ZOOLOGICAL REGIONS
The Geogi-aphical 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
Palffiarctic Region— Characteristic featnres of the Palffiarctic Region —
Definition and characteristic groups of the Ethioynan Region— Of the
Oriental Region— Of the Australian Region— Of the Ncarctic 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
dispersed 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.
We 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
32 ISLAND LIFE
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 large portion of Euro^^e.
There are, indeed, a few species limited to Central or
Western or Southern Europe, and these are almost the
only cases in which Ave can use tlie word tor zoological
purposes without having to add to it some portion of
another continent. Still less useful is the term Asia for
this purpose, since there 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 an unique example,
while the cases in which Asiatic animals and groups are
strictly limited to a portion of Asi-a., or extend also into
Europe or into Africa or to the Malay Islands, are exceed-
ingly 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 character-
istic of South America are found also beyond the isthmus
of Panama, in what is geographically part of tlie 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 modifications, come into pretty
general use in this country, and tu some extent also
ZOOLOGICAL REGIONS
33
abroad ; we shall tlicrcfore proceed to explain its nature
and the principles on wliich it is estahlishcd, 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 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.
The Banqc of British Mcunmals as indicatinf/ a Zoological
Bcgion. — We will first take our commonest wild mammalia
and see how far they extend, and especially whether they
are confined to Europe or range over parts of other
continents :
Wild Cat
Fox
Weasel ...
Otter
Badger ...
Stag
Hedgehog
Mole
Squirrel . . .
Dormouse
Water-rat
Hare
Rabbit ...
Europe
Europe
Europe
Europe
Europe
Europe
Europe
Europe
Europe
Europe
Europe
Europe
Europe
N.
Africa
Siberia, Afghanistan.
N.
Africa
Central Asia to Amoor.
N.
Africa
Central Asia to Amoor.
N.
Africa
Siberia.
N.
Africa
Central Asia to Amoor.
N.
Africa
Central Asia to Amoor.
Central Asia to Amoor.
—
Central Asia.
Central A.sia to Amoor.
_.
Central Asia to Amoor
W. Siberia, Persia.
X.
Africa
—
We thus see that out of thirteen of our commonest
quadrupeds 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 entire
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 example, the quadrupeds of Germany, we
shall find that these too, although much more numerous,
are confined to the same limits, except that some of the
34 ISLAND LIFE tart i
more arctic kinds, as already stated, extend into the colder
regions of North America.
Range of East Asian and North African Mammals.—
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 terrestrial species (omitting the
bats, the seals, and other marine animals), and of these no
less than twenty-six are identical with European species,
and twelve or thirteen more are closely allied representa-
tives, leaving only five or six which are peculiarly Asiatic.
We can hardly have a more convincing proof of the
essential oneness of the mammalia of Europe and Northern
Asia.
In Northern Africa we do not find so many European
species (though even here they are very numerous) be-
cause a considerable number of West Asiatic and desert
forms occur. Having, however, shown that Europe and
Western Asia have almost identical animals, Ave may treat
all these as really European, and we shall then be able to
compare the quadrupeds of North Africa with those of
Europe and West Asia. Taking those of Algeria as the best
known, we find that there are thirty-three species identical
with those of Europe and West Asia, while twenty-four
more, though 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
CHAP. Ill ZOOLOGICAL REGIONS 35
region of which Europe forms a part, we will now examine
the birds, in order to see how hv tliey agree in their
distribution with the mammalia. Of late years great
attention has been paid to tlie 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 edited by
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. In order to confine our exami-
nation within reasonable limits, and at the same 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 Bihd.s which extend to North Africa and Central
OR North-east Asia.
1. Lanius collurio Red backed Shrike (also all Africa).
2. OHolus Galbula Golden Oriole (also all Africa).
3. Turdus musicus Song-Thriisli.
4. ,, iliacus Red-wing.
5. ,, pilaris Fieldfare.
6. Monticola saxatilis Blue rock Thrush.
7. Ruticilla succica Bluethroat (also India in winter).
8. Saxi€ola ruhicola Stonechat (also India in winter).
9. ,, cenanthc Wheatear (also N. America).
10. Acrocephahts arundinaceus. Great Reed-AVarblcr.
II. Sylvia ciirruca Lesser Whitethroat.
12. Parus major Great Titmouse.
13. Motacilla sulp'hurca Grey Wagtail (also China and Malaya).
14. ., raii Yellow Wagtail.
1 5. Anthns trivialis Tree Pipit.
16. ,, spiloletta Water Pipit.
17. , , campestris Tawny Pipit .
18. Alauda arvensis Skylark.
19. , , cristata Crested Lark.
1) '1
ISLAND LIFE
20. Emheriza sehceniclus Reed Bunting.
21. ,, citrinella Vellow-hammor.
22. Fringilla montifringilla ... Branibling.
23. Passer montanus Tree Sparrow (also S. Asia).
24. „ clomesticus House Sparrow.
25. Coecothraustes vulgaris Hawfinch.
26. Carduelis spinus Siskin (also China).
2 7 . Loxia curvirostra Crossbill .
28. Stnrnus vulgaris Starling.
29. Pyrrhocorax gramlus Chough.
30. Corvus corone Crow. i a • n
31 . Eirundo rustica Swallow (all Africa and Asia). _
32. Cotyle riparia Sand Martin (also India and N. America).
II. British Birds which range to Central or North-east Asia.
1 . Lanius excubitor Great Grey Shrike.
2. Turdiis varius AVhite's Thrush (also to Japan ).
3. ,, atrigularis Black-throated Thrush.
4. Acrocephalus iicevius Grasshopper Warbler.
5. Plnjlloscopus superciliosus . . . Yellow-browed Warbler.
6. CertMafamiliaris Tree-creeper.
7. Pants cccruleus Blue Titmouse.
8. ,, ater Coal Titmouse.
9. „ ^;a^Ms<r^■s I\[arsh Titmouse.
10. Acrcdula caudata Long-tailed Titmouse.
1 1 . Ampelis garrulus Wax-wing. _
12. Anthus richardi Richard's Pipit.
13. Alauda alpestris Shore Lark (also N. America).
14. Pledrophanes nivalis Snow-Bunting (also N. America).
15. ,, lapp)onicus ... Lapland Bunting.
1 6. Emheriza rustica Rustic Bunting (also China).
17. , , jmsilla Little Bunting.
18. Linota linaria Mealy Redpole (also N. America).
19. Pyrrhula erythrina Scarlet Grosbeak (also N. India, China).
20. , , enudeator Pine Grosbeak (also N. America).
21 . Loxia Ufasdata Two-barred Crossbill .
22. Pastor roseus Rose-coloured Starling (also India).
23. Corvus corax Raven (also N. America).
24. Pica rustica Magpie.
25. Nucifraga caryocatactcs Nutcracker.
III. British Birds ranging into N. Africa and W. Asia.
1 . Lanius minor Lesser Grey Shrike.
2. ,, aiLriculatus Woodchat (also Tropical Africa).
3. Muscicapa grisoJa Spotted Flycatcher (also E. and S.
Africa).
4. ,, atricapiUa Pied Flycatcher (also Central Africa).
5. Turdus viscivorus Mistletoe -Thrush (N. India in winter).
6. ,, mcrula ,. Blackbird.
7. , , torquatus Ring Ouzel.
8. Accentor modularis Hedge Sparrow.
9. Erithacus ruhecula Redbreast.
10. Daidiasluscinia Nightingale.
ZOOLOGICAL REGIONS
11. Riiticilla phcenicurus Redstart,
12. , , tithys Black Redstart.
13. Scuvicola ruhctrif Whinchat.
14. Aedon galadodcs Rufous "Warbler.
1 5. Acrocephalus strcpcrus Reed Warbler.
16. ,, schccnohcnus . . . Sedge Warbler.
17. Melizophilus undatus Dartford Warbler.
1 8. Sylvia rufa Greater Whitethroat.
19. . , salicaria Garden Warbler.
20. ,, airicapilla Blackcap.
21 . , , orphca Orphean Warbler.
22. riiylloscopus sihilatrix Wood Wren.
23. . , trochilus Willow Wren.
24. ,, collyhUa Chiffchaff.
25. Rcfjidus o'istat^Ls Golden-crested Wren.
26. , , ignicapillus Fire-crested Wren.
27. Troglodytes parvulus Wren.
28. Silta ccesia Nuthatch,
29. Motacilla alba White Wagtail (also W, Africa).
30. , , flava Pjlue-hoaded AVagtail.
31 . Anthus pratcnsis ]\Ieadow- Pipit.
32. A lauda arhorca Woodlark.
33. Calaiulrclla hrachydadyJa. . Short-toed Lark.
34. Emlcriza miliaria Common Bunting.
35. , , drills Cirl Bunting.
36. „ liortulana Ortolan.
37. Fringilla coelchs Chaffinch.
38. Coccothraustcs chlori Greenfinch.
39. Serinus hortulanus Serin.
40. Carduclis clegans Goldfinch.
41. Linota cannahina. Linnet.
42. Corvus monedula Jackdaw.
43. Chclidon urhica ITouse-Martin.
IV. BlUTISH BlUDS RANGING TO XoKTH AFRICA.
1 . Hypolais idcrina Icterine "Warbler.
2. Acrocephalus aquaticns Aquatic Warbler.
3. , , luscinioiden Savi's Warbler.
4. Motacilla lugubris Pied Wagtail.
5. Pyrrhula curopcca Bullfinch.
6. Garrulus glandarius Jay.
Y. British Birds ranging to West Asia only.
1 . Accentor collaris Alpine Accentor.
2. Muscicapa 2Mrva Red-brcasted Flycatcher (to N. W I ndiaV
3. Panurus hiarmicus Bearded Titmouse.
4. Mclanocorypha sibirica . . . White-winged Lark.
5. Euspiza laclanoccphala . . . Black-headed Bunting.
6. Linota Jlavirostriii Twite.
7. Corvusfriigilegus Rook.
VI. BiiiTisii Birds confined to Eui;orj:.
1. Cinclus aquaticu."^ Dipper (closel}' allied races inhabit other
parts of the Pala-arctic Region).
2. Fanes crisiatus Crested Titmouse.
ISLAND LIFE PART I
3. Anthus obscurus Rock Pipit.
4. Linota rufesccns Lesser Redpoll (closely allied races in
N. Asia and N. America).
5. Loxia pityopsiUacus Parrot Crossbill (a closely allied form in
N. Asia).
We find, that out of a total of 118 British Passeres
there are :
82 species which range to North Africa and Central
or East Asia.
25 species which range to Central or East Asia, but
not to North Africa.
43 species which range to North Africa and Western
Asia.
6 species which range to North Africa, but not at
all into Asia.
7 species which range to West Asia, but not to North
Africa.
5 species which do not range out of Europe.
These figures agree essentially with those furnished by
the mammalia, and complete the demonstration that all
the temperate 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 continent. 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 Russian naturalists
and afford us the means of making the required comparison.
There are 151 species belonging tu the orders Passeres and
Picarise (the perching and climbing birds), and of these no
less than 77, or more than half, are absolutely identical
ZOOLOGICAL REGIONS 39
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 species are migrants from South-eastern
Asia. The resemblance is therefore equally close which-
ever 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 " northem
old-world " region — a name now well known to naturalists.
The Limits of the Palceardic Region. — The boundaries
of 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 w^est it extends to the ocean, and
includes a number of islands wdiose 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 Africa
we meet with our first difficulty. The Euro-Asiatic
animals 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 sandy
ocean 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 convenience, to consider
the geographical line of the tropic of Cancer to form the
boundary. We are thus enabled to define the Palaearctic
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 Persian Gulf. Persia and Afghanistan undoubtedly
belong to the Palaearctic region, and Baluchistan should
probably go with these. The boundary in the north-
\vestern part of India is again difficult to determine, but it
40 ISL.O'D LIFE
cannot be far one way or the other from the river Indus as
far up as Attock, opposite the mouth of the Cabool river.
Here it will bend to the south-east, passing a little south
of Cashmeer, and along the southern slopes of the
Himalayas into East Thibet and China, at heights varying
from 9,000 to 11,000 feet according to soil, aspect, and
shelter. It may, jDcrhaps, be defined as extending to the
upper belt of forests 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 warblers of northern
genera, with wrens, numerous titmice, and a great variety
of buntings, grosbeaks, bullfinches and rosefinches, 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 demarkation 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 country it cannot be marked in
detail on any map.
Further east in China it is still more difficult to
determine the limits of the region, owing to the great
intermixture of migrating birds ; tropical forms passing
northwards in summer as far as the Amoor river, Avhile 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 Palaearctic region a little south of
Shanghai on the east coast. Several tropical genera come
as far north 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 boundary 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
ZOOLOGICAL REGIONS 41
China and East Thibet in about 32° N. 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 Paloearctic, although its extreme southern portion,
owing to its mild insular climate and evergreen vegetation,
gives shelter to a number of tropical forms.
Characteristic Features of the I'alccarctic Region. — Having
thus demonstrated the unity of the Paloearctic region by
tracing out the distribution of a large pro23ortion of its
mammalia and birds, it only remains to show how far it is
characterised by peculiar 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 distin-
guished by possessing two peculiar genera of Talpida? or
moles, the family being confined to the Pal^earctic and
Nearctic regions. The true hedgehogs (Erinaceus) are also
characteristic, being only found elsewhere in South Africa
and in the northern part of the Oriental region. Among
Carnivora, the racoon-dog (Nyctereutes) of North-eastern
Asia, and the true badgers of the genus Meles are peculiar,
most other parts of the world possessing distinct genera of
badgers. It has six peculiar genera, or subgenera, of
deer ; seven peculiar genera of Bovidse, chiefly antelopes ;
wliile the entire group of goats and sheep, comprising
twenty-two species, is almost confined to it, one sijccies only
occurring in the Rocky mountains of North America and an-
other in the Nilgiris of Southern India. Among the rodents
there are nine genera with twenty- seven species wholly
confined to it, while several others, as the hamsters, the
dormice, and the pikas, have only a few species elsewhere.
In birds there are a large number of peculiar genera of
which we need mention only 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 warblers, including the robins ; the bearded tit-
mouse and several allied genera; the long-tailed titmice
forming the genus Acredula ; the magpies, choughs, and
nut-crackers ; a host of finches, among whicli the bull-
finches (Pyrrhula) and the buntings (Embcriza) are the
42 ISLAND LIFE
most important. The true pheasants (Phasianus) are
wholly Pal^arctic, 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 Palsearctic region in its warmer portions has a
considerable number, and among these are many which
are peculiar to it. Such are four genera of snakes, seven of
lizards, five of frogs and toads, and twelve of newts and
salamanders ; while of fresh-w^ater fishes there are about
twenty peculiar genera.^ Among insects we may mention
the elegant Apollo butterflies of the Alps as forming a
peculiar genus (Parnassius), only found elsewdiere in the
Rocky 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 w^e
can only now refer to the great family of Carabidae, or
predaceous ground-beetles, which are immensely numerous
in this region, there being about fifty jDeculiar genera ; while
the larf^e and handsome ofenus Carabus, wn'th its allies Pro-
cerus and Procrustes, containing nearly 300 species, is almost
wholly confined to this region, and would alone serve to dis-
tinguish it zoologically from all other parts of the globe.
^ The following list of the genera of rcj»tiles and amphibia peculiar to
the Palsarctic Region has been furnishetl nie by Mr. G. A. Boulenger, of
the British Museum : —
Snakes, Frogs and Toads.
Achaliniis— China, Japan. Fdobates—Enr., S.W. Asia.
Ccelopeltis—S. Eur., N. Af., S.W. PeZoc-f//te?—W. Europe.
j^si^_ Bm-or/Iossus — S. Eur., N.W. Af.
Macroprotodov^k'. Eur., X. Af. Bomhiiuitor—Ewx., Temp. Asia.
Taphrcnnctopon—QQni. Asia. Alyius—Qei-ii. and A\ . Eur.
Kewts.
Li/^AiiDs. Salaimmdra—^MX., /N. Af., S.AV.
Phrynocephalus— Cent. an<l S.W. Asia.
Asia. Chioglossa — Spain and Portugal.
Anguis — Europe, W, Asia. Salarnandn' net— Italy.
Blanlts—S.^V. Eur., X.AV. Ai'rica, Fachi/triton~-Y,ast Thibet.
S.W. Asia. Hynohius — China and Japan.
TrogonopMs—l^.y^. Africa. Gcomolgc—E. JManchuria.
Zacerta— Em: Temp. Asia, X. 0)iychodactylus—Ja,])an.
Africa (one sp. in SalamandreUaSiheria.
W. Af.). Ranidcns — Siberia.
Psammodro7nm—S.V^ . Eur., N.W. Bairachyperus— East Thibet.
Africa. MyalolMtrachus — China. Japan.
Algiroidca — S. Eur. Proteus — Caverns of S. Austria,
CHAP. Ill ZOOLOGICAL REGIONS 43
Having given so full an exposition of the facts which
determine the extent and boundaries of the Palcearctic
region, there 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
Region. — The Ethiopian region consists of all tropical and
south Africa, to which are appended the large island of
Madagascar and the Mascarene Islands to the east and
north of it, though these differ materially from the con-
tinent, and will have to be discussed in a separate 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 Palaearctic region.
Taking first the mammalia, w^e find the following re-
markable animals at once separating it from the Palsearctic
and every other region. The gorilla and chimpanzee, the
baboons, numerous lemurs, the spotted hyaena, the aard-
wolf and hysena-dog, zebras, the hippopotamus, giraffe.
and more than seventy peculiar antelopes. Here we have
a wonderful collection of large and peculiar ([uadrupeds,
but the Ethiopian region is also characterised by the
absence of others wdiich are not only abundant in the
Palsearctic region but in many tropical regions as well.
The most remarkable of these deficiencies are the bears
the deer and the 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 isolated groups; such are the
potamogale, a curious otter-like water-shrew, discovered
by Du Chaillu in West Africa, so distinct as to constitute
a new family, PotamogalidtB ; the goldenmoles, also
forming a peculiar family, Chrysochlorida? ; as do the
elephant-shrews, Macroscelididte ; the singular aard-varks,
or earth-pigs, forming a peculiar family of Edentata callctl
Oryctcropodidoe ; while there are numerous peculiar genera
of monkeys, swine, civets, and rodents.
Among birds the most conspicuous and remarkable arc,
the great-billed vulture-crows (Corvultur), the long-tailed
44
ISLAND LIFE tAKT l
whydah finches (Vidua), the curious ox-peckers (Buphaga),
the splendid metallic starlings (Lamprocolius), the hand-
some plantain-eaters (Musophaga), the ground-hornbills
(Bucorvus), the numerous guinea-fowls belonging to four
distinct genera, the serpent-eating secretary-bird (Serpent-
arius), the huge boat-billed heron (Balseniceps), and the
true ostriches. There are also three quite ^ pecuhar
African farailies, the Musophagidse or plantain-eaters,
including the elegant crested touracos ; the curious
little finch-like colies (Coliidse), and the Irrisoridse,
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 sufficiently familiar to require notice in a
work of this character, 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
Getoniidse; and some of the Achatina^, which are the
largest of all known land-shells.
Dcfiniiion and Char ad eristic Groups of the Oriental
Jiefjion.^The Oriental region comprises all Asia south of
the Pala^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 portion 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-Australian, both of which have
been proposed, but are objectionable, as being already in
use in a different sense.
The great features of the mammals of the Oriental region
are, the long-armed apes, the orcing-utans, the tiger, the
sun-bears and honey-bears, the tapir, the chevrotains or
mouse-deer, and the Indian elephant. Its most conspicuous
birds are the immense number and variety of babbling-
thrushes (Timaliid?e), its beautiful little hill-tits (Liotrich-
ida3), its green bulbuls (Phyllornithidae), its many varieties
CHAP. Ill ZOOLOGICAL REGIONS 45
of the crow-family, its beautiful gapers and pittas adorned
with the most delicate colours, its great variety of hornbills,
and its magnificent Phasianida?, comprising the peacocks,
argus-pheasants, fire-backed pheasants, and jungle-fowl.
Many of these are, it is true, absent from the jDeninsula
of Hindostan, but sufficient remain there to ally it with
the other parts of the region.
Among the remarkable but less conspicuous forms of
mammalia 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 Tarsius (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 squirrels ; 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 Ortho-
tomus are found over the whole region and almost alone
serve to characterise it, as do the fine laughing-thrushes,
forming the genus Garrulax ; while the beautiful grass-
green fruit-thrushes (Phyllornis), and the brilliant little
minivets (Pericrocotus), 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 distributed,
and which may be said to characterise the region, is Gallus,
comprising the true jungle-fowl, one of which, Gallus ban-
kiva, is found from the Himalayas and Central India to
Malacca, Java, and even eastward to Timor, and is the
undoubted origin of almost all our domestic poultry. South-
ern India and Ceylon each possesses distinct species of
jungle-fowl, and a third very handsome gTceu bird (Gallus
aeneus inhabits Java.)
Reptiles are as abundant as in Africa, but they present
no well-known groups which can be considered as specially
characteristic. Among insects we may notice the magni-
46 ISLAND LIFE
ficent golden and green Papilionidae of various genera as
being unequalled in the world ; while the great Atlas moth
is probably the most gigantic of Lepidoptera, being some-
times ten inches across the wings, which are also very
broad. Among the beetles the strange flat-bodied Malayan
mormolyce is the largest of all the Carabida^, while the
catoxantha is equally a giant among the Buprestida^. 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 beauty.
Definition and Glmractcrisiic Growps of the Australian
Region. — The Australian region is so well marked off from
the Oriental, as well as from all other parts of the world,
by zoological peculiarities, that we need not take up much
time in describing it, especially as some of its component
islands will come under review at a subsequent stage of our
work. Its most important portions are Australia and New
Guinea, but it also includes all the Malayan and Pacific
Islands to the east of Borneo, Java, and Bali, the Oriental
region terminating with the submarine bank on which
those islands are situated. The island of Celebes is in-
cluded in this region from a balance of considerations, but
it almost equally well belongs to the Oriental, and must
be left out of the account in our general sketch of the
zoological features of the Australian region.
The great feature of the Australian region is the almost
total absence of all the forms of terrestrial mammalia which
abound in the rest of the world, their place being supplied
by a great variety of Marsupials. In Australia and New
Guinea there are no Insectivora, Carnivora, nor Ungulata,
while even the rodents are only represented by a few small
rats and mice. In the remoter Pacific Islands mammals
are altogether absent (except perhaps in New Zealand),
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 peculiarities in the mammalia
^ Remains of the dingo have been found fossil in Pleistocene deposits but
the auti(iuity of man in Au.^tralia is not known. It is not, however, im-
i'HAF. Ill zooT.O(arAL heoioxs 47
are so great that every naturalist agrees that Australia
must be made a separate region, the only difference of
opinion being as to its extent, some thinking that New
Zealand should form another separate reoion ; but tliis
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, flycatchers, shrikes, crows, and other familiar
types of the Eastern Hemisphere; yet a considerable
number of the most characteristic Oriental families are
absent. Thus there are no vultures, woodpeckers, pheas-
ants, 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 (Meli-
phagida?), 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 black
cockatoos, and the gorgeously coloured brush-tongued
lories ; the almost equal abundance of fine pigeons more
gaily coloured than any others on the globe ; the strange
brush-turkeys and mound-builders, the only birds that
probable that it may be as great as in Europe. My friend A. C. Swiiiton,
Esq., while working in the then almost unknown gold-held of Maryborough,
Victoria, in January, 1855, found a fragment of a well-formed stone axe
resting on the metamorphic schistose bed-rock about five feet beneath the
surface. It was overlain by the compact gravel drift called by the miners
" cement," and by an included layer of hard iron-stained sandstone. The
fragment is about an inch and three-eighths wide and the same length, and
is of very hard hne-grained black basalt. One side is ground to a very
smooth and regular surface, terminating in a well-formed cutting edge more
than an inch long, the return face of the cutting part being about a quarter
of an inch wide. The other side is a broken surface. The weapon appears
to have been an axe or tomahawk closely resembling that figured at p. 335
of Lumholtz's Among Cannibals, from Central Queensland. The fragment
was discovered by Mr. Swinton and the late Mr. :Mack worth Shore, one of
the discoverers of the gold-field, l^cfore any rush to it had taken place, and
it seems impossible to avoid the conclusioii that it was formed ]nior to thi'
deposit of the gravel drift and iron-stained sandstone under wliich it lav.
This would indicate a great antiquity of man in Australia, and would enable
us to account for the fossilised remains of the dingo in Pleistocene deposits
as those of an animal introduced by man.
48 ISLAND LIFE part i
never sit upon their eggs, but alloAv them to be hatched,
reptile-like, by the heat of the sand or of fermenting vege-
table matter; and lastly, the emus and cassowaries, in
which the wings are far more rudimentary 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
sufficient to show the distinctness and isolation of the
Australian region, we will now pass to the consideration
of the Western Hemisphere
Definition and Characteristic Gron'ps of the Nearctic
Region. — The Nearctic region comprises all temperate and
arctic North America, including Greenland, the only doubt
being as to its southern boundary, many northern types
penetrating into the tropical zone by means of the high-
lands and volcanic peaks of Mexico and Guatemala, while
a few which are characteristic of the tropics extend
northward into Texas and California. There is, however,
considerable evidence showing that on the east coast the
Rio Grande del Norte, and on the west a point nearly
opposite Cape St. Lucas, form the most natural boundary ;
but instead of being drawn straight across, the line bends
to the south-east as soon as it rises on the flanks of the
table-land, forming a deep loop which extends some distance
beyond the city of Mexico, and perhaps ought to be con-
tinued along the higher ridges of Guatemala.
The Nearctic region is so similar to the Palaearctic in
position and climate, and the two so closely approach each
other at Behring Straits, that we cannot wonder at there
being a certain amount of similarity between them — a
similarity which some naturalists have so far over-estimated
as to think that the two regions ought to be united. Let
us therefore carefully examine the special zoological fea-
tures of this region, and see how far it resembles, and how
far differs from, the Palsearctic.
At first sight the mammalia of North America do not
seem to difier much from those of Europe or Northern
Asia. There are cats, lynxes, wolves and foxes, weasels,
bears, elk and deer, voles, beavers, squirrels, marmots, and
ZOOLOGICAL REGIONS 49
hares, all very similar to those of the Eastern Hemisphere,
and several hardly distinguishable. Even the bison or
" buffalo " of the prairies, once so abundant and character-
istic, is a close ally of the now almost extinct '' aurochs " of
Lithuania. Here, then, we undoubtedly find a very close
resemblance between the two regions, and if this were all,
we should have great difficulty in separating them. But
along with these, we find another set of mammals, not
quite so conspicuous but nevertheless very important. We
have first, three peculiar genera of moles, one of which, the
star-nosed mole, is a most extraordinary creature, quite un-
like anything else. Then there are three genera of the
weasel family, including the well-known skunk (Me2:>hitis),
all quite different from Eastern forms. Then we come to
a peculiar family of carnivora, the racoons, very distinct
from anything in Europe or Asia ; and in the Rocky
Mountains we find the prong-horn anteloi^e (Antilocapra)
and the mountain goat of the trappers (Aj)locerus), both
peculiar genera. Coming to the rodents we find tliat the
mice of America differ in some dental peculiarities from
those of the rest of the world, and thus form several
distinct genera ; the jumping mouse (Xapus) is a peculiar
form of the jerboa family, and then we come to the
pouched rats (Geomyidte), a very curious family consisting
of four genera and nineteen species, peculiar to North
America, though not confined 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 mammalia which distinguish
the northern region of the new world from that of tlie old.
We must add to these loeculiarities some remarkable
deficiencies. The Nearctic region has no hedgehogs, nor
wild pigs, nor dormice, and only one wild sheep in the
Rocky Slountains 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 thrushes and wrens,
tits and finches, and what seem to hv warblers and
flycatchers and starlings in abundance ; but a closer exam-
ination shows the ornithologist that what he took for the
£
50 ISLAND LIFE
latter are really quite distinct, and that there is not a single
true flycatcher of the family Muscicapidae, or a single
starling of the family Sturnidse in the whole ^ continent,
while there are very few true warblers (Sylviidae), their
place being taken by the quite distinct families Mniotiltidse
or wood-warblers, and Vireonidoe or greenlets. In like
manner the flycatchers of America belong to the totally
distinct family of tyrant-birds, Tyrannidoe, and those that
look like starlings to the hang-nests, Icteridss ; and these
four peculiar families comprise about a hundred and
twenty species, and give a special character to the
ornithology of the country. Add to these such peculiar
birds as the mocking thrushes (Mimus), the blue jays
(Cyanocitta), the tanagers, the peculiar genera of cuckoos
(Coccygus and Crotophaga), the humming-birds, the wild
turkeys (Meleagris), and the turkey-buzzards (Cathartes),
and we see that if there is any doubt as to the mammals
of North America being sufficiently distinct to justify the
creation of a separate region, the evidence of the birds
would alone settle the question.
The reptiles, and some others of the loAver animials, add
still more to this weight of evidence. The true rattle-
snakes are highly characteristic, and among the lizards are
several genera of the peculiar American family, the
Iguanidai. Nowhere in the world are the tailed bat-
rachians so largely developed as in this region, the Sirens
and the Amphiumidse forming two peculiar families, while
there are nine peculiar genera of salamanders, and two
others allied respectively to the Proteus of Europe and the
Sieboldia or giant salamander of Japan. There are seven
peculiar families and about thirty peculiar genera of
fresh-water fishes ; while the fresh-water molluscs 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
animals, we find the Nearctic region to be exceedingly well
characterised, and to be amply distinct from the Palsearctic.
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 occupy the debatable ground
between the Palsearctic, Ethiopian, and Oriental regions.
CHAr. Ill ZOOLOGICAL REGIONS 51
If, however, we compare the iiuniber of species, which are
common to the Nearctic and Pala^arctic regions with tlie
number common to the western and eastern extremities of
the latter region, we shall find a wonderful difference
between the two cases ; and if we further call to mind the
number of important groups characteristic of the one
region but absent from the other, we sliall 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 North-eastern Asia in the bonds of
zoological unity.
Definition and Character istic Groups of the Neoiroineal
Region. — The Neotropical region requires very little defi-
nition, 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 Australia, which, however, it far ex-
ceeds 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 pecu-
liar to it. Such are, among mammalia — the prehensile-
tailed monkeys and the marmosets, the blood-sucking bats,
the coati-mundis, the peccaries, the llamas and alpacas, the
chinchillas, the agoutis, the sloths, tlie 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 conti-
nent can boast of. Among birds we have the charming
sugar-birds, forming the family Coerebidse ; the immense
and wonderfully varied group of tanagers ; the exquisite
little manakins, and the gorgeously-coloured chatterers ;
the host of tree-creepers of the f;imily Dendrocolaptida3 ;
the wonderful toucans; the puff-birds, jacamars, todies and
motmots ; the marvellous assemblage of four hundred dis-
tinct 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 gi'oups
of birds ; and no less wonderful is its richness in species,
since these fully equal, if they do not surpass, those of the
E 2
52 ISLAND LIFE
two great tropical regions of the Eastern Hemisphere (the
Ethiopian and the Oriental) combined.
As an additional indication of the distinctness and
isolation of the Neotropical region from all others, and
especially from the whole Eastern Hemisphere, we must
say something of the otherwise widely distributed groups
Avhich 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 Viverridai or civet family is wholly
wanting, as are every form of sheep, oxen, or antelopes ;
while the swine, the elephants, and the rhinoceroses of the old
Avorld are represented by the diminutive peccaries and tapirs.
Among birds we have to notice the absence of tits, true
flycatchers, shrikes, sunbirds, starlings, larks (except a soli-
tary species in the Andes), rollers, bee-eaters, and pheasants,
while warblers 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,
marsupials, and rodents form the majority of the terrestrial
mammalia ; while such higher groups as the carnivora and
hoofed animals are exceedingly deficient. Among birds a low
type of Passeres, characterised by the absence of the singing
muscles, is excessively prevalent, the enormous groups of
the ant-thrushes, tyrants, tree-creepers, manakins, and
chatterers belonging to it. The Picarise (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 former to the
brush-turkeys of Australia, the latter (very remotely) to
the ostriches, two of the least developed types of birds.
Whether, therefore, we consider its richness in peculiar
forms of animal life, its enormous variety of species, its
numerous deficiencies as compared with other 23arts of the
world, or the prevalence of a low type of organisation
among its higlier animals, the Neotropical region stands
out as undoubtedly the most remarkable of the great
zoological divisions of the earth.
In reptiles, amphibia, fresh-water fishes, and insects,
ciiAv. Ill ZOOLOGICAL REOIONS 53
this region is equally peculiar, but we need not refer to
these here, our only object now being to establish by a
sufficient number of well-known and easily remembered
examples, the distinctness of each region from all others,
and its unity as a whole. 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 por-
tion of South America including Chili and Patagonia.
In Central America, and especially in Mexico, we have
an intermixture of South American and North American
animals, but the former undoubted^ 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 abTuid-
ant. 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, chatterers, with many hum-
ming-birds and parrots, representing eighteen peculiar
Neotropical genera; a fact which decides the region 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 considerable proportion of north temperate forms. But
it contains armadillos, cavies and opossums ; and its birds
all belong to 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, cliatterers, toucans, trogons,
or motmots; but there are abundance of hang-nests,
tyrant-birds, ant-thrushes, tree-creepers, and a fair pro-
54 ISLAND LIFE part i
portion of humming-birds, tanagers and parrots. The zoology
is therefore thoroughly Neotropical, although somewhat
poor ; and it has a number of peculiar forms of strictly Neo-
tropical types — as the chinchillas, alpacas, &c., which are
not found in the tropical regions except in the high Andes.
Comimrison of Zoological Regions vnih the Gcogra/jpliical
Divisions of the Glohe. — 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 geogi-aphical
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 we remember this, and keep their
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 type of the
Ethiopian and Australian regions. Europe and Asia
require more important modifications. The European
fauna does indeed well represent the Palsearctic 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 with the zoological pri-
mary divisions of the earth is sufficiently clear. In order
to make these relations visible to the eye and more easily
remembered, we will put them into a tabular form :
Regions. Geogra]iliical Equivalent.
Palsearctic Europe, with nortli temperate Africa and Asia.
Ethiopian Africa (south of the Sahara) with Madagascar.
Oriental Tropical Asia, to Philippines and Java.
Australian . . . Australia, with Pacific Islands, Moluccas, kc.
Nearctic North America, to North Llexico.
Neotropical ... South America, with tropical N. America and W. Indies.
The following arrangement of the regions will indicate
their geographical j^osition, and to a considerable extent
their relation to each other.
N E A R C T I C P A L ^ A R C T I C
I I
I Oriental
Ethiopian I
Ned- I
Tropical Australian
CHAPTER IV
EVOLUTION THE KEY TO DISTRIBUTION
Importance of the Doctrine of Evolution — The Origin of Xew Species-
Variation in Animals — Tlie Amount of Variation in North American
Birds — How New Species arise from a Variable Species — Definition and
Origin of Genera — Cause of the Extinction of Species — The Rise and
Decay of Species and Genera — Discontinuous Specific Areas, why Rare —
Discontinuity of the Area of Parus Palustris — Discontinuity of Emberiza
Schoeniclus — The European and Japanese Jays — Supposed Examples of
Discontinuity among Nortli American Birds — Distribution and Antiquity
of Families — Discontinuity a proof of Antiquity — Concluding Remarks.
In the preceding chapters we have explained the general
nature 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 absolutely
necessary to have a clear comprehension of the collateral
facts and general principles to which we shall most
frequently have occasion to refer. These may be briefly
defined as, the powers of dispersal of animals and plants
under different conditions, such as geological and cHmatal
changes, and the origin and development of species and
groups by natural selection. This last is of the most
fundamental importance, and its bearing on the dispersal
56 ISLAND LIFE
of animals has been much neglected. We therefore devote
the present chapter to its consideration.
As we have already shown in our first chapter that the
distribution of species, of genera, and of families, present
almost exactly the same general phenomena in varying
degrees of complexity, and that almost all the interesting-
problems we have to deal with depend upon the mode of
dispersal of one or other of these ; and as, further, our
knowledge of most of these groups, in the higher animals
at least, is confined to the tertiary period of geology, it is
therefore unnecessary for us to enter into any questions
involving the origin of more comprehensive groups, such
as classes or orders. This enables us to avoid most of the
disputed questions as to the development of animals, and
to confine ourselves to those general principles regulating
the origin and development of species and genera which
were first laid down by Mr. Darwin thirty years ago, and
have now come to be adopted by naturalists as established
propositions in the theory of evolution.
The Origin of New Species. — How, then, do new species
arise, supposing the world to have been, physically, much
as we now see it ; and what becomes of them after they
have arisen ? In the first place we must remember that
new species can only be formed when and where there is
room for them. If a continent is fully stocked with
animals, each species being so well adapted for 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 no change takes place, no new
species will arise. For every place or station is supposed
to be filled by creatures in all respects adapted to sur-
rounding conditions, able to defend themselves from all
enemies, and to obtain food notwithstanding the rivalry of
many competitors. But such a perfect 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 when we
find the individuals of one species ranging into different
IV EVOLUTION THE KEY TO DISTRIBUTION
climates, subsisting on different food, and competing with
different sets of animals, Avliile the individuals of another
species will be limited to a small area beyond which they
seem imable to extend. When a change occurs, either of
climate or geography, some of the small and ill-adapted
species will probably die out altogether, and thus leave
room for others to increase, or for new forms to occupy
their places.
But the change will most likely affect even flourishing
s^Decies in different ways, some beneficially, others inju-
riously. Or, again, it may affect a great many injuri-
ously, to such an extent as to require some change in their
structure or habits to enable them to get on as well as be-
fore. Now "variation" and the "struggle for exist-
ence " come into play. All the weaker and less perfectly
organised 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 be almost sure to be formed.
Variation in Animals. — To make this more intelligible
to those who have not considered the subject, and to
obviate the difficulty many feel about "favourable
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 generation, if
we could examine all the individuals of any common
species, we should find considerable differences, not only
in size and colour, 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 different domestic breeds have
been produced. Think of the difference in every limb, and
every bone and muscle, and probably in every part,
internal and external of the whole body, between a grey-
hound and a bull-dog ! Yet, if we had the complete series
of ancestors of these two breeds before us, we should ))rob-
58 ISLAND LIFE
ably find that in no one generation was there a greater
difference than now occurs in the same breed, or sometimes
even the same litter. It is often thought, however, that
wild species do not var}^ sufficiently to bring about any
such change as this in the same time ; and though
naturalists are well aware that this is a mistake, it is only
recently that they have been able to adduce positive proof
of their opinion.
The Amount of Variation in JSorth American Birds. — ■
An American naturalist, Mr. J. A. Allen, has made elabor-
ate observations and measurements of the birds of the
United States, and he finds a wonderful* and altogether
unsuspected amount of variation between individuals of
the same species. They differ in the general tint, and in
the markings and distribution of the colours ; 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, width, thickness, and
curvature of the bill. These variations are very consider-
able, often reaching to one-sixth or one-seventh of the
average dimensions, and sometimes more. Thus Turdus
fuscescens (Wilson's thrush) varied in length of wing from
3"58 to 4'16 inches, and in the tail from 3"55 to 4*00 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 sialis (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 jDer
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 Dcndrosca coronata (the
yellow-cro^\^led warbler) the quills vary in jDroportionate
length, so that the 1st, the 2nd, the 3rd, or the 4th, is
sometimes long^est ; and a similar variation of the winof
involving a change of proportion between two or more of
the feathers is recorded in eleven species of birds. Colour
and marking vary to an equal extent ; the dark streaks on
the under surface of Melospiza melodia (the American
song-sparrow) being sometimes reduced to narrow lines.
CHAP. IV EVOLUTION THE KEY TO DISTRIBUTION 59
while ill other specimens they are so enlarged as to cover
the greater part of the breast and sides of the body, some-
times uniting on the middle of tlie breast into a nearly
continuous patch. In one of the small spotted wood-
thrushes, Turchcs fuscesccns, the colours are sometimes very
pale, and the markings on the breast reduced to indistinct
narrow lines, while in other specimens the general colour
is much darker, and the breast markings dark, broad, and
triangular. All the variations here mentioned occur be-
tween adult males, so that there is no question of differences
of age or sex, and the pair last referred to were taken at
the same place and on the same day.^
These interesting facts entirely support the belief in the
variability of all animals in all their parts and organs, to an
extent amply sufficient for natural selection to work with.
We may, indeed, admit that these are extreme cases, and
that the majority 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 occur, 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
specimens of each species, varying from 50 to 150 only, we
may be sure that the smaller variations we require must
occur in considerable numbers among the thousands or
millions of individuals 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 grou]) in which the mean or average
character prevailed with little variation, one in which the
character was greatly, and one in which it was little,
^ These facts arc 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 j\Iuseiim of Comparative Zoology at Harvard College, Cambridge,
]\Iassachusctts.
60 ISLA^'D LIFE
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 pre-
vailed was much more numerous than the extremes,
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 or-
dinary 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 gi'oup 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 existence
will lead to the continual suppression of the less perfectly
adapted extremes. But sometimes a species has a wide
range into countries which differ in physical conditions,
and then it often happens that one or other of the extremes
will predominate in a portion of its range. These form
local varieties, but as they occur mixed with the other
forms, they are not considered to be distinct species, al-
though they ma^^ differ from the other extreme form quite
as much as species often do from each other. ^
How New Species arise from a Variable Species. — It is
now very easy to understand how, from such a variable
species, one or more new species may arise. The peculiar
physical or organic conditions that render one part of the
area better adapted to an extreme form may become
intensified, and the most extreme variations thus having
the advantage, they will 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 the others ; while if the area should be cut in two
by subsidence or elevation, the conditions of the two parts
may be modified in opposite directions, so as to be each
adapted to one extreme form ; in which case the original
type will become extinct, being replaced by two species,
^ The great variation in wild animals is more fully discussed and
illustrated in the author's Darwinism (Chapter III.).
cHAf. IV EVOLUTION THE KF.V TO DISTRIBUTION 61
each formed by a combination ofcertain extreme characters
which had before existed in some of its varieties.
The changes of conditions which lead to such selection
of varieties are very diverse in nature, and new species
may thus be formed, diverging in many ways from the
origiucd stock. The climate may change from moist to
dry, or the reverse, or the temperature may increase or
diminish for long periods, in either case requiring a
corresponding change of constitution, of covering, of vege-
table or of insect food, to be met by the selection of
variations of colour or of swiftness, of length of bill or of
strength of claws. Again, competitors or enemies may
arrive from other regions, giving the advantage to such
varieties as can change their food, or by swifter flight or
greater wariness can escape their new foes. We may thus
easily understand how a series of changes may occur at
distant intervals, each leading to the selection and pre-
servation of a special set of variations, and thus what was
a single species may become transformed into a group of
allied species differing from each other in a variety of ways,
just as we find them in nature.
Among these species, however, there will be some wdiich
will have become adapted to very local or special condi-
tions, and will therefore be comparatively few in number
and confined to a limited area ; w^hile others, retaining the
more general characters of the parent form, but with some
important change of structure, will be better adapted to
succeed in the struggle for existence wdth other animals,
will spread over a wider area, and increase so as to become
common species. Sometimes these will acquire such a
perfection of organisation by successive favourable modi-
iieations that they Avill be able to spread greatly beyond
the range of the parent form. They then become what
are termed dominant species, maintaining themselves in
vigour and abundance over very wide areas, displacing
otlier species with Avhich they come into competition, and,
under still further changes of conditions, becoming the
parents of a new set of diverging species.
Definition and Origin of Genera. — As some of tlie most
important and interesting phenomena uf distribution relate
62 ISLAND LIFE part i
to genera 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 structural rather than a superficial nature. Species of
one genus usually differ from each other in size, in colour
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, &c. ; but they generally agree in the
form and structure 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 different genera.
We 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
variations as facilitate the change will be accumulated by
natural selection, and when they have become fixed in the
proportions most beneficial to the animal, we shall have the
first species of a new genus.
A creature which has been thus modified in important
characters will be a new type, specially adapted to fill a
new place in the economy of nature. It Avill almost cer-
tainly have arisen from an extensive or dominant species,
because only such are sufficiently rich in individuals to
afford an ample supply of the necessary variations, and it
will inherit the vigour of constitution and adaptability to
a wide range of conditions which gave success to its
ancestors. It Avill therefore have every chance in its favour
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 continents, 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
CHAP. IV EVOLUTION THE KEY TO DISTRIBUTION 63
epochs ; but the time will generally come when either
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 con-
tinue to maintain themselves in areas where they are
removed from the influences that exterminated their
fellows.
Cause of the Kdinction of Species, — There is good reason
to believe that the most effective agent in the extinction
of species is the pressure of other species, whether as
enemies or merely as competitors. If therefore any portion
of the earth is cut off from the influx of new or more
highly organised animals, we may there expect to find the
remains of groups which have elsewhere become extinct.
In islands which have been long separated from their
parent continents these conditions are exactly fulfilled, and
it is in such places that we find the most striking
examples of the preservation of fragments of primeval
groups of animals, often widely separated from each other,
owing to their having been preserved at remote portions of
the area of the once widespread parental group. There
are many other ways in which portions of dying out groups
may be saved. Nocturnal or subterranean modes of life
may save a species from enemies or competitors, and many
of the ancient types still existing have such habits. The
dense gloom of equatorial forests also aftbrds 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 Lepidosircn, or in sand
like the Amphioxus, the last being the most primitive of
all vertebrates ; while the Galeopithecus andTarsius of the
Malay islands and the potto of West Africa, survive amid
the hiohcr mammalia of the Asiatic and African continents
64 ISLAND LIFE
owing to their nocturnal habits and concealment in the
densest forests.
The Bise and Decay of Species a7id Genem.— 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 necessarily occupies a con-
tinuous area which gets larger and larger till it reaches a
maximum ; and we accordingly find that almost all exten-
sive groups are thus continuous. When decay commences,
and the group, ceasing to be in harmony with its environ-
ment, 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 therefore most
removed from the general type of the group, will have the
best chance of surviving, and these may exist at several
isolated points of the area once occupied by the Avhole
group. We may thus understand how the phenomenon of
discontinuous areas has come about, and we may be sure
that when allied species or varieties of the same species
are found widely separated from each other, they were
once connected by intervening forms or by each extending
till it overlapped the other's area.
Discontinuous Sioecific Areas, why Bare. — But although
discontinuous generic areas, or the separation from each
other of species wliose ancestors must once have occupied
conterminous or overlapping areas, is of frequent occur-
rence, yet undoubted cases of discontinuous specific areas
are very rare, except, as already stated, when one portion
of a species inhabits an island. A few examples among
mammalia have been referred to in our first chapter, but
it may be said that these are examples of the very com-
mon phenomenon of a species being only found in the
CHAP. IV EVOLUTION TTTE KEY TO DISTRIBUTION
station for which its organisation adapts it ; so that forest
or marsh or mountain animals are of course only found
where there are forests, marshes, or mountains. This
may be true, and when the separate forests or mountains
inhabited by the same species are not far apart there is
little that needs explanation ; but in one of the 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
territory, we are forced to the conclusion that it must
at some former period and under different conditions
have occupied a considerable portion of the intervening
area.
Among birds such cases of specific discontinuity are
very rare and hardly ever quite satisfactory. This may be
owing to birds being more rapidly influenced by changed
conditions, so that when a species is divided the two
portions almost always become modified into varieties
or distinct species ; while another reason may be that
their powers of flight cause them to occupy on the average
wider and less precisely defined areas than do the species
of mammalia. It will be interesting therefore to examine
the few cases on record, as we shall thereby obtain ad-
ditional knowledge of the steps and processes by which
the distribution of varieties and species has been brought
about.
Discontinuity of the Area of Parns 2'^alustris. — Mr. See-
bohm, who has travelled and collected in Europe, Siberia,
and India, and possesses extensive and accurate knowledge
of Pakncarctic birds, has recently called attention to the
varieties and sub-species of the marsh tit {Pcirus imlastris),
of which he has examined numerous specimens ranging
from England to Japan.^ The curious jDoint is that those
of Southern Europe and of China are exactly alike, while
all over Siberia a very distinct form occurs, forming the
sub-species P. horealisp- In Japan and Kamschatka other
1 See Ibis, 1879, p. 32.
^ In ^Ir. Seebohm's latest work, Birds of the Japanese Empire (1890),
he says, " Examples from North C'liina are indistinguisliable from thoso
obtained in Greece " (p. 82).
66 ISLAND LIFE pakt i
varieties are found, which have been named respectively
P.jcfponicus and P. camsc/iatkensis and another P. songarus
in Turkestan and MongoUa. 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 Farus horealis is a distinct species from
Pa.TUS pahistTis, as it is reckoned in Gray's Hand List of
Birds, and also in Sharpe and Dresser's Birds of Buroj^e,
then Paints x^cdustris has a most remarkable discontinuous
distribution, as shown in the accompanying 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 4,000 miles between them. If, how-
ever, 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. imlustris and P. horealis
are found together in Southern Scandinavia and in some
parts of Central Europe, and are said to differ somewhat
in their note and their habits, as well as in colouration.
Discontinuity of Biiibcriza schomiclus. — The other case
is that of our reed bunting (Bmberiza schceniclus), which
ranges over almost all Europe and Western Asia as far as
the Yenesai valley and North-west India. It is then
replaced by another smaller species, E. j^ctsseriiia , which
ranges eastwards 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. 'pyi^Tlvulina), but
Mr. Seebohm assures us that it is quite indistinguishable
from the European bird. Although the distance between
these two portions of the species is not so great as in the
last example, being about 2,000 miles, in other respects
the case is an interesting one, because the forms which
occupy the intervening space are recognised by Mr.
Seebohm himself as undoubted species.^
1 Ihis, 1879, p. 40. In his Birds of the Japanese Empire (1890), _ Mr.
Seebohm classes the Japanese and European forms as E. sclmniclus,
and thinks that their range is probably continuous across the two
continents.
CHAP. IV EVOLUTION THE KEY TO DISTRIBUTION
The Enrcfcan and Ja2i(incsc Jay>^. — Another case somo-
what resembling that of the marsh tit is afforded by the
European and Japanese ja3'S {Gamdn^ fflandarms and G.
jaj^cnicus). Our common Jay inhabits the wliole ofEurope
except the extreme north,, but is not known to extend any-
Avhere into Asia, where it is represented by several quite
distinct species. (See Map, Frontispiece.) But the great
central island of Japan is inhabited by a jay {G. japonicus)
which is very like ours, and was formerly classed as a sub-
species only, in which case our jay would be considered 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 species of jays which together range
over all temperate Europe and Asia, one which is so closely
allied to our English bird should be found at the remotest
possible point from it. Looking at the map exhibiting tlie
distribution of the several species, we can hardly avoid the
conclusion that a bird very like our jay once occupied the
whole area of the genus, that in various parts of Asia it
became gi'adually modified into a variety of distinct species
in the manner already explained, a remnant of the original
type being preserved almost unchanged in Japan, owing
probably to favourable conditions of climate and protection
from competing forms.
Supposed Exam2')lcs of Discontimiity among North
American Birds.— In North America, the eastern and
western provinces are so different in climate and vegetation,
and are besides separated by such remarkable physical
barriers — the arid central plains and the vast ranges of the
Kocky Mountains and Sierra Nevada, that we can hardly
expect to find species whose areas may be divided
maintaining their identity. Towards the north however
the above-named barriers disappear, the forests being
almost continuous from east to w-est, while the mountain
range is broken up by passes and valleys. It thus happens
that most species of birds which inhabit both the eastern
and w^estern coasts of the North American continent
have maintained their continuity towards the north,
while even when differentiated into two or luore alli<'(l
F 2
ISLAND LIFE
species their areas are often conterminous or over-
lapping.
Almost the only bird that seems to have a really discon-
tinuous range is the species of wren, Thryothoriis Imuickii,
of which the type form ranges from the east coast to
Kansas and Minnesota, while a longer-billed variety,
T. hcwicJcii sjnlurits, is found in the wooded parts of
California and as fal: north as Puget Sound. If ^ this
really represents the range of the species there remains a
gap of about 1,000 miles between its two disconnected areas.
Other cases are those of Vireo hellii of the middle United
States and the sub-fipecies lyusillus of California ; and of
the purple red-finch, CmyodacuspurpuTcus, with its variety
C. calif ornicus ; 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 that they
may somewhere become conterminous, though in the case of
the red- finches this does not seem likely to be the fact.
In a later chapter we shall have to point out some re-
markable 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 species, by two varieties of a species,
by two well-marked sub-species, and by two closely allied
but distinct species, are all different phases of one phenome-
non— the decay of ill-adapted, and their replacement by
better-adapted forms, under the pressure of a change of
conditions either physical or organic. We may now proceed
with our sketch of the mode of distribution of higher
groups.
Distrihution and Antiquity of Families. — Just as genera
are groups of allied species distinguished from all other
groups by some w^ell-marked structural characters, so
fainilies are groups of allied genera distinguished by more
marked and more important characters, wliich are generally
accompanied by a peculiar outward form and style of
colouration, and by distinctive habits and mode of life.
As a genus is usually more ancient than any of tlie species
of which it is composed, because during its growth and de-
velopment the original rudimentary species becomes sup-
CHAr. IV EVOLUTION THE KEY TO DISTRIBUTION
planted by more and mure perfectly adapted forms, so a
family is usually older than its component genera, and
during the long period of its life-history may have survixx-d
many and great terrestrial and organic changes. Many
families of the higher animals have now an almost world-
wide extension, or at least range over several continents ;
and it seems probable that all families which have survived
long enough to develop a considerable variety of generic
and specific forms have also at one time or other occupied
an extensive area.
Discontinuity a Proof of Antiquity. — Discontinuity will
therefore be an indication of antiquity, and the more widely
the fragments are scattered the more ancient we may
usually presume the parent group to be. A striking-
example is furnished by the strange reptilian fishes form-
ing the order or sub-order Dipnoi, which includes the
Lepidosiren and its allies. Only three or four living-
species are known, and these inhabit tropical rivers situated
in the remotest continents. The Zcpidosiren imradoxa is
only known from the Amazon and some other South
American rivers. An allied species, Lepidosiren annectcas,
sometimes placed in a distinct genus, inhabits the Gambia
in AVest Africa, while the recent discovery in Eastern
Australia of the Ceratodus or mud-fish of Queensland, adds
another form to the same isolated group. Numerous
fossil teeth, long known from the Triassic beds of this
country, and also found in Germany and India in beds of
the same age, agree so closely with those of the living
Ceratodus that both are referred to the same oenus. No
more recent traces of any such animal have been discovered,
but the Carboniferous Ctenodus and the Devonian Dip-
terus evidently belong to the same group, Avhile in Nortli
America the Devonian rocks have yielded a gigantic allied
form which has been named Hehodus by Professor Ne^\berr\■.
Thus an enormous range in time is accompanied by a very
wide and scattered distribution of the existing species.
Whenever, therefore, we find two or more living genera
belonging to the same family or order but not very closely
allied to each othei-, we may be sure that they are the
runimuits of a once extensive group of genera ; and if we
70 ISLAND LIFE
find them now isolated in remote parts of the globe, the
natural inference is that the family of which they are
fragments once had an area embracing the comitries in
which they are found. Yet this simple and very obvious
explanation has rarely been adopted by naturalists, who
have instead imagined changes of land and sea to afford a
direct passage from the one fragment to the other. If
there were no cosmopolitan or very wide-spread families
still existing, or e^^en if such cases were rare, there would
be some justification 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 Avhich 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 favour of the former continuity
of the group. We have also in many cases direct evidence
that this former continuity was effected by means of exist-
ing continents, while in no single case has it been shown
that such a continuity was impossible, and that it either
Avas or must have been effected by means of continents now
sunk beneath the ocean.
Conchtding Iicmarl's. — When w^riting on the subject of
distribution 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 the
gap between the isolated genera which in many cases now
alone exist ; while it is almost an axiom of " natural selec-
tion " that sucli 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, th.e known changes of
climate, and the actual powers of dispersal of the different
groups of animals, were such as would ha\'e enabled all the
now disconnected groups to have once formed parts of a
continuous series. Proofs uf 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 regards land animals renders it
CHAP. IV EYOLUTIOX TilE KEY TO DISTKIliTTIOX 71
unlikely that this proof will be forthcoming in the majority
of cases. The notion that if such animals ever cxistL-d
their remains would certainly be found, is a suj^erstitiun
which, notwithstanding the etibrts of Lyell and Darwin,
still largely j^revails among naturalists ; but until it is got
rid of no true notions of the former distribution of life upon
the earth can be attained.
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 IMammals— The Dispersal of Birds— The Dispersal of
Reptiles— The Dispersal of Insects— The Dispersal of Land MoUusca—
Great Antiquity of Land-shells— Causes favouring the Abundance of
Land-shells— The Dispersal of Plants— Special adaptability of Seeds for
Dispersal— Birds as agents in the Dispersal of Seeds— Ocean Curreiits as
agents in Plant Dispersal— Dispersal along Mountain-chains— Antiquity
of Plants as affecting their Distribution.
In order to understand the 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 Avldely over
the globe, while others are confined 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 geologiral or climatal changes which have
favoured or checked such migrations.
The first portion of the subject — that which relates to
the various modes by which organisms can pass over Avide
areas of sea and land — has been fully treated by Sir
Charles Lyell, by Mr. Darwin, and many other writers,
and it will only be necessary 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 tlie
ciiAi". V DISPERSAL OF ANIMALS AXD PLANTS
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 cliniatal
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. 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 ventuie to hope may serve as the foundation for a better
comprehension of these intricate problems. The four
chapters wdiich follow this are devoted to a full examin-
ation of these profoundly interesting and important
questions, after wdiich w^e shall enter upon our special
inquiry — the nature and origin of insular faunas and
floras.
The Ocean as a Barrier to tJie Dispersal of Mcunrn ah. — A
wide extent of ocean forms an almost absolute barrier to
the dispersal of all land animals, and of most of those
wdiich are aerial, since even birds cannot fly for thousands
of nu'es without rest and without food, unless they are
aquatic b;rds 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 Imd 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 w^ould certainly endeav-
our 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 nianiniali;^.
74 ISLAND LIFE
Deer also swim well, but there is no reason to believe that
they would venture out of sight of land. With the smaller,
and especially with the arboreal mammalia, there is a
much more effectual 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
Philippine Islands similar rafts Avith trees growing on them
liave been seen after hurricanes ; and it is easy to under-
stand how, if the sea were tolerably calm, such a raft might
be carried along by a current, aided by the wind acting on
the trees, till after a passage of several weeks it might
arrive safely on the shores of some land hundreds of miles
away from its starting-point. Such small animals as
squirrels and field-mice might have been carried away on
the trees which formed part of such a raft, and might thus
colonise a new island ; though, as it would require a pair of
the same species to be thus conveyed at the same time, such
accidents Avould no doubt be rare. Insects, however, and
land-shells would almost certainly be 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 sucli causes, we
cannot suppose that they have been effective in the
dispersal of mammalia as a whole ; and whenever we find
that a considerable number of the mammals of two
countries exhibit distinct marks of relationship, Ave 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. But a considerable number of identical
mammalian families and even genera are actually found in
all the great continents, and the present distribution of
land upon the globe renders it easy to see how they have
been able to disperse themselves so widely. All the great
land masses radiate from the arctic regions as a common
centre, the only break being at Behrings Strait, Avhich is
so shallow that a rise of less than a thousand feet would
DISPERSAL OF ANIMALS AND PLANTS
o
form a broad isthmus connecting Asia and America as far
south as the parallel of 00° N. Continuity of land tliere-
fore may be said to exist already for all parts of the world
(except Australia and a number of large islands, which
will be considered separately), and we have thus no
difficulty in the way of that former wide diffusion of many
groups, which wc maintain to be the only explanation of
most anomalies of distribution other than such as may be
connected with unsuitability of climate.
The DUi^cTsal of Birds. — Wherever mammals can mi-
j'rate other vertebrates can generally follow with even
greater facility. Birds, having the power of flight, can
pass over wide arms of 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 exceptional 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 Disjicrsal of Ilcpiilcs. — ReiJtiles appear at lirst
sight to be as much dependent on land for their dispersal
as mammalia, but they possess two peculiarities which
favour their occasional transmission across the sea — the
one being their greater tenacity of life, the other their
oviparous mode of rei:>roduction. 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 tliat it captured some sheep before it was
killed. The island is nearly two hundred miles from
Trinidad and the coast of South America, whence the
reptile almost certainly carne.^ Snakes are, however,
comparatively scarce on islands far from continents, but
lizards are often abundant, and though tliese might also
tra\'el on floating trees, it seems more jirobable that there
' Lyi'ir.s rriacipks of (Jcuh<jij, ii,, p. oGU.
76 ISLAND LIFE
is some as yet unknown mode by which their eggs are
safely, though joerhaps very rarely, conveyed from island
to island. Examples of their peculiar distribution will be
j-iven when we treat of the fauna of some islands in which
o
they abound.
The Dispersal of Aniiohihia and Fresh-iuatcr 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 anotlier ad-
vantage over reptiles in being capable 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
latitudes which has been the chief agent in producing the
general uniformity in the animal productions of tlie globe.
Some genera of Batrachia have almost a world-wide dis-
tribution ; Avhile the tailed Batrachia, such as the newts
and salamanders, are almost entirely confined to the
northern hemisphere, some of the genera spreading over
the whole of the north temperate zone. Fresh-water
fishes have often a very wide range, the same species
being sometimes found in all the rivers of a continent.
This is no doubt chiefly due to the want of permanence in
river basins, especially in their lower jDortions, Avhere
streams belonging to distinct systems often approach each
other and may be made to change their course from one
to the other basin by very slight elevations or depressions
of the land. Hurricanes and water-spouts also often carry
considerable quantities of water from jDonds 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 same genera. The exce2:>tioiis are in
the colder regions of the earth, where the transporting power
of ice may have come into play. High ranges of moun-
tains, if continuous for long distances, rarely have the
same species of fish in the rivers on their two sides.
Wliere exceptions occur, it is often due to tlie great
CHAP. V DISPERSAL OF ANIMALS AND PLANTS 77
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
impassable to more recent types. Yet another and morc^
efficient explanation of the distribution of this group of
animals is the fact that many families and genera inhabit
both fresh and salt water ; and there is reason to believe
that many of the fishes now inhabiting the tro^Dical rivers
of both hemispheres have arisen from allied marine forms
becoming gradually modified for a life in fresh Avater.
By some of these various causes, or a combination of them,
most of the facts in the distribution of fishes can be
explained without much difficulty.
The Dis2Jersal of Insects. — In the enormous group of
insects the means of dispersal among land animals reach
their maximum. Many of them have great jDowers of
flight, and from their extreme lightness they can be carried
immense distances by gales of wind. Others can survive
exposure to salt water for many days, and may thus be
floated long distances by marine 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 are floated. Another important 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 hemisphere 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 tliis
wonderful restriction to limited areas is, undoubtedly, the
extreme specialisation of most insects. They have become
so exactly adapted to one set of conditions, that when
ISLAXD LIFE part i
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
whom 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
combination 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 explanation of the
many anomalies we meet with in studying their distribu-
tion.
The Dispersal of Land Mollusca. — The only other group
of animals we need now refer to is that of the air-breathing
mollusca, commonly called land-shells. These are almost
as ubiquitous as insects, though far less numerous ; and
their wide distribution is by no means so easy to explain.
The genera have usually a very wide, and often a cosmo-
politan range, while the species are rather restricted, and
sometimes wonderfully so. Not only do single islands,
however small, often possess peculiar species of land-shells,
but sometimes single mountains or valleys, or even a
particular mountain side, possess species or varieties found
nowhere else upon the globe. It is pretty certain that
they have no means of passing over the sea but such as are
very rare and exceptional. Some which possess an
operculum, or which close the mouth of the shell with a
diaphragm of secreted mucus, may float across narrow
arms 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 motion.
1 ]\Ir. Darwin found that the large Helix poraaiia lived after immersion
in sea-water for twenty days. It is hardly likely that this is the extreme
limit of their powers of endurance, but even this would allow of their being
lloated many hundred miles at a stretch, and if we suppose the shell to be
partially protected in the crevice of a log of wood, and to be thus out of
CHAP. V DISPERSAL OF ANIMALS AND PLANTS 79
their powers of voluntary dispersal, even on land, arc \'erv
limited, and this will explain the extreme restriction of their
range in many cases.
CrTcat Antiquity of Land-Shells.— T\\q clue to the almost
universal distribution of the several families and of many
genera, is to be found, however, in their immense antiquity.
In the Pliocene and Miocene formations most of the land-
shells are either identical with living species or closely
allied to them, while even in the Eocene almost all are of
living genera, and one British Eocene fossil still lives in
Texas. Strange to say, no true land-shells have been
discovered in the Secondary formations, but they must
certainly have abounded, for in the far more ancient
Palaeozoic coal measures of Nova Scotia two species
belonging to the living genera Pupa and Zonites have been
found in considerable abundance.
Land-shells have therefore survived all the revolutions
the earth has undergone since Palaeozoic times. They
have been able to spread slowly but surely into every land
that has ever been connected with a continent, while the
rare chances of transfer 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 islands of the mid-ocean
have thus become stocked with them, though the varietv
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 Favouring the Alundanec of Zavd-SIalls. — The
abundance and variety of land-shells is also, more than that
of any other class of animals, dependent on the nature of
the surface and the absence of enemies, and where these
conditions are favourable their forms are wonderfully
luxuriant. The first condition is the presence of lime in
the soil, and a broken surface of country with nuich rugged
water in calm weatlier, the distance miglit extend to a thousand miles or
more. The eggs of fresh-water mollusca, as well as the young animals, are
known to attach themselves to the feet of aquatic birds, and this is probably
the most efficient cause of their vcrv wide diffusion.
80 ISLAND LIFE
rock offering crevices for concealment and hybernation.
The second is a limited bird and mammalian fauna, in
which such species as are especially shell-eaters shall be
rare or absent. Both these conditions are found in certain
large islands, and pre-eminently in the Antilles, which
possess 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 gi'oup of
animals whatever, but which is perhaps explained by the
considerations now suggested.
The DisiKTsal of Plants.— T\\e ways in which plants are
dispersed over the earth, and the special facihties they often
possess for migration have been pointed out by eminent
botanists, and a considerable space might be occupied in
p-iving a summary of what has been written on the subject.
In tlie 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 be advisable to adduce any
special facts when they are required to support the argu-
ment in particular cases. A few general remarks only will
therefore be made here.
Bioccial AdaptaUliUj of Seeds for Dispersed. — Plants pos-
sess many great advantages over animals as regards the
power of dispersal, since they are all propagated by seeds or
spores, which are hardier than the eggs of even insects, and
retain their vitality for a much longer time. Seeds may
lie dormant for many years and then vegetate, while they
endure extremes of heat, of cold, of drought, or of moisture
which would almost always be fatal to animal germs.
Among the causes of the dispersal of seeds De Candolle
enumerates the wind, rivers, ocean currents, icebergs, birds
and other animals, and human agency. Great numbers 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 enable them to be
carried enormous distances. 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 inconspicuous most seeds are. Supposing every
cHAi'. V DISPERSAL OF ANIMALS AND PLANTS 81
year a million seeds were brought by tlie wind to the
British Isles from the Continent, this would be only ten
to a square mile, and the observation of a life-time might
never detect one ; yet a hundredth part of this number
would serve in a few centuries to stock an island like
Britain with a great variety of continental plants.
When, however, we consider the enormous quantity of
seeds produced by plants, that great numbers of these are
more or less adajDted 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.
Such 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 powers of flight could have
effected.
Birds as Agents iii the Dispersal of Plants. — Birds are
undoubtedly important agents in the dispersal of plants
over wide spaces of ocean, either by swallowing fruits and
rejecting the seeds in a state fit for germination, or by the
seeds becoming attached to the plumage of ground-
nesting birds, or to the feet of aquatic birds embedded in
small quantities of mud or earth. Illustrations of these
various modes of transport will be found in Chajiter XII.
when discussino- the orioin of the flora of the Azores and
Bermuda.
Ocean-currents as Agents in Plant-clispersal. — Ocean-cur-
rents 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 experi-
ments have been collected proving that seeds may some-
times be carried in this way many thousand miles and
afterwards germinate. Mr. Darwin made a series of in-
teresting experiments on this subject, some of which will
be given in the chapter above referred to.
Dispersed along Mountain Chains. — These \arious modc.'s
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
G
82 ISLAND LIFE
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 explained
by' such causes alone. It is here that transmission along
mountains chains has ^^robably been effective; and the
exact mode in which this has occurred is discussed in
Chapter XXIII., where a considerable body of facts is
given, showing that extensive migrations may be effected
by a succession of moderate steps, owing to the frequent
exposure of fresh surfaces of soil or cUbris on mountain
sides and summits, offering stations on which foreign
plants can temporarily establish themselves.
Antiquity of Plants as affecting their Distribution.— ^e
have already referred to the importance of great antiquity
in enabling 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. Rich floras have
been discovered in the Miocene, the Eocene, and the Upper
Cretaceous formations, and these consist 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
survived great geological, geographical, and climatal
changes; and this fact, combined with the varied and
wonderful powers of dispersal many of them j^ossess, ren-
ders it far less difficult to understand the examples of wide
distribution of the genera and species of plants than in the
case of similar instances among animals. This subject
will be further alluded to when discussing the origin of
the New Zealand flora, in Chapter XXII.
CHAPTER VI
GEOGRAPHICAL AND GEOLOGICAL CHANGES : THE
PERMANENCE OF CONTINENTS
Changes of Land and Sea, their Xature 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 — Eti'ect of Continental
Changes on the Distribution of Animals — Changed Distribution proved
by the Extinct Animals of Ditferent Epochs — Summary of Evidence
for the general Permanence of Continents and Oceans.
The clianges of land and sea which have occurred in par-
ticular cases will be described when we discuss the origin
and relations 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 wu
can hardly exclude the surfaces occupied by volcanic and
fresh-Avater 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 inference thai
when the present continents were under water there must
G '1
84 ISLAND LIFE
have been other contments 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 Avhole
o-eological epochs, shift their positions entirely in the course
of ao^s. "^ Mr. T. Mellard Reade, late President of the
Geological Society of Liverpool, so recently as 1878, says : —
" White believing that the ocean-depths are of enormous
age, it is imposs'ible 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 simi-
lar to that of Europe, and this could not have happened
without littoral continuity, yet there are depths of 1,500
fathoms between these continents."- It is certainly strange
that a geologist should not remember the recent and long-
continued warm climates of the Arctic regions, and see
that a connection of Northern Europe by Iceland with
Greenland and Labrador over a sea far less than a thousand
fathoms deep would furnish the "littoral continuity" re-
quired. Again, in the same pamphlet Mr. Reade says :— " It
can be mathematically 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 witli respect to the sea were confined within
limits near the present continents, the results would have
been a gradual diminution instead of develoj)ment of the
calcareous rocks. To state the case in common language,
the calcareous portion of the rocks would have been
washed out during the mutations, the destruction and re-
deposit of the continental rocks, and eventually deposited
in the depths of the immutable sea far from land.
Immense beds of limestone would now exist at the bottom
of the ocean, Avhile the land Avould be composed of sand-
stones and argillaceous shales. The evidence of chemistry
thus confirms tlie inductions drawn from the distribution
of animal life u2)on the globe."
1 Vrmciplcs of Gcoloyij, 11th Ed., A'ol, I., p. 258.
•- Ou Limestoue as an ludcx of Geological Time.
CHAP. Yi GEOGRAPHICAL AXD GEOLOGICAL (IIAXgES
So far from this being a "mathematical demonstration,"
it appears to me to be a complete misiuterprctntion of
the facts. Animals did not create the lime which they
secrete from the sea-water, and therefore we liave every
reason to believe that the inorganic sources whicli origin-
ally supplied it still keep up that supply, though perhaps
in diminished quantity. Again, the great lime-secreters —
corals — work in water of moderate dei^th, that is, near
land, while there is no proof whatever that there is any
considerable accumulation of limestone at the bottom oi
the deep ocean. On the contrary, the fact ascertained by
the Challenger, that beyond a certain deptli the
" calcareous " ooze ceases, and is replaced b}^ red and grey
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 prevented. As
to the increase of limestones in recent as conij^.arcd with
older formations, it may be readily explained by two
considerations : in the first place, the growth and develoj)-
ment of the land in longer and more complex shore lines
and the increase of sedimentary over volcanic formations
may have offered more stations favourable to the growth
of coral ; while the solubility of limestone in rain-water
renders the destruction of such rocks more rapid than that
of sandstones and shales, and would thus, by supplying
more calcareous matter in solution for secretion by lime-
stone-forming organisms, lead to their comparative
abundance in later as compared with earlier formations.
However weak we ma}^ consider the above-quoted argu-
ments 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 rapidly gaining ground among
students of earth-history.
Slmre DcprmU avd Stralified JiOcJcs. — If we go round tin-
shores of any of our continents we shall almost always find a
considerable belt of shallow water, meaning thereby water
from 100 to 1.50 fathoms deep. Tlio distance horn the
86 ISLAND LIFE part i
coast line at which such depths are reached is seldom less
than twenty miles, and is very frequently more than a
hundred, Avhile in some cases such shallow seas extend
several liundred miles from existing continents. The gi^eat
depth of a thousand fathoms is often reached at thirty
miles from shore, but more frequently at about sixty or a
hundred miles. Eound the entire African coast for
example, this depth is reached at distances varying from
forty to a hundred and fifty miles (except in the Red Sea
and the Straits of Mozambique), the average being about
eighty miles.
Now the numerous specimens of sea-bottoms collected
during the voyage of the Challenger show that true shore-
deposits — that is, materials denuded from the land and
carried down as sediment by rivers — are almost ahvays
confined within a distance of 50 or 100 miles of the coast, the
finest mud only being sometimes carried 150 or rarely 200 ^
miles. As the sediment varies in coarseness and density it
is evident that it will sink to the bottom at unequal
distances, the bulk of it sinking comparatively near shore,
while only the very finest and almost impaljDable mud will
be carried out to the furthest limits. Beyond these limits
the only deposits (with few exceptions) are organic, con-
sisting of the shells of minute calcareous or siliceous
organisms with some decomposed pumice and volcanic dust
which floats out to mid-ocean. It follows, therefore, that
by far the larger part of all stratified deposits, especially
those which consist of sand or pebbles or any visible frag-
ments of rock, must have been formed Avithin 50 or 100
miles of then existing continents, or if at a greater distance,
in shallow^ inland seas receiving deposits from more sides
than one, or in certain exceptional areas where deep ocean
currents carry the d^hris of land to greater distances.^
^ In his Preliminary Report on Oceanic Bcposit, Mr. Murray says : — "It
has been found that the deposits taking place near continents and islands
have received their chief characteristics from the presence of the debris
of adjacent lands. In some cases these deposits extend to a distance of
over 150 miles from the coast." {Procecdinqs of the Royal Societv,
YoL XXI Y. p. 519.)
' ' The materials in suspension appear to be almost entirely deposited
within 200 miles of the land." [Proceedings of the Royal Society of Edin-
burgh, 1876-77, p. 253.)
CHAP. VI GEOGRAPHICAL AND GEOLOGICAL CHANGES 87
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 sliales, which
must, as we have seen, have been dei:)osited within
a comparatively short distance of a sea-shore. Sir
Archibald Geikie says : — " Among the thickest masses of
sedimentary rock — those of the ancient Pakeozoic systems
— no'features recur more continually than the alternations
of different sediments, and the recurrence of surfaces
covered with well-preserved ripple-marks, trails and
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 to])
of formations, which reach a thickness of several thousand
feet. They can be interpreted only in one way, viz., that
the formations in question began to be laid down in shallow
water ; that during their formation the area of deposit
gradually subsided for thousands of feet; yet that the rate
of accumulation of sediment kept pace on the whole wuth
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
statement applies to the more recent as well as to the more
ancient formations, and concludes — ''In short, the more
attentively the stratified rocks of the earth are studied, the
more striking becomes the absence of any formations among
them, which can legitimately be considered those of a deep
sea. They 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. Wo
find them stretching across the country in one general
direction, in belts of no sfreat width thouo^h 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
^ Geographical Evolution. {Proceedings of the Royal Geographical Society..
1879, p. 426.)
88 ISLAND LIFE part i
from the fUhris of which they were originally formed.
Again quoting Sir Archibald Geikie :— " The materials car-
ried down to the sea would arrange themselves then as they
do still, the coarser portions nearest the shore, the finer silt
and mnd furthest from it. From the earliest geological
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 nature 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 igne-
ous or metamorphic rocks, it follows that at one period or
another each part of the continent has been under the sea,
but at the same time not far from the shore. Geologists
now recognise two kinds of movements by which the
deposits so formed have been elevated into dry land-
in the one case the strata remain almost level and
undisturbed, in the other they are contorted and crumpled,
often to an enormous extent. The former often prevails in
plains and plateaus, wdiile the latter is almost always found
in the great mountain ranges. We are thus led to picture
the land of the globe as a flexible area in a state of slow
but incessant change ; the changes consisting of low
undulations w^hich creep over the surface so^ as to elevate
and depress limited portions in succession without percep-
tibly affecting their nearly horizontal position ; and also of
intense lateral compression, supposed to be produced by
partial subsidence along certain lines of weakness in the
earth's crust, the effect of which is to crumple the strata
and force up certain areas in great contorted masses, which,
when carved out by subaerial denudation into peaks and
valleys, constitute our great mountain systems.^ In this
1 Professor Dana was, I believe, tlie first to point out that the regions
which, after long undergoing subsidence and accumulating vast piles of
sedimentary deposit have been elevated into mountain ranges, thereby
become stiff and unyielding, and that the next depression and subsequent
upheaval will be situated on one or the other sides of it ; and he has shown
that, in North America, this is the case with all the mountains_ of the
successive geological formations. Thus, depressions, and elevations of
extreme slowness but often of vast amount, have occurred successively in
CHAP. VI GEOGRAPHICAL AND GEOLOGICAL CHANGES 89
way every part of a continent may again and again liavc
sunk beneath the sea, and yet as a Avhole may never have
ceased to exist as a continent or a vast continental archi-
pelago. And, as subsidence will always be accompanied
by deposition, of sediments from the adjacent land, piles r»f
marine strata many thousand feet thick may have been
formed in a sea which was never ver}^ deep, by means of a slow
depression either continuous or intermittent,or through alter-
nate subsidences and elevations, each of moderate amount.
Supposed Oceanic Formations ; — the Origin, of Chall-. —
There seems very good reason to believe that few, if any, of
the rocks known to geologists corresj^ond exactly to the do-
jDosits now forming at the bottom of our great oceans. The
white oceanic mud, or Globigerina-ooze, found in all the gTcat
oceans at depths varying from 250 to nearly 3,000 fathoms,
and almost constantly in dej^ths under 2,000 fathoms, has,
however, been supposed to be an exception, and to corre-
spond exactly to our white and grey 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 chieHy on account of the similarity of the minute
organisms found to compose a considerable proportion 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 minute organisms whose nature is doubtful,
called coccoliths and discoliths, are also found in both
formations, while there is a considerable general resem-
blance between the higher forms of life. Sir Wyville
Thomson tells us, that — " Sponges are abundant in both,
and the recent chalk-mud has yielded a large number of
examples of the group porifcra ritrca, Avhich find their
nearest representatives among the Ventriculites of the
white chalk. The echinoderm fauna of the deeper parts of
restricted adjacent areas ; and tlic edect lias been to l)rin<; each portion in
succession beneath the ocean but always bordered on one or botli sides l»y
the remainder of the continent, from the denudation of which tlie deposits
are formed wliich, on tlie subseiiuent uplieaval, become mountain raiiijes.
{Manual of Geology, 2nd Ed., p. 7r»l.)
90 ISLAND LIFE
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 genns Cidaris are numerous ; some remark-
able flexible forms of the Diademidse seem to approach
Echinothuria " ^ Now, as some explanation of the origin
of chalk had long been desired by geologists, it is not
surprising that the amount of resemblance shown to exist
between it and some kinds of oceanic mud should have
been at once seized upon, 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 Southern oceans.
But there are several objections to this view which seem
fatal to its acceptance. In the first place, no specimens of
Globigerina-ooze from the deep ocean-bed yet examined
agree even approximately with chalk in chemical compo-
sition, only containing from 44 to 79 per cent, of carbonate
of lime, Avith 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 car-
bonate of lime, and a very minute quantity of alumina and
silica. This large proportion of carbonate of lime implies
some other source of this mineral, and it is probably to be
found in the excessively fine mud produced by the decom-
position 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 resembling chalk in colour,
texture, &c. ; while in several growing reefs a similar
formation of modern chalk undistinguishable from the
ancient, was observed.^ Sir Charles Lyell well remarks
1 Kaiurc, Vol. II,, p. 297.
2 Sir W. Thomson, Foijagc of Challenger, Vol. 11. , p. 374.
2 The following is the analysis of the chalk at Oahu :—
Carbonate of Lime 92-800 per cent.
Carbonate of Magnesia 2 'SSS
Alumina 0-250
Oxide of Iron 0-543
Silica 0-750
Phosphoric Acid and Fluorine 2-113
"Water and loss — 1-148
cirAP. VT GEOr^RAPHirAL AXD riEOLOCK'AT. CIIAXCKS !'l
that the pure calcareous mud produced by tlie decompo-
sition of tlio shelly coverings of mollusca and zoophytes
would be much lighter than argillaceous or nrennceous mud,
and being thus transported to greater distances would bo
completely separated from all impurities.
Now the Globigerina:^liave been shown by tlie Cluillrngcr
explorations to abound in all moderately warm seas ; living
This chalk consists simply of comminuted corals and shells of tlio reef.
It has been examined microscopically and found to be destitute of the
minute organisms abounding in the chalk of England. {Geology of the
United States E.rpJonng Expedition, p. 150.) i\Ir. Guppy also found
chalk-like coral limestones containing 95 p.c. of carbonate of lime in tlie
Solomon Islands.
The absence of Glohigerince is a local phenomenon. They are quite
absent in the Arafura Sea, and no Globigerina-ooze was found in any of
the enclosed seas of the Pacific, but with these exceptions the Glohigcrino:
"are really found all over the bottom of the ocean." (]\Iurray on Oceanic.
'De^o?,\i&— Proceedings of Rayed Society, Vol. XXIV., p. 523.)
The above analysis shows a far closer resemblance to chalk than that
of the Globigcrinet-ooze. of the Atlantic, four specimens of wliicli given by
Sir ^y. Thomson {Foyetgc of the Challenger Vol. II. Appendix, pp. 374-
376, Nos. 9, 10, 11 and 12) from the mid- Atlantic, show the following
I)ro portions : —
Carbonate of Lime 43-93 to 79-17 per cent.
Carbonate of Magnesia 1-40 to 2-58
Alumina and Oxide of Iron. 6-00? to 32-98
Silica 4-60 to 11-23 "
In addition to the above there is a quantity of insoluble residue consist-
ing of small particles of sanidine, augite, hornblende, and magnetite,
supposed to be the product of volcanic dust or ashes carried citlim- in tlic
air or l)y ocean currents. This volcanic matter amounts to from 4-60
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 different, and that it was
deposited far more rapidly than the oceanic ooze.
The following analysis of chalk by Mr. D, Forl>es will show the diHcrcnce
between the two formations : —
Grey Clialk, Wliite Chalk,
Folkestone. Shoreham.
Carbonate of Lime 94*09 98-40
Carbonate of ]\Iagncsia 0-31 0 "OS
Alumina and Phosphoric Acid .. a trace 0*42
Chloride of Sodium 1'29 —
Insoluble debris 3-61 I'lO
(From Quarterly Journal of the Geological Society, Vol. XXVII.)
The large proportion of carbonate of lime, and the very small quantity
of silica, alumina, and insoluble debris, at once distinguish true chalk from
the Globigerina-ooze of the deep ocean bed.
92 ISLAND LIFE
both at the surface, at various depths in the water, and at
the bottom. It was long thought that they were surface-
dwellers only, and that their dead tests sank to the bottom,
producing the Globigerina-ooze in those areas where other
deposits were absent or scanty. But the examination of
the whole of the dredcrings and surface-gatherings of the
Chalkngcr 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
hitter 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 Globigerin?e
are abundant in bottom dredgings, but are never found on
the surface in the towing-nets.^ These organisms then
exist almost universally where the waters are pure and are
not too cold, and they would naturally abound most where
the diffusion of carbonate of lime both in suspension and
solution afforded them an abundant supply of material for
their shelly coverings. Dr. Wallich believes that they
flourish best where the warm waters of the Gulf Stream
bring organic matter from which they derive nutriment,
since they are wholly wanting in the course of the Arctic
current between Greenland and Labrador. Dr. Carpenter
also assures us that they are rigorously limited to warm
areas ; but Mr. Brady says that a dwarf variety of Globi-
gerina was found in the soundings of the North Polar
Expedition in Lat. 83° 19' N.
Now with regard to the depth at which our chalk was
formed, we have evidence of several distinct kinds to show
that it was not profoundly oceanic. Mr. J Murray, in the
report already referred to, says : '"' The Globigerina-oozes
which we get in shallow water resemble the chalk much
more than those in deeper water, say over 1,000 fathoms."^
This is important and weighty evidence, and it is supported
in a striking manner by the nature of the molluscan fauna
of the chalk. Dr. Gwyn Jeffreys, one of our greatest
^ Notes on Reticularian Rhizopoda ; iwMicroscopicalJovrnal, Vol. XIX.,
New Series, p. 84.
2 Procecdivg.'} of the Royal Society, Vol. XXIY. p. .582.
CHAP. VI GEOGRAPHICAL AND GEOLOGICAL CHANGES 93
authorities on slic41s, 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
series of genera which are found in the Chalk formation,
seventy-one in number, he declared that they are all com-
paratively shallow-water forms, many living at depths not
exceeding 40 to 50 fathoms, while some are confined to
still shallower waters. Even more important is the fact
that the genera especially characteristic of tlie deep
Atlantic ooze — Leda, A'erticordia, Neiera, and the Bulla
family — are either very rare or entirely wanting in the
ancient Cretaceous deposits.^
Let us now see how the various facts already adduced
will enable us to explain the peculiar characteristics of the
chalk formation. Sir Charles Lyell tells us that "pure
chalk, of nearly uniform aspect and composition, is met
with in a north-west and south-east direction, from the
north of Ireland to the Crimea, a distance of about 1,500
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 wdthin which true chalk is found,
though it is by no means continuous. It probably implies,
however, 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 Scan-
dinavian highlands, extending to Northern Germany and
Xorth-western Russia, where Palaeozoic and ancient
Secondary rocks have a wide extension, though now
partially concealed by late Tertiary deposits ; Avhile un the
south it appears to have been limited by land extending
through Austria, South Germany, and the south of France,
as shown in the map of Central Europe during the
Cretaceous period in Professor Heer's Friiiiccal World of
Switzerland, p. 175. To the north the sea may have had
^ Stiu Presidential Addre.sb in Sect. D. of British Associiitiou at Plvmuutli,
1877.
ISLAND LIFE
an outlet to the Arctic Ocean between 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 expected,
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 joure sands and sandstones, charac-
terised 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 deposits containing
the remains of land-plants in abundance, indicating a rich
and varied flora.
Now all these facts are totally opposed to the idea of
anything like oceanic conditions having prevailed in
Europe during the Cretaceous period ; but they are quite
consistent with the existence of a great Mediterranean sea
of considerable depth in its central portions, and occupying
either at one or successive periods, the whole area of the
Cretaceous formation. We may also note that the Maes-
tricht beds in Belgium and the Faxoe chalk in Denmark
are both highly coralline, the latter being, in fact, as com-
pletely comj^osed of corals as a modern coral-reef ; so that
we have here a clear indication of the source whence the
white calcareous mud was derived which forms the basis
of chalk. If we suppose that during this period the
comparatively shallow sea-bottom between Scandinavia
and Greenland was elevated, forming a land connection
between these countries, the result would be that a large
23ortion of the Gulf Stream would be diverted into the
inland European sea, and would bring with it that abun-
dance of Globigerina3, and other Foraminifera, 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 con-
ditions for the production of the true chalk, as well as the
other members of the Cretaceous formation. The products
cHAr. Yi GEOGKAPHICAL AND GEOLOGICAL CHANGES 95
of the denudation of its shores and islands would form the
various sandstones, marls, and clays, which would be
deposited almost wholly within a few miles of its coasts ;
while the great central sea, perhaps at n(j time more than
a few thousand feet deep and often much less, would
receive only the impalpable mud of the coral-reefs and the
constantly falling tests of Foraminifera. These would
imbed and preserve for us the numerous echinoderms,
sponges, and mollusca, which lived upon the bottom, the
fishes and turtles which swam in its waters, and some-
times the winged reptiles that flew overhead. The abun-
dance of ammonites, and other cephalopods, in the chalk,
is another indication that the water in which they lived
was not very deep, since Dr. S. P. Woodward thinks that
these organisms were limited to a dej^th of about thirty
fathoms.
The best example of the modern formation of chalk is
perhaps to be found on the coasts of sub-tropical North
America, as described in the following passage : —
" The observations of Pourtales show that the steep
banks of Bahama are covered with soft white lime mud.
The lime-bottom, which consists almost entirely of Poly-
thalamia, covers in greater depths the entire channel of
Florida. This formation extends without interruption
over the whole bed of the Gulf Stream in the Gulf of
Mexico, and is contiimed along the Atlantic coast of
America. The commonest genera met with in this
deposit are Globigerina, Rotalia cultrata in large numbers,
several Textilariie, Marginulinse, &c. Beside these, small
free corals, Alcyonidae, Ophiura^, Mollusca, Crustacea, small
fishes, &c., 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 Avliich seems to have
been altogether overlooked by those who suppose that a
deep and 02)en island-studded ocean occujjied the place of
Eunjpe in Cretaceous times. No fact is more certain than
the considerable break, indicative of a great lapse of time,
intervening between the Cretaceous and Tertiary for-
^ Gcolujical Muya-.i/ic, IS 71, p. -12G,
96 ISLAND LIFE
mations. A few deposits of intermediate 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. Nov/, what does this gap mean ?
It implies that when the deposition of the various Creta-
ceous beds of EuroiDO 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
Avas 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
Avhicli we actually find Cretaceous deposits, or where we
have good reason to believe they have existed ; and even
these need not have been all under water at the same
time.
The several considerations now adduced are, I think,
sufficient to show that the view put forth by some natural-
ists (and which has met with a somewhat hasty acceptance
by geologists) that our white chalk is an oceanic formation
strictly comparable with that now forming at depths of a
thousand fathoms and upwards in the centre of the
Atlantic, gives a totally erroneous idea of the actual con-
dition of Europe during that period. Instead of being a
wide ocean, with a few scattered islands, comparable to
some parts of the Pacific, it formed as truly a portion of the
great northern continent as it does now, although the in-
land seas of that epoch may have been more extensive
and more numerous than they are at the j^resent day.^
^ In liis lectiu'c ou Gcoyraphical EwliUioii (which waii published iil'ter the
greater part of this chapter had been written) Sir Archibakl Geikie expresses
views in complete accordance Avith those here advocated. He says : — " The
next long era, the Cretaceous, was more remarkable for slow accumulation
of rock under the sea than for the formation of new land. During that
time the Atlantic sent its waters across the whole of Europe and into Asia.
But they were probably nowhere mure than a few hundred feet deep over
CHAP. Yi GEOGRAPHICAL AND GEOLOGICAL CHANGES 97
Fresh'VMtcr and Shore Deposits as Proving the Permanence
nf Continents. — The view liere maintained, that all known
marine deposits have been formed near the coasts of con-
tinents and islands, and that our actual continents have
been in continuous existence under variously modified
forms during the whole period of known geological history,
is further supported by another and totally distinct series
of facts. In almost every period of geology, and in all the
continents which have been well examined, there are found
lacustrine, estuarine, or shore deposits, containing the
remains of land animals or plants, thus demonstrating 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 liave such deposits
with remains of land-animals, or plants, in Devonshire and
Scotland, in France, Switzerland, Germany, Croatia,
Vienna, Greece, North India, Central India, Burmah,
North America,' both east and west of the Eocky
Mountains, Greenland, and other parts of the Arctic
regions. In the older Eocene period similar formations
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
Alabama, 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 estuaries where these huge animals were stranded.
Going back to the Cretaceous formation we have the same
indications of persisting 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 cretaceous plant-beds occur in
the site of our continent, even at their deepest part. Upon their bottom
there feathered a vast mass of calcareous mud, com])Osed in great part of
foraminifera, corals, echinoderms, and molluscs. Our English chalk, which
ranges across the north of France, Belgium, Denmark, and the north of
Germany, represents a portion of the deposits of that sea-floor." The
weighty authority of the Director-General of the Geological Survey may
perhaps cause some geologists to modify their views as to the deep-sea
origin of chalk, wlio would liave treated any arguments advanced by myself
as not wortliy of consideration.
H
98 ISLATs^D LIFE
New Jersey, Alabama, Kansas, the sources of the Missouri,
the Rocky Mountains from New Mexico to the Arctic
Ocean, Alaska, California, and in Greenland and Spitz-
bergen; while birds and land reptiles are found in the
Cretaceous deposits of Colorado and other districts near the
centre of the Continent. Fresh-water deposits of this age
are also found on the coast of Brazil. In the lower part of
this formation we have the fresh-water Wealden deposits
of Eno^land, extending^ into France, Hanover, and West-
phalia. In the older Oolite or Jurassic formation we have
abundant proofs of continental conditions in the fresh-water
and " dirt "-beds of the Purbecks in the south of England,
with plants, insects and mammals ; the Bavarian litho-
graphic stone, with fossil birds and insects ; the earlier
" forest marble " of Wiltshire, with ripple-marks, wood, and
broken shells, indicative of an extensive beach ; the Stones-
field slate, with plants, insects, and marsupials ; and the
Oolitic coal of Yorkshire and Sutherlandshire. Beds of the
same age occur in the Rocky Mountains of North America,
containing abundance of Dinosaurians and other reptiles,
among which is the Atlantosaurus, the largest land-animal
yet known to have existed on the earth. Professor O. C.
Marsh de-scribes it as having been between fifty and sixty
feet long, and when standing erect at least thirty feet
high ! ^ Such monsters could hardly have been developed
except in an extensive land area. A small mammal,
Dryulestes, has been discovered in the same deposits. A
rich Jurassic flora has also been found in East Siberia and
the Amur valley. The older Triassic deposits are very
extensively developed in America, and both in the Con-
necticut valley and the Rocky Mountains show tracks or
remains of land reptiles, ami^hibians and mammalia, while
coalfields of the same age in Virginia and Carolina produce
abundance of plants. Here too are found the ancient
mammal, Microlestes; of Wurtemberg, with the ferns,
conifers, and Labyrinthodonts of the Bunter Sandstone in
Germany ; while the beds of rock-salt in this formation,
- Introduction and Succsssion of Vertebrate Life in America, by Professor
0. C. Marsh. Reprinted from the Popular Science Monthly, March, April,
1878.
PHAr. VI GEOGRAPHICAL AND GEOLOGICAL CHANGES 00
both in England and in many parts of the Continent, could
only have been formed in inland seas or lakes, and thus
equally demonstrate continental conditions.
We now pass into the oldest or Pala?ozoic formations,
but find no diminution in the proofs of continental condi-
tions. The Permian formation has a rich flora often pro-
ducing coal in England, France, Saxony, Thuringia, Silesia,
and Eastern Rassia. Coalfields of the same age occur in
Ohio in North America. In the still more ancient Carbon-
iferous formation we find the most remarkable proofs of the
existence of our present land massses at that remote epoch,
in the wonderful extension of coal beds in all the known
continents. We find them in Ireland, England, and
Scotland ; in France, Spain, Belgium, Saxony, Prussia,
Bohemia, Hungary, Sweden, Sj^itzbergen, Siberia, Russia,
Greece, Turkey, and Persia ; in many parts of continental
India, extensively in China, and in Australia, Tasmania,
and New Zealand. In North America there are immense
coal fields, in Nova Scotia and New Brunswick, from Penn-
sylvania southward to Alabama, in Indiana and Illinois,
in Missouri, and even so far west as Colorado ; and there
is also a true coal formation in South Brazil. This wonder-
fully wide distribution of coal, implying, as it does, a rieli
vegetation and extensive land areas, carries back 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 been developed. But we can go even further
back than this, to the preceding Devonian formation, whicli
was almost certainly an inland deposit often containing
remains of fresh-water shells, plants, and even insects ;
while Professor Ramsay believes that he has 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 consider-
ation the fresh-water deposits that still remain to be
discovered, and those extensive areas where they have
been destroyed by denudation or remain deej^ly covered uj)
by later marine or volcanic formations, we cannot but be
struck by the abounding proofs of the permanence of the
' Physical G'eograi)hy and Geology of Great liritain, '.lli K<1. ]>. (51.
II '1
100 ISLAND LIFE
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 Peoinanence of Con-
tinents and Oceans. — Coming to the question from the other
side, Mr. Darwin has adduced an argument of considerable
weight in favour of the permanence of the great oceans.
He says {Origin of Si)ecics, 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 exception of New Zealand,
if this can be called a truly oceanic island) is as yet known
to afford even a fragment of any Palaeozoic or Secondary
formation. Hence we may perhaps infer that during the
Palieozoic and Secondary periods neither continents nor
continental islands existed where our oceans now extend ;
for had they existed, Palaeozoic and Secondary formations
would in all probability have been accumulated from sedi-
ment 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 Ave may infer anything from these
facts, Ave may infer that, Avhere our oceans now extend,
oceans have extended from the remotest period of Avhich
Ave have any record ; and, on the other hand, that Avhere
continents now exist, large tracts of land haA^e existed,
subjected no doubt to great oscillations of level, since the
Cambrian period." This argument standing by itself has
not received the attention it deserves, but coming in sup-
port of the long series of facts of an altogether distinct
nature, going to shoAV the permanence of continents, the
cumulative effect of the Avhole must, I think, be admitted
to be irresistible.^
1 Of late it has been the custom to quote the so-called '•'ridge" down
the centre of the Atlantic as indicating an extensive ancient land. Even
Professor Judd at one time adoj.ted this view, spejiking of the great belt of
CHAP. VI GEOGRAPHICAL AND GEOLOGICAL ("IIAXGES 101
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 our continental areas also goes to prove
that they have been subjected to wonderful and repeated
changes in detail. Every square mile of their surface has
been again and again under water, sometimes a few hundred
feet deep, sometimes perhaps several thousands. Lakes
and inland seas have been formed, have been filled up with
sediment, and been subsequently raised into hills or even
mountains. Arms of the sea have existed crossing the
continents in various directions, and thus completely
isolating the divided portions for varying intervals. Seas
have been changed into deserts and deserts into seas.
Volcanoes have grown into mountains, have been degraded
and sunk beneath the ocean, have been covered with
sedimentary deposits, and again raised up into mountain
ranges ; while other mountains have been formed by the
Tertiary volcanoes " which extended through Greenland, Iceland, the Faroe
Islands, the Hebrides, Ireland, Central France, the Iberian Peninsula, the
Azores, Madeira, Canaries, Cape de Verde Islands, Ascension, St. Helena,
and Tristan d'Acunha, and which constituted as shown liy the recent
soundings of H.i\I.S. Challenger a mountain-range, comparable in its
extent, elevation, and volcanic character with the Andes of South America"
[Geological Mag. 1874, ^. 71). On examining the diagram of the Atlantic
Ocean in the Challenger Rcjyorts, No, 7, a considerable part of this ridge is
foimdto be more than 1,900 fathoms deep, while the portion called the
"Connecting Ridge " seems to be due in part to the deposits carried out by
the River Amazon. In the neighbourhood of the Azores, St. Paul's Rocks,
Ascension, and Tristan d'Acunha arc considerable areas varying from 1,200
to 1,500 fathoms deep, Avliile the rest of the ridge is usually 1,800 or 1,900
fathoms. The shallower water is no doubt due to volcanic upheaval and
the accumulation of volcanic ejections, and there may be many other
deeply submerged old volcanoes on the ridge ; but that it ever formed a
chain of mountains "comparable in elevation with the Andes," there
seems not a particle of evidence to prove. It is however probable that
this ridge indicates the former existence of some considerable Atlantic
islands, which may serve to exjdain the presence of a few identical genera,
and even species of plants and insects in Africa and Soutli America, while
the main body of the fauna and flora of these two continents remains
radically distinct.
In my Darwinism (pp. 344-5) I have given an additional argument
founded on the comparative height and area of land with the depth and
area of ocean, which seems to me to add considcral>ly to tlie weight of tin-
evidence here submitted for the permanence of oceanic and continental
areas.
102 ISLAND LIFE
upraised coral reefs of inland seas. The mountains of one
period have disappeared by denudation or subsidence,
while the mountains of the succeedicg 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 Ani-
mals.— 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 hemisphere to the other. Owing to the
remarkable continuity of all the land masses, animals and
plants must have often been compelled 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 Avide-spread groups
whose distribution often j^uzzles us. Owing to the repeated
isolation of portions of continents for long periods, special
forms of life Avould 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 increasing complexity, and thus lead to the develop-
ment and preservation 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 j^roved by the Extinct Animals of
Different Epochs. — We thus find that, while the inorganic
world has been m a state of continual though very gradual
change, the species of the organic world have also been
slowly changing in form 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 pre-
served in the rocks. Everywhere the animals which have
most recently become extinct resemble more or less closely
those which now live in the same country ; and where
CHAP. VI GEOGRAPHICAL AND GEOLOGICAL CHANGES fo3
there are exceptions to the rule, we can generally trace
them to some changed conditions which have led to the
extinction of certain types. But when we go a little
further back, to the late or middle Tertiary deposits, we
almost always find, along with forms which might have
been the ancestors of some now living, others which are
only now found in remote regions and often in distinct
continents — clear indications of those extensive migrations
which have ever been going on. Every large island
contains in its animal inhabitants a record of the period
when it was last separated from the adjacent continent,
while some portions of existing continents still show by the
comparative poverty and speciality of their animals' that
at no distant epoch they were cut off by arms of the sea
and formed islands. If the geological record were more
perfect, or even if we had as good a knowledge of that record
in all parts of the w^orld as Ave have in Europe and North
America, we could arrive at much more accurate 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 inhabitants,
and can sketch out with confidence many of the changes
they must have undergone.
Sttmmary of Evidence for the G aural Permanence of
Continents and Oceans. — As this question of the permanence
of our continents or, rather, of the continental areas, lies at
the root of all our inquiries into the past changes 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 summarise the various kinds of
evidence which go to establish it.^ We know as a fact
^ In a review of Mr. T. jMellard Reade's Chemical Denudation and
Geological Time, in Nature (Oct. 2nd, 1879), the writer remarks as follows :—
" One of the funny notions of some scientific thinkers meets with no fixvour
from ]\Ir. Reade, whose geological knowledge is practical as well as theoretical.
They consider that because the older rocks contain nothing like the present
red clays, &c., of the ocean floor, that the oceans have always been in their
present positions. Air. Readc points out that the first proposition is not
yet proved, and the distribution of animals and plants and the fixct that
the bulk of the strata on land are of marine origin are opposed to tlie hypo-
104 ISLAND LIFE
that all sedimentary 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 150 or 200 miles wide were rarely, if ever,
formed at the same time. The further we go from the
land the less rapidly deposition takes place, hence the
great bulk of all the strata must have been formed near
land. Some deposits are, it is true, continually forming in
the midst of the great oceans, but these are chiefly organic
and increase very slowly, and there is no j)roof that any
part of the series of known geological formations exactly
resembles them. Chalk, which is still believed to be such a
deposit by many naturalists, has been shown, by its con-
tained fossils, to be a comparatively shallow water forma-
tion— 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 deposits, showing that every
part of the existing land has in turn been on the sea-shore ;
and we also find in all periods lacustrine formations 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 lacustrine deposits can be traced back through
every period, from the newer Tertiary to the Devonian and
Cambrian, and in every continent which has been geo-
logically explored ; and thus complete the proof that our
continents have been in existence under ever changing
thesis." We must leave it to our readers to decide whether the ''notion "
developed in this chapter is "funny," or Avhether such hasty and superficial
arguments as those here quoted from a "practical geologist" have any
value as against the different 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 Sir
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 marine 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 comparatively
shallow water."
CHAr. Yi GEOGRAPHICAL AND GEOLOGICAL CHANGES
in:,
forms throughout the whole of that enormous hipse of
time.
On the side of tlie oceans we have also a great wei^^ht
of evidence in favour 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 anything found upon tlie land-
surface, we have the extraordinary fact that the countless
islands scattered over their whole area (with one or two
exceptions only and those comparatively near to continental
areas) never contain any Palaeozoic or Secondary rocks
that is, have not jDreserved any fragments of the supposed
ancient continents, nor of the deposits which must have
resulted from their denudation during the whole period of
their existence ! The supposed exceptions are New
Zealand and the Seychelles Islands, both situated near
to continents and not really oceanic, 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.
CHAPTER YII
CHANGES OF CLIMATE WHICH HAVE INFLUENCED THE
DISPERSAL OF ORGANISMS : THE GLACIAL EPOCH
Proofs of the Recent Occurrence of a Glacial Epoch — j\Ioraines — Travelled
Blocks — Glacial Deposits of Scotland : the " Till " — Inferences from the
Glacial Phenomena of Scotland — Glacial Phenomena of North America
— Effects of the Glacial Epoch on Animal Life — Warm and Cold Periods
— Palreontological Evidence of Alternate Cold and AVarm Periods-
Evidence of Interglacial Warm Periods on the Continent and in North
America — Migrations and Extinctions of Organisms caused by the
Glacial Epoch.
We have now to consider another set of physical revohi-
tions which have profoundly affected the whole organic
world. Besides 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 has 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
I
CHAP, vir THE GLACIAL EPOCH 107
other. The evidence for both these changes having oc-
curred is conclusive ; and as they must be taken account of
whenever we endeavour to explain the past migrations and
actual distribution of the animal world, a brief outline of
the more important facts and of the conclusions they lead
to must be here given.
Proofs of the Recent Oceurrence of a Glacial Epoch. — The
phenomena that prove the recent occurrence of glacial
epochs in the temperate regions are exceedingly varied,
and extend over very wide areas. It will be well therefore
to state, first, what those facts are as exhibited in our own
country, referring afterwards to similar phenomena in
other parts of the world.
Perhaps the most striking of all the evidences of giacia-
tion are the grooved, scratched, or striated rocks. These
occur abundantly in Scotland, Cumberland, and North
Wales, and no rational explanation of them has ever been
given except that they were formed by glaciers. In many
valleys, as, for instance, that of Llanberris in North Wales,
hundreds of examples may be seen, consisting of deep
grooves several inches wide, smaller furrows, and stride of
extreme fineness wherever the rock is of sufficiently close
and hard texture to receive such marks. These grooves
or scratches are often many yards long, they are found in
the bed of the valley as well as high up on its sides, and
they are almost all without exception in one general direc-
tion— that of the valley itself, even though the particular
surface they are upon slopes in another direction. When
the native covering of turf is cleared away from the rock
the grooves and striae are often found in great perfection, and
there is reason to believe that such markings cover, or have
once covered, a large part of the surface. Accompanying
these markings we find another, hardly less curious phe-
nomenon, the rounding off or planing down of the hardest
rocks to a smooth undulating surface. Hard crystalline
schists with their strata nearly vertical, and which one
would expect to find exposing jagged edges, arc found
ground off to a perfectly smooth but never to a fiat surface.
These rounded surfaces are found not only on single rocks
but over whole valleys and mountain sides, and form wliat
103 ISLAND LIFE
are termed roches moutonnecs, from their often having the
appearance at a distance of sheep lying down.
Now these two phenomena are actually produced hy
existing glaciers, while there is no other known or even
conceivable cause that could have produced them. When-
ever the Swiss glaciers retreat 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 phe-
nomena are so exactly identical that no one who has ever
compared them can doubt that they are due to the same
causes. But we have further and even more convincing-
evidence. Glaciers produce many other effects besides
these two, and whatever effects they produce in Switzer-
land, in Norway, or in Greenland, we find examples of
similar effects having been produced in our own country.
The most striking of these are moraines and travelled
blocks.
Moraines.- — Almost every existing glacier carries down
with it great masses of rock, stones, and earth, which fall
on its surface from the precipices and mountain slopes
which hem it in, or the rocky peaks which rise above it.
As the glacier slowly moves downward, this debris forms
long lines on each side, or on the centre whenever two
glacier-streams unite, and is deposited at its termination
in a huge mound called the terminal moraine. The de-
crease of a glacier may often be traced by successive old
moraines across the valley up which it has retreated.
When once seen and examined, these moraines can always
be distinguished almost at a glance. Their position is
most remarkable, having no apparent natural relation to
tlie form of the valley or the surrounding slopes, so that
they look like huge earthworks formed by man for pur-
poses of defence. Their composition is equally peculiar,
consisting of a mixture of earth and rocks of all sizes,
usually without any arrangement, the rocks often being
huge angular masses just as they had fallen from the sur-
rounding precipices. Some of these rock masses often rest
on the very top of the moraine in positions where no other
natural force but that of ice could have placed them.
(HAP. Vll
THE GLACIAL EPOCH
109
Exactly similar mounds are found in the valleys of North
Wales and Scotland, and always wliere tlie otlier eviduncos
of ice-action occur abundantly.
Travelled Blocks. — The phenomenon of travelled or
perched blocks is also a common one in all glacier
A GLACIER WITH MORAINES,
countries, marking out very clearly the former extent of
the ice. When a glacier fills a lateral valley, its foot will
sometimes cross over the main valley and abut against its
opposite slope, and it will deposit there some portion of its
terminal moraine. But in these circumstances the end of
the glacier not being confined laterally will spread out.
110 ISLAND LIFE
and the moraine matter will be distributed over a large
surface, so that the only well-marked token of its presence
will be the larger masses of rock that may have been
brought down. Such blocks are found abundantly in
many of the districts of our own country where other
marks of glaciation exist, and they often rest on ridges or
hillocks over which the ice has passed, these elevations
consisting sometimes of loose material and sometimes of
rock different from that of ivhich the Uocks are composed.
These are called travelled blocks, and can almost always be
traced to their source in one of the higher valleys from
which the glacier descended. Some of the most remarkable
examples of such travelled blocks are to be found on the
southern slopes of the Jura, These consist of enormous
angular blocks of granite, gneiss, and other crystalline
rocks, quite foreign to the Jura mountains, but exactly
agreeing with those of the Alpine range fifty miles away
across the great central valley of Switzerland. One of
the largest of these blocks is forty feet diameter, and is
situated 900 feet above the level of the Lake of Neufchatel.
These blocks have been proved by Swiss geologists to have
been brought by the ancient glacier of the Rhone which
was fed by the whole Alpine range from Mont Blanc to
the Furka Pass. This glacier must have been many
thousand feet thick at the mouth of the Rhone valley near
the head of the Lake of Geneva, since it spread over the
whole of the great valley of Switzerland, extending from
Geneva to Neufchatel, Berne, and Soleure, and even on the
flanks of the Jura, reached a maximum height of 2,015
feet above the valley. The numerous blocks scattered
over the Jura for a distance of about a hundred miles vary
considerably in the material of which they are composed,
but they are found to be each traceable to a part of the
Alps corresponding to their position, on the theory that
they have been brought by a glacier spreading out from
the Rhone valley. Thus, all the blocks situated to the
east of a central point G (see map) can be traced to the
eastern side of the Rhone valley (l e d), while those found
towards Geneva have all come from the west side {p h).
It is also very suggestive that the highest blocks on the
I
CHAP. YII
THE GLACIAL EPOCH
Jura at G have come from the eastern slioulder of ]M«)nt
Blanc in the direct line A B F G. Here tlie glacier \vo\il(l
naturally preserve its greatest thickness, wliile as it sjiread
out eastward and westward it would become tliinner. We
accordingly find that the travelled blocks on either side of
MonL Blanc
MAP SHOWING THE roiRSE OF THE ANCIENT GLACIER OF THE RHONE AND THK
DISTRIBUTION OF ERRATIC BLOCKS ON THE JURA.
the central point become lower and lower, till near Soleure
and Geneva they are not more than 500 feet above the
valley. The evidence is altogether so conclusive that, after
personal examination of the district in company with
eminent Swiss geologists, Sir Charles Lyell gavi» up tlie
112 ISLAND LIFE tart i
view he had first adopted — that the blocks had been
carried by floating ice during a period of submergence — as
altogether untenable.^
The phenomena now described demonstrate a change of
climate sufiicient to cover all our higher mountains with
perpetual snow, and fill the adjacent valleys with huge
glaciers at least as extensive as those now found in Switzer-
land. But there are other phenomena, best developed in
the northern part of our islands, which show that even
this state of things was but the concluding phase of the
glacial period, which, during its maximum development,
must 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 geolo-
gists are acquainted with the weight of evidence for this
statement, and as it is most important for our purpose to
understand the amount of the climatal changes the northern
hemisphere has imdergone, I will endeavour to make the
evidence intelligible, referring my readers for full details
to Dr. James Geikie's descriptions and illustrations.^
Glacial Dej^osits of Scotland : the " Till" — 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 sub-
mergence. But below them all, and often resting directly
on the rock-surface, there are extensive layers of a very
tough olayey deposit known as " till." The till is very fine
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 striae often crossing each other in various
directions. 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
1 Antiquity of Man, 4tli Ed. pp. 340-348.
- The Great Ice Age and its Relation to the Antiquity of Man. By James
Geikie, F.R.S. (Isbister and Co.. 1874.)
CHAP, vri THE GLACIAL EPOCH H3
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 hundred 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 hi<'h
as two thousand feet above the sea, in hollows or hill-sides
where it seems to have been 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 colour and texture, and the nature of
the stones it contains, all correspond to the cliaracter 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 referred to),
so that it is certainly an earlier deposit.
Throughout Scotland, where "till" is found, the glacial
striae, perched blocks, roclics moutonn^cs, and other marks
of glacial action, occur very high up the mountains to at
least 3,000 and often even to 3,500 feet above the sea,
while all lower hills and mountains are rounded and
grooved on their very summits ; and these grooves always
radiate outwards from the highest peaks and ridges towards
the valleys or the sea.
Inferences from the Glacial Phenomena of Scotland. — Now
all these phenomena taken together render it certain that
the whole of Scotland was once buried in a vast sea of ice,
out of which only the highest mountains raised their
summits. There is absolutely no escape from this con-
clusion ; for the facts which lead to it are not local — found
only in one spot or one valley — but general throughout
the entire lengrth and breadth of Scotland ; and are besides
supported by such a mass of detailed corroborative evidence
as to amount to absolute demonstration. The weight of
this vast ice-sheet, at least three thousand feet in maxi-
mum thickness, and continually moving seaward with a
slow grinding motion like that of all existing glaciers,
114 ISLAND LIFE
must have ground down the whole surface of the country,
especially all the prominences, leaving the rounded rocks
as well as the grooves and strise we still see marking the
direction of its motion. All the loose stones and rock-
masses which lay on the surface would be pressed into the
ice ; the harder blocks would serve as scratching and grind-
ing tools, and would thus themselves become rounded,
scratched, and striated, as we see them, while all the softer
masses would be ground up into impalpable mud along
with the material planed off the rocky projections of
the country, leaving them in the condition of roclics
moiitonn^cs.
The peculiar characters of the " till," its fineness and
tenacity, correspond closely with the fine matter which
now issues from under all glaciers, making the streams
milky white, yellow, or brown, according to the nature of
the rock. The sediment from such w^ater is a fine unctuous,
sticky deposit, only needing pressure to form it into a
tenacious clay ; and when " till " is exposed to the action
of water, it dissolves into a similar soft, sticky, unctuous
mud. The present glaciers of the Alps, being confined to
valleys which carry off a large 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
little drainage water, and thus the mud and stones collected
in vast compact masses in all the hollows, and especially
in the lower flat valleys, so that, when the ice retreated,
the whole country was more or less covered with it. It
was then, no doubt, rapidly denuded by rain and rivers,
but, as we have seen, great quantities remain to the
present day to tell the tale of its wonderful formation.^
1 This view of the formation of "till" is that adopted by Dr. Geikie,
and upheld by almost all the Scotch, Swiss, and Scandinavian geologists.
The objection however is made by many eminent English geologists, includ-
ing the late ]\Ir. Searles V. AVood, Jun., that mud ground off the rocks
cannot remain beneath the ice, forming sheets of great thickness, because
the glacier cannot at the same time grind down solid rock and yet
pass over the surface of soft mud and loose stones. But this difficulty
will disappear 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 together, and
at last produced an ice-sheet covering the whole country. The grind
CHAP, vir THE GLACIAL EPOCH 115
There is good evidence that, when the ice was at its maxi-
mum, it extended not only over the land, but far out to
sea, covering all the Scottish islands, and stretching in one
connected sheet to Ireland and Wales, where all the
evidences of glaciation are as well marked as in Scotland,
though the ice did not of course attain quite so great a
thickness.^
ing power is the motion and pressure of the ice, and tlie pressure will
depend on its thickness. Now the points of niaxiinum tliickness must
have often changed their positions, and the result would bo 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 accumulate at this part simply because there was no escape for
it. Whenever the jiressure 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. During this process the superfluous water
would no doubt escape through fissures or pores of the ice, and would
leave the mud and stones in that excessively compressed and tenacious
condition in which the "till" 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 narrowed 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 "till " 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 beneath 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 was little or no drainage water compared to the
enormous area covered with ice, the great bulk of the debris must have
gathered 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 foi-
any large part of it to be disposed of in this way.
^ That the ice-sheet was continuous from Scotland to Ireland is proved
by the glacial phenomena in the Isle of ]\Ian, where "till " similar to that
in Scotland abounds, and rocks are found in it which must have lome frdiu
Cumberland and Scotland, as well as from the north of Ireland. This
would show that glaciers from each of these districts reacheil tlie Isle of
]\Ian, where they met and flowed southwards down the Irish Sea. Ice-
marks are traced over the tops of the mountains which are nearly 2,000 feet
high. (Sec A Sketch of the Gcolorjy of the Isle of Man, bv John Home,
F.G.S. Trans, of the Edin. Geol. Sac. Vol. II. pt. 3, 1874.)
1 '2
116 ISLAND LIFE
It is evident that the change of climate requisite to
produce such marvellous effects in the British Isles could
not have been local, and we accordingly find strikingly
similar proofs that Scandinavia and all northern Europe
have also been covered with a huge ice-sheet ; while we
have already seen that a similar gigantic glacier buried the
Alps, carrying granitic blocks to the Jura, where it de-
posited them at a height of 3,450 feet above the sea;
while to the south, in the plains of Italy, the terminal
moraines left by the retreating glaciers have formed exten-
sive hills, those of Ivrea the work of the great glacier from
the Val d'Aosta being fifteen miles across and from 700 to
1,500 feet high.
Glacial Phenomena in North America. — In North
America the marks of glaciation are even more extensive
and striking than in Europe, stretching over the whole of
Canada and to the south of the great lakes as far as
latitude 39°. There is, in all these countries, a wide-spread
deposit like the " till" of Scotland, produced by the grind-
ing of the great ice-sheet when it was at its maximum
thickness ; and also extensive beds of moraine-matter, true
moraines, and travelled blocks, left by the glaciers as they
retreated towards the mountains and finally withdrew into
the upland valleys. There are, also, in Britain, Scandin-
avia, and North America, proofs of the submersion of the
land beneath the sea to a depth of upwards of a thousand
feet ; but this is a subject we need not here enter upon, as
our special object is to show the reality and amount of that
wonderful and comparatively recent change of climate
termed the glacial epoch.
Many persons, even among scientific men, who have not
given 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 simj^le 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
THE GLACIAL ErOC'II n;
of the evidence on which the existence of the glacial epocli
depends. There is perhaps no great conclusion in any
science which rests upon a surer foundation than this ; and
if Ave are to be guided by our reason at all in deducing tlie
unknown from the known, the past from the present, wo
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 Ei)ocli on Animal Life : Warm and
Cold Periods. — It is hardly necessary to point out what an
important effect this great climatal cycle must have liad
upon all living things. When an icy mantle crept gradu-
ally 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 exter-
mination of many forms, and the migration of others into new
areas. But these effects must have been greatly multiplied
and intensified if, as there is very good reason to believe,
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 intercalated
beds are very thin, but in other cases they are twenty or
thirty feet thick, and in them have been found remains of
the extinct ox, the Irish elk, the horse, reindeer and
mammoth. Here we have evidence of two distinct periods
of intense cold, and an intervening milder jjeriod sufh-
ciently prolonged for the country to become covered with
vegetation and stocked with animal life. In some districts
borings have proved the existence of no less than four
118 ISLAND LIFE part i
distinct formations of " till " separated from each other by
beds of sand from two to twenty feet in thickness.^ Facts
of a similar nature have been observed in other parts of our
islands. In the east of England, Mr. Skertchly (of the
Geological Survey) enumerates four distinct boulder clays
with intervening deposits of gravels and sands.^ Mr.
Searles V. Wood, Jun,, classes the most recent (Hessle)
boulder clay as " post-glacial," but he admits an inter-
vening warmer period, characterised by southern forms of
mollusca and insects, after which glacial conditions again
prevailed with northern types of mollusca.^ Elsewhere he
says : " Looking at the presence of such fluviatile mollusca
as Cyrena flitminalis and Unio littoralis and of such
mammalia as the hippopotamus and other great pach}^-
derms, and of such a littoral Lusitanian 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 me that the climate of the earlier part of the
post-glacial period in England was possibly even warmer
than our present climate ; and that it was succeeded by a
refrigeration sufficiently severe to cause ice to form all
round our coasts, and glaciers to accumulate in the valleys
of the mountain districts ; and that this increased severity
of climate was preceded, and partially accompanied, by a
limited submergence, which nowhere apparently exceeded
300 feet, and reached that amount only in the northern
counties of England." ■* This decided admission of an
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 accompanying
depo^ession of the land, accompanying the increased cold,
because many geologists maintain that a greater elevation
of the land is the true and sufficient explanation of glacial
periods.
^ The Great Ice Age, p. 177.
~ These are named, in descending order, Hessle Boulder Clay, Purple
Boulder Clay, Chalky Boulder Clay, and Lower Boulder Clay — below which
is the Norwich Crag.
^ "On the Climate of the Post-Glacial Period." Geological Magazine,
1872, pp. 158, 160.
■* Geological Magazine, 1S7C, p. 396.
THE GLACIAL EPOCH 119
Further evidence of this alternation is found both in the
Isle of Man and in Ireland, where two distinct boulder
clays have been described with intervening beds of gravels
and sands.
Palcvontological Evidence of Alternate Cold and Wann
Periods. — Especially suggestive of a period warmer than
the present, immediately following glacial conditions, is
the occurrence of the hippopotamus in caves, brick-earths,
and gravels of palaeolithic age. Entire skeletons of this
animal have been found at Leeds in a bed of dark blue
clay overlaid by gravel. Further north at Kirkdale cave,
in N. Lat. 54° 15', remains of the hippopotamus occur abun-
dantly along with those of the Elcplias antiquus, Eltino-
ceros hemitceclnis, reindeer, bear, horse, and other quadru-
peds, and with countless remains of the hyaenas which
devoured them ; wliile it has also been found in cave de-
posits in Glamorganshire, at Durdham Down near Bristol,
and in the i3ost-Pliocene drifts of England and France.
The fact of the hippopotamus having lived at 54° N. Lat.
in England immediately after the glacial period seems
quite inconsistent with a mere gradual amelioration of
climate from that time till the present day. The entirely
tropical distribution of the existing animal and the large
(piantity of vegetable food which it requires both indicate
a much warmer climate than now prevails in any part of
Europe. The problem, however, is complicated by the fact
that, both in the cave-deposits and river gravels, its remains
are often found associated with those of animals that
imply a cold climate, such as the reindeer, the mammoth,
or the woolly rhinoceros. At this time the British Isles
were joined to the Continent, and a great river formed by
the union of the Rhine, the Elbe and all the eastern rivers
of England, flowed northward through what is now the
German Ocean. The hippopotamus appears to have been
abundant in Central Europe before the glacial epoch, but
during the height of the cold was probably driven to the
south of France, whence it may have returned by way of
the Rhone valley, some of the tributaries of that river
approaching those of the Rhine within a mile or two a
little south-west of Mulhausen, whence it would easily
120 ISLAND LIFE
reach Yorkshire. Professor Boyd Dawkins supposes that
at this time our summers were warm, as in Middle Asia
and the United States, while the winters were cold, and
that the southern and northern animals migrated to and
fro over the great plains which extended from Britain to
the Continent. The following extract indicates how such
a migration was calculated to bring about the peculiar
association of sub-tropical and arctic forms.
"It must not, however, be supposed that the southern
animals migrated from the Mediterranean area as far
north as Yorkshire in the same year, or the northern as
far south as the Mediterranean. There were, as we shall
see presently, secular changes of climate in Pleistocene
Europe, and while the cold was at its maximum the
arctic animals arrived at the southern limit, and while
it was at its minimum the spotted hyoena and hippo-
potamus and other southern animuls roamed to their
northern limit. Thus every part of the middle zone has
been successively the frontier between the northern and
southern groups, and consequently their remains are
mingled together in the caverns and river-deposits, under
conditions which prove them to have been contemporaries
in the same region. In some of the caverns, such as that
of Kirkdale, the hyaena preyed upon the reindeer at one
time of the year and the hippopotamus at another. In
this manner the association of northern and southern
animals may be explained by their migration according to
the seasons ; and their association over so wide an area as
the middle zone, by the secular changes of climate by
which each part of the zone in turn was traversed by the
advancino^ and retreating' animals." ^
When we consider that remains of the hippopotamus
have been found in the caves of North Wales and Bristol
as well as in those of Yorkshire, associated in all with
the reindeer and in some with the woolly rhinoceros or
the mammoth, and that the animal must have reached
these localities by means of slow-flowing rivers or flooded
marshes by very circuitous routes, we shall be convinced
that these long journeys from the warmer regions of South
^ Early Man in Britain and his Place in the T'ertiary Period, p, 113.
THE GLACIAL EPOCH ]j]
Europe could not have been made during the short sum-
mers of the glacial period. Thus the very existence of
such an animal in such remote localities closely associated
with those implying almost an arctic winter climate ap-
pears to afford a strong support to the argument for tlio
existence of warm inter-glacial or post-glacial periods.
Emdcncc of Inter glacial Warm Pcrioch 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 recognised, between which was a warm period
when veo'etation was so luxuriant as to form beds of lio-
nite sufficiently thick to be worked for coal. The plants
found in these deposits are similar to those now inhabiting
Switzerland — pines, oaks, birches, larch, etc., but numer-
ous animal remains are also found, showing that the
country was then inhabited by an elephant [Elcphas
antigitus), a rhinoceros {Rhinoceros megarhinus), the urus
{Bos p7'i7uigenius), the red deer (Cervics ele^jhas), and tlie
cave-bear, ( JJrsus sjjeloiics) ; and there were 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 uj^per 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 remains and
fresh-water organisms. These deposits are seen to extend
continuously for more than nine miles, and the fossiliferous
interglacial 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 48 feet
of sand and loam, and thirdly of unstratitied " till " full
of striated stones — six feet thick.^ On the other side of
the continent, in British Columbia, Mr. G. M. Dawson,
geologist to the North American Boundary Connnission,
^ Kcer' s Prwi(£val World of Switzerland Vol. IL, pp. 148-168.
^ Dr. James Geikie in Geological Magazine, 1878, ]>. 77.
122 ISLAND LIFE tart i
has discovered similar evidence of two glaciations divided
from each other by a warm period.
This remarkable series of observations, spread over
so wide an area, seems to afford ample j)roof that the
glacial epoch did not consist merely of one process of
change, from a temperate to a cold and arctic climate,
which having reached a maximum, 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 possibly expect to find more than the most
slender indications of them, because each succeeding ice-
sheet would necessarily grind down or otherwise destroy
much of the superficial deposits left by its predecessors,
while the torrents that must always have accompanied the
melting of these huge masses of ice Avould wash away
even such fragments as might have escaped the ice itself.
It is a fortunate thing therefore, that we should find any
fragments of these interglacial deposits containing animal
and vegetable 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 earlier. Of
such deposits as were formed on land during the coming
on of the glacial epoch when it was continually increasing
in severity hardly a trace has been preserved, because each
succeeding extension of the ice being greater and thicker
than the last, destroyed what had gone before it till the
maximum was reached.
Migrations and Extinction of Organisms caused hy the
Glacial Ujjoch. — Our last glacial epoch was accompanied
by at least two considerable submergences and elevations
of the land, and there is some reason to think, as we have
already explained, that the two classes of phenomena are
connected as cause and effect. We can easily see how such
repeated submergences and elevations would increase and
aggravate the migrations and extinctions that a glacial
epoch is calculated to produce. We can therefore hardly
fail to be ridit in attributino- the Avonderful chano^es in
THE GLACIAL K1'0( 1[ 120
uiiimal and vegetable life that have occurred in Europe
and N. America between the Miocene Period and tlic
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 wliole host of tlje liiglier
animal forms, and secondly, in a complete change of types
due to extinction and mis^ration, leadino^ to a much oreater
difference between the vegetable and animal forms of the
eastern and western hemisphere than before existed.
Many large and powerful rnamn^alia 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 ex-
tinct while others continued to exist in more southern
lands. Among the first class are the sabre-toothed tiger,
the extinct Siberian camel (Merycotherium), three species
of elephant, two of rhinoceros, two bears, five species of
deer, and the gigantic beaver ; among the latter are the
liyaina, bear, and lion, which are considered to be only
varieties of those Avhich once inhabited Britain. Down to
PUocene times the flora of Europe was very similar to that
which now prevails in Eastern Asia and Eastern North
America. The late Professor Asa Gray has jDointed out
that hundreds of species of trees and shrubs of pecuUar
genera which still flourish in those countries are now com-
pletely wanting in EurojDe, and there is good reason to
believe that these were exterminated during the glacial
period, being cut off from a southern migration, first by
the Alps, and then by the Mediterranean ; Avhereas in
eastern America and Asia the mountain chains run in a
north and south direction, and there is nothing to prevent
the flora from having been preserved by a southward
misration into a milder resfion.^
■'&'
Our next two chapters will be devoted to a discussion
of the causes which brought about tlie glacial epocli, and
that still more extraordinary climatic j^jhenomenon — the
^ This subject is admirably discussed in Professor Asa Gray's Lecture on
" Forest Geoffrajdiy and Archaeology" in the American Journal of ticicnc:
and Arts, Vol. XVL 1878.
124 ISLAND LIFE
mild climate and luxuriant vegetation of the Arctic zone.
If my readers Avill follow me with the care and attention
so difficult and interesting a problem requires and deserves,
they will find that I have grappled with all the more im-
portant facts which have to be accounted for, and have
offered what I believe is the first complete and sufficient
explanation of them. The important influence of climatal
changes on the dispersal of animals and plants is a suffi-
cient justiflcation for introducing such a discussion into
the present volume.
CHAPTER VIII
THE CAUSES OF GLACIAL EPOCHS
A^arious Suggested Causes— Astronomical Causes of Changes of Climate—
Dillerence of Temperature caused by Varying Distance of the Sun-
Properties of Air and AVater, Snow and Ice, 'in Relation to Climates-
Effects of Snow on Climate— Higli Lantl and Great Aloisture Essential to
the Initiation of a Glacial Epoch— Perpetual Snow nowhere Exists on
Lowlands— Conditions Determining the Presence or Absence of Perpetual
Snow— Efficiency of Astronomical Causes in Producing Glaciation—
Action of Meteorological causes in Intensifying Glaciation— Summary
of Causes of Glaciation— Effect of Clouds and Fog in cutting otf the
Sun's Heat— South Temperate America as Illustrating the Inlhience of
Astronomical Causes on Climate— Geograi)hical Clianges how far a
Cause of Glaciation— Land acting as a Barrier to Ocean-currents— Tlie
theory of Interglacial Periods and their Probable Character— Prol)al)le
Effect of Winter in Aphelion on the Climate of Britain— The Essential
Principle of Climatal Change Restated— Probable Date of the last
Glacial Epoch— Changes of the Sea-level dependent on Glaciation— The
Planet ]\Iars as bearing on the Theory of Excentricity as a Cause of
Glacial Epochs.
No less than seven different causes have been at various
times advanced to account for the glacial epoch and otlier
changes of climate which the geological record proves to
have taken place. These, as enumerated by Mr. Searles V.
Wood, Jun., are as follows : —
1. A decrease in the original heat of our |)laiict.
2. Changes in the obliquity of the ecHi)tic.
'3. The combined eftect of the precession of the L'(iuiiioxes
and of the excentricity of the earth's orbit.
4. Changes in the distribution of land and water.
126 ISLAND LIFE
5. Changes in the position of the earth's axis of rota-
tion.
G. A variation in the amount of heat radiated by tlie
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 in-
adequate to produce the observed effects. Causes (5) (6)
and (7) are all purely hypothetical, for though such changes
may have occurred there is no evidence that they have
occurred during geological time ; and it is besides certain
that they would not, either singly or combined, be adequate
to explain the whole of the phenomena. There remain
causes (3) and (4), which have the advantage of being de-
monstrated facts, and which are universally admitted to be
capable of producing some effect of the nature required, the
only question being whether, either alone or in combination,
they are adequate to produce all the observed effects. It
is therefore to these two causes that we shall confine our
inquiry, taking first those astronomical causes whose com-
plex and wide reaching effects have been so admirably ex-
plained and discussed by Dr. Croll in numerous papers and
in his work— " Climate and Time in their Geological
Relations."
:^ Astronomical Causes of Ghanrjes of Climate.— The earth
moves in an elliptical orbit round the sun, which is situated
in one of the foci of the ellipse, so that the distance of the
sun from us varies during the year to a considerable
amount. Strange to say we are now three millions of
miles nearer to the sun in winter than in summer, while
the reverse is the case in the southern hemisphere ; and
this must have some effect in making our northern winters
less severe' than those of the south temperate zone. But
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 hemi-
sphere. 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 as long as our summer is now
t
CHAP. VI ir THE CAUSES OF GLACIAL EPOCHS 127
and we were also three million miles furtlier from the sun
at the former period, a very decided difference of climate
would result — our winter would be colder and longer, our
summer hotter and shorter. Now there is a combination
of astronomical revolutions (the precession of the ecpiinoxes
and the motion of the aphelion) which actually brings this
change about every 10,oI}0~yHaTs, so that after this interval
the condition of the two hemispheres is reversed as regards
nearness to the sun in summer, and comparative 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
N. HEMISPHERE WINTER IN APHELIOK S .HEMISPHERE WINTER IN APHELION
GLACIAL EPOCH IN GLACIAL EPOCH IN
N.HEMISPHERE S. HEMISPHERE
PIAGRAM SHOWING THE ALTERED POSITION OF THE POLES AT INTERVALS OF 10,500 YEARS
PRODUCED BY THE PRECESSION OF THE EQUINOXES AND THE MOTION OF THE APHELION ;
AND ITS EFFECT ON CLIMATE DURING A PERIOD OF HIGH EXCENTRICITV.
seen in the great extension of the antarctic ice-fields, and
the existence of glaciers at the sea-level in the southern
hemisphere, in latitudes corresponding to that of England ;
but it is not supposed that similar etfects were produced
with us at the last cold period, 10,500 years ago, because
we are exceptionally favoured, 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 liigh land
around tlie North Pole which does not encourage great
accumulations of ice. But besides this change in the re-
lation of our seasons to the earth's wphclion and 2^erih€lioii
there is another and still more important astronomical
128
ISLAND LIFE
factor in the change of magnitude of the excentricity itself.
This 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 Avas rather less than it
is now, but it then increased, and when we come to a hun-
dred thousand years ago there is a difference of eight and
a half millions of miles between our distance from the sun
in aphelion and x>CTi]idion (as the most distant and nearest
PROBABLE DURATION OF THE GLACIAL EPOCH
250 200
100 50 O
THOUSAND YEARS AGO FROM
A.D.I800.
DIAGRAM OF EXCENTRICITY AND PRECESSION.
The dark and light bands mark the phases of precession, the dark sho^ving short mild
■winters, and the light long cold winters, the contrast being greater as the excen-
tricity is higher. The horizontal dotted line shows the amount of the present
excentricity. The figures show the maxima and minima of excentricity during the
last 300,000 years from Dr. Croll's Tables. ♦
points of the earth's orbit are termed). At a hundred and
fifty thousand years 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 years ten and a half
millions of miles. By reference to the accompanying
diagram, which includes the last great period of excentricity,
we find, that for the immense period of a hundred and
sixty thousand years (commencing about eighty thousand
riTAP. VIII TIIK r-AT^^ES OF OLAflAL Kl^Or'HS i^O
years ago) the exceutricity was very great, reacliiiig a
maximum of three and a half times its present amrnuit 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 nearly twenty-eight days in excess. Now,
during all this time, our position would change, as above
described (and as indicated on the diagram), every ten
thousand live hundred years ; so that we should have
alternate periods of very long and cold winters with short
hot summers, and short mild winters with long cool
summers. In order to understand the important effects
which this would produce we must ascertain two things —
first, what actual difference of temperature would be caused
by varying distances of the sun, and, secondly, what are the
properties of snow and ice in regard to climate.
Differences of TcmiKraturc Caused hy Vary ing Distances of
the, Sicn. — On this subject comparatively few persons have
correct ideas owing to the unscientific manner in which we
reckon heat by our thermometers. The zero of Fahren-
heit's thermometer is thirty-two degTees below the freezing
point of water, and that of the centigrade thermometer,
the freezing point itself, both of which are equally
misleading 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 temi^er-
ature would fall far below either of the zero points. In
the last Arctic Expedition a temperature of— 74^F. was
registered, or 106° below the freezing 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 -f 28° F., both influencing
the temperature of the air, we may be sure that even this
intense cold was not near the possible minimum tempera-
ture. By various calculations and experiments which
cannot be entered upon here, it has been determined that
the temperature of space, independent of solar (but not of
stellar) influence, is about —239° F., and physicists almost
universally adopt this quantity in all estimates of cosmical
temperature. It follows, that if the mean temperature of
the eartli's surface at any time is 50° F. it is really warmed
130 ISLAND LIFE 1>art i
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 98 J millions of miles, whereas it
is now, in winter, only 91-^ millions of miles, the mean
distance being taken as 93 million miles. But the quantity
of heat received from the sun is inversely as the square of
the distance, so that it Avould then be in the proportion of
8,372 to 9,613 now, or nearly one seventh less than its
present amount. The mean temperature of England in
January is about 37° F., which equals 276° F. of absolute
temperature. But the above-named fraction of 276° is 237,
the difference, 89, representing the amount which must be
deducted to obtain the January temj^erature during the
glacial epoch, which will therefore be — 2° F. But this is
a purely theoretic result. The actual temperature at that
time might have been very different from this, because
the temperature 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 receiving as much sun heat as many
parts of the tropics, but we get cold winds from the
iceberg-laden North Atlantic, and this largely neutralises
the effect of the sun. So we often have it very mild in
December if south-westerly winds bring us warm moist air
from the Gulf-stream. But though the above method does
not give correct results for any one time or place, it will be
more nearly correct for very large areas, because all the
sensible surface-heat which jDroduces climates necessarily
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 winter,
at the time of the glacial epoch, the northern hei:ai-
sphere was receiving so much less heat from the sun
as was calculated to lower its surface temperature on an
average about 39° F., while during the height of summer
of the same period it would be receiving so much more
heat as would suffice, other conditions being equal, to raise
its mean temperature about 48° above what it is now.
CHAP, VIII
THE CAUSES OF GLACIAL EPOCHS 131
The winter, moreover, would be long and the summer
short, the difference being twenty-six days.
We have here certainly an amount of cold in winter
amply sufficient to produce a glacial period,^ especially as
this cold would be long continued ; but at the same time
we should have almost tropical heat in summer, although
that season would be somewhat 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 this
question we must take account of certain properties of water
and air, snow and ice, to which due weight has not been
given by Avriters on this subject.
Properties of Air and Water, Snow and Ice, in Relation to
Climate. — The great aerial ocean which surrounds us has
the wonderful property of allowing the heat-rays from the
sun to pass through it without its being warmed by them ;
but when the earth is heated the air gets warmed by con-
tact with it, and also to a considerable extent by the heat
radiated from the warm earth, because, although pure dry
1 In a letter to Nature of October 30tli, 1879, the Rev. 0. Fisher calls
attention to a result arrived at by Pouillet, that the temperature whicli the
surface of the ground would assume if the sun were extinguished would
be - 128'' F. instead of - 239° F. If this corrected amount were used in
our calculations, the January temperature of England during the glacial
epoch would come out 17° F., and this Mr. Fisher thinks not low enough
to cause any extreme difference from the present climate. In this ojiinion,
however, I cannot agree with him. On the contrary, it would, I think, be
a relief to the theory were the amounts of decrease of temperature in
winter and increase in summer rendered more moderate, since according
to the usual calculation (wlii(di I have adopted) the ditferences are un-
necessarily great, I cannot therefore think that this modification of the
temperatures, should it be ultimately proved to be correct (which is
altogether denied by Dr. Croll), would be any serious objection to tlie
adoi)tion of Dr. Croll's theory of the Astronomical and Physical causes of
the Glacial Ejjoch.
The reason of the theoretical increase of summer heat being greater than
the decrease of winter cold is because we are now nearest the sun in winter
and fartliest in summer, whereas we calculate the temperatures of tlie
glacial epocli for the phase of })recession when the aphelion was in winter.
A large part of the increase of temperature would no doubt be used uj)
in melting ice and evaporating water, so that tliere would be a much loss
increase of sensible heat ; while only a portion of the theoretical lowering
of temperature in winter would be actually produced owing to etiualising
effect of winds and currents, and the storing up of heat by the earth and
ocean.
132 ISLAND LIFE
air allows such dark heat-rays to pass freely, yet the
aqueous vapour 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, owing to the greater weight of the cooler air
which forces it up and takes its place ; and thus heat can
never accumulate in the atmosphere beyond a very mode-
rate 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 for ever dispersing it over the earth. The rain which
brings down a certain portion of heat from the atmosphere,
and v/hich 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 cur-
rents, 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 wp in evaporating water, and the vapour thus
produced is conveyed by the aerial currents to distant
countries, where, on being condensed 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 and of very dry countries generally ; while
the still more powerful influence of moving air may be
appreciated, by considering the 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 equator
where the free air and abundance of moisture exert their
beneficial influence. Were it not for the large proportion
of the sun's heat carried away by air and water the tropics
would become uninhabitable furnaces — as would indeed
any part of the earth where the sun shone brightly
throughout a summer's day.
We see, therefore, that the excess of heat derived from
the sun at any place cannot be stored up to an important
amount owing to the wonderful dispersing agency of air
CHAP. VI I r THE CAUSES OF GLACIAL EPOCHS 133
and water ; - and though some heat does penetrate the
ground and is stored up there, this is so little in proportion
to the whole amount received, and the larger part of it is
so soon given out from the surface layers, that any sur})lus
heat that may be thus preserved during one summer of the
temperate zones rarely or never remains in sufficient
quantity to affect the temperature of the succeeding
summer, so that there is no such thing as an accumulation
of earth-heat from year to year. But, though heat cannot,
cold can be stored up to an almost unlimited amount, owing
to the peculiar property water possesses of becoming solid
at a moderately low temperature ; and as this is a subject
of the very greatest importance to our inquiry — the whole
question of the possibility of glacial epochs and warm periods
depending on it — we must consider it in some detail.
Effects of Snow on Climate. — Let us then examine the
very different effects produced by water falling as a liipiid
in the form of rain, or as a solid in the form of snow,
although the two may not differ from each other more than
two or three degrees in temperature. The rain, however
much of it may fall, runs off rapidly into streams and rivers,
and soon reaches the ocean, a small portion only sinking
into the earth and another portion evaporating into the
atmosphere. If cold it cools the air and the earth some-
what while passing through or over them, but produces no
permanent effect on temperature, because a few hoars of
sunshine restore to the air or the surface-soil all the heat
they had lost. But if snow falls for a long time, the effect,
as we all know, is very different, hecausc it has no molility.
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 gi-eat 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 d(^), and
may thus form such a mass that the warmth of the whole
succeeding summer may not be able to melt it. It then
produces perpetual snow, such as we find above a certain
altitude on all the great mountains of the globe ; and when
this takes place cold is rendered i)ermanent, no am<.)unt of
134 ISLAXD LIFE part i
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 effect
this has upon climate, by a fcAv figures showing what this
amount really is. In order to melt one cubic foot of ice,
as much heat is required as would heat a cubic foot of
water from the freezing point to 176° F., or tAvo 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 ice-cold water
two feet thick to the temperature of 88° F. ; and the effect
becomes still more easily understood if we estimate it as
applied to air, for to melt a layer of ice only 1^ inches
thick would require as much heat as would raise a stratum
of air 800 feet thick from the freezing point to the tropical
heat of 88° F. ! We thus obtain a good idea, both of the
wonderful power of snow and ice in keeping down tempera-
ture, 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 become permanent. These properties would,
however, be of no avail if it were liquid, like water ; hence
it is the state of solidity and almost complete immobility
of ice that enables it to produce by its accumulation such
extraordinary effects in physical geography and in climate,
as we see in the glaciers of Switzerland and the ice-capped
interior of Greenland.
High Land and great Moisture Essential to the Initiation
of a Glacial Epoch. — Another point of great importance in
connection with this subject, is the fact, that this perma-
nent storing up of cold depends entirely on the annual
amount of snow-fall in proportion to that of the sun and
air-heat, and not on the actual cold of winter, or even on
the average cold of the year.^ A place may be intensely
cold in winter and may have a short arctic summer, yet, if
^ Dr. Croll says this "is one of the most widespread and fundamental
OHAP. VIII THE CAUSES OF GLACIAL EPOCHS 135
SO little snow falls that it is quickly melted by the return-
ing 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 ::he extreme north
of Asia and America where the winters are colder and the
summers shorter than in Greenland in Lat. G2° N., or tlian
in Heard Island and South Georgia, both in Lit. 53^ S. in
the Southern Ocean, and almost wholly covered with per-
petual snow and ice. At the " Jardin " on the Mount
Blanc range, above the line of perpetual snow, a thermo-
meter in an exposed situation marked - 6° F. as the lowest
winter temperature : while in many parts of Siberia mer-
cury freezes during 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 Expedition there is very little perpetual
snow or ice, for Captain Nares tells us that north of Haye's
Sound, in Lat. 79° N., the mountains were remarkably free
from ice-cap, while extensive tracts of land were free
from snow during summer, and covered with a rich vege-
tation with abundance of bright flowers. The reason of
this is evidently the scanty snow-fall, which rendered it
sometimes difficult to obtain enough to form shelter-banks
around the ships ; and this was north of 80° N. Lat., where
the sun was absent for 142 days.
Perpetual Snoio Noivhcre Exists on Loivlancl Areas. — It is
a very remarkable and most suggestive fact, that nowhere
in the world at the present time are there any extensive
lowlands covered with perpetual snow. The Tundras of
Siberia and the barren grounds of N. America are all
clothed with some kind of summer vegetation ;i and it is
errors within the whole range of geological climatology." The temperature
of the snow itself is, he says, one of the main factors. {Climate and
Cosmology, p. 85.) But surely the temperature of the snow must dei^end
on the temperature of the air through which it falls.
^ In an account of Prof. Nordenskjbld's recent expedition round tlie
northern coast of Asia, given in Xatn.rc, Xovember 20th, 1870, we have
the following passage, fully supporting tlie statement in the text. " Along
the whole coist, from the White Sea to Rehring's Straits, no glacier was
seen. During autumn the Siberian coast is nearly free of ice and snow.
Therc are no mountains covered all tlie year round with snow, although
136 ISL.^ND LIFE
only where there are lofty mountains or plateaus — as in
Greenland, Spitzbergen, and Grinnell's Land — that glaciers,
accompanied by perpetual snow, cover the country, and de-
scend in places to the level of the sea. In the Antarctic
regions there are extensive highlands and lofty mountains,
and these are everywhere exposed to the influence of moist
sea-air ; and it is here, accordingly, that we find the nearest
approacli to a true ice-cap covering the whole circum-
ference 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 are all very mountainous, 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 tlie
necessary 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 exception of Greenland and a few
other considerable islands, almost all water. In the
southern hemisphere the temperate zone is almost all
water, wdiile the polar area is almost all land, or is at least
inclosed by a ring of high and mountainous land. The
result is that in the north the polar area is free from any
accumulation of permanent ice (except on the highlands
of Greenland and Grinnell's Land), while in the south a
complete barrier of ice of enormous thickness appears to
surround the jDole. Dr. Croll shows, from the measured
height of numerous Antarctic icebergs (often miles in
length) that the ice-sheet from which they are the broken
outer fragments must be from a mile to a mile and a half
some of tliem rise to a height of more than 2,000 feet." It must be
remembered that the north coast of Eastern Siberia is in the area of
supposed greatest winter cold on the globe.
^ Dr. Croll objects to this argument on the ground that Greenland and
the Antarctic continent are probably lowlands or groups of islands.
iClimatc and Cosmology, Chap. V.)
CHAP. VIII THE CAUSES OF GLACIAL EPOCHS Vi7
in thickness.! As this is the thickness of the outer edo-e
of the ice it nuist be far thicker inland ; and we thus find
that the Antarctic continent is at this very time siifferincr
glaciation to quite as great an extent as we have reason to
believe occurred in the same latitudes of the northern
li^misphere 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 sea, and the extent of the ice-sheet and fioatiiHr
icebergs. The much greater quantity of ice at the south
pole is undoubtedly due to the jDresence of a large extent
of high land, which acts as a condenser, and an unbroken
surrounding ocean, which affords a constant supply of
vapour; and the effect is intensified by winter beino-
there in aphelion, and thus several days longer than
with us, while the whole southern hemisphere is at
that time farther from the sun, and therefore receives
less heat.
We see, however, that with less favourable conditions for
the production and accumulation of ice, Greenland is
•glaciated down to Lat. Gl°. What, 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 mountainous promontories far into the
temperate zone ? The comparatively small Heard Island
in S. Lat. 53° is even now glaciated down to the sea. What
would be its condition were it a northerly extension of a
lofty Antarctic continent? Wo may be quite sure that
glaciation would then be far more severe, and that an ice-
sheet corresponding to that of Greenland might extend to
beyond the parallel of 50° S. Lat. Even this is probably
much too low an estimate, for on the west coast of New
Zealand^ in S. Lat. 43° 35' a glacier even now descends to
within 705 feet of the sea-level ; and if those islands were
the northern extension of an Antarctic continent, Ave may
be pretty sure that they would be nearly in the ice-
covered condition of Greenland, although situated in the
latitude of Marseilles.
]^ "On the Glacial Epoch," by James Croll. GcoL Ma<j. July, Au£;ust
CHAP, viir THE TAUSES OE OLAr'IAE EPOrilS u^
Conditions Determining the Presence oo" Absence of Perpct-
ual Snoir. — It is clear, then, that the vicinity of a sea or ocean
to supply moisture, together with high land to serve as a
condenser of that moisture into snow, are the prime essen-
tials of a great accumulation of ice ; and it is fully in
accordance with this view that we find the most undoubted
signs of extensive glaciation in the west of Europe and tlie
east of North America, both washed by the Atlantic and
both having abundance of high land to condense the
moisture which it supplies. Without these conditions
cold alone, however great, can produce no glacial epoch.
This is strikingly shown by the fact, that in the very
coldest portions of tlie two northern continents — Eastern
Siberia and the north-western shores of Hudson's Bay —
there is no perennial covering of snow or ice whatever.
No less remarkable is the coincidence of the districts of
greatest glaciation Avith those of greatest rainfall at the
present time. Looking at a rain-map of the British Isles,
we see that the greatest area of excessive rainfall is the
Highlands of Scotland, then follows the west of Ireland,
Wales, and the north of England ; and these were glaciated
pretty nearly in proportion to the area of country over
which there is an abundant supply of moisture. So in
EurojDe, the Alps and the Scandinavian mountains have
excessive rainfall, and have been areas of excessive glacia-
tion, while the Ural and Caucasian mountains, with less
rain, never seem to have been proportionally glaciated.
In North America the eastern coast has an abundant
rainfall, and New England with North-eastern Canada
seems to have been the source of much of the glaciation
of that continent,^
^ "The general absence of recent marks of glacial action in Eastern
Europe is well known ; and the series of changes which have been so well
traced and described by Prof. Szabo as occurring in those districts seems to
leave no room for those periodical extensions of ' ice-ca})s ' witli whidi
some authors in this country have amused themselves and their readers.
Mr. Campbell, whose abilit}' to recognise the physical evidence of glaciers
will scarcely be questioned, finds quite the same absence of the proof of
extensive ice-action in North America, westward of the meridian of
Chicago." (Prof. J. AV. Judd in (/col. Mag. 1S7G, p. 535.)
The same author notes the diminution of marks of ice-action on going
eastward in th.- Alps ; and llic Altai Mountains far in ("mlral Asia show
140 ISLAND LIFE part i
The reason why no accumulation of snow or ice ever
takes place on Arctic lowlands is explained by the observa-
tions of Lieut. Payer of the 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 influence of the sun and wind. Xo replace this
would require a precipitation of snow equivalent to about
45 inches of rain, an amount which rarely occurs in low-
lands out of the tropics. In Siberia, within and near the
Arctic circle, about six feet of snow covers tlie 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 occur.
But early in June the wind usually changes to southerly,
probably the south-western anti-trades overcoming the
northern inflow ; and under its influence the snow all dis-
appears 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 remains cold, while currents of
warm air are in the highest degree effective. If, however,
they are not of sufficiently high temperature 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 alpine glaciers.
Efficiency of Astronomical Causes in Prodiicing Glacia-
tion. — Having now collected a sufficient body of facts, let
us endeavour to ascertain what would be the state to
which the northern hemisphere would be reduced by a
no signs of having been largely glaciated. "West of the Rocky Mountains,
however, in the Sierra Nevada and the coast ranges further north, signs
of extensive old glaciers again appear ; all which x>henomena are strikingly
in accordance with the theory here advocated, of the absolute dependence
of glaciation on almndant rainfall and elevated snow-condensers and,
accumulators.
CHAP. VIII THE CAUSES OF GLACIAL EPOCHS 141
high degree of excentricity and a winter in ajihelion.
Wlien the glacial epoch is supposed to have been at its
maximum, about 210,000 years ago, the excentricity was
more than three times as great as it is now, and, accordiuLC
to Dr. Croll's calculations, the mid-winter temperature ot"
the northern hemisphere would have been lowered 36' F.,
Avhile the winter half of the year would have been twenty-
six days longer than the summer half. Tliis would brim'
the January mean temperature of England and Scotland
almost down to zero or about 80° V. of frost, a winter
climate corresponding to that of Labrador, or the coast of
Greenland on the Arctic circle. But we must remember
that the summer would be very much hotter than it is
now, and the problem to be solved is, whether, supposing
the geography of the northern hemisphere to have been
identical with what it is now, the snow that fell in winter
would accumulate to such an extent that it would nut be
melted in summer, and so go on increasing year by year
till it covered the whole of Scotland, Ireland, and Wales,
and much of England. Dr. Croll and Dr. Geikie answ t-r
that it would. Sir Charles Lyell maintained that it
would only do so if geogTaphical conditions were then
more favourable than they are now ; while the late ^Ir.
Belt has argued, that excentricity alone would not produce
the eifect unless aided by increased 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 extenr^that snow and ice would be formed in the
Arctic and Antarctic reofions at the same time whether
the wmter were in iierihdion or aphelion}
The jDroblem we have now to solve is a very difficult one,
because we have no case at all parallel to it from whicli
we can draw direct conclusions. It is, however, clear from
the various considerations we have already adduced, that
the increased cold of winter when the excentricity was
great and the sun in ciphclion during that season, would
not of itself produce a glacial epoch unless the amount of
^ I have somewhat modified this whole passage in the endeavour to
represent more accurately the dilFerence between the views of Dr. CYoll and
Sir Charles Lyell.
142 ISLAND LIFE part i
vapour supjDlied for condensation was also exceptionally
great. The greatest quantity of snow falls in the Arctic
regions in summer and autumn, and with us the greatest
quantity of rain falls in the autumnal months. It seems
probable, then, that in all northern lands glaciation would
commence when autumn occurred 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 able to melt. As time went on, and the
aphelion occurred in winter, the perennial snow on the
mountains would have accumulated to such an extent as
to chill the spring and summer vaj)ours, so that they too
would fall as snow, and thus increase the amount of de-
position ; but it is probable that this would never in our
latitudes have been sufficient to produce glaciation, were
it not for a series of climatal reactions which tend still
further to increase the production of snow.
Action of Meteorological Canses in intensifying Glaciation.
— The trade-winds owe their existence to the great differ-
ence between the temperature of the equator and the
poles, Avhich causes a constant flow of air towards the
equator. The strength of this flow depends on the differ-
ence of temperature and the extent of the cooled and
heated masses of air, and this effect is now greatest be-
tween the south pole and the equator, owing to the much
greater accumulation of ice in the Antarctic regions. The
consequence is, that the south-east trades are stronger than
the north-east, 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 which 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 hemisphere, 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
CHAP. VIII THE CAUSES OF GLACIAL EPOCHS 143
partially reversed. The south polar area, having its winter
in 'pcriliclion, would probably have had less ice, while the
north-temperate and Arctic regions would have been
largely ice-clad ; and the north-east trades would therefore
be stronger than they are now. The south-westerly anti-
trades would also be stronger in the same jn-oportion, and
would bring with them a greatly increased quantity of
moisture, which is the prime necessity to produce a con-
dition 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 still further helps on the accumula-
tion of snow and ice. It is now generally admitted that
we owe much of our mild climate and our comparative
freedom from snow to the influence of the Gulf Stream,
which also ameliorates the climate of Scandinavia and
Spitzbergen, as shown by the remarkable northward cur-
vature of the isothermal lines, so that Drontheim in N.
Lat. 62° has the same mean temperature as Halifax (Nova
Scotia) in N. Lat. 45°. The quantity of heat now brought
into the North Atlantic by the Gulf Stream depends mainly
on the superior strength of the south-east trades. When
the north-east trades were the more powerful, the Gulf
Stream would certainly be of much less magnitude and
velocity ; while it is possible, as Dr. Croll thinks, that a
large portion of it might be diverted southward owing to
the peculiar form of the east coast of South America, and
so go to swell the Brazilian current and ameliorate the
climate of the southern hemisphere.
That effects of this nature would follow from any in-
crease of the Arctic, and decrease of the Antarctic ice, may
be considered certain ; and Dr. Croll has clearly shown that
in this case cause and effect act and react on each other in
a remarkable Avay. 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 the
supply of moisture. The same increase of snow and ice,
by causing tlie north-east to be stronger than tlie south-east
144 ISLAT^D LIFE
"^
trade-winds, diminishes the force of the Gulf Stream, and
this diminution lowers the temperature of the Nortli
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 supply of the
moisture carried by the anti-trades, and increasing the
temperature by means of more powerful southward ocean-
currents ; — and all this again reacts on the northern hemi-
sphere, increasing yet further the supply of moisture by
the more powerful south-westerly winds, while still fur-
ther lowering the temperature by the southward diversion
of the Gulf Stream.
Summary of PQ'inciixd Causes of Glaciation. — I have now
sufficiently answered the question, why the short hot
summer would not melt the snow which accumulated
during the long cold winter (produced by high excentricity
and winter in a])]iclion), although the annual amount of
heat received from the sun was exactly the same as it is
now, and equal in the two hemispheres. It may be well,
before going further, briefly to summarise the essential
causes of this apj)arent paradox. These are — primarily,
the fact that solar heat cannot be stored up owing 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 icej. and, in the second place,
because the two great heat-distributing agencies, the
winds and the ocean-currents, are so afifected by an
increase of the snow and ice towards one ^o\q and^its
diminution towards the other, as to help on the process
when it has once begun, and by their action and reaction
produce a maximum of effect which, without their aid,
would be altogether unattainable.
But even this does not exhaust the causes at work, all
tending in one direction. Snow and ice reflect heat to a
much greater degree than do land or water. The heat,
therefore, of the short summer would have far less eflect
than is due to its calculated amount in melting the snow,
because so much of it would be lost by reflection. A
CHAP, viir THE CAUSES OF GLACIAL EPOCHS 145
portion of the reflected heat would no doubt Avarni the
vapour in the atmosphere, but this heat would be carried
off to other parts of the earth, while a considerable portion
of the whole would be lost in space. It must also be
remembered that 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 a^ain,
there is no loss of heat on the whole ; and as this is ad-
duced over and over again as a valid argument 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 hdovj the freezing i~)oint or freezing-
would not take place. The heat liberated by freezing is,
therefore, what may be termed low-grade heat — heat
incapable of melting snow or ice ; while the heat absorbed
while ice or snow is melting is high-grade heat, such as is
capable of melting snow and supporting vegetable growth.
Moreover, the low-grade heat liberated in the formation of
snow is usually liberated high up in the atmosphere, where
it may be carried off by winds to more southern latitudes,
while the heat absorbed in melting the surface of snow and
ice is absorbed close to the earth and is thus prevented
from warming the lower atmosphere, whicli is in contact
with vegetation. The two phenomena, therefore, by no
means counterbalance or counteract each other, as it is so
constantly and superficially asserted that they do.
Effeet of Clouds and Fog in cutting off the Suns Heat. —
Another very important cause of diminution of heat during
summer in a glaciated country would be the intervention
of clouds and fogs, which would reflect or absorb a large
])roportion of the sun-heat and prevent it reaching tlio
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-clad countries has been
shown by Dr. Croll most conclusively, and lie has further
L
146 ISLAND LIFE part i
shown that the existence of perpetual snow often depends
upon it. South Georgia in the latitude of Yorkshire is
almost, and Sandwich Land in the latitude of the north of
Scotland, is entirely covered with perpetual snow ; yet in
their summer the sun is three million miles nearer the
earth than it is in our summer, and the heat actually
received from the sun must be sufficient to raise the
temperature 20° F. higher than in the same latitudes in
the northern hemisphere, were the conditions equal — in-
stead of which their summer temperature is probably full
20° lower. The chief cause of this can only be that the
heat of the sun does not reach the surface of the earth ;
and that this is the fact is testified by all Antarctic
voyagers. Darwin notes the cloudy sky and constant
moisture of the southern part of Chile, and in his remarks
on the climate and productions of the Antarctic islands he
says : " In the Southern Ocean the winter is not so
excessively cold, but the summer is far less hot (than in
the north),/c>r the clouded shy seldom alio ivs the sun to vjcirm
the ocean, itself a bad absorbent of heat ; and hence the
mean temperature of the year, which regulates the zone
of perpetually congealed under-soil, is low." Sir James
Ross, Lieutenant Wilkes, and other Antarctic voyagers
speak of the snow-storms, the absence of sunshine, and the
freezing temperature in the height of summer ; and Dr.
Croll shows that this is a constant j^henomenon accom-
panying the j)resence 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 i^roof of this important fact by comparing
the known amount of snow-fall with the equally well-
known melting power of direct sun-heat in different
latitudes. He says : '' The annual precipitation on
Greenland in the form of snow and rain, according to Dr.
Rink, amounts to only twelve inches, and two inches of
this he considers is never melted, but is carried away in
the form of icebergs. The quantity of heat received at the
^ For numerous details and illustrations see the paper — "On Ocean
Currents in Relation to the Physical Theory of Secular Changes of Climate "
— in the PMloso2)hical Magazme, 1870.
CHAP, viir THE CAUSES OF GLACIAL EPOCHS 147
equator from sunrise to sunset, if none were cut off by the
atmosphere, would melt 8 J inches of ice, or 100 feet in a
year. The quantity received between latitude G0° 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 oif by the
atmos23here, would therefore melt fifty feet of ice per
annum, or fifty times the amount of snow which falls on
that continent. What then cuts off 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 ike Influence c>f
Astronomical Causes on Climate. — Those persons who still
doubt the effect of winter in cvphclion witli a high degree
of excentricity in producing glaciation, should consider how
the condition of south temperate America at the present
day is explicable if they reject this agency. The line of
perpetual snow in the Southern Andes is so low as 6,000
feet in the same latitude as the Pyrenees ; in the latitude
of the Swiss Alps mountains only 6,200 feet high produce
immense glaciers which descend to the sea-level ; while in
the latitude of Cumberland mountains only from 3,000 to
4,000 feet high 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
tilings to whicli England and Western Europe were sub-
jected during the latter portion of the glacial epoch, when
every valley in Wales, Cumberland, and Scotland had 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
excentricity, and the winter of the southern hemisphere is
in aphelion^ The mere geographical position of tlie
southern extremity of America does not seem es])ecially
favourable to the production of such a state of glaciation.
The land narrows from the tropics southwards and termin-
ates altogether in about the latitude of Edinburgh ; the
^ Sec Darwin's NaluralisCs Voyage Hound tJic Jl'orld, 2ud Edition, jip.
244-251.
l2
148 ISLAND LIFE
mountains are of moderate height ; while during summer
the sun is three millions of miles nearer, and the heat
received from it is equivalent to a rise of 20° F. as comjDared
with the same season in the northern hemisphere. The
only important differences are : the ojDen southern ocean,
the longer and colder winter, and the general low tempera-
ture caused by the south polar ice. But the great ac-
cumulation of south polar ice is itself due to the great
extent of high land within the Antarctic circle acted ujDon
by the long cold winter and furnished with moisture by
the surrounding wide ocean. These conditions of high
land and open ocean we know did not j^revail to so great
an extent in the northern hemisphere during the glacial
ejDOch, as they do in the southern hemisphere at the
jDresent time ; but the other acting cause — the long cold
winter — existed in a far higher degree, owing to the ex-
centricity 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 we are therefore
compelled to accept it as the most probable cause of the
much greater glaciation which then prevailed.
Geo grajjl deal Ghanffcs, hoiv far a Cause of Glaeiation. —
Messrs. Croll and Geikie have both objected to the views
of Sir Charles Lyell as to the preponderating influence of
the distribution 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 lowered, 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 cur-
rents 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 imj)ossible, and that even during a period
of high excentricity there would be no glacial epochs, and
perhaps no such thing as ice anywhere produced. This
CHAi>. VIII THE CAUSES OF CLACIAL El'Orils 140
would result ft'om there being no land near the poles to
retain snow, while the constant interchange of water by
means of currents between the polar and tropical regions
would most likely prevent ice from ever forming 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 perpetual glaciation of much of the
land would result, notwithstanding that the wliole earth
should thoretically be at a somewhat higher temperaturL'.
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 enormous quantity of vapour
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 cur-
rents could not reach them, while the warm winds would
necessarily bring so much moisture that they Avould help
on instead of checking the process of ice-accumulation.
If we suppose the continents to be of the same total area
and to have the same extent and altitude of mountain
ranges as the present ones, these mountains must neces-
sarily offer an almost continuous barrier to the vapour-
bearing winds from the south, and the result would probably
be that three-fourths of the land would be in the ice-clad
condition of Greenland, while a comparatively narrow belt
of the more southern lowlands would alone afford habitable
surfaces or produce 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 Pi uicijjUs of
Geology (11th ed.Vol. i. p. 270), if somewhat modihed 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 pcrjjetual summer or an
almost universal winter. But we have seen in our sixth
chapter that there is the strongest cumidative evidence.
150 ISLAND LIFE part i
almost amounting to demonstration, that 'for all known
geological jDeriods our continents and oceans have occupied
the same general position they do now, and that no such
radical changes in the distribution of sea and land as
imagined by way of hypothesis by Sir Charles Lyell, have
ever occurred. Such an hypothesis, however, is not with-
out its use in our present inquiry, for if we obtain thereby
a cleai" conception of the influence of such great changes
on climate, we are the better able to appreciate the tendency
of lesser changes such as have undoubtedly often occurred.
Land as a Barrier to Ocean Currents. — We have seen
already the great importance of elevated land to serve as
condensers and ice-accumulators ; but there is another and
hardly less important effect that may be produced by an
extension of land in high latitudes, which is, to act as a
barrier to the flow of ocean currents. In the region with
which we are more immediately interested it is easy to see
how a comparatively slight alteration of land and sea, such
as has undoubtedly occurred, would produce an enormous
effect on climate. Let us suppose, for instance, that the
British Isles again became continental, and that this con-
tinental land extended across the Faroe Islands and Iceland
to Greenland. The whole of the warm waters of the
Atlantic, with the Gulf Stream, would then be shut out
from Northern Europe, and the result would almost cer-
tainly be that snow Avould accumulate on the high moun-
tains 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 height 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' Strait so as to unite Greenland with
Baffin's Land, thus stopping altogether the cold Arctic
current with its enormous stream of icebergs from the west
coast of Greenland. Such a change might cause a great
accumulation of ice in the higher polar latitudes, but it
CHAP. VIII THE CAUSES OF GLACIAL EPOCHS 151
would certainly produce a wonderful ameliorating effect on
the climate of the east coast of North America, and miL,dit
raise the temj^erature of Labrador to that of Scotland.
Now these two changes have almost certainly occurred,
either together or separately, during the Tertiary period,
and they must have had a considerable effect either in
aiding or checking the action of the terrestrial and astro-
nomical 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 refer to the subsidence of the Isthmus of Panama,
which has certainly happened more than once in Tertiary
times. If this subsidence 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 northern hemisphere, the
resulting glaciation might be exceptionally severe. The
effect of this change would however be neutralised 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 im-
portant effects ; and though we may admit that the astro-
nomical causes already explained were the most important
in determining the last glacial epoch, we must also allow
that geographical changes must often have had an equally
important and perhaps even a preponderating inHuence on
climate. We must also remember that changes of land
and sea are almost always accompanied by elevation or
depression of the pre-existing land : and whereas the
former produces its chief effect by diverting the course of
warm or cold oceanic currents, the latter is of not less
importance in adding to or diminishing those areas of con-
densation and ice-accumulation which, as we have seen,
are the most efficient agents in producing glaciation.
If then Sir Charles Lyell may have somewhat erred in
attaching too exclusive an importance to geographical
changes as bringing about mutations of climate, his critics
152 ISLAND LIFE
have, I think, attached far too little importance to these
changes. We know that they have always been in pro-
gress to a sufficient extent to produce important climatal
effects ; and we shall probably be nearest the truth if we
consider, that great extremes of cold have only occurred
when astronomical and geographical causes were acting in the
same direction and thus produced a cumulative 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 attempt to prove in our next chapter.^
On the Theory of Inter- glacial Periods and their ProhaUe
Character. — The theory by which the glacial epoch is here
explained is one which apparently necessitates repeated
changes from glacial to warm periods, with all the conse-
quences and modifications both of climate and physical
geography which follow or accompany such changes. It is
essentially a theory of alternation; and it is certainly
^ The influence of geographical changes on climate is now hekl by
many geologists who oppose what they consider the extravagant hypotheses
of Dr. Croll, Thus, Prof, Dana imputes tlie glacial epoch chiefly, if not
wholly, to elevation of the land caused by the lateral pressure due to
shrinking of the earth's crust that has caused all other elevations and
depressions. He says : " Now, that elevation of the land over the higher
latitudes which brought on the glacial era is a natural result of the same
agency, and a natural, and almost necessary, counterpart of the coral-island
subsidence which must have been then in progress. The accumulating,
folding, solidification, and crystallisation of rocks attending all the rock-
making and mountain-making through the Palteozoic, Mesozoic, and
Cenozoic eras, had greatly stiffened the crust in these parts ; and hence in
after times, the continental movements resulting from the lateral pressure
necessarily appeared over the more northern portions of the continent,
where the accumulations and other changes had been relatively small. To
the subsidence which followed the elevation the weight of the ice-cap may
have contributed in some small degree. But the great balancing move-
ments of the crust of the continental and oceanic areas then going forward
must have had a greatly jireponderating effect in the oscillating agency of
all time — lateral pressure within the crust." [American Jour7ial of Science
and Arts, 3rd Series, Vol. IX. p. 318.)
*' In the 2nd edition of his Manual of Geology, Professor Dana suggests
elevation of Arctic lands sufficient to exclude the Gulf Stream, as a source
of cold during glacial epochs. This, he thinks, would have made an
epoch of cold at any era of the globe. A deep submergence of Behring's
Strait, letting in the Pacific warm current to the polar area, would have
produced a mild Arctic climate like that of the Miocene period. When
the warm current was shut out from the polar area it would yet reach
near to it, and bring with it that abundant moisture necessary for glacia-
tion." {Manual of Gcologji, 2nd Edition, pj). 541-755, 756.)
CHAP. VIII THE CAUSES OF GLACIAL EPOCHS 153
remarkable in how many cases geologists have independ-
ently deduced some alternations of climate as probjible.
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 jii'^sent 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 not long after the period of
extreme glaciation.
But although the evidence of so7«<? alternations of climate
seems indisputable, and no suggestion of any adequate
cause for them other than the alternating phases of
precession during high excentricity 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 throughout the wdiole year.
It is quite evident that during the height of the glacial
epoch there was a combination of causes at work wdiich led
to a large portion of North-western Europe and Eastern
America being buried in ice to a greater extent even than
Greenland is now, since it certainly extended beyond the
land and filled up all the shallow seas between our islands
and Scandinavia. Among these causes Ave must reckon a
diminution of the force of the Gulf Stream, or its being
diverted from the north-Avestern coasts of Europe; and
what we have to consider is, whether the alteration from
a long cold winter and short hot summer to a short
mild winter and long cool summer would greatly affect
the amount of ice if the ocean currents remained the
same. The force of these currents is, it is true, by our
hypothesis, modified by the increase or diminution of the
ice in the two hemispheres alternately, and they then
react upon climate ; but they cannot be thus changed till
after the ice-accumulation has been considerably affected
by other causes. Their direction may, indeed, be greatly
154 ISLAND LIFE
changed by slight alterations in the outline of the land,
while they may be barred out altogether by other alterations
of not very great amount ; but such changes as these have
no relation to the alteration of climates caused by the
changing phases of precession.
Now, the existence at the present time of an ice-clad
Greenland is an anomaly in the northern hemisphere, only
to be explained by the fact that cold currents from the
polar area flow down both sides of it. In Eastern Asia we
have the lofty Stanivoi Mountains in the same latitude as
the southern part of Greenland, which, though their
summits are covered with perpetual snow, give rise to no
ice-sheet, and, apparently, even to no important glaciers ;
— a fact undoubtedly connected with the warm Japan
current flowing partially into the Sea of Okhotsk. So in
North-west 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 the north and north-west,
with glaciers comparable in size with those of New Zealand,
although situated in Lat. 60° instead of in Lat. 45°. Here,
too, we have the 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 be completely forest-
clad and inhabitable ; while, if the Japan current were to
be diverted from the coast of North America and a cold
current come out of Behring's Strait, the entire north-
western extremity 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 North-eastern
America was considerably elevated.^ This elevation would
brino" 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 600 miles east of
Halifax ; and this would certainly divert much of the
greatly reduced Gulf Stream straight across to the coast of
1 Dana's Manual of Geology, 2n(i Edition, p. 540.
CHAP. VIII THE CAUSES OP GLACIAL EPOCHS 155
UKl
Spain. The consequence of sucli a state of tilings wo
probably be that the southward flowing Arctic current
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 witli
a dense ice-pack, equalling that of the Antarctic regions,
and chilling the atmosphere so as to produce constant
clouds and fog with almost perpetual snowstorms, 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,
however caused, such must have been its state during the
height of the 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— thc^^hysical and gcogrcqiliical causes of glaciation
remaining unchanged? For, certainly, the less powerful
sun of summer, even though lasting somewhat longer,
could not do more than the much more poAverful sun did
during the phase of summer in jjcrihelion, wdiile during the
less severe winters the sun would have far less power than
when it was equally near and at a very much greater
altitude in summer. It seems to me, therefore, quite
certain that whenever extreme glaciation has been brought
about by high excentricity combined with favourable
geographical and physical causes (and without this combina-
tion it is doubtful whether extreme glaciation woidd ever
occur), then the ice-sheet will net be removed during the
alternate phases of precession, so long as these geographical
and physical causes remain unaltered. It is truethat the
warm and cold oceanic currents, which are the most
important agents in increasing or diminishing glaciati(^n,
depend for their strength and efficiency upon the compara-
tive extents of the northern and southern ice-sheets ; but
these ice-sheets cannot, I believe, increase or diminish to
any important extent unless some geographical or physical
change first occurs.^
' Dr. Croll says that I here a^-suine an inijtossiMe sta(<> f»f tliiiius. He
iiiaintaius "that the cliange from the distant sun in winter, and near siui
156 ISLAND LIFE
If this argument is valid, then it would follow that, so
long as excentricity was high, whatever condition ^ of
climate was brought about by it in combination with
geographical causes, would persist through several phases
of precession ; but this would not necessarily be the case
when the excentricity itself changed, and became more
moderate. It would then depend upon the proportionate
effect of climatal and geographical causes in producing
glaciation as to what change would be produced by the
changing phases of precession ; and we can best examine
this question by considering tbe probable effect of the
change in precession during the next period of 10,500
years, with the present moderate degree of excentricity.
Prolctbh Effect of Winter in Aphelion on the Climate of
Britain. — Let us then suppose the winters of the northern
hemisphere to become longer and much colder, the
in summer to the near sun in winter and distant sun in summer, aided by
the change in the physical causes which this would necessarily bring about,
would certainly be sufficient to cause the snow and ice to disappear."
{Climate and Cosmology, p. 106.) But I demur to his "necessarily." It
is not the direct etiect of the nearer sun in winter that is supposed to melt
the snow and ice, but the "physical causes," such as absence of fogs and
increase of warm equatorial currents. But the near sun in winter acting
on an ice-clad surface would only increase the fogs and snow, while the
currents could only change if a large portion of the ice were first melted,
in which case they would no doubt be modified so as to cause a further
melting of the ice. Dr. Croll says: "The warm and equable conditions
of climate which would then prevail, and the enormous quantity of
intertropical water carried into the Southern Ocean, would soon produce a
melting of the ice." [Loc. cit. p. 111.) This seems to me to be assuming the
very point at issue. He has himself shown that the presence of large
quantities of ice prevents "a warm and equable climate" however great
may be the sun-heat ; the ice therefore would not be melted, and there
would be no increased flow of intertropical water to the Southern Ocean.
The ocean currents are mainly due to the diff"erence of temperature
of the polar and equatorial areas combined with the peculiar form and
position of the continents, and some one or more of these factors must
be altered before the ocean currents towards the north pole can be
increased. The only factor available is the Antarctic ice, and if this
were largely increased, the northward-flowing currents might be so
increased as to melt some of the Arctic ice. But the very same argument
applies to both poles. Without some geographical change the Antarctic
ice could not materially diminish during its winter in perihelion, nor in-
crease to any important extent during the opposite phase. We therefore
seem to have no available agency by which to get rid of the ice over a
glaciated hemisphere, so long as the geographical conditions remained
unchanged and the excentricity continued high.
CHAP. VIII THE CAUSES OF GLACIAL EPOCHS 157
summers being proportionately sliorter and liotter, without
any other change whatever. The long cold winter would
certainly bring down the snow-line consideraljly, covering
large areas of high land with snow during tlie winter
months, and causing all glaciers and ice-fields to become
larger. This would chill the superincumbent atmospliere
to such an extent that the warm sun and winds of sprino-
and early summer would bring clouds and fog, so tliat tlie
sun-heat would be cut off and mucli vapour be condensed
as snow. Tlie 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 Avould not be all
melted, and that therefore the snow-line would be per-
manently lowered. This would be a necessary 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 inter-
vention 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 winter will occur in (q)JicI ion {instead
of, as now, in jKrihelion), there will be produced a colder
climate, independently of any change of land and sea, of
heights of mountains, or in the force of oceanic 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 2:)hysical conditions
remaining unchanged), would certainly bring back again
our present milder climate. The change either way would
not probably be very great, but it might be sufficient to
bring the snow-line down to 3,000 feet in Scotland, so that
all the higher mountains would have their to])s covered
with periictual snow. This pei-petual snow, down to a
lixed line, would be kept up by the needful su])]»ly (.fsnow
falling during autumn, winter, and sj^ring, and this Avould,
as we have seen, depend mainly on the increased length
and greatly increased cold of the winter. As both the dura-
tion and the cold of winter decreased the amount of snow
w^ould certainly decrease, and of this lessor ijuantity of sn»tw
158 ISLAND LIFE part i
a larger proportion would be melted by the longer, though
somewhat cooler summer. This would follow because the
total amount of sun-heat received during the summer
would be the same as before, while it would act on a less
quantity of snow ; there would thus be a smaller surface to
reflect the heat, and a smaller condensing area to produce
fogs, while the diminished intensity of the sun would
produce a less dense canopy of clouds, which have been
shown to be of prime importance in checking the melting
of snow by the sun. We have considered this case, for
simplicity of reasoning, on the supposition that all geo-
graphical and physical causes remained unchanged. But
if an alteration of the climate of the whole north temperate
and Arctic zones occurred, as here indicated, this would
certainly affect botli the winds and currents, in the manner
already explained {sec p. 142), so as to react upon climate
and increase the differences produced by phases of
precession. How far that effect would be again increased
by corresponding but opposite changes in the southern
hemisphere it is impossible to say. It may be that
existing geographical 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, as the climate of the whole southern
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 already fully explained.
The Essential rrinciplc of Climatal Change Restated. —
The preceding discussion has been somewhat lengthy,
owing to the varied nature of the facts and arguments
adduced, and the extreme complexity of the subject. But
if, as I venture to urge, the principle here laid down is a
sound one, it Avill be of the greatest assistance in clearing
away some of the many difficulties that beset the whole
question of geological climates. This principle is, briefly,
that the great features of climate are determined by a
combination of causes, of which geographical conditions
and the degree of excentricity of the earth's orbit are by
CHAP, viir THE CAUSES OF GLACIAL EPOCHS 159
far the most important; that, when these combine to pro-
duce a severe glacial epoch, the changing phases of pre-
cession every 10,500 years have very little, if any, effect on
the character of the climate, as mild or glacial, though it
may modify the seasons; but when the excentricity be-
comes moderate and the resulting glaciation less severe,
then the changing phases of precession bring about a con-
siderable alteration, and even a partial reversal of the
glacial conditions.
The reason of this may perhaps be made clearer by con-
sidering the stability of either extreme glacial conditions
or the entire absence of perpetual ice and snow, and the
comparative instability of an intermediate state of climate.
When a country is largely covered with ice, we may look
upon it as possessing the accumulated or stored-up cold of
a long series 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 off 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 ex-
posed earth becomes heated by the hot sun, this warms
the air, and the warm air melts the adjacent ice. It fol-
lows, that towards the equatorial limits of a glaciated
country alternations of climate may occur during a period
of high excentricity, while nearer the pole, where the sur-
face is almost completely ice-clad, no amelioration may
take place. The same argument Avill, to some extent
apply, inversely, with mild Arctic climates ; but this is a
subject which will be discussed in the next cha])ter.
This view of the character of the last glacial e])och ap-
pears to correspond very closely 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 verv latest
160 ISLAND LIFE
of them, which we may suppose to have occurred when the
excentricity was considerably diminished, that exhibit any
indications of a cUmate at all warmer than that which now
prevails.^
Probable Date of the Glacial E]Jocli. — The state of extreme
glaciation in the northern hemisphere, of which we gave
a general description at the commencement of the pre-
ceding chapter, is a fact of which there can be no doubt
whatever, and it occurred at a period so recent geologically
that all the mollusca were the same as species 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,
^ In the Geological Marjazinc, April, 1880, Mr. Seaiies V. Wood
adduces what he considers to be the " conclusive objection" to Dr. Croll's
excentricity theory, which is, that during the last glacial epoch Europe
and North America were glaciated very much in jjroportion to their
respective climates now, which are generally admitted to be due to the
distribution of oceanic currents. But Dr. Croll admits his theory "to
be baseless unless there was a comjilete diversion of the warm ocean
currents from the hemisphere glaciated," in which case there ought to be
no difference in the extent of glaciation in Europe and North America.
Whether or not this is a correct statement of Dr. Croll's theory, the above
objection certainly does not apply to the views here advocated ; but as I
also hold the "excentricity theory" in a modified form, it may be as well
to show why it does not apply. In the first place I do not believe that the
Gulf Stream was "completely diverted" during the glacial epoch, but
that it was diminished in force, and (as described at p. 144) ;xi?'(!?2/ diverted
southward. A portion of its influence would, however, still remain to
cause a difference between the climates of the two sides of the Atlantic ;
and to this must be added two other causes — the far greater penetration
of warm sea-water into the European than into the North American conti-
nent, and the proximity to America of the enormous ice-producing mass
of Greenland. We have thus three distinct causes, all combining to
produce a more severe winter climate on the west than on the east of the
Atlantic during the glacial epoch, and though the first of these — the Gulf
Stream — was not nearly so powerful as it is now, neither is the difterence
indicated by the ice-extension in the two countries so great as the present
difference of winter-temperature, Avhich is the essential point to be con-
sidered. The ice-sheet of the United States is usually supposed to have
extended about ten, or, at most, twelve, degrees further south than it did
in Western Europe, whereas Ave must go twenty degrees further south in
the former country to obtain the same mean winter-temperature Ave find
in the latter, as may be seen by examining any map of Avinter isothermals.
This difference very fairly corresponds to the difference of conditions
existing during the glacial epoch and the ])resent time, so far as Ave are
able to estimate them, and it certainly affords no grounds of objection to
the theory by Avhich tlie glaciation is here ex-2)lained.
CHAP, viir THE CAUSES OF GLACIAL EPOCHS 161
while on the other hand the surface markings produced
by the ice have been extensively i^reserved ; and takin^;
all these facts into consideration, the period of about
200,000 years since it reached its maximum, and al)()ut
80,000 years since it passed away, is generally considered
by geologists to be ample. There seems, therefore, to be
little doubt that in increased excentricity 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 consider-
able probability of being correct. The enormous duration
of the glacial epoch itself (including its interglacial mild
or warm phases), as compared with the lapse of time since
it finally passed away, is a consideration of the greatest
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 dependent on, it.
Changes of the Sea-level Dependent on Glaciation. — It has
been pointed out by Dr. Croll, 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 liave 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. Extreme 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 however believed to exist on tlie Antarctic pole
at the present day, and its transference to the northern
hemisphere would, it is calculated, produce a rise of the
ocean to the extent of 800 or 1,000 feet. We have, liow-
cvcr, shown that the production of any sucli ice-cap is
improbable if not impogsible, because sikjw and ico r.-m
M
162 ISLAND LIFE pakt i
only accumulate where precipitation is greater tlian melt-
ing and evaj)oration, and this is never the case except in
areas exposed to the full influence of the vapour-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 hot days of summer."^ The
accumulations of ice were therefore probably confined, in
the northern hemisphere, to the coasts exposed to moist
winds, and where elevated land and mountain ranges
afforded condensers to initiate the process of glaciation :
and we have already seen that the evidence strongly sup-
ports this view. Even with this limitatiou, however, the
mass of accumulated ice would be enormous, as indeed we
have positive evidence that it was, and might have caused
a sufficient shifting of the centre of gravity of the eartli to
produce a submergence of about 150 or 200 feet.
But this would only be the case if the accumulation of
ice on one pole was accompanied by a diminution on the
other, and this may have occurred to a limited extent
during the earlier stages of the glacial epoch, when alter-
nations of warmer and colder periods would be caused by
winter occurring m 2^i'yi1(dion or (qjhdioii. If, however, as
is here maintained, no such alternations occurred when
the excentricity was near its maximum, then the ice
would accumulate in the southern hemisphere at the Fame
time as in the northern, unless changed geographical condi-
tions, of which we have no evidence Avhatever, prevented
such accumulations. That there was such a greater ac-
cumulation 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 in-
dications in all these localities point to a period so recent
that it must almost certainly have been contemporaneous
with the glacial period of the northern hemisphere.-
^- Dr. Croll objects to this argument, and adduces the case of Greenland
as showing tliat ice may accumulate far from sea. But tlie width of
Greenland is small compared with that of the supposed Antarctic ice-cap.
{Climate and Cosmology, p. 78.)
2 The recent extensive glaciation of Xew Zealand is generally imputed hv
the local geologists to a greater elevation of the land ; hut I rannot helj.
THE CAUSES OF GLACIAL EPOCHS 163
I,
This greater accumulation of ice in both hemispheres
would lower the whole ocean by the quantity of water
Ixdieving that the liigli phase of cxcentricity Avhich caused our own ghicial
epoch was at all events an assisting cause. This is rendered more proh-
aldc if taken in connection with the following very definite statement of
glacial markings in South Africa, Captain Aylward in his Transvaal of
To-daji (p. 171) says : — "It will be interesting to geologists and others to
learn that the entire country, from the summits of the Quathlamba to the
junction of the Vaal and Orange rivers, shows marks of having been swept
over, and that at no very distant period, by vast masses of ice from east to
west. The striations are plainly visible. scarring the older rocks, and marking
the hill-sides— getting lower and lower and less visible as, descending from
the mountains, the kopjies (small hills) stand wider apart ; but wherever
the hills narrow towards each other, again showing how the vast ice-fields
were checked, thrown up, and raised against their Eastern extremities."
This jiassage is evidently written by a i)crson familiar with the phe-
nomena of glaciation, and as Captain Aylward's preface is dated from
Edinburgh, he has probably seen similar markings in Scotland. The
country described consists of the most extensive and lofty plateau in South
Africa, rising to a mountain knot with peaks more than 10,000 feet high,
thus otiering an appropriate area for the condensation of vapour 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 nnich higher in
recent times, since the coast of Natal is now said to be rising. It is evi-
dent that no slight elevation would now lead to the accumulation of snow
and ice in these mountains, situatcdas they are between 27° and 30° S. Lat. ;
since the Andes, which in 32° S. Lat. reach 23,300 feet liigh, and in 28"
S. Lat, 20,000, with far more extensive plateaus, produce no ice-fields.
"We cannot, therefore, believe that a few thousand feet of additional eleva-
tion, even if it occurred so recently as indicated by the presence of stria-
tions, would have produced the remarkable amount of glaciation above
described ; while from the analogy of the northern hemisphere, we may
well lielieve that it was mainly due to the same high cxcentricity 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 jniper
published in X\\q Qua rtcrhj Journal of the Gcolorjkal Sodcty [\o\. xxvir, p.
r)39), describes similar X)henomena in the same mountains, and also uiounds
and ridges of unstratified clay packed with angular boulders ; while further
south the Stormberg mountains are said to be similarly glaciated, with im-
mense accumulations of morainic matter in all the valleys. "We have here
most of the surface i)henomena characteristic of a glaciated country, only
a few degrees south of the troi)ic ; and taken in connection with the indica-
tions of recent glaciation in New Zealand, and those discovered by Dr. K.
von Lendenfeld in the Australian Alps between G,000 and 7,000 feet ele-
vation [Xaturc, Vol. xxxir. p. 69), wc can hardly doubt the occurrence of
some giaieral and wide-spread cause of glaciation in the southern hemisphere
at a period so recent that the superficial phenomena are almost as well \>\o-
served as in Europe. Other geologists however deny that there are any
distinct indications of glacial action in South Africa ; but the recent dis-
covery by Dr. J. W. Gregory, F.G.S., of the former extension of glaciers
on :\Ioun"t Kenya 5,000 feet below their i)resent limits, renders prol»al)lc
the former glaciation of the South African Highlands.
M '1
164 ISLAND LIFE takt i
abstracted from it, Avhile 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 other. It is also generally believed that a great
accumulation of ice would cause subsidence by its pressure
on the flexible crust of the earth, and we thus have a ver}'
complex series of agents leading to elevations and sub-
sidences of limited amount, such as seem always to have
accompanied glaciation. This complexity of the causes at
work may explain the somewhat contradictory evidence as
to rise and fall of land, some authors maintaining that
it stood higher, and others lower, during the glacial
period.
The State of the Planet Mars, as Bearing on the Theory of
Excentrieity as a Cause of Glacial Ferioels.— It is well known
that the polar regions of the planet Mars are covered with
white patches or discs, which undergo considerable altera-
tions of size according as they are more or less exposed to
the sun's rays. They have therefore been generally con-
sidered to be snow or ice-caps, and to prove that Mars is
now undergoing something like a glacial period. It must
always be remembered, how^ever, that we are very ignorant
of the exact physical conditions of the surface of Mars.
It appears to have a cloudy atmosphere like our own, but
the gaseous composition of that atmosphere may be dif-
ferent, and the clouds may be formed of other matter
besides aqueous vapour. Its much smaller mass and
attractive pow^r must have an effect on the nature and
extent of these clouds, and the heat of the sun may con-
sequently be modified in a Avay quite different from any-
thing that obtains upon our earth. Bearing these diffi-
culties and uncertainties in mind, let us see what are the
actual facts connected w^ith the sui^jjosed polar snow^s of
Mars.V
^ The astronomical facts connected with the motions and appearance of
the planet are taken from a paper by Mr. Edward Carpenter, M.A., in the {
Geological Magazine of March, 1877,'^ entitled, " Evidence Afforded hy Mars |
on the Subject of Glacial Periods," but I arrive at somewhat different con- ,
OHAr. VIII THE CAUSES OF GLACIAL EPOCHS
Mars ofters an excellent subject for comparison wiih th.^
Earth as regards this question, because its exccntricitv is
now a little greater than the maximum excentricity of tho
Earth during the last million years, — (Mars excentricity
001)81, Earth excentricity, 850,000 years back, O-oTOTj ;
tlie inclination of its axis is also a little greater than ours
(Mars 2cS° 51', Earth 23° 27'), and both Mars and the Earth
are so situated that they now have the winter of their
northern hemispheres in j^criJirliou, that of their scnitheru
hemisphere being in aphrlwn. If, therefore, the physical
condition of Mars were the same or nearly the same as that
of the Earth, all circumstances combine, according to ]3r.
Croll's hypothesis, to produce a severe glacial epoch in its
southern, with a perpetual spring or summer in its northern,
hemisphere; while on the hypothesis here advocated we
should expect glaciation 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 unecpially. The
northern cap varies slowly and little, the soutliern \'aries
rapidly and largely.
h\ the year lcS.30 iha soutltern ^novi 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 etpiivalent to
one-twelfth of a Martian year). Thus on June 23rd it
was^ll° 30' in diameter, and on July 9th had diminished
to 5° 4G', 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 tlie same year the northrni snow-cap was observed
during its summer, and was found to vary as follows : —
Mav 4tl..
.Iiiiic 4tli.
„ 1711. .
Jnlv 4tli.
,,' 12th.
,, 20th.
liamctt-:
r of spot
31° 24'
28° 0'
22' 54'
18° 24'
15° 20'
IS^ 0'
We thus see that Mars has two permanent snow-caps, of
nearly equal size in winter but diminishing very unequallv
166 ISLAND LIFE pakt i
in summer, when the southern cap is reduced to nearly
one third the size of the northern ; and this fact is held
by Mr. Carpenter, as it was by the late Mr. Belt, to be
opposed to the view of the hemisphere which has winter in
aphelion (as the southern now has both in the Eartli and
Mars), having been alone glaciated during periods of high
excentricity.^
Before, however, we can draw any conclusion from the
case of Mars, we must carefully scrutinise the facts, and
the conditions they imply. In the first place, there is
evidently this radical difference between the state of Mars
now and of the Earth during a glacial period — that Mars
has no great ice-sheets spreading over its 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 about 100 miles of our measure), and in the northern
hemisi^here of eight degrees wide (about 280 miles) be-
tween May 4th and July 12th. Even with our mucli
more powerful sun, which gives us more than twice as
much heat as Mars receives, no such diminution of an ice-
sheet, or of glaciers of even moderate thickness, could
possibly occur ; but the phenomenon is on the contrary
exactly analogous to what actually takes place on the plains
of Siberia in summer. These, as I am info'rmed by Mr.
Seebohm, are covered with snow during winter and spring-
to a depth of six or eight feet, which diminishes very little
even under the hot suns of May, till warm winds combine
with the sun in June, when in about a fortnight the whole
of it disappears, and a little later the whole of northern
Asia is free from its winter covering. As, however, the
sun of Mars is so much less powerful than ours, ^\e may be
^ lu an article in iVrt^urc of Jan. 1, 1880, the Rev. T. W. "Webb states that
in 1877 the pole of Mars (? the sonth pole) was, according to Schiaparelli,
entirely free of snow. He remarks also on the regular contour of the sup-
posed snows of Mars as otfcring a great contrast to ours, and also the
strongly marked dark border which has often been oliserved. On the whole
Mr. Webb seems to be of opinion that there can be no really close resem-
blance between the physical condition of the Earth and Mars, and that
any arguments founded on such supposed similarity are therefore untrust-
worthy.
CHAP. VIII THE CAUSES OF GLACIAt EPOCHS 167
sure that tlio snow (if it is real snow) is much less thick
— a mere smface-coating in fact, such as occurs in parts
of Russia Avhere the i^recipitation is less, and the snow
accordingly does not exceed two or three feet in tliickness.
We now see the reason why the soutlicrn pole of ^[ars
parts with its white covering so much more rpiickly and to
so much greater an extent than the northern, for the south
jjole during summer is nearest the sun, and, owing to the
great excentricity of Mars, would have ahout one-third
more heat than during the summer of the northern hcnii-
sphere ; and this greater heat would cause the winds tVom
the ecpiator to be both warmer and more powerful, and able
to produce the same effects on the scanty Martian snows as
they produce on our northern snow-plains. The reason
why both poles of Mars are almost equally snow-covered in
winter is not difficult to understand. Owing to the greater
obliquity of 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 the 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
geographical features, and that neither of them is sur-
rounded by very high land on which ice may accumulate.
With us at the present time, on the other hand, geograph-
ical conditions completely mask and even reverse tlie
influence of excentricity, and that of winter in |7r?77R7/o?^
in the northern, and summer m ■pcrihrlion in the southern,
hemisphere. In the north we have a preponderance of
sea within the Arctic circle, and of lowlands in the temperate
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 coating of snow, easily melted in summer, is
the prevalent feature in the north ; and these contrasts
react upon climate to such an extent, that in the southern
ocean, islands in the latitude of Ireland have glaciers
descendini^ to the level of the sea, and constant snowstorms
168 ISLAND LIFE
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 ]\lars 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 j^rinciples, if we keep in
mind tlie distinction between an ice-sheet — which a
summer's sun cannot materially diminish, but may even
increase by bringing vapour to be condensed into snow —
and a thin snowy covering which may be annually melted
and annually renewed, with great rapidity and over large
areas. Except witliin 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 may be partly due to higher land at the
north, but is perhaps sufficiently explained by the dimi-
nished power of the summer sun, owing to its greatly
increased distance at that season in the northern hemi-
sphere, so that it is not able to melt so much of the snow
which has accumulated durino- the lon^- nisfht of winter.
CHAPTER IX
ANriENT OLACIAL EPOCHS, AND MILD TLnfATES IX THE
AKCTIC REGIONS
Dr. C'roll's Views on Ancient Glacial Epochs — Ellects of Denudation in
Destroying the Evidence of Remote Glacial Epochs — Rise of Sea-level
Connected with Glacial Ejiochs a Cause of Further Denudation— What
Evidence of Ivirly Glacial Epochs may be Expected — Evidences of Ice-
action During the Tertiary Period — The "Weight of the Negative Evi-
dence— Temperate Climates in the Arctic Regions — The ]\Iiocene Arctic
Flora — ]\Iild Arctic Climates of the Cretaceous Period — Stratigi'aphical
Evidence of Long-continued ]\Iild Arctic Conditions — The Causes of JNlild
Arctic Climates — Geographical Conditions Favouring ^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
— Elfect of High Excentricity on "Warm Polar Climates — Evidences as to
Climate in the Secondary and Palaeozoic Epoehs — "Warm Arctie Climate.-s
in Early Secondary and Paliieozoic Times — Con(dusions 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 Pro-
ducing Changes of Climate.
If we adopt tlie view set forth in the preceding chapter as
to the character of the glacial epoch and of the accom-
panying alternations of climate, it mnst have been a very
important agent in producing changes in the distribution
of animal and veo'etable life. The intervening niil<l
. . ...
periods, which almost certainly occurred during its earlier
and later phases, may have been sometimes more equable
than even our present insular climate, and severe frosts
were probably then unknown. Pnriiig tlio four or five
170 ISLAND LIFE
thousand 3^ears that each specially mild period may liave
lasted, some portions of the north temiDerate zone, which
had been buried in snow or ice, would become again
clothed with vegetation and stocked wath animal life, both
of which, as the cold again came on, w^ould be driven
southw^ard, or perhaps j^artially exterminated. Forms
usually separated would thus be crowded together, and a
struo-oie for existence woidd follow, which must have led
to the modification or the extinction of many species.
When the survivors in the struggle had reached a state of
equilibrium, afresh field would be opened to them by the
later ameliorations of climate ; the more successful of the
survivors Avoidd spread and multiiDly ; and after this had
gone on for tliousands of generations, another change of
climate, another southward migration, 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 excen-
tricity of the earth's orbit, we are naturally led to expect
that earlier glacial epochs would have occurred whenever
the excentricity was unusually large. _- Dr. CroU has
published tables showing the varying amounts of excen-
tricity for three million years back ; and from these it
appears that there have been many periods of high excen-
tricity, 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 excentricity occurred 850,000 years ago, at which
tmie the difference between the sun's distance at aphelion
and perihelion was thirteen and a half millions of miles,
whereas during the last glacial period the maximum
difference was ten and a half million miles.
Now, 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 ejccentricity
coincided wdth some part of the latter period ; and Dr.
Croll maintains that a glacial epoch must then have
^ London, Edinburgh andDuhlin PhiJosoplncd Magazine, A'ol. XXXVI.,
pp. 144-150 (1868).
AXriEXT OLACIAL EPOCHS
171
occurred surpassing in severity
that of wliicli we liave sucli con-
vincing proofs, and consisting like
it of alternations of cold and
warm phases every 10,500 years.
The diagram also shows us another
long-continued period of high ex-
centricity from 1,750,000 to
1,950,000 years ago, and yet
another almost equal to the maxi-
mum 2,500,000 years back. These
ma}^ perhaps have occurred during
the Eocene and Cretaceous epochs
respectively, or all may have been
included within the limits of the
Tertiary period. As two of these
hioh excentricities o-reatlv exceed
that which caused our glacial
epoch, while the third is almost
equal to it and of longer duration,
they seem to afford us the means
of testing rival theories of the
causes of glaciation. If, as Dr.
Croll argues, high excentricity is
the great and dominating agency
in bringing on glacial epochs, geo-
graphical changes being subor-
dinate, then there must have
been glacial epochs of great
severity at all these three periods ;
while if he is also correct in sup-
posing that the alternate phases
of precession Avould inevitably
produce glaciation in one hemi-
sphere, and a proportionately
mild and equable climate in tlie
opposite hemisphere, then we
should have to look for evidence
of exceptionally warm and excep-
tionally cold periods, occurring
/
172 ISLAND LIFE
alternately and with several repetitions, within a space of
time which, geologically speaking, is very short indeed.
Let us then intpiire first into the character of the
evidence we should expect to find of such changes of
climate, if they have occurred ; we shall then be in a
better position to estimate at its proper value the evidence
that actually exists, and, after giving it due weight, to
arrive at some conclusion as to the theory that best
explains and harmonises it.
Effects of Denudation in Destroying the Emdencc of Remote
Glacicd Epochs. — It may be supposed, that if earlier glacial
epochs than the last did really occur, we ought to meet
with some evidence of the fact corresponding to that which
has satisfied us of the extensive recent glaciation of the
northern hemisphere ; but Dr. CroU and other writers have
ably argued that no such evidence is likely to be found.
It is now generally admitted that sub-aerial denudation is
a much more powerful agent in lowering and modifying
the surface of a country than was formerly supposed. It
has in fact been proved to be so powerful that the diffi-
culty now felt is, not to account for the denudation which
can be proved to have occurred, but to explain 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 understand, is to be found in
the quantity of solid matter carried down to the sea and to
low grounds by rivers. This is capable of pretty accurate
measurement, and it has been carefully measured for
several rivers, large and small, in different parts of the
world. Tlie details of these measurements will be given
in a future chapter, and it is only necessary here to state
that the averao'e of them all oives us this result — that one
foot must, on an average, be taken off the entire surface of
the land each 3,000 years in order to produce the amount
of sediment and matter in solution which is actually carried
into the sea. To give an idea of the limits of variation in
different rivers it may be mentioned that the Mississippi is
one which denudes its valley at a slow rate, taking 6,000
ANCIENT GLACIAL EPOCHS 173
3^ears to remove one foot ; while the Po is tlic most rapid,
taking only 720 years to do the same work in its valley.
The cause of this difference is very easy to understand.
A large part of the area of the Mississippi basin consists of
the 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 23lateau. The Po..
on the other hand, is wholly in a district of abundant rain-
fall, while its sources are spread over a great amjjhitheatre
of snowy Alps nearly 400 miles in extent, where the
demiding forces are at a maximum. As Scotland is a
mountain region of rather abundant rainfall, the denuding
l>ower 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 4,000 years.
Now if the end of tlie glacial epoch be taken to coin-
cide with the termination of the last period of higli
excentricity, 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 Avherever the rivers have spread during
floods, the ground will have been raised instead of lovv^ered ;
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 denudation, ]\Ir.
Archibald Geikie, estimates the area of these more rapidly
denuded portions as only 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 vvidened on
the average about live feet in the 4,000 years instead of
one foot ; and thus many valleys must have been tloepeued
and widened 100 feet, and some even more, since the
glacial epoch, while the more level portions of the country
will have been lowered on the average only about two feet.
174 ISLAND LIFE part i
Now Dr. Croll gives lis the following account of the
present aspect of the surface of a large part of the coun-
try :—
"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 Avill observe everywhere mounds and
hollows whicli cannot be accounted for by the j^resent
agencies at work. ... In regard to the general sur-
face 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
yet been made, that the kames, gravel-mounds, knolls -of
boulder clay, &c., still retain in most cases their original
form." ^
The facts here seem a little inconsistent, and we must
suppose that Dr. Croll has somewhat exaggerated the uni-
versality and complete iDreservation of the glaciated sur-
face. The amount of average denudation, however, is not
a matter of opinion but of measurement ; and its conse-
quences 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 has certainly been re-
modelled or carried into the sea since tlie last glacial epoch,
it becomes evident that any surface-phenomena produced
by still earlier glacial epochs must have long siiice entirely
disappeartuh
lUseuftlic Sca-lei'd Connected vntli Glacial Epochs, a Cause
of FuTtlicr Denudation. — 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 minor oscillations of the land,
without counting the great submergence of over 1,300 feet,
supposed to be indicated by patches of shelly clays and
gravels in Wales and Ireland, and also in a few localities in
England and Scotland, since these are otherwise explained
by many geologists. Other subsidences have no doubt oc-
curred iu the same areas during the Tertiary epoch, and
some writers connect these subsidences with the glacial
^ Climate and Time in their Geological llcUUions, p. 341.
CHAP. IX ANCIENT GLACIAL Kl'(j( IIS 17i
period itself, the unequal aiiiuunt of ice at the two poles
causing the centre of gravity of the earth to be ilisphiced
Avhen, of course, the surface of the ocean will coiif(.)rin to it
and appear to rise in the one heniisi)here and sink in the
other. If this is the case, subsidences of the land are
natural concomitants of a glacial period, and will power-
fully 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 culd persisted
through the successive phases of precession, and if so, both
polar areas would probably be glaciated at once. This
would cause the abstraction of a large quantity of water
from the ocean, and a proportionate elevation of the land,
Avhich would react on the accumulation of snow and ice,
and thus add another to that wonderful 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 an}'
important fluctuations of the sea-level is of comparatively
little importance to our present inquiry, because the wide
extent of marine Tertiary deposits in the northern hemi-
sphere and their occurrence at considerable elevations above
the present sea-level, afford the most conclusive proofs that
great changes of sea and land have occurred throughout
the entire Tertiary period ; and these repeated sub-
mergences and emergences of the land combined with
sub-aerial and marine denudation, would undoubtedly
destroy all those superficial evidences of ice-action on
which we mainly depend for i)roofs of the occurrence of the
last glacial epoch.
IV/iat Evidence of Earl y Glacial Eijoehs may he Expected. —
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
I'ractically indestructible.
One of the most constant of all (he })henoniena (tf a
glaciated country is the abundance of icebergs ]noduced by
the brcakinf^ off of the ends of <daciers which terminate
176 ISLAND LIFE takt i
in arms of the sea, or of the termmal face of the ice-sheet
which passes beyond the land into the ocean. In both
these cases abundance of rocks and cUhris, 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
imbedded stones, similar to that which forms the " till "
when deposited on land, will be carried out to sea witli the
ice and form a deposit of marine " till " near the shore.
It has indeed been objected that v.dien an ice-sheet
covered an entire country there would be no moraines, and
that rocks or cUhris are very rarely seen on icebergs.
But during every glacial epoch there will be a southern
limit to the glaciated area, and everywhere near this limit
the mountain-tops will rise far above the ice and deposit
on it great masses of debris ; and as the ice-sheet spreads,
and again as it passes away, this moraine-forming area
will successively occui3y the whole country. But even
such an ice-clad country as Greenland is now known to
have protruding peaks and rocky masses which give rise
to moraines on its surface ; ^ and, as rocks from Cumberland
and Ireland were carried by the ice-sheet 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 abundance of rock-laden bergs into
the surrounding seas ; and the same thing must have
occurred along all the coasts of Northern Europe and
Eastern America.
We cannot therefore doubt that throuo-hout the sTeater
part of the duration of a glacial epoch the seas adjacent to
the glaciated countries would receive continual deposits of
large rocks, rock-fragments, and gravel, similar to the
material of modern and ancient moraines, and analogous
to the drift and the numerous travelled blocks which the
ice has undoubtedly scattered broadcast over every glaciated
country ; and these rocks and boulders would be imbedded
in whatever deposits were then forming, either from the
matter carried down by rivers or from the mud ground off
^ JVatuir, Vol. XXL, p. 345, "The Interior of GreeiilaiKl."
I
ANCIENT GLACIAL EPOCHS 177
the rocks and carried out to sea by the ghiciers tlieiiiselves.
Moreover, as icebergs float far beyond the Hmits of the
countries which gave them birtli, these ice-borne materials
would be largely imbedded in deposits forming from the
denudation of countries which had never been glaciated, or
fi'om which the ice had already disapjieared.
But if every period of high excentricity produced a
glacial epoch of greater or less extent and severity, then,
on account of the frequent occurrence of a high phase of
excentricity during the three million years for which we
have the tables, these boulder and rock-strewn deposits
Avould be both numerous and extensive. Four hundred
thousand years ago the excentricity was almost exactly the
same as it is now, and it continually increased from that
time up to the glacial eiDOch. Now if we take double the
present excentricity as being sufficient to produce some
glaciation in the temperate zone, we find (by drawing out
the diagram at p. 171 on a larger scale) that during 1,150,000
years out of the 2,400,000 years immediately preceding
the last glacial epoch, the excentricity reached or exceeded
this amount, consisting of sixteen separate 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 three miUion years will
certainly include much, if not all, of the Tertiary period ;
and even if it does not, we have no reason to suppose that
the character of the excentricity would suddenly change
beyond the three million years.
It follows, therefore, that if periods of high excentricity,
like that which appears to have been synchronous with our
last glacial epoch and is generally admitted to have been
one of its efficient causes, always produced glacial epochs
(with or without alternating warm periods), then the whole
of the Tertiary deposits in the north temperate and Arctic
zones should exhibit frequent alternations of 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
N
178 ISLAND LIFE
theory of repeated glacial epochs during the Tertiary
period.
Evidences of Ice-action during tit c 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 glacial beds. The Miocene deposits of Central and
Southern Europe, for example, contain marine shells of
some genera now only found farther south, while the fossil
plants often resemble 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
twenty-six feet. Some of the blocks were observed by Sir
Charles Lyell to be faintly striated and partly polished on
one side, and they are scattered through the beds for a
thickness of nearly 150 feet. It is interesting that the
particular bed in which the blocks occur yields no organic
remains, though these are plentiful both in the underlying
and overlying beds, as if the cold of the icebergs, combined
with the turbidity produced by the glacial mud, 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 characteristically tropical
in its flora and fauna, since palms and Cycadaceae, turtles,
snakes, and crocodiles then inhabited England. Yet on
the north side of the Alps, extending from Switzerland to
Vienna, and also south of the Alps near Genoa, there is a
deposit of finely-stratified sandstone several thousand feet
in thickness, quite destitute of organic remains, but con-
taining in several places in Switzerland enormous blocks
either angular 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 105 feet long, ninety feet wide,
ANCIENT GLACIAL EPOCHS 179
and forty-live feet thick 1 Tlie granite is red, and of a
peculiar kind which cannot be matched anywhere in the
Alps, or indeed elsewhere. Similar erratics liave 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 sur-
rounding mountains, depositing these erratics, and cooling
the water so as to destroy the midlusca and other organisms
which had previously inhabited it. It is to be observed
that wherever these erratics occur they are always in the
vicinity of great mountain ranges ; and although these
can be proved to have been in great part elevated during
the Tertiary period, we must also remember that they
must have been since very much lowered by denudation, of
the amount of which, the enormously thick Eocene and
Miocene beds now forming portions of them is in some
degi'ee a measure as well as a proof. It is not theref(jre at
all improbable that during some part of the Tertiary period
these mountains may have been far higher than they
are now, and this we know might be sufficient for the pro-
duction of glaciers descending to the sea-level, even were
the climate of the lowlands somewhat warmer than at
present.^
The Weight of the Negative Evidence. — But when we
proceed to examine the Tertiary dej^osits of other parts of
^ Prof. J. AV. Judd says : "In tlie caso of the Alps I know of no glacial
phenomena which are not capable of being explained, like those of New
Zealand, by a great extension of the area of the tracts above the snow-line
which would collect more ample sui)plies for the glaciers protruded into
surrounding plains. And when we survey the grand panoramas of ridges,
pinnacles, and peaks produced for the most part b}^ sub-aerial action, we
may well be prepared to admit that before the intervening ravines and
valleys were excavated, the glaciers shed from the elevated plateaux must
have been of vastly greater magnitude than at present." (Contributions
to the Study of Volcanoes, Geological Magazine, 1876, p. 536.) Professor
Judd applies these remarks to the last as well as to previous glacial periods
in the Alps ; but surely there has been no such extensive alteration and
lowering of the surface of the country since the erratic 1 docks were de-
posited on the Jura and the great moraines formed in North Italy, as this
theory would imply. We can hardly sujii^ose wide areas to have been
lowered thousands of feet by denudation, and yet have left other adjacent
areas apparently untouched ; and it is even very doubtful whether su(di
an extension of the snow-fields would alone suffice for tlie effects whidi were
certainlv produced.
N 2
180 ISLAND LIFE
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 Con-
troversy " the late Mr. Searles Y. Wood, Jun., remarks on
this point as follows : " Now the Eocene formation is
complete in England, and is exposed in continuous section
along the north coast of the Isle of Wight from its base to
its junction with the Oligocene (or Lower Miocene ac-
cording to some), and along the northern coast of Kent
from its base to the Lower Bagshot Sand. It has been
intersected 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 collections 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, whether they
be the remains of a flora such as that of Sheppey, or of a
vertebrate fauna containing the crocodile and alligator,
such as is yielded by beds indicative of terrestrial condi-
tions, or of a molluscan assemblage such as is present in
marine or fluvio-marine beds of the formation, are of
unmistakably tropical or sub-tropical character through-
out ; and no trace whatever has appeared of the inter-
calation of a glacial period, much less of successive inter-
calations indicative of more than one period of 10,500
years' glaciation. Nor can it be urged that the glacial
epochs of the Eocene in England were intervals of dry
land, and so have left no evidence of their existence
behind them, because a large part of the continuous
sequence of Eocene deposits in this country consists of
alternations of fluviatile, fluvio-marine, and purely marine
strata ; so that it seems impossible that during the ac-
cumulation of the Eocene formation in Eno-land a oflaeial
period could have occurred Avithout its evidences being
CHAr. IX MILD ARCTIC CLIMATES 181
abundautly apparent. The Oligocene of Northern Ger-
many and Belgium, and the Miocene of tliose countries
and of France, have also afforded a rich moUuscan faun^i,
which, like that of the Eocene, has as yet presented no
indication of the intrusion of anything to interfere with its
uniformly sub-tropical character." ^
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 material, boulders or gravel, such
as Ave liave seen to be the essential characteristic of a glacial
epoch; and when we find that this same general character
pervades all the extensive Tertiary deposits of temperate
North America, we shall, I think, be forced to the con-
clusion that no general glacial epochs could have occurred
during their formation. It must be remembered that the
" imperfection of the geological record " will not liclp us
here, because the series of Tertiary deposits is unusually
complete, and we must suppose some destructive agency
to have selected all the intercalated glacial beds and to
have so completely made away with them that not a
fragment remains, while preserving all or almost all the
inter[jJaci(d beds ; and to have acted 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.
Tcm'prratc Climates in the Arctic Regions. — As we liave
just seen, the geological evidence of the persistence of sub-
tropical or warm climates in the north temperate zone
during tlie greater part of the Tertiary period is almost
irresistible, and we have now to consider the still more
extraordinary series of observations which demonstrate
that this amelioration of climate extended into tlie Arctic
zone, and into countries now almost wholly buried in snow
and ice. These warm Arctic cHmates have been explained
by Dr. Croll as due to periods of high excentricity with
winter in prrihrlion^ a tlieory which implies alternating
' (Jcolo(jlcal Jlar/azcnc, 1876, p. 392
182 ISLAND LIFE
epochs 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 mammoth, 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. How long ago 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 i° N. Lat. the trunk and root
of a fir tree which had evidently 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 four feet in circum-
ference and thirty feet long, were found by Lieut. Mecham in
Prince Patrick's Island in Lat. 76° 12' N., and other Arctic
explorers have found remains of trees in high latitudes.^
Similar indications of a recent milder climate are found
in Spitzbergen. Professor Nordenskjold says : " At various
places on Spitzbergen, at the bottom of Lomme Bay, at
Cape Thordsen, in Blomstrand's strata in Advent Bay,
there are found large and well-developed shells of a bivalve,
Mytilus edulis, which is not now found living on the coast
of Spitzbergen, though on the west coast of Scandinavia it
everywhere covers the rocks near the sea- shore. These
shells occur most j^lentifnlly in the bed of a river which
runs through Reindeer Valley at Cape Thordsen. They
1 Colonel Ficldeu thinks that these trees have all been brought clown
by rivers, and have been stranded on shores which have been recently
elevated. See Trans, of Norfolk Nat. Hist. Soc, Vol. III., 1880.
CHAP. IX MILD ARCTIC CLIMATES 183
are probably washed out of a thin bed of sand at a height
of about twenty or thirty feet above the present sea-level,
which is intersected by the river. The geological age of
this bed cannot be very great, and it has clearly been
formed since the present basin of the Ice Sound, or at
least the greater part of it, lias been hollowed out by
glacial action."^
Thr Miocene Arctic Flora. — One of the most startling
and important of the scientific discoveries of the last
forty years has been that of the relics of a luxuriant
Miocene flora in various parts of the Arctic regions. It is
a discovery that was totally unexpected, and is even now
considered by many men of science to be completely un-
intelligible ; but it is so thoroughly established, and it has
such a direct and important bearing on the subjects we are
discussing in the present volume, that it is necessary to
lay a tolerably complete outline of the facts before our
readers.
The Miocene flora of temperate Europe was very like
that of Eastern Asia, Japan, and the warmer part of East-
ern North America of the present day. It is very richly
represented in Switzerland by well preserved fossil remains,
and after a close comparison with the flora of other coun-
tries Professor Heer concludes that the Swiss Lower Mio-
cene flora indicates a climate corresjDonding to that of
Louisiana, North Africa, and South China, while the
Upper Miocene climate of the same country would corre-
spond to that of the south of Spain, Southern Japan, and
Georgia (U.S. of America). Of this latter flora, f(nind
chiefly at CB]ninghen in the northern extremity of Switzer-
land, 4()5 species are known, of which IGG species arc trees
or shrubs, half of them being evergreens. They comprise
sequoias like the Californian 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 Tc^ N. Lat.
we iiiid abundant remains of a flora of tlic same gcm^ral
^ Geological Magcainc, 1876, "(leolo^v of SpitzlxTgcii/' p. '2(^7.
184 ISLAND LIFE part i
type as that of CEninghen but of a more northern character.
We have a sequoia identical with one of the species found
at Q^ninghen, a chestnut, sahsburia, Hquidambar, sas-
safras, and even a niagnoha. We have also seven species
of oaks, two planes, two vines, three beeches, four poj^lars,
two willows, a walnut, a j^lum, and several shrubs supposed
to be evergreens; altogether 137 species, mostly well and
abundantly preserved !
But even further 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 including several of the Greenland species, and
others peculiar, but mostly of the same genera. There
seem to be no evergreens here except conifera?, one of
which is identical with the swamp-cyjoress {Taxodium
distichum) now found living in the Southern United States I
There are also eleven joines, two Libocedrus, two sequoias,
with oaks, poplars, birches, planes, limes, a. hazel, an asli,
and a walnut ; also water-lilies, pond-weeds, and an iris —
altogether about a hundred species of flowering plants.
Even in Grinnell Land, Avithin 8 J degrees of the pole, a
similar flora existed, twenty-five sjDecies of fossil plants
having been collected by the last Arctic expedition, of
which eighteen were identical with the species from other
Arctic localities. This flora comprised poplars, birches,
hazels, elms, viburnums, and eight species of conifers
including the swamp cypress and the Norway spruce
{Pinus ahics) which last does not now extend beyond
m° N.
Fossil plants closely resembling those just mentioned
have been found at many other Arctic localities, especially
in Iceland, on the Mackenzie River in Qo° N. Lat. and in
Alaska. As an intermediate station we have, in the neigh-
bourhood of Dantzic in Lat. 55° 'N., a similar flora, with
the swamp-cypress, sequoias, oaks, poplars, and some
cinnamons, laurels, and figs, A littLc further south, near
Breslau, north of the Carpathians, a rich flora has been
found allied to that of CEninghen, but wanting in some of the
more tropical forms. Again, in the Isle of Mull in Scotland,
in about 56?,^ N. Lat,, a plant-bed has been discovered con-
MILD ARCTIC CLIMATES 185
tiiining a hazel, a plane, and a sequoia, apparently identical
with a Swiss Miocene species.
We thus find one well-marked type of vegetation spread
from Switzerland and Vienna to North Germany, Scotland,
Iceland, Greenland, Alaska, and Spitzbergen, some few of
the species even ranging over the extremes of latitude
between G^ninghen and Spitzbergen, but the great ma-
jority being distinct, and exhibiting decided indications
of a decrease of temperature according to latitude, tliougli
much less in amount than now exists. Some writers liave
thought that the great similarity of the floras of Greenland
and(Eninghen is a proof that they were not contemporane-
ous, but successive ; and that of Greenland has been sup-
posed to be as old as the Eocene. But the arguments yet
adduced do not seem to prove such a difference of age,
because there is only that amount of specific and generic
diversity between the two which might be produced by dis-
tance and difference of temperature, 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 America, where many of the genera
and some of the species range from the Straits of Magellan
to Valparaiso — places differing as much in latitude as Swit-
zerland and West Greenland ; and the same may be said
of North Australia and Tasmania, where, at a greater lati-
tudinal distance apart, closely allied forms of Eucalyptus,
Acacia, Casuarina, Stylidium, Goodenia, and many other
genera would certainly form a in-oniinent feature in any
fossil flora now being preserved.
2I'ikl Ardir Climates of the Orctaccoas Period. — In the
U^Dper 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 geo-
logical age. Sixty-five species of plants liave been identi-
iied, of whicli there are fifteen ferns, two cycads, eleven
ooniferie, three monocotyledons, and thirty-four dicotyh^dons.
One of the ferns is a tree-fern witli thick stems, whicli lias
also been found in the Upper Grcensand of England.
Among the conifers the giant secpiuias arc fnind, and among
186 ISLAND LIFE tart i
the dicotyledons the genera Popukis, Myrica, Ficus, Sassa-
fras, Andromeda, Diospyros, Myrsine, Panax, as well as
magnolias, myrtles, and leguminosse. Several of these
grou23S occur also in the much richer deposits of the same
age in North America 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 absent from the other
merely because it has not yet been found there. On the
wliole, 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 Spitzbergen, 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 exogens, which
latter are 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 Glyptos-
trobus and Torreya now found only in China and Cali-
fornia, six species of true pines, and five of tlie genus
Sequoia, one of wliich occurs also in Spitzbergen. 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 exogens are
entirely absent, the above-named Greenland poplar being
the oldest known dicotyledonous plant.^
If we take these facts as really representing the flora of
the period, we shall be forced to conclude that, measured
by the change effected in its plants, the lapse of time be-
tween the Lower and Upper Cretaceous deposits was far
greater than between the Upj)er Cretaceous and the
Miocene — a conclusion quite opposed to the indications
afforded by the mollusca and the higher animals of the
two periods. It seems probable, tlierefore, that these
Lower Cretaceous plants represent local peculiarities of
^ Tlie procediiig account is mostly derived from rrofcssor Heer's great
work Flora Fossil is Arctica.
MILD ARCTIC CLIMATES 187
vegetation such as now sometimes occur in tro])ical
countries. On sandy or coralline islands in the Malay
Archii^elago there will often be found a vegetation con-
sisting almost wholly of cycads, pandani, and palms, while
a few miles otf, on moderately elevated land, not a single
specimen of either of these families may be seen, but a
dense forest of dicotyledonous trees covering the whole
country. A lowland vegetation, such as that above de-
scribed, might be destroyed and its remains preserved by a
slight depression, allowing it to be covered up by the (h>
tritus of some adjacent river, Avhile not only would tlu)
subsidence of high land be a less frequent occurrence, but
when it did occur the steep banks would be undermined
by the waves, and the trees falling down would be Heated
away, and would either be cast on some distant shore or
slowly decay on the surface or in the depths of the ocean.
From the remarkable series of foots now briefly sum-
marized, we learn, that whenever plant-remains have been
discovered within the Arctic regions, either in Tertiary
or Cretaceous deposits, they show that the climate was one
capable of supporting a rich vegetation of trees, shrubs,
and herbaceous plants, similar in general character to that
which prevailed in the temperate zone 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 scattered witliin the
Arctic circle, yet nowhere has any jiroof been obtained of
intercalated cokl periods, such as would be indicated by
the remains of a stunted vegetation, or a moUuscan fauna
similar to that which now prevails there.
Stratigrcqiliirrd Evidence of Long-Continued Jli/d Arctie
Conditions. — Letusnow turn to the stratigraphical evidence,
which, as we have 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 ])erhaiis tlie greatest living authority on Arctic geology
— Professor Nordenskjuld. In his lecture on " Tlie Former
Chmate of the Polar Pvcgions," he says: " Thr character
of the coasts in the Arctic regions is especially favourable
to geological investigations. While the valleys are for the
188 ISLAND LIFE pakt i
most part filled with ice, the sides of the mountains in
summer, even in the 80th degree of latitude, and to a height
of 1,000 or 1,500 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 everyAvhere exjDOse
their bare surfaces to the investigfator. The knowledo^e of
a mountain's geognostic 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
probability that strata of any considerable extent, contain-
ing boulders, are to be found in the polar tracts previous to
the middle of the Tertiary period. Since, then, both an
examination of the geognostic condition, and an investiga-
tion 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 jus-
tified 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
geological ages, enjoj^ed a magnificent climate, which
indeed was somewhat colder during the Miocene period,
but Avas still favourable for an extraordinarily abundant
vegetation, much more luxuriant than that which now
occurs even in the southern part of Scandinavia : and I
have in these strata sought in vain for any sign, that, as
some geologists have of late endeavoured to render probable,
these favourable climatic conditions have been broken off
^ Geological Magazine, 1875, p. 531.
MILD ARCTIC CLIMATES iS9
by intervals of ancient glacial periods. The jjiolilcs I have
had the opportunity to examine during my various Spitz-
bergen exi3editions would certainly, if laid down on a line,
occupy an extent of a thousand Enfflisli milrs ; and if any
former glacial period had existed in this region, there
ought to have been some trace to be observed of erratic
blocks, or otlier formations which distinguish 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, botli in
space and time, it is derived from the work of the most
competent living geologists, and it is absolutely consistent
in its general tendenc}^ 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 somewhat less
tropical ; but down to the Upper Miocene it remains warm
temperate in Central Europe, and cold temperate within
the polar 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 the record
between the Miocene and the recent glacial deposits.-
^ Geological Magazine, 1876, p. 266. In liis recent work — CUinatc ami
Cosmology (pp. 164, 172) — the late Dr. Croll lias appealed to the imperfection
of the geological record as a reply to these arguments ; in this i\ase, as it
appears to me, a very unsuccessful one.
* It is interesting to observe that the Cretaceous flora of the United
States (that of the Dakota group), indicates a somewhat cooler climate
than tliat of the following Eocene period. ]\Ir. De Ranee (in the geological
appendix to Capt. Sir G Nares's Narrative of a Voyage to the Polar Sea)
remarks as follows : " In the overlying American Eocenes occur types of
]tlants occurring in the European Miocenes and still living, proving the
truth of Professor Lesquereux's postulate, that the plant types appear in
America a stage in advance of iheir advent in Euroi)e. These plants
point to a far higher mean temperature than tliose of tlie Dakota group,
to a dense atmosphere of vapour, aiul a luxuriance of ferns and palms."
This is very important as adding furtlicr jiroof to tlie view that the
190 ISLAND LIFE
Accepting this as a substantially correct account of the
general climatic aspect of the Tertiary period in the
northern hemisphere, let us see 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," the late Dr. James
Croll has proved, with a wealth of argument and illustra-
tion Avhose cogency is irresistible, that the very habitability
of our globe is due 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 distribution of land and
sea ujDon the globe, more than its fair proportion of the
warm equatorial waters is directed towards the western
shores of Europe, the result being that the British Isles,
Norway, 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 benefit, 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 between Iceland and Britain by
which Avarm water penetrates within the Arctic circle, is
through Behring's Straits ; 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 North-west
America, while a very small quantity enters 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 backward would enter it, and would produce an
amelioration of the climate of which Ave can hardly form a
conception. A great amelioration of climate Avould also
be caused by the breaking up or the loAvering of such
climates of fonner periods are not due to any general refrigeration, but
to causes which were subject to change and alternation in former ages
as now.
CHAP. IX MILD ARCTIC CLIMATES 191
Arctic highlands as now favour the accnnmlatidn nf ice;
while the interpenetration of the sea into any p;irt (jf the
great continents in the tropical or temperate zones would
again tend to raise the winter temi^erature, and render any
long continuance of snow in their vicinity almost
impossible.
Now geologists have proved, quite independently of any
such questions as we are here discussing, that changes of
the very kinds above referred to have occurred during the
Tertiary period ; and that there has been, speaking broadly,
a steady change from a comparatively fragmentary and
insular condition of the great north temperate lands in
early Tertiary times, to that more compact and continental
condition which now prevails. It is, no doubt, difficult and
often impossible to determine how long any particular
geographical condition lasted, or whether the changes in
one country were exactly coincident with those in another ;
but it will be sufficient for our jDurpose briefly to indicate
those more important changes of land and sea during the
Tertiary period, which must have produced a decided
effect on the climate of the northern hemisphere.
Gcograpliical Changes Favouring Mild Northom Climates
ill Teriiarx] 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 Bliick and
Caspian Seas, and thence by narrower channels south-
eastward to the valley of the Euphrates and the Persian
Gulf, thus opening a communication between the North
Atlantic and the Indian Oceans. From the Caspian also a
wide arm of the sea extended during some part of the
Tertiary epoch northwards to the Arctic Ocean, and there
is nothing to show that this sea may not have been in
existence during the whole Tertiary ])eriod. Another
channel j^i'obably existed over Egypt ^ into the eastern
^ Mr. S, B. J. Skertehley informs me that lie lias liimself observed tliiek
Tertiary deposits, consisting of clays and anhydrous gy]isum, at Berenice
on the borders of Egypt and Nubia, at a height of about 600 feet above the
sea-level ; but these mav have been of fresh-water origin.
192 ISLAND LIFE
basin of the Mediterranean and tlie Black Sea ; while it is
probable that there was a communication between the
Baltic and the AVhite Sea, leaving Scandinavia as an
extensive island. Turning to India, Ave find that an arm
of the sea of great width and depth extended from the Bay
of Bengal to the mouths of the Indus ; while the enormous
depression indicated b}^ the presence of marine fossils of
Eocene age at a height of 16,500 feet in Western Tibet,
renders it not improbable that a more direct channel across
Afghanistan may have opened a communication between
the West Asiatic and Polar seas.
It ma}^ be said that the changes here indicated are not
warranted by an actual knowledge of continuous Tertiary
deposits over the situations of the alleged marine channels ;
but it is no less certain that the seas in which any partic-
ular strata Avere deposited Avere alicays more extensive
than the fragments of those strata noAv existing, and often
immensely more extensive. The Eocene deposits of
Europe, for example, have certainly undergone enormous
denudation both marine and subaerial, and may have once
covered areas Avhere Ave noAv find older deposits (as the
chalk once covered the weald), Avhile a portion of them
may lie concealed under Miocene, Pliocene, or recent beds.
We find them Avidely scattered over Eurojoe and Asia, and
often elevated into lofty mountain ranges ; and Ave should
certainly err far more seriously in confining the Eocene
seas to the exact areas Avhere Ave noAV find Eocene rocks,
than in liberally extending them, so as to connect the
several detached portions of the formation Avhenever there
is no A^alid 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 endeavour to estimate the j^robable
effect such communications Avould have upon the climate
of the northern hemisjDhere.
The Indian Ocean as a Source of Heat in Tertiary Tiraes.
— If AA^e compare the Indian Ocean Avith the South
Atlantic Ave shall see that the position and outline of the
former are very favourable for the accumulation of a large
body of Avarm Avater moving northAvards. Its southern
CHAP. IX MILD ARCTIC CLIMATES 193
opening between South Africa and Australia is very wide,
and the tendency of the trade- winds would be to concen-
trate the currents towards its north-western extremity,
just where the two great channels above described formed
an outlet to the northern seas. As will be shown in our
nineteenth chapter, there was probably, during the earlier
portion of the Tei'tiary 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 existence may have been favourable to tlie con-
veyance of heated water northward, by concentrating
the currents, and thus producing massive 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 probably
divided into two islands, separated by a wide channel in a
north and south direction (see Chapter XXIL), and
through this another current would almost certainly set
northwards, and be directed to the north-west by the
southern extension of Malayan Asia. The more insular
condition at this period of Australia, India, and North
Africa, with the depression and j)i'obable fertility of the
Central Asiatic plateau, would lead to the Indian Ocean
being traversed by regular trp de-winds instead of by
variable monsoons, and thus the constant vis a tergo,
which is so efficient in the Atlantic, would keep up a
steady and powerful current towards the northern parts
of the Indian Ocean, and thence through the midst of
the European archipelago to the northern seas.
Now it is quite certain that such a condition as we have
here sketched out would produce a wonderful effect on the
climate of Central Europe and Western and Northern Asia.
Owing to the warm currents being concentrated in iidand
seas instead of being dispersed over a wide ocean like thu
^ By rell'iriiirj to our map of the Indian Ocean sliowinff the submarinn
hanks indieatin<,' ancient ishands (Chap. XIX.), it will he evident that the
south-east trade-winds — then exceptionally powerful — would cause a vast
hody of water to enter the deep Arabian Sea.
O
194 ISLAND LIFE
North Atlantic, much more heat would be conveyed into
the Arctic Ocean, and this would altogether prevent the
formation of ice on the northern shores of Asia, which
continent did not then extend nearly so far north and was
probably deeply inter-penetr^ted by the sea. This open
ocean to the north, and the warm currents along all the
northern lands, would so equalise temperature, that even
the northern j^fii'ts 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 with-
out any help from similar changes in the western hemi-
sphere.^
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 sub-
sidence, and an insular condition of Western America with
a sea probably extending northwards to the Arctic Ocean.
As marine Tertiary deposits are found conformably over-
lying 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, Kamschatka, the Mackenzie Ri^er, the
Parry Islands, and Greenland, indicate partial submergence
1 In his recently published Lectures on Phijfiical Geography, Professor
Haughton calculates, that more than half the solar heat of the torrid zone
is carried to the temperate zones by ocean currents. The Gulf Stream itself
carries one-twelfth of the total amount, but it is probable that a A'ery small
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 corre-
sponding stream of the Indian Ocean in ]\[iocene times would have been
fully equal to the Gulf Stream in heating power, while, owing to its lieing
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.
CHAP. IX MILD ARCTIC CLIMATP:S 11.;
of all these lands with the possible influx of ^varni water
from the Pacitic ; and the considerable olevation of some
of the Miocene beds in Greenland and Siiitzbcrgen renders
it i^robable that these countries were then much less
elevated, in which case only their higher summits would
be covered with perpetual snow, and no glaciers would
descend to the sea.
In the Pacific there was probably an elevation of land
counterbalancing, to some extent, the great depression of
so much of the northern continents. Our map in Chapter
XV. shows the islands that would be jDroduced by an eleva-
tion of the great shoals under a thousand fathoms deep,
and it is seen that these all trend in a south-east and north-
west direction, and would thus facilitate tlie production of
definite currents impelled by the south-east trades towards
the north-west Pacific, where they would gain access to the
polar seas through Behring's Straits, which were, perhaps,
sometimes both wider and deeper than at present.
Effect of these Changes on the Climate of the Arctic Regions.
— These various changes of sea and land, all tending to-
wards a transference of heat from the equator to the north
temperate zone, were not improbably still further augmented
by the existence of a great inland South American sea
occupying what are now the extensive valleys of the
Amazon and Orinoco, and forming an additional reservoir
of super-heated vrater to add to the supply poured into the
North Atlantic.
It is not of course supposed that all the modifications
here indicated co-existed at the same time. We have good
reason to believe, from the known distribution of animals
in the Tertiary period, that land-communications liavc at
times existed between Europe or Asia and North America,
either by way of Behring's Straits, or by Iceland, Green-
land, and Labrador. But the same evidence shows that
these land-communications were the exception rather than
the rule, and that they occurred only at long intervals and
for short periods, so as at no time to bring about anything
like a com])lete interchange of the productions of tlie two
continents.^ We may therefore adniit that the communi-
^ For ail account of the resemblances and diUcienccs of the nianinialia
196 ISLAND LIFE
cation between the tropical and Arctic oceans was occasion-
ally interrupted in one or other direction ; but if we look
at a globe instead of a Mercator's chart of the world, we shall
see that the disi^roportion between the extent of the polar
and tropical seas is so enormous that a single wdde opening,
with an adequate impulse to carry in a considerable stream
of w^arm water, Avould be amply sufficient for the complete
abolition of polar snow and ice, when aided by the absence
of any great areas of high land within the polar circle, such
high land being, as w^e have seen, essential to the production
of perpetual snow even at the present time.
Those who wdsh to understand the effect of oceanic cur-
rents in conveying heat to the north temperate and polar
regions, should study the papers of Dr. Croll already re-
ferred 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 the mean annual tem-
l)eratures of the opposite coasts of Europe and America is
well known and has been already quoted, but the difference
of their mean vmitcr temi3erature is still more striking, and
it is this which concerns us as more especially affecting the
distribution of vegetable and animal life. Our mean
winter temperature in the w^est 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
further south ; and as Ave go northw^ard the difference in*
creases, 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 callable of
suj^porting most of the vegetable products of the American
coast in the latitude of Bordeaux.^
of tlic two continents during the Tertiary epoch, see my Geographical
Distribution of Aniiuals, A^oL I. pp. 140-15(3.
^ Professor Haughton has made an elaborate calcidation of tlie differ-
ence between existing climates and those of Miocene times, for all the
places where a IMiocene flora has been discovered, liy means of the actual
range of corresponding species and genera of plants. Although this
method is open to the objection that the ranges of plants and animals arc
not determined by temperature only, yet the results may be approxi-
mately correct, and are very interesting. The following table which
CHAP. IX
MILD ARCTIC CLLMATES
With these astoundmg facts before us, dnv wliollv to the
transference of a portion of tlie warm curn.'nts' of the
Atlantic to the shores of Europe, e\ei\ witli all the disad-
\'antages of an icy sea to the north-east and ice-covered
Greenland t(j the north-west, how can we doubt the enor-
mously greater effect of such a condition of things as has
been shown to have existed during the Tertiary epoch {
Instead of one great stream of warm water spreading widelv
over the North Atlantic and thus losing tlie greater part
of its store of heat before it reaches the Arctic seas, we
should have several streams conveying the heat of far more
extensive tropical oceans by comparatively narrow inland
channels, thus being able to transfer a large proportion of
their heat into the northern 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
atmosijhere, would directly ameliorate the climate of the
continents they passed through, and prevent all accumu-
lation of snow except on the loftiest mountains. The
formation of ice in the Arctic seas would then be impos-
sible ; and the mild winter climate of the latitude of North
summarizes these results is taken from his Lectures on PIn/sirn? Gcoamphu
(p. 344):- ^ ' '^
Latitude.
Present
Tcmperaturp.
Temperalure. difference.
1 j
1. SwitzerlaiKl . .
2. 13antzig . . .
3. Iceland . . .
4. Mackenzie River
5. Disco (GreeiilniKl
6. Spitzbergen . .
7. Grinnell Land .
47°.00
54°. 21
65°. 30
65°. 00
70°.00
78°.00
81°. 44
53°. 6 F.
45°. 7 .,
35°. 6 „
19°.4 .,
19°.6 ,,
i6°.5 ;,
1°.7 „
69°. 8 F.
62°. 6 ..
48°. 2 .,
48°.2 .,
55°. 6 .,
51°. 8 ..
42°. 3 .,
16'. 2 F.
16^9 ..
12°.6 .,
28°. 8 ..
36°.0 „
35°. 3 .,
44°. 0 „
It is interesting to note that Iceland, whirli is now exposed to the lull
influence of the Gulf Stream, was only 12^-6 F. warmer in .Miocene times,
while ihackenzio River, now totally removed from its influence was
28° warmer. This, as well as the givater increase of temperature as we
go northward and the polar area becomes more limited, is (juite in accord-
ance with the view of the causes which brought about the Miocene climate
which is here advocated.
198 ISLAND LIFE
Carolina, Avliich by the Gulf Stream is transferred 20"
northwards to our islands, might certainly, under the
favourable conditions which prevailed during the Creta-
ceous, Eocene, and Miocene periods, have been carried
another 20"" north to Greenland 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 ice-accumu-
lation prevented, the high northern lands would be able to
support a far more luxuriant summer vegetation than is
possible in our unequal and cloudy climate.^
Effect of High Exccntrkity on the Warm Polar Climates. —
If the explanation of the cause of the glacial epoch given
in the last chapter is a correct one, it will, I believe, follow
that changes in the amount of excentricity will produce n( ►
important alteration of the climates of the temperate and
Arctic zones so long as favourable geographical conditions,
such as have been now sketched out, render the accumu-
lation of ice impossible. The effect of a high excentricity
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 inter-
position of a protective covering of cloud and vapour.
But mobile currents of water have no such power of
^ The objection has been made, that the long pohir night would of itself
be fatal to the existence of such a luxuriant vegetation as we know to liave
existed as far as 80° X. Lat., and that there must have been some altera-
tion 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 appears to be really no valid grounds for such an
objection. Xot only are numbei s 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 tlius exposed to as much darkness as the night of the
Arctic regions. AVe have besides no proof that any of the Amtic trees or
large shrubs were evergreens, and the darkness would certainly not be
prejudical to deciduous plants. With a suitable tem[»LTiture there is
nothing to prevent a luxuriant vegetation up to the pole, and the long con-
tinued day is known to be highly favourable to the development of foliage,
which in the same species is larger and better developed in Norway than in
the south of England.
MILD ARCTIC CLIMATES 199
accumulating and storing up heat or cold from one year to
another, though they do in a pre-eminent degree possess
the power of equalising the temperature of winter and
summer and of conveying the superabundant heat of the
tropics to ameliorate the rigour of the Arctic winters.
However great was the difference between tlie amount of
heat received from the sun in winter and summer in the
Arctic zone during a period of high excentricity and
winter in aphelion, the inequality w^ould be greatly dim-
inished by the free ingress of warm currents to the polar
area; and if this was sufficient to prevent any accumu-
lation of ice, the summers would be warmed to the full
extent of the powers of the sun during the long polar day,
which is such as to give the pole at midsummer actually
more heat during the tw^enty-four hours than the equator
receives during its day of twelve hours. The only
difference, then, that would be directly produced by the
changes of excentricity and precession would be, that the
summers w^ould be at one period almost tropical, at the
other of a more mild and uniform temperate character;
while the winters would be at one time somewhat longer
and colder, but never, probably, more severe than they are
now in the w^est of Scotland.
But though high excentricity would not directly modify
the mild chmates produced by the state of the northern
hemisphere which prevailed during Cretaceous, Eocene,
and Miocene times, it might indirectly affect it by in-
creasing the mass of Antarctic ice, and thus increasing the
force of the trade-winds and the resulting northward-
flowing warm currents. Now there are many peculiarities
in the distribution of plants and of some groups of- animals
in the southern hemisphere, which render it almost certain
that there has sometimes been a greater extension of the
Antarctic 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 hemi-
sphere, due to the peculiar distribution of land and sea
which favours the production of ice-fields and glaciers.
And as w^e have seen that during the last three million years
the excentricity has been almost alwavs much higher than
200 ISLAND LIFE
it is now, we should expect that the quantity of ice in the
southern hemisphere will usually have been greater, and
wdll thus have tended to increase the force of those oceanic
currents which jDroduce the mild climates of the northern
hemisphere.
Evidences of Climate in the Secjndary and Pcdmozoic
Epochs. — We have already seen, that so far back as the
Cretaceous period there is the most conclusive evidence of
the prevalence of a very mild climate not only in temperate
but also in Arctic lands, while there is no proof whatever,
or even any clear indication, of early glacial epochs at all com-
parable in extent and severity with that which has so
recently occurred ; and we have seen reason to connect this
state of things with a distribution of land and sea highly
favourable to the transference 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 further 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, in the Brittish area, become p)Oorer, 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 some
indications of ice-action are found in the Lower Permian
conglomerates of the west of England. These beds contain
abimdant fragments of various rocks, often angular and
sometimes weighing half a ton, while others are partially
rounded, and have polished 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 explanation
that, with our present knowledge, we can give of them.
Permian breccias are also found in Ireland, containing
CHAP. IX GEOLOGICAL CLLMATES 201
blocks of Silurian and Old Red sandstone rocks wliicli
Professor Hull believes could oidy have been carried bv
floating ice. Similar breccias occur in the south of Scotland,
and these are stated to be " overlain by a deposit of glacial
age, so similar to tlie breccia below as to be with ditficultv
distinguished from it." ^
These numerous physical indications of iee-actiun (jver
a considerable area during the same geological period,
coinciding with just such a poverty of organic remains as
might be produced by a very culd climate, are very import-
ant, and seem clearly to indicate that at this remote
period geographical conditions were such as to bring about
a glacial epoch, or perhaps only local glaciation, in our ])art
of the world.
Boulder-beds also occur in the Carboniferous formation,
both in Scotland, on the continent of Europe, and in North
America ; and Professor Dawson considers that he has
detected true glacial deposits of the same age in Nova
Scotia. Boulder-beds also occur in the Silurian rocks of
Scotland and North America, and according to Professor
Dawson, even in the Huronian, older than our Cambrian.
None of these indications are how^ever so satisfactory as
those of Permian age, wdiere we have the very kind of
evidence we looked for in vain throughout the wliole of
the Tertiary and Secondary periods. Its presence in
several localities in such ancient rocks as the Permian is
not only most important as indicating a glacial epoch of
some kind in Palaeozoic times, but confirms us in the validity
of our conclusion, that the total absence of any such evidence
throughout the Tertiary and Secondary epochs demon-
strates the absence of recurring glacial epochs in the
northern hemisphere, notwithstanding the freipient recur-
rence of periods of high excentricity.
Warm Arctic Climates in Early Secondary and Fahrozoic
Times. — The evidence w^e have already adduced of the mild
climates prevailing in the Arctic regions throughout the
Pliocene, Eocene, and Cretaceous periods is supplemented
by a considerable body of facts relating to still earlier
epochs.
^ Geoloyical Mividunc, Ibl'o, p. 32U.
202 ISLAND LIFE pabtI
In the Jurassic period, for exam])le, we have proofs of a
mild Arctic cHmate, in the abundant plant -remains of
East Siberia and Amurland, with less productive deposits
in Spitzbergen, and at Ando in Norway just within the
Arctic circle. But even more remarkable are the marine
remains found in many places in high northern latitudes,
nmong which we may especially mention the numerous
ammonites and the vertebrse of huge reptiles of the
oenera Ichthyosaurus and Teleosaurus found in the
Jurassic deposits of the Parry Islands in 77° N. Lat.
In the still earlier Triassic age, nautili and ammonites
inhabited the seas of Spitzbergen, where their fossil re-
mains are now found.
In the Carboniferous formation we again meet with
plant-remains and beds of true coal in the Arctic regions.
Lepidodendrons and Calamites, together with large spread-
ing ferns, are found at Spitzbergen, and at Bear Island in
the extreme north of Eastern Siberia ; while marine
deposits of the same age contain abundance of large stony
corals.
Lastly, the ancient Silurian limestones, which are
Avidely spread in the high Arctic regions, contain abund-
ance of corals and cephalopodous mollusca resembling
those from the same deposits in more temperate lands.
Conclusions 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 character. Whether in Miocene,
Upper or Lower Cretaceous, Jurassic, Triassic, Carbonif-
erous or Silurian times, and in all the numerous localities
extending over more than half the polar regions, 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 excentricity, and persistent
cold epochs when the excentricity was as low^ as it is now
or lower, for that would imply that the duration of cold
conditions was grecder than that of warm. Why then
should the fauna and flora of the cold epochs never be
(lEOLOGICAL C'Ll.MA'rKS 'JO.'J
preserved ? Mollusca and many other iurnis *»f life art-
abundant in the Arctic seas, and tliere is often a hixuriant
dwarf woody vegetation on the hind, yet in no one cas<j has
a single example of such a fauna or flora been discovered
of a date anterior to the last glacial epoch. And this
argument is very much strengthened when we remembei-
that an exactly analogous series of facts is found over all
the temperate zones. Everywhere we have abundant
floras and faunas indicating warmer conditions than such
as now prevail, but never in a single instance one which
as clearly indicates colder conditions. The fact that drift
with Arctic shells was deposited during the last glacial
epoch, as well as gravels and crag with the remains of
arctic animals and j^lants, shows us that tliere is nothing
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 destroyed, while in a considerable number of
instances those of the latter have been preserved. When
to this uniform testimony of the palieontological evidence
we add the equally uniform absence of any indication of
those ice-borne rocks, boulders, and drift, which are the
constant and necessary accompaniment of every period of
glaciation, and which must inevitably pervade all the
marine deposits formed over a wide area so long as the
state of glaciation continues, we are driven to the conclu-
sion that the last glacial epoch of the northern hemisphere
was exceptional, and w^as not preceded by numerous
similar glacial epochs throughout Tertiary and Second-
ary time.
But although glacial epochs (with the one or two excep-
tions already referred to) were certainly absent, consider-
able changes of climate may have frequently occurred, and
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 in general character. We have also the testi-
mony of Mr. J. 8. Gardner, who has long worked at the
fossil floras of the Tertiary deposits, and who states, that
204 ISLAND LIFE
there is strong negative and some positive evidence of
alternatinp- warmer and colder conditions, not crlaciaL
contained not only in English Eocene, but all Tertiary
beds throughout the world.^ In the case of marine faunas
it is more difficult to judge, but the numerous changes in
the fossil remains from bed to bed only a few feet and
sometimes a few inches apart, may be sometimes due to
change of climate ; and when it is recognised that such
changes have i^robably occurred at all geological epochs
and tlieir effects are systematically searched for, many
peculiarities in the distribution of organisms through
the different members of one deposit may be traced to
this cause.
General View of Geological Climates as dependent on the
Fhysieal Features of the Earth's Surface. — In the pre-
ceding chapters I have earnestly endeavoured 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 eluci-
dation. If my conclusions as here set forth diverge consid-
erably from those of Dr. CroU, it is not 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 whole
question has now convinced me that an error has been
made in estimating the comparative effect of geographical
and astronomical causes on changes of climate, and that,
while the latter have undoubtedly played an important
part 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. Croll'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
Distribution of Heat over the Globe." The main features
of this theory as distinct from that of Dr. CroU I will now
endeavour to summarise.
Looking at the subject broadly, we see that the climatic
^ Geological Marjazine, 1877, p. 137.
CHAP. IX GEOLOGICAL CLIMATES 205
condition of tlie northern hemisi)hure is the result of the
pecuUar distribution of land and water upon the globe ;
and the general permanence of tlie position of the con-
tinental and oceanic areas — which we have shown to be
proved l)y so many distinct lines of evidence — is also im-
plied by the general stability of climate througliout 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 termi-
nating in three comparatively narrow extremities re-
presented by Southern America, South Africa, and Aus-
tralia. Towards the north these masses have approached
each other, and have sometimes become united ; leavincr
beyond them a considerable area of open polar sea.
Towards the south they have never been much further
prolonged than at present, but far beyond their extremities
an extensive mass of land has occupied the south jiolar
area.
This arrangement is such as W(juld cause the northern
lieinisphere 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 w^ould bring
about the concentration of the latter in three great streams
carrying warmth to tlie north-polar regions. These streams
would, as ])r. Croll has so well shown, be greatly increased
in power by the giaciation of the south polar land ; and
whenever any considerable portion of this land w^as ele-
vated, such a condition of giaciation would certainly be
brought about, and w^ould be heightened whenever a high
degree of excentricity prevailed.
It is now tlie general opinion of geologists tliat thr
great continents liave undergone a process of development
from earlier to later times. Professor Dana appears to
have been the first who taught it explicitly in the case of
the North American continent, and he has continued the
development of his views from 1850, when he discussed
the subject in the American Joitrnal, to the later editions
of his Manual of GfjAofiy in which tlie same views are ex-
tended to all the great conxinents. He says : —
"The North American continent, which since earlv
206 ISLAND LIFE
time had been gTaclually expanding in each direction from
the northern Azoic, eastward, westward, and southward,
and which, after the Palaeozoic, Avas finished in its rocky
foundation, excepting on the borders of the Atlantic and
Pacific and the area of the Rocky Mountains, had reached
its full expansion at the close of the Tertiary period. The
progress from the first was uniform and systematic : the
land was at all times simple in outline ; and its enlarge-
ment took place with almost the regularity of an ex-
ogenous plant."^
A similar development undoubtedly took place in the
European area, which was apparently never so compact and
so little interpenetrated by the sea as it is now, while
Europe and Asia have only become united into one un-
broken mass since late Tertiary times.
If, however, the greater continents have become more
compact and massive from age to age, and have received
their 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 exj^lain the persistence, with slight fiuctua-
tions, of warm climates far into the north-polar area
throughout Palseozoic, Mesozoic, and Tertiary times. At
length, during the latter part of the Tertiary epoch, a con-
siderable 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 snow and
ice-fields. This elevation is indicated by the abundance of
Miocene and the absence of Pliocene deposits in the Arctic
zone and the considerable altitude of many Miocene rocks
in Europe and North America ; and the occurrence at this
time of a long-continued period of high excentricity
necessarily brought on the glacial epoch in the manner
already described in our last chapter. A depression seems
to have occurred during the glacial period itself in North
America as in Britain, but this may have been due partly
to the weight of the ice and partly to a rise of the ocean
' Manual of Gcohyv, 2nd Ed. p. 525^ See also letter in Nature, Vol.
XXIII. p. 410.
GEOLOGICAL CLLMATE8 207
level caused by the earth's centre of gravity being sliifted
towards the north.
We thus see that the last glacial epoch was the climax
of a great process of continental development which had
been going on throughout long geological ages ; and that it
was the direct consequence of the north temperate and
polar land having attained a great extension and a con-
siderable altitude just at the time when a phase of very
high excentricity was coming on. Througliout earlier
Tertiary and Secondary times an equally high excentricity
often occun-ed, but it never produced a glacial epocli, be-
cause the north temperate and polar areas had less liigh
land, and were more freely open to the influx of warm
oceanic currents. But wherever great plateaux with lofty
mountains occurred in the temperate zone a considerable
local giaciation might be produced, which would be
specially intense during periods of high excentricity ; and
it is to such causes we must impute the indications of ice-
action in the vicinity of the Alps during the Tertiary
period. The Permian giaciation 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 northwards towards the pole, to have brought on a
true glacial period comparable with that which has so
recently passed away.
Estimate of the comparatice effects of Gcograpliical and
Astronomical Causes in livcclucing 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 prevailed in the Arctic regions, the con-
currence of astronomical causes — high excentricity with
winter in aphclloit — was necessary 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 events — were simultaneously elevated so as to bring
extensive areas above the line of perpetual snow ; that
208 ISLAXD LIFE
about the same time Scandinavia, the Alps, and the
Pyrenees received a similar increase of altitude ; and that,
almost simultaneous!}', Eastern North America, the Sierra
Nevada of California, the Caucasus, Lebanon, the southern
mountains of Spain, the Atlas range, and the Himalayas,
were each some thousands of feet higher than they are
now ; for all these mountains present us with indications
of a recent extension of their glaciers, in superficial phe-
nomena so similar to those which occur in our own country
and in Western Europe, that we cannot suppose them to
belong to a different epoch. Such 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 islands could have brought about
the extreme amount of glaciation which they certainly
underwent, and when, further, we know that a phase of
very high excentricity did occur at a period which is
generally admitted to agree well with physical evidence of
the time elapsed since the cold 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
necessarily to frequently recurring glacial epochs tlirough-
out all geological time. But I have here endeavoured to
show that this is not a necessary consequence of the theory,
because a concurrence of favourable geographical con-
ditions is essential to the initiation 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 excentricity. AVhen, however,
geographical conditions favour warm Arctic climates — as
it has been shown they have done throughout the larger
portion of geological time — then changes of excentricity, to
however great an extent, have no tendency to bring about
a state of glaciation, because warm oceanic currents have a
• HAi'. IX GEOLOGICAL CLIMATES 209
preponderating influence, and without very larfo areas of
liigh 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 u,
geologists, since it shows the direct dependence of climate
on physical processes, which are guided and modified by
those changes in the earth's surface wdiich geology alone
can trace out. It is in perfect 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 inportant departure from the great lines of
elevation and depression originally marked out on the
earth's surface has ever taken place.
It also shows us how important an agent in the jjro-
duction of a habitable globe with comparatively small
extremes of climates over its whole area, is the great dis-
proportion between the extent of the land and the water
surfaces. For if these proportions 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 easiU'
have led to half the land surface becoming covered with
perpetual snow and ice, or being exposed to extremes of
sunmier heat and winter cold, of which our w^ater-
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 thr
singular arrangement of the land in three great southward-
pointing masses — are really facts of the greatest signific-
ance and importance, since it is to these very anomalies
that the universal spread of vegetation and the adapt-
ability of so large a portion of the earth's surfnce f^r
linman habitation is directly due.
CHAPTER X
THE earth's age, AND THE EATE OF I)EVELOP>[ENT OF
ANIMALS AND PLANTS
Various Estimates of Geological Time — Denudation ami Deposition of
Strata as a ]\Ieasure of Time — How to Estimate the Tliickness of the
Seclimentar}' Rocks— How to Estimate the Average Rate 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 ]\Iodification Dependent on Change of Conditions —
Geographical Mutations as a ]\Iotive 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.
The subjects discussed in the last three chapters intro-
duce us to a difficulty which has hitherto been considered
a very formidable one — that the maximum age of the
habitable earth, as deduced from physical considerations,
does not afford sufficient time either for the geological or
the ororanic chano-es of which we have evidence. Geolo-
gists continually dwell on the slowness of the processes of
upheaval and subsidence, of denudation of the earth's sur-
face, and of the formation of new strata ; while on the
theory of development, as exj30unded by Mr. Darwin, the
variation and modification of organic forms is also a very
slow process, and has usually been considered to require an
CHAP. X THE EARTH'S AGE 211
even lousier series of iii^es than might satisfy the require-
^^ — ^^.*^„ „- „j^.
nients of physical geology alone.
As an indication of the periods usually contemplated by
geologists, we may refer to Sir Charles Lyell's calculation
in the tenth edition of his Principles of Geology (omitted
in later editions), by which he arrived at 240 millions of
years as having probably elapsed since the Cambrian jjcriod
— a very moderate estimate in the opinion of most geolo-
gists. This calculation was founded on the rate of modi-
fication of the species of mollusca; but much more recently
Professor Haughton has arrived at nearly similar figures
from a consideration of the rate of formation of rocks and
their known maximum thickness, whence he deduces a
maximum of 200 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 formation of tlic
known stratified rocks only represents a portion, and per-
haps a small portion, of geological time. In the sixth edition
of the Origin of Species (p. 286), Mr. Darwin says : " Con-
sequently, 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 age to the present day ;
and that daring these vast periods the world swarmed with
living creatures." Professor Huxley, in his anniversary
address to the Geological Society in 1870, adduced a num-
ber of special cases showing that, on the theory of develop-
ment, almost all the higher forms of life must have existed
during the PalaH")zoic period. Thus, from the fact that almost
the Avhole of the Tertiary period has been required to convert
the ancestral Orohippus into the true horse, he 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), we should require a
large portion, if not the whole, of the Mesozoic or Second-
ary period. Another case is furnished by the bats and
whales, both of which strange modifications of the mam-
^ .Ya/^//v. Vol. XVIir. (.Tulv. 187SV ].. 2»?s.
212 ISLAND LIFE i-aht i
malian type occur perfectly developed in the Eocene for-
mation. 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
period ; 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 : " If the very 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 almost appalling to
reflect how far back in Pala?ozoic times we must go before
we can hope to arrive at that common stock from which
the crocodiles, lizards, Ornithoscelida, and Plcsiosauria ,
wdiich had attained so great a development in the Triassic
epoch, must have been derived." Professor Ramsay has
expressed similar views, derived from a general study of
the Avhole series of o-eoloo^ical formations and their con-
tained fossils. He says, speaking of the abundant, varied,
and well-developed fauna of the Cambrian period : " In
this earliest known I'aricd life we find no evidence of its
havins^ lived near the beo^innino- of the zoolo^'ical series.
In a broad sense, comjDared with what must have gone
before, both biologically and j^hysically, all the phenomena
connected with this old period seem, to my mind, to be of
quite a recent descrijotion ; 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 200
millions of years, the date of the commencement of life on
the earth cannot be much less than 500 millions ; while it
may not improbably have been longer, because the reaction of
^ " On the Comparative Value of certain Geological Ages considered as >
items of Oeological Time." [Proceedings of the Roval Soeirfv 1874, p.
334.1 ' ' - '
CMAP. X THE EARTH'S AGE liia
the organism under changes of the environment is believed
to have been less active in low and simple, than in high
and complex forms of life, and thus the processes of organic
development may for countless ages have been excessively
slow.
But according to the physicists, no sucli periods as arc
here contemplated can be granted. From a consideration
of the possible 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 in-
crease of temperature as we descend beneath the surface,
Sir William Thomson concludes that the crust of the
earth cannot have been solidified much longer than 100
million years (the maximum possible being 400 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 geological
time, may affect the rate of biological change.
Denudation and Dci^osition 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 exposed to the destructive influences of
sun and wind, frost, snow, and rain, which break up and
Avear away the hardest rocks as well as the softer deposits,
and by means of rivers 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
dJbris at the foot of every inland cliff; of enormous deposits
of gravel, sand, and loam ; as well as the shingle, pebbles,
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
discoloured after each heavy rainfall, since the matter which
causes this discolouration must be derived from the surface
^ Trans. Royal Society of Edinhnrgh, Vol. XXIII. \\ 1^1- Quarterly
Jourval of Science, 1877. (Croll on the ''Prob;iblo Origin and Age of the
.Sun.")
214 ISLAND LIFE part i
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 universality of this
subaerial denudation, both as regards space and time,
renders it certain that its cumulative effects must be very
great ; but no attempt seems to have been made to deter-
mine 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 accuracy), we may obtain the amount of
lowering of the land-area, and also the rise of the ocean
level, owing to the quantity of matter deposited on its
floor. A few years later Dr. Croll apj^lied the same 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 Sir A. Geikie, Sir Charles Lyell,
and all our best geologists, as affording a means of actually
determining with some approach to accuracy, the time
occupied by one important phase of geological change.
The quantity of matter carried away from the land by a
river is gi'eater than at first sight appears, and is more
likely to be under- than over-estimated. By taking
samples of water near the mouth of a river (but above the
influence of the tide) at a sufticient 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 sohd matter held in
suspension and solution ; and if corresponding obser\'ations
determine the quantity of water that is discharged, the
total amount of solid matter brought down annually ma}'
be calculated. But besides this, a considerable quantity
of sand or even gravel is carried along the bottom or bed
of the river, and this has rarely been estimated, so that
the figures hitherto obtained are usually 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 lands during its course, for this adds to the
amount of denudation performed by the river, although
^ riiihsoiiliiralMafja'.inc, April, 1853.
CHAP. X THE EARTH'S AGE 216
the matter so deposited does not come down to the sea.
After a careful examination of all the best records,
Sir 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 ]\Iississippi removes one loot in 6,000 years.
,, Ganges ,, ,, 2,358 ,,
,, Hoang Ho ., ,, 1,464 ,,
., Rhone ,, '., 1,528 ,,
,, Danube ., ., 6,846 .,
., Po ., ., 729 ,,
., Nith .. .. 4,723 .,
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 j^lateaux
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
being then what we might expect, and as all arc probabl}^
under rather than over the truth, we may safely take the
average of them all as representing an amount of denuda-
tion which, if not true for the whole land surftice of the
globe, will certainly be so for a very considerable propor-
tion of it. This average is almost exactly one foot in
three thousand years.^ The mean altitude of the several
^ It has usually been the practice to take the amount of denudation in
the Mississippi valley, or one foot in six thousand years, as a measure of tlie
rate of denudation in Europe, IVom an idea apparently of being on the
"safe side," and of not over-estimating the rate of change. But tliis
appears to me a most un])lulosophical mode of proceeding and unworthy
of scientific inquiry. AVhat should we think of astronomers if tliey always
took the lowest estimates of planetary or stellar distances, instead of the
mean results of observation, " in order to be on the safe side!"? As if
error in one direction weie any worse than error in another. Yet this is
what geologists do systematically. Whenever any calculations are made
involving the antiquity of man, it is those that give the loicsf results that
are always taken, for no reason apparently except that there was. for so long
a time, a prejudice, both popular and scientific, against the great antiquity
'>f man ; an<l now tliat a means has been found of measuring the rate of
216 ISLAND LIFE
continents has been recently estimated by Mr. John
Murray,^ to be as follows : Europe 939 feet, Asia 3,189
feet, Africa 2020 feet. North America 1,888 feet, and South
America 2,078 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 eight
hundred thousand years ; while if we take a somewdiat
slower rate for North America, that continent might last
about four or five million years.- This also implies that
the mean height of these continents would have been
about double what it is now three million and five million
years ago respectively : and as we have no reason to
suppose this to have been the case, we are led to infer
the constant action of that upheaving force which the
presence of sedimentary formations even on the highest
mountains also demonstrates.
We have already discussed the unequal rate of denuda-
tion on hills, valleys, and lowlands, in connection with the
evidence of remote glacial epochs (p. 173) ; what we have
now to consider is, what becomes of all this denuded
matter, and how far the known rate of denudation affords
us a measure of the rate of deposition, and thus gives us
some indication of the lapse of geological time from a
comparison of this rate with the. observed tliickness of
stratified rocks on the earth's surface.
denudation, they take the slowest rate instead of the mean rate, apparently
only because there is now a scientific prejudice in favour of extremely slow
geological change. I take the mean of the whole ; and as this is almost
exactly the same as the mean of the three great European rivers — the
Rhone, Danube, and Po — I cannot believe that this Avill not be nearer the
truth for Europe than taking one North American river as the standard.
^ " On the Height of the Land and the Depth of tlie Ocean," in the
Scottish Geographical Magazine, 1888.
- These figures are merely used to give an idea of the I'ate at which de-
nudation is actually going on now ; but if no elevatory forces were at
work, the rate of denudation would certainly diminish as the mountains
were lowered and the slope of the gi-ound everywhere rendered Hatter.
This would follow not only from the diminished power of rain and rivers,
but because the climate would become more uniform, the rainfall probably
less, and no rocky peaks would be left to be fractured and broken up by
the action of frosts. It is certain, however, that no continent has ever
i-^mained long subject to the influences of denudation alone, for, as we
have seen in our sixth chapter, elevation and depression have always been
going on in one part or other of the surface.
C1IA1-. X THE EARTH'S AGE
Hoiv to Estimate the Thkhicss of the Sedimentary Jioeks.
— The sedimentary rocks of which the earth's crust is
mainly composed consist, according to Sir Charles Lyell's
classification, of fourteen great formations, of which the
most ancient is the Laurentian, and the most recent the
Post-Tertiary or Pleistocene; with thirty important sub-
divisions, each of which again consists of a more or less
considerable number of distinct beds or strata. Thus, the
Silurian formation is divided into Uj:>per and Lower
Silurian, each characterized by a distinct set of f<jssil
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 Lland(j\ery
Slates, &c., each usually characterised by a difference of min-
eral composition or mechanical structure, as well as by some
peculiar fossils. These beds and formations vary greatly in
extent, both above and beneath the surface, and are also of
very various thicknesses in different localities. A tliick 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 c<jntact.
As an example of this thinning out, American geologists
adduce tlie Palaeozoic formations of the Appalachian Moun-
tains, which have a total thickness of 42,00U feet, but as
they are traced westward thin out till they become only
4,000 feet in total thickness. In like manner the Carboni-
ferous grits and shales are 18,000 feet thick in Yorksliirc
and Lancashire, but they thin out southwards, so tliat in
Leicestershire they are only 3,000 feet thick ; and similar
phenomena occur in all strata and in every part of the
world. It must be observed that this thinning out has
nothing, to do with denudation (which acts u])on 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 deticiency of sediment in certain directions at the
original formation of the deposit. Cwing to this thinning
out of stratified rocks, they are on the whole of fcir less
extent than is usually supposed. Wlien we see a geologi-
cal map showing successive formations following each
other in lonij' irreuular belts across the countrv (ns is well
218 ISLAND LIFE ?akt i
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 should 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 Gault Clay,
which latter immediately rests on the Upper Silurian
Wenlock Limestone full of characteristic fossils, at a depth
of only 800 feet. Here we have an enormous gap, show-
ing 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.^
" But if we consider how such deposits are now forming,
Ave shall find that the thinning out of the beds of each
formation, and their restriction to irregular bands and
patches, is exactly what we should expect. The enormous
quantity of sediment continually poured into the sea by
rivers, gradually subsides to the bottom as soon as the
motion of the 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 fine mud and clay is carried
out to considerable distances. Thus all stratified deposits
1 The followiug statement of the depths at which the Paheozoic forma-
tions have been reached in various localities in and round London was
given by Mr. H. B. Woodward in his address to the iSiorwich C4eo]ogical
Society "in 1879 :—
Deep JVclh throit'jh the Tcrtianj and Cretaceous Formations.
Harwich at 1 , 022 feet reached Carboniferous Rock.
Kentish Town ,, 1,114 ,, ,, Okl Red Sandstone.
Tottenham Court Road,, 1,064 ,, ., Devonian.
Biackwall :, 1,004 ,, ,, Devonian or Old Red Sandstone.
Ware ], 800 ., ., Silurian (Wenlock Shale).
We thus find that over a wide area, extending from Loudon to Ware and
Harwich, the whole of the formations from the Oolite to the Permian arc
wanting,' the Cretaceous resting on the Carboniferous or older Palaeozoi(;
rocks ; and the same deficiency extends across to Belgium, where the
Tertiary beds are found resting on Carboniferous at a depth of less than
400 feet.
CHAP. X THE EARTH'S AGE 219
will form most quickly near the shores, and will thin out
rapidly at greater distances, little or none being formed in
the depths of the great oceans. This important tact was
demonstrated by the specimens of sea-bottom examined
during the voyage of the Challevr/cr, all the " shore
deposits" being usually confined within a distance of 100
or 150 miles from the coast ; while the " deep-sea deposits "
are either jijurcly organic, being formed of the calcareous or
siliceous skeletons of globigerina,', radiolarians, and
diatomacea3, 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 arc carried by wind or by water over the widest
oceans.
From the preceding considerations we shall be better
able to ajDpreciate the calculations as to the thickness of
stratified deposits made by geologists. Professor Ramsay
has calculated that the sedimentary rocks of Britain alone
have a total maximum thickness of 72,600 feet ; while
Professor Haughton, from a survey of the whole world,
estimates the maximn/m. thickness of the known stratified
rocks at 177,200 feet. Now these maximuin thicknesses of
each deposit will have been produced only where the con-
ditions were exceptionally fiivourable, either in deej:) water
near the mouths of great rivers, or in inland seas, or in
places to which the drainage of extensive countries was
conveyed by ocean currents ; and this great thickness will
necessarily be accompanied by a corres23onding thinness, or
complete absence of deposit, elsewhere. How far the
series of rocks found in any extensive area, as Europe or
North America, represents the whole series of deposits
which have been made there we cannot tell ; but there is
no reason to think that it is a very inadequate rej)resenta-
tion of their maximvm thickness, though it undoubtedly is
of their extent and hull: When we sec in 1k)W many
distinct localities patches of the same formation occur, it
seems improbable that the whole of the deposits formed
during any one ])eriod sliould have been destroyed, even in
such an area as Europe, while it is still more iiupmbable
that they sliould be so destroved over the whole world ; and
220 ISLAXD LIFE
if any considerable portion of them is left, that portion may
give a fair idea of their average, or even of their maximum,
thickness. In his admirable paper on " The Mean Thick-
ness of the Sedimentary Rocks," ^ Dr. James Croll has
dwelt on the extent of denudation in diminishing 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 denuda-
tion." This is perfectly true, and yet tlie mean thickness
of that portion of the sedimentary 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 ; Avhile, except in the rare case of
an extensive formation being quAte horizontal, and wholly
exposed to the sea or to the atmosphere, denudation can
have no tendency to diminish the thickness of any entire
deposit.^ Unless, therefore, a formation is completely
destroyed by denudation in every part of the world (a thing
very improbable), we may have in existing rocks a not
very inadequate representation of the nieaii thickness of all
that have been formed, and even of the maximum thick-
ness of the larger portion. This will be the more likely
because it is almost certain that many rocks contempor-
aneously formed are counted by geologists as distinct for-
mations, whenever they difler in lithological character or
in oro'anic remains. But we know that limestones, sand-
stones, and shales, are always formnig at the same time :
'' Gculogical Magazine, A'ol. YIIL, March, 1871.
- Mr. C. Lloyd Morgan has Avell ilhistrated this point by comparing tlic
generally tilted-up strata denuded on their edges, to a library in Avhich a
fire had acted on the exposed edges of the books, destroying a great mass
of literature but leaving a portion of each book in its -[dace, -which portion
represents the thickness but not the size of the book. {Geological Ma rjadnc,
1878, p. 161.)
THE EARTH'S ACK 221
while a great difference in organic remains may arise from
comparatively slight changes of geographical features, ov
from difference in the depth or purity of the water in whicJi
the animals lived.^
How to Estimate the Averaye Bate of De2W6Uioii of the
Sedimentary Boels. — But if we take the estimate of
Professor Haughton (177,200 feet), which, as we have seen,
is probably excessive, for the maximum thickness of the
sedimentary rocks of the globe of all known geological
ages, can we arrive at any estimate of the rate at which
they were formed ? Dr. Croll has attempted to make such
an estimate, but he has taken for his basis the mean
thickness of the rocks, which we have no means whatever
of arriving at, and which he guesses, allowing for denuda-
tion, to be equal to the mciximinn thickness as measured
by geologists. The land-area of the globe is, according to
Dr. Croll, 57,000,000 - square miles, and he gives the
coast-line as 116,000 miles. This, however, is, for our
purpose, rather too much, as it allows for bays, inlets, and
the smaller islands. An approximate 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
100 or 150 miles, but by far the larger portion of tlu'
matter brought down from the land will be deposited com-
paratively close to the shore ; that is, Avithin twenty or
thirty miles. If we suppose the portion deposited beyi^nd
thirty miles to be added to the deposits witliin tluit
distance, and the whole reduced to a uniform thickness in
a direction at right angles to the coast, we should })r(tl)ably
include all areas where deposits of the maxiniuni thickness
^ Professor J, Young thinks it idglily probablo tliat— '" tlie Lowor (in-on-
sand is contemporaneous witli part of the Chalk, so were parts of tlic
Wealden ; nay, even of the Purheck n portion nnist liave l>eon furnung
while the Cretar-eous sea ^vas gradually deepening southward and west-
ward." Yet these deposits are always arranged successively, and their
several thicknesses added together to obtain the total thickness of the
formations of the country. (See Presidential Address. Sect. ( '. Hritish
Association, 1876.)
' Mr. John Murray in his more careful estimnte iiiak«-s it ^Uuit .'>1A
millions.
222 ISLAND LIFE tart i
are forming at the present time, along with a large but
unknown proportion of surface where the deiDosits were far
below the maximum thickness. This follows, if we con-
sider 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 limitations 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 exten-
sive. If, therefore, Ave take a width of thirty miles along
the whole coast-line of the globe as representing the area
over which deposits are forming, corresponding to the
maximum tliickness as measured by geologists, we shall
certainly over rather than under-estimate the possible rate
of deposit.^
NoAv a coast line of 100,000 miles with a width of 30
gives an area of 3,000,000 square miles, on which the
denuded matter of the whole land-area of 57,000,000 square
^ As by far the larger portion of the denuded matter of the glohe passes
to the sea through coni|)aratively few great rivers, the deposits must
often be confined to very limited areas. Thus the denudation of the vast
]\Iississippi basin must be almost all de})osited in a limited portion of the
(iulf of Mexico, that of the Nile within a small area of tlie Eastern
]\Iediterranean, and that of the great rivers of China — the Hoang 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 deposits ; so that thirty miles in width along the whole of the coasts
of the globe will probably give an area greater than that of the area of
average deposit, and certainly greater tlian that of maximnm deposit, which
is the basis on which I have here made my estimates. In the case of the
Mississippi, it is stated by Count Pourtalcs that along the i)lateau between
the mouth of the river and the southern extremity of Florida for two
hundred and fifty miles in width the bottom consists of clay with some
sand and but few Rhizopods ; but beyond this distance the soundings
brought up either Hhizopod shells alone, or these mixed with coral sand,
Xullipores. and other calcareous organisms (Dana's Mamial of Geology,
2nd Ed. p. 671). It is probable, therefore, that a large proportion of the
entire mass of sediment brought doAvn by the ^lississippi is deposited on
the limited area above indicated.
Professor Dana further remarks : "Over interior oceanic basins as well
as off a coast in cpiiet depths, fifteen or twenty fathoms and beyond, the
deposits are mostly of fine silt, fitted for making fine argillaceous rocks,
as shales or slates. AVhen, however, the depth of the ocean falls off
below a hundred fathoms, the deposition of silt in our existing oceans
mostly ceases, imless in tlie case of a great Itank along the border of a
continent. "'
THE EARTH'S AGE 223
miles is deposited. As these two areas arc a^s 1 t<» 1!), it
follows that deposition, as measured by maximum thickness,
goes on at least nineteen times as fast as denudation —
in'obably very much faster. But the mean rate of denuda-
tion over the whole eartli is about one foot in three thousand
years; therefore the rate of maximum deposition will be at
least 19 feet in the same time ; and as the total maxiumm
thickness of all the stratified rocks of the globe is, acccjrding
to Professor Haughton, 177,200 feet, the time required to
produce this thickness of rock, at the present rate of
denudation and deposition, is only 28,000,000 years.^
The Rate of Geological Change F^rolahly Greater in verg
Remote Times. — The opinion that denudation and deposition
went on more rapidly in earlier times owing to tlie frequent
occurrence of vast convulsions and cataclysms was strenu-
ously opposed by Sir Charles 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 wdiole series of geological
formations. But while upholding the soundness of the
views of the '' uniformitarians " as opposed to the "con-
vulsionists," we must yet admit that there is reason for
believing in a gradually increasing intensity of all telluric
action as we go back into past time. This subject has
been well treated by Mr. W. J. Sollas,- who shows that, if,
as all physicists maintain, 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 phenomena. With greater heat there would be
a more extensive aqueous atmosphere, and, perhaps, a
greater difference between equatorial and polar tempera-
tures ; hence more violent winds, heavier rains and snows.
1 From the same data Professor Ilauj^'liton estimates a minimum of 200
million years for the duration of geological time ; but he arrives at this
conclusion by supposing the products of denudation to be uniformly
spread over the v-liole S'-d-hottom instead of over a narrow belt near tlie
coasts, a supposition entirely opposed to all the known facts, and which
had l)eeu shown by Dr. Croll, five vears previously, to be altogt-tlier erro-
neous. (See Nature, Vol. XVIII., p. 268, where Professor Haughton's
paper is given as read before the Royal Society.)
- See Ocological Magazine for 1877, p. 1.
224 ISLAND LIFE
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 contraction — 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 denudation.
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 aj^pears 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 upheaval 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 they did i^roduce would certainly be in the direction
here indicated, and as several causes are acting together,
their combined effects may have been by no means un-
important. It must also be remembered that such an
increase of the primary forces on which all geologic change
depends would act with great effect in still further in-
tensifying those alternations of cold and warm periods in
each hemisphere, or, more frequently, of excessive and
equable seasons, which have been shown to be the result of
astronomical, combined with geographical, revolutions; and
this would again increase the rapidity of denudation and
deposition, and thus still further reduce the time required
for the production of the known sedimentary rocks. It is
evident therefore that these various considerations all
combine to prove that, in supposing that the rate of
denudation has been on the average only what it is now,
we are almost certainly over-estimating the time required
to have produced the whole series of formations from the
Cambrian upwards.
Value of the PrececUiuj Estimate of Geological Time. — It
is not of course supposed that the calculation here given
^HAP. X THE EARTH'S AGE 225
makes any api^roacli 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, whicli are not guessed
but the result of actual measurement ; such arc, the amount
of solid matter carried doAvn by rivers, the width of the
belt within which this matter is mainly deposited, and the
maximum thickness of the known stratified rocks.^ A
considerable but unknown 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 sub-aerial
denudation, but it is now believed to be comparatively
slow in its action.^ Whatever it may be, however, it adds
to the rate of formation of new strata, and its omission
from, the calculation is again on the side of making the
lapse of time greater rather than less than the true amount.
Even if a considerable modification should be needed in
some of the assumptions it has been necessary to make,
the result must still show that, so far as the time required
for the formation of the known stratified rocks, the
hundred 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 independent standpoints, of Pro-
fessor Huxley and Professor Ramsay.
Organic Modification Dependent on Change of Conditions.
^ In his reply to Sir AV. Thomson, Professor Huxley assumed one foot
iu a thousand years as a not improbable rate of deposition. The above
estimate indicates a far higher rate ; and this follows from the well-ascer-
tained fact, that the area of de])osition is many times smaller than the area
of denudation,
^ Dr. Croll and Sir Archibald Cieikie have shown that marine denudation
is very small in amount as compared with sub-aerial, since it acts only locally
on the edge of the land, whereas the latter acts over every foot of the
surface. Mr. AV. T. Blanford argues that the ditference is still greater in
tropical than in temperate latitudes, and arrives at the conclusion that—
"If over British India the effects of marine to those of fresh-water denu-
dation in removing the rocks of the country be estimated at 1 to 100, I
believe that the result of marine action will be greatly overstated " {Geo-
logy and Zoology of Abyssinia, p. 158, note). Xow, as our estimate of
the rate of sub-aerial denudation cannot pretend to any jirecise accuracy,
we are justified in neglecting marine denudation altogether, especially as
we liavc no method of estimating it for the whole eartli with any approach
to correctness.
226 ISLAND LIFE
. Having thus shown that the physical changes of the
earth's surface may have gone on much more rapidly and
occupied much less time than has generally been supposed,
we have now to inquire whether there are any considera-
tions which lead to the conclusion that organic changes
may have gone on with corresponding rapidity.
There 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 con-
ditions or environment. If the external world remains
for a moderate period unchanged, the organic world soon
reaches a state of equilibrium through the struggle for
existence ; each species occupies its j)lace 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 extinction 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 existence of some of the
higher animals. Mr. Darwin says : — *' Perhaps Paraguay
offers the most curious instance of this ; for here neither
cattle, nor horses, nor dogs have ever run wild, though
they swarm southward and northward in a wild state ; and
Azara and Rengger have shown tliat this is caused by the
greater number in Paraguay of a certain fly, which lays
its eggs in the navels of these animals when first born.
The increase of these flies, numerous as they ai'e, must be
ciiAP. >^ THE RATP] OF ORGANIC CHANGE 227
habitually checked by some means, probably by other
parasitic insects. Hence, if certain insectivorous birds were
to decrease in Paraguay, the parasitic insects would
probably increase ; and this would lessen the number of
navel-frequenting flies — then cattle and horses would run
wild; and this would certainly alter (as indeed I have
observed in parts of South America) the vegetation : this
again would largely affect the insects, and this, as we have
seen in Staffordshire, the insectivorous birds, and so on-
wards in ever increasing circles of complexity."
Geographical changes would be still more important,
and it is almost impossible to exaggerate the modifications
of the organic world that might result from them. A sub-
sidence of land separating 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 this cause alone ; but more import-
ant would be its effect by isolating small groups of in-
dividuals of many species and thus 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 flourish 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 the strait which
divided them. Numbers of animals would now be brought
into competition for the first time. New enemies and new
competitors would appear in every part of the country ;
and a struggle would commence Avhich, after many fluc-
tuations, would certainly result in the extinction of some
species, the modification of others, and a considerable
alteration in the proj^ortionate numbers and the geograi)h-
ical distribution of almost all.
Any other changes which led to the iutcrmingling of
species whose ranges were usually separate would produce
corresponding results. Thus, increased severity of winter
or summer temperature, causing southward migrations and
the crowdiiigtogether of the productions of distinct regions,
must inevitably produce a struggle for existence, which
would lead to many changes both in tlie characters and
228 ISLAND LIFE part t
the distribution of animals. Slow elevations of the land
would produce another set of changes, by affording an ex-
tended area in which the more dominant species might in-
crease their numbers ; and by a greater range and variety
of alpine climates and mountain stations, affording room
for the development of new forms of life.
Gcograioliical Mutations as a Motive Foioer in Bringinf/
ahout 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 permanent 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 revolutionise 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
repeated unions and sejDarations of the land masses of
the globe, joining together continents which were before
divided, and breaking w^ others into great islands or
extensive archipelagoes. Such alterations of the means
of transit would probably affect the organic world even
more profoundly than the changes of area, of altitude, or
CHAr. X THE RATE OF ORGANIC CHANGE 229
of climate, since they afforded the means, at long intervals,
of bringing the most diverse forms into competition, and
of spreading all the great animal and vegetable tyj)es
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 thus
had time to become modified into a variety of distinct
forms, some of which became so well adapted to specifd
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 become extinct
had they been always subject to the competition of the
more highly organised animals. As examples of such
excessively archaic forms, we may mention the mud-fishes
and the ganoids, confined to limited fresh-water areas;
the frogs and toads, which still maintain themselves
vigorously in competition with higher forms ; and among
mammals the Ornithorhynchus and Echidna of Australia ;
the whole order of Marsupials— which, out of Australia,
where they are quite free from competition, only exist
abundantly in South America, which was certainly long
isolated from the northern continents ; the Insectivora,
which, though widely scattered, are geuerally nocturnal or
subterranean in their habits ; and the Lemurs, which are
most abundant in Madagascar, Avhere they have long been
isolated, and almost removed from the competition of
higher forms.
Glimatal Revolutions as an Agent in Producing Organic
Changes. — The geograj^hical and geological changes we
have been considering are probably those which have been
most effective in bring^incr about the OTeat features of the
distribution of animals, as well as the larger movements
in the development of organised beings; but it is to the
alternations of warm and cold, or of uniform and excessive
climates — of almost perpetual spring in arctic as well as
in temperate lands, with occasional phases of cold culmin-
ating at remote intervals in glacial epochs, — that we nuist
impute some of the more remarkable changes both in the
specific characters and in the distribution of organisms.^
^ Agassiz appears to have been the first to suggest that the }uincipal
230 ISLAND LIFE part i
Although the geological evidence is opposed to the belief
in early glacial epochs except at very remote and distant
intervals, there is nothing which contradicts the occurrence
of repeated 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 low
excentricity must certainly have produced changes of
climate of considerable importance to the life of animals
and plants. During periods of high excentricity with
summer in ]ierilielion, that season would be certainly very
much hotter, while the winters would be longer and
colder than at present ; and although geographical con-
ditions might prevent any permanent increase of snow
and ice even in the extreme north, yet we cannot doubt
that the whole northern hemisiDhere w^ould then have a
very different climate than when the changing phase of
precession brought a very cool summer and a very mild
w^inter — a perpetual spring, in fact. Now, such a change
of climate would certainly be calculated to bring about a
considerable change of species, both by modification and
migration, Avithout 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 consider-
able modifications in the fauna and flora of both countries
would be the result, although it is impossible to predict
epoclis of life extermination were epochs of cold ; and Dana thinks that
two at least such epochs may be recognised, at the close of the Paleozoic
and of the Cretaceous periods — to which we may add the last glacial epoch.
CTiAr. X THE RATE OF ORGANIC CHANGE 231
what the precise changes would be. We cmu safely say,
however, that some species would stand the clian_<'-e better
than others, while it is highly ])robable that some would be
actually benefited by it, and that others Avould be injured.
But the benefited would certainly increase, and the
injured decrease, in consequence, and thus a .series of
changes would be initiated that might lead to most
important results. 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 expense of others
not so readily modified ; and hence would arise on the one
hand extinction of species, and on the other the pro-
duction of new forms.
But this is the very least amount of change of climate
that would certainly occur every 10,500 years wlien tliere
was a high excentricity, for it is impossible to doubt tliat
a varying distance of the sun in summer from 86 to 99
millions of miles (which is what occurred during — as
supposed — the Miocene period, 850,000 years ago) would
produce an important difference in the summer tem-
perature and in the actinic influence of sunshine on
vegetation. For the intensity of the sun's rays would
vary as the square of the distance, or nearly as 74 to OcS,
so that the earth would be actually receiving one-fourth
less sun-heat during summer at one time than at the
other. An equally high excentricity occurred 2,500,000
years back, and no doubt was often reached during still
earlier epochs, while a lower but still very high excen-
tricity 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 cc^ndi-
tions so as to produce climatic alterations in difierent
directions, giving to the ancient lands either dry or wet
seasons, storms or calms, equable or excessive temperatures,
in a variety of combinations of which the earth perhaps
affords no example under the present low phase of
232 ISLAND LIFE
excentricity and consequent slight inequality of sun-
heat.
Present Conclition of the Earth One of Exceptional Stability
as Regards Climate. — It will be seen, by a reference to the
diagram at 23age 171, that during the last three million
years the excentricity 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 excentricity 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 three million years, for which we have
tables, was in any way exceptional as regards the de-
gree or variation of excentricity ; 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 excentricity 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 considerable changes of climate and the con-
sequent 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 stalility of
sjKcies.
But it is from this very period of exceptional stahility
that we obtain our only scah for measuring the rate of
organic change. It includes not only the historical joeriod.
ciiAr. X MEASUREMENT OF GEOLOGICAL TIME 233
but that of the Swiss Lake dwellings, the Danish slioll-
mounds, our peat-bogs, our sunken forests, and many of our
superficial alluv^ial deposits — the wdiole in fact, of tlic 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 erpoch was passing away.
Now throughout all these ages we find no indication of
change of species, and but little, comparatively, of migra-
tion. We thus get an erroneous idea of the lynaancnci:
and stability of specific foQins, due to the ]3eriod immediately
antecedent to our own being a period of cxcciUional per-
manence and stability as regards climatic and geogi'aphical
conditions.^
Date of Last Glacial Epoch and its Bearing on the
Measurement of Geologiccd Time.—T)\YQci\y we go back
from this stable period we come ujoon changes both in the
forms and in the distribution of species ; and Avhen we
pass beyond the last glacial epoch into the Pliocene period
we find ourselves in a comparatively new world, surrounded
by a considerable number of species altogether different
from any which now exist, together with many others
which, though still living, now inhabit distant regious.
It seems not improbable that what is termed the Pliocene
period, was really the coming on of the glacial epoch, and
this is the opinion of Professor Jules Marcou.- According to
our views, a considerable amount of geographical change
must have occurred at the change from the Miocene to
the Pliocene, favouring the refrigeration of the northern
hemisphere, and leading, in the way already pointed out,
to the glacial epoch whenever a high degree of excentricity
^ This view was, I believe, first ])ut fortli by myself in a })a])er read
before the Geological Section of the Britisli Association in 1869, aii«l
subsequently in an article in Nature, .\o\. I, \\ A:A. It was also stated
by Mr. S. B. K. Skertchley in his rhvfticnJ Sijstcm of the Univcne, p. 363
(1878) ; but we both I'ounded it on what I now consider the erroneous
doctrine that actual glacial ep0(dis rccurre<l each 10,500 years during
periods of liigh excentricity.
2 Explication d'une seconde edition de la Carle Geoloyo/nc (fc la T<r/r
(1875\ p. 64.
234 ISLAND LIFE
prevailed. As many reasons combine to make us fix the
height of the glacial epoch at the period of high excen-
tricity which occurred 200,000 years back, and as the Plio-
cene period was probably not of long duration, w^e must
suppose the next great phase of very high excentricity
(850,000 years 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 concurrence with favourable geographical condi-
tions, it led to uninterrupted warm climates in the
temperate and northern zones. This, however, did not
prevent the occurrence of local glaciation 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 occTir at an elevation of over 6,000
feet, while Eocene beds occur at nearly 10,000 feet. But
since that time there has been a vast amount of denuda-
tion, so that these rocks may have been at first raised much
higher than we now find them, and thus a considerable
portion of the Alps may have been more elevated than
they are now. This would certainly lead to an enormous
accumulation of snow, which would be increased when
the excentricity reached a maximum, as already fully
explained, 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 earher epoch of great altitude
in the Alps coinciding with the very high excentricity
2,500,000 years ago, may have caused the local glaciation
of the Middle Eocene period when the enormous 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 indic-
tions 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 Zealand a
delightful climate and a rich vegetation of Metrosideros,
CHAP. X MEASUREMENT OF GEOLOGICAL THIK 2^r,
fuchsias and tree-ferns on the very herders of lm<_;r
glaciers, descending to witliin 700 feet of tlie sea-level.
It is not pretended that these estimates of geological time
liave any more value than probahle guesses ; ])ut it is
certainly a curious coincidence that two remarkable
periods of high excentricity sliould have occurred, at sucli
periods and at such intervals apart, as very well accord
with the comparative remoteness of the two deposits in
wdiich undoubted signs of ice-action have been found, and
that both these are localised 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 Princiioles of Geology, Sir
Charles Lyell, taking the amount of change in the species
of mollusca as a guide, estimated the time elapsed since
the commencement of the Miocene as one-third that of tlie
whole Tertiary epoch, and the latter at one-fourth tliat of
geological time since the Cambrian period. Professor
Dana, on the other hand, estimates the Tertiary as only
one-fifteenth of the Mesozoic and Pala3ozoic combined. On
the estimate above given, founded on the dates of phases
of high excentricity, we shall arrive at about four million
years for the Tertiary epoch, and sixteen million years for
the time elapsed since the Cambrian, according 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 all events, satisfactory that the various measures
result in figures of the same order of magnitude, which is
all one can expect w^hen discussing so difficult and ex-
ceedingly 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 hundreds of millions of years, wliich have sometimes
been indicated by geologists, are neither necessary nor
warranted by the facts at our command ; while the present
result places us more in harmony with the calculations of
physicists, by leaving a very wide margin between geo
logical time as defined by the fossiliferous rocks, and that
236 ISLAND LIFE
far more extensive period which includes all possibility of
life upon the earth.
Concluding Eemar'ks. — In the present chapter I have
endeavoured to show that, combining the measured rate of
denudation with the estimated thickness and probable
extent of the known series of sedimentary rocks, we may
arrive at a rude estimate of the time occupied in the for-
mation of those rocks. From another point of departure —
that of the probable date of the Miocene period, as deter-
mined by the epoch of high excentricity supposed to have
aided in the production of the Alpine glaciation during
that period, and taking the estimate of geologists as to the
proportionate amount of change in the animal world since
that epoch — we obtain another estimate of the duration of
geological time, which, though founded on far less secure
data, agrees pretty nearly with the former estimate. The
time thus arrived at is immensely less than the usual
estimates of creolooists, and is so far within the limits of
the duration of the earth as calculated by Sir William
Thomson, as to allow for the development 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 j^i^ocli-^ced by high
excentricity and opposite phases of precession, even though
these did not lead to glacial epochs, we have a motive
power well calculated to produce far more rapid organic
changes than have hitherto 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
proportioned to the comparatively rapid changes in the
earth's surface.
We have now finished the series of preliminary studies
of the biological conditions and physical changes which
have affected the modification and dispersal of organisms,
and have thus brought about their actual distribution on
CHAP. X MEASUREMENT OF GEOLOGICAL TIME 237
the surface of the earth. These studies will, it is believed,
pkce us in a condition to solve most of the problems
presented by the distribution of animals and plants, \vhL'n-
ever the necessary facts, both as to their distribution Jiud
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 sufficiently explained in our preface.
PAET II
IN^SULAR FAUNAt^ AND FLORA.^
CHAPTER XI
THE CLASSIFICATION OF ISLANDS
Importance of Islands in the Study of the Distribution of Organisms —
Classification of Islands with Reference to Distribution — Continental
Islands — Oceanic Islands.
In the preceding chapters, formiug the first part of our
work, we have discussed, more or less fully, the general
features presented by animal distribution, as well\s 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 phenom-
ena as are presented by the islands of the globe.
Imj)OTtancc of Islands in the Studi/ of the Distrihition of
Organisms. — Islands possess many advantages for the study
of the laws and plienomena of distribution. As com])ared
with continents they have a restricted area and definite
boundaries, and in most cases their geograj)liical and
biological limits coincide. The number \)f speci(\s and ..f
genera they contain is always mucli smaller than in the
242 ISLAT^D LIFE
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 often direct
and simple, and even when more complex are far easier to
comprehend than those of continents ; and they exhibit
besides certain influences on the forms of life and certain
peculiarities in their distribution which continents do not
present, and whose study offers many points of interest.
In islands we have the facts of distribution pre-
sented to us, sometimes in their simplest forms, in other
cases becoming gradually more and more complex ; and we
are therefore able to proceed step by step in the solution
of the problems they present. But as in studying these
problems we have necessarily to take into account the
relations of the insular and continental faunas, we 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 not too much to say
that when we have mastered the difficulties presented by
the peculiarities of island life we shall find it comparatively
easy to deal with the more complex and less clearly de-
fined problems of continental distribution.
Classification of Islands u'itli Reference to Distribution. —
Islands have had two distinct modes of origin — they have
either been separated from continents of which they are
but detached fragments, or they have originated in the
ocean and have never formed part of a continent or any
large mass of land. This difference of origin is funda-
mental, and leads to a most important difference in their
animal inhabitants; and we may therefore first distinguish
the two classes — oceanic and continental islands.
Mr. Darwin appears to have been the first writer who
called attention to the number and importance, both from
a geological and biological point of view, of oceanic
islands. He 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. He also showed the
connection of these two phenomena, and maintained
that none of the islands so characterised had ever formed
CHAP. XT THE CLASSIFICATION OF ISLANDS 243
part of a continent. This was quite opposed tu the
opinions of the scientific men of the day, who ahnost all
held the idea of continental extensions, and of oceanic
islands being their fragments, and it was long before Mr.
Darwin's views obtained general acceptance. Even now
the belief still lingers ; and we continually hear of old
Atlantic or Pacific continents, of " Atlantis " or " Lemuria,"
of which hypothetical lands many existing islands, although
wholly volcanic, are thought to be the remnants. We
have already seen that Darwin connected the peculiar
geological structure of oceanic islands with the permanence
of the great oceans which contain them, and we have
shown that several 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 always separated
from them by very deep sea, entirely without indigenous
land mammalia or amphibia, but with a f\iir number of
birds and insects, and usually with some reptiles. This
definition will exclude only two islands which have been
sometimes classed as oceanic — New Zealand and the
Seychelles. Rodriguez, which was once thouglit to be
another exception, has been shown by the explorations
during the Transit of Venus Expedition to be essentially
volcanic, with some upraised coralline limestone.
Continental Islands. — Continental islands are always
more varied in their geological formation, containing both
ancient and recent stratified rocks. They are 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 are always situated on sub-
merged 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 those of the continent, or if othor-
Ji 2
244 ISLAXD LIFE part ii
wise, the difference consists in the presence of closely allied
species of the same types, with occasionally a very few
peculiar genera. They possess in fact all the character-
istics of a portion of the continent, separated from it at a
recent geological period.
Ancient continental islands differ greatly from the pre-
ceding in many respects. They are not united to the adja-
cent continent by a shallow bank, but are usually separated
from it by a depth of sea of several hundreds to more than
a thousand fathoms. In geological structure they agree
generally with the more recent islands ; like them they
possess mammalia and amphibia, usually in considerable
abundance, as well as all other classes of animals ; but
these are highly peculiar, almost all being distinct species,
and many forming distinct and peculiar genera or families.
They are also well characterised by the fragmentary nature
of their fauna, many of the most characteristic continental
orders or families being quite unrepresented, while some
of their animals are allied, not to such forms as inhabit
the adjacent continent, but to others found only in remote
parts of the world. This very remarkable set of cliaracters
marks off the islands which exhibit them as a distinct
class, which often present the greatest anomalies and most
difficult problems to the student of distribution.
Oceanic Islands. — The total absence of warm-blooded
terrestrial animals in an island otherwise well suited to
maintain them, is held to i^rove that such island is no mere
fragment of any existing or submerged continent, but one
that has been actually produced in mid-ocean. It is true
that if a continental island were to be completely sub-
merged for a single day and then again elevated, its higher
terrestrial animals would be all destroyed, and if it were
situated at a considerable distance from land it would be
reduced to the same zoological condition as an oceanic
island. But such a complete submergence and re-eleva-
tion appears never to have taken place, for there is no
single island on the globe which has the physical and geo-
logical features of a continental, combined with the zoo-
logical features of an oceanic island. It is true that some
of the coral-islands may be formed upon submerged lands
CHAP. x[ OCEANIC ISLANDS. 21.'.
of a continental character, but we have no proof of this ;
and even if it were so, the existing islands are to all intents
and purposes oceanic.
We will now pass on to a consideration of some of the
more interesting examples of these three classes, beginning
with oceanic islands.
All the animals which now inhabit such oceanic islands
must either themselves have reached them by crossnig the
ocean, or be the descendants of ancestors who did so. Let
us then see what are, in fact, the animal and vegetable in-
habitants of these islands, and how 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 afford us
an important clue to some of the most efficient means of
distribution among several classes of animals.
CHAPTER XII
OCEANIC ISLANDS : — THE AZORES AND BERMUDA
The AzoiiEs, oe. WESTEnx Islands
Position and Physical Features — Chief Zoological 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
Seeds — Birds as Seed-Carriers — Facilities for Dispersal of Azorean Plants
— Important Deduction from the Peculiarities of tlie Azorean Fauna
and Flora.
Bekmuda
Position and Physical Features — The Red Clay of Bermuda— Zoology of
Bermuda — Birds of Bermuda — Comparison of the Bird Faunas of Ber-
muda and the Azores — Insects of Bermuda — Land ]\Iollusca — Flora of
Bermuda — Concluding Remarks on the Azores and Bermuda.
We will commence our investigation into the phenomena
presented by oceanic islands, with two groups of the North
Atlantic, in which the facts are of a comparatively simple
nature and such as to afford us a valuable clue to a solu-
tion of the more difficult problems Ave 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 coral-
line ; 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
CHAP, xir OCEANIC ISLANDS 247
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, nine in number, form a widely scattered
group, situated between 37° and 89° 40' N. Lat. and
stretching in a south-east and north-west cHrection over a
distance of nearly 400 miles. The largest of the islands,
San Miguel, is about forty miles long, and is one of the
nearest to Europe, being rather under 900 miles from the
coast of Portugal, from which it is separated by an ocean
2,500 fathoms deej). The depth between the islands does
not seem to be known, but the 1,000 fathom line encloses
the whole group pretty closely, while a depth of about
1,800 fathoms is reached within 800 miles in all directions.
These great dejoths render it in the highest degree improb-
able that the Azores have ever been united with the
European continent ; while their being wholly volcanic is
equally opposed to the view of their having formed joart of
an extensive Atlantis including Madeira and the Canaries.
The only exception to their volcanic structure is the
occurrence in one small island only (Santa Maria) of some
marine deposits of Upper Miocene age — a fact which
proves some alterations of level, and perhaps a greater
extension of this island at some former period, but in no
way indicates a former union of the islands, or any greater
extension of the whole group. It proves, however, that
the group is of considerable antiquity, since it must date
back to Miocene times ; and this fict may be of im-
portance in considering the origin and peculiar features of
the fauna and flora. It thus ap])ears that in all physical
features the Azores correspond strictly with our ])hysical
definition of '• oceanic islands," while their \ri\-nx distance
248
ISLAXD LIFE
I'AKT II
from any other land, and the depth of the ocean around
them, make them typical examples of the class. We
should therefore expect them to be equally typical in their
fauna and flora ; and this is the case as regards the most
important characteristics, although in some points of detail
they present exceptional phenomena.
OUTLINE MAP OF THE AZORES.
Note,— The light tint shows where the sea is less than 1,000 fathoms deep.
The dark tint ,, ,, ,, more than 1,000 fathoms deep.
The figures show depths in fathoms.
Chief Zoological Features of the Azores}— 11\\q great
feature of oceanic islands — the absence of all indigenous
land-mammalia and amphibia — is well shown in this
^ For most of the facts as to tlie zoology and botany of these islands, I
am indebted to Mr. Godman's valnalde work — Natural History of the
Azores or Western Islands, ])y Frederick Du Cane Godnian, F L.H., F.Z.S.,
&c., London, 1870.
TIIK A/()1;KS 249
group ; and it is even carried further, so as to include all
terrestrial vertebrata, there being no snake, lizard, frog, or
fresh-water fish, although the islands arc sufficiently exten-
sive, possess a mild and equable climate, and are in every
way adapted to support all these groups. On the other
hand, flying creatures, as birds and insects, are abundant ;
and there is also one flying mammal — a small Ein'opean
bat. It is true that rabbits, weasels, rats and mice, and a
small 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 human
agency. The same may be said of the gold-fish and eels
now found in some of the lakes, there being not a single
fresh-Avater fish which is truly indigenous to the islands.
When we consider that the nearest part of the gi'<jup is
about 900 miles from Portugal, and more than 550 miles
from Madeira, it is not surprising that none of these
terrestrial animals can have passed over such a wide
expanse of ocean unassisted by man.
Let us now see 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 powers 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 number,
are more interesting, four only being stragglers, while
eighteen are permanent residents. The following is a list
of these resident land-birds : —
1.
Common Buzzard
{Biiko vidgaris)
2^
Lonrr-oared Owl
{Asio otm)
13
Barn Owl
(Sf.rix flaminca)
4.
Blackbird
[Tardus lucruht)
KnMn
(Enilhacus rubeculii)
0.
lila..k.ui.
{Sylvia (Uricapilla)
250 ISLAND LIFE
7. Gold-crest {Regulus cristatus)
8. Wheatear [Saxicola ccnanthc)
9. Grey AVagtail ... ... {Motacilla sulphur ea)
10. Atlantic ChaflSnch {Fringilla tintillon)
11. Azorean Bullfinch [Pyrrhula murina)
12. Canary ... ... {Serinus canarius)
13. Common Starling {Sturnus vulgaris)
14. Lesser Spotted Woodpecker ... [Dry ohatcs minor)
15. Wood-pigeon [Columha palumhus)
16. Rock Dove [Columha livia)
17. Red-legged Partridge [Caccahis rufa)
18. Common Quail [Coturnix 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 si)ecies while all the rest are
identical with European birds ? In order to answer them,
let us first see what stragglers now actually visit the
Azores from the nearest continents. The four species
given in Mr. Godman's list are the kestrel, the oriole, the
snow-bunting, and the hoopoe ; but he also tells us that
there are certainly others, and adds : " Scarcely a storm
occurs in spring or autumn without bringing one or more
species foreign to the islands ; and I have frequently been
told that swallows, larks, grebes, and other species not
referred to here, are not uncommonly seen at those seasons
of the year."
We have, therefore, every reason to believe that the
birds which are now residents originated as stragglers,
which occasionally found a haven in these remote islands
when driven out to sea by storms. Some of them, no
doubt, still often arrive from the continent, but these
cannot easily be distinguished as new arrivals among those
which are permanent inhabitants. Many facts m.entioned
by Mr. Godman show that this is the case. A barn-owl,
much exhausted, flew on board a whaling-ship when 500
miles S.W. of the Azores ; and even if it had come from
CHAP. XII THE AZORES 2r,l
Madeira it must have travelled quite as far as from
Portugal to the islands. Mr. Godman also shot a single
specimen of the wheatear 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
were 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 establishing itself.
Another fact Avhich is almost conclusive in favour of tlie
bird-population having arrived as stragglers is, that they
are most abundant in the islands nearest to Europe and
Africa. The Azores consist of three divisions — an eastern,
consisting of two islands, St. Michael's and St. Mary's ; a
central of live, Terceira, Graciosa, St. George's, Pico, and
Fayal ; and a western of two, Flores and Corvo. Now had
the whole gTou]3 once been united to the continent, or even
formed parts of one extensive Atlantic island, we should
certainly expect the central group, which is more compact
and has a much larger area than all the rest, to have tlic
greatest number and variety of birds. But the fact tlmt
birds are most numerous in the eastern group, and diminish
as we go westward, is entirely opposed to this theory, while
it is strictly in accordance with the view that they are all
stragglers from Europe, Africa, or the other Atlantic
islands. Omitting oceanic wanderers, and inrluding all
birds which have probably 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 bullfinch (Avhich, however, does not diiier irom the
common European bulltinch more than do some of tlio
varieties of North American birds from their type-sjjecies)
is not difficult ; the wonder rather being that there are
not more peculiar forms. In our third chapter we liavc
seen how great is the amount of individual variation in
birds, and how readily local varieties become established
wherever the physical conditions are sufficiently distinct.
Now we can liardlv have a fn'oator ditVerence of ennditioiis
252 ISLAND LIFE tart ii
than between the cont inent of Europe or North Africa,
and a group of rocky islands in mid-Atlantic, situated in
the full course 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 animals completely isolated under such
conditions. But they 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 does not migrate, and is therefore less likely
to be blown out to sea, more especially as it inhabits woody
districts. A few other Azorean birds, however, exhibit
slight difterences from their European allies.
There is another reason for the very slight amount of
peculiarity presented by the fauna of the Azores as com-
pared with many other oceanic islands, dependent on its
comparatively recent origin. The islands themselves may
be of considerable antiquity, since a few small deposits,
believed to be of Miocene age, have been found on them,
but there can be little doubt that their present fauna, at
all events as concerns the birds, had its origin since the
date of the last glacial epoch. Even now icebergs reach
the latitude of the Azores but a little to the west of them ;
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 7,600 feet high in
Pico, would almost certainly have been covered with per-
petual snow and have sent down glaciers to the sea. They
might then have had a climate almost as bad as that now
endured by the Prince Edward Islands in the southern
hemisphere, nearly ten degrees farther from the equator,
where there are no land-birds whatever, although the
distance from Africa is not much greater than that of the
Azores from Europe, while the vegetation is limited to a
few alpine plants and mosses. This recent origin of the
CHAP. XII THE AZORES
2u'^
birds accounts in a great measure for their identity witli
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.
Insects of the Azores. — Having thus found no difficulty
in accounting for the peculiarities presented by the birds
of these islands, we have only to see how far the same
general principles will apply to the insects and land-shells.
The butterflies, moths, and hymenoptera, are few in num-
ber, and almost all seem to be common European species,
whose presence is explained by the 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 number of
species yet known is 212, of which 175 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 species are not found in
any of the other Atlantic islands, showing that they have
been introduced directly from Europe by causes which
have acted more powerfully here than farther south.
Besides these there are thirty-six species not found in
Europe, of which nineteen are natives of Madeira or the
Canaries, three are American, and fourteen are altogether
peculiar to the Azores. These latter are mostly allied to
species 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 species will be interesting : —
Cahabidj*:.
Anchomcnus apiinoidcs ...Allied to a species from the Canaries.
Bcmhidium hcsjjcrvs Allied to the Euroi)ean B. Uclum.
Dx-naciDA:.
Acfahus godmanni Allied to the Euroi)ean A. dispar.
COLYDIID.*;.
Tarphlufi woUastoni A gcim.s almost ]in(iiliar to tlie Atlaiitir islamis.
254 ISLAND LIFE part ii
ElATERIDiE.
Eeteroderes azoricus Allied to a Brazilian species.
Elastrus dolosus Belongs to a peculiar Madagascar genus '.
MELYPJD/E.
Attains miniaticollis Allied to a Canarian species.
Rhyncophora.
Phlceophagus variabilis ...Allied to European and Atlantic species.
Acalles droucti A Mediterranean and Atlantic genus.
Laparoccrus azoricus Allied to Madeiran species.
Asynonychun godmansi ...k^ecvlidiX genu-s, allied to Brachyderes, oi the
south of Europe.
Neocnemis occidentalis ...A peculiar genus, allied to the European genus
Strophosoomis.
Heteromera.
Helops azoricus Allied to E. v^dcanus of Madeira.
Staphylinid^.
Xenomma melanocepJtal a.. AUied to X filiforme 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
agg or larva state or even as perfect insects, they may be
drifted safely for weeks over the ocean, buried in the light
stems of i^lants or in the solid wood of trees in which many
of them undergo their transformations. Thus we may
explain the presence of three common South American
species (two elaters and a longicorn), all wood-eaters, and
therefore liable to be occasionally brought in floating timber
by the Gulf Stream. But insects are also immensely
more numerous in species than are land-birds, and their
transmission would be in most cases quite involuntary,
and not dependent on their own powers of flight as with
birds; and thus the chances against the same species
being frequently carried to the same island would be
considerable. If we add to this the dependence of so
CHAP. XII THE AZORES 255
many insects on local conditions of climate and vegetation,
and their liability to be destroyed by insectivorous birds,
we shall see that, although there may be a greater proba-
bility of insects as a whole reaching the islands, the chance
against any particular species arriving there, or against the
same species arriving frequently, is much greater than in
the case of birds. The result is, that (as compared with
Britain for example) the birds are, proportionately, much
more numerous than the beetles, while the peculiar species
of beetles are much more numerous than among birds,
both facts being quite in accordance with v/hat we know
of the habits of the two groups. We may also remark,
that the small size and obscure characters of many of the
beetles renders it probable that species now supposed to
be peculiar, really inhabit some parts of Europe or North
Africa.
It is interesting to note that the two families wliich are
pre-eminently wood, root, or seed eaters, are those which
present the greatest amount of speciality. The two
Elateridse alone exhibit remote affinities, the one with a
Brazilian the other with a Madagascar group ; while the
only peculiar genera belong to the Ehyncophora, but are
allied to European forms. These last almost certainly
form a portion of the more ancient fauna of the islands
which migrated to them in pre-giacial times, while the
Brazilian elater appears to be the solitary example of a
living insect brought by the Gulf Stream to these remote
shores. The elater, having its nearest living ally in
Madagascar {Elastrus dolosus), cannot be held to indicate
any independent communication between these distant
islands ; but is more probably a 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 ]\Iada-
gascar and South America, and some to Madagascar and
Australia. The clue to these apparent anomalies is found
in other genera being common to Madagascar, Africa, and
South America, while others are Asiatic or Australian.
Madaj^ascar, in fact, has insect relations witli every ]»art of
256 ISLAND LIFE
the globe, and the only rational explanation of such facts
is, that they are indications of very ancient and once wide-
spread groups, maintaining themselves only in a few
Avidely separated portions of what was at one time or
another the area of their distribution.
Land-shells 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
molluscs 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 un-
disturbed 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 common to Europe or the other Atlantic
islands, while thirty-tAvo 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 exceedingly minute,
and might occasionally be carried on leaves or other
materials during gales of exceptional violence and duration,
while others might be conveyed with the earth that often
sticks to the feet of birds. There are also, 2Drobably, other
unknown means of conveyance ; but however this may be,
the general character of the land-molluscs 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 continent, and have been peopled with
living things by such forms only as in some way or other
have been able to reach them across many hundred miles
of ocean.
The Flora of the Azores. — The flowering-plants of the
Azores have been studied by one of our first botanists, Mr.
H. C. Watson, who has himself visited the islands and
made extensive collections ; and he has given a complete
catalogue of the species in Mr. Godman's volume. As our
1 See Cliap. Y. p. 78.
CHAP, xir THE AZORKS
2r,7
object in the present work is to trace the past history of
the more important islands by means of the forms of life
that inhabit them, and as for this purpose plants are some-
times of more value than any class of animals, it will be
well to take advantage of tlie valuable materials here avail-
able, in order to ascertain how far the evidence derived
from the two organic kingdoms agrees in character; and
also to obtain some general results which may be uf service
in our discussion of more difficult and more complex
problems.
There are in the Azores 480 known species of fiowerin<'--
plaiits and ferns, of which no less than 440 arc 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 conti-
nental extensions to account for the wide dispersal of
objects of their study, it will be well to examine somewhat
closely what these facts really imply.
The Dispersed of Seeds. — The seeds of plants are liable
to be dispersed by a greater variety of agents than any
other organisms, 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 flowering plants have the sexes united
in the same individual, so that a single seed in a state tit
to germinate may easily stock a whole island. The dis-
persal of seeds has been studied by Sir Joseph Hooker,
Mr. Darwin, and many other writers, who have made it
sufficiently clear that they are in many cases liable to be
carried enormous distances. An immense number are
specially adapted to be carried by the wind, through the
possession of down or hairs, or membranous wings or pro-
cesses ; while others are so minute, and produced in such
profusion, that it is difficult to place a limit to the distance
they might be carried by gales of wind or hurricanes.
Another class of somewhat heavier seeds or dry fruits arc
capable of being exposed for a long time to sea-water with-
out injury. Mr. Darwin made many experiments on this
point, and he found that many seeds, especially of Atriplex,
258 iSLAXD LIFE rART ii
Beta, oats, Capsicum, and the potato, grew after 100 days'
immersion, Avhile a large number survived fifty days. But
he also found that most of them sink after a few days' im-
mersion, and this would certainly prevent them being
floated to very great distances. It is very possible, how-
ever, 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 Avhich 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 tlie
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 the
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 found in the Azores, half are,
more or less, fruit-eaters, and these may have been tlie
means of introducing many plants into the islands.
Birds also frequently have small portions of earth on
tlieir feet ; and Mr. Darwin has shown by actual experi-
ment that almost all such earth contains seeds. Thus in
^ Some of Mr. Darwin's experiiiieuts are very interesting and suggestive.
Kipe hazel-nuts sank immediately, but- when dried they floated for ninety
days, and afterwards germinated. An asparagus-plant with ripe berries,
when dried, floated for eighty-five days, and the seeds afterwards germi-
nated. Out of ninety-four dried plants experimented with, eighteen floated
for more than a month, and some for three months, and their powers ot
germination seem never to have been wholly destroyed. Now, as oeeanie
currents vary from thirty to sixty miles a day, such plants under the most
favourable conditions might be carried 90 x 60 -= 5, 400 miles I But even half
of this is ample to enable them to reach any oceanic island, and we must re-
member that till completely water-logged they might be driven along at a
much greater rate by the wind. Mr. Darwin calculates the distance by the
average time of flotation to be 924 miles ; but in such a case as this we
are entitled to take the extreme cases, because such countless thousands of
plants and seeds must be carried out to sea annually that the extreme cases
in a single experiment with only ninety-four plants, must happen hundreds
or thousands of times and with hundreds or thousands of species, naturally,
and thus aff'ord ample opportunities for successful migration. (See Origm
of SlJccies, 6th Edition, p. 325.)
CHAP. XII THE AZORES 259
nine grains of earth on the leg of a woodcock a seed of the
toad-rush was found which germinated ; while a W(MHi(k'(l
red-legged partridge had a ball of earth weigliing six and
a half ounces adhering to its leg, and from this eartli Mr.
Darwin raised no less than eighty-two separate plants of
about five distinct species. Still more remarkable was the
experiment with six and three-quarter ounces of mud from
the edge of a little pond, which, carefully treated under
glass, produced 537 distinct plants ! This is equal to a
seed for every six grains of mud, and when we consider
,how many birds frequent the edges of ponds in search (»f
food, or come there to drink, it is evident that great
mimbers of seeds may be dispersed by this means.
Many seeds have hispid awns, hooks, or prickles which
readily' attach them to the feathers of birds, and a great
number of aquatic birds nest inland on the ground ; and
as these are pre-eminently wanderers, they must often aid
in the dispersal of such plants.^
^ The following remarks, kindly conimunieatt-'d to nic by 'Mv. H. X.
Moseley, naturalist to the Chcdlcngcr, throw much light on the agency oi
birds in the distribution of plants : — "Grisebach (J\y. dcrErdc, Vol. II. p.
196) lays much stress on the wide ranging of the albatross (Diomedea)
across the equator from Cape Horn to the Kurile Islands, and thinks tliat
the presence of the same plants in Arctic and Antarctic regions may l)e
accounted for, possibly, by this fart. I was much struck at Clarion Island
of the Prince Edward*^ group, by observing that the great albatross breeds
in the midst of a dense, low herbage, and constructs its nest of a inound
of turf and lierbage. Some of the indigenous plants, e.g. Acrena, havi-
Howcr-heads which stick like burrs to leathers, &e., and seem specially
adapted for transporation by birds. Besides the albatrosses, various
species of Procellaria and Puffinus, birds which range over immense dis-
tances may, I think, have played a great i)art in the distribution of plants,
and esi»ecially account, in some measure, for the otherwise dillicult fad
(whfn occurring in the tropics), that widely distant islands liavo similar
mountain plants. The Procellaria and Puthnus in nesting, burrow in the
ground, as i'ar as I have seen choosing often jdaces where the vegetation
is tlie thickest. The birds in burrowing get their feathers covered with
vegetable mould, wliich must include si)ores, and often seeils. In high
latitudes the birds often burrow near the sea-level, as at Tristan d'Acunlia
or Kerguelen's Land, but in the tropics they clioose the mountains for then-
nesting-place (Finschand Hartlaub, Ora.dcr J'ifi-und Tvufia-Inscln, 1867,
Kinleitung, p. xviii.). Thus, Puffuius nuyasi nests at the top of the Koro-
basa basaga mountain, A'iti Levu, fifty miles from the sea. A Procellaria
In-eeds in like manner in the high mountains of Jamaica, I believe at 7,000
feet. Peale descrilx's the same habit of ProccUaria rostrala at Tahiti, and
I saw the burrows myself amidst a denst> growth of fern, &<•., at 4, 100 feet
elevation in that island. Phaclhoii has a similar habit. It ne>ts at tho
m ISLAND LIFE PART li
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 floweriijg-plants in Mr. Watson's list, I find that
about forty-five belong t^ genera that have either pappus
or winged seeds ; sixty-five to such as have very minute
seeds ; thirty have fleshy fruits such as are greedily eaten
by birds ; several have hispid seeds ; and eighty-four 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, alders, and firs ; while the only trees or large
shrubs are the Portugal lautel, myrtle, laurestinus, elder,
Laurus canariensis, Myrka faya, and a doubtfully peculiar
junij^er — 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 tliat the truly indigenous flora
of the islands is far more scanty than the number of
plants recorded would imply, because a large but unknown
proportion of the sj^ecies are certainly importations, vol-
untary or involuntary, by man. As, however, the general
character of the whole flora is that of the south-western
peninsula of Europe, and as most of the introduced plants
have come from the same country, it is almost impossible
now to separate them, and Mr. Watson has not attemiDted
to do so. The whole flora contains representatives of
eighty natural orders and 250 genera : and even if we
suppose that one-half the species only are truly indigenous,
crater of Kilaiiea, Hawaii, at 4, 000 feet elevation, and also high up in Tahiti,
In order to account for the transporatiou of the plants, it is not of course
necessary that the same species of Procellaria or Dioniedea should now
range between the distant points where the plants occur. The ancestor of
the now diilering species might have carried the seeds. The range of l^ho
cir.w. xri TPfK AZORES 261
there will still remain a wondorfiilly rich aiKJ vaii.-.l }i,,ia
to have been carried, by the various natural means above
indicated, over 900 miles of ocean, more especially as the
large proportion of species identical with those of Europe
shows that their introduction has been comparatively recent,
and that it is, probably (as in the case of the birds) still
going on. We may therefore feel sure that we have lierc
by no means reached the limit of distance to which plants
can be conveyed by natural means across the ocean ; and
this conclusion wilt be of great value to us in investigatini,^
other cases where the evidence at our command is less
complete, and the indications of origin more obscure or
conflictino-.
o
Of the forty species which are considered to be peculiai-
to the islands, all are allied to European plants except six.
whose nearest affinities are in the Canaries or Madeira.
Two of the Compositse are considered to be distinct genera,
but in this order generic divisions rest on slight technical
distinctions ; and the Campanula vidalii is very distinct
from any other known species. With these exceptions,
most of the peculiar Azorean species are 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 islands
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 some lowering of temperature ; while in such a
warm latitude and surrounded with sea, there would always
be many sunny and sheltered spots in which even tender
plants might flourish.
Important Deduction from, the Fcculiaritics of the Axor-
ean Fauna and Flora.— T\\exQ is one conclusion to be
drawn from the ahnost wholly European cliaracter of tlie
Azorean fauna and ilora which deserves special attention,
namel}^ that the peopling of remote islands is not due
so much to ordinary or normal, as to extraordinary and
exceptional cau.ses. These islands lie in the course of tlic
south-westerly return trades and also of tlie Gulf Stream,
and we sliould therefore naturally expect that American
birds, insects, and |)lants would preponderate if they were
262 ISLA^s'D LIFE
conveyed by the regular winds and currents., which are
both such as to prevent European species from reaching
the islands. 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 favourable situation of the coasts of Europe and
North Africa, that the presence of a fauna and flora so
decidedly European is to be traced.
Tlie other North Atlantic Islands — Madeira, the Can-
aries, and the Cape de Verdes — present analogous phen-
omena 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 Gt'ogrcvphical Dis-
trUmtion of Animals (Vol. I. pp. 208-215) ; and as we are
now dealing with what may be termed typical examples
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 coial-sand consolidated into rock.
They are situated in 32° N. Lat., about 700 miles from
North Carolina, and somewhat farther from the Bahama
Islands, and are thus rather more favourably placed for
receiving immigrants from America and its islands than the
Azores are with respect to Europe. There are about 100
islands and islets in all, but their total area does not ex-
ceed 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 that the islands have once been more extensive
and probably included the whole area now occupied by
shoals and reefs.^ Immediately beyond these reefs, how-
"^ Nature, Vol. YI. i>. 262, "Recent Observations in the Bermudas, " by
Mr. J. Matthew Jones.
CHAP. XII
BERMUDA
ever, extends a very deep ocean, while about 4.")<i miU'.s
distant in a south-east direction, tlie deei)Ost part of ihv
North Atlantic is reached, where somidings of .S,S25 and
MAP OF nrRMl'DA AND THE AMHRICAN COAST.
XoTE.— The light tint indicates sea less than 1,000 fathoms (fcep
The dark tint ,, ,, more tlian 1,000 I'athoms deeji,
Tlie figures show the depth in fathoms.
3,87o fathoms have been obtained. It is clear theivfore
that these islands are typically oceanic.
Soundings were taken by the ChaJIciKjr,- in fuur differ-
26i I8LAXD LIFE
TAUT II
ent directions around Bermuda, and always showed a rapid
deepening of the sea to about 2,500 fathoms. This was
so remarkable, that in his reports to the Admiralty, Captain
Nares spoke of Bermuda as " a solitary peak rising abruptly
fVom a base only 120 miles in diameter;" and in another
place as " an isolated peak rising abruptly from a very
small base." These expressions show that Bermuda is
looked upon as a typical example of an " oceanic peak " ;
and on examining the series of official reports of the
Challenger soundings, I can find no similar case, although
some coasts, both of continents and islands, descend more
abruptly. In order to show, therefore, what is the real
character of this peak, I have drawn a section of it on a
BERMUDA
< 55 MILES ^eia MILES-X 46 MILES.- >
SECTION OF BERMUDA AND ADJACENT SEA BOTTOM.
The figures show the depth iu fathoms at fifty-five miles north and forty-six miles soiitli
of the islands respectively.
true scale from the soundings taken in a north and south
direction where the descent is steepest. It will be seen
that the slope is on both sides very easy, being 1 in 16 on
the south, 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 limestone rock,
sometimes soft and friable, but often very hard and even
crystalline. It consists of beds which sometimes dip as
much as 30°, and which also show great contortions, so that
at first sight the islands appear to exhibit on a small scale the
phenomena of a disturbed Palseozoic district. It has however
lonsf been known that these rocks are all due to the wind,
CHAP. XII BERMUDA 2r,5
wliich blows up tho fine calcareous sand, the product of tin-
disintegration of coral, shells, serpuke, and other ors:,^anisnls,
forming sand-hills forty and fifty feet high, wliich move
gradually along, overwhelming the lower tracts of land be-
hind them. These are consolidated by the percolation of
rain-water, which dissolves some of the lime from the more
porous tracts and deposits it lower down, filHng every
fissure wdth stalagmite.
The Red Clay of Bermuda, — Besides the calcareous
rocks there is found in many parts of the islands a layer of
red earth or clay, containing about thirty per cent, of
oxide of iron. This very closely resembles, botli in colour
and chemical composition, the red clay of the ocean floor,
found widely spread in the Atlantic at depths of from 2,30<i
to 3,150 fathoms, and occurring abundantly all round
Bermuda. It appears, therefore, at first sight, as if the
ocean bed itself has been here raised to the surface, and a
portion of its covering of red clay preserved ; and this is
the view adopted by Mr. Jones in his paper on the " Botany
of Bermuda." He says, after giving the analysis: "This
analysis tends to convince us that the deep chocolate-
coloured red clay of the islands found in the lower levels,
and from hiii,h-water mark some distance into the sea,
originally came from the ocean floor, and that Avhen by
volcanic agency the Bermuda column was raiseil from the
depths of the sea, its summit, most jDrobably 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 sufBcient evidence to
prove its identity \\i(\\ that now lying contiguous to the
base of the Bermuda column." But in liis Guide to
Bermuda Mr. Jones tells us that this same red earth has
been found, two feet thick, under coral rock at a deptli of
forty-two feet below low-water mark, and that it " restetl
on a bed of compact calcareous sandstone." Now it is
quite certain that this " calcareous sandstone " was never
formed at the bottom of the deep ocean 700 miles from
land ; and the occurrence of the red earth at ditlercnt
levels upon coralline sand rock is therefore more probably
due to some process of decomposition of the rock itself,
266 ISLAND LIFE part ii
or of the minute organisms which abound in the
blown sand/
Zoology of Bermuda. — As might be expected from their
extreme isolation, these islands possess no indigenous
terrestrial mammalia, frogs, or snakes.^ There is however
one lizard, whi(;h Professor Cope considers to be distinct
from any American species, and which he has named
Plesticdon {Eumcccs) longirostiis. It is said to be most
nearty allied to Eumcccs quinquelinecdus of the south-
eastern States, from which it differs in having nearly ten
more rows of scales, the tail thicker, and the muzzle longer.
In colour 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 being the only vertebrate animal
which exhibits any peculiarity.
Birch. — Notwithstanding its small size, low altitude and
1 "The late Sir C. AVyville Thomson was of opinion that the 'red
earth ' which largely forms the soil of Bermuda had an organic origin, as
well as the ' red clay ' which the Challenger discovered in all the greater
depths of the ocean basins. He regarded the red earth and red clay as an
ash left behind after the gradual removal of the lime by water charged with
carbonic acid. This ash he regarded as a constituent part of the shells of
Foraminifera, skeletons of Corals, and ]\Iolluses, [vide Voyage of the
Challenger, Atlantic, Yol. I. p. 316]. This theory does not seem to be in
any way tenable. Analysis of carefully selected shells of Foraminifera,
Heteropods, and Pteropods, did not show the slightest trace of alumina,
and none has as yet been discovered in coral skeletons. It is most
probable that a large part of the clayey matter found in red clay and the
red earth of Bermuda is derived froni the disintegration of pumice, which
is continually found floating on the surface of the sea. [See ^lurray, '-'On
the Distribution of Volcanic Debris Over the Floor of the Ocean ; " Proc.
Roy. See. Edin. Yol. IX. pp. 247-261. 1876-1877.] The naturalists of the
Challenger found it among the floating masses of gulf weed, and it is
frequently picked up on the reefs of Bermuda and other coral islands.
The red earth contains a good many fragments of magnetite, augite, felspar,
and glassy fragments, and when a large cjuantity of the rock of Bermuda
is dissolved away with acid, a small number of fragments are also met with.
These mineral particles most probably came originally from the pumice
which had been cast up on the island for long ages (for it is known that
these minerals are present in pumice), although possibly some of them may
have come from the volcanic rock, which is believed to form the nucleus
of the island." The Voyage of H. M.S. CAay/c/jr/c/-, Xarrative of the Cruise.
Yol. I. 1885, pp. 141—142.
2 Four bats occur rarely, two being X. American, and two West Indian
Species. The Bermuda Islands, by Angelo . Heilprin, Philadelphia.
IBSP.
CHAP. XII BER^IUDA 287
remote i)Osifion, a great number of birds visit Bci rnud.i
amiiially, some in large numbers, others only as accidental
stragglers. Altogether, over 180 species have been
recorded, rather more than half being "wading and swim-
ming birds, whose presence is not so much to be wondered
at as they are great wanderers; while about eighty-five
are land birds, many of which Avould hardly be supposed
capable of flying so great a distance. Of the 180 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
jiearly half these appear to come every year.
There are only eleven species which are permanent
residents on the island — eight land, and three water birds,
and of these one has been almost certainly introduced.
These resident birds are as follows : —
1. Galcoscoptcs carolincmi^. (The Catl)ir(l.) Migrates aloiii,' tlie oa.st
coast of the T'liite'l States.
2. Sialia sialis. (The Bhie liinl.) ]\Iigrate.s along the east coast.
3. Virco novcehoracensis. (The Wliite-eyed green Tit.) Migrates along
the east coast.
4. Parser domcsticus. (The English 8j»avro\v.) ? Introducfd.
5. Corviis americanus. (The Anieiican Crow.) ('oninion over all
North America.
G. Cardinalis vrrginiann.-i. ('J'lie r'anlinal hird.) Migrates fi'om
Carolina southward.
7. Chamcepdiapassci-ina. (The ground Dove.) Louisiana, ^\'. Indies,
and Mexico.
8. Orfyx virrfinianus. (The American Quail.) Xew England to
Florida.
9. Ardcaltrrodias. (The Creat Blue Heron.) All Xorth America.
10. fiaUiimla galrata. (The Florida (Jallinuh'.) Temperate and
tropical North Amerii a.
11. Phdciontlavirostris. (The Tropic Binl.)
It will be seen that these are all very common
North American birds, and most of them are constant
visitors from the mainland, so that howi-xcr lt>ng they
may have inhabited the islands there has been no chance
for them to have acquired any distincti\'e characters
owing to the want of is(^lation.
Among the most regular visitants which are not resident,
are the connnon N. American Idngfisher {Ccrylr alci/on),
ISLAND LIFE part it
the night-hawk {Chordeiles virginianus), the wood wagtail
(Smrus novcchoracensis), the snow-bunting {FUdro'pliancii
nivalis), and the wide-ranging rice-bird {Dolichonyx
oryzivora), all very common and widespread in North
America.
Comjmrison of the Bird-faunas of Bermuda and the
Azores. — The bird-fanna of Bermuda thus differs from that
of the Azores, in the much smaller number of resident species,
and the presence of several regular migrants. This is due,
first, to the small area and little varied surface of these
islands, as well as to their limited flora and small supply
of insects not affording conditions 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 larger number of its birds to be migratory than in
Europe. The Northern United States and Canada, wath
a sunny climate, luxuriant vegetation, and abundant insect-
life daring the summer, supply food and shelter to an im-
mense 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, others as far as the West
Indies, Mexico, or even to Guatemala and South America.
Every spring and autumn, therefore a vast multitude of
birds, belonging to more than a hundred distinct species,
migrate northward or southward in Eastern America. A
large proportion of these pass along the Atlantic coast, and
it has been observed that many of them fly some distance
out to sea, passing straight across bays from headland to
headland by the shortest route.
Now as the time of these migrations is the season of
storms, especially the autumnal one, which nearly coincides
wdth the hurricanes of the West Indies and the northerly
gales of the coast of America, the migrating birds are very
liable to be carried 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 north
w^esterly gale, they are rapidly driven sea-ward. The great
majority no doubt perish, but some reach the Bermudas
CHAP, xit IBERMIJDA 260
and form one of its most striking autumnal features. In
October, Mv. Jones tells us, the sportsman enjoys uum-
shooting than at any other time. The violent revolving
gales, Avliicli occur almost weekly, bring numbers of birds
of many species from the American continent, the cli tie rent
members of the duck tribe forming no inconsiderable por-
tion 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 (Turdus migratorms), the yell<jw-
rumped warbler {Dcmlrceca coronata), the pine warbler
(Daidroica innus), the wood wagtail {Siiirm noiwhoracmsis),
the summer red bird (Pyranga cvdiva), the snow-bunting
(Flcdroplirtncs nivalis), the red-poll (^■Efjiotlws linarius),
the king bird {Tyranwus carolinensis), and many others.
It is no doubt in consequence of this repeated immigration
that none of the Bermuda birds have ac(][uired any special
peculiarity 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 wheatear {Saxicola cenanthe), whicli visits Iceland and
Lapland and sometimes the northern United States ; the
skylark (Alattda arveusis), but this was probably an im-
ported bird or an escape from some ship ; the land-rail
{Crc:c pratcnsiii), which also wanders to Greenland and the
United States; and the common snipe {Scolopac (jallincujo),
which occurs not uufrequently in Greenland but has not
yet been noticed in North America. It is however so like
the American snipe {S. wihoni), that a straggler might
easily be overlooked.
Two small bats of N. American species also occasionally
reach the island, while two others from the West Indies
have more rarely occurred, and these are the only wild
mammalia except rats and mice.
Inaecf.s of Bermuda. — Insects appear to he \rry scarce ;
but it is evident from the lists given by Mr. Jones, and
more recently by Professor Heilprin. that oidy the more
conspicuous S2)ecies have been yet collected. Tin.'
'Sf coin-
270
ISLAND LIFE
PART II
prise nineteen beetles, eleven bees and wasps, twenty-six
butterflies and moths, nine flies, and the same number of
Hemiptera, Orthoptera, and Neuroptera respectively. All
appear to be common North American or West Indian
species ; but until some comi3etent entomological collector
visits the islands it is impossible to say whether there are
or are not any peculiar species.^
Land MoUiisca. — The land-shells of the Bermudas are
somewhat more interesting, as they appear to be the only
group of animals except reptiles in which there are any
peculiar species. The following list was kindly furnished
me by Mr. Thomas Bland of iNew York, who has made a
special study of the terrestrial molluscs of the West Indian
Islands, from which those of the Bermudas have undoubt-
edly been derived. The nomenclature has been corrected
in accordance with the list given in Professor Heilprin's
work on the islands. The species wliich are peculiar to
the islands are indicated by italics.
Llst of the Land-8hi:ll.s of Ukumuda.
1. Siiccinca fulgeiis. (Lea.) ...
2. ,, Bermudeiisis. (Pfeitter. ).
3. ., inargarita. (PIV. )
4. Fcecilo'~:oiiitcsBcnivudeiisis.{Vh\) .
5. ,, circumfirnicUas (Redliekl.
6. ,, discrcpans. (Plr. ).
7. ,, Reinianus. (PtV. )...
8. Patula (Thysanophora) liypolepta.
9. ., vortex. (Pfv.) "...
10. Helix mierodonta. (Desli.)
11. ., appressa. (Say.)
Also ill Cuba.
.. Barbadoco (f)
, , Haiti.
A peculiar form, wliich, according
to Mr. Biiiney, "cannot be
placed in any recognised genus. "
A larger sub-fossil variety also
occurs, named H. Kelsoni, by
Mr. Bland, and which appears
sufficiently distinct to be classed
as another species.
iShuttleworth.)
Southern Florida and ^^'est Indies.
Bahama Islands, Florida, Texas.
Virginia and adjacent states ; per-
haps introduced into Bermuda.
^ Fourteen species of Spider.^ were collected by Prof. A. Heilprin, all
American or cosmopolitian species except one, Lycosa atlantka, which Dr.
]\rarx of Washington describes as new and as peculiar to the islands.
(Heilprin's The B'r,nudas, p. 93.)
CHAP, xii BERMUDA 1:71
12. Helix pulclK'Ila. iMiill.^ Europe ; very close to //. //<i/ti<^t.
(Say) of the United States.
Introduecd into Bi-rnniila (?)
13. ,, ventricosa. ''Drap. ' ... ... Azores, Canary Lslands, and South
Europe.
II. Bulimulus nitidulus. (Pfr. ) ... Cuba, Haiti, &c.
15. Stenogyra octona. (Ch.) ... ... West Indies and Souili Aniuriea.
16. Stenogyra decollata (Linn.) ...A South European species.
Introduced.
17. Ccecilianella acicula. (Miill. ' ... Florida, Xew Jer.sey, ami Europe.
18. Pupa pellueida." (Pfr.) West Indies, and Yucatan.
19. ,, Barbadensis. (Pfr.) Barbadoes(?)
■JO. ,, Jamaicensis. (C B. Ad.) ... Jamaica.
21. Helicina convexa. (Pfr.) ...Barbuda.'
Mr. Bland itidicates only four species as certainly peculiar
to Bermuda, and another sub-fo.ssil species; Avhile one or
two of the remainder are indicated as doubtfully identical
with those of other countries. We have thus about one-
lifth of the land-shells peculiar, while almost all tlie
other productions of the islands are identical with those of
the adjacent continent and islands. This corresponds,
however, with what occurs generally in isUinds 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 (»ne-
twentieth ; while the land-shells have about half the
species peculiar. This difference is well explained by
the much greater difficulty of transmission ovi-r wid<'
seas, in the case of land-shells, than of any other ter-
restrial organisms. It thus haiDpens that Avhen a species
has once been conveyed it may remain isolated for un-
known ages, and has time to become modified l)y local
conditions unchecked by tlie introduction of otlici- in-
dividuals of the original type.
Flora of Bermuda. — Unfortunately no good account of
the plants of these islands has yet been published. Mr.
' ^h\ Theo. D. A. Corkerell informs me that there are two .»lugs in
Bermuda of which sy)ecinienscxi.st in the British Musrum. — Jmalia (/injiitt-'i
Drap. common in Europe, and ^lyrivUiiuiu: ciinvpL'siris of tlie Unitcil States.
Both may therefore liave been introduced by liuman agency. Also
Vaqinulu.s Mordclc var. schivcl>/ic which .seems to be a variety of a Mexican
species ; perhaps im])orted.
272 ISLAND LIFE
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 agricultural or garden seeds,
and the really indigenous j^lants, in one undistinguished
series. It apjDears too, that the late Governor, Major-
General Lefroy, " has sown and distributed throughout 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 future years to distinguish the indigenous from
the introduced vegetation.
From the researches of Dr. Rein and Mr. Moseley there
appear to be about 250 flowering plants in a wild state,
and of these Mr. Moseley thinks less than half are indige-
nous. The majority are tropical and West Indian, while
others are common to the Southern 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 us that the
currents bring numberless objects animate and inanimate
from the Carribean Sea, including the seeds of trees,
shrubs, and other plants, which are continually cast
ashore and sometimes vegetate. The soap-berry tree
(Scqj inches saponaria) has been actually observed to
originate in this way.
The only species of flowering plant peculiar to Bermuda
is Car ex Bermudiana (Hemsley), which is said to be
allied to a species found only in St. Helena ; but there
are some local forms of continental species, among
which are Sisyrinchmm Bcrmudionnm and a variety of
Rhus toxicodendron. There are, however, two ferns —
an Adiantum and a Nephrodium, which are unknown
from any other locality. The juniper, which is so
conspicuous a feature of the islands, is said to be a
West Indiau species {Juniperiii^ larhadcnsis) found in
Jamaica and the Bahamas, not the North American red
CHAP, xri BEinrUDA 073
cedar; but there seems to bo still .some doubt ;d)nut this
common plant.
Mr. Moseley, who visited Bermnda in tlie Ch(dJ>nii. >\
has well explained the probable origin of the vegotation.
The large number of West Indian plants is no doubt due
to the Gulf Stream and constant surface drift of warm
water in this direction, while others have been brought l)y
the annual cyclones which sweep over the intervening
ocean. The great nund^er of American migratory h'mh.
including large flocks of the American golden plover, witli
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 surprising that almost
all the species should be unchanged owing to the frequent
intercrossing 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 clue to the solution of
many difficult problems in their geographical distribution.
Concluding Bcmarks. — The t^vo groups of islands we
have now been considering furnish us with some most in-
structive facts as to the power of many groups of organisms
to pass over from 700 to 900 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 re-
gards birds, migratory habits and the liability to be cauglit
by violent storms are the conditions which determine the
island -population. In both islands the land-birds are al-
most 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 propor-
tion as the migratory habits and prevalence of storms
afford more efficient means for their introduction.
^ " Notes on the Vegetation of Bermuda, " by H. N. Moselev. .hmnud
of the Linncan Society, Vol. XIY., Botanij, p. 317.)
T
274 ISLAND LIFE
We find also, that these great distances do not prevent
the immigration of some insects of most of the orders, and
especially of a considerable number and variety of beetles ;
while even land-shells are fairly represented in both islands,
the large joro^Dortion 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 Avhich 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 islands, but were either not
suited to the climate and other physical conditions, or did
not find the insects necessary to their fertilisation, and
were therefore unable to maintain themselves.
If now we consider the extreme remoteness and isolation
of these islands, their small area and comparatively recent
orioin, and that, notwithstandino- all these disadvantao-es,
they have acquired a very considerable and varied flora
and fauna, we shall, I tliink, be convinced, tliat with a
larger area and greater antiquity, 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 importance in
those cases where the evidence as to the exact origin of
the fauna and flora of an island is less clear and satisfactory
than in the case of the Azores and Bermuda.
CHAPTER Xlir
THE GALAPAGOS ISLANDS
Position and Pliy.-^ical Features — AbscMice of Iiuligonou? jMammalia an<l
Amphibia — Keptik-s — Birds — Insects and Land-Shells — The Keelini,'
Ishind:^ as Ilhistrating the Manner in wliich Oceanie Lshmdsare Peopk'd
— Flora of the Galapagos —Origin of the Flora of the Galaparos — Con-
eluding Remark';.
The Galapagos differ in many important respects from the
islands we have examined in our last chapter, and the
differences are such as to have aftected the whole character
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 that a large portion of tlieir
surfiice consists of barren lava-iields. They are considerably
less distant from a continent than either the Azores or
Bermuda, being about 600 miles from the west coast of
South America and a little more than 700 from Veragua,
with the small Cocos Islands intervening; and they arc
situated on the equator instead of being in the north tem-
perate zone. They stand upon a deeply submerged bank,
the 1,000 fathom line encircling all the more ini])ortani
islands at a few miles distance, whence there appears to be
a comparatively steep descent all round to the averagi'
depth of that portion of the Pacific, between 2,000 and
3,000 fathoms.
r2
276
ISLAND LIFE
PART II
The whole group occupies a space of nbout 300 by 20U
miles. It consists of five large and twelve sniall islands ;
the largest (Albemarle Island) being about eighty miles
MAP OF THE GALAPAGOS AKD ADJACENT COASTS OF SOUTH AMERICA.
The light tint shows where the sea is less than 1,000 fathoms deep.
The figures show the depth in fathoms.
long and of very irregular shape, while the four next in
importance — Chatham, Indefatigable, James, and Nar-
borough Islands, are each about twenty-five or thirty miles
(HA I'. XIII
THE GALAPAGOS ISLAXDS
•277
long, and of a rounded or elongate form. The whole are
entirely volcanic, and in the western islands there are
numerous active volcanoes. Unlike the other groups of
islands we have been considering, these are situated in a
MAI* OF THE GALA1'AC;<
The liglit lint sliows a (Icptli of less than 1,000 fatlionis.
Tlie figures show the depth in lathonis.
comparatively calm sea, wht-re storm.s are (»f rare occur-
rence and even strong winds almost unknown. They arc
traversed by ocean currents which are strong and constaut,
Mowing towards tlie north-west from the coast of Peru ;
278 ISLAND LIFE
and these physical conditions have had a powerful
influence on the animal and vegetable forms by which the
islands are now inhabited. The Galapagos have also,
during three centuries, been frequently visited by
Europeans, and were long a favourite resort of buccaneers
and traders, who found an ample supply of food in the
large tortoises which abound there ; and to these visits we
may perhaps trace the introduction of some animals whose
presence it is otherwise diflicult to account for. The
vegetation is generally scanty, but still ampl}^ sufficient for
the supi3ort of a considerable amount of animal life, as
shown by the cattle, horses, asses, goats, pigs, dogs, and
cats, which now run Avild in some of the islands.
Ahscncc of IncUffcnous ^[ammaJia and Amphihia. — As in
all other oceanic islands, we find here no truly indigenous
mammalia, for though there is a mouse of the American
genus Hesperomys, which differs somewhat from any known
species, we can hardly consider this to be indigenous ; first,
because these creatures have been little studied in South
America, and there may yet be many undescribed species,
and in the second place because even had it been intro-
duced by some European or native vessel, there is ample
time in two or three hundred years for the very different
conditions to have established a marked diversity in the
characters of the 'species. This is the more probable
because there is also a true rat of the Old World genus
Mus, which is said to differ slightly from any known
species ; and as this genus is not a native of the American
continents we are sure that it must have been recentl}'
introduced into the Galapagos. There can be little doubt
therefore that the islands are completely destitute of truly
indigenous mammalia ; and frogs and toads, the only
tropical representatives of the Ami^hibia, are equally
unknown.
Reptiles. — Eeptiles, however, which at first siglit appear
as unsuited as mammals to pass over a wide expanse of
ocean, abound in. the Galapagos, though the species are not
very numerous. They consist of land-tortoises, lizards and
snakes. The tortoises consist of two peculiar species,
Testuclo micro])hyes, found in most of the islands, and T.
CHAi\ xiii THE GALAPAGOS ISLANDS 27it
ahiiigdonii recently discovered on Abingdon Island, as well
as one extinct species, T. ephipidnm, found on Indefatigable
Island. These are all of very large size, like tlie gigantic
tortoises of the Mascarenc Islands, from which, however,
they differ in structural characters ; and Dr. Oiiiithor
believes that they have been originally derived fn»iii tin-
American continent.^ Considering the well known tenacity
of life of these animals, and the large nund)L'r of allied
forms which have aquatic or sub-aquatic liabits, it is nut
a very extravagant supposition that some ancestral form,
carried out to sea by a flood, was once or twice safely
drifted as far as the Galapagos, and thus originated the
races which now inhabit them.
The lizards are five in number ; a peculiar species of
gecko, Phyllodactylus galapagcnsis, and four species of
the American family Iguanido?. Two of these are distinct
species of the genus Tropidurus, the other two being large,
and so very distinct as to be classed in peculiar genera.
One of these is aquatic and found in all the islands, swim-
ming 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 last were originally
described as AmhlyrhyncMts cristatus by Mr. Bell, and
A. suhcristatus by Gray ; they were afterwards placed in
two other genera Trachycephalus and Oreocephalus (scr
Brit. Mus. Catalogue of Lizards), while in a recent paper
by Dr. Stcindachner, the marine species is again chissed as
Amblyrhynchus, wdiile the terrestrial form is placed in
another genus Conolophus, both genera being peculiar t<»
the Galapagos.
How these lizards reached the islands we cannot tell.
The fact that they all belong to American genera or
families indicates their derivation from that continent,
while their being all distinct species is a proof that their
arrival took place at a remote 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.
1 Gujaafk Load Tortoises Lahuj a,hl Krllnrt in th, Collcdion of the
Briiisk Muiicum. By A. C. L. 0. Giintlu-r. F.K.S. 1877.
280 ISLAND LIFE
since they are found in a considerable number of islands
which possess no mammals nor any other land reptiles ;
but what 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 lizards. 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 climates
and especially during earthquakes. To some such accident
we may perhaps attribute the presence of these creatures
in the Galapagos, and that it is a very rare one is indicated
by 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 interest not exceeded by any other group.
About seventy species of birds have now been obtained on
these islands, and of these forty-one are peculiar to them.
But all the species found elsewhere, except one, belong to
tlie aquatic tribes or the waders which are pre-eminently
Avanderers, yet even of these eight are peculiar. The true
land -birds are forty-two in number, and all but one are
entirely confined to the Galapagos ; while three-fourths
of them present such peculiarities that they are classed in
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 southern continents — is the only land-bird
identical with those of the mainland. 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,
to which are added nine species collected in 1888 and
CHAP. XIII
THE GALAPAGOS ISLANDS
281
described by Mr. Ridgway in the ProceaUiujs i,f (he
U.S. National Miiscuni (XII. p. 101) and some a(l«liti.)ii;d
species obtained in 1889.
TniDITtA
1. Xesomimus trifasciatus
2. .. iiielanotus
3. .. parvulus
4. .. inacdonalJi (Ritlg. )
5. .. personatus (Ridg. )
I This and llic two allit.-d .sp.'c.-it'.s
- are rolatod to a rciuviau bird
' Mi inns JonqicKUfhi.a.
i3. Dendrcuca aiiieol;
MNIOTILTId;.
( Closely allied to the widc-raii}
[ ing Z). (csiiva.
ProKHc coiicolor
HiRUXDINID.E.
f Allii'd 1(1 r. purpui-ia of XurtI:
I ami .South America.
8. Certhidea olivacea ...
0. " fusca
lu. " cinerascons
CCEKEBIDJ;.
/ A ]»iMuliar giMiu> allied to th<
I Andean genu- L'oniroj?truni.
Frixgillid.*:.
11. Geospiza niagnirostri.s
12. .. strenua
13. ., diibia
14. .. Ibrtis
15. .. nebulosa
16. .. fnliginosa
17. .. parvula
18. .. dentirostris
19. .. eonirostris (Ridg. ) ...
20. .. media (Ridg.)
21. ., difficilis (Sharpe) ...
22. (.'aetornis scanden.s
23. . , a.ssimili.s
24. ., abingdoni
25. ,, pallida
26. .. brevirostris (Ridg.)
27. ., hypolouca(Ridg.) ...
28. r'iimarhyiiehus p.sittaculu.s
29. ,, erassirostris ...
30. ,, varicgatus
31. ., prosthemela.s ...
32. ., habeli
33. ., townsendi (Ridg.
34. ,, pauper (Ridg. )
A distinet genus, but allied toth<
South Ameriean genus Guiraca.
A genus ;illied lo the la.^^t.
A very ]ic(uliai- gruus allied to
XeorlivnehuN of the we.st eoast
of I'.'rii.
282
ISLAND LIFE
35. Dolichonyx oryzivoru.s
36. Pyrocephalus nanus
37. P. minimus (Ridg. "*
38. Myiarelius magnirostris . .
30. Zenaida galapagensis
40. Buteo galapagensi-s ...
4L Asio galapagen.sis
42. Strix ])unctati.ssima
ICTERID^.
Ranges from Canada to Para-
guay.
Tyranxid^.
Allied to P. rubincus of Ecua-
dor.
Allied to AVest Indian species.
COLUMBID.i:.
/ A i)eculiar species of a S.
[ American genus.
Falcoxid.e.
A buzzard of peculiar coloration.
STRIGID.E.
) Hardly distinct from the wide-
) si)read A. hrachyoius.
Allied to S. Jlammca Lut tiuitc
distinct.
We have here every gradation uf difference from perfect
identity with the continental species to genera so distinct
that it is difficult to determine with Avhat 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, migration to the islands. The excessively
abundant rice-bird, which breeds in Canada and swarms
over the whole United States, migrating to the West
Indies and South America, visiting the distant 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, w^e have the almost cosmopolite
short-eared owl {Asio Irachyotus), which ranges from
China to Ireland, and from Greenland to the Straits of
Magellan, and of this the Galapagos bird is probably only
one of the numerous varieties. The little wood warbler
{Dcnchara aiorcola) is closely allied to a species which
cHAi'. XIII THE GALAPAGOS ISLANDS 263
ranges over the whole of North America and as far south
as New Grenada. It has also been occasionally met witli
in Bermuda, an indication that it has considerable powers
(»f ilight and endurance. The more distinct .y)ccifs — iis the
tyrant fly-catchers (Pyrocephalus and Myiarchus), the
giound-dove (Zenaida), and the buzzard (Buteo), are all
allied to non-migratory species peculiar to tropical America,
and of a more restricted range ; wdiile the distinct rjcnrni
are allied to South American groups of thrushes, 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 ancestral forms of these
birds which, owing to some exceptional causes, reached the
Galapagos, have thus remained uninfluenced by later
migrations, and have, in consequence, been developed into
a variety of distinct types adapted to the peculiar con-
ditions of existence under which they have been placed.
Sometimes the different species thus formed are confined
to one or two of the islands only, as the tliree species of
Certhidea, which are divided between the islands but do
not appear ever to occur together. Nesomimus ^Kirvulas is
confined to Albemarle Island, and X. trifasciatus to Charles
Island; Oadornis 7J«//iV?« to Indefatigable Island, C.
hrevirostris to Chatham Island, and C. ahingdoni to
Abingdon Island.
Now all these phenomena are strictly consistent witli
the theory of the peopling of the islands by accidental
migrations, if we only allow them to have existed for a
sufficiently long period ; and the fact that volcanic action
has ceased on many of the islands, as well as their great
extent, would certainly indicate a considerable anti(|uity.
The great difference presented by the birds of these
islands as compared with those of the ec[ually remote
Azores and Bermudas, is sufficiently explained by the
difference of climatal conditions. At the Galapagos there
are none of those periodic storms, gales, and hurricanes
which prevail in the North Atlantic, and which every
year carry some straggling birds of Europe or North
America to the former islands ; while, at the same time,
the majority of the tropical American birds are non-
284 ISLAXD LIFE
migratory, and thus afford none of the opportunities
jDresented 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 forty
species belonging to thirty-two genera and nineteen
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-Avide groups. The
Carabid^ and the Heteromera are the most abundant
groups, the former furnishing six and the latter nine
species.^
^ The following list of the beetles yet known from the Galapagos shows
their scanty proportions and accidental character ; the fort}' species be-
longing to thirty-three genera and eighteen families. It is taken from
^Ir. AVaterhonse's enumeration in the Proeccdinqfi of the Zoological S'ocictj/
for 1877 (p. 81), with a few additions collected by the IJ. S. Fish Com-
mission Steamer Albatross, ami published bv the t'. S. National ^Museum
in 1889.
Cauabid.e. Malacodekms,
Feronia calathoides. Ablechrus darwinii.
,, insularis, ("'orynetes rutipes.
,, galapagoensis. Bostrichus unciniatus.
Amblygnathus obscuricornis. TetrajM-iocerca sp.
Solenophorus galapagoensis. Lamei,licoi:xes.
Xotaphus galapagoensis. Co^jris lugubris.
Dytiscid^. Oryctes galapagoensis.
Euuectes occidentalis. Elatekid^.
Acilius incisus. Physorhinus galapagoensi-.
Copelatus galapagoensis. Heteromera.
Pali'ICOrxes. AUecula n. s.
Tropisternus lateralis. Stomion helopoides.
Philhydrus sp. . , Isevigatum.
Staphylinidj^. Ammophorus obscurus.
Creophilus villosus. . . cooksoni.
Xecrophaga. .. bifoveatus.
Acribis serrativentris. i'edonceccs galapagoensi''.
Phalacrus darwinii. ., pubescens.
Dermestes vulpinus. Plialeria manirata.
CHAi'. XIII THE rULAPAGOS ISLANDS 2So
Tiie land-sliells are not abundant — about twenty in all.
niost of tlit'm peculiar species, but not otherwise remark-
able. The observation of Captain Collnet, quoted by Mr.
Darwin in his Journal, that drift-wood, Ixiniboos, canes,
and tlie nuts of a palm, are often waslied on tlie south-
eastern shores of the islands, furnishes an excellent chie
to the manner in which many of the insects and land-
shells may have reached the Galapagos. Whirlwinds also
have been known to carry quantities of leaves and other
vegetable delris to great heights in the air, and tliese
might be tiien carried away by strong upper currents and
dropped at great distances, and with them small insects
and mollusca, or their eggs. We must also remember
that volcanic islands are subject to subsidence as well as
elevation ; and it is cpiite possible that during the long
period the Galapagos have existed some islands may have
intervened between them and the coast, and have served
as stepping-stones by which the passage to them of
various organisms would be greatly facilitated. Sunken
banks, the relics of sucli islands, are known to exist in
many parts of the ocean, and countless others, no doubt,
remain undiscovered.
Tlic Keeling Islands as Illustrating the Manner in which
Oceanic Islands are Peopled. — That such causes as have
been here adduced are those by which oceanic islands have
been peopled, is further shown by the condition of equally
remote islands which we know are of comparatively recent
origin. Such 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 veofetation. These islands were visited bv Mi-.
CURCULIOXIDJE. PlIYT(tPHA(;A
Otioihynclius cuneifonuip. Diabrotica liinl»ata.
Anehoiius galapagoensis. Docema rcalapagoonsis,
LoNGiroRXiA. Longitarsus lunatu.s.
Mallodou sp. SECUHirAi.PEs.
Kburia amabilis. Scymuns galapa^oensis.
A NTHUIBID.I-:.
Onui^^cus variegatn?
286 ISLAND LIFE
Darwin, and tlieir natural history carefully examined.
The only mammals are rats, brought by a wrecked vessel
and said by Mr. Waterhouse to be common English rats,
" but smaller and more brightly coloured ; " so that we
have here an illustration of how soon a difference of race
is established under a constant and uniform difterence of
conditions. There are no true land-birds, but there are
snipes and rails, both apparently common Malayan
species. Reptiles are represented by one small lizard,
but no account of this is given in the Zoology of the
Voyage of the Beagle, and we may therefore conclude
that it was an introduced species. Of insects, careful
collecting 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
multiply, in order to give these islands a fauna and flora
equal to that of the Bermudas. Of wild plants there
were only twenty species, belonging to nineteen genera and
to no less than sixteen natural families, while all were
common tropical shore plants.^ These islands are thus
evidently stocked by waifs and strays brought by the
Avinds and waves; but their scanty vegetation is mainly
due to unfavourable conditions — the barren coral rock and
sand, of which they are wholly composed, together with
exposure to sea-air, being suitable to a very limited
number of species which soon monopolise the surface.
With more variety of soil and aspect a greater variety of
plants would establish themselves, and these would favour
the preservation and increase of more insects, birds, and
^ Mr. H. 0. Forbes, who visited these islands in 1878, increased the
number of wild plants to thii'ty-six, and these belonged to twenty-six
natural orders.
cuAV. XIII THE GALAPAGOS ISLANDS 287
other animals, as we find to be the case in many small
and remote islands.^
Flora of the Galapagos. — The plants of these islands are
so much more numerous than the known animals, even
including the insects, they have been so carefully studied
by eminent botanists, and their relations throw so much
light on the past history of the group, that no apology is
needed for giving a brief outline of the peculiarities and
affinities of the flora. The statements we shall make on
this subject will be taken from the Memoir of Sir Jose})h
Hooker in the Linnccan Transactions for 1851, founded
on Mr. Darwin's collections, and a later paper by N. J.
Andersson in the lAnncca of 18(31, embodying more recent
discoveries.
1 Juan Fernandez is a good example of a small island which, with time
and favourable conditions, has acquired a tolerably rich and higlily peculiar
liora and fauna. It is situated in 34° S. Lat., 400 miles from tlie coast
of Chile, and so far as facilities for the transport of livi}ig organisms arc
concerned is by no means in a favourable position, for the ocean-currents
come from the south-west 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 its antiquity, its varied surface, and its
favourable soil and climate, oftering many chances for the preservation and
increase of whatever plants and animals have chanced to reach it. The
island consists of basalt, greenstone, and other ancient rocks, and thougli
only about twelve miles long its mountains are three thousand feet higli.
Enjoying a moist and temperate climate it is especially adajited 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 surprising that there are nearly fifty species on the island, while the
remote period when it first received its vegetation may lie indicated by the
fact that nearly half the species are quite peculiar ; while of 102 species of
fiowering plants seventy are peculiar, and there are ten peculiar genera.
The same general character pervades the fauna. For so small an ishnnl
it is rich, containing four true land-birds, about fifty species of insects,
and twenty of land-shells. Almost all these belong'to South American
genera, and a large proportion are South American species ; but several of
the insects, half the birds, and the whole of the land-shells are peculiar.
This seems to indicate that the means of transmission were formerly greater
than they are now, and that in the case of land-shells none have been in-
troduced for so long a period that all liavc become modified into distinct
forujs, or have been preserved on the island while they liave liecome extinct
on the continent. For a detailed examination of the causes wliich liave
led to the modification of the humming ))irds of Juan Fernandez see tin"
'hapter on Hununing liirds in the author's A7</»?-a/ Schrtion and Tiopicnl
Xature, p. ,324 ; while a general account of the fauna of tlu- island is given
in his Geographical Distribution uf Animals, Vol. II. p. 4y.
288 ISLAND LIFE
The total number of flowering plants known at tlie latter
date was 332, of Avliicli 174 were peculiar to the islands,
while 158 were common to other countries.^ Of these
latter about twenty have been introduced by man, while
the remainder are all natives of some part of America,
though about a third part are species of wdde range ex-
tending into both hemisiDheres. Of those confined to
America, forty-two are found in both the northern and
southern continents, twenty-one are confined to South
America, while twenty are found only in North America,
the West Indies, or Mexico. This equality of North
American and South American species in the Galapagos
is a fact of great significance in connection wath the
observation of Sir Joseph Hooker that the ^jeculiar species
are allied to the plants of temperate America or to those
of the high Andes, while the non-peculiar species are
mostly such as inhabit the hotter regions of the tropics
near the level of the sea. He also observes that the seeds
of this latter class of Galapagos plants often have special
means of transport, or belong to groups w^hose seeds are
known to stand long voyages and to possess great vitality.
Mr. Bentham also, in his elaborate account of the Com-
posita?,- remarks on the decided Central American or
Mexican affinities of the Galapagos sj^ecies, so that w^e may
consider this to be a thoroughly w^ell-established fact.
The most prevalent families of plants in the Galapagos
are the Compositae (40 sp.), Gramineae (32 sp.), Legumi-
nosae (30 sp.), and Euphorbiacese (29 sp.). Of the Com-
positae most of the species, except such as are common
weeds or shore plants, are peculiar, but there are only
two peculiar genera, allied to Mexican forms and not
very distinct; wdiile the genus Lipochaeta, represented
here by a single species, is only found elsewhere in the
Sandwich Islands though it has American affinities
Origin of the Galcrpagos Flora. — These facts are ex-
plained by the past history of the American continent, its
^ Xo additions appear to have been made to this flora down to 1885,
when Mr. Hemsley published his Rciwrt on the Present State of our Ktiow-
ledge of Imular Floras.
- JuurnaJ of the Linnean Society, Vol. XIII., "Botany," p. 556.
CHAP. XIII THE GALAPAGOS ISLANDS
separation at various epochs by arms of the sea uniting tlie
two oceans across what is now Central America (the last
separation being of recent date, as shown by the consider-
able number of identical species of fishes on both sides of
the isthmus), and the influence of the glacial epoch in
driving the temperate American flora southward 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 of 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 dura-
tion of the last glacial epoch in its successive phases was
much longer than the time which has elapsed since it
Anally passed away, while throughout the Miocene epoch
the snow-line Avould often be lowered during periods of
high excentricity, we are enabled to comprehend the
nature of the causes which may have led to the islands
being stocked with those north tropical or mountain types
which are so characteristic a feature of that portion of the
Galapagos flora which consists of peculiar sj^ecies.
On the whole, the flora agrees with the fauna in in-
dicating a moderately remote origin, great isolation, and
chaiiofes of conditions affordino- facilities for the introduc-
tion of organisms from various parts of the American
coast, and even from the West Indian Islands and Gulf of
Mexico. As in the case of the birds, the 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 lead to the
differentiation of species, while the varied conditions to be
found upon islands differing in size and altitude as well as
in luxuriance of vegetation, would often lead to the ex-
tinction of a species on one island and its preservation on
another. If the several islands had been equally well
^ Geographical Distribution of Aniiaals, Vol. 11. \k ^^■
I"
290 ISLAXD LIFE Tart ]1
explored, it might be interesting to see whether, 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 the
group is exceedingly unequal, and, except in those cases
in which representative species inhabit distinct islands, we
have no certainty on the subject. All the more interesting
problems in geographical 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 most part confine ourselves to this aspect of the
question in our discussion of the phenomena presented by
oceanic or continental islands.
Concluding Eemarks. — The GalajDagos offer an instructive
contrast with the Azores, showing how a difference of con-
ditions that might be thouglit unimportant may yet pro-
duce very striking results in the forms of life. Although
the Galapagos are much nearer a continent than the
Azores, the number of species of plants common to the
continent is much less in the former case than in the latter,
and this is still more prominent a characteristic of the
insect and the bird faunas. 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 im-
portance of the atmosphere as an agent in the dispersal of
birds, insects, and plants. Yet ocean-currents and surface-
drifts are undoubtedly eflicient 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 of several West Indian
types at a more remote period when the Isthmus of Panama
was submerged.
In the case of these islands we see the importance of
taking account of past conditions of sea and land and past
changes of climate, in order to explain the relations of the
peculiar or endemic 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 teni-
CHAP, xni THE GALAPAGOS ISLANDS iiOl
perate or alpine affinities of many of the plants, and even
of some of the birds. The relation between the migratory
habits of the birds and the amount of difference from
continental types is strikingly accordant with the fiict that
it is almost exclusively migratory birds that annually 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, have all — as Sir
Joseph Hooker states — some special means of dispersal, is
equally intelligible. The reason Avhy the Galapagos ])os-
sess 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 tlie influence of such
modified winds and currents as might convey them to the
islands.
On the whole, then, we have no dithculty in explaining
the probable origin of the flora and fauna of the Galapagos,
by means of the illustrative facts and general principles
already adduced.
CHAPTER XIV
ST. HELENA
Position and Physical Featm-es of St. Helena — Change Effected by
European Occupation — The Insects of St. Helena — Coleoptera — Pecu-
liarities and Origin of the Coleoptera of St. Helena — Land-shells of St.
Helena — Absence of Fresh-water Organisms — Kative Vegetation of St.
Helena — The Relations of the St. Helena Compositte — Concluding
Remarks on St. Helena.
In order to illustrate as completely as possible the peculiar
phenomena of oceanic islands, we will next examine the
organic productions of St. Helena and of the Sandwicli
Islands, since these combine in a higher degree than any
other spots upon the globe, extreme isolation from all
more extensive lands, with a tolerably rich fauna and flora
whose jDeculiarities are of surpassing interest. Both, too,
have received considerable attention from naturalists ; and
though much still remains to be done in the latter group,
our knowledge is sufficient to enable us to arrive at many
interesting results.
Position and Physical Features of St. Helena. — This
island is situated nearly in the middle of the South
Atlantic Ocean, being more than 1,100 miles from the
coast of Africa, and 1,800 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 for
294 ISLAND LIFE part ii
tlie most part by enormous precipices, and rising to a
height of 2,700 feet above the sea-level. An ancient
crater, about four miles across, is open on the south side,
and its northern rim forms the highest and central ridge of
the island. Many other hills and peaks, however, are more
than two thousand feet high, and a considerable portion of
the surface consists of a rugged jilateau, having an
elevation of about fifteen hundred to two thousand feet.
Everything indicates that St. Helena is an isolated volcanic
mass built up from the depths of the ocean. Mr.
Wollaston remarks : " There are the strongest reasons for
believing that the area of St. Helena was never irru much
larger than it is at present — the comparatively shallow
sea-soundings w^ithin about a mile and a half from the
shore revealing an abruptly defined ledge, beyond which no
bottom is reached at a depth of 250 fathoms ; so that the
original basaltic mass, which was gradually piled up by
means of successive eruptions from beneath the ocean,
would appear to have its limit definitely marked out by
this suddenly-terminating submarine cliff — the space
between it and the existing coast-line being reasonably
referred to that slow process of disintegration by which the
island has been reduced, through 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
south-easterly direction, is a profound oceanic gulf known
to reach a depth of 2,860 fathoms, or 17,160 feet, while an
equally deep, or perhaps deeper, ocean, extends to the west
and south-west, we shall be satisfied that St. Helena is a
true oceanic island, and that it owes none of its
peculiarities to a former union with any continent or other
distant land.
Change Effected hy European Occupation. — When first
discovered, in the year 1.501, St. Helena was densely
covered with a luxuriant forest vegetation, the trees over-
hanging the seaward precipices and covering every part of
the surface Avith an evergreen mantle. This indigenous
vegetation has been almost wholly destroyed ; and although
an immense number of foreign plants have been introduced,
and have more or less completely established themselves,
CHAP. XIV ST. HELENA 295
yet the general aspect of the island is now so 1)arren and
forbidding that some persons find it difficult to believe that
it was once all green and fertile. The cause of the change
is, however, very easily explained. Tho rich soil formed
by decomposed volcanic rock and vegetable deposits could
only be retained on the steep slopes so long as it was
protected by the vegetation to which it in great part owed
its origin. When this was destroyed, the heavy trojiical
rains soon washed away the soil, and has left a vast
expanse of bare rock or sterile clay. This irreparable
destruction was caused in the first place by goats, which
were introduced by the Portuguese in 15 13, and increased
so rapidly that in 1588, they existed in thousands. These
animals are the greatest of all foes to trees, because they
eat off the young seedlings, and thus prevent the natural
restoration 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 protection. 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 large
quantity of the rapidly disappearing ebony was used to
burn lime for building fortifications ! By the MSS. records
quoted in Mr. Melliss' interesting volume on St. Helena,Mt
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 flourishing condition, full of 3^oung trees, where the
hoggs (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 we 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 was not inhabited when the people first
1 St. Helena: a Physical, Historical, and Topographical Drseription of
the Island, cOc. By John Charles Melliss, F.G.S., &c. London : 1875.
296 ISLAND LIFE
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 w^ould
produce 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 wall soon be ruined " . . . .
" We viewed the wood's end which joins the Honourable
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 soil between being
washed away, that distance is now entirely barren." (MSS.
records, 1716.) In 1709 the governor reported to the
Court of Directors of the East India Company that the
timber was rapidly disappearing, and that the goats should
be destroyed for the preservation of the ebony wood, and
because the island was suffering from droughts. The reply
was, " The goats are not to be destroyed, being more
valuable than ebony." Thus, through the gross ignorance
of those in power, the last opportunity of preserving the
peculiar vegetation of St. Helena, and preventing the
island from becoming the comparatively rocky desert it
now is, was allowed to pass away.^ Even in a mere
1 Mr. Marsh in his interesting work entitled The Earth as Modified bij
Human Action (p. 51), thus remarks on the effect of browsing quadrupeds
in destroying and checking woody vegetation. — "I am convinced that
forests woukl soon cover many parts of the Arabian and African deserts
if man and domestic animals, especially the goat and the camel, were
banished from them. The hard palate and tongue, and strong teeth and
jaws of this latter quadruped enable him to break oif and masticate tough
and thorny branches as large as the finger. He is particularly fond of the
smaller twigs, leaves, and seed-pods of the Sont and other acacias, which,
like the American robinia, thrive well on dry and sandy soils, and he
spares no tree the branches of which are within his reach, excej)t, if I
remember right, the tamarisk that produces manna. Young trees sprout
plentifully around the springs and along the winter water-courses of the
desert, and these are just the halting stations of the caravans and their
routes of travel. In the shade of these trees annual grasses and perennial
shrub? shoot up, but are mown down by the hungry cattle of the Bedouin
riiAr. XIV
ST. HELENA 297
pecuniary point of view the error was a fotal one, for intlie
next century (in 1810) another governor reports the total
destruction of the great forests hy the goats, and that in
consequence the cost of importing fuel for government use-
was 2,720/. 75. 8^/. for a single year ! About this time
large numbers of European, American, Australian, and
South African plants were imported, and many of these ran
wild and increased so rapidly as to drive out and
exterminate much of the relics of the native flora ; so that
now English broom gorse and brambles, willows and
poplars, and some common American, Cape, and Australian
weeds, alone meet the eye of the 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 ahnost total extirpation of a luxuriant and highly
peculiar 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. ^lany
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
Canaries, undertook a voyage to St. Helena for the exi)ress
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 labours
are contained in two volumes,^ which, like all that he
wi'ote, are models of accuracy and research, and it is to
these volumes that we are indebted for the interesting
and suggestive facts which we here lay before our readers.
as fast as they grow. A few years of undisturbed vegetation would sufFico
to cover such points with groves, and these wouhl gradually extend them-
selves over soils where now scarcely any green ^ thing but the bitter
colocynth and the poisonous foxglove is ever seen."
1 Coleoptcra Sanctcc Hclenm, 1877 ; Tcslacca Atlnntica, 1S78.
298 ISLAND LIFE
Insects — CoIco2?tera. — The total number of species of
beetles hitherto observed at St. Helena is 203, but of these
no less than seventy-four are common and Avide-spread
insects, which have certainly, in Mr. Wollaston's opinion,
been introduced by human agency. There remain 129
which are believed to be truly aborigines, and of these all
but one are found nowhere else on the globe. But in
addition to this large amount of specific ^peculiarity (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 are peculiar to the island ; and many of these are
such isolated forms that it is impossible to find their allies
in any particular country. Still more remarkable is the
fact, that more than two-thirds of the whole number of
indigenous species are Rhyncophora or weevils, while more
than two-fifths (fifty-four species) belong to one family, the
Cossonidse. Now although the Rhyncophora are an
immensely numerous group and always form a large por-
tion of the insect population, they nowhere else approach
such a proportion as this. For example, in Madeira they
form one-sixth of the whole of the indigenous Coleoptera,
in the Azores less than one-tenth, and in Britain one-
seventh. Even more interesting is the fact that the twenty
genera to v/hich these insects belong are every one of
them peculiar to the island, and in many cases have no
near allies elsewhere, so that we cannot but look on this
group of beetles as forming the most characteristic portion
of the ancient insect fauna. Now, as the great majority
of these are wood borers, and all are closely attached to
vegetation and often to particular species of plants, we
might, as Mr. Wollaston well observes, deduce the former
luxuriant vegetation of the island from the great pre-
ponderance of this group, even had we not positive evidence
that it was at no distant epoch densely forest-clad. We
will now proceed briefly to indicate the numbers and
peculiarities of each of the families of beetles which
enter into the St. Helena fauna, taking them, not in
CHAr. XTV ST. HELENA 299
systematic order, but according to their iinjiortanre in tin-
island.
1. Rhyxcophora. — This great division incliid.s thr
weevils and allied groups, and, as above stated, exceeds in
number of species all the other beetles of tlie island. Four
families are represented ; the Cossonida^, with fifteen
peculiar genera comprising fifty-four species, and one
minute insect (Stcnoficriis hylastoides) forming a peculiar
genus, but which has been found also at the Cnpe of Good
Hope. It is therefore impossible to say of which country
it is really a native, or whether it is indigenous to both,
and dates back to the remote period when St. Helena
received its early emigrants. All the Cossonida? are found
in the highest and wildest parts of the island where tlif
native vegetation still lingers, and many of them are only
found in the decaying stems of tree-ferns, box-wood,
arborescent Compositoe, and other indigenous plants.
They are all pre-eminently peculiar and isolated, having
no direct affinity to species found in any other country.
The next family, the Tanyrhynchid?e, has one peculiar
genus in St. Helena, with ten species. This genus (Nesiotes ^
is remotely allied to European, Australian, and ^ladeiran
insects of the same family : the habits of the s]H'cies arc
similar to those of the Cossonida^. The Trachyphlo?ida^ arc
represented by a single species belonging to a peculiar
genus not very remote from a European form. The An-
thribidii? again are highly peculiar. There are twenty-six
species belonging to three genera, all endemic, and so
extremely peculiar that they form two new subfamilies.
One of the genera, Acarodes, is said to be allied to a
Madeiran genus.
2. Geodephaga. — These are the terrestrial carnivor-^us
beetles, very abundant in all parts of the world, especially
in the temperate regions of the northern hemisphere. In
St. Helena there are fourteen species belonging to three
genera, one of which is peculiar. This is the Ifaph'thirnx
burchellii, the largest beetle on the island, and now very
rare. It resembles a large black Garabus. There is also
a peculiar Calosoma, very distinct, though resembling in
some respects certain African sju^cies. Tlif rest c^f the
300 ISLAND LIFE
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. Heteromera. — This group is represented by three
peculiar genera containing four species, with two species
belonging to European genera. They belong to the families
Opatridse, Mordellidoe, and Anthicidse.
4. Brachyelytra. — Of this grouj) there are six peculiar
species belonging to four European genera — Homalota,
Philonthus, Xantholinus, and Oxytelus.
5. Priocerata. — The families Elaterida; and Anobiidse
are each represented by a peculiar species of a European
genus.
6. PhytophaGA. — There are only three species of tliis
tribe, belonging to the European genus Longitarsus.
7. Lamellicornis. — Here are three species belonging
to two genera. One is a peculiar species of Trox, allied to
South African forms ; the other two belong to the peculiar
genus Melissius, which Mr. Wollaston considers to be
remotely allied to Australian insects.
8. PsEUDO-TRlMERA. — Here we have the fine lady-bird
Chilomcnns lunata, also found in Africa, but apparently
indigenous in St. Helena; and a peculiar species of
Euxestes, a genus only found elsewhere in Madeira.
9. Trichopterygid.e. — These, the minutest of beetles,
are represented by one species of the European and
Madeiran genus Ptinella.
10. Necrophaga. — One indigenous species of Crypto-
phaga inhabits St. Helena, and this is said to be very
closely allied to a Cape species. .
Fcculiaontics and Origin of the CoIcc]itcra of Bt. 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 inhabiting Europe, Madeira, or South
Africa. These facts clearly point to the very great anti-
quity of the insect fauna of St. Helena, which has allowed
ntAr. XTV
ST. HELENA 301
time for the modification of the originally intruihicod
species, and their special adaptation to the conditions ])n'-
vailing in this remote island. This antiquity is also shuwn
by the remarkable specific modification of a few typi-s.
Thus the whole of the Cossonidaj may be referred tu tliri'c
types, one species only {Hcxacoptus ferruginms) being allied
to the European Cossonidte though forming a distinct
o-enus ; a group of three genera and seven species renicjtely
allied to the Stcnoscelk hylastoidcx, which occurs also at tlu*
Cape ; while a group of twelve genera with forty-six sjiccies
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 Bem-
bidium form a group by themselves ; and the Heteromera
form two groups, one consisting of three genera and species
of Opatridie aUied to a type found in Madeira, the other,
Anthicodes, altogether peculiar.
Now each of these types may well be descended from a
single species which originally reached the island from some
otlier land ; and the great variety of generic and specific
forms into which some of them have diverged is an indica-
tion, and to some extentameasure, of the remoteness of their
origin. The rich insect fauna of Miocene age found in
Swl^tzerland consists mostly of genera which still inhabit
Europe, with others which now inhabit 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 improbably
to a still earlier, epoch. But if so, many difticulties 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, inliabited
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 tem-
perate zones towards the equator, and the reverse. It,
therefore, the nearest ally of any insular group now m-
habits a particular country, we are not obliged to suppose
that it reached the island from that country, smce we
know that most groups have ranged in i)ast times over
302 ISLAND LIFE
wider areas than they now inhabit. Neither are we
limited to the means of transmission 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
inevitable, 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 con-
stantly at St. Helena, and the ocean-currents flow in the
same direction, so that any transmission of insects by
their means must almost certainly be from South Africa.
Now there is undoubtedly a South African element 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 con-
sider that this northern element is chiefly represented by
remote generic affinity, and has therefore all the signs of
great antiquity, we find a possible means of accounting
for it. We have seen that during early Tertiary times an
almost tropical climate extended far into the northern
hemisphere, and a temperate climate to the Arctic regions.
But if at this time (as is not improbable) the Antarctic
regions were as much ice-clad as they are now it is certain
that an enormous change must have been produced in the
winds. Instead of a great difference of temperature be-
tween each pole and the equator, the difference would be
mainly between one hemisphere and the other, and this
might so disturb the trade winds as 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 this remote epoch the
mountains of equatorial Africa may have been more
extensive than they are now, and may have served as
intermediate stations by which some northern insects may
have migrated to the southern hemisphere.
We must remember also that these peculiar forms are
said to be northern only because their nearest allies are
CHAP. XIV ST. HELENA. 303
now found in the Nortli Atlantic isUuids and Southern
Europe ; but it is not at all impruhable tliat they are reallv
widespread Miocene types, which liave been ])reserve(l
mainly in favourable insular stations. They may tlierc-
fore have originally reached St. Helena from Southern
Africa, or from some of the Atlantic islands, and may liave
been conveyed by oceanic currents as well as by winds.^
This is the more probable, as a large proportion of tlie St.
Helena beetles live even in the perfect state within tin;
stems of plants or trunks of trees, while the eggs and
larvie of a still larger number are likely to inhabit similar
stations. Drift-w^ood 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 gr(iii|)s
support the conclusions derived from a consideration of tin-
beetles. The Hemij^tera 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 distributed, .while one
of the peculiar genera is of African type. The other
orders of insects have not been collected or studied with
^ On Petermann's map of Africa, iu JSticlcr's Hand-Atkts (1879), tin;
Island of Ascension is shown as seated on a much larger and shallower
submarine bank than St. Helena. The 1,000 fathom line round Ascension
encloses an oval space 170 miles long by 70 wide, and even the 300
fathom line, one over 60 miles long ; and it is therefore ])robable that
a much larger island once occujned this site. Xow Ascension is nearly
equidistant between St. Helena and Liberia, and sueh an island mi,i,'lit
have served as an intermediate station through which many of the im-
migrants to St. Helena passed. As the distances are hardly greater than
in the case of the Azores, this removes whatevt'r ililiiculry may have btcii
felt of the possibility of any organisms reaching so remote an island.
The i)resent island of Ascension is ja-obably only the summit i»f a liugi'
volcanic mass, and any remnant of the original fauna and llora it might
have preserved may have been destroyed by great volcanic eruiitions. Mr.
Darwin collected some masses of tufa which were found to b«' mainly
organic, containing, besides remains of fresh-water infusoria, the silieeuus
tissue of plants ! In the light of the great extent of the submarine bank
on which the island stands, ]\Ir. Darwin's remaik, that — "we may feel
sure, that at some former epoch, the climate and productions of Ascension
were very different from wliat they are now," — has received a .striking
conlirnuition. {Hl'Q ^^alicralial'^ ]'u>ja<jc Iluand the Jl'oild, p. -k^JJ.)
304 ISLAND LIFE
sufficient care to make it worth while to refer to them in
detail ; but the land-shells have been carefully collected
and minutely 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 conditions of life ; so that
there remain exactly twenty species which may be con-
sidered truly indigenous. No less than thirteen of these,
however, appear to be extinct, being now only found on
the surface of the gi'ound or in the surface soil in places
where the native forests have been destroyed and the land
not cultivated. These twenty j^eculiar 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
Bulimi, and two of Subulina are extinct. The three
Hyalinas are allied to European species, but all the rest
appear to be highly peculiar, and to have no near allies
with the species of any other country. Two of the Bulimi
{B. auris vuljnno) and B. darivinianus) are said to some-
what resemble Brazilian, New Zealand, and Solomon
Island forms, while neither Bulimus nor Succinea occur
at all in the Madeira group.
Omitting the species that have probably been introduced
by human agency, we have here indications of a somewhat
recent immigration of European types which may perhaps
be 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 Frcsli-ivater Organisms. — A singular pheno-
menon 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-jjlauts in the streams, except the common
CHAT'. XIV ST. HELENA 305
water-cress, one or two species of Cypenis, aii<l tin-
Australian Isapis ]jrolifera. The same absence of fresh-
water shells characterises the Azores, where, however, tliere
is one indigenous Avater-beetle. In the Sandwich Islands
also recent observations refer to tlie absence of water-
beetles, though here there are a few fresh-water shells. It
would ajDpear therefore that the wide distribution of the
same generic and specific forms which so generally
characterises 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 which we are at
present ignorant.
The other classes of animals in St. Helena need occupy
us little. There are no indigenous mammals, reptiles,
fresh- water fishes or true land -birds ; but there is one
species of wader — a small plover {/Erjialitis sanctcr-helence)
— very closely allied to a species found in South Africa, but
presenting certain differences which entitle it to the rank
of a peculiar 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 better to understand the biological relations
and probable history of the island.
ISative 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. Their seeds are
often so minute, of sucli small specific gravity, or so
furnished with downy or winged appendages, as to be
carried by the wind for enormous distances. The bristles
or hooked spines of many small fruits cause tliem 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 ]\Ir.
Melliss, that large seeds which have floated from
X
306 ISLATTD LIFE part ii
Madagascar or Mauritius round the Cape of Good Hope,
have been thrown on the shores of St. Helena and have
then sometimes germinated !
We have therefore little difficulty in understanding lioic
the island was first stocked with vegetable forms. When
it was so stocked (generally speaking), is equally clear.
For as the peculiar coleoi^terous fauna, of which an im-
portant fragment remains, is mainly comjDosed of species
which are sioecially attached to certain groups of plants, we
may be sure that the plants were there long before the
insects could establish themselves. However ancient then
is the insect fauna the flora must be more ancient still.
It must also be remembered that plants, when once
established in a suitable climate and soil, soon take
possession of a country and occuj^y it almost to the
complete exclusion of later immigrants. The fact of so
many European weeds having overrun New Zealand and
temperate North America may seem opposed to this state-
ment, but it really is not so. For in both these cases the
native vegetation has first been artifically 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 flora of such an
island as St. Helena w^ould be of an excessively ancient
type, preserving for us in a slightly modified form
examples of the vegetation of the globe at the time wdien
the island first rose above the ocean. Let us see then
what botanists tell us of its character and affinities.
The truly indigenous flowering 23lants are about fifty in
number, besides twenty-six ferns. Forty of the former and
ten of the latter are absolutely peculiar to the island, and,
as Sir JosejDh Hooker tells us, " with scarcely an exception,
cannot be regarded as very close specific allies of any other
plants at all. Seventeen of them belong to peculiar
genera, 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 continental species."
The affinities of this flora are, Sir Joseph Hooker thinks,
ST. HELRXA r^o;
mainly African and especially South African, as indicated
by the presence of the genera Phylica, Pclar^c'iiiuin,
Mesembryanthemum, Oteospermum, and Walik-nber^ia,
which are eminently characteristic of southern extra-tropical
Africa. The sixteen ferns -whicli 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 unknown distances by the wind,
and the great stability of their generic and specific forms,
many of those found in the Miocene deposits of Switzer-
land, being hardly distinguishable from living species.
This shows, that identity of siiccics of ferns between St.
Helena and distant countries does not necessarily imply a
recent origm.
TIlc Fidation of the St. Helena ComposUcn. — In an
elaborate paper on the Compositse,^ Mr. Bentham gives us
some valuable remarks on the affinities of the seven
endemic species belonging to the genera Commidendron,
Melanodendron, Petrobium, and Pisiadia, which forms so
important a portion of the existing flora of St. Helena.
He says : " Although nearer to Africa than to any other
continent, those composite denizens which bear evidence 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
Melanodendron are among the woody Asteroid forms
exemplified in the Andine Diplostephium, and in tlie
Australian Olearia. Petrobium is one of three genera,
remains of a group probably of great anti(]uity, of which
the two others are Podanthus in Chile and Astemma in
the Andes. The Pisiadia is an endemic species of a genus
otherwise Mascarcne or of Eastern Africa, presenting a
geographical connection analogous to that of the St. Tlek'na
Melliania%- with the Mascarene Trochetia.''
Whenever such remote and singular cases of geo-
graphical affinity as the above are i)ointed out, the first
1 "Notes on the Classification, History, and Geographical Di.strilmtion
of Compositie." — Journal of t/ic Linnran Sucirti/, Vol. XIII. p. r)G:j (1S73).
- The Melhanire comjiri-e the two finest timber trees of St. Helena, now
almost extinct, the redwood and native ebony.
X '2
308 ISLAND LIFE
impression is to imagine some mode by which a com-
munication between the distant countries impUcated
might be effected ; and this way of viewing the problem is
almost universally adopted, even by naturalists. But if
the principles laid down in this work and in my Geo-
gra'pliical 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 frag-
mentary groups and isolated forms are but the relics of
once widespread types, which have been preserved in a few
localities where the physical conditions were especially
favourable, or where organic competition was less severe.
The true explanation of all such remote geographical
affinities is, that they date back to a time when the
ancestral group of which they are the common descendants
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 Equidge 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 com-
munication.
Concluding BcmarlxS on St. Helena. — The sketch we
have now given of the chief members 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 ocean, all the
more important facts become readily intelligible. 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 became stocked by chance immigrants from other
countries at some remote epoch, and which has jDreserved
many of their more or less modified descendants to the
present time. When first visited by civilised man it was
in all probability far more richly stocked with plants and
animals, forming a kind of natural museum or vivarium in
which ancient types, perhaps dating back to the Miocene
cHAr. XIV ST. HELENA 309
period, or even earlier, had been saved Ironi tli(3 duslruc-
tioD which has overtaken their allies on tlie great con-
tinents. Unfortunately many, we do not know how-
many, of these forms have been exterminated by tin-
carelessness and improvidence of its civilised 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.
CHAPTER XV
THE SANDWICH ISLANDS
Position and Physical Features— Zoology of the Sandwich Islands— Birds
—Reiitiles— 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— General Remarks on Oceanic Islands.
The Sandwich Islands are an extensive group of large
islands situated in the centre of the North Pacific, being
2,350 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 arc
only connected with the other Pacific Islands by widely
scattered coral reefs and atolls, the nearest of which,
however, are six or seven hundred miles distant, and are
all nearly destitute 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 3,800 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 high.
CHAP. XV
THE SANDWICH ISLANDS
Three of the smaller islands are each about the size of
Hertfordshire or Bedfordshire, and the whole group
stretches from north-west to south-east for a distance of
about 350 miles. Though so extensive, the entire archi-
pelago is volcanic, and tlie largest island is rendered
|isow
|I56_
MAP OF rni: sandwich i.sI-anps.
The light tint shows where the sea is less tlian 1,000 fallioins (lc'_'i>.
The figrres show the dcjith in fathoms.
sterile and comparatively uninhabitable by its tUrw active
volcanoes and their wides})rcad deposits ot lava.
The ocean depths by which these islands are separated
from the nearest continents are enormous. North, ciist,
and south, soundings have been ol)tained a little over or
under three thousand fathoms, and tliese profound^ deeps
extend over a large part of the Nnrtli Pacific. We may
312
ISLAND LIFE
be quite sure, therefore, that the Sandwich Islands liave,
during their whole existence, been as completely severed
from the great continents as they are now; but on the
140 130
MA1> OF THE KORTH PACIFIC WITH ITS SUBllERGED BANKS.
The light tint sliows where the sea is less than 1,000 fathoms deep.
The dark tint ,, „ ,, more than 1,000 fathoms deep.
The figures show the' depths in fathoms.
west and south there is a possibility of more extensive
islands having existed, serving as stepping-stones to the
island groups of the Mid-Pacific. This is indicated by a
few widely-scattered coral islets, around which extend
THE SANDWICH ISLANDS 313
cousiderable areas of less depth, varying- fmiu two hiintlrud
to a thousand fathoms, and which may therefore indicate
the sites of submerged islands of considerable extent.
When we consider that east of New Zealand and New
Caledonia, all the larger and loftier islands are of volcanic
origin, with no trace of any ancient stratified rocks
(except, perhaps, in the Marquesas, where, according to
Jules Marcou, granite and gneiss are said to occur) it
seems probable that the innumerable coral-reefs and atolls,
which occur in groups on deeply submerged Ixmks, mark
the sites of bygone volcanic islands, similar to those
which now exist, but which, after becoming extinct, have
been lowered or destroyed by denudation, and finally have
altogether disappeared except where their sites are
indicated by the upward-growing coral-reefs. If this vii-w
is correct we should give up all idea of there ever having
been a Pacific continent, but should look upon that vast
ocean as having from the remotest geological epochs been
the seat of volcanic forces, which from its profound dejitlis
have gradually built up the islands which now dot its
surface, as well as many others Avhich have sunk beneath
its waves. The number of islands, as well as the total
cpiantity of land-surface, may sometimes lia\e been
greater than it is now, and may thus have facilitated tlie
transfer of organisms from one group to another, and more
rarely even from the American, Asiatic, or Australian
continents. Keeping these various facts and considera-
tions in view, we may now jn-oceed to examine the la-una
and fiora of the Sandwich Islands, and discuss the special
phenomena they present.
Zoology of tlic Sandwich Islands: Birds.— -It need lianlly
be said that indigenous mannnalia are quite unknown in
the Sandwich Islands, the most interesting of the highei-
animals being the birds, which are tolerably numerous an<l
highly peculiar. Many aquatic and wiidhig birds whicli
range over the wdiole Pacific visit these islands, twenty-
five species having been observed, but even of tliese six
are peculiar — a coot, Fulica alai ; a moorhen, Uallumla
f/aleata var sandvichensis ; a rail with rudimentary wnigs
Pcnnula millci ; a stilt-plover, Himaniojuis hiiuhcni ; anc.
314 ISLAND LIFE part ii
two ducks, Anas Wyvilliana and Bernida sandvichensis.
The birds of prey are also great wanderers. Four have
been found in the islands — the short-eared owl, Otus
hrachyotus, which ranges over the greater part of the globe,
but is here said to resemble the variety found in Chile
and the Galapagos; the barn owl, Strix flammea, of a
variety common in the Pacific ; a peculiar sparrow-hawk,
Acci]jitcTlw.u-aii ; and Buteo solitarius, a buzzard of a peculiar
species, and coloured so as to resemble a hawk of the
American subfamily Polyborina?. It is to be noted that
the genus Buteo abounds in America, but is not found in
the Pacific ; and this fact, combined with the remarkable
colouration, renders it almost certain that this peculiar
species is of American origin.
The Passeres, or true perching birds, are especially
interesting, being all of peculiar species, and, all but one,
belonging to peculiar genera. Their numbers have been
greatly increased since the first edition of this work
appeared, partly by the exertions of American naturalists,
and very largely by the researches of Mr. Scott B. Wilson,
who visited the Sandwich Islands for the jourpose of
investigating their ornithology, and collected assiduously
in the various islands of the group for a year and a half.
This gentleman is now publishing a finely illustrated
\vork on Hawaiian birds, and he has kindly furnished me
with the following list.
Passeres of the Sandwich Islands.
MuscicAriD>E (Flycatcliers).
1. Chaskiivpisridgwayi Hawaii.
2. ,, sdatcri Kauai.
3. , , dolci Kauai,
4. ,, fjayi Oahu.
5. ,, ibidis Oahu.
6. Fhccornis obscura Hawaii.
7. ,, myadestina Kauai.
Meliphagid^ (Honeysucker.s).
8. Acruloccrcus nobilis Hawaii.
9. ,, braccatus Kauai.
10. ',, apicalis (extinct) Oahu or ]\l:iui.
11. Ohcetoptila anrjustipluma (extinct) Hawaii.
THE SANDWICH ISLANDS 316
Drepanidid^.
12. Drcpanis pacifica (extinct) Hawaii.
13. Fasiiana coccinm All tlic I.shiiids.
14. Hiniationc vireus Hawaii.
15. ., dolii IMaiii.
16. ,, sanguinca All the LslaiuLs.
17. ,, montana Lanai.
18. ,, chloria Oahii.
19. ,, onaculala Oahu.
20. ,, parva Kauai.
21. ;, stejnegeri Kauai.
22. Oreomyza hairdi Kuuai.
23. Hcmignatlms ohscurus Hawaii.
24. ,, olixaccus Hawaii.
25. ,, lichtcnsteini Oaliu.
26. . , Jucidus Oahu.
27. ,, stejnegeri Kauai.
28. ,, hanapepe Kauai.
29. Loxops coccinca Hawaii.
30. ,, fiammea Molokai.
31. , , aiirea !Maui.
32. Chrysoniitridops coerulcorostris Kaui.
33. ,, an?i« (extinct)
Frixgillid.i^ (Finches).
34. Loxioides hailleni Hawaii.
35. Psittirodra psUtacca All the Lslands.
36. Chloridops kona Hawaii.
ConviDiE (Crow.s;.
37. Corvus Jiaicaiiensis Hawaii.
Many uf the birds recently described are re})ri'sentativc
forms found in the several islands of the grouj).
Taking the above in the order here given, ue iia\e.
first, two peculiar genera of true flycatchers, a family con-
fined to the Old World, but extending over the Pacific as
far as the Marquesas Islands. Next wo 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 lome
to the most important group of birds in the Sandwieli
Islands, comprising seven or eight peculiar genera, and
twenty-two species which are believed to form a ]U'culiar
family allied to the Oriental flower-]ieckers (DiceidaO, and
perhaps remotely to the American greenlets (Vireouida*;, "i"
316 ISLAND LIFE
tanagers (Tanagridse). 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
almost universally distributed genus Corvus.
On the whole, the affinities of these birds are, as might
be expected, chiefly with Australia and the Pacific Islands ;
but they exhibit in the buzzard, one of the owls, and
perhaps in some of the Drepanididae, slight indications of
very rare or very remote communication with America.
The amount of speciality is, however, wonderful, far
exceeding that of any other islands ; the only approach to
it being made by New Zealand and Madagascar, which
have a much more varied bird fauna and a smaller |j>rc-
Ijortionatc number of peculiar genera. The Galaj)agos,
among the true oceanic islands, while presenting many
peculiarities have only four out of the ten genera of Passeres
peculiar. These facts undoubtedly indicate an immense
antiquity for this group of islands, or the vicinity of some
very ancient land (now submerged), from Avhich some
portion of their peculiar fauna might be derived. For
further details as to the affinities and geographical dis-
tribution of the genera and species, the reader must consult
Mr. Scott Wilson's work The Birds of tlic Sandwich Islands,
already alluded to.
Beptilcs. — The only other vertebrate animals are two
lizards. One of these is a very Avidespread species,
AUepharus 2^oecilophLiTus, ranging from the Pacific Islands
to West Africa. The other is said to form a peculiar
genus of geckoes, but both its locality and affinities appear
to be somewhat doubtful.
Land-shells. — The only other group of animals which
has been carefully studied, and Avhicli joresents features of
especial interest, are the land-shells. These are very
numerous, about thirty genera, and between three and four
hundred species having been described ; and it is remark-
able that this single group contains as many sj^ecies of
THE SANDWICH ISLANDS 31
land-shells as all the other Polynesian Islands fVum tlic
Pelew Islands and Samoa to the Marquesas. All t\nt
species are peculiar, and about three-fourths of the whole
belong to peculiar genera, foiuieen of Avhich constitute the
sublamily Achatinellin;^, entirely confined to this grouj) of
islands and constituting its most distinguishin*'- feature.
Thirteen gen^a-a (comprising sixty-four species) are found
also in the other Polynesian Islands, but three genera of
Auriculid?e (Plecotrema, Pedipes, and Blauneria) are not
found in the Pacific, but inhabit — the former genus
Australia, China, BourlDon, and Cuba, the two lattcT the
West Indian Islands. Another remarkable peculiarity of
these islands is the small number of Operculata, which are
represented by only one genus and five species, while the
other Pacific Islands have twenty genera and 115 species,
or more than half the number of the Inoperculata. This
difference is so remarkable that it is worth stating in a
comparative form : —
Inoi)evculata Oporculata. AuriciiliiUr.
Sandwich Islands 332 5 9
Rest of Pacific Islands 200 llo 16
When we remember that in the West Indian Islands
the Operculata abound in a greater proportion than even
in the Pacific Islands generally, we are led to the con-
clusion that limestone, which is plentiful in both these
areas, is especially favourable to them, while the purely
volcanic rocks are especially unfavourable. The other
peculiarities of the Sandwich Islands, however, such as the
enormous preponderance of the strictly endemic Achat i-
nellinse, 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 wdien the distribution of many of the gi'oups of
mollusca Avas very different from that which n<nv ])revails.
A very interesting feature of the Sandwich group is
the extent to which the species and even the genera are
confined to separate islands. Thus the genera C'an'lia
and Catinella with eight species are peculiar to the island
of Kaui ; Bulimella, Apex, Frickella, and Blauneria. to
Oahu ; Perdicella to i\raui ; and Kburnella to Lanai.
318 ISLAND LIFE
The Rev. John T. Gulick, who has made a special study of
the Achatinellinae, 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 valley,
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 explored, 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
species of Achatinellidae, represented by 700 or 800
varieties. The most important peculiar genus, not belong-
ing 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 stretching westward, and situated on
an extensive bank with less than a thousand fathoms of
water over it, may indicate the position of a large sub-
merged island whence some portion of the Sandwich
Island fauna was derived.
Insects. — Owing to the researches of the Rev. T.
Blackburn we have now a fair knowledge of the Coleop-
terous fauna of these islands. Unfortunately some of the
most productive islands in plants — Kaui and Maui — were
very little explored, but during a residence of six years the
equally rich Oahu was well worked, and the general
character of the beetle fauna must therefore be considered
to be pretty accurately determined. Out of 428 species
collected, many being obviously recent introductions, no
1 Journal of the Linnean Society, 1873, p. 496. "On Diversity of
Evolution under one set of External Conditions," Proceedings of the
Zoological Society of London, 1873, p. 80. "On the Classification of the
AchitinellidiTB. ""
CHAP. XV THE SANDWICH ISLANDS niO
less than 352 species and 99 of the genera appear to bo
quite peculiar to the archipelago. Sixty of these species
are Carabidse, forty-two are Stapliylinida', forty are
Nitidulidse, twenty are Ptinida?, twenty aroCiodida', thirty
are Aglycyderid», forty-five are Curculionid;;e, and fourteen
are Cerambycida\ the remainder being distribute*! aumng
twenty-two other families. Many important families, such
as Gicindelidse, Scaraboiida?, Buprestid?e, and the whole of
the enormous series of the Phytophaga are either entirely
absent or are only represented by a few introduced species.
In the eight families enumerated above most of the species
belong to peculiar genera which usually contain numerous
distinct species ; and we may therefore consider these to re-
present the descendants of the most ancient immigrants into
the islands.
Two important characteristics of the Coleopterous fauna
are, the small size of the species, and the great scarcity of
individuals. Dr. Sharp, who has described many of them,^
says they are " mostly small or very minnte insects," and
that " there are few — probably it would be correct to say
absolutely none — that would strike an ordinary observer as
being beautiful." Mr. Blackburn says that it was not an
uncommon thing for him to pass a morning on the
mountains and to return home with perhaps two or three
specimens, having seen literally nothing else except the
few species that are generally abundant. He states that
he " has frequently spent an hour sweeping flower-covered
herbage, or beating branches of trees over an inverted
white umbrella without seeing the sign of a beetle of any
kind." To those who have collected in any tropical or
even temperate country on or near a continent, this
poverty of insect life must seem almost incredible ; and it
affords us a striking proof of how erroneous are those now
almost obsolete views which imputed the abundance,
variety, size, and colour of insects to the warmth and sun-
light and luxuriant vegetation of the tropics. The facts
become quite intelligible, however, if we consider tliat only
^ " IMemoirs on the C"oleoptera of the Hawaiian Islands." By the Rev. T.
Blackburn, B.A., and Dr. D. Sharp. Scicnlijic Transactions of thr hoyal
Dublin Society. Vol. III. Series II. 1885.
320 ISLAND LIFE
minute insects of certain groups could ever reach the islands
by natural means, and that these, already highly specialised
for certain defined modes of life, could only develop
slowly into slightly modified forms of the original types.
Some of the groups, however, are considered by Dr. Sharp
to be very ancient generalised forms, especially the peculiar
family Aglycyderidte, which he looks ujoon as being
" absolutely the most primitive of all the known forms of
Coleoptera, it being a synthetic form linking the isolated
Rhynchophagous series of families with the Clavicorn series.
About thirty species are known in the Hawaiian Islands,
and they exhibit much difference inter se." A few remarks
on each of the more important of the families Avill serve to
indicate their probable mode and period of introduction into
the islands.
The Carabidse consist chiefly of seven peculiar genera of
Anchomenini comprising fifty-one species, and several
endemic species of Bembidiinse. They are highly peculiar
and are all of small size, and may have originally reached
the islands in the crevices of the drift wood from N.W.
America which is still thrown on their shores, or, more
rarely, by means of a similar drift from the N.- Western
islands of the Pacific.^ It is interesting to note that
peculiar species of the same groups of Carabidse are found
in the Azores, Canaries, and St. Helena, indicating that
they possess some si3ecial facilities for transmission across
wide oceans and for establishing themselves upon oceanic
islands. The Staphylinidse present many peculiar species
of known genera. Being still more minute and usually
more ubiquitous than the Carabidse, there is no diflBculty in
accounting for their presence in the islands by the same
means of dispersal. The Nitidulida?, Ptinidse, and Ciodida^
being very small and of varied habits, either the perfect
insects, their eggs or larvae, may have been introduced
either by water or wind carriage, or through the agency of
birds. The Curculionidae, being wood bark or nut borers,
would have considerable facilities for transmission by
floating timber, fruits, or nuts ; and the eggs or larvae of the
^ See Hilclebrand's Flora of the Hawaiian Islands, Introduction, p.
xjv.
cHAr. XV THE SANDWICH ISLANDS 321
peculiar Cerambycidae must have been introduced by the
same means. The absence of so many important and
cosmopoHtan groups whose size or constitution render tliom
incapable of being thus transmitted over tlie oca, as well
as of many which seem equally well adapted as those
which are found in the islands, indicate how rare have l)een
the conditions for successful immigration; and this is still
further emphasized by the extreme specialisation of the
fauna, indicating that there has been no repeated
immigration of the same species which would tend, as in
the case of Bermuda, to preserve the originally intro-
duced forms unchanged by the effects of repeated inter-
crossing.
Vegetation of the Sctnchuich Islanch. — The flora of these
islands 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 we
fortunately have a pretty full knowledge of it, owing to
the researches of the German botanist Dr. W. Hilde-
brand.^
Considering tlieir extreme isolation, their uniform
volcanic soil, and the large proportion of the chief island
which consists of barren lava-fields, the flora of the
Sandwich Islands is extremely rich, consisting, so far as at
present known, of 844 species of flowering plants and 155
ferns. This is considerably richer than the Azores (430
Phanerogams and 39 ferns), which though less extensive
are perhaps better known, or than the Galapagns (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 explored, has rot a very much larger
number of flowering plants (935 species), while in ferns it
is barely equal.
^ Flora of the Haivaiian Islaiuh, U- W. lliMrluMiul, M.D., annot.it.-d
nn<i jmblishcd after the author's (ieatli l.y W. 1'. lliMohrand. l'^'^''.
322
ISLAND LIFE
tART II
the number of indioenoiis
The following list gives
species in each natural order.
Number of Specks in each NcUiiral Order in the Haicaiian Flora,
excluding the inb'odaccd Plants.
I 48. Gentiauacei-e (Erythnta; ... 1
... 249. Loganiaceai 7
... 4 50. Apoeynaceie 4
1 5L HyJrophyllacen.' (Xama —
... 3 allies Andes')
4.
5.
G.
7.
8.
9.
10.
11. Guttifei-ffi
12. Ternsti-ffimiaceie
13. Malvaceae
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
9'
Dicotyledons.
Kanimculacese 2
jSIenispermacete 4
Papaveraceee 1
Cruciferae 3
Capparidaceee 2
Yiolacese 8
Bixacefe 2
Pitto.sporacetc 10
Caryopliyllaceffi 23
PortulaceK 3
1
1
14
Sterculiaceffi 2
Tiliacese 1
CleraniacCcC 6
Zygopliyllacetu 1
Oxalidacese 1
Rutacero 30
Ilicinea3 1
Celastracere 1
Rlianinaccce • 7
Sapindacece 6
Anacardiacea,'
Legiimiiiosre
Rosacese
Saxifragaceiie (tree.
Droseraceit;
Haloragea?
Myrtacea; 6
31. Lytliracete 1
32.
33.
34.
35.
36.
37.
38.
39.
40.
41.
42.
43.
44.
28.
29.
30.
Onagraceaj
Cucurbitaceee
Ficoidese ....
liegoniaceie .
Umbelliferaj.
Araliaoea
Rubiacese ....
Compo.sitcie .
Lobeliaceaj .
Goodeniacese 8
Vaccinacepe 2
Epacridacese 2
Sapotaceffi ?>
45. Myrsinacea:! 5
46. Primulacete (Lysimachiii)
shrubs 6
47. Pliimbaginacetc 1
1
Oleacese 1
Solanacea3 12
Convolviilace* 14
Boraginacese 3
Scroplmlariaccie 2
Gesneviacepe 24
Myoporacese 1
Yerbenaceffi 1
Labiatee 39
Plantaginacea 2
Nyctaginacese 5
Araarantaceai 9
Phytolaccaceie 1
Polygonacere 3
Clienopodiaceie 2
Lauraceai ' 2
Thymelieaceffi 7
Santalaceai 5
Lorantliaccfe 1
Euplioibiaceco 12
Urticacea? 15
Piperaceai 20
j Monocotyledons.
I 74. Orchidacea; 3
j 75. Scitaminacew 4
j 76. Iridaceffi 1
177. Taccacese 1
: 78. Dioscoreaccffi 2
79. Liliaceee 7
80. Commeliiiaceae 1
, 81. Flagellariacese 1
I 82. Juncaceai 1
' 83. Palmaceae 3
j 84. Pandanacere 2
85. Araceae 2
j 86. Kaiadaceae 4
187. Cyperacese 47
\ 88. Gramiuaceee o7
! VasculaPv Cryptooam.s,
! Ferns 136
j Lycopodiaceffi 17
I Rliizocarpese 2
o'J,
53.
54.
55.
56.
57.
58.
59.
60.
61.
62.
63.
64.
65.
&Q.
67.
QS.
69.
70.
71.
72.
73.
CHAP. \'v THK SAyr)^VT^lT ISLAND.^ .12.3
Peculiar Features of the Flora. — This rich insular Hura is
wonderfully peculiar, for if we deduct 115 sjecics, which
are believed to have been introduced by m.iu. there
remain 705 species of flowering plants of which r)74, or
more than four-fifths, are quite peculiar to the islands.
There are no less than 38 peculiar genera out of a total of
265 and these 38 genera comprise 254 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 the Hawaiian species of
Lobelia which are woody shrubs either creeping or six feet
high, while a species of one of the peculiar genera (^f Lobe-
liaceffi is a tree reaching a height of fort}^ feet. Shrubby
geraniums grow^ twelve or flfteen feet high, and some
vacciniums gro"\v as epiphytes on the trunks of trees.
Violets and plantains also form tall shrubby plants, and
there are many strange arborescent compositie, as in other
oceanic islands.
The affinities of the floi'a generally are very wide
Although there are many Polynesian groups, yet Austra-
lian, New Zealand, and American forms are etpially re-
presented. Dr. Pickering notes the total absence of a large
number of families found in Southern Polynesia, such as
Dilleuiacese, Anonaceae, Olacacea?, Aurantiacea\ Guttifera\
Malpighiacea', Meliaceae, Combretacete, Rhizophoracea^,
Melastomacea?, Passifloraceae, Cunoniaceie, Jasminacea\
Acanthacea^, Myristicacea3, and Casuaracea^ as well as the
genera Clerodendron, Ficus, and epidendric orchids.
Australian aflinities are shown by the genera Exocarpus.
Cyathodes, Melicope, Pittosporum, and by a phyllodinous
Acacia. New Zealand is represented by Ascarina.
Coprosma, Actena, and several Cyperacea^ ; while America is
represented by the genera Nama, Gunnera, Pliyllostegia,
Sisyrinchium, and by a red-flowered Rubus and a yellow-
flowered Sanicula allied to Oregon species.
There is no true alpine flora on the higher summits, but
several of the temperate forms extend to a great elevation.
Thus Mr. Pickering records Vaccinium, Ranunculus, Sileno,
Gnaphalium and Geranium, as occurring above ten
V ::
S24 ISLAND LIFE tAirr it
thousand feet elevation ; while Viola, Drosera, Acsena,
Lobelia, Edwardsia, Dodonsea, Lycopodium, and many
ComjDositse, range above six thousand feet. Yaceinium
and Silene are very interesting, as they are almost peculiar
to the North Temperate zone : while many plants allied
to Antarctic species are found in the bogs of the high
plateaux.
The proportionate abundance of the different families
in this 'interesting flora is as follows : —
1. Compositse 70 species. '\ 1 2. UrticaeecC 15 species.
2. Lobeliacese 58 ,, 13. Malvaceae 14 ,,
3. Graminaceie 57 ., 14. Convolvulaceft; 14
4. Rubiacese 49 ., 15. Araliacesc 12
5. Cyperaceffi 47 ;, 16. Solanacese 12
6. Labiatse 3P .. 17 Euphorbiaccon 12 ,,
7. Rutacese ^-) j, 18. Pittosporaceee 10 .,
8. Gesneriaceffi 24 ., 19. Aniarantacefe 9 .,
9. Caryophyllaceas 23 ,. 20. Yiolace?e 8 ,,
10. Leguminosse 21 ,, 21. Goodeniacepe S ],
11. Piperaceaj 20 ,,
Nine other orders, Geraniacese, Khamnacece, Rosaceae,
Myrtacese, Primulacese, Loganiacese, Liliacese, Thymelacese,
and Cucurbitacese, have six or seven species each ; and
among the more important orders which have less than
five species eAch are Ranunculacea;, Cruciferse, Yaccinaceae,
Apocynacea^, Boraginacese, Scrophulariaceae, Polygonaceae,
Orchidacese, and Juncaceae. The most remarkable feature
here is the great abundance of Lobeliacese, a character of
the flora which is probably unique ; while the superiority
of Labiata3 to Leguminosse and the scarcity of Rosacea^
and Orchidacete are also very unusual. Composites, as in
most temperate floras, stand at the head of the list, and it
will be interesting to note the affinities which they indi-
cate. Omitting eleven species which are cosmopolitan,
and have no doubt entered with civilised man, there re-
main nineteen genera and seventy species of Compositae
in the islands. >Sixty-one of the species are peculiar, as
are eight of the genera; while the genus Lipochaeta Avith
eleven species is only known elsewhere in the Galapagos,
where a single species occurs. AVe may therefore consider
that nine out of the nineteen genera of Hawaiian Com-
mrAp. XV THi: sAxnwicir isr,AXi)s f.iir,
posit;(' aiv vrally coiitiii»'(l to tlic /Mvliipda-. .. Tli.' irl.i-
tions of the peculiar utMitra aii-.i s)K.'fi(\s are indicated in
the following table. ^
^ljtinUi'8 of Ituicailan Cuinposiks.
No. of
Peculiar Genera. Snecies. External Afliuitles of tli-- (Jem.s.
liemya "1 Very peculiar. Allied to the North American
genus Griiulelia.
Tetramolobium ... 7 South Temperate Amcriia :in<l Au.strali;k.
Lipochteta H Allied to American genera.
» 'ampylotha'ca ... IJ With Tropiral American spccie.s of IW.Jens and
Coreopsi.-'.
Argyroxi[)hinni ... '1 With the Me.viean Madieie.
Wilkesia 2 Same affinities.
Dubantia •! With the i\Iexican riaillardclla.
Raillardia \~ Same affinities.
Hesperomannia... 'l Allied to Stifl'tia and Wunderli.hia <.!' Dra/il.
Peculiar Species.
Lagenophnra 1 Australia, Xcw Zealand. Antarctic AiiK-rica. Fiji
Islands.
fleneeio 2 Universally distributed.
Artemisia 2 * Xortli Tempei'ate Regions.
The great preponderance of American relations in the
Composite, as above indicated, is very interesting and
suggestive, since the Composita' of Tahiti and tlie other
Pacific Islands are allied to Malaysian types. It is liere
that we meet with some of the most isolated and remark-
able forms, implying great antiquity ; and when we con-
sider the enormous extent and world-wide distribution ()f
this order (comprising about ten thousand species),^ its
distinctness from all others, the great specialisation of its
flowers to attract insects, and of its seeds for dispersal l>y
wind and other means, we can hardly doubt that its origin
dates back to a very remote epoch. We may theretore
look upon the Composita? as representing the most ancient
portion of the existing flora of the Sandwich Islands,
carrying us back to a very remote period when the faedi-
ties'^for communication with America were greater than
they are now. This may be indicated by the two det'})
submarine banks in the North Pacific, between the Sand-
wich Islands and San Francisco, which, from an ocean th.or
1 These are obtained from Hildebrand's Flora supplemented by Mr.
Bcnthani's paper in the Journal of thr Linnran Socidy.
326 ISLAND LIFE
nearly 3,000 fathoms deep, rise up to within a few hun-
dred fathoms of the surface, and seem to indicate the sub-
sidence of two islands, each about as large as Hawaii.
The plants of North Temperate affinity may be nearly as
old, but these may have been derived from Northern Asia
by way of Japan and the extensive line of shoals which
run north-westward from the Sandwich Islands, as shown
on our map. Those which exhibit Polynesian or Australian
affinities, consisting for the most part of less highly modi-
fied species, usually of the same genera, may have had
their origin at a later, though still somewhat remote
period, Avhen large islands, indicated by the extensive
shoals to the south and south-west, offered facilities for the
transmission of plants from the tropical portions of the
Pacific Ocean.
It is in the smaller and most woody islands in the
westerly portion of the group, especially in Kauai and
Oahu, that the greatest number and variety of plants are
found and the largest proportion of peculiar species and
genera. These are believed to form the oldest portion of
the group, the volcanic activity having ceased and allowed
a luxuriant vegetation more completely to cover the
islands, while in the larger and much newer islands of
Hawaii and Maui the surface is more barren and the
vegetation comparatively monotonous. Thus while twelve
of the arborescent Lobeliacese have been found on Hawaii
no less than seventeen occur on the much smaller Oahu,
which has even a genus of these plants confined
to it.
It is interesting to note that while the non-pecuHar
genera of flowering plants have little more than two
species to a genus, the endemic genera average six and
three-quarter species to a genus. These may be con-
sidered to represent the earliest immigrants which became
firmly estabhshed in the comparatively unoccupied islands,
and have gradually become modified into such complete
harmony with their new conditions that they have de-
veloped into many diverging forms adapting them to
different Jiahitats. The following is a hst of the peculiar
genera with the number of species in each.
CHAP. XV
THE SAXDWK'II ISLANDS
32;
PccuJiat' Hauaiian fkaera of Fluicciiiirj I'lants.
Gems. No. of Si ccii-s. Natural Onlir.
1. Isodendriou •"'> Violacoic,
2. Scliiedea (seeds rugose or iniivicate) 17 ''arvophyUacen'.
3. Alsiuidendron 1 ,,
4. Pelea -" H\itaoe;i'.
5. Platydesrrm l ,,
G. Mahoe 1 Sai-iiidaeeu'.
7. Hroussai.sia - Saxifragacfu-.
8. Hildebrandia 1 Be^^onracea.-.
9. Cheirodendron (fleshy fniit 2 Arali;i.ry..
10. Pterotropia (succulent o
U. Triplasandra (drupe) -J
12. Xadua (small, flat, winged seeds) ]•' Hul.iaccj'.
i;3. Gouldia (berry^ •''
14. Bobea(drupe) ^^
15. Straussia (drupe I ')
16. Reniya..... 2 CuinpusitiP.
17. Tetramolobiuiii 7
18. Lipoch;eta 11
19. Campylotheca 12
20. Argvroxijiliium 2
21. Wilkesia 2
22. Dubautia •>
23. Raillardia 12
24. Hesperonianuin 2 ,,
25. Briglianiia 1 T/)beliace:e.
26. Cleiinontianicrrv 11
27. Rollaudia "i
28. Delis.sea 7
29. Cvanea :^'>
30. Labordea "-^ Loganiac-ea\
31. Xothocestrum 1 Solaiiaoea-.
32. Haj.lostacliys (nucules dry) ••'> Labiata-.
33. I'hyllostegia (nucules fleshy^ l'> .,
34. Stenogvne (nucules fleshy ) I'-I ,,
35. Xototrichium '"> Aniarantaceie.
36. Charpentiera 2 ,,
37. Touchardia 1 Irticacea".
38. Neraudia -
Total 254 .species.
The great iDreponderanca of tlie two orders Compositae
and Lobeliacoa? are what first strike us in this hst. In tlie
former case the fiiciHties for wind-dispersal afforded by the
structure of so many of the seeds ren(k^r it com])nra-
tively easy to account for their having renclied the isbnds
at an early period. The Lobelias, judging from Hilde-
brand's descriptions, may have been transported in several
328 ISLAND LIFE
different ways. Most of tlie endemic genera are berry-
bearers and thus offer the means of dispersal by fruit-
eating birds. The endemic species of the genus Lobeha
have sometimes very minute seeds, which might be carried
long distances by wind, while other species, especially
Lobelia gaudichaudii, have a " hard, almost woody capsule
which opens late," apparently well adapted for floating
long distances. Afterwards "the calycine covering
withers away, leaving a fenestrate woody network '' en-
closing the capsule, and the seeds themselves are '' com-
pressed, reniform, or orbicula,r, and margined," and thus
of a form well adapted to be carried to great heights and
distances by gales or hurricanes.
In the other orders which jDresent several endemic
genera indications of the mode of transit to the islands
are afforded us. The Araliacese are said to have fleshy
fruits or drupes more or less succulent. The Rubiaceas
have usually berries or drupes, while one genus, Kadua,
has " small, flat, winged seeds." The two largest genera
of the Labiata3 are said to have " fleshy nucules," which
would no doubt be swallowed by birds.^
Antiqitity of the Hcmaiian Fauna and Flora. — The
great antiquity implied by the peculiarities of the fauna
and flora, 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 v/ould soon occui^y much of the surface, and
become specially modified in accordance with the condi-
tions of the locality, and these would serve as a barrier
against the intrusion of many forms w^hich at a later
^ Among the curious features of the Hawaiian flora is the extraordinary
development of what are usually herbaceous plants into shrubs or trees.
Three species of Yiola are shrubs from three to five feet high. A shrubby
Silene is nearly as tall ; and an allied endemic genus, Schiedea, has
numerous shrubby species. Geranium arhorcum is sometimes twelve feet
high. The endemic Compositte are mostly shrubs, while several are trees
reaching twenty or thirty feet in height. * The numerous Lobeliacese, all
endemic, are mostly shrubs or trees, often resembling palms or yuccas
in habit, and sometimes twenty-five or thirty feet high. The only native
genus of Primulacess — Lysimachia — consists mainly of shrubs ; and even r.
plantain has a woody stem sometimes six feet high.
CHAP. XV OCEANIC ISLANDS 329
period spread over Polynesia. The extreme remoteness
of the islands, and the jirobability that they have always
been more isolated than those of the Central Pacific,
would also necessarily result in an imperfect and frag-
mentary representation of the flora of surrounding lands.
Concluding Observations on the Fauna and Flora of the
Sandwich Islands. — The indications thus afforded by a
study of the flora seem to accord well with what we know
of the fauna of the islands. Plants having so much
oreater facilities for dispersal than animals, and also having
oreater specific longevity and greater powers of endurance
under adverse conditions, exhibit in a considerable degree
the influence of the primitive state of the islands and their
surroundings ; while members of the animal world, passing
across the sea with greater difficulty and subject to exter-
mination by a variety of adverse conditions, retain much
more of the impress of a recent state of things, with per-
haps here and there an indication of that ancient appr(iach
to America so clearly shown in the Composita^ and some
other portions of the flora.
General Remarks ox Oceanic Islands.
We have now reviewed the main features presented by
the assemblages of organic forms which characterise the
more important and best known of the Oceanic Islands.
They all agree in the total absence of indigenous mam-
malia and amphibia, wdule their reptiles, when they possess
any, do not exhibit indications of extreme isolation and
antiquity. Their birds and insects present just that
amount*^ of specialisation and diversity from continental
forms which may be well explained by the known nieans
of dispersal 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 have
occurred during the Tertiary epoch, and preserve to us in
highly specialised and archaic forms some record of the
prTmeval immigration by which the islands were originally
330 ISLAND LIFE part ii
clothed with vegetation. But in every case the series
of forms of life in these islands is scanty and im-
perfect as compared with far less favourable continental
areas, and no one of them 2:>resents such 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 imjDortant to note that none of these
oceanic archipelagoes present us with a single type which
we may sujjpose to have been preserved from Mesozoic
times ; and this fact, 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 otherwise — had sea
and land changed place repeatedly as was once supposed —
had our deepest oceans been the seat of great continents
while the site of our present continents was occui^ied by
an oceanic abyss — is it possible to imagine that no frag-
ments of such 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 volcanic islands
or extinct submarine volcanoes), and that their productions
are all more or less clearly related to the existing inhabit-
ants of the nearest continents, are hardly consistent with
any other theory than the permanence of our 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.
CHAPTER XVT
CONTINENTAL ISLANDS OF REf'ENT ORIOIN : ORKAT
BRITAIN
C'liaracteristic Features of Rcoent Continental Islands— Recent riiysiial
Changes of the liiitish Isles— Proofs of Former Elevation— SubniergeJ
Forests — Buried River Channels — Time of Last Union with the Conti-
nent— Why Britain is poor in Species— Peculiar British Birds— Fresli-
water Fishes— Cause of Great Speciality in Fishes —Peculiar British
Insects— Lepidoptera Confined to the British Isles— Peculiarities of the
Isle of Man — Lepidoptera — Coleoptera confined to the Britisli Isk-s —
Triehoptera Peculiar to the British Isles— Land and Freshwati-r Shells
—Peculiarities of the Biitish Flora— Peculiarities of the Irish Flora—
Peculiar British Mosses and Hepatica^— Concluding Remarks on tlie
Peculiarities 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 subsidence of the intervening land at a iH'iiod
which, geologically, must be considered recent. Sucli
islands are always still connected 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 ut
the mainland; while their entire flora and fauna is
characterised either by the total absence or comparative
scarcity of those endemic or peculiar species and genera
which are so striking a feature of almost all oceanic
islands. Such islands will, of course, difler from each
332 ISLAND LIFE
other in size, in antiquity, and in the richness of their
respective faunas, as well as in their distance from the
parent land and the facilities for intercommunication with
it ; and these diversities of conditions will manifest them-
selves 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 had a very limited area of distribution, and
this area may be wholly oralmost wholly contained in the
separated portion or island, to which it will henceforth be
peculiar. Even when the area occupied by a species is
pretty equally divided at the time of separation between
the island and the continent, it may happen that it will
become extinct on the latter, while it may survive 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
continent, while they may flourish under the more favour-
able insular conditions. On the other hand, when a
species continues to exist in both areas, it may on the
island be subjected to some modifications by the altered
conditions, and may thus come to present characters Avhich
differentiate it from its continental allies and constitute it
a new species. We shall in the course of our survey meet
with cases illustrative of both these processes.
The best examples of recent continental islands are
Great Britain and Ireland, Japan, Formosa, and the larger
Malay Islands, especially Borneo, Java, and Celebes ; and
as each of these presents special features of interest, we
will give a short outHne of their zoology and past history
in relation to that of the continents from which they have
recently been separated, commencing with our own islands,
to which the present chapter will be devoted.
Bcccnt I'liysical Changes in the British Isles. — Great
Britain is perhaps the most typical example of a large and
recent continental island now to be found upon the globe.
It is^ joined to the Continent by a shallow bank which
extends from Denmark to the Bay of Biscay, the 100
fathom line from these extreme points receding from th«
fH:\r: xvi
THE BRITISH ISLES
333
coasts so as to include the whole of the British Isles and
about fifty miles beyond them to the westward. (Sec Ma]).)
MAP SHOWING THE SHALLOW BANK CONNECTING THE BRITISH ISLFS WITH THK CONTINENT .
The light tint iiulicatcs a depth of less than 100 fatlioms.
'. ■- The figures show, the depth in fathoms.
. The narrow channel between Norway and Denmark is •2,r>^0 feet doo]».
Beyond this line the sea deepens rapid I v to the 500 and
1,000 fathom lines, the distance between 100 and 1,000
ISLAND LIFE i-art ii
fathoms being from twenty to fifty miles, except where
there is a great outward curve to include the Porcupine
Bank 1^0 miles west of Galway, and to the north-west of
Caithness where a narrow ridge less than 500 fathoms
below the surface joins the extensive bank under 800
fathoms, on which are situated the Faroe Islands and
Iceland, and which stretches across to Greenland. In the
North Channel between Ireland and Scotland, and in the
Minch between the outer Hebrides and Skye, are a series
of hollows in the sea-bottom from 100 to 150 fathoms
deep. These correspond exactly to the points between the
opposing highlands where the greatest accumulations of ice
would necessarily occur during the glacial epoch, and they
may well be termed submarine lakes, of exactly the same
nature as those which occur in similar positions on land.
Proofs of Foriiier Elevation — Suhmcrged Forests. — What
renders Britain particularly instructive as an example of a
recent continental island is the amount of direct evidence
that exists, of several distinct kinds, showing that the land
has been sufficiently elevated (or the sea depressed) to
unite it with the Continent, — and this at a very recent
period. The first class of evidence is the existence, all
round our coasts, of the remains of submarine forests often
extending far below the present low-water mark. Such
are the submerged forests near Torquay in Devonshire, and
near Falmouth in Cornwall, both containing stumps of
trees in their natural position rooted in the soil, with
deposits of peat, branches, and nuts, and often with
remains of insects and other land animals. These occur
in very different conditions and situations, and some have
been explained by changes in the height of the tide, or by
pebble banks shutting out the tidal waters from estuaries ;
but there are numerous examples to which such hypotheses
cannot apply, and which can only be explained by an
actual subsidence of the land (or rise of the sea-level) since
the trees grew.
We cannot give a better idea of these forests than by
quoting the following account by Mr. Pengelly of a visit to
one which had been exposed by a violent storm on the
coast of Devonshire, at Blackpool near Dartmouth :—
CHAP. XVI THE BRITISH ISLES 33;
" We were so fortunate as to reach the beach at spring-
tide low-water, and to lind, admirably exposed, by far the
finest example of a submerged forest which I liave ever
seen. It occupied a rectangular area, extending from the
small river or stream at the western end of the inlet, about
one furlong eastward ; and from the low-water line thirty
yards up the strand. The lower or seaward portion of the
forest area, occupying about two-thirds of its entire
breadth, consisted of a brow^nish drab-coLjured clay, which
was crowded with vegetable debris, such as small twigs,
leaves, and nuts. There w^ere also numerous prostrate
trunks and branches of trees, lying partly imbedded in the
clay, without anything like a prevalent direction. The
trunks varied from six inches to upwards of two feet in
diameter. Much of the w^ood was found to have a reddish
or bright pink hue, when fresh surfaces w^ere 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 effected
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. Hazelnuts 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 w^as not above the level of high water. There is
satisfactory evidence that in Torbny it wa.s not le.^s than
forty feet, and that in Falmouth Harbour it amounted to
at least sixty-seven feet." ^
^ Gcolofjical Jlngaziiii; 1870, 1'. l;''-'^-
ISLAND LIFE I'ART it
- On the coast of theBristol Channel similar deposits occur,
as well as along much of the coast of Wales and in Holy-
head Harbour. 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 antlers of the reindeer were found,
the remains of animals which had been devoured there by
bears and hysenas ; facts which can only be explained by
the existence of some extent of dry land stretching sea-
ward from the present cliffs, but since submerged and
washed away. This plain may have continued down to
very recent times, since the whole of the Bristol Channel
to beyond Lundy Island is under twenty-five fathoms deep.
In the east of England we have a similar forest-bed at
Cromer in Norfolk ; and in the north of Holland an old
land surface has been found fifty-six feet below high-water
mark.
Baried River Channels. — Still more remarkable are the
buried river channels which have been traced on many
parts of our coasts. In order to facilitate the study of the
glacial deposits of Scotland, Dr. James Croll obtained the
details of about 250 bores put down in all parts of the
mining districts of Scotland for the purpose of discovering
minerals.! These revealed the interesting fact that there
are ancient valleys and river channels at depths of from
100 to 260 feet below the present sea-level. These 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 up and
hidden by boulder clay, "^drift, and sands, that there is no
indication of their presence on the surface, which often
consists of mounds or low hills more . than 100 feet high.
One -of these old valleys connects the Clyde- near Dum^
barton with the Forth at Grangemouth, and appears to
have contained two streams flowing in opposite directions
from a watershed about midway at Kilsith. At Grange -
^ TranmHions of the Edinburgh Geological Society, Vol. I. p. 330.
CHAP. XVI TIIK r.KITISlI Isr.KS 337
mouth the old channel is 2(30 feet below the sea-level
The watershed at Kilsith is now IGU feet above the sea,
the old valley bottom being 120 feet deep or forty feet
above the sea. In some places tlic old valley was a
ravine with precipitous rocky walls, which have* been
found in mining excavations. Sir A.Geikie, who has him-
self discovered many similar buried valleys, is of opinion
that "they unquestionably belong to the period of the
boulder clay."
We have here a clear proof that, when thcso rivers
were formed, the land must have stood in relation to the
sea at Imst 260 feet higher than it does now, and ])n-)l)ably
much more ; and this is sufficient to join England to the
continent. Supporting this evidence, we have freshwater
or littoral shells found at great depths off our coasts. Mr.
Godwin Austen records the dredging up of a freshwater
shell (Ftiio 2^^<^^ori(m) off the mouth of the English
Channel between the fifty fjxthom and TOO fathom lines,
while in the same locality gravel banks with littoral sliells
now lie under sixty or seventy fathoms water.^ More
recently Mr. Gwyn Jeffreys has recorded the discovery of
eight species of fossil arctic shells off the Shetland Isles
in about ninety fathoms Avater, all being characteristic
shallow water species, so that their association at this
o-reat depth is a distinct indication of considerable sub-
sidence.-
Time of Last Union with the Gontincnt. — 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 the greatest development of th.' ice, but
probably before the cold epoch had wholly passed awav.
But if so recent, we should naturally expect our land still
1 Quarterly Journal of Geoloijical Society, 1850, y. '.">.
- British Association^ R'-port, Dnii«U't*. 1S«37. p. -1:^1.
3S8 ISLAND LIFE
to show an almost perfect community 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 organised animals are, with but few exceptions,
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 owing to favourable insular conditions,
or by slight modifications having been caused by these
conditions resulting in a local race, sub-species, or species.
Why Britain is Foot in Species. — The former union of
our islands with the continent, is not, however, the only
recent change they have undergone. There have been
partial submergences to the depth of from one hundred to
perhaps three hundred feet over a large part of our country ;
while during the period of maximum glaciation the whole
area north of the Thames was buried in snow and ice. Even
the south of England must have suffered the rigour of an
almost arctic climate, since Mr. Clement Reid has shown that
floating ice brought granite blocks from the Channel Islands
to the coast of Sussex. Such conditions must have almost
exterminated our preexisting fauna and flora, and it was
only during the subsequent union of Britain with the con-
tinent that the bulk of existing animals and plants could
have entered our islands. We know that just before and
during the glacial period we possessed a fauna almost or
quite identical with that of adjacent parts of the continent
and equally rich in species. The glaciation and sub-
mergence destroyed much of this fauna ; and the perman-
ent change of climate 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. When England
became continental, these entered our country ; but
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 without the number of species which
our favourable climate and varied surface entitle us to.
CHAP. XVI THE BKITISIJ LSl.HS 389
To this cause we must impute our comparati\e poverty
in mammalia and reptiles — more marked in tlie latter
than the former, owing to their lower vital activity and
smaller powers of dispersal. Germany, for example,
possesses nearly ninety species of land niainmalia, and
even Scandinavia about sixty, while Britain has only
forty, and Ireland only twenty-two. The depth of the
Irish Sea being somewhat greater than that of tlie
German Ocean, the connecting land would there probably
be of small extent and of less duration, thus offering an
additional barrier to migration, whence has arisen the
comparative zoological poverty of Ireland. This poverty
attains its maximum in the reptiles, as shown by the
following figures : —
Belgium has 22 species of reptiles and ainiilii1»iu.
Britain ,, 13
Ireland ,,1 ,, m •»
Where the power of flight existed, and thus the period
of migration was prolonged, the difference is less marked ;
so that Ireland has seven bats to twelve in Britain, and
about 110 as against 130 land-birds.
Plants, which have considerable facilities for passnig
over the sea, are somewhat intermediate in proportionate
numbers, there being about 970 flowering plants and ferns
in Ireland to 1,425 in Great Britain,— or almost exactly
two-thirds, a proportion intermediate between that pre-
sented by the birds and the mammalia.
I'ccuHar British Birds— -Amowg our native mammalia,
reptiles, 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
different, since some of our species, in particular our
coal-tit and long-tailed tit, present well-marked differences
of colour as compared with continental specimens; and
in Mr. Dresser's work on the Birds of Europr they are
considered to be distinct species, while Professor Newton,
in his new edition of Yarrell's British Birds, does not
consider the difference to be sufficiently great or suffi-
ciently constant to warrant this, and therefore classes
Z 2
340 ISLAND LIFE
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 scoticus),
-which abounds in Scotland, Ireland, the north of England,
and Wales, and is very distinct from any continental
species, although closely allied to the willow grouse of
Scandinavia. This latter species resembles 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 Avinter
than in summer. We have here therefore a most inter-
esting example of an insular form in our own country;
but it is difficult to determine how it originated. On the
one hand, it may be an old continental species which
during the glacial epoch found a refuge here when driven
from its native haunts by the advancing ice ; or, on the
other hand, it may be a descendant of the Northern
willow grouse, which has lost its power of turning white
in winter owing to its long residence in the lowlands of an
island where there is little permanent snow, and where
assimilation in colour to the heather among which it lurks
is at all times its best protection. In either case it is
equally interesting, as the one large and handsome bird
which is peculiar to our islands notwithstanding their
recent separation from the continent.
The following is a list of the birds now held to be
peculiar to the British Isles : —
L Parus ater, sub. s-p. bpjtannicus Closely allied to P. ater of tlie
continent ; a local race or
sub-species.
2. Acredula caudata, m&. 5^^. ROSEA Allied to A. caudata of the
continent.
3, Lagopus scoTicus Allied to X, alius of Scandin-
avia, a distinct species.
Freshwater Fishes. — Although the productions of fresh
waters have generally, as Mr. Darwin has shown, a wide
range, fishes appear to form an exception, many of them
being extremely limited in distribution. Some are confined
to particular river valleys or even to single rivers, others
inhabit the lakes of a limited district only, while some are
THAP, XVI
THE liKlTISH ISLES
.•^•Jl
coiitiiiL'd to single lakes, often ofsiuall an-.i. and tlu'se latter
ofter examples of the most restricted distribution ui' anv
organisms whatever. Cases of this kind arc found in «jur
own islands, and deserve our especial attention. It lias
long been known tliat some of our lakes possessed peculiar
species of trout and charr, but how far these were
unknown on the continent, and how many of those in
different parts of our islands were really distinct, had not
been ascertained till Dr. Glinther, so well known for his
extensive knowledge of the species of fishes, obtained
numerous specimens from every part of the country, and
by comparison with all known continental species deter-
mined their specific differences. The striking and
unexpected result has thus been attained, that no less
than fifteen Avell-marked species of freshwater fishes arc
altogether peculiar to the British Islands. The following
is the list, with their English names and localities : — '
Freshwater Fishes peculiar lo the British Isles.
Latin Name.
1. Salmo BHACHYPUMA
GALL1VEX8IS
OliCADENSlS.
FEROX
8TOMACHICUS
NIGKIPINNIS
LEVENENSIS,
Peri. SI I
AVlLLUGHBlI
English Name. Locality.
Short-headed salmon Firth of Forth, Twct'd,
Ouso.
(lahvay sea-trout Gahvay, AW'st Ireland.
Loch Stennis trout... ! Lakes of Orkney.
Great lake- trout Larger lakes of Scotland.
I Ireland, the N. of
Englantl, and "Wales.
Gillaroo trout | Lakes of Ireland.
Mountain lochs of Wahs
and Scotland.
Loch Levcn, Loch Ti<>-
mond, Windermere.
Llanberris lakes, N.
Wales.
Lake "Windermere and
others in X. of En^'-
land, and Lake Brui-
ach in Scotland.
Killin lake in Inverness-
,-hire.
Lough Eske and Lough
Dan, Ireland.
Lough ^lehin, Leitrim,
N.W. Ireland.
Black-fumed front
Loch Leven Trout
Welsh charr
Windermere charr
KiLi.iNENSis ! Loch Killin charr
C'oLii I Cole's charr
(Ji:avi I Gray's charr
' The list of names was furnished to me by Dr. Giinthcr, and I hav.-
added the localities from the papers containing the original descriptions,
and from Dr. Ilaughton's British Fresh irater Fish's.
342 ISLAN^D LIFE
Latin Name. English Nai-.e. Locality.
13. CoREGONUS CLUPE- The gwyniad,
oiDES Schelly
Loch Lomond, UUes-
water, Derwentwater,
Haweswater, and Bala
14. ,, VANDESlus The vendace ^ Loch Maben, Dunifries-
' I shire.
15. ,, POLLAN ... The pollan j Lough Neagh and Lough
I I Earne, X. of Ireland.
These fifteen peculiar fishes differ from each other and
from all British and continental species, not in colour
only, but in such important structural characters as the
number and size of the scales, form and size of the fins,
and the form or proportions of the head, body, or tail.
Some of them, like >S'. killincnsis and the Coregoni are in
fact, as Dr. Giinther assures me, just as good and distinct
species as any other recognised 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 only one of the peculiar British species
extends to Ireland, v/hich has no less than five species
altogether peculiar to it. If the species of our own two
islands are thus distinct, wdiat reason have we for believing
that they will be otherwise than distinct from those of
Scandinavia ? At all events, with the amount of evidence
we already jDossess of the very restricted ranges of many of
our species, w^e must certainly hold them to be peculiar till
they have been proved to be otherwise.
The great speciality of the Irish fislies is very interesting,
because it is just what we should expect on the theory of
evolution. In Ireland the two main causes of specific
change — isolation and altered conditions — are each more
powerful than in Britain. Whatever difficulty continental
fishes may have in passing over to Britain, that difficulty
will certainly be increased by the second sea passage to
Ireland ; and the latter country has been longer isolated, for
the Irish Sea with its northern and southern channels is
considera]:)ly deeper than the German Ocean and the
CHAP. XVI THE BRITISH ISLES 343
Eastern half of the English Channel, so that, when the
last subsidence occurred, Ireland would have been an
island for some length of time while England and Scotland
still formed part of the continent. Again, whatever
differences have been j^roduced by the exceptional climate
of our islands will have been greater in Ireland, where
insular conditions are at a maximum, the abundance of
moisture and the equability of temperature being far
more pronounced than in any other part of Europe.
Among the remarkable instances of limited distribution
afforded by these fishes, we have the Loch Stennis trout
confined to the little group of lakes in the mainland of
Orkney, occupying altogether an area of about ten miles
by three ; the Welsh charr confined to the Llanberris lakes,
about three miles in length ; Gray's charr confined to
Lough Melvin, about seven miles long ; while the Loch
Killin charr, known only from a small mountain lake in
Inverness-shire, and the vendace, from the equally small
lakes at Loch Maben in Scotland, are two examples of
restricted distribution which can hardly be surpassed.
Cause of Great SppciaJity in Fishes. — The reason why
fishes alone should exhibit such remarkable local modifica-
tions in lakes and islands is sufticicntly obvious. It is due
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 ample
hardly any modification of species occurred, while Avhere
these means were deficient and individuals once transported
remained isolated during a long succession of ages, their
forms and characters became so much changed as to l)ring
about what we term distinct species or even distinct 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, beciuse none have
ever been conveyed to them. Others contain several ; and
some fishes which have peculiarities of constitution or habits
which render their transmission somewhat less difficult occur
in several lakes over a wide area of country, though only
one appears to be common to tho British and Irish lakps.
344 ISLAND LIFE
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 some-
times 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 course of thousands of
years, and the eggs of fishes may have been carried with
even greater ease. Again we may well suppose 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 rising over low watersheds, by elevations of the land
changing lines of drainage, or by ice blocking up valleys
and compelling the streams to flow over watersheds 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 aftbrds 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
another, it might then retire up the streams to some of the
lakes, where alone it might find conditions favourable to
it. By a combination of the modes of migration here
indicated it is not difticult to understand 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
modified by the particular conditions of the lake in which
they have found themselves isolated.
Peculiar British Insects. — We now come to the class of
insects, and here we have much more difficulty in deter-
mining what are the actual facts, because new species are
still being 3'early discovered and considerable portions of
Europe are but imperfectly explored. It often happens
that an insect is discovered in our islands, and for some
CHAP. XV THE BRITISH ISLES .Ij;-
years Britain is its only recorded locality ; but at lengtli it
is found on some part of tlie continent, and not uiifre(|uentlv
has been all the time known there, but disguised by anotheV
name, or by being classetl as a variety uf some other
species. This has occurred so often that our best entomo-
logists have come to take it for granted that nil our
supposed peculiar British species are really natives of tlio
continent and will one day be found there; and owin*"-
to this feeling little trouble has been taken to bring
together the names of such as from time to time remain
known from this country only. The view of the probable
identity of our entire insect-fauna with that of the continent
lias been held by such well-known authorities as the late
Mr. E. C. Rye and Dr. D. Sharp for the beetles, and by
Mr. H. T. Stainton for butterflies and moths ; but as we have
already seen that among two orders of vertebrates — birds
and fishes — there are undoubtedly peculiar British species,
it seems to me that all the probabilities are in favour of there
being a much larger number of peculiar species of insects.
In every other island where some of the vertebrates arc
peculiar — as in the Azores, the Canaries, the Andaman Is-
lands, and Ceylon — the insects show an equal if not a higher
proportion of speciality, and there seems no reason what-
ever why the same law should not apply to us. Our
climate is undoubtedly very distinct from that of any i>art of
the continent, and in Scotland, Ireland, and Wales we possess
extensive tracts of wild mountainous country where a moist
uniform climate, an alpine or northern vegetation, and a
considerable amount of isolation, offer all the conditions re-
quisite for the preservation of some species which may have
become extinct elsewhere, and for the slight modification 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 our recorded peculiarities in the insect
world, for it is only by so d(ting that we can lio}>e tt»
arrive at any correct solution of the cjuestion on which there
is at present so much difterence of opinion. For the li.st
of Coleoptera with the accompanying notes I wa.s
originally indebted to the late Mr. K. C. Rye ; and Dr.
Sharp also gave me valuable information as to the recent
346 ISLAND LIFE
PART II
occurrence of some of the supposed peculiar species on the
continent. The list has now been revised by the Rev. Canon
Fowler, author of the best modern work on the British
Coleoptera, who has kindly furnished some valuable notes.
For the Lepidoptera 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 furnished 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 larvse of some of our peculiar species of
Tineina feed during the winter, which they are enabled to
do owing to our mild and insular climate, but which the
severer continental 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 omfocinerca, the lava of which mines in the leaves
of Holcus mollis and other grasses from December to
March. This species, though common everywhere with
us, extending to Scotland and Ireland, is quite unknown 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 Europe ; and the
presence of this plant in a mild and insular climate such
as ours may well be supposed to have led to the pre-
servation of some of the numerous species which are or
have been dependent on it. Since the first edition was
THAI'. XVI THE BRITISH ISLES 347
published many new British species have been discovered,
while some of the supposed peculiar species have been found
on the continent. Information as to these has been kindly
furnished by Mr. W. Warren, Mr. C. G. Barrett, Lord
Walsingham, and other students of British Lepidr.])tern.
and the first-named gentleman has also looked over the
proofs.
Mr. McLachhin has kindly furnished me with sc.mc
valuable information on certain species of Trichoptera or
Caddis flies which seem to be peculiar to our islands ; and
this completes the list of orders which have been studied
with sufficient care to afford materials for such a com-
parison. We will now give the list of peculiar British
Insects, beginning with the Lepidoptera and adding such
notes as have been supplied by the gentlemen already
referred to.
List of the Species or Varieties of Lepidoptera which, so far as at present
known, arc confined to the British Mauds. ( The figures show the dates
when the species was first described. Species added since the first edition
are marked icith an eistcrisk.)
DiURNI.
1. ToLYOMMATUs DisPAK. "The large copper." This fine insect, once
common in the fens, but now extinct owing to extensive drainage,
is generally admitted to be peculiar to our island, at all events as a
variety or local form. Its continental ally ditfcrs constantly in lining
smaller and in having smaller spots; but the dilference, though
constant, is so slight that it is now classed as a variety under th-^
name of rutilns. Our insect may therefore be stated to be a well-
marked local form of a continental species.
2. Lvcfena astrarche, var. aktaxerxes. This very distinct form is con-
' fined to Scotland and the north of England. The species of which
it is considered a variety (more generally known to English entomo-
logists as P. agestis) is found in the southern half of England, and
almost everywhere on the continent.
BOMBYCEP.
n. Lithosia complana, fa;-. SERICEA. North of England (1861 .
4. Hepialus humuli, mr. hethlandica. Shetland Islands (1SC5). A
remarkable form, in whiih the male is usually yellow and biill
instead of pure white, as in the common form, but exceedingly
variable in tint and markings,
5. Epichxoptehyx retkella. Sheerncss, Gravcsend, and other locali-
ties along the Thames (1847) ; Hayling Island, Sussex.
6. E. pulla, var. radiella. Near London, rare (1830?) ; the si.enes in
Central and Southern Europe. (Doubtfully peculiar m Mr.
Stainton's opinion. )
348 ISLAND LIFE part ii
NocTU^;.
7. Acioiiycta euphoibke, var. myric^. Scotland only (1852;. A
uielanic form of a continental species.
8. Agrotis sl'brosea. Cambridgeshire and Huntingdonshire fens,
perhaps extinct (1835). The var. subccendea is found in Finland
and Livonia.
9. Agrotis candelarum var. ASH-\vorthii. South and West (1855).
Distinct and not uncommon,
10. Luperina luteago, var. barretti. Ireland (1864).
11. Aporo]>hyla australis, var. pascuea. South of England (1830). A
variety of a species otherwise confined to South Europe.
12. Hydnecia nictitans, var. taixdris.
Geometr.e.
13. Boarmia gemmaria, var. perfumaria. Near London and elsewhere.
A large dark variety of a common species.
14. *B. repandata, var. sodorensium. Outer Hebrides.
15. *Emmelesia albulata. var. hebridium. Outer Hebrides.
16. *E. albulata, vrtr. thules. Shetland Islands.
17. *Melanippe montanata, va7'. shetlandica, Shetland Islands,
18. *^r. sociata, var. obscurata. Outer Hebrides. A dark form.
19. Cidaria albulata, rar. griseata. East of England (1835), A vaiiety
of a species otherwise confined to Central and Southern Europe,
20. Eupithecia CONSTRICTATA, Widely Spread, but local (1835), Larva
on thyme.
21. *E. satyrata, var. cttrzoni. X. Scotland,
22. *E. nanata va7\ curzoni. Shetland Islands.
Pyralidina,
23. Aglossa pingninalis, var. streatfieldi, Mendip Hills (1830), A
remarkable variety of the common ' ' tabby. "
24. *Scoparia cembrre, var. .scoTiCA. Scotland (1872).
25. "Myelois ceratoniaj, var. pryerella. Xorth London (1871).
26. ■■•Howoeosonia nimlsella, var. saxicola. England, Scotland, Isle of
Man (1871).
27. 'Epischnia bankesiella. Isle of Portland (1888).
TORTRICINA,
28. Aphelia NiGROYiTTAyA. Scotland (1852\ A local form of the
generally distributed A. JaiKcolana.
29. C4RAPH0LITA PARVULAXA, Isle of Wight (1858), Rare, A distinct
species,
30. CoNCHYLis erigeraxa. Soutli-east of England (1866).
31. *Brachyt^nia woodiana. Herefordshire (1882).
32. *Eupcecilia angustana, var. thuleana. Shetland Islands,
33. *ToRTR]x DOXELAXA. Councmara, Ireland (1890).
TlXEIXA.
34. TiXEA COCHYLIDELLA, Sanderstead, near Croydon (1854), Unique !
35. AcROLEPiA BETULiETELLA, Yorkshire and Durham (1840). Rare.
36. Argyresthia semifusca, North and West of England (1829),
Rather scarce, A distinct species,
37. Gelelhia DivisELLA, A fen insect (1856). Rare,
CHAP. XVI.
lUUTISlI ISLES 349
38. G. CELERELLA. West of Eiifilaiul (1854). A doubtful spocii's.
39. *G. TETRAGONELLA. Yorkshire. Norfolk, Salt marslies.
40. ^'G. sPARsiciLlELLA. Pembroke,
41. *G. I'LANTAGINELLA. A salt-uiarsli species.
42. G. OcEi.LATELLA (Barrett nee Staiutou). Bred from Beta niaritimd.
ycvj distinct.
43. BnYOTiiOPHA roLiTEi.r.A. Moors of North of England. Norfolk (18ri4).
44. *B. poRTLANDiCELLA. Isle of Portland (1890;.
45. LlTA FKATEiiNELLA, Widely Scattered (1831\ Larva feeds on shoots
of Stellaria uliginosa in spring.
46. L. BLAKPULELLA. Kent.
47. AxACAMPSis siucoMELLA, North and West England (1854i.
Perhaps a melanic variety of the more widely spread A. famioh-ila.
48. A, iMMAcn.ATELLA, AVcst Wi.'khani (1834 . rnirpie ! A distinct
species,
49. *(EC0PHOP.A WOOUIELLA i
50. Glyphipteryx ci.ADiELLA. Eastern Couuties (18591 Abundant.
51. G. scK(ENicoLELLA. In Several localities (1859).
52. Gracilaria stramixeella. (1850). On birch. P.-rhaps a local
form of G. clongdla, found on alder.
53. Ormx loganetj.a'. Scotland (1848). Abundant, and a distinct
species.
54. 0. UEVOKIELLA. In Devonshire (1854). Unique !
55. CoLEOPHORA SAxrRATELLA. South of England (1850). Abundant on
broom.
56. ('. INFLAT.E. South and East of England. On Silene inflata. \ con-
tinental.
57. C. SQUAMOSELLA. Surrcv (1856). Very rare, but an obscure species.
58. C. RALiNELLA. On S^a-coast (1859). Abundant.
59. *C. POTENTILL-E. South of England.
60. *C. ADJUNCTELLA. Essex Salt marshes. ? Lancashire (1882).
61. *C. LIMOXIELLA. Isle of Wight. Yee^'i on Stat iccUmonium.
62. Elachista flavicomella. Dublin (1856). Excessively rare, two
specimens only known.
63. *E. sciRPi. Wales and Sussex. Salt marshes.
64. E. CONSORTELLA. Scotland (1854). A dou))ti'ul species.
65. E. MEGERLELLA. Widely distributed (1854\ Oonmion. Larva
feeds in grass during winter and early spring.
Q>^. E. OBLIQUELLA. Near London (1854). Unique !
67. E. TRISERIATELLA. South of England ^854 . Very local: an
obscure species.
68. *TiXAGMA BETUL.E. East Dorsct (1891).
69. LiTHOCOLLETis NiGREscENTELLA. Northumberland (1850\ Karc :
a dark form of X. Brevdella, which is widely distributed.
70. L. ANDEKID.*:. Sussex. Dorset (1886).
71. L. IRRADIELI.A. North Britain (1854). A northern form of tho
more southern and wide-spread L. Jautt:Ua.
72. L. TRIGUTTELLA. San lerstcad, near Croydon (1848\ rniqui' ! very
peculiar.
73. L. I'LICICOLELLA. In a f.'W widespread localities (1854). A peculiar
form.
71. L. lALEUONiELLA. North Britain (1854\ A local variety ot tlio
more widespread L. i-oniJifoliella.
350 ISLAND LIFE
75. L. DUNNINGIELLA. Xortli of England (1852\ A somewhat doubt-
ful species,
76. BuccuLATKix DEMARYELLA. Widely distributed (1848). Rather
common.
77. Trifurcula squamatella. South of England (1854). A doubtful
species.
78. Nepticula ignobiliella. Widely scattered (1854). On hawthorn,
not common. 1 on continent.
79. X. POTERii. South of England (1858). Bred from Larv» in Poterium
sangu.sorba.
80. X. quinquella. Soutli of England (1848). On oak leaves, very
local. ? continental.
81. X. APICELLA. Local (1854). Probably confused with allied species
on the continent.
82. X. HE.A.DLEYELLA. Local (1854)). A rare .species.
83. *X. HODGKixsoNi. Lancashire.
84. *X. WOOLHOPIELLA. Herefordshire.
85. *X, SERELLA. Westmoreland and S. England.
86. *X. AUROMARGINELLA. Dorset (1890).
87. *mlcropteryx sangti. (18911
88. *m. salopiella.
Pterophorixa.
89. Agdistis BENNETTii. East coast. I. of Wight (1840). Common on
Statice hmonium.
We have here a list of eighty-nine species, which,
according to the best authorities, are, in the present state
of our knowledge, peculiar to Britain. It is a curious fact
that no less than fifty of these have been described more
than twenty-five years ; and as during all that time they
have not been recognised on the continent, notwith-
standing that good coloured 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 we must
not apply this argument too rigidly, for the very day before
my visit to Mr. Stainton he had received a letter from
Professor Zeller announcing the discovery on the continent
of a species of our last family, Pterophorina, which for
more than forty years had been considered to be exclu-
sively British. This insect, PlatyiJlilia simUidactyla
[PtcT02:)hoTus isoclactylus, Stainton's Manual), had been
taken rarely in the extreme north and south of our islands
— Teignmouth and Orkney, a fact which seemed some-
what 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
, HAP. XVI THE BRITISH ISLES Sf.l
equally rare and not yet tbuml on the continent. iJut
this is hardly in accordance with the laws of distribution.
Widely scattered species are generally abundant in soine
localities ; while, w^hen 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, combined with our varied soil and
vegetation, offer conditions which may favour the survival
of some species with us after they have become extinct on
the continent.
Of the sixty-nine species recorded in my first edition
fourteen have been since discovered on the continent, while
no less than twenty-two species and eleven varieties have
been added to the list. As we can hardly suppose con-
tinental entomologists to be less thorough collectors than
ourselves, it ought to be more and more difficult to find
any insects which are unknown on the continent if all ours
really exist there ; and the fact that the list of apparently
peculiar British species is an increasing one renders it
probable that many of them are not only apparently but
really so. Both general considerations dependent on the
known laws of distribution, and the peculiar habits, con-
spicuous appearance, and restricted range, of many of our
species, alike indicate that some considerable proportion of
them Avill remain permanently as peculiar British species.
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 the Sprcies and Varieties of Beetles iclnch, so far as at present knovni,
are confined to the British Islands. Those added since the first edition
are marked uifh an asterisk.
Carabidj:.
1. ^Bembidium saxatile, rar. vectexsis (Fowler). Islf of Wij^lit.
2. DiioMius VECTEXSIS (Rvc). Common in the Isle of Wijilit, also in
Kent, and at Weymouth an<l Seaton. Closely allied to D. s.yvia.
3. Harjiulus latus, rar. metallescexs (Rye). Uniciue, but very
marked ! Soutli coast. " Terhaps a sport or a hybritl " (Fowler).
4. Acui'ALPUs DEiiELKTUs (Dawson). T^nique ! North Kent. Canon
Fowler thinks it may Ix- a variety of A. dursalis.
352 ISLAND LIFE
Dyticid^.
5. *Acilius sulcatus, rar. scoTicus (Ciu'tis). Scotland. A melauie
variety.
Helophoeid^:.
6. OcHTHEBius rowERi (Rje). Yery marked. S. coast. A few speci-
mens only.
7. *0. ^NEUS (St9ph).
Beachyelytra.
8. OcYUSA hibernica (Rye). Ireland, mountain tops, and at Braemav.
9. *OxYPODA TARDA (Sharp).
10. ., PECTITA (Sharp). Scotland.
11. ,, YERECUNDA (Sharp). Scotland, also London districts.
12. HoMALOTA DiYERSA (Sharp).
13. ., FULYIPENNIS (Rye).
11, ,, OBLONGiiTSOULA ' (Sharp). Scotland, also England an.l
Ireland.
15. ., PRiNCEPS (Sharp). A coast insect.
16. ,, CURTIPENNIS (Sharp). Scotland and near Birmingham.
17. H. levana, var. setigera (Sharp).
18. Stenus oscillator (Rye). Unique! South coast. May be a
hybrid,
19. Trogophl^us spinicollis (Rye). :Mersey estuary, unique ! Most
distinguishable, nothing like it in Europe. Perhaps imported from
another continent.
20. EuDECTUS AVHiTEi (Sharp). Scotch hills. A variety of E. '^'.raucli
of Germany (the only European species) /f?c Kraatz (Sharp).
21. HoMALiuM RUGULIPENNE (Rye). Exceedingly marked form.
Northern and western coasts ; rare.
22. *MYCETOPORrs monticola (Fowler). Cheviots and Inverness-shire.
ScYDMiENID.E.
23. *ScYDM.ENUS po^VERI (Fowler) S. England. A recent discovery.
24. *S. PLANIFRONS (Fowlerl ,, .,
Pselaphid.t:.
25. Bryaxis cotus (De Sauley). Scotland.
26. Bythinus glabratus (Rye). Sussex coast ; also Isle of Wight ; a
few specimens ; very distinguishable ; myrmecophilous (lives in ants'
nestsl
Trichopterygid.i^.
27. Ptinella MARIA (Matthews) Derbyshire,
28. Trichopteryx sar.e ( ,, ) Notts.
29. ,. poweri ( .. ^ Oxon.
30. EDITHIA ( ,. ) Kent,
31. .. *ANGUSTA ( .. ) Leicestershire.
32. ., KiRBii ( .. ) Norfolk.
33. .. fratercula( .. )
34. ., W\A.TERH0USIl( ., )
35. ., CHAMPiONls( .. ) Wickeu Fen.
36*. ,, JANSONI ( ., "^ Leicestershire.
37. ,, SUFFOCATA (Haliday). Ireland, Co. Cork.
38, ,, CARBONARI A (]\Iatthews). Notts.
CHAP. XVI THE BRITISH ISLES 353
39. Ptilium halidayi (Matthews). Sherwood Forest.
40. ,, CALEDONICUM (Sharp). Scotland ; very marked form.
41. ,, INSIGNE (Matthews). London district.
42. *ORTHOPEiirs MUNDUs (Matthews). Oxfordshire.
43. *0. PUNCTULATUS (]\Litthews). Lincolnshire.
Anisotomidj;,
44. AaATHiDiUM rhinoceros (Sharp). Old fir-woods in Perthshire ;
local, many specimens ; a very marked species.
45. Anisotoma siMii.ATA (Rye). South of England. T^s'o specimens.
46. ,, LUNicoLLis (Rye). North-east and South of England, a
very marked form ; several specimens.
Phalacrid^e.
47. Phalacrus BRisouTi (Rye). South of England. Rare. "Perhaps
a small form of P. coriisciis" (Fowler).
Cryptophagidji;.
48. Atomaria divisa (Rye). Unique ! South of England.
Lathridiida'.
49. Melanopthalma transversalis, var. WOLLASTONI (Waterhousc). South
coast, and Lincolnshire.
Byrrmid^.
50. SyNcalypta hirsuta (Sharp). South of England, local. "Closely
allied to ^S*. sdigcra'^ (Fowler).
MORDELLIDJ:;.
5L *Anaspis SEPTENTRIONALLS. Scotland (1891 ). (Champion.)
52. * „ GARNEYSi (Fowler), London District. (1890.)
Telephorid.e.
53. Telephorus darwinianus (Sharp). Scotland, sea-coast, A stunted
form of abnormal habits. Perhaps a variety of T. lUuratus.
Cypiionida'.
54. Cypiion PUNCTiPENNis (Sharp). Scotland.
Anthicid^k.
55. Antiiicus salinus (Crotch). South coast.
^^. ,, scoTicus (Rye). Loch Levcn ; very distinct ; many speci-
mens.
ClOlD^.
57. *Cis BiLAMELLATUs (Wood). "West Wickhaiu, Kent. '' Perhaps im-
ported. Has the appearance of an exotic Cis " (Fowler).
TOMICID^.
58. *Pityopthorus lichtcnsteiuii, var. scoTicus (Blandford). Scotland.
CURCULIONID.*:.
59. Ceuthorhynchus contractus, var. pallipe.s (Crotch). Lundy Island ;
several specimens. A curious variety only known from this island.
60. Lio.soMUS TR0GL0UYTE.S (Ryc). A very queer form. Two or three
specimens. South of England.
61. *Orchcitcs ilici.s, rff7-. XIGRIPES (Fowler). London Dititrict. ^1890.)
A A
354 ISLA^'i) LIFE part it
62. Apion eyei (Blackburn). Shetland Islands. Several specimens.
Perhaps a var. of A. fagi.
Chrysomelid^.
63. Chrysomela staphylea, var. sharpi (Fowler). Solway district.
HALTICID.E.
64. LoNGiTARsrs AGiLis (Rye). South of England ; many specimens.
65. ,, DisTiNGUENDA (Rye). South of England ; many speci-
mens.
QQ. PsYLLioDES LURiDiPENNis (Kutschcra). Lundy Island. A very
curious form, not imcommon in this small island, to which it
appears to be confined. "An extreme and local variety of
P. chnjsoccphala " (Fowler).
COCCINELLID^.
67. ScYMKUS LiviDUS (Bold). Korthumberland. A doubtful species.
Of the sixty-seven species and varieties of beetles in the
preceding hst,"^ a considerable number no doubt owe their pre-
sence there to the fact that they have not yet been discovered
or recognised 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 Avith the excessively minute Trichopterygidse
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 recognised by any
competent entomologist, and often so plentiful that they
can be easily obtained when searched for. The peculiar
species of Apion in the Shetland Islands is interesting, and
may be connected with the very peculiar climatal con-
ditions there prevailing, which have led in some cases to a
change of habits, so that a species of weevil {OtioThynchus
maurus) always found on mountain sides in Scotland here
occurs on tlie sea-shore. Still more curious is the occur-
rence 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 presence
here of peculiar insects can only be due to isolation with
special conditions, and immunity from enemies or com-
peting forms. When we consider the similar islands off
CHAP. XVI THE BRITISH ISLES 355
tlie coast of Scotland and Ireland, with the Isle of ^lan and
the Scilly Islands, none of which have been yet thorougldy
explored for beetles, it is probable that many similar ex-
amples of peculiar isolated forms remain to be discovered.
Looking, then, at what seem to me the probabilities of
the case from the standpoint of evolution and natural
selection, and giving due weight to the facts of local
distribution as they are actually presented to us, I am
forced to differ from the opinion held by our best entomo-
logical authorities, and to believe that some at least,
perhaps many, 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 follow-
ing information on certain Trichopterous Neuroptera (or
caddis-flies) which appear to be confined to our islands.
The peculiar aquatic liabits of the larvai of these insects,
some living in ponds or rivers, others in lakes, and others
again only in dear mountain streams, render it not improb-
able that some of them should have become isolated and
preserved in our islands, or that they should be modified
owing to such isolation.
Tricho2)tera 'peculiar to the iJritish Isles.
1, Philopotamus ixsuLARis. (? 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. montanus, a species found both in Britain and on the continent,
but it dilfersin its strikingly yellow colour, and less prouounced markings.
All the specimens from Guernsey are alike, and resident entomologists
assured Mr. McLachlan that ]io other kind is known. Strange to say,
some examples from Jersey ditfer considerably, rcscmlding the common
European and British form. Even should this ])e('uliar variety be at some
future time found on the continent it would still be a ronarkablc fact that
tlie form of insect inhabiting two small islands only twenty miles a]>art
should constantly ditfer ; but as Jersey is between Guernsey and the coast,
it seems just possiljle that the more insular conditions, and perhaps some
l)eculiarity of the soil and water in the former islanil, have really led to
tlie production or preservation of a well-marked variety of insect. In the
first edition of this work two other species were named as then, peculiar
to Britain — Sctodcs argentijtunctclla and Rhyacophila nuimla, Init both
liave now l)een taken on the continent.
2. Mi:s(ii'iiYLAX iMrrN( TATrs, rar. zi:n,.\Nnicus. — A variety of a
Soutli and Central European species, one specimen of which has lieen
found in Dumfriesshire. The variety is distinguished by its small size and
dark colour.
A A 2
S56 ISLAND LIFE pat^t it.
Land and Freshwater Shells. — In the first edition of this
work four species were noted as being, so far as was then
known, exchisively British. Two of these, Cyclas pisi-
dioides (now called Sphwrium ])isidioides) and Gcomalacus
macidosus, have been discovered on the continent, but the
other two remain still apparently confined to these islands ;
and to these another has been added by the discovery of a
new species of Hydrobia in the estuary of the Thames.
The peculiar species now stands as follows : —
1. LiMNEA INVOLUTA. — A pond snail with a small polished amber-
coloured shell found only in a small alpine lake and its inflowing stream
on Cromagloun mountain near the lakes of Killarney, It was discovered
in 1838, and has frequently been obtained since in the same locality. It
is sometimes classed as a variety of Limnca percgra, and is at all events
closely allied to that species.
2. Hydrobia jenkinsii. — A small shell of the family Rissoidfe inhabit-
ing the Thames estuary both in Essex and Kent. It was discovered only
a few years ago, and was first described in 1889.
3. AssiMiNEA GRAYANA. — A Small estuarinc pulmonobrancli found ou
the banks of the Thames between Greenwich and Gravesend, on mud at
the roots of aquatic plants. It has been discovered more than sixty years.
But besides the above-named species there are a con-
siderable number of well-marked varieties of shells which
seem to be peculiar to our islands. A list of these has
been kindly furnished me by Mr. Theo. D. A. Cockerell,
who has paid much attention to the subject ; and after
omitting all those whose peculiarities are very slight or
whose absence from the continent is doubtful, there remain
a series of forms some of which are in all probability really
endemic with us. This is the more probable from tlie fact
that an introduced colony of Helix nemoralis at Lexington,
Virginia, presents numerous varieties among which are
several which do not occur in Europe.^ The following list
is therefore given in the hope that it may be useful in
calling attention to those varieties which are not yet posi-
tively known to occur elsewhere than in our islands, and
^ See "The Virginia Colony of Helix nemoralis," T. D. A. Cockerell.
in The Nautilus, Vol. III. No. 7, p. 73.
CHAP. XVI THE BRITISH ISLES 357
thus lead, ultimately, to a more accurate knowledge of the
facts. It is only by obtaining a full knowledge of varieties,
their distribution and their comparative stability, that we
can ever hope to detect the exact j^rocess by wliich nature
works in the formation of species.
List of the Species and Yakieties of Land and Fiieshwater
Shells which, so far as at present known, are believed to be
Peculiar to the British Isles or not found on the Continent.
LlMACID^.
1. Limax marginatus, r«>'. maculatus. Ireland ; frequent, very distinct.
2. ,, ,, ,, decipiens. Ireland and England.
3. ,, flavus, var. suffusus. England ; JMelanic form.
4. ,, ,, ,, GRISEUS. England ; Melanic form.
5. Agriolimax agrestis, var. nicer. Yorkshire, IMelanie. Azores.
6. ,, ,, ,, GRISEUS. England. Melanic.
7. Amalia gagates, var. rava. W. of England.
8. ,, sowerbyi, var. rustica. England.
9. ,, ,, ,, NiGRESCENs. SiUTcy and Middlesex.
10. ,, ,, ,, BicoLOR. Ealing.
11. Hyalina crystallina, var. complanata. Near Bristol.
12. ,, fulva, var. alderi.
13. Yitrina pellucida, var. depressiuscula. S. England, "Wales.
Helicid^e.
14. Arion ater, var. albo-lateralis. England, \Yales, Isle of jMan ;
very distinct.
15. ,, hortensis, var. fallax. England. Common at Boxliill,
16. Geomalacus maculosus. Kerry and Cork. Three varieties have
been described, one of which occurs in Portugal.
17. Helix aspersa, var. lutescens. England. Not rare perhaps in
France.
18. ,, nemoralis, var. hibep.nica. Ireland.
19. ,, rufescens, var. manchesteriensis. England.
20. ,, hispida, var. subglobosa. England.
21. ,, ,, ,, depilata. England.
22. ,, ,, ,, MINOR. England, Ireland.
23. ,, granulata, var. cornea. Lulworth, Dorset.
24. ,, virgata, var. subaperta. Bath.
25. ,, ,, ,, SUBGLOBOSA. England, Wales, Bantry Bay.
26. ,, ,, ,, CARINATA. Wareham, Dorset.
27. ,, caperata, var. major. England, Wales, Scotland. Distinct.
28. ,, ,, ,, NANA. England.
29. ,, ,, ,, SUBSCALAPJS. Wales, Ireland.
30. ,, ,, ,, ALTERNATA. England, Kent.
31. ,, acuta, var. nigrescens. England.
PuPIDiE.
32. Pupa anghea, var. pallida. Not rare.
33. ,, lilljeborgi, var. bidentata. Ireland.
358 ISLAND LIFE part ii
34. Pupa pygmea, var. PALLIDA. Dorset and Devon.
35. Clausilia rugosa, var. parvula. Ireland.
SXEXOGYKIDiE.
36. Coclilicopa lubrica, rar. hyalina. Wales, Scotland.
37. Ccjecilianella acieula, var. anglica. England.
SUCCINEID^.
38. Snccinea putris, var. solidula. Wiltshire.
39. ,, virescens, var. ArREA, Ireland.
40. ., pfeifferi, ,, rufescens. England, Ireland.
41. ,, ,, ,, MINOR. England.
LlMN^EID^.
42. Planorbis fontanus, var. minor. England.
43. ,, carinatus, ,, disciformis. England.
44. '., contortus, ,, excavatus. Ireland.
45. j. ,, ,, minor.
46. Pliysa fontinalus, var. oblonga. England, Wales, Ireland.
47. LiMNiEA INVOLUTA. Ireland.
48. Linmrea glutinosa, var. mucronata.
49. ,, peregra, var. burnetti. Scotland. Very distinct.
50. ,, ,, ,, LACUSTRis. Perhaps in C. Yerde Islands.
51. ,, ,, ,, MARITIMA. Great Britain.
52. ,, ,, ,, lineata. England.
53. ,, ,, ,, STAGNALiFORMis. England.
54*. ,, stagnalis, var. elagantula. Curious. In a pond at
Chislehurst.
55. ,, palustris, var. CONICA. England, Ireland.
56. ,, ,, ,, TiNCTA. England, Wales.
57. ,, ,, ,, albida, England.
58. ,, truncatula, var. elegans. England, Ireland. Distinct.
59. ,, ,, r, FUSCA. Wales.
60. Ancylus lacustris, var. compressus. England.
Paludinid^s:.
61. Paludina vivipara, var. efasciata. England. Xot uncommon,
62. ,, ,, ,, atropurpurea. Pontypool.
RlSSOID^.
63. Hydrobia jenkinsii. Thames Estuary.
64. ,, ventrosa, var. minor.
65. ,, ,, ,, decollata.
66. ,, „ ,, OYATA.
67. ,, ,, M ELONGATA.
68. ,, ,, „ PELLUCIDA.
Cyrenid.^.
69. Sphaerium corneum, var. compressum.
70. „ „ „ minor.
71. ,, ,, ,, stagnicola.
72. ,, ovale, var. pallidum. England.
73. ,, lacustre, var. rotundum. Wales.
74. Pisidium pusilluni, var. grandis.
75. ,, ,, ,, circulare. Wales.
76. ,, nitidum, var. glubosum.
( HAi'. XVI THE BRITISH ISLES 359
Unionidj;.
77. Uuio tumidus, var. niciiEXSis. Regent's Park. Poculiar form,
78. ,, pictorum, rar. latior. England,
79. ,, ,, ,, COMPRESSUs, England.
8(X ,, margaritifcr, var. olivaceus,
81, Anodonta oygnpea, var. incrassata. England,
82, ,, ' ,, ,, PALLIDA. England, Ireland.
ESTUARINE OR MaRIXE PuLMOXOTRAXCIIS.
83, AssiMiXEA grayana. Thames Estuary.
PecuJiarities of the British Flora.- — Thinking it probable
that there must also be some peculiar Britisli plants, but
not finding any enumeration of such in the JJritish Floras
of Babington, Hooker, or Bentham, I applied to the
greatest livhig authority on the distribution of British
plants — the late Mr. H. C. Watson, who very kindly gave
me the information I required, and I cannot do better
than quote his words : " It may be stated pretty con-
fidently that there is no ' species ' (generally accepted
among botanists as a good species) peculiar to the British
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 Ruhi Professor Babington includes as good species,
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 Avell acquainted 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.' "
In my first edition I was only able to name four species,
sub-species, or varieties of flowering plants which were
believed to be unknown on the continent. But much
attention has of late years been paid to the critical ex-
amination of British plants in comparison wdth continental
specimens, and I am now enabled to give a much more
360 ISLAKD LIFE
extensive list of the species or forms which at present seem
to be peculiar. For the following list I am primarily in-
debted to Mr. Arthur Bennett of Croydon. Sir Joseph
Hooker has been so kind as to examine it carefully and to
give me his conclusions on the relative value of the differ-
ences of the several forms, and Mr. Baker, of Kew, has also
assisted with his extensive knowledge of British plants.
List of Species, Sub-species, and Yapjeties of Flo-sverixg Plants
FOUND IN Great Britain or Ireland, but not at present known
in Continental Europe. By Arthur Bennett, F.L.S. The
most distinct and best determined forms are marked with an
asterisk.
1. ""Caltlia radicans (Forst.). "A nuicli disputed species, or form of C.
■palustri-s. It is a relativelj'- rare plant," (J. D. H.) "Certainly
distinct from the Scandinavian form." (Ar. Bennett.)
2. *Arabis petrtea (Lam.) m/-. grandifolia (Druce). Scotch mountains.
"The larger flowers alone distinguish this." (J. D. H.)
3. Arabis ciliata (R. Br.). In Xyman's Conspectus Florcc Europccce
this species is given as found in England and Ireland only.
" A very much disputed form of a plant of very wide distilbution
in Europe and Xorth America." (J. D. H.)
4. Brassica monensis (Huds. ). " This and the continental B. cheirantJms
(also found in Cornwall) are barelv distinguishable from one
another." (J. D. H.)
5. Diplotaxis muralis (D. C. ) var. Babingtonii (Syme). South of England.
"A biennial or perennial form; considered to be a denizen l>y
AVatson." (J. D. H.)
6. *Helianthemum guttatum (^lill), var. Breweri (Planch). Anglesea.
" Very doubtful local plant. H. guttatum (true) has lately been
found in the same locality." (J. D. H. )
7. '"Polygala vulgaris (L.), var. grandiflora (Bab). Sligo, Ireland. "A
very distinct variety. " (J. D. H.)
8. Viola lutea (Huds.), var. amcena (Symons^. " F. lutca itself is con-
sidered to be a form of V. tricolor, and V. amcena the better coloured
of the two forms of V. lutca.'" (J. D. H.)
0. *Cerastium arcticum (Lange), var. Edmonstonii (Beeby). Shetland Is.
"But C. arcticum is referable to the very variable C. alpinum." (J.
D. H.) " Near to the European C. latifoUnm." _ (Ar. Bennett.)
10. *Geranium sanguineum (L.), var. Lancastriense (AYith.). Lancashire.
"A prostrate local form growing out of its native soil in sand by the
sea." (J. D, H.) Mr. Bennett writes : " I have grown G. sangtirneum^
and its prostrate variety in sand, and neither became Lanca^triense. "
11. Genista tinctoria (L.), var. humifusa (Dickson). Cornwall. "A
decumbent hairy form confined to the Lizard." (J. D. H.)
12. Cytisus scoparius ' (Link. ), mr. prostratus (Bailey). Cornwall. "A
prostrate form." (J. D. H.)
13. Anthyllis vulneraria (L.), var. ovata(Bab.). Shetland Is. "A slight
vafietv." (J.D.H.)
14. *Trifolium repens (L.), var. Townsendii (Bab.). Scilly Isles. "A well-
( IIAI'. \\ I
HI': liKITISII ISLKS 361
marked form by its rose-purple flowers. Confined to the Scilly
Isles." (J. D. H.)
15. *Rosa involnta (Sm.), car. Wilsoni. (Borrer.) Wales. "There are a
multitude of forms or varieties of /t. involuta, andiJ. wilsoniis one of
the best-marked, found on the Menai Straits and Derry." (J. D. H.)
16. Rosa involuta var. gracilis (Woods). "This is considered by many as
one of the commonest forms of R. invohifn." (J. D. H.)
17. Rosa involuta var. Nicholsoni (Crepin). " Another slight variety of
E. involute f." (J. D. H.)
IS. Rosa involuta var. Woodsiana (Groves). "A Wimbledon Common
varietv of R villosa. " (J. D. H. )
19. Rosa involuta var. Grovesii (Baker). ":Mr. Baker thinks this of no
account." (J. D. H.)
20 Rubus echinatus (Lind. ). "A variety of the widely spread 72. RcuMa,
itself a form of R. fruticosn^." (J. D. 11.)
21. *Rubus longithyrsiger (Lees). "Mr. Baker informs me that this is a
very distinct plant never yet fo\md on tlie continent. " (J. I). H.)
22. Tyrus aria (Sm.) var. rupicola (Syme). "A very local form, confined
'to Gt. Britain, and owing its characters to its starved position."
(Baker.)
23. Callitriche obtusangula (Le Gall), w,r. Lachii (Warren). Cheshire.
* * This is intermediate between two sub-species of C. verna. " ( J. D. H. )
24. *iEnanthe fluviatilis (Coleman). South of England. "The fluitant
formofyiJ. Phcllandrium." (J. D. H.)
25. Anthemis arvensis (L. ), va;r. anglica (Spreng). K Coast of England.
"A maritime form with more fleshy leaves formerly found near
Durham. It has other very trifling characters." (J. D. H.)
26. Arctium intermedium (Bab. ). * ' There are two sub-species of A. lap'pa,
majiis and minus, each with varieties, and this is one of the inter-
mediates." (J. D. H.)
27. Hieracium holosericium (Backh.). Scotch Alps.
28. H. gracilentum (Backh.). ,,
29. II. lingulatum (Backh.). ,, A var. of this in Scand-
inavia.
30. H. senescens (Backh.). ,,
31 H. chrysanthenum (Backh.). ,,
32. H. i'icum (Fr.). Teesdale and Scotland.
33. H. gibsoni (Backh.). Yorkshire and Westmoreland.
34. Hiei-aciuin nitidum (Backh. ). Lower glens of the Scotch Alps. :Mr.
Bennett writes : — "The following Hieracia have been named by
]\Ir. F. J. Hanl)ury as endemic forms. One can only safely say they
are certainly not known in Scandinavia, as they have all been .sul)-
mitted to Dr. Lindeberg. But usually Scotch species are not
represented in Central Europe to any great extent, though several
do occur. Still these new forms ought to be critically compared
with all Dr. Peters' new species."
35. H. Langewellense (Hanb.). Caithness.
36. H. pollinarium (Hanb.). Sutherland.
37. II. scoticum (Hanb.). Sutherland and Caitlmess.
38. H. Backhousei (Hanb.). Aberdeen, Banfl; Inverness.
39. H. caledonicum (Hanb.). Caithness and Sutlierland.
40. H. Farrense (Hanb.). Sutherland and Shetland Is.
41. H. proximum (Hanb.). Caithness. With regard to all these
3^2 ISLAND LIFE part ii
Hieracia Sir Joseph Hooker and Mr. Baker say :— "Xo case can
he made of these. They are local forms Avith the shadowest of shady
characters." Mr. Bennett writes : " H. iriciim and H. Gibsoni are
the best marked forms."
42. *Campanula rotundifolia (L.), var. speciosa (A. G. More). W. Ireland.
" Very well distinguished by its large flowers and small calyx lobes,
approaching the Swiss C. Scheuzeri." (J. D. H.)
43. Statice reticulata (Sm.). "Baker agrees with me that this is also a
Mediterranean species." (J. D. H.)
44. Erythrsea capitata (AVilld.), rar. sphferocephala (Towns.). Isle of
Wight. ' ' A form of E. cnitoAirium utterly anomalous in its genus
in the insertion of the stamens. A monster rather than a species."
(J. D. H.)
45 *Erythrffia latifolia (Sm. ). On the sandy dunes near Liverpool. "A
local form." (J. D. H.)
46. Jklyosotiscollina (Hoffim.), var. Mittenii (Baker). Sussex.
47. Veronica officinalis (L.), var. hirsuta (Hopk.). Ayr, Scotland.
48. Veronica arvensis (L.), var. eximia (Towns.). Hampshire.
49. Mentha alopecuroides (Hull). Nearest to M. dulcissinia (Dum,).
50. Mentha pratensis (Sole). Only once found.
51. Chenopodium rubrum (L.), va.r. pseudobotryoides (H. C. Watson).
52. Salix ferruginea (Forbes), England, Scotland. "Probably a hybrid
between"*?, viminalis and S. cimreaj' (J. D. H.)
53. Salix Grahami (Borr. ). Sutherland, Perth. ' ' A hybrid ? " (J. D. H. )
54. Salix Sadleri (Syme). Aberdeen. "Ahybiid?" (J. D. H.)
55. *Spiranthes Romanzoviana (Cham.). Ireland (N, America).
56. *Sisyrinchium angustifolium (Mill.). Ireland. (Arctic and Temp. N.
America.)
57. Allium Babingtonii (Borrer). "West England, West Ireland. ' ' A
form o{ A.^iinpcloprasum, itself a naturalised species." (J. D. H.)
58. *PoTAMOGETON LANCEOLATUS (Sm.). Anglesea, Cambridgeshire, Ire-
land. Mr. Bennett writes : — " Endemic ! I have taken a good amount
of trouble to ascertain this. Nearly 400 specimens I have distributed
all over the world with requests for information as to anything like
it. The response is everywhere the same, ' nothing.' The nearest to
it occurs in the Duchy of Lauenberg but is referable to P. hetero-
59. Potamogeton Griffithii (Ar. Bennett). Carnarvon. "Nearest to this
is a probable hybrid from N. America, but not identical." (Ar.
Bennett.)
60. Potamogeton pusillus (L.), sub-sp. Sturrockii (Ar. Benn.). Perth.
61. Potamogeton pusillus (L.)/ var. rigidus (Ar. Benn.). Orkneys,
Shetlands.
62. Ruppia rostellata (Koch.), var. nana (Bosw.). Orkneys.
63. *Eriocaulon septangulare (AVith. ). Hebrides, Ireland. N. America.
64. Scirpus uniglumis (Link), wr. Watsoni (Bab.). Scotland, England.
"This is a variety of a sub-species of the common S. pahistris."
(J. D. H.)
65. Luzula pilosa ( Willd. ), var. Borreri ( Bromf).
66. *Carex involuta (Bab.). Cheshire. " A distinct enough plant but
probably a hybrid between C. vesicaria and C. am2niUacca, found in
one place only." (J. D. H.)
67. Carex glauca (MuiT.), var. stictocarpa (Sm.). Scotland.
CHAr. XVI THE BRITISH ISLES 363
6S. Carex precox (.Tacq.). '^■'''■- ''apitata (Ar. Benn.). Ireland. "A
remarkable plant (monstrosity?) simulating C. ccqntata (L.)." (Ar.
Bennett.)
69. *Carex Grahanii (Boott). " A mountain form of C. vcskaria." (J.
D. H.)
70. *Spartina Townsendi (Groves). Hampshire. " A distinct but veiy
local form of *S'. strlcta, found in one place only." (J. D. H.)
71. Agrostis ni;[;ra (With.).
72. Deschampsia flexuosa (Trin.), var. Yoirlichensis ( J. C. IVk'lvill), Perth.
73. *D('yeuxia neglecta (Kunth), var. Hookeri (Syme). Ireland. "A
distinct variety confined to Lough Neagh." (J. D. H. )
74. Glyccria maritima (Willd.), var. riparia (Towns.). Hampshire.
75. Poa Balfouri'(Bab.). Scotland. " An alpine .sub-variety of a variety
of the protean P. ncraoralis.''' (J. D. H. )
In liis 'coinmcnts on this extensive list of sn2:)}:)0sed
peculiar British plants, Sir Joseph Hooker arrives at tlie
followino- conclusions : —
o
1. There are four unquestionably distinct .species which do not occur in
continental Europe : viz. —
One ahsolutelv endemic species, Potamogeton LANCEOLAxrs.
Three American species, Slsyhinchium axgustifolivm, Spikanthes
EOMANZOVIAXA, ErIOCAULON SETTANGULARE.
2. There are sixteen endemic varieties of Briti.sh species, viz. —
Eleven of more or less variable species, Caltha palustris, var. radicaxs ;
Polygala vulguris, var. grandiflora ; Cerastium arcticum, var. edmon.s-
TONii ; Trifolium repens, var. Towxsendii ; Rosa involuta, var. wii.soxi ;
Rubus fruticosus, suh-sj). loxgitiiyrsiger ; Campanula rotundifolia, car.
sPECio.SA ; Erythrrea centaurium, mh-sp. latifolia ; Carex involuta,
(?Hyb.); Carex vesicaria, var. Graiiami ; Deyeuxia neglecta, var.
Hookeri.
Five of comparatively well limited species. Arabis petrrea, var. oraxdi-
FOLIA ; Heliantheinum guttatum, var. Breweri ; Geranium sanguineum,
var. Laxcastriexse ; ^nantho Phellandrium, var. fluviatilis ;
Spartium stricta, var. Towxsexdi.
The above twenty species are marked in the list ^Yith
an asterisk. Of the remaining fifty-five, Sir Joseph
Hooker says, " that for various reasons it would not be
safe to rely on them as evidence. In most cases the
varietal form is so very trifling a departure from the type
that this may be safely set down to a local cause, and is
probably not constant. In others the plant is doubtfully
endemic ; in still others a hybrid."
Even should it ultimately prove that of the whole
number of the fifty-fivo doubtful forms none are established
a§ peculiar British varieties, the number admitted after so
364 ISLAND LIFE pakt ii
rigorous an examination is about what we should expect in
comparison with the Hmited amount of speciality we have
seen to exist in other groups. The three American species
which inhabit the extreme west and north-west of the
British Isles, but are not found on the continent of Europe
are especially interesting, because they demonstrate the
existence of some peculiar conditions such as would help
to explain the presence of the other peculiar species.
Whether we suppose these American forms to have
migrated from America to Europe before the glacial epoch,
or to be the remnants of a vegetation once spread over the
north temj^erate zone, we can only explain their presence
with us and not further east by something favourable
either in our insular climate or in the limited competition
due to our comparative poverty in species.
About half of the peculiar forms are found in the
extreme west or north of Britain or in Ireland, where
peculiar insular conditions are at a maximum ; and the
influence of these conditions is further shown by the
number of species of West or South EurojDean plants which
occur in the same districts.
We may here notice the interesting fact that Ireland
possesses no less than twenty species or sub-si^ecies of
flowering plants not found in Britain, and some of these
hiay be altogether peculiar. As a whole they show the
effect of the jDre-eminently mild and insular climate of
Ireland in extending the range of some south European
species. The following list of these plants, for which I am
indebted to Mr. A. G. More, with a few remarks on their
distribution, will be found interesting : —
List of IrjsH Flowehixg Plants which aee xot found in Britain.
1. Polygala vulgaris (var. graiidiflora). Sligo.
2. Camiximda rotundifolia {var. speeiosa). AV, Ireland.
3. Arenaria ciliata. W. Ireland (also Auvergne, Pyrenees, Crete).
4. Saxifraga umhrosa. "W. Ireland (also Pyrenees, N. Spain, Portugal).
5. ,, geum. S. AV. Ireland (also Pyrenees).
6. ,, hirsiUa. S. AV. Ireland (also' Pyrenees).
7. Inula salicina. "W. Ireland (Scandinavia, ]\Iiddle and South Europe).
8. Urka mcditcrraiua. "W. Ireland (W. France, Spain, Portugal),
9. ,, iiiackaiana {fetralix sxxh.-s,^.)^^. Ireland (Spain).
1 0. Arbutus uncdo. S, W. Ireland ( W. of France, Spain, Portugal and
shores of Mediterranean).
11. DaUocia iMlifolia. W. Ireland ("NY. of France, Spain and Portugal).
citAP. XVI THE BRITISH ISLES 365
12. Pingicicula gramUjiora. S. W. Ireland (Spain, Pyrenees, Alps of
France and Switzerland).
13. Ncotinca intada. "\V. Ireland (S. France, Portugal, Spain, and
shores of Mediterranean).
14. Sjnmnthcs romanzoviana. S. W. Ireland (Nortli America).
15. Sisyrinchium angustifolium. W. Ireland (North America, Arctic and
Temp. ).
16. Potamogdon hmchitcs. Ireland, Mr. Arthur Bennett informs mc that
this is certainly not British or European, but may possibly be
identical with P. flmtans var. Amcricanns of the U. States.
17. Potamogdon kirkii{natansB\\\).-s^.). W. Ireland. (Arctic Europe ?)
18. Eriocaulon septangularc. AV. Ireland, Skye, Hebrides (Xorth
America).
19. Carcx huxhaumii. N. E. Ireland, on an island in Lough Xeagh (Arctic
and Alpine Europe, North America).
20. Dci/ciuia ncgleda {var. Hookcri). On the shores and islands of Lough
Neagh, (And in Germany, Arctic Europe, and North America. )
We find here nine soutli-Avest European species which
probably had a wider range in mild preglacial times, and
have been preserved 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 con-
tinental, so that these plants may have followed the
retreating ice to their present stations and survived
the subsequent depression. Tliis seems more probable
than that so many species should have reached Ireland for
the first time during the last union witli the continent sub-
sequent 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
favourable conditions, have continued to exist in Ireland
while becoming extinct in the adjacent parts of Britain
and Western Europe.
As contracted Avith the extreme scarcity of peculiar
species among the flowering plants, it is the more interesting
and unexpected to find a considerable number of peculiar
mosses and Hepaticie, some of which present us with phe-
nomena of distribution of a very remarkable character.
For the following lists and the infn-mation as to the dis-
tribution of the genera and species I am indebted to Mr.
William Mitten, one of the first authorities on these beau-
tiful little plants. That of the mosses has been corrected
for this edition by Dr. K. Braithwaite, and several species
of hepaticoe have been added by Mr. Mitten.
ISLAND LIFE
List of the Species of Mosses and Hepatic^ which are peculiar to
THE British Isles (or not found in Europe).
( Those belongmg to non-European genera in Italics. )
Mosses,
1 . Systegiiim Mittenii South England.
2. Campylopus Shawi i Xorth Britain.
3. , , setifolius Ireland, Wales, and Hebrides.
4. Seligeria calcicola South England.
5. Pottia viridifolia South England.
6. Leptodontium recurvifolium . . . Ireland and Scotland.
7. Tortula Hybernica Ireland.
8. StrcjJtopogon gcmmascens Sussex.
9. Bryum barbatum Scotland.
10. Bartramidula WiJsoni Ireland, AVales, and Scotland.
11. Daltonia splachnoides Ireland, Antilles, and Mexico.
12. IlooJceria laetcvircns Ireland, Cornwall, and ^Madeira.
13. Hypnum niicans Ireland.
14. Myuriulu Hebridarium Hebrides and Atlantic Islands.
15. Hedwigia ciliata rar. striata ... Wales and Scotland.
Hepatic-e.
1 . Frullania germana Ireland.
2. ,, Hutchinsife Ireland, Scotland, "Wales, Devon,
Tropical regions.
3. Lejeunia flava Ireland, Atlanticlslands, S.America,
Africa, &c.
4. , , niicroscopica Ireland, Wales, Cumberland, JMadeira.
5. ,, Holtii Ireland (Killarney).
6. , , diversiloba Ireland ( Killarney), ]\Iexico ?
7. ,, patens Ireland.
8. Radula tenax Ireland.
9. ,, Holtii Ireland.
10. ., voluta Ireland, Wales, Cumberland, Mexico?
11. ,, Carringtonii Ireland.
1 2. Lepidozia Pearsoni Wales.
13. Adilocolia decipiens Ireland, Wales, Africa, and S. America.
14. Cephalozia aeraria AVales.
15. Lophocolia spicata Ireland, Cornwall, Anglesea,
1 6. j^Iartinellia nimbosa Ireland ( Brandon jNIountain ).
1 7. Plagiochila spinulosa Wales, Ireland, and Scotland, Atlan
tic Islands.
18. 5 , ambagiosa Ireland, India.
1 9. Jamesoniella Carringtonii Scotland.
20. Gymnocolea Nevicensis Scotland.
21 . Jungemiannia Doniana Scotland.
22. Cesia crenulata Ireland, Wales.
23. Chasmatocolea cuneifolia Ireland,
24. Aerobolbus Wilsoni Ireland, S. America, ^STew Zealand.
25. Pctaloiihyllum Ralfsii Ireland, Cornwall, Devon.
CHAr. xvr THE BRITISH ISLES 36/
Many of the above are minute or obscure plants, and
are closely allied to other European species with which
they may have been confounded. We cannot tlierefore
lay any stress on these individually as being absent from
the continent of Europe so much of which is imperfectly
explored, though it is probable that several of them are
really confined to Britain. But there area few — indicated
by italics — which are in a very different category ; for
they belong to genera which are altogether unknown in
any other part of Euroj^e, and their nearest allies are to be
found in the tropics or in the southern hemisphere. The
four non-European genera of mosses to which we refer
all have their maximum of development in the Andes,
while the three non-European Hepaticse appear to have
their maximum in the temperate regions of the southern
hemisphere. Mr. Mitten has kindly furnished me with
the following i3articulars of the distribution of these
genera : —
Baetramidula. Asia, Africa, S. America and Australia, but not
Europe or N". America.
Stueptopogox is a comparatively small genus, ^Yitll seven species in the
Andes, one in the Himalayas, and three in the south temperate zone,
besides our English species.
Daltoxia is a 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.
HooKEiiiA (restricting that term to the species referable to Cyclodictyon)
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 Islands, one in New Zealand, one in Java, one
in India, 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 distribu-
tion, since Mr. Mitten assures me that the plants are so
markedly different from all other mosses that they would
scarcely be overlooked in Europe.
The distribution of the non-Euroj^ean genera of
Hepaticse is as follows : —
CHA8MAT0C0LIA. South America and Ireland.
AcKOBOLBrs. A small genus found only in Kcw Zealand and the
adjacent islands, besides Ireland.
ISLAXD LIFE
PETALorHYLLrM. A small genus confined to i\.iistralia and Isev,' Zealand
in the southern hemisphere, Algeria, and Ireland in the northern. We
have also one of the Hepaticai — Masiigojjhora JFoodsii—ioimd in Ireland
and the Himalayas, but unknown in any part of continental Europe.
The genus is most developed in New Zealand.
These are certainly very interesting facts, but they are
by no means so exceptional in this gronp of plants as to
throw any doubt ujDon their accuracy. The Atlantic islands
present very similar phenomena in the Ehamphidium
jmijniratum, 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, Avhich are found nowhere
else ; although the genus extends over Europe, India, and
the southern hemisphere, bat always represented by a
very few wide-ranging species except in this one mountain
group ! ^
Such facts show us the wonderful delicacy of the balance
of conditions which determine the existence of particular
species in any locality. The spores of mosses and
Hepaticse are so minute that they must be continually
carried through the air to great distances, and we can
hardly doubt that, so far as its powers of diffusion are
concerned, any species which fruits freely might soon
spread itself over the whole world. That they do
not do so must depend on peculiarities of habit and con-
stitution, which fit the different species for restricted
stations and special climatic conditions; and according as
the adaptation is more general, or the degree of special-
isation extreme, species will have wide or restricted ranges.
Although their fossil remains have been rarely detected,
we can hardly doubt that mosses have as high an antiquity
as ferns or Lycopods ; and coupling this antiquity with
their gi'eat powers of dispersal we may understand how
many of the genera have come to occupy a number of
detached areas scattered over the whole earth, but
^ I am indebted to Mr. Mitten for this curious fact.
I
CHAi". XVI THE BRITISH ISLES 369
always such as afford the pecuHar conditions of climate
and soil best suited to them. Tlie repeated clianges of
temperature and other cHmatic conditions, which, as we
have seen, occurred through all the later geological epochs,
combined with those slower changes caused by geograph-
ical mutations, must have greatly affected the distribution
of such ubiquitous yet delicately organised plants as
mosses. Throughout countless ages they must have been
in a constant state of comparatively rapid migration,
driven to and fro by every physical and organic change,
often subject to modification of structure or habit, but
always seizing upon every available spot in which they
could even temporarily maintain themselves.^
Here then we have a group in which tliere is no
question of the means of dispersal ; and where the
difficulties that present themselves are not how the species
reached the remote localities in which they are now found,
but rather why they have not established themselves in
^ The following remarks by Dr. Richard Spruce, who has made a special
study of mosses and especially of hepaticre, are of interest. " From what
precedes, I conclude that no existing agency is capable of transporting the
germs of our hepatics of tropical type from the torrid zone to Britain, and
I venture to suppose that their existsnce at Killarney dates from the remote
period when the vegetation of the whole northern hemisphere partook of a
tropical character. If I am challenged to account for their survival
through the last glacial period, I reply that, granting even the existence of
a universal ice-cap down to the latitude of 40° in America and 50° in Europe,
it is not to be assumed that the whole extent, even of land, was perennially
entombed 'in thrilling regions of thick-ribbed ice,' Towards the southern
margin of the ice the climate was probably very similar to that of Greenland
and the northern part of Norway at the present day. The summer sun wouhl
have great power, and on the borders of sheltered fjords the frozen snow
would disappear completely, if only for a very short period, and I ask only
for a month or two, not doubting the capacity of our hepatics to survive in
a dormant state under the snow for at least ten months in the year, I liave
gathered mosses in the Pyrenees where the snow had barely left them on
August 2nd ; by September 25th they were re-covered with snow, anil would
not be again uncovered till the following year. The mosses of Killarney
might even enjoy a longer summer than this ; for the gulf-stream laves both
sides of the south-western angle of Ireland, and its tepid waters would exert
great melting power on the ice-bound coast, jireventing at the same time
any formation of ice in the sea itself." This i)assage is the conclusion of a
very interesting discussion on the distribution of hepatic^ in a paper on
*'A New Hepatic from Killarney," in the Journal of Botany, \oi. 25,
(Feb, 1887), pp. 33 — 82, in which many curious facts are given as to the
habits and distribution of these curious and beautiful little plants,
B B
370 ISLAND LIFE
many other stations Avhicli, so far as we can judge, seem
equally suitable to tliem. Yet it is a curious fact, that
the phenomena of distribution actually presented by this
group do not essentially differ from those presented by
the higher flowering plants which have apparently far
less diffusive 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 mutations as Ave have
just referred to ; and that thus the majority of plants are
afforded means of dispersal which are usually sufficient
to carry them into all suitable localities on the globe.
Hence it follows that their actiud existence in such
localities depends mainly upon vigour of constitution and
adaptation to conditions just as it does in the case of the
lower and more rapidly diffused groups, and only partially
on superior facilities for diffusion. This important principle
will be used further on to afford a solution of some of the
most difficult problems in the distribution of plant hfe.^
Concluding Bcmarks on the Peculiarities of the British
Fauna and Flora. — The facts, now I believe for the first
time brought together, respecting the peculiarities of the
British fauna and flora, are sufficient to show that there is
considerable scope for the study of geographical distribu-
tion even in so apparently unpromising 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 with the adjacent continent is not altogether
correct. Among birds Ave have undoubted peculiarities in
at least three instances ; peculiar fishes are much more
numerous, and in this case the fact that the Irish species
1 While these pages are passing through the press I am informed by my
friend Mr. W. H. Beeby that in the Shetland Isles, where he has been
collecting for five summers, he has found several plants new to the British
flora, and a few altogether undescribed. Among these latter is a very
distinct species of Hieracium {H. Zetlandicum), which is quite unknown
in Scandinavia, and is almost certainly peculiar to the British Islands.
Here we have another proof that entirely new species are still to be dis-
covered in the remoter portions of our country.
CHAP, xvr THE BRITISH ISLES 371
are almost all diiferent from the Britisli, and those of the
Orkneys distinct from tliose of Scotland, renders it almost
certain that the great majority of the iifteen peculiar
Britisli iishes are really peculiar and will never be found
on the European Continent. The mosses and Hepatica^
also have been sufficiently collected in Europe to render
it pretty certain that the more remarkable of the peculiar
British forms are not found there ; why therefore, it may
be well asked, slioidd there not be a proportionate number
of peculiar Britisli insects ? It is true that numerous
species have been first discovered in Britain, and, sub-
sequently, on the continent ; but we have many species
which have been known for twenty, thirty, or forty years,
some of which are not rare with us, and yet have never
been found on the continent. We have 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, certainly, do not exist
on our jDrincipal island which has been so very thoroughly
worked. Analogy, therefore, would lead us to conclude
that many other species or varieties would exist on our
islands and not on the continent ; and when w^e find tliat
a very large number (150) in three orders only, are so
recorded, we may I think be sure that some considerable
portion of these (though how many w^e 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, wdiich
are so excessively varied and abundant, wdiich present so
many isolated forms, and which, even on continents, afford
numerous examples of very rare species confined to re-
stricted areas, that we should have tlie best chance of
meeting witli every degree of rarity down to the point of
almost complete extinction. But we know that in all
parts of the w^orld islands are the refuge of species or
groups which have become extinct elsewhere; and it is
therefore in the highest degree probable that some species
which have ceased to exist on the continent should be
preserved in some part or other of our islands, especially
BB 2
372 ISLAND LIFE part ii
as these present favourable climatic conditions sucli as do
not exist elsewhere.
There is therefore a considerable amount of harmony
in the various facts adduced in this chapter, as well as a
complete accordance Avith what the laws of distribution
in islands would lead us to expect. In proportion to the
species of birds and fresh-water fishes, the number of
insect-forms is enormously great, so that the numerous
species or varieties here recorded as not yet known on the
continent are not to be wondered at; while it would,
I think, be almost an anomaly if, with peculiar birds and
fishes there were not a fair proportion of peculiar insects.
Our entomologists should, therefore, give up the assump-
tion, that all our insects do exist on the continent, and
will some time or other be found there, as not in accordance
either with the evidence or the probabilities of the case ;
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 interest. 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 ?
CHAPTER XVII
BORNEO AND JAVA
Position and Physical Features of Borneo— Zoological Features of P>orneo :
Mammalia— Birds— The Affinities of the Bornean Fauna— Java, its
Position and Physical Features— General Character of the Fauna of Java
— Ditferences Between the Fauna of Java and that of the other Malay
Islands— Special Relations of tlie Javan Fauna to that of the Asiatic
Continent— Past Geographical Changes of Java and Borneo— The
Philippine Islands— Concluding Remarks on the ]\Ialay Islands.
As a representative of recent continental islands situated
in the tropics, we will take Borneo, since, although
perhaps not much more ancient than Great Britain, it
presents a considerable amount of speciality; and, in its
relations to the surrounding islands and the Asiatic
continent, offers us some problems of great interest and
considerable difficulty.
The accompanying map shows that Borneo is situated
on the eastern side of a submarine bank of enormous
extent, being about 1,200 miles from north to south, and
1,500 from cast to west, and embracing Java, Sumatra,
and the Malay Peninsula. This vast area is all included^
within the 100 fathom line, but by far the hirger part ot
it—from tlic Gulf 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
MAP Oy BORNEO AND JAVA, SHOWING THE GREAT SUBMARINE BANK OF SOUTH-EASTERN ASIA.
The light tint sliows a less depth than 100 fathoms.
The figures show the dei>th of the sea in fathoms.
cH.vr. XVII BORNEO AND JAVA 376
Peninsula is about 350 miles, and it is nearly as far from
Sumatra and Java, while it is more than 600 miles from
the Siamese Peninsula, opposite to which its long northern
coast extends. There is, I believe, nowhere else upon
the globe, an island so 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 this large
island.
The internal geography of Borneo is somewhat peculiar.
A large portion of its surface is lowland, consisting of great
alluvial valleys which penetrate far into the interior ; while
the mountains except in the north, are of no great
elevation, and there are no extensive plateaux. A
subsidence of 500 feet would allow the sea to fill the great
valleys of the Pontianak, Banjarmassing, and Coti rivers,
almost to the centre of the island, greatly reducing its
extent, and causing it to resemble in form the island of
Celebes to the east of it.
In geological structure Borneo is thoroughly continental,
possessing formations of all ages, with basalt and crystalline
rocks, but no recent volcanoes. It possesses vast beds of
coal of Tertiary age ; and these, no less than the great
extent of alhivial deposits in its valleys, indicate great
changes of level in recent geological times.
Having thus briefly indicated those jDhysical features of
Borneo Avhich are necessary for our inquiry, let us turn to
the organic world.
Neither as regards this great island nor those wliicli
surround it, have we the amount of detailed information in
a convenient form that is required for a full elucidation of
its past history. We have, however, a tolerable acquaint-
ance with the two higher groups — mammalia and birds,
both of Borneo and of all the surrounding countries, and
to these alone will it be necessary to refer in any detail.
The most convenient course, 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, Avith the- main conclusions to which they
point ; and then to discuss the mutual relations of some of
ISLAND LIFE fAiir ii
the adjacent islands, and the series of geographical changes
that seem required to explain them.
Zoological Features of Borneo.
Mammalia. — Nearly a hundred and forty species of
mammalia have been discovered in Borneo, and of these
more than three-fourths are identical with those of the
surrounding countries, and more than one half with those
of the continent. Among these are two lemurs, nine
civets, five cats, five deer, the tapir, the elephant, the
rhinoceros, and many squirrels, an assemblage which could
certainly only have reached the country by land. The
following species of mammalia are supposed to be peculiar
to Borneo : —
QUADRUMANA.
13.
SciuriLs whitehead!. (Th.) Kini
1.
Simia morio. A small orang-
Balu.
utan with large incisor teeth.
14.
, , everetti.
2.
Hylobates niulleri.
15.
Rheithrosciurus macrotis.
3.
Nasalis larvatus.
16.
Hystrix crassispinis.
4.
Semnopitheciis rubicundus.
17.
Trichys guentheri.
5.
, , chrysomelas.
18.
Mus infraluteus.(Th. )Kini Balu.
6.
, , frontatus.
19.
„ alticola. (Th.) Kini Balu.
7.
,, hosei. (Thomas.)
Insectivora.
Kini Balu.
20.
Tupaia splendidula.
Carnivora.
21.
,, minor.
8.
Herpestes semitorqnatus.
22.
, , dorsalis.
9.
Felis badia.
23.
Dendrogale murina.
10.
Ungulata.
Sus barbatns.
24.
25.
Chiroptera.
Yesperugo stenopterus.
, , doriffi.
Rddentia.
26.
Cynopterus brachyotus.
11.
Pteromys phreomelas.
27.
,, lucasii.
12.
Sciurus jentinki. (Th. ) Kini
28.
, , spadiceus.
Balu.
29.
Hipposideros dorise.
Of the twenty-nine peculiar species here enumerated
it is possible that a few may 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 ; Rheithrosciurus, a peculiar form of squirrel ; and
Trichys, a tailless porcupine. These peculiar forms do not,
however, imply that the separation of the island from the con-
tinent is of very ancient date, for the country is so vast and
CHAr. XVII BORNEO AND JAVA 377
SO much of the once connecting land is covered witli water,
that the amount of speciality is hardly, if at all, greater
than occurs in many continental areas of equal extent and
remoteness. This will be more evident if we consider that
Borneo is as large as the Indo-Chinese Peninsula, or as the
Indian Peninsula south of Bombay, and if either of these
countries were separated from the continent by the
submergence of the whole area north of them as far as the
Himalayas, they would be found to contain quite as many
peculiar genera and species as Borneo actually does now.
A more decisive test of the lapse 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 as the tailed monkeys and
the numerous S([uirrels. These relationships, however, are
best seen among the birds, which have been more
thoroughly collected and more carefully studied than the
mammalia.
Birds. — About 580 species of birds are now known to
inhabit Borneo, of wdiich 420 species arc land-birds.^ One
hundred and eight species are supposed to be peculiar to
the island, and of these one half have been noted, either by
Count Salvadori or Mr. Everett, as being either representa-
tive species of, or closely allied to birds inhabiting other
islands or countries. The majority of these are, as might
be expected, allied to species inhabiting the surrounding
countries, especially Sumatra, the Malay Peninsula, or Java,
a smaller number liaving their representative forms in the
Philippine Islands or Celebes. But there is another group
of eight species Avhose nearest allies are found in such
remote lands as Ceylon, North India, Burma, or China.
These last have been indicated in the following list by a
double star (**) while those which are representative of
forms found in the immediately surrounding area, and arc
in many cases very slightly differentiated from tlirir allies,
are indicated by a- single star (*).
1 III llu" lirst edition of this work the mnnbcrs uno 100 and ;M0,
sliowing tlif ^rcat increase of our kiiowied^'o durin*,' tlio last ton years,
cliiefly owing to the researches of Mr. A. II. Everett in Sarawak and Mr.
John "Whitehead in Nortli Borneo and the <Meat Jiiuiintain Kiiii liahi.
378
ISLAND LIFE
List of Birds which are supposed to be peculiar to Borneo.
33.
34.
35.
36.
TuRDiDiE (Thrushes).
*Cittocincla suavis.
* ,, stricklanJi.
*Henicums borneensis.
*Phyllergates cinereicollis.
Buniesia superciliaris.
/.
8.
9.
10.
11.
**Cettia oreophila.
*Menila seebohmi.
**Geocichla aiirata.
**Myiophoneus borneensis.
Brachypteryx erythrogyna.
Copsychus niger.
T1MELIID.E (Babblin
^(;4arrulax schistochlamys.
Khinocichla treacheri.
Allocotops calvus.
**Stachyris borneensis.
Cyanodernia bicolor.
Chlorocharis a^niiliaj.
Androphihis accentor.
Malacoiiterum cinereocapilluni
**Staphidia everetti.
*lIerporius brunnescens.
Brachypodid^ (Bulbuls)
Thrushes).
22. *Mixornis borneensis,
23. * ,, montana.
24. *Turdinus canicapillus.
25.
26.
27.
28.
29.
30.
31.
atrigularis.
*Drymocataphus capistratoides.
Ptilophaga ruftventris.
, , leucogrammica.
*Corythocichla crassa.
*Turdinuhis exsul.
Orinthocichla whiteheadi.
*Heiiiixus connectens.
Criniger diardi.
* , , ruficrissus.
Tricophoropsis typus.
Oreostictes leucops.
41. Oriohis consobrinus.
43. Parus sarawakensis.
45. Pityriasis gyninocephala.
37. Rubigula luontis.
38. * :, paroticalis.
39. Chloropsis kinabaluensis.
40. * ., irridinucha.
ORluLlDJi (Orioles).
1 42. *Oriohis vuhieratus.
Parid^ (Tits).
1 44. *Dendrophik corallipes.
LANilDJi (Shrikes).
46. *Hyloterpe hypoxantha
63.
D1CRURID.E (Drongo-shrikes).
*Chibia borneensis. |
Campophagid^ (Caterpilkr-catchers).
€hlaniodych0era jetfreyi. ! 50. Pericrocotus cinereiguk
*Artamides normani. i
MuscicAPlD^ (Flycatchers).
**Hemichelidon cinereiceps.
*Rhinomyias gularis.
* , , ruficrissa.
Cryptolopha schwaneri.
montis.
57. Siphia coeruleata,
58. 3 , beccariana.
59. ,, clopurensis.
60. ,, obscura.
61. ,, everetti.
62. . , nigrogukris.
*Stoparola cerviniventris. i 62.
Xectarineidj:; (Sun-birds).
Arachnothera juliiv. 1
niAr. XVII BORNEO AND -lAVA 379
Dic^iD^ (Flower-peckers).
64. *Dioeuni inontit'oluiii. 1 67. **rrionochiIus evoretti.
65. * ,, pryeri. 6S. *Zosterops clara.
66. *Prionocliilus xantliu]>ygius. \
Ploceid.t-: (Weavers).
60. Chlonira boniecii.sis. | 70. Munia fuscan.s.
CuiiviujE (Crows).
71. *DeiKb'ocitta ciiiera.scens, I 73. *riaty.simirus alerrimus.
72. rissa jcffreyi. |
PiTTiDJi (Ground Thrushes).
74. Pitta berta3. | 77. *Pitta usheri.
75. ,, arcuata. i 7S. * ,, gi-anatiiia.
76. ,, baudi. | 79. * ,, schwaueri.
EuiiYLJ^MiDiE (Gapers).
80. Calyptoiiiena whiteheadi. |
C'YPSELlDiE (Swifts).
81. Cypselus lowi. |
PoDARCiiD.E (Frogmouths).
82. *ljatrac]iostoinus adspersus. |
Capkimulgid^ (Goatsuckers).
83. Caprinmlgus borueensis. [ 84. Caprinuilgus concretus.
PKiit.i; ("Woodpeckers).
85. *Jyngipicus aurautiiventris. I 87. *Micropternus badiosus.
86. ,, picatus. I 88. Sasia everctti,
ALCEDIN1D.E (Kingtishors).
89. *Pelargopsis Icucocephala. | 90. *Carcineutc.s nielanops.
Ti:oGu>:iDJ:; (Trogons).
91. llarpactcs whiteheadi. [
CucULiDJ:; (Cuckoos).
92. *Rhopodytes borneeiisis. [
Cai'ITonid.k (Harltets .
93. (.'yanops pulchcrriiaus. I 95. *M<'gahenia chr\'sopsis.
94. ,, uioiiticuhis. j
HLnoNiD.K (Owls).
96. lleteroscops luciie. I 97. *Syriiiuni leptogranimicum.
Fa \a OS I D.K ( Hawks, kc. ).
98. Si)ilurnis ]»allidus. ] 100. Micmhierax latifrons.
.99. *Accipiter nigrotiliialis. |
l^ilASFA.N I lu; ( Plieasants ;.
101. Polyplectron schlierniacheri. | 103. *ArgUbianus grayi.
102. Lobiophasis bul-weri. 1 101. *Euplocainus pyiionotus.
380 ISLAND LIFE part ii
Tetraonid^ (Grouse, &c. ).
105. Bambusicola hyperythra. I 107. Hsematortyx sanguiniceps.
106. ,, erythrophrys. |
Rallid^ (Rails). -
108. Rallina nifigenys. 1
Representative forms of the same character as those noted
above are found in all extensive continental areas, but they
are rarely so numerous. Thus, in Mr. Elwes' paper on the
"Distribution of Asiatic Birds," he states that 12-5 per
cent, of the land birds of Burmah and Tenasserim are
peculiar species, whereas we find that in Borneo they are
about 25 per cent., and the difference may fairly be
imputed to the greater proportion of slightly modified
representative species due to a period of complete
isolation. Of peculiar genera, the Indo-Chinese Pen-
insula has one — Ampeliceps, a remarkable yellow-crowned
starling, with bare pink-coloured orbits ; while two others,
Temnurus and Crypsirhina — singular birds allied to the
jays — are found in no other part of the Asiatic continent
though they occur in some of the Malay Islands. Borneo
has seven peculiar genera of passeres,^ as well as
Haematortyx, a crested partridge; and Lobiophasis, a
pheasant 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 formerly thought to be peculiar, are
said to have been discovered also in Sumatra.
The insects and land-shells of Borneo and of the sur-
rounding countries are too imperfectly known to enable us
to arrive at any accurate results with regard to their distri-
bution. They agree, however, with the birds and mammals
in their general approximation to Malayan forms, but the
number of peculiar species is perhaps larger.
The proportion here shown of less than one -fourth
peculiar species of mammalia and fully one-fourth peculiar
species of land-birds, teaches us that the possession of the
power of flight affects but little the distribution of land-
1 These are Allocotops, Clilorocliaris, Aiulrophilus, and Ptilopyga,
among the Timeliidre ; Tricophoropsis and Oreoctistes among the Brachy-
podidce ; Chlamydochcera among the Campophagidffi.
THAP. XVII BORNEO AND JAVA 381
animals, and gives us confidence 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
if we consider the wide range of certain groups of powerful
flight — as the birds of prey, the swallows and swifts, the
king-crows, and some others, we shall be forced to con-
clude that the majority of forest-birds are restricted by
even narrow watery barriers, to an even greater extent
than mammalia.
The Ajfinitics of the Borncan 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 1,500 miles apart — as
far as from Madrid to Constantinople, or from the Missouri
valley to California. In such an extent of country we
always meet with some local species, and representative
forms, so that we hardly require any great lapse of time as
an element in the production of the peculiarities we actually
find. So far as the forms of life are concerned, Borneo, as
an island, may be no older than Great Britain ; for the
time that has elapsed since the glacial epoch would be
amply sufficient to produce such a redistribution of the
species, consequent on their mutual relations being dis-
turbed, 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 order to understand what these changes
probably were, we must give a brief sketch of the fauna of
Java, the peculiarities of which introduce a new element
into the question we have to discuss.
382 ISLAND LIFE
PART II
Java.
The rich and beautiful island of Java, interesting alike
to the jDolitician, the geographer, and the naturalist, is
more es}3ecially attractive to the student of geographical
distribution, because it furnishes hhn with some of the
most curious anomalies and difficult problems in a place
where such would be least expected. As Java forms
with Sumatra one almost unbroken line of volcanoes and
^'o]canic mountains, interrupted only by the narrow Straits
of Sunda, we should naturally expect a close resemblance
between the productions of the two islands. But in point
of fact there is a much greater difference between them
than between Sumatra and Borneo, so much further apart,
and so very unlike in physical features.^ Java differs from
the three great land masses — Borneo, Sumatra, and the
Malay Peninsula, far more than either of these do from
each other ; and this is the first anomaly we encounter.
But a more serious difficulty than this remains to be stated.
Java has certain close resemblances to the Siamese Penin-
sula, and also to the Himalayas, which Borneo and Sumatra
do not exhibit to so great a proportionate extent ; and
looking at the relative position of these lands respectively,
this seems most incomprehensible. In order fully to
appreciate the singularity and difficulty of the problem, it
will be necessary to point out the exact nature and amount
of these peculiarities in the fauna of Java,
General Character of the Fauna of Java. — If we were only
to take account of the number of peculiar species in Java,
and the relations of its fauna generally to that of the
surrounding lands, we might pass it over as a less interest-
ing island than Borneo or Sumatra. Its mammalia
(ninety species) are nearly as numerous as those of Borneo,
but are apparently less peculiar, none of the genera and
only five or six of the species being confined to the island.
In land-birds it is decidedly less rich, having only 300
species, of which about forty-five are peculiar, and only one
^ In a letter from Darwin he says : — "Hooker writes to me, ' Miguel has
been telling me that the flora of Sumatra and Borneo are identical, and
that of Java (luite different. ' "
;HAr. XVII BORNEO AND JAVA
or two belong to peculiar genera ; so that here again the
amount of speciality is considerably less than in Borneo.
It is only when we proceed to analyse the species of the
Javan fauna, and trace their distribution and affinities, that
we discover its interesting nature.
Difference Between the Fauna of Jeiva and that of the other
qrcat Maleiy IsJaneJs. — Comparing the fauna of Java with
that which may be called the typical ^Malayan f\\una as
exhibited in Borneo, Sumatra, and the Malay Peninsula,
w^e find the following differences. No less than thirteen
genera of mammalia, each of which is known to inhabit at
least two, and generally all three, of the above-named
Malayan countries, are totally absent from Java ; and
they include such important forms as the elephant, the
tapir, and the Malay bear. It cannot be said that this
difference depends on imperfect knowledge, for Java is one
of the oldest European settlements in the East, and has
been explored by a long succession of Dutch and English
naturalists. Every part of it is thoroughly well known,
and it would be almost as difficult to find a new^ mammal
of any size in Europe as in Java. Of birds there are
twenty-five genera, all typically Malayan and occuning 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, hornbills, cuckoos, parrots,
pheasants, and partridges, as impossible to have re-
mained undiscovered in Java as the large mammalia above
referred to.
Besides these absent genera there are some curious
illustrations of Javan isolation in the S2:)ecies ; there being
several cases in which the same species occurs in all three
of the typical Malay countries, while in Java it is
represented by an allied species. These occur chiefly
among birds, there being no less than seven species which
are common to the three great Malay countries but are re-
presented in Java by distinct though closely allied species.
From these facts it is impossible to doubt that Java has
had a history of its own, quite distinct from that <>f the
other portions of the Malayan area.
384 ISLAND LIFE part ii
S'pecial Relations of the Javan Fauna to that of the Asiatic
Continent. — These relations are indicated by comparatively
few examples, but tliey are very clear and of great im-
portance. Among mammalia, the genus Helictis is found
in Java but in no other Malay country, though it inhabits
also North India; while two species, Rhinoceros javanicus
and Zepits hiirgosa, are natives of Indo-Chinese countries
and Java, but not of typical Malaya. In birds there are
five genera or sub-genera — Zoothera, Notodela, Crypsirhina,
Allotrius, and Cochoa, which inhabit Java, the Himalayas,
and Indo-China, all but the last extending south to
Tenasserim, but none of them occurring in Malacca,
Sumatra, or Borneo. There are also two species of birds
— a trogon {Haiyactcs oreskios), and the Javanese peacock
{Favo nmticus), which inhabit only Java and the Indo-
Chinese countries, the former reaching Tenasserim and the
latter Perak in the Malay Peninsula.
Here, then, we find a series of remarkable similarities
between Java and the Asiatic continent, quite independent
of the typical Malay countries — Borneo, Sumatra, and the
Malay Peninsula, which latter have evidently formed one
connected land, and thus appear to preclude any in-
dependent union of Java and Siam.
The great difficulty in explaining these facts is, that all
the required changes of sea and land must have occurred
within the period of existing species of mammalia.
Sumatra, Borneo, and Malacca have, as we have seen, a
great similarity as regards their species of mammals and
birds, while Java, though it differs from them in so curious
a manner, has no greater degree of speciality, since its
species, when not Malayan, are almost all North Indian or
Siamese.
There is, however, one consideration which may help us
over this difficulty. It seems highly probable that in the
equatorial regions species have changed less rapidly than
in the north temperate zone, on account of the equality
and stability of the equatorial climate. We have 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 con-
I
CHAP. XVII BORNEO AND JAVA 385
ditioiis, with the migrations and crowding together that
must have been their necessary consequence. But in the
lowlands, near the equator, these changes would be very
little if at all felt, and thus one great cause of specific
modification would be wanting. Let us now see whether we
can sketch OTit a series of not improbable changes which
may have brouglit about the existing relations of Java and
Borneo to the continent.
Past GeograjiMcal Changes of Java and Borneo. —
Although Java and Sumatra are mainly volcanic, they are
by iKj means wholly so. Sumatra possesses in its great
mountain masses ancient crystalline rocks with much
granite, while there are extensive 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 products of their
eruptions. In Java either the fundamental strata were
less extensive and less raised 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 the relics
of a formation destroyed by denudation or covered up by
volcanic deposits. In the southern part of Java, however,
there is an extensive range of low mountains, about 3,000
feet high, consisting of basalt with limestone, apparently
of Miocene age.
During this last named period, then, Java would have
been at least 3.000 feet lower than it is now, and such a
dejDression 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 islanils
with the continent. This may have continued till the
glacial period of the northern hemisphere, during the
severest part of which a few Himalayan species of birds
and mammals may have been driven southward, and
» "Oil the Geolorrv of Sninntrn," l»y M. I?. D. :\r. Vi'vlwk. Oeohciiral
c c
ISLAXD LIFE part ii
have ranged over suitable portions of the whole area. Java
then became separated by subsidence, and these species were
imprisoned in the island ; while those in the remaining
part of the Malayan 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 Borneo and Sumatra, in which a few other
Indian or Indo-Chinese forms have been retained, but prob-
ably leaving.tlie Malay Peninsula as a ridge between
them as far as the islands of Banca and Biliton. Other
slight changes of climate followed, when a further subsi-
dence separated these last-named islands from the Malay
Peninsula, and left them with two or three species which
have since become slightly modified. We may thus
explain how it is that a species is sometimes common to
Sumatra and Borneo, while the intervening island (Banca)
possesses a distinct form.^
In my Geographical Disirihution 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 ; but a fuller consideration of the influence of
changes of chmate on the migi^ation of animals, has led me
to the much simpler, and, I think, more probable, explan-
ation above given. The amount of the relationship
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 distinct and indisputable to be ignored ; and a
change of climate which should drive a portion ^ of the
Himalayan fauna southward, leaving a few species in Java
and Borneo from which they could not return owing to the
subsequent isolation of those islands by subsidence, seems
1 Pitta megao^hyncMcs (Bancsi) allied to P. hmchyurus (Borneo, Sumatra,
Malacca) ; and Pitta hanglcanus (Banca) allied to P, sordidus (Borneo and
Sumatra).
m.Kv. XVII THE PITILIPPIXES 387
to hi) a cause exactly ada^itcd to produce tlie kind
and amount of affinity between i\io^o dist;nit counti-ies
that actually exists.
Thk Philippine Islands-.
A general account of the fauna of these islands, and of
their biological relations to the countries which form the
subject of this cha^jter, has been given in my Grographiccd
Distrihiitioti of Animah, Vol. I. pp. 345-349 ; but since
the publication of that work considerable additions have
been made to their fauna, having the effect of somewhat
diminishing their isolation from the other islands. Four
genera have been added to the terrestrial mammalia — Croci-
dura, Felis, Pteromys, and Mus, as well as two additional
squirrels ; wliile the black ape {Cynojnthccus niger) has
been struck out as not inhabiting the Philippines. This
brings the true land mammalia to twenty-one species, of
which fourteen are peculiar to the islands ; but to these we
must add no less than thirty-three species of bats of which
only ten are peculiar.^ In these estimates the Palawan
^ The following list of the mammalia of the Philippines and the Sulu
Islands lias been kindly furnished me by ]\Ir. Everett.
QuADRUMANA. lt>. Crociduraedwanlsiaim. rcouliar
1. Macacus cynomolgus. ,^ S]iccie.s.
2. Tai-sius speetnnn. -^- Dendrogale sp.
,, -1. Galeopithecus plnlippinonsis. Pecnhar
Caunivora. spocios.
?.. Vivcrra tangaluiiga. Chiropterx
4. Paradoxurns philippinensis. Also in ' " '
Palawan. --• Ptcropus Icucopterus.
;'). Fflis bongalensis. In Xegvos Island. -•'• ,, edulis.
,, •_'4. ,, hyponielamis.
ti. Bnliahis niindorensis. Peculiar species. 0^5, Xantharpyia aniplexicaule.
7. Ccrvus philippinus. Peculiar species. 97. Cvnopterus marginatus.
s. ,, alfredi. Pecnliar species. og^ ' ^^ jagorii. Peculiar species.
9. ',, nigricans. Peculiar species. 29. Carponyeteris australis.
10. „ pseudaxis. Sulu only. Proli- ;]o. Rhinolophus Inctus.
ably introduced. ;jl. ,, philippinensis. Peculiar
11. Sns marchesi. Peculiar species. species.
Rodentia. 32. Rhinolophus rufns. Peculiar species.
,-.Scl„n,s i,l,i.ippi„o„s<.. r,c,li,v S: "■'•l-'f' "■<""'J,^«i.. p«mi„,
«PCCies. «npcies
13. Scinvus -^;^,^^-'lj^;^^-!-- ,^.,,. ... HiiUsi'leros larvatus.
danaoaildSsUa,,. ^'^- ,,'.'., «^««""'-^- ^•'^">'''"-
JJ: SjJfSpU;;;"'"^' ^^^"^^^^^^--^ .7. imUid^-os coronams. Peculiar
17. „ everetti. Peculiar species. .,8. HinSeros biclor.
Insectivora. ;^f) Mcgademia spasnia.
1*^. Crocidura Inzoniensis. Peculiar 40. Vesperngo pachypns.
species. II. .. tennis.
c c 2
?,88 ISLAND LIFE
oToup lias been omitted as these islands contain so many
Bornean species that if included they obscure the special
features of the fauna.
Birds. — The late Marquis of Tweeddale made
a special study of Philippine birds, and in 1873 pub-
lished a catalogue in the Transactions of the Zoological
Society (Vol. IX. Pt. 2, pp. 125-247). But since that date
large collections have been made by Everett, Steere, and
other travellers, the result of which has been to more than
double the known species, and to render the ornithological
fauna an exceedingly rich one. Many of the Malayan
p-enera which were thought to be absent when the first
edition of this work w^as published have since been dis-
covered, among wdiicli are Phyllornis, Criniger, Diceum,
Prionochilus, and Batrachostomus. But there still remain
a large number of highly characteristic Malayan genera
whose absence gives a distinctive feature to the Philippine
bird fauna. Among these are Tiga and M^iglyptes,
genera of woodpeckers ; Phoenicophaes and C-entropus, re-
markable cuckoos ; the long-tailed paroquets, Palteornis ;
all the genera of Barbels except Xantholgema ; the small
but beautiful family Euryla^midse ; many genera allied to
Timalia and Ixos ; the mynahs, Gracula ; the long-tailed
flycatchers, Tchitrea ; the fire-backed pheasants, Euploca-
mus ; the argus pheasants, the jungle-fowl, and many others.
The following tabular statement will illustrate the ra])id
growth of our knowledge of the birds of the Philippines: —
I I '
Laiid-hirds. Watov-Wrds. I Tolal.
Lord Tweeddale's Catalogue (1873)
Mr. Wardlaw Ramsay's List (1881)
158 60
265 75
218
340
Mr. Everett's MSS. List of Additions (1891); 370 102 \ 472
The number of peculiar species is very large, there being
about 300 land and fortv-two water birds, which are not
42. Vesperugo abramus. 4S. Kerivoiila pellucida. reculiar species,
43. Nycticejus kuhlii. 40. ,, jagorii. Peculiar species.
U. Vespertilio macrotarsiis. Peoiiliar 50. Minioptenis schreibersii.
species. Til. ,, tristis. Peculiar species,
45. Vespertilio capaccinii. 52. Einballonura monticola.
46. Harpiocephalns cyclotis. 5.3. Taphyzous melanopogon.
47. Kerivoiila hardwickii. 54. Nyctinomus plicatns.
(.|,vi.. xvii THK rilUJlMMXl'S. 380
known to occur bi-yond tlie gToup. We have liciv, still more
pronounced than in the case of Borneo, the reniaikable
fact of the true land birds presenting a larger amount of
speciality than the land niannnals ; for while more than
four-fifths of the birds are peculiar, only a little more
than half the mammals are so, and if we excludi.' the bats
only two-thirds.
The general character of the fauna of this gioup of
islands is evidently the result of their physical conditions
and geological history. The Philippines are almost sur-
rounded 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 Sulu
Islands. Two small groups of islands, the Bashees and
Babuyanes, have also afforded a partial connection with the
continent by way of Formosa. It is evident that the
Philippines once formed part of the great Malayan exten-
sion of Asia, but that they w^ere separated considerably
earlier than Java ; and having been since greatly isolated
and much broken up by volcanic disturbances, their species
have for the most part become modified into distinct local
forms, representative species often occurring in the different
islands of the group. 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. Their
comparative poverty in genera and species of the mammalia
is perhaps due to the lact that they have been subjected
to a great amount of submersion in recent times, greatly
reducing their area and causing the extinction of a con-
siderable portion of their fauna. This is not a mere
hypothesis, but is supported by direct evidence ; for I am
iiiformed by Mr. Everett, who has made extensive explora-
tions in the islands, that almost everywhere are found large
tracts of elevated coral-reefs, containing shells similar to
those living in the adjacent seas, an indisputable ]m)of of
recent elevation.
GondudiiKj RanarL^ on the Malai/ MaiuU. — Tliis com-
pletes our sketch of the great Malay islands, the seat of
the tyi)ical Malayan fauna. It has been shown that the
peculiarities presented l)y the individual islands may be all
390 1SLA^'D LIFE fAiiT li
sufficiently well explained by a very simple and com-
paratively unimportant series of geograpliical changes, com-
bined 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 conti-
nent, 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 specialisation
of so many peculiar types, the Philippines were first separ-
ated ; then at a considerably later period Java ; a little
later Sumatra and Borneo ; and finally the islands south of
Singapore to Banca and Biliton. This one simple series
of elevations and subsidences, combined with the changes
of climate already referred to, and such local elevations
and depressions as must undoubtedly have occurred,
jippears sufficient to have brought about the curious, and
at first sight puzzling, relations, of the faunas of Java and
the Philippines, as compared with those of the larger
islands.
We will now pass on to the consideration of two other
groups Avhich offer features of special interest, and which
will complete our illustrative survey of recent continental
islands.
CHAPTER XVITI
J A P A X AND F O R M O S A
Japan, its Position and Physical Features — Zoological Features of Japan —
Mammalia — Birds — 15irds Common to Great l^ritain and Ja])an — Birds
Peculiar to Japan — Japan Birds Recurring in Distant Areas — Formosa —
Physical Features of Formosa — Animal Life of Formosa — ]\Iammalia —
Land-birds Peculiar to Formosa — Formosan Birds Recurring in India or
]\Ialaya — Comparison of Faunas of Hainan, Formosa, and Japan —
General Remarks on Recent Continental Islands.
Japan.
The Japanese Islands occupy a wvy similar position on
the eastern shore of the great Euro-Asiatic continent to
that of the Britisli Islands on the western, except that
they ai-e about sixteen degrees further south, and having
a greater extension in latitude enjoy a more varied as
well as a more temperate climate. Their outline is also
much more irregular and their mountains loftier, th(^
volcanic peak of Fusiyama being l-t,l77 feet high ; \\\\\\i'
their geological structure is very complex, their soil
extremely fertile, and their vegetation in tUa highest
degree varied and beautiful. Like our own islands, too,
they are connected with the continent by a marine bank
less than a hundred fathoms below tlu^ surface — at all
events towards the north and south; but in the inter-
vening space the Sea of Japan opens out to a width of
six hundred miles, and in its central portion is very deep,
MAP OF JAPAN AND FORJIOSA (with depths iu fatboiUs).
LigM lint, sea under 100 fathoms. Medium tint, imder 1,000 fathoms. Lark tint over
1,000 fathoms. The fignreB show the depth in lathom.s. '
cuAi'. XVI 1 1 JAPAN AND FORMOSA 393
and this may be an indication that the connection between
the islands and the continent is of ratlier ancient date.
At the Straits of Corea the distance from the main^land
is about 120 miles, while at the northern extremity of
Yesso it is about 200. The island of Saghalien, however,
separated from Yesso by a strait only twenty-live miles
wide, forms a connection with Amoorland in about 52° N.
Lat. A southern warm current flowing a little t(j the
eastward of the islands, ameliorates their climate much
in the same way as the Gulf Stream does ours, and added
to their insular position enables them to support a more
.'^Topical vegetation and more varied forms of life than are
found at corresponding latitudes in China.
Zoological Features of Japan. — As we might ex^Dect from
the conditions here sketched out, Japan exhibits in all its
forms of animal life a close general resemblance to the
adjacent continent, but with a considerable element of
specific individuality ; while it also possesses some remark-
able isolated groups. Its fauna presents indications of there
having been two or more lines of migration at difterent
epochs. The majority of its animals are related to those
of the temperate or cold regions of the continent, 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 wdien a land communication existed between the
two continents over what are now the shallow seas of
Japan, Ochotsk, and Kamschatka. 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 wdien compared with
the rich fauna of China and Manchuria, but containing
monkeys, bears, deer, wild goats and Avild 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 zoologist since
the publication uf W)n Siebold's Fauna Japonica in 184'4,
394 ISLAXD LIFE
PAET II
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 must be remem-
bered that CoL'ea and Manchuria (the portions of the
continent opposite Japan) are comparatively little known,
Avhile in very few cases have the species of Japan and of
the continent been critically comi^ared. Where this has
been done, however, the peculiar species established by
the older naturalists have been in many cases found to bo
correct.
List or the Mammalia of the Japaxe.se Islands.
1. Macacus spcciosus. A luoukey witli riKliuieiitary tail and red face,
allied to the Barbaiy ape. It inhabits the island of Niphon up to
41° N. Lat., and has thus the most northern range of any living
monkey.
2. Pteropur, dasymallus. A peculiar fruit-bat, found in Xiu.siu Inland
only (Lat. 33° N.), and thus ranging further north of the eijuator
than any other species of the genus.
3. Khinolophus ferrum-equinum. The great horse-shoe bat, ranges from
Britain across Europe and temperate Asia to Japan. It is the II.
nippon of the Fauna Japonica according to Mr. Dobson's Monorjraplt
of Asiatic Bats.
4. K. minor. Found also in Burma, Yunan, Java, Borneo, c*v;c.
5. Vesperugo pipistrellus. From Britain across Europe and Asia.
6. Y. abramus. Also in India and C'liina.
7. V. noctula. From Britain across Europe and Asia.
8. \. molossus. Also in China.
9. Yespertilio capaccinii. Philippine Islands, and Italy ! This is /'.
'iiiacrodactylas of the Fauna Japonica according to Mr. Uobson.
10. ]Miniopterus schreibersii. Philippines, Burma, Malay Islands. This is
Vcspertilio hlepotis of the Fauna Japonica.
11. TaJpa wogura. Closely resembles the common mole of Europe, but
has six incisors instead of eight in the lower jaw.
12. Talpa miztti'a. Glintli. Alhcd to T. vjognra.
13. Urotrichus talpoidcs. A peculiar genus of moles contined to Jajjan.
An American sj)ecies lias been named Urofriclms gihsii, and ]\Ir.
Lord after comparing the two says that he "can find no difterence
whatever, either generic or specific. In shape, size, and colour, they
are exactly alike.'" But Dr. Giinther {P. Z. S. 1880, p. 441) states
that U. gihsii differs so much in dentition from the Japanese specifts
that it should be placed in a distinct genus, which he calls Neuro-
trichus.
14. Sorex myosurus. A shrew, found also in India and Malaya.
15. Sorcx dzi-nezumi.
16. S. umhriniis.
17. S. platycephahcs.
ciiAr. xviii JAPAN AND FORMOSA 395
18. Ursus arctos. vav. A peculiar variety of the European Lrowu bear
which inhabits also Anioorland and Kamschatka. It is tlu- Ursus
fcrox of the Fauna Japonica.
ll». Ursus jajwuiciis. A peculiar species allied to tlir Himalayan and For-
niosan species. Named U. tibctanus in the Fauna Japonica.
20. Mcles anakuma. Ditlers from the European and Siberian bad.i,'ers in
the form of the skull.
21. Mustda brachyura. A peculiar martin found also iu the Kurile
Islands.
22. Mustda nielauopus. The Japanese sable.
23. M. Japonica. A peculiar martin (See Proc. Zool. Soc. 186'), p. 1U4).
24. M. Sibericus. Also Siberia and China. This is the iV. itahi of the
Fauna Japonica according to Dr. Gray.
25. Lutroncdcsivhitdeyi. A new genus and species of otter (/''. Z. S. 1867,
p. 180). In the Fauna Japonica named Lutra vulgar h.
26. Enhydris marina. The sea-otter of California and Kamschatka.
27. Cams hochphijlax. According to Dr. Gray allied to Cuon sumatraaus
of the Malay Islands, and 0. alpivus of Siberia, if not identical with
one of them {P. Z. S. 1868, p. 500).
28. Vulpcs japonica. A peculiar fox. C'rt/u's r«J/;t'i' of Fauna Japonica.
29. Nyctcreutes proeyonoides. The racoon-dog of X. China and Anioor-
land.
30. Lcpus brachyurus. A peculiar hare.
31. Sciurus lis. A peculiar s([uirrel.
32. Ptcruinys Icacugenys. The white-cheeked Hying si[uirrel.
33. P. momocja. rerha])s identical with a Cambojan species (,/'. Z. S.
1861, p. 137).
34. Myoxus jaijoiiicus. A peculiar dormouse. J/, clegaus of the Fauna
Japonica; 31. javanicus, Schinz {Synopsis Mammal ium, ii. p. 530).
35. Mus argenteus. C'hina.
36. Mus vioJossians.
37. M. nezuiiii.
38. M. sjicciosus.
39. Ccrvus sika. A peculiar deer allieil to C. p-ycudaxi>> of Formosa and
C. mantchuricus of Northern China.
40. Ncmorhcdus crispa. A goat-like antelope allied to A', siiinalrcnus of
Sumatra, and N. Swinhoci of Formosa.
41. Sus icucomystax. A wild boar allied to S. iacra/ius v[' Formosa.
We thus find tliat iiu less tluiu twouty-six out (d" tlir
t'urty-uiie Japanese mammals are peculiar, and if \vc omit
the aerial bats (nine in number), as well as the niariiit'
sea-otter, we shall have I'emaining only thirty strictly land
mammalia, of which twenty-five are peculiar, or five-si.xths
of tlio whole. Nor does tliis represent all their sj)eciality ;
for we have a mole differing in its dentition from the
European mole ; another superficially resembling but ipiite
distinct froui an American species; a peculiar geuus of
otters; and an antelope wliose nearest alHes arc in
Formosa and Sumatra. Tlie im])(>rtance of these facts \s ill
396 ISLAND LIFE
be best understood when we have examined the corre-
sponding affinities of the birds of Japan.
Birds. — Owing to the recent researches of some English
residents we have probably a fuller knowledge of the birds
than of the mammalia ; yet the number of true land-birds
ascertained to inhabit the islands either as residents or
migrants is only 200, wliich is less tlian might be expected
considering the highly favourable conditions of mild climate,
luxuriant vegetation, and abundance of insect-life, and the
extreme riches of the adjacent continent, — Mr. Swinhoe's
list of the birds of China containing more than 400 land
species, after deducting all which are peculiar to the adjacent
islands. Only seventeen species, or about one-twelfth of
the Avhole, are now considered to be peculiar to Japan
proper ; while seventeen more are peculiar to the various
outlying small islands constituting the Benin and Loo Choo
gToujDs. Even of these, six or seven are classed by Mr. See-
bohm as probably sub-species or slightly modified forms of
continental birds, so that ten 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 of land-birds are also
found in Britain, or are such slight modifications of Britisli
species that the difference is only perceptible to a trained
<^»rnitholoo-ist. The followino- list of the land-birds common
to Britain and Jajian ]s very niterestnig, when avc consider
that these countries are separated by the whole extent of
the European and Asiatic continents, or by almost exactly
one-fourth of the circumference of the globe : —
Land Bikds Co.mmun tu Gkeat Bkitaix and Japan. ^
{Either Identical Species or Eeprcscatative siih-s'pecics. )
1 . (.Toklert'st Ji/yuhis crirtidun siih-ait. orientali^:
2. jNIarsh tit ParKs iKilustris .sub-.sp. japonicus.
o. Coal tit PariLs atcr siib-sp. 2Jcf.:ii!cnsis.
•1. Loiig-taikd tit Acrednla cauelata (the Mib-.sp. rusea is
r.iitisli\
^ Extracicil IVuiii Messrs. l>liiki,-lu]i and i'lAt-r's Caialvyac of Birds of
Japan {Ibis, 1878, ]>. 2U9), witli ]\lr. Sueliolinrs additions and corrections
in his Birds of the Japanese E/iqrirc 1890. Accidental stragglers are nut
reckoned as Britisli birds.
I
niAP. xviii .TA]>AX AND FORMOSA n07
Ti. Coiiiinoii cveopor Certhia familiar is.
('). Xutliat^'li Sitta curopa-a $i\\h-f<Y>. ainnrrnsis.
7. ('anion (Vinv Corvns coronr.
(S. Xnti'iMckr'i' ... Nucifraga canjorafarlcs.
y. ^Maii;i>it' Pica caudata.
10. Pallas.s' ^Tcv .slnikc Lanius cxcuhit.or ii\\^)-s\>. ■iii^fjnr.
U. "Waxwing AmjKlis garruliifi.
1 2. Grey wagtai 1 Motacilla. hoarula sub-sp, mdanopc.
Vi. Alpine Pipit Aviliais .ynnolcUa sub-sp. japonicufi.
1 4. Skylark Alauda arirnsis snb-sp. jajvrnii'a.
15. Common liawfincli Coccothormsfcs vulgaris.
16. Common ( 'ros.sbill Lo.ria earvirostra..
17. Siskin Fringilla spimis.
1 8. .Mealy rcdpol i • , , Hnaria.
19. Branibling ,, montifringilla.
20. Tree sparrow Pa-iser montanii.^.
21. Reed ])unting Bmbcrha^ scJucnio/liis sub.sp. palirs/rh.
22. Kustic bunting , , rustica.
23. Snow bunting , , nivalis.
24. Chimney swallow Hirundo rustiva x\\^^-^\i. giitturnli^.
2;>. Sand martin Cofyle ri2)aria.
26. Creat spotted woodp 'eker Picus major sub-sp. japonivus.
27. Les.ser spotted woodpecker ,, minor.
28. Wryneck Jynx torquiUa.
20. Hoopoe Upupa epopts.
30. Blue rock pigeon Cohimha livia.
.31 . Cuckoo Cuciilus canorns.
32. Kingfisher A Iccdo ispida sul>-s]i. h<^iiga,lensis.
33. Eagle owl Bubo maximus.
34. Snowy owl Surnia nydm.
3.5. Long-eared owl Strix otus.
36. Short-eared owl ,, hrachyotus.
37. Scops owl Scops scops.
38. Jer falcon Faho gyrfako.
39. Peregrine falcon , , picrcgrinvs.
40. Hobby ,, snhhvtco.
41. Merlin Falco a^salon.
42. Kestrel Tinniinculics alauda r ins sub-sp. japon iors.
43. Osprey Pandioii halidefus.
44. Honey-buzzard Pernis apivorus.
45. White-tailed eagle iraliactus albicilla.
46. Golden eagle Aquila chrysdctus.
47. Common i)uzzan I Jjuteo vulgaris sul>-sp, pluriiiprs.
48. Hen-harrier Circus cyaneus.
49. jMarsh-liarrier , , (vruginosus.
50. Go.s-hawk Astur palwnbarit/s.
51 . Sparrow-hawk Accipiter n isiis.
52. Ptarmigan Tetrao m utus.
53. Common quail Cofinniix comrmniis.
But even these fifty-three species by no means fairly
represent the amount of rrsrmhhnicc between Britain and
ISLAXD LIFE pap.t ti
JajDan as regards birds ; for there are also thrushes, robins,
stonechats, wrens, hedge-si^arrows, sedge-warblers, jays,
starlings, s^^^fts, goatsuckers, and some others, which,
though distinct Sjjccics from our own, have the same
general appearance, and give a familiar aspect to the
ornithology. There remains, however, a considerable body
of Chinese and Siberian species, which link the islands to
the neighbouring parts of the continent ; and there are
also a few which are Malayan or Himala3^an rather than
Chinese, and thus afford us an interesting ])roblem in
distribution.
The seventeen species and sub-species which are
altogether peculiar to Japan proper, 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
sieholdi) — has no close ally nearer than Burmah and the
Himalayas. In tbe following list the affinities of the species
are indicated wherever they liave been ascertained : —
List of the Species of Land Birds peculiar to Japan.
1. Accentor rahidufi. Nearl}^ allied to our hedge-sparrow, and less closely
to the Central Asian A. immaculatuR.
(la. Hypsi-pdcR amauroiis. Migrates to the Corea, otherwise peculiar.)
2. ZosteT02)s japonica. Allied to two Chinese species.
3. Ltisciniola pryeri.
4. Garridus japonicus. Allied to the Siherian and British Jays.
.5. Fringilla kmrarahiha. Allied to the Chinese greenfinch.
6. Emhcriza ciopsis. Allied to the E. Siberian Inmting E. cioidcs, of which
it may be considered a snb-sj)ecies.
7. Emhcrha ycssoensis. A distinct species.
8. ,, pcrsonaia. iV HXih-^-pecies of E. sjjodoccphala.
9. Gceinus mcolcera. A distinct species of green woodpecker.
10. Picus namiyci. Allied to a Forniosan species.
11. Treron sicholdi. Allied to T. sphenura of the Himalayas, and to a
Formosan species.
12. Carpopli-agct ianthina. A distinct species of fruit-pigi-on.
13. Buho blakistoni. Allied to a Philippine eagle-owl.
14. Scops semitorgues. A distinct species.
15. Phasianus versicolor. A distinct species.
16. ,, sceinmeringi. A distinct species.
17. ,, scintilhms. A sub-species of the last.
The large number of seventeen peculiar species in the out-
lying Benin and Loo Choo Islands is an interesting feature
of Japanese ornithology. The comparative remoteness of
II AP. XVIII JAPAN AND F0R:M0SA 399
these islands, their mild sub-tropical eliiuate and luxuriant
vegetation, and perhajis the absonce of vi).>lent storms and
their being situated out of the line of continental
migration, seem to be the conditions that have favoured
the specialisation of modified types ada])t(Ml to the new
environment,
Japan Bird>i Bccvrring in Didant Areas. — The most
interesting feature in the ornithology of Jajjan is, un-
doubtedly, the presence of several species which indicate
an alliance with such remote districts as the Himalayas,
the Malay Islands, and Europe. Among the peculiar
species, the most remarkable of this class are, — the fruit-
pigeon of the genus Treron, entirely unknown in (/hina,
but reappearing in Formosa and Japan ; the Hypsipetes,
whose nearest ally is in South China at a distance of
nearly 500 miles; and the jay (Garrulnsjaponicus), whose
near ally (G. glandarius) inhabits Europe only, at a
distance of 3,700 miles. But even more extraordinary are
the foll(~»wing non-peculiar species : — f^pizactus oricntalis, a
crested eagle, inhabiting tlie Himalayas, Formosa, and
Japan, but unknown in Southern or Eastern China ; Ccrylr
(/uttata, a spotted kingfisher, almost confined to the
Himalayas and Japan, though occurring rarely in Central
China ; and Halcyon coromanda, a brilliant red kingfisher
inhabiting Northern India, the Malay Islands to Celebes,
Formosa, and Japan. We have here an excellent illus-
tration of the favourable conditions whicli islands aftbrd
both for species Avhich else wli ere live further south
(Halcyon coroinanda), and for the preservation in isolated
colonies of species which are verging towards extinction ;
for such we must consider the above-named eagle and
kingfisher, both confined to a ^'ery limited area on the
continent, but surviving in remote islands. Referring to
our account of the birth, growth, and death of a species (in
Chapter IV.) it can hardly be doubted that the Ccrylc
guttata formerly ranged from the Himala3^as to Jai)an, and
has now almost died out in the intervening area owing to
geographical and physical changes, a subject which will ho
better discussed when we have examined the interesting
fauna of the island of Formosa.
400 ISLAXD LIFE part ii
The other orders 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 CTCogrcqoliiccd Bistrihution of Animals
(Vol I., pp. 227-281), and they sufficiently agree with the
birds and mammalia in showing a mixture of temjDerate
and tropical forms with a considerable .proportion of
peculiar species. Owing to the comparatively easy passage
from. the northern extremity of Japan through the island
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 peculiar 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 Jaj^an was finally separated from the
continent. How long ago this separation toolc ] lace we
cannot of course tell, but we may be sure it \,as 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 almost all our present knowledge
of it to a single man, the late Mr. Robert Swinhoe, who, in
his official capacity as one of our consuls 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 si^are 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 know-
ledge 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. Swinhoe's
own exertions during the twenty years of his service in
CHAP, xviii JAPAN AXJ) FORMOSA 401
that country. We possess, too, the furtlier advantag-e of
having the whole of the avaihible materials in these twd
classes collected together by Mr. Swinhoe himself after full
examination and comparison of specimens ; so that there is
])robably no part of the world (if we except Europe, North
America, and British India) of whose warm-blooded vertcj-
brates we possess fuller or more accurate knowledge than
we do of those of the coast districts of China and its
islands.^
Physical Fecdures of Forrnosa. — The island of Formosa is
nearly half the size of Ireland, being 220 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 8,000 feet in the south and 12,000 feet in
the northern half of the island, 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, combined with
its lofty mountains, gives it an unusual variety of tropical
and temperate climates. These circumstances are all
highly favourable to the preservation and development of
animal life, and from what we already know of its pro-
ductions, 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 tlie number and
variety of their higher animals. The outline map (at page
392) shows that Formosa is connected with the mainland
by a submerged bank, the hundred-fathom line including
it along with Hainan to the south-west and Japan on the
north-east ; while the line of two-hundred fathoms includes
also the Madjico-Sima and Loo-Choo Islands, and may,
peril a})s, mark uut approximately the last great extension
of the Asiatic continent, the submerc^ence of which isolated
these islands from the mainland.
Animal Life (f Foriiiosa. — We are at present ac(piainted
' Mr. Swinhoe died in October, 1877, at the early ai;e of forty-two. Ili.>
writings on natural history are chiefly scattered through the volumes of the
Proceedings of the Zoological Society aud The Ibis; the whole being sum-
marised in his Catalogue of the Manimals of South China and Fonnosa {P.
Z. S., 1870, p. 615), and his Catalogue of the Birds of China and its
Islands {P. Z. S., 1S71, l>. o'37 ).
D D
402 LSLA^'I) LIFE
with 35 species of mammalia, and 128 species of land-
birds from Formosa, fourteen of the former and forty-three
of the latter being peculiar, while the remainder inhabit
also some part of the continent or adjacent islands. This
yjroportion of peculiar species is perhaps (as regards the
bircls) the highest to be met A\dth in any island which can
be classed as both continental and recent, and this, in all
probability, implies that the epoch of separation is some-
what remote. It was not, however, remote enough to reacli
back to a time when the continental fauna was ^^ery
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, antelopes, 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 identical
with some still living elsewhere or very closely allied to
them. The birds exhibit analogous phenomena, with the
exception that we have here two peculiar and very inter-
estingf genera.
But besides the amount of specific and generic modifica-
tion that has occurred, we have another indication of the
lapse of time in the peculiar relations of a large j^roportion
of the Formosan animals, which show that a great change
in the distribution of Asiatic species must have taken
place since the separation 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
w^e shall have frequent occasion to refer to them.
List of the Mammalia ov Formosa. (The peculiar sx^ecies are i)rinted
in italics. )
1. Macacus cydopis. A rock-moukey more allied to M. rhesus of India
than to M. sandi-johannis of South China,
li. Fteropus formosus. A fruit-bat closely allied to the Japanese species.
Kone of the genus are found in China.
3. Vesperugo abramus. China.
4. Yespertilio formosus. Black and orange Bat. China.
5. Nyctinomus cestonii. Large-eared Bat. China, S. Europe.
6. Talpa insularis. A blind mole of a peculiar species.
vHxv. XVIII JAPAN AND FORMOSA 403
7. Sorex niunuu.s. Musk Rat. China.
8. Sorex sp. A shrew, uiuleseribed.
9. Erinaceus sp. A Hedgeliog, uudescribed.
10. Ursus tibetanus. Tlio Tibetan l^ear. Himalayas and Xurth ('liina.
11. Ildidia suhauraiitlaca. Tlie orange-tinted Tree Civet. Alliccl to //.
nlpalcnsis ot" the Himalayas more than to //. 'laosrhiUa o^ V\\\\\\i.
12. ]\rartes IhivigiUa, vai'. The yellow-neckod ^larten. India, ('hina.
Vj. Felis niaeroseelis. The elouded Tiger of Siam and ^lalaya.
14. Felis viverrina. The Asiatic wild Cat. Himalayas and Malacca.
15. Felis ehinensis. The Chinese Tiger Cat. China.
16. Viverricula malaccensis. Si)otted Civet. China, India.
17. Paguma larvata. Gem-laced Civet. China.
18. Sus takanus. Allied to the wild Pig of Japan.
19. Cervulus reevesii. Reeve's ]\Iiintjac. China.
20. Ccrvus 2)seuclaxis. Formosan Spotted Deer. Alliud to C. sika of
Japan.
21. Cervus sicliihuli. Swinhoe'sRusa Deer. Allied to Indian and Mala\an
species.
*22. Ncmorhcdiis sicinhoii. Swinhoe's Goat-antelope. Allied tu the species
of Sumatra and Japan.
'lo. Pos ehinensis. South China wild Cow.
24. ]\Ius bandieota. The Pandicoot Rat. Perhaps introduced from India.
25. Mus indicus. Indian Rat.
26. Mus coxinga. Spinous Country-rat.
27. Jfus canna. Silken Country-rat.
28. Mus losca. Brown Country-rat.
29. Sciurus castaneoventris. Chestnut-bellied Stiuirrel. China and
Hainan.
30. Seiurus m'elellandi. M'Clelland's Squirrel. Himalayas, China.
31. Sciuropterus kalccus^s. Small Formosan Flying Sqiiirrel. Allied to
S. albonujer of Nepal.
32. Fleroriiijs grancUs. Large Red Flying Squirrel. Allied to Himalayan
and I3ornean species. From North Formosa.
33. Pteromys jjcdorcdis. "White-breasted Flying Squirrel. From South
Formosa.
34. Lepus sinensis. Chinese Hare. Inhabits South China.
35. Manis dalmanni. Scaly Ant-eater. China and the Himalayas.
Tlie most interesting and suggestive feature connected
with these Formosan mammals is the identity or affinity
of several of them, with Indian or Malayan rather than
Avith Chinese species. We have the rock-mohki-y «>f
Formosa allied to the rhesus monkeys of India and
Burma, not to those of South China and Hainan. Tin;
tree civet {Ifdidis suhcmrcuUiaca), and the small trying
squirrel {Scmroj)terus kalccnsis), are both allied to Hima-
layan species. Swinhoe's deer and goat-antel()})e are
nearest to Malayan species, as are the red and wliite-
breasted Hying squirrels; while the fruit-bat, the wild pig^
I) I) '2
404 ISLAND LIFE
and the spotted deer are all allied to peculiar Japanese
species. The clouded tiger is a Malay species unknown
in China, 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 tlieir ancestral types must have ranged
over the intervening country as far as the Himalayas on
the west, Japan on the north, and Borneo or the Philip-
pines on the south ; and that after that event occurred,
the conditions were so materially changed as to lead to
the extinction of these species in Avhat are now" the coast
provinces of China, while they or their modified descend-
ants continued to exist in the dense forests of the
Himalayas and the Malay Islands, and in such detached
islands as Formosa and Japan. We will now see wdiat
additional light is thrown upon this subject by an exam-
ination of the birds.
Li.sT or THE Land liiiiDs pixuliar to Formosa.
TiTRDH).!-] (Thriulies).
1. Tardus albiccps. Allied to Chinese species.
Sylvidle (Warblers).
2. Cisticola tolitans. Allied to (J. achxenicult of India and China.
o. Ilcrhivox cantans. Sub-species of H. cantiUmis of K". China and
Japan.
4. Xotodda riiontium. Allied to X. Icaciira of the Himalayas ; no ally in
China.
TjMALiiD.t; (Babblers).
5. Pu)iiatorhliiiis nimicus. Allies in S. China and the Himalayas.
6. P. crythroencmis. Do. do.
7. Garrulax ruficeiM. Allied to G. albogularis of K. India aud East
Thibet, not to the species of S. China {G. sannio).
8. Janthociacla 'ptecilorliyncha. Allied to J. CKrulata oi i\\{i Himalayas.
Kone of the genus in China.
9. TrochaloiJteron taivanus. Allied to a Chinese species.
10. Alcippe tiwrrisoiiiana.^ Near the Himalayan ^. wz^fifc/Ji-/^'. None of
11. A. hrunn<:a. ] the genus in China.
12. ^ibia auricular is. Allied to the Himalayan S. caijlstrata. The genus
not known in China.
Fanurid^ (Bearded Tits, &c).
13. tSulJiora bulomachus. Allied to the Chinese S. sttfusa.
ViycLiDM (Dippers and Whistling Thrushes).
14. Jli/iupho/icus insiilaris. Allied to i)/. horsjieldi oiiionVa India.
riiA?. xvTii JAPAN AND FOR>rOSA 405
Partd^e (Tits).
1'). Parus iiispcra'Ais. Sub-spor-ios of A ninnfii-aJit o^ \]\i' lliiiinbivas ainl
East Thi])et.
It"). /'. rashtncicrnfrif^. Allioil to /*. ?yo'///.s of .Tapaii.
LKvrKHHin.r, illill Tits\
17. Lioinchlii stccrii. A poculiar ,i:,'tMius df a si>ocially Tliinnlnyaii family,
(juito nnknown in China.
Pvononotid.t: (Bull mis).
IS, Pycnoiiolufi (Sixtzixos) cinerelca-pillii^. Very iioav P. sTm,'/o,Yjur.<i of
China.
19. ITypsipefcfi nigern'mns!. Al]ic<l to Jf. caneohrr of A>isam, not to If.
inacrlrlhciuU of China.
OnroLiD.E (Oiioles).
20. Analclpufi ardcm. Allied to .■/. tmillii of tlio Himalayas ami Ti^nas-
sorini.
CAMPRPiiAfUD.Ti (Caterpillar Shrikes).
21. fJraucalus rex-pincfi. Closely allied to thf Indian -7. mncc'. Xo ally
in China,
Dicr.urjD.E (King Crows),
22. Chaptia hrauniana. Closely allied to C. ccnea of Assam, Xo ally in
China,
]\[rsciCAriD^E (Flycatchers ),
23. Cyornis rtvida. Allied to C rvhcculoidr.s o^ l\v\'v^.
ConviD.E (Jays and Crows).
24. Garruhis taivanuft. Allied to G-'. sinensis o{^. China.
25. Urocissa ccernlca. A very distinct .species from its Indian and Chinese
allies.
26. Dendrocittaformosfc. A snb-species of the Chinese A sinensis.
Ploceid^ (AVeaver Finches).
27. Muniaformosana. Allied to M. ruhronigra of India and Bnrmali.
Alaudid^ (Larks).
28. Alcmdasala. ) ^^..^ . ^^^^^^^ ^.^^.^^^^
29. A, v-attcrsi. \
PiTTlD-E (Pittas\
30. Pitlaorcas. Allied to P. ci/fr7ioj:)/cm of ]\Iala3'a and S. China.
Pkid.e (Woodpeckers).
31. Piois ins)ilaris. Allied to P. Icuconotus of Japan and Siberia.
AIeoat.-emid.e.
32. Megahcma nuchalL^. Allied to M. oorlii of Snmatra and ^f. inhcr of
Hainan. Xo allies in China.
CAPnTMULGiDiE (Goatsnckcrs),
33. Caprimnlrivs stirfo.uiis. A sub-species of C. monfirolns of India and
China.
406 ISLAXD LIFE
COLUMBIDiE (Pigpons).
•'^4, Trcron formoscc. Allied to IMalayan species,
35. S'phenoccrcv.^ sororinsi. Allied to Mala}' siDecies and to S. suholdi of
Japan. Xo allies of these two liirds inhabit China.
36. Chalcopha'psformosana. Allied to the Indian speeies whicli extends
to Tenasserim and Hainan.
Tetkaonid.t: (Gronse and Partridges).
37. Orcopcrdix crudigularis. A pecnliar genus of partridges.
38. Bamhnsieola sonorivox. Allied to the Chinese P>. tJwracka.
39. Arcoturnix rostraia. Allied to the Chinese A. hlal'i^fonii.
Pii ASIA N I D.i-: ( Phen sants).
40. Phasianus formosanus. Allied to P. iorquatus of China.
41. Fnplocamns sicinhou. A very pecnliar and beautiful siDecies allied to
the tropical fire-baeked plu-nsants. and to tho silver pheasant of
North Cliina,
Strigidte (Owls).
42. Athene pardalota. Closely allied to a Chinese species.
43. Ijcmpigins hamhroekii. Allied to a Chinese species.
This list exhibits to us the marvellous fact that more
than half the peculiar species of Formosau 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 wliich are not
Chinese. Two have their only near allies in Japan.
PerhaiDS more curious still are those cases in which,
though the genus is Chinese, the nearest allied species
is to be souo'ht for in some remote reo'ion. Thus w^e have
the Formosan babbler {Garrulax Qnifice2:>s) not allied to the
species found in South China, but to one inhabiting North
India and East Thibet ; while the black bulbul {Hypsiiictcs
nigcrrimvs), is not allied to the Chinese si^ecies 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 rather than Chinese, so that they offer examples
of discontinuous distribution somewhat analogous to wdiat
cuAV. xvTii JAPAT^ AND FORMOSA 407
we found to occur m Japan. Tliese are enumerated in
tlio following list.
Srr/'iEs OF BrRD>5 common to Formosa and India on ^Falaya, but not
FOUND IN China.
1, Siphla superciliaris. The Rufous-breasto«l Flvfatclior of tlio S.K.
Hiinalayns.
2. Halcyon coromainhi. Tho Great Rod Kingfislier of India, Mnlaya, and
Japan,
?>. Pt/Juuibi/fi jJit'^chricoJIis. Tho Darjoolinc; AVood-pigoon of the S. E.
Hiniahiyas.
•I. Turnix dussumieri. Tlie larger Button-quail of India.
.5. Spizaetus nipaUnsis. The Spotted Hawk-eagle of Xo]xil and A>;sani,
0. Lopliospiza trivirgata. The Crested Gos-hawk of tho ]\Ialay Islands.
7. Bulaca ncivarensis. The Brown AVood-owl of the Himalayas,
8, Strix Candida. The Grass-owl of India and ^lalaya.
The most interesting of tho above are the pigeon and
the flycatcher, both of Avhich are, so far as j^et known,
strictly confined to the Himalayan mountains and Formosa.
They thus afford examples of discontinuous specific
distribution exactly parallel to that of the great spotted
kingfisher, already referred to as found only in the
Himalayas and Japan.
Comparison of the Favnas of JIainan, Formosa, and
Jaimn. — The island of Hainan on the extreme south 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. Swinhoo), two of
which are close allies of Formosan species, while two others
are identical. Wo also find four species whose nearest
allies are in the Himalayas. Our knowledge of this island
and of the adjacent coast of China is not yet sufficient io
enable us to form an accurate judgment of its relations,
but it seems probable that it was separated from the
continent at, approximately, the same epoch as Formosa
and Japan, and that the special features of each of these
islands are mainly due to their geographical position.
Formosa, being more completely isolated than either of the
others, possesses a larger proportion of peculiar species of
birds, while its tropical situation and lofty mountain ranges
408 ISLA^^D LIFE
have enabled it to preserve an nmisua] number of Hima-
layan and Malayan forms. Japan, almost equally isolated
towards the south, and having a mucli greater variety of
climate as well as a much larger ai-ea, possesses about an
equal number of mammalia with Formosa, and an even
larger proportion of 2:)eculiar s^Decies. Its birds, however,
though more numerous are less peculiar ; and this is
probably due to the large number of species which migrate
northwards in summer, and find it easy to enter Japan
through the Kurile Isles or Saghalien.^ Japan too, is
largely peopled by those northern types which have an
unusually wide range, and which, being almost all migratory,
are accustomed to cross over seas of moderate extent.
The regular or occasional influx of these species jDrevents
the formation of special insular races, such as are almost
always i^roduced when a portion of the 2Dopulation of a
species remains for a considerable time completely isolated.
We thus have explained 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 Remarhs 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 termina^ting with Formosa, probably one
of the most ancient of the series, and which accord-
ingly 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 mainland,
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
^ Captain Blakiston lias sIioayh that the northern island — Yezo — is much
more temperate and less peculiar in its zoology than the central and southern
islands. This is no doubt dependent chiefly on the considerable change of
climate that occurs on passing the Tsu-garu strait.
niTAP. xvin .TAPAX AXD FORMOSA 409
specios die out ;iii(l ;\yr rc[)l;i('0(l l)y otlicrs, wliidi (|iiit('
figroos witli wliat tlio tlioory of cvolutioii assures iis nmst
liavo occuit(h|. On a continoiit, tlu? process of extiiirtion will
i^eiicrally take effect on tlie circninferencc of the area of
(listributioii, because it is there tliat the species comes into
contact witli such adverse conditions or competing forms
as prevent it from advancing furtliei\ A very sHght 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 some-
times happened) that the process of restriction of range by
adverse conditions may act in one direction only, and over
a limited district, so as ultimately to divide the specific
area into two separated parts, in each of which a portion
of the sj^ecies will continue to maintain itself. We have
seen that there is reason to believe that this has occurred
in a very few cases both in North America and in Northern
Asia. (Sec pp. 65-68.) But the same thing has certainly
occurred in a considerable number of cases, only it has
resulted in the divided areas being occupied by rcprcscntd-
iim formi^ instead of by the very same species. The cause
of this is very easy to understand. We have already shown
that there is a large amount of local variation in a
considerable number of species, and we may be sure that
were it not for the constant intermingling and inter-
crossing of the individuals inhabiting adjacent localities
tins tendency to local variation in adaptation to slightly
different conditions, would soon form distinct races. But
as soon as the area is divided into two portions the inter-
crossing is stopped, and the usual result is that tw^o closely
allied races, classed as representative 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 supposition that
theyare descendants of a parent form which once occupied an
area comprising that of both of them, — that this area 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.
410 ISLAND LIFE
PART II
Now, when the division of the area leaves one portion of
the species in an island, a similar modification of the
species, either in the island or in the continent, occurs,
resulting in closely-allied but distinct forms ; and such
forms are, as we have seen, highly characteristic of island-
faunas. But islands also favour the occasional preservation
of the unchanged species — a phenomenon which very
rarely occurs in continents. This is probably due to the
absence of competition in islands, so that the parent
species there maintains itself unchanged, while the con-
tinental portion, by the force of that competition, is driven
back to some remote mountain area, where it also obtains
a comparative freedom from competition. Thus may be
explained the curious fact, that the species common to
Formosa and India are generally confined to limited areas
in the Himalayas, or in other cases are found onlv in
remote islands, as Japan or Hainan.
The distribution and affinities of the animals of con-
tinental islands thus throws much light on that obscure
subject — the decay and extinction of species ; while the
numerous and delicate gradations in the modification of
the continental species, from perfect identity, through
slight varieties, local forms, and insular races, to well-
detined species and even distinct genera, afford an over-
whelming mass of evidence in favour of the theory of
" descent 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 peculiarities, and offer some most
curious prol)lems to the student of distribution.
CHAPTER XTX
AXrTENT CONTINEXTAL ISLANDS : THE MADAGASCAR GROrP
Romaiks on Anciont Continental Islands— rhysical Foaturcs of iMadagascar
—Biological Features of ]\Iadagascar— Mammalia — Reptiles— Relation
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 IMadagascar and India— Concluding Remarks on
" Lemuria ■'— The jNIascarene Islands — The Comoro Islands— The Sey-
chelles Archipelago— Birds of the Seychelles— Reptiles and Amphibia—
Freshwater Fishes— Land Shells— :Mauritius, Bourbon, and Rodrigu.>z—
Bii-as- Extinct liirds and their Probable Origin— Reptiles— Flora of
Madagascar and the Mascarene Islands— Curious Relations of ;^LlScarene
Plants— Endemic Genera of :Mauritius and Seychelles— Fragmentary
Character of the I^Iascarene Flora— Flora of :Madagascar Allied to that
of South Africa— Preponderance of Ferns in the ^lascarene Flora— Con-
(duding Remarks on the Madagascar Group.
We have now to consider the phenomena presented by a
very distinct class of islands — those which, ahhough once
forming part of a continent, have been separated from it at
a remote epoch Avhen its animal forms were very unlike
what they are now. Such islands preserve to us tlie
record of a by-gone world, — of a period when many of the
higher types had not yet come into existence and when
tlie distribution of others was very difterent from what
prevails at the present day. The problem prestMited l)y
these ancient islands is often complicated by the changes
they themselves have undergone since the period of their
separation. A partial subsidence will liave led t«» tlic
412 ISLAXD LIFE
I'ATiT TI
extinction of some of Iho 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 continent 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 might be produced ; for besides the relics
of the ancient fauna, we might have successi^^e immigra-
tions 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 jDhenomena of distribution presented by
these ancient islands.
Undoubtedly the most interesting of such islands, and
that which exhibits their chief peculiarities in the greatest
perfection, is Madagascar, and we shall therefore enter
somewhat fully into its biological and physical history.
^ Physical Features of Madagascar. — This great island is
situated about 250 miles from the east coast of Africa, and
extends from 12'' to 2o}/ S. Lat. It is almost exactly
1,000 miles long, with an extreme width of 360 and an
average width of more than 260 miles. A lofty granitic
plateau, from eighty to 160 miles wdde and from 3,000 to
5,000 feet high, occupies its central portion, on Avhich rise
peaks and domes of basalt and granite to a height of
nearly ^ 9,000 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 con-
tinuous 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
north-east coming down to the sea-shore.
MADAGASCAR.
The Shaded Fkrt shetvs the Elevated Gram-
■t/c region, the Black dots.the VclcanicdisirictSi
while Dense forests surround C^e Island
414 ISLAND LIFE
The sea around Madagascar, when the shallow bank 'on
which it stands is passed, is generally deep. This 100-
f'athom 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 Mozambi([uo to a distance of about eighty
miles. The Mozambique Channel is rather more than
1,000 fathoms deep, but there is only a narrow belt of this
depth opposite Mozambique, and still narrower where the
Comoro Islands and adjacent shoals seem to form
stepping-stones to the continent of Africa. The 1,000-
fathom line includes Aldabra and the small Farquhar
Islands to the north of Madagascar : while to the east the
sea deepens rapidly to the 1,000-fathom line and then
more slowly, a profound channel of 2,400 fathoms separat-
ino- Madao-ascar 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 IjJOO-fathom line includes them all,
with an area about lialf that of Madagascar itself. A little
farther north is the Seychelles group, also standing on an
extensive 1,000-fathom bank, while all round the sea is
more than 2,000 fathoms deep.
It seems probable, then, that to the north-east of
Madagascar there was once a series of very large islands,
separated from it by not very wide straits ; while east-
ward across the Indian Ocean we find the Chagos and
Maldive coral atolls, perhaps 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 at p. 424, are of
great imjjortance in explaining some anomalous features
in the zoology of this great island.
If the rocks of Secondary age Avhich form a belt around
the island are held to indicate that Madagascar was once
of less extent than it is now (though this by no means
necessarily follows), we have also evidence that it has
recently been considerably larger ; for along the east coast
there is an extensive barrier coral-reef about 350 miles
in lenofth, and varvino- in distance froii] the land from
.J5^^., >,v^.v.. ,^v^^, .^.^
416 ISLAND LIFE paht ii
a quarter of a mile to three or four miles. This seems
to indicate recent subsidence ; while we have no record
of raised coral rocks inland which would certainly mark
any recent elevation, though fringing coral reefs surround
a considerable portion of the northern, eastern, and south-
western 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 Maclaga.scar. — 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, the isolation, or the beauty of its
forms of life. In order to exhibit the full 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.
Mahimalia. — Madagascar possesses no less than sixty-six
species of mammals — a certain proof in itself that the
island has once formed part of a continent ; but the cha-
racter of these animals is very extraordinary and altogether
different from the assemblage now found in Africa or in
any other existing continent. Africa is now most promi-
nently characterised by its monkeys, apes, and baboons;
by its lions, leopards, and hyienas ; by its zebras, rhino-
ceroses, elephants, buffaloes, giraffes, and numerous species
of antelopes. But no one of these animals, nor any thing
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 tapirs, 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
Avhere we must look for their jDrobable 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-organised and very ancient creatures
CHAP. XIX THE MADAGASCAR GROUP 417
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 number 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 lemurs are more nearly allied to those
of Madagascar than are the Asiatic, the whole series
appearing to be the disconnected 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 grouj) distributed over all the
great continents; and five genera of a peculiar family,
Centetidse, which family exists nowhere else on the globe
except in the two largest West Indian Islands, Cuba and
Hayti, thus adding still further to our embarrassment
in seeking for the original home of the Madagascar fauna.
We then come to the Carnivora, wdiich are represented
by a peculiar cat-like animal, Cryptoprocta, forming a
distinct family, and having no close allies in any part of the
globe ; and eight civets belonging to four peculiar genera.
Here we first 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, Eupleres to Suricata and Crossarchus.^
The Rodents consist only of four rats and mice of
peculiar genera, one of which is said to be allied to an
American genus ; and lastly we have a river-hog of the
African genus Potamocha3rus, and a small sub-fossil
hippopotamus, both of which being semi-aquatic animals
might easily have reached the island from Africa, by
way of the Comoros, without any actual land connection.-
Reptiles of Madagascar. — Passing over the birds for
the present, as not so clearly demonstrating land-connec-
1 See Dr. J. E. Gray's "Revision of the ViverridK,"" in Proc. Zool. Soc.
1864, p. 507.
- Some of the Bats of Madagascar and East Africa are said to have_ their
nearest allies in Australia. (See Dobson in Nature, Vol. XXX. p. 575.)
K K
418 ISLAND LIFE part ii
tion, let us see wliat indications arc afforded by the
reptiles. The large and universally distributed family
of Colubrine snakes is represented in Madagascar, not by
African or Asiatic genera, bat by two American genera
— Philodryas and Heterodon, and by Herpetodryas, a
genus found in America and China. The other genera
are all peculiar, and belong mostly to widespread tropical
families; but two families — Lycodontidse and Viperidse,
both abundant in Africa and the Eastern tropics — are
absent. Lizards are mostly represented by peculiar genera
of African or tropical families, but several African genera
are represented by peculiar species, and there are also
some species belonging to two American genera of the
Iguanidse, a family which is exclusively American ; while
a genus of geckoes, inhabiting America and Australia, also
occurs in Madagascar.
Relation of Madagascar to Africa. — These facts taken
all together are certainly very ext^-aordinary, 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 Madagascar. 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 or Pliocene age in France,
Germany, Greece, and North-west India, have demon-
strated the fact that all the great African mammals then
inhabited Europe and temperate Asia. We also know
that a little earlier (in Eocene times) tropical Africa was
cut off from Europe and Asia by a sea stretching from the
Atlantic to the Bay of Bengal, at which time Africa must
have formed a detached island -continent such as Aus-
tralia 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
ciiAr. xrx THE MADAGASCAR GROUP 419
in the latter porti(jii of the Miocene or early in tlie
Pliocene period.^
It is clear, therefore, that if Madagascar had once formed
part of Africa, but had been separated from it before
Africa was united to Europe and Asia, it Avouldnot contain
any of those kinds of animals which then first entered the
country. But, besides the African mammals, we know
that some birds now confined to Africa then inhabited
Europe, and we may therefore fairly assume that all the
more important groups of birds, reptiles, and insects, now
abundant in Africa but absent from Madagascar, formed no
part of the original African fauna, but entered the country
only after it was joined to Europe and Asia.
Early History of Africa and Madarjascar. — We have seen
that Madagascar contains an abundance of mammals, and
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 obtained any mammals at all
i This view was, I believe, first advanced by Professor Huxley in his
** Anniversary Address to the Geological Society," in 1870. He says : — '_' In
fact the Miocene mammalian fauna of Europe and the Himalayan regions
contain, associated together, the types which are at present separately
located in the South African and Indian provinces of Arctoga?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 ]\Iiddleand Upper Eocene
epochs. Hence it becomes highly probable that the well-known similari-
ties, and no less remarkal)le differences, letween the present fauna? of
India and South Africa have arisen in some such fashion as the following :
Some time during the Miocene epoch, the bottom of the numinulitic sea
was upheaved ;!nd converted into dryland in the direction of a line extend-
ing from Abyssinia to the mouth of the Ganges. By this means the
Dekkan on the one hand and South Africa on the other, became connected
with the Miocene dry 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 offered as wide contrasts as the vnlleys of the
Ganges and Arabia do now, many forms which made their way into AlViea
must have been different from those which reached the Dekkan, while
others might pass into both these sub-provinces,"
This question is fully discussed in my GeonrapMcal Distribution of
Animah (Vol. I., p. 285), where I expressed views somewhat different from
those of Professor Huxley, and made some slight errors which are corrected
in the present work. As I did not then refer to Professor Huxley's prior
statement of the theory of Miocene immigration into Africa (which I had
read but the reference to which I could not recall) I am happy to give liis
views here.
!•; i: li
420 ISLAND LIFE part ii
Now these ancient African mammals are Lemurs, Insecti-
vora, and small Carnivora, chiefly Viverridse ; and all these
groups are known to have inhabited Europe in Eocene and
Miocene times ; and that the union was with Europe
rather than with America is clearly proved by the fact that
even the insectivorous Centetidse, now confined to Mada-
gascar and the West Indies, inhabited France in the Lower
Miocene period, while the Viverridse, or civets, which form
so important a part of the fauna of Madagascar as well as
of Africa, were abundant in Europe throughout the whole
Tertiary period, but are not known to have ever lived in
any part of the American continent. We here see the
application of the principle which we have already fully
proved and illustrated (Chapter IV., p. 60), that all ex-
tensive groups have a wide range at the period of their
maximum development ; but as they decay their area of
distribution diminishes or breaks up into detached frag-
ments, which one after another disappear till the group
becomes extinct. Those animal forms which we now find
isolated in Madagascar and other remote portions of the
globe all belong to ancient groups which are in a decaying
or nearly extinct condition, while those which are absent
from it belong to more recent and more highly-developed
types, which range over extensive and continuous areas,
but have had no opportunity of reaching the more ancient
continental islands.
Anomalies of Distribution and How to ExiAain Them. — If
these considerations have any weight, it follows that there
is no reason whatever for supposing any former direct
connection between 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 extended over the great
northern continents. We might as reasonably 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 Peruvian Andes, and another between
Sumatra and Brazil, in order that the ancestral tapir of
one country might have passed over to the other. In both
CHAr. XIX THE MADAGASCAR (JROUT 421
these cases we have ample proof of the former wide
extension of the group. Extinct camels of numeroufi
species abounded in Nortli America in Miocene, Phocene,
and even Post-pliocene times, and one lias also been found
in North-western 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 con-
tinent as a centre the camel tribe spread westward, over
now-submerged land at the shallow Behring Straits and
Kamschatka Sea, into Asia, and southward along the
Andes into South America. Tapirs are even more inter-
esting and instructive. Their remotest known ancestors
appear in Western Europe in the early portion of the
Eocene period ; in the latter Eocene and tlie 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 way again
to North, and thence to South, America, where their
remains are found in caves and gravel deposits. It is an
instructive fact that in the Eastern continent, where they
were once so abundant, they have dwindled down to a
single species, existing in small numbers in the Malay
Peninsula, Sumatra, and Borneo only; while in the
Western continent, where they are comparatively recent
immigrants, they occu2)y a much larger area, and are re-
presented 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 ? Such cases as
these — and there are many others ecpudly striking — show
us with the greatest distinctness how nature has worked
in bringing about the exam])les of anomalous 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 numerous instances of
anomalous distribution we discover among such groups as
reptiles, birds, and insects, whore we rarely have any direct
evidence of their past migrations through the discovery of
422 ISLAND LIFE part ii
fossil remains. Whenever we can trace the past history of
any group of terrestrial animals, we invariably find that
its actual distribution can be explained by migi-ations
effected by means of comparatively slight modifications of
our existing continents. 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 in our fifth chapter, the testimony of geology itself,
if fairly interpreted, upholds the same theory of the stability
of our continents and the j^ermanence of our oceans. Yet
so easy and pleasant is it to speculate on former changes
of land and sea with which to cut the gordian knot offered
by anomalies of distribution, that we still continually meet
with suggestions of former continents stretching in every
direction across the deepest oceans, in order to explain the
presence 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 whose distribution in early geological
periods we generally know little or nothing.
The Birch of Madagascar, as Indicating a Sui^posed
Lemurian Continent. — Having thus shown how the distri-
bution of the land mammalia and reptiles of Madagascar
may be well explained 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 distribution and affinities of the
birds present an insuperable objection to this view, and
require the adoption of a hypothetical continent — Lemuria
— extending from Madagascar to Ceylon and the Malay
Islands.
There are about one hundred and fifty land birds known
from the island of Madagascar, of which a hundred and
twenty-seven are jDeculiar ; and about half of these peculiar
species belong to peculiar genera, many of which are
extremely isolated, so that it is often difficult to class them
in any of the recognised families, or to determine their
affinities to any living birds.^ Among the other moiety,
^ The total iiuinLer of Madagascar birds is 238, of which 129 are
CHAP. XIX THE MADAGASCAR GROUT 4ii:j
belonging to known genera, we find fifteen wliich liave
luicloubted African affinities, while five or six are as
decidedly Oriental, the genera or nearest allied species
being found in India or the Malay Islands. It is on the
presence of these peculiar Indian types that Dr. Hartlaub,
in his recent work on the Birds of Madnfjascar 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, horn-
bills, and bustards — besides a host of peculiar African
genera — as sufficiently disproving the statement in my
GeograpMcal 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 mammals, 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-eaters and the
trogons, for example, — are actually known to have
inhabited Europe along with the large mammalia which
subsequently migrated to Africa. As to the peculiarly
Eastern genera — such as Copsychus and Hypsipetes, with
a Dicrurus, a Ploceus, a Cisticola, and a Scops, all closely
allied to Indian or Malayan species — although very striking
to the ornithologist, they certainly do not outweigh the
fourteen African genera found in Madagascar. Tlieir
presence may, moreover, be accounted for more satisfac-
torily than by means of an ancient Lemurian continent,
which, even if granted, would not explain the very facts
adduced in its support.
Let us first prove this latter statement.
The supposed " Lemuria " must have existed, if at all,
at so remote a period that the higher animals did not then
inhabit either Africa or Southern Asia, and it must liave
;il).solulcly peculiar to tlir island, as arc iliirty-fivo of the i;fiK'ra. All tho
jjoouliar hirds Init two arc land birds. These arc the numbers giveu in M.
Grandidier's ijrcat work on Mada'^ascar.
424 ISLAND LIFE part it
become partially or wholly submerged before they reached
those countries ; otherwise we should find in Madagascar
many other animals besides Lemurs, Insectivora, and
Viverridse, especially such active arboreal creatures as
monkeys and squirrels, such hardy grazers as deer or an-
telopes, or such wide-ranging carnivores as foxes or bears.
This obliges us to date the disaj^pearance of the hypotheti-
cal continent about the earlier part of the Miocene epoch
at 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 presence Dr. Hartlaub upholds the theory of a
Lemuria, are slightly modified forms of existing Indian
genera, or sometimes, as Dr. Hartlaub himself points out,
s2oecies hardly distinguisliahle from those of India. Now all
the evidence at our command leads us to conclude that,
even if these genera and species were in existence in the
early Miocene period, they must have had a widely differ-
ent distribution from what they have now. Along with so
many African and Indian genera of mammals they then
probably inhabited Europe, which at that epoch enjoyed a
sub-tropical climate ; and this is rendered almost certain
by the discovery in the Miocene of France of fossil remains
of trogons 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 introduction into Madagascar, as they could have
followed the same track as the mammalia of Miocene
Europe and Asia ; while if, as I maintain, they are of more
recent date, then Lemuria had ceased to exist, and could
not have been the means of their introduction.
Submerged Islands hetween Madagascar and India. —
Looking at the accompanying map of the Indian Ocean,
we see that between Madagascar and India there are now
extensive shoals and coral reefs, such as are usually held
to indicate subsidence; and we may therefore fairly
postulate the former existence here of several large islands,
some of them not much inferior to Madagascar itself.
These reefs are all separated from each other by very deep
CHAP. XIX
THE MADAGASCAR GROUP
425
sea — much deeper than that which divides Madagascar
from Africa, and we have therefore no reason to imagine
their former union. But they would nevertlieless greatly
facilitate the introduction of Indian birds int<j the Mas-
carene Islands and Madagascar ; and these facilities existing,
such an immigration would be sure to take place, just as
surely as American birds have entered the Galapagos and
Juan Fernandez, as European birds now reach the Azores,
MAT OF Tin: INDIAN OCEAN.
Showing the position of banks less than 1,0()0 fathoms deep between Afriea and the
Indian PeninsiUa.
and as Australian birds reach such a distant island as New
Zealand. This would take place the more certainly because
the Indian Ocean is a region of violent periodical storms
at the changes of the monsoons, and we have seen in tlie
case of the Azores and Bermuda liow important a factor
this is in determining the transport of birds across the
ocean.
426 ISLAND LIFE
The final disappearance of these now sunken islands
does not, in all probability, date back to a very remote
epoch ; and this exactly accords with the fact that some of
the birds, as well as the fruit-bats of the 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 genus
of Indian or Malayan mammals is found in Madagascar,
sufficiently proves that it is no land-connection that has
brought about this small 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 Insectivora, A land-con-
nection with some continent was undoubtedly necessary,
or there would have been no mammalia at all in Mada-
gascar ; and the nature of its fauna on tlie whole, no less
than the moderate depth of the intervening strait and the
comparative approximation of the opposite shores, clearly
indicate that the connection was with Africa.
Concluding licmarks on " Lcmuriar — I have gone into
this question in some detail, because Dr. Hartlaub's
criticism on my views has been reproduced in a scientific
periodical,^ and the supposed Lemurian continent is
constantly referred to by quasi-scientific writers, as well as
by naturalists and geologists, as if its existence had been
demonstrated by facts, or as if it were absolutely necessary
to postulate sucli a land in order to account for the entire
series of plienomena connected with the Madagascar fauna,
and especially with the distribution of the Lemuridae.^ I
1 The Ihis, 1877, p. 334.
2 In a paper read before the Geological Society in 1874, Mr. H. F. Blan-
ford, from the similarity 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 liis satisfaction with
' ' this further evidence derived from the fossil flora of the Mesozoic series of
India in corroboration of the former existence of an old submerged conti-
nent— 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 frag-
inentary evidence derived from such remote periods (even if there were no
evidence on the other side) as indicating geographical changes. Tlie notion
citAP. XIX THE MADAGASCAR GROUP 427
think I have now sliown, on the other liand, that it was
essentially a provisional hypothesis, very useful in callin<;-
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 presented by the Atlantic Islands and
the relations of the European and North American flora
and fauna. The Atlantis is now rarely introduced seriously
except by the absolutely unscientific, having received its
death-blow by the chapter on Oceanic Islands in the Orirjin
of S'pccics, and the researches of Professor Asa Gray on the
affinities of the North American and Asiatic floras. But
" Lemuria " still keeps its place — a good example of the
survival of a provisional hypothesis which offers wliat seems
an easy solution of a difficult problem, and has received an
appropriate and easily remembered name, long after it has
been proved to be untenable.
It is now more than fifteen years since I first showed, by
a careful examination of all the facts to be accounted for,
that the hypothesis of a Lemurian continent was alike
unnecessary to explain one portion of the facts, and
inadequate to explain the remaining 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 hand have those who have hitherto supported the
hypothesis taken any opportunity of acknowledging its
weakness and inutility. I have therefore here explained
my reasoms for rejecting it somewhat more fully and in a
more popular form, in the hope that a check may thus be
placed on the continued re-statement of this unsound
theory as if it were one of the accepted conclusions of
modern science.
that a similaiity in the piodiietions of widely separated eo)itinent.s at any
past epoch is only to he explained hy the existence of a dira't hind-con-
nection, is entirely opposed to all that we know of the wide and varyin<,'
distrihution of ('7/ ty])es at dilferent peiiods, as well as to the jL,'reat i)0wcrs
of dispersal over moderate widths of ocean possessed hy all animals exce)»t
mammalia. It is no less opposed to what is now known of the general
permanency of the great continental and oceanic areas ; while in this par-
ticular case it is totally inconsistent (as has heen shown ahove) with the
actual facts of the distrihution of animals.
^ Gcograj^hical Distribution of AnunaJs, VoL I., pp. 27ii — W2.
428 ISLAND LIFE part ii
The Mascarene Islands} — In the Geographical Distri-
hution 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 peculiari-
ties, and with it form the Malagasy sub-region of the
Ethiopian region. As no great additions have since been
made to our knowledge of the fauna of these islands, and
my object in this volume being more especially to
illustrate the mode of solving distributional problems by
means of the most suitable examples, I shall now confine
myself to pointing out how far the facts presented by these
outlying islands support the views already enunciated with
regard to the origin of the Madagascar fauna.
The Comoro Islands. — This group of islands is situated
nearly midway between the northern extremity of
Madagascar and the coast of Africa. The four chief
islands vary between sixteen and forty miles in length, the
largest being 180 miles from the coast of Africa, while one
or two smaller islets are less than 100 miles from
Madagascar. All are volcanic. Great Comoro being an
active volcano 8,500 feet high ; and, as already stated, they
are situated on a submarine bank with less than 500
fathoms soundings, connecting Madagascar with Africa.
There is reason to believe, however, that these islands are
of comparatively recent origin, and that the bank has been
formed by matter ejected by the volcanoes or by upheaval.
Anyhow, there is no indication whatever of there having
been here a land-connection between Madagascar and
Africa; while the islands themselves have been mainly
colonised from Madagascar, some of them making a near ap-
proach to the 100-fathom bank which surrounds that island.
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 comorensis), a group which ranges from
Australia to Asia and Madagascar but is unknown in
Africa. Of land-birds forty-one species are known, of
^ The term ' ' ]\Iascarene " is used here in an extended sense, to include
all the islands near ]\Iadagascar which resemble it in their animal and
vegetable productions.
cuw. XIX THE lAIADAGASCAR GROUP 429
which sixteen are peculiar to the islands, twenty-one arc
found also in Madagascar, and three found in Africa and
not in Madagascar; while of the peculiar species, six
helong to Madagascar or Mascarene genera. A species of
Chameleon is also peculiar to the islands.
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 indicated by the extensive
shallow bank at its northern extremity, so as to allow of
the easy passage of birds, and the occasional transmission
of small mammalia by means of floating trees.^
The Seychelles Arehiioelago. — Tliis interesting group
consists of about thirty small islands situated 7U0 miles
N.N.E. of Madagascar, or almost exactly in the line formed
by continuing the central 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 gi'anite, with
mountains rising to 3,000 feet in Mahe, and to from 1,000
to 2,000 feet in several of the other islands. We can
therefore hardly doubt that they form a portion of the
gTeat line of upheaval which produced the central granitic
mass of Madagascar, intervening points being indicated by
the Amirantes, the Providence, and the Farquhar Islands,
which, though all coralline, probably rest on a gTanitic
basis. Deep channels of more than 1,000 fathoms now
separate these islands from each other, and if they were
ever sufficiently elevated to be united, it was probably at a
very remote epoch.
The Seychelles may thus have had ample facilities for
receiving from Madagascar such immigrants as can pass
over narrow seas ; and, on the other hand, they were
equally favourably situated as regards the extensive Saya
de Malha and Cargados banks, which were probably once
^ For the birds of the Comoro Islands see Proc. Zooh Sor., 1877, [k 295,
and 1879, p. 673.
430 ISLAND LIFE part ii
large islands, and may have supported a ricli insular flora
and fauna of mixed Mascarene and Indian type. The
existing fauna and flora of the Seychelles must therefore
be looked upon as the remnants which have survived the
partial submergence of a very extensive island ; and the
entire absence of non-aerial 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 extinction of such
mammals as may once have inhabited it. The birds and
reptiles, however, though few in number, are very
interesting, and throw some further light on the past
history of the Seychelles.
Birds of the Seychelles. — Fifteen indigenous land-birds
are known to inhabit the group, thirteen of which are
peculiar species,^ belonging to genera which occur also in
Madagascar or Africa. The genera which are more
peculiarly Indian are, — Copsychus and Hypsipetes, also
found in Madagascar ; and Palaeornis, which has species in
Mauritius and Rodriguez, as well as one on the continent
of Africa. A black parrot (Coracopsis), congeneric with
two species that inhabit Madagascar and with one that is
peculiar to the Comoros ; and a beautiful red-headed blue
pigeon (Alecforcenas i^ulcherrimus) allied to those of Mada-
gascar and Mauritius, but very distinct, are the most
remarkable species characteristic of this group of islands.
Beptiles and Amjyhihia of the Seyehelles. — The reptiles
and amphibia are rather numerous and very interesting,
indicating clearly that the islands can hardly be classed as
oceanic. There are seven species of lizards, three being
peculiar to the islands, while the others have rather a
wide ranofe. The first is a chameleon — defenceless slow-
^ The following is a list of these peculiar birds. (See the Ibis, for 1867,
p. 359 ; and 1879, p. 97.)
Passeres. Psittaci.
ElUsia seyehellensis. Coracopsis barklyi.
Copsychus seychellaru m . Palceorms wardi.
Hypsipetes crassirostris. Columb.^.
Tchitrea corvina. Alectormnas pulcherrimns
Nectarinia dussumieri. Turtur rostratus.
Zosteropsmodesta. AcciPiTRES.
,, semiflava.
Foudia seychellariim. Tinnunculus gracilis.
CHAP. XIX THE ^lADAGASCAR GROUP 431
moving lizards, especially abuiulant in Madagasrar, from
which no less tlian eighteen species are now known,
about the same number as on the continent of Africa.
The Seychelles species {Chamcvleon tigris) also occurs at
Zanzibar. The next are skinks (Scincidoe), small ground-
lizards with a wide distribution in the Eastern hemi-
sphere. Two species are however peculiar to the islands
— Malmict scychcJlcnsis and M. UTightii. The otlicr
peculiar species is one of the geckoes (Geckotidte) named
JEluronyx seycliellensis, and theie are also three other
geckoes, Phehuma madagascarensis, Gehyra mntilata and
Heinidadylus frenaUis, the two latter having a wide
distribution in the tropical regions of both hemispheres.
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 family have a
very wide range they have been assisted in their migrations
by man, though their habit of clinging to trees also renders
them likely to be floated with large pieces of timber to
considerable distances. Dr. Percival Wright, to whom I
am indebted for much information on the productions
of the Seychelles Archipelago, informs me that the last-
named species varies greatly in colour 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 colour
from those of the mainland, usually becoming rich blue or
black (see Nature, Vol. XIX. p. 97) ; and we thus learn
how readily in some cases differences of colour are brought
about, either directly or indirectly, by local conditions.
Snakes, as is usually the case in small or remote islands,
are far less numerous than lizards, only two species being
known. One, Dromicus scyclicllensis, is a peculiar species
of the family Colubridoe, the rest of the genus being found
in Madagascar and South America. The other, Boodon
gcometricus, one of the Lycodontid;r, or fangetl ground-
snakes, is also peculiar. So far, then, as the re2:)tiles are
432 ISLAND LIFE part ii ™
concerned, there is nothing but 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
in the Seychelles by two tailless and two serpent-like
forms. The frogs are Bana mascarenicnsis, found also in
Mauritius, Bourbon, Angola, and Abyssinia, and probably
all over tropical Africa ; and Mcgalixalus seycliellcnsis a
peculiar tree-frog having allies in Madagascar and tropical
Africa. It is found, Dr. Wright informs me, on the
Pandani or screw-pines ; and as these form a very
characteristic portion of the vegetation of the Mascarene
Islands, all the species being peculiar and confined each to
a single island or small group, we may perhaps consider it
as a relic of the indigenous fauna of that more extensive
land of which the present islands are the remains.
The serpentine Amphibia are represented by two species
of Csecilia. These creatures externally resemble large
worms, except that they have a true head with jaws and
rudimentary eyes, while internally they have of course a
true vertebrate skeleton. They live underground, burrow-
ing by means of the ring-like folds of the skin which
simulate the jointed segments of a worm's body, and when
caught they exude a viscid slime. The young have
external gills which are afterwards rejDlaced by true lungs,
and this peculiar metamorphosis shows that they belong to
the amphibia rather than to the reptiles. The Csecilias
are widely but very sparingly distributed through all the
tropical regions ; a fact which may, as we have seen, be
taken as an indication of the great antiquity of the group,
and that it is now verging towards extinction. In the
Seychelles Islands there appear to be three species of these
singular animals. CryptoiJSoioMs muliiijlicatus is confined
to the islands; Hcrpele squalostoma is found also in
Western India and in Africa ; while Hypogcophis rostratus
inhabits both West Africa and South America.^ This
last is certainly one of the most remarkable cases of
the wide and discontinuous distribution of a species ; and
^ Specimens are recorded from West Africa in the Proceedings of the
Academy of Natural Science, Philadelphia, 1857, p. 72, while specimens
GiiAP. xjx THE MADAGASCAR GROUP 438
when we consider the habits of life of these animals and
the extreme slowness with which it is likely tliey can
migrate into new areas, we can hardly arrive at any other
conclusion 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 Avere, in these three remote
portions of the globe. The extreme stability and long
persistence of specific form which this implies is extra-
ordinary, but not unprecedented, among the lower verte-
brates. The crocodiles of the Eocene period differ but
slightly from those of the present day, while a small fresh-
water turtle from the Pliocene deposits of the Siwalik
Hills is absolutely identical with a still living Indian
species, Emys tcdus. The mud-fish of Australia, Ceratochts
foTsteri is a very ancient type, and may well have remained
specifically unchanged since early Tertiary times. It is
not, therefore, incredible that this Seychelles Caicilia 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 con-
tinents allowed of the migration of such types over the
whole northern hemisphere, from which they subsequently
passed into the southern hemisphere, maintaining them-
selves only in certain limited areas, where the physical
conditions were especially favourable, or where they were
saved from the attacks of enemies or the competition of
higher forms.
Fresli-vxttcr Fishes. — The only other vertebrates in the
Seychelles are two fresh-water fishes abounding in the
streams and rivulets. One, Hcqjlochilus p/«?//(X2>/t is
peculiar to the islands, but there are allied species in
Madagascar. It is a pretty little fish about four inches
long, of an olive colour, with rows of red spots, and is very
abundant in some of the mountain streams. The fishes of
this genus, as I am informed by Dr. Glinther, often inliabit
l)otli sea and fresh water, so that their migration from
ill tlio Paris Muscuui were ]>rouglit l»y D'Orbigiiy from S. America. Dr.
\N'rif;ht".s spocimons from the Seychelles have, as he informs me, hoeii
determined to be the same species l)y Dr. Peters of licrlin.
F F
434 ISLAND LIFE
Madagascar to the Seychelles and subsequent modification,
ofifers no difficulty. The other species is Funduhts
orthonotus, found also on the east coast of Africa ; and as
both belong to the same family — Cyprinodontidae — this
may possibly have migrated in a similar manner.
Land-shells. — The only other group of animals inhabiting
the Seychelles which we know with any approach to
completeness, are the land and fresh-water moll u sea, 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 destruction of so much of the forests which once
covered the islands. Seven of the species — and among
them one of the most conspicuous, Acliatina fidicct — have
almost certainly been introduced ; and the remainder show
a mixture of Madagascar and Indian forms, with a prepon-
derance of the latter. Five genera — Streptaxis, Cyatho-
ponea, Onchidium, Helicina and Paludomus, are mentioned
as being especially Indian, Avhile only two — Tropidophora
and Gibbus, are found in Madagascar but not in India.^
About two-thirds of the species appear to be peculiar to
the islands.
Mauritius, Bourhon and Rodriguez. — 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. Yet their productions
are so closely related to those of Madagascar, to which they
may be considered as attendant satellites, that it is
absolutely necessary to associate them together if we wish
to comprehend and explain their many interesting
features.
Mauritius and Bourbon are lofty volcanic islands,
evidently of great antiquity. They are about 100 miles
apart, and the sea between them is less than 1,000 fathoms
deep, while on each side it sinks rapidly to depths of 2,400
and 2,600 fathoms. We have therefore no reason to
believe that they have ever been connected with Mada-
^ "Additional Notes on the Land-sliells of the Seychelles Islands." By
Geoffrey Nevill, C.M.Z.S. Proc. ZooJ. Soc. 1869, p/61.
CHAP. XIX THE MADAGASCAR GROUP 436
gascar, and this view is strongly supported Ly the character
of their indigenous fauna. Of this, however, we have not
a very complete or accurate knowledge, for though both
islands have long been occupied by Europeans, the study
of their natural products was for a long time greatly
neglected, and owing to the rapid spread of sugar cultiva-
tion, the 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 island, Rodriguez, is also
volcanic ; but it has, besides a good deal of coralline rock,
an indication of partial submergence 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
^ In Miiilhird's JS'oics sar Vide dc Ileuiuon, a consideniljle number of
iiianimalia are given as "wihl," such as Loaicr viougoz and Ccatctcssctosus^
l)oth Madagascar species, Avitli sueli undoubtedly introduced animals as a
wild cat, a hare, and several rats and mice. He also gives two .species of
frogs, seven lizards, and two snakes. The latter are both Indian species
ajid certainly imported, as are most probably the frogs. Legouat, who
resided some years in the island nearly two centuries ago, and who was
a closer observer of nature, mentions numerous birds, large bats, land-
tortoises, and lizards, but no other reptiles or venomous animals except
scorpions. AVe 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 .species, some peculiar to the island,
others common to Africa and the other JMascarene Islands. The following
list by Prof Dumeril is given in ]\Iaillard's work : —
Platydactylus cepedianus. Hemidactylusj'ienatus.
,, ocellatus. Gongylus bojtrii.
Hemidactylus pcronii. Abhpltarus peronii.
.. vudilatus.
Four species of chameleon arc now recorded from Bourljon iiml one from
i\Iauritius (J. Keay Greene, ]\[.D., in Pop. Science Ilcv. April, 18S0), but
as they are not mentioned by the old writers, it is pretty certain tliat these
creatures are recent introductions, and this is the more probabh- as they
are favourite domestic pets.
Darwin informed me that in a work entitled Voihkjc a V hh tic France,
■jiar un ({(Jicicr dulloi, ])ublished in 1770, it is stated that a fre.sh-water fish
had been introduced from Batavia and. had multiplied. 'I'he writer also
siiys (p. 170): " 071 cc essaije, Diais sans mcces. d'y (r(msj.>i>r/er dcs (/renouillcs
</itl manrjciU Ics ouifs rjue h's vioiistigues drposcnl s^ir hs cnu.r s(ag7iantcs."
It thus fip[)ears that there were then no frogs on the island.
F F :i
436 ]SLA^^D LIFE
sea rapidly deepens to more than 2,000 fathoms, so that it
is truly oceanic like its larger sister isles.
Birds. — The living birds of these islands are few in
number and consist mainly of peculiar species of Mascarene
types, together with two peculiar genera — Oxynotus
belonging to the Campephagidge or caterpillar-catchers, a
family abundant in the old-world tropics ; and a dove,
Trocazza, forming a peculiar sub-genus. The origin of
these birds offers no difficulty, looking at the position of the
islands and of the surrounding shoals and islets.
Extinct Birds. — These three islands are, however, pre-
eminently remarkable as having been the home of a group
of large ground-birds, quite incapable of flight, and
altogether unlike anything found elscAvhere on the globe ;
and which, though once very abundant, have become
totally extinct within the last two hundred years. The
best known of these birds is the dodo, which inhabited
Mauritius ; while allied species certainly lived in Bourbon
and Rodriguez, abundant remains of the species of the
latter island — the "solitaire," having been discovered,
corresponding with the figure and description given
of it by Legouat, who resKled in Rodriguez in 1692.
These birds constitute a distinct family, Didid^, allied to
the pigeons but very isolated. They Avere quite defenceless,
and were rapidly exterminated when man introduced dogs,
pigs, and cats into the island, and himself sought them for
food. The fact that such perfectly unprotected creatures
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 Avhatever,
is itself almost demonstrative that Mauritius, Bourbon, and
Rodriguez are very ancient but truly oceanic islands.
From Avhat we know of the general similarity of Miocene
birds to living genera and families, 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 ances-
tral ground-feeding pigeon of large size to have reached
the group by means of intervening islands afterwards
submerged, and to have thenceforth remained to increase
and multiply unchecked by the attacks of any more power-
fiiAi'. XIX THE MADAGASCAR GROUP 437
fill animals, wo can well understand that the wings, beino-
useless, would in time become almost aborted.^ It is also
not improbable that this process would be aided by
natural selection, because the use of wings niiglit be
absolutely prejudicial to the birds in their new home.
Those that flew up into trees to roost, or tried to cross
over the mouths 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 tlie more bulky and short-winged
individuals, who took to sleeping on the ground in the forest,
would be preserved from such dangers, and perhaps also from
the attacks of birds of prey which may always have visited
the islands. But whether or no this was the mode by which
these singular birds acquired their actual form and
structure, it is perfectly certain that their existence and
development depended on com23lete isolation and on free-
dom 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 Zealand, 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 w^e may therefore be sure that
^ That the dodo is really an abortion from a more perfect type, and not a
direct development from some lower form of Avingless bird, is shown by its
possessing a keeled sternnm, thongli the keel is exceedingly reduced, being
only three-quarters of an indi deep in a length of seven inches. The most
terrestrial pigeon — the Didunculus of the Samoan Islands, has a far (lee])er
and better developed keel, showing that in tlie case of the dodo tlie degrada-
tion has been extreme. We have also analogous examples in otlier extinct
birds of the same group of islands, such as the flightless Rails — Aphanap-
teryx of Mauritius and Erythromachus of Rodriguez, as well as the
large parrot — Lophopsittaeus of Mauritius, and the Xight Heron,
Nydicorax mcgacepluda of Rodriguez, the last two birds probably having
been able to fly a little. The commencement of the same process is to be
seen in the ])eculiar dove of the Se3'chcl]cs, Turlur ovshrihts, wliich, as
Mr. Edward Xewton has shown, has mueli shorter wings tlian its close
ally, T. pictumtus, of jMadagascar. For a full and interesting account of
these and other recently extinct birds see Professor Newton's article on
'•Fossil Birds" in the 'Encvclojncd'ui Brifannim, ninth edition, vol. iii.,
p. 732 ; and that on "The Extinct Birds of Rodriguez," by Dr. A. Giinther
and j\Ir. E. !N'e\\i:on, in the Royal Society's volume on the Transit of Venus
Expedition.
438 ISLAND LIFE part ii
these islands have never formed part of a continent
during any portion of the time when the dodos inhabited
them.
It is a remarkable thing that an ornithologist of Dr.
Hartlaub's reputation, looking at the subject from a purely
ornithological point of view, should yet entirely ignore the
evidence of these wonderful and unique birds against his
own theory, when he so confidently characterises Lemuria
as " that sunken land, which, containing parts of Africa,
must have extended far eastward over Southern India and
Ceylon, and the highest jDoints of which we recognise in
the volcanic peaks of Bourbon and Mauritius, and in the
central range of Madagascar itself — the last resorts of the
mostly extinct Lemurine race which formerly peopled it."^
It is here implied that lemurs formerly inhabited Bourbon
and Mauritius, but of this there is not a particle of
evidence, and we feel pretty sure that had they done so
the dodos would never have been developed there. In
Madagascar there are no traces of dodos, while there are
remains of extinct gigantic struthious birds of the genus
^pyornis, which were no doubt as well able to protect
themselves against the smaller carnivora as are the
ostriches, emus, and cassowaries in their respective
countries at the present day.
The whole of the evidence at our command, therefore,
tends to establish in a very complete manner the " oceanic "
character of the three islands — Mauritius, Bourbon, and
Rodriguez, and that they have never formed part of
"Lemuria" or of any continent.
Reptiles. — Mauritius, like Bourbon, has lizards, some of
which are j)eculiar species ; but no snakes, and no frogs or
toads but such as have been introduced.^ Strange to say,
however, a small islet called Round Island, only about a
mile across, and situated about fourteen miles north-east
of Mauritius, possesses a snake which is not only unknown
in Mauritius, but also in any other part of the world, being
1 See Ihis, 1877, p. 334.
^ A common Indian and Malayan toad {Bufo melanostictus) has been
introduced into Mauritius and also some European toads, as I am informed
by Dr. Gtinther.
CHAP. XIX THE MADAGASCAR GROUP 439
altogether confined to tliis minute islet ! It belongs to
the boa family, and forms a peculiar and very distinct
genus, Casaria, whose nearest allies seem to be the Ungalia
of Cuba and Bolyeria of Australia. It is hardly possible
to believe that this serpent has very long maintained
itself on so small an island ; and though we have no record
of its existence on Mauritius, it may very well have
inhabited the lowland forests without being met with by
the early settlers; and the introduction of swine, which
soon ran wild and effected the final destruction of the
dodo, may also have been fatal to this snake. It is, how-
ever, now almost certainly confined to the one small islet,
and is probably the land-vertebrate of most restricted
distribution on the globe.
On the same island there is a small lizard, Scelotes
hojeri, recorded also from Mauritius and Bourbon, though
it appears to be rare in both islands ; but a gecko, Fhelsuma
guenthcri, is restricted to the island. As Round Island is
connected with Mauritius by a bank under a hundred
fathoms below the surface, it lia^ probably been once
joined to it, and when first seimrated would have been
both much larger and much nearer the main island,
circumstances which would greatly facilitate the trans-
mission of these reptiles to their present dwelling-place,
where they have been able to maintain themselves owing
to the complete absence of competition, while some of them
have become extinct in the larger island.
Flora of Madagascar and the Mascarcnc Islands. — The
botany 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 bo no
doubt of its extreme richness and grandeur, its remark-
able speciality, and its anomalous external relations. It
is characterised by a great abundance of forest-trees and
shrubs 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 affinities the latter preponderates. But there
are also, as in the animal world, some decided South
440 ISLAND LIFE part n
American relations, while other groups point to Australia,
or are altogether isolated.
No less than 3,740 flowering j^lants are now knowaa from
Madagascar with 860 ferns and fern-allies. The most
abundant natural orders are the following :
Species. Species.
Leguminospe 346 Cyperacepe 160
Ferns 318 Rubiacefe 147
Compositpe 281 Acanthaceai 131
Eiiphorbiaceae 228 Gramineai 130
Orchidese 170
The flora contains representatives of 144 natural orders
and 970 genera, one of the former and 148 of the latter
being i3eculiar to the island. The peculiar order,
Chfelnacege, comprises seven genera and twenty-four
species ; while Rubiacese and Composita3 have the largest
number of peculiar genera, followed by Leguminosse and
Melastomacese. Nearly three-fourths of the species are
endemic.
Beautiful flowers are not conspicuous in the flora of
Madagascar, though it contains several magnificent
flow^ering plants. A shrub with the dreadful name
Harimgo^liytmn GrandicUcri has bunches of gorgeous
red flowers ; Tristellateia madagascariensis is a climbing
plant with spikes of rich yellow flowers ; while Poinciana
rcgia, a tall tree, Ehodolccna altivola and AstraiJcea
Wallichii, shrubs, are among the most magnificent
flowering plants in the world. Disa Buchcnaxiana, Com-
melina madagascarica, and TacJiiadenus i^lcdypUru^ are
fine blue-flowered plants, while the superb orchid Angrce-
cum sesquipedcde, Vinca rosm, Eu^phorhia splendens,
and Steiohanctis florihunda^ have been long cultivated
in our hot-houses. There are also many handsome
Combretacea^, Rubiace^e, and Leguminosse ; but, as in most
tropical regions, this wealth of floral beauty has to be
searched for, and produces little effect in the landscape.
The affinities of the Madagascar flora are to a great
extent in accordance with those of the fauna. The
tropical portion of the flora agrees closely with that of
tropical Africa, while the plants of the highlands are
riiAP. XIX THE MADAGASCATl GROUP 441
oqnally allied to those of the Cape and of tlie mountains
of Central Africa. Some Asiatic types are ])rescnt wliicli
do not occur in Africa; and even the curious Anxrican
affinities of some of tlie animals are reproduced in the
vegetable kingdom. These last are so interesting that
they deserve t(^ be enumerated. An American genus of
Euphorbiacea', Omphalea, has one species in IMadagascar,
and Pedilanthus, another genus of the same natural order,
has a similar distribution. Myrosma, an American genus
of Scitamineoe has one Madagascar species ; while the
celebrated '* travellers' tree," Ravcncda maclagascaricnsis,
belonging to the order Musacea3, has its nearest ally in a
plant inhabiting N. Brazil and Guiana. Echinolrena, a
uenus of orasses, has the same distribution.^
Of the flora of the smaller Madagascarian islands we
possess a fuller account, owing to the recent publication
of Mr. Baker's Flora of the Mcmritius and the Seychelles,
including also Bodriguez. The total number of species
in this flora is 1,058, more than half of which (.5')(]) are
exclusively Mascarene — that is, found only in some of
the islands of the Madagascar group, while nearly a third
(304) are endemic or confined to single islands. Of the
widespread plants sixty-six are found in Africa but not
in Asia, and eighty-six in Asia but not in Africa, showing
a similar Asiatic preponderance to what is said to occur
in Madagascar. With the genera, however, the propor-
tions arc different, for I find by going through the whole
of the generic distributions as given by Mr. Baker, that
out of the 440 genera of wild plants fifty are endemic,
twenty-two are Asiatic but not African, while twenty-eight
are African but not Asiatic. This implies that the more
ancient connection has been on the side of Africa, while
a more recent immigration, shown by identity of species,
has come from the side of Asia ; and it is already certain
that when the flora of Madagascar is more thoroughly
worked out, a still greater African preponderance will be
found in that island.
^ This brief account of the Mada.£fascai' flora has been taken from a very
interesting paper by the Rev. Richard Baron, F.L.S., F.G.S., in the
Journal of the Liiincan S'ocieii/, \o]. XXV., p. 2-1 G ; wliere niudi informa-
tion is given on the distribution of the flora within tlie island.
442 ISLAND LIFE
A few Mascarene genera are found elsewhere only in
South America, Australia, or Polynesia ; and there are
also a considerable number of genera whose metropolis is
South America, but which are represented by one or more
species in Madagascar, and by a single often widely
distributed sjoecies in Africa. This fact throws light upon
the problem offered by those mammals, reptiles, and
insects of Madagascar which now have their only allies in
South America, since the two cases would be exactly
parallel were the African plants to become extinct.
Plants, however, are undoubtedly more long-lived speci-
fically than animals — especially the more highly organised
groups, and are less liable to comj)lete 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
only allies in such distant regions as America and Aus-
tralia, Avhile such cases are 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 remote island of St. Helena.
Mathurina, a genus of Turneraceae, consisting of a single
species peculiar to Rodriguez, has its nearest ally in
another monotypic genus, Erblichia, confined to Central
America. Siegesbeckia, one of the Compositse, consists
of two species, one inhabiting the Mascarene islands, the
other Peru. Labourdonasia, a genus of Sapotaceae, 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 Lauraceae, 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 Seychelles Islands,
CHAP. XIX THE MADAGASCAR GROUP 443
and in Madagascar, Milla, a large genus of Liliaccjc, is
exchisively American, except one species found in Mauri-
tius and Bourbon. Agauria, a genus of Ericaceaj, is
found in ^Madagascar, the Mascarene islands, the plateau
of Central Africa, and the Camaroon Mountains in West
Africa. An acacia, found in Mauritius and Bourbon (A,
heteropliylla), can hardly be separated specifically from
Acacia I'oa 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 anom-
alies 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 anomalies
have, in all probability, been brought about, rendering
quite unnecessary any other changes in the distribution
of sea and land tliau physical and geological evidence
warrants.^
^ It may be interesting to botanists and to students of geographical
distribution to give here an enumeration of the endemic genera of the Flora
of the Mauritim and the. S'eychdle.% as they are nowliero separately tabulated
in that work.
Aphlola (Bixacese) 1 sp.. a shrub, Maur., Rod., Si-v., also Madagascar.
Mediisag>iie (Ternslrdmiaocii ) ...i sp., a shrub, Seychelles.
Astiria (Sterculiace;e) 1 sji., a shrub, Mauritius.
Quivisia (Meliaceai) •'' ^p-, shrubs, Mauritius (-2 sp.), Rodriguez (1 sj'.),
also Bourbon.
rossignya (Sapindaocie) 1 sp., a shrub, Mauritius, aLso Bourbon.
Hornea ., 1 sp., a shrub, Mauritius.
IStadtmanuia ., 1 sp., a shrub, l^Iauritius.
Doratoxylon ,, 1 sp.. a shrub, Mauritius and Bourbon.
<!agnebina (LeguniinosaO 1 sp., a shrub, Mauritius, ahso Madagascar.
Roussea (Saxifragacea-) 1 sp., a climbing shrub, Mauritius and IJourbon.
Tetrataxis (Lythracete) 1 sp., a shrub, Mauritius.
I'siloxylon ,, 1 sp., a shrub, Mauritius and Bourbon.
Mathurina (Turneraccje) 1 sp., a .shrub, Rodriguez.
Fci.'tidia (Myrtacere) 1 sp.. a tree, Mauritius.
l)auais(Rubiace«) 4 sj.., climbing shrubs, Maur. (1 sp.), Ro.lr. (1 sp.).
also Bourbon and Madagasc^ar.
Fernelia (Rubiacea-) 1 sji., a shrub, Mauritius and Rodriguez.
Pyrostria ,, (3 sji., shrubs, Mauritius (.S s]i.), also Bourbon and
Madagascar.
Scj-phochlamys (Rubiacea) 1 sj)., a .shrub, Rodriguez.
Myonima ,, 3 s]!., shrubs, Mauritius, also Bourbon.
Cylindrocline (Coniposit;e) 1 sp., a shrub, Mauritius.
Monarrhenus ,, 'j sji., shrults, Mauritius, also Bourbon and ^rada-
gascar.
444 ISLAND LIFE
PAET 11
Fragmentary Character of the Mascarenc Flora. —
Although the peculiar character and affinities of the
vegetation of these islands is 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 lowlands, 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 inevit-
ably 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
Faujasia (CoinpositaO ?, s],., shrubs, Mauritius, also Bourbon and Mada-
gascai-.
Heterochiienia (Campanulaceo-) 1 s]).. a shrub, Mauritius, also Bourbon.
lamilepis (AsclepiadaceaO 1 sj)., a climber, Rodriguez.
IJecanema ,, \ sj)., a climber, Mauritius, also Madaga.scar.
.Nicodemia (Loganiaceae) 2 sp., shrubs, Mauritius (1 sp.), also Comoro Islands
^ , ,^ and Madagascar.
Bryodes (Scrophulariacea') 1 .sp., herb, Mauritius.
Radamtea ,, o sp., herb, Seychelles (1 .sp.), and Madagascar.
t olea (Bignoniacef.:") 10 .sp., Mauritius (1 .sp.), Seychelles (1 .sp.), also
Bourbon and Madagascai-. (Shrubs, trees, or
climbers.)
Obetia (Urticacea-) 2 sp., .shrubs, Mauritius, Seychelles, and Mada-
gascar.
Bo.squiea (Morese) .3 .sp., trees, Seychelles (1 .sp.), also Madagascar.
Mommia (Monimiaceie) 3sp., trees, Mauritius (2 .sp.), also Bourbon.
Cynorchis (Orchiderp) .3.sp., herb, ter., Mauritius.
Amphorchis ,, i sp., herb, ter., Mauritius, al-so Bourbon.
Arnottia ., 2 sp., herb, ter., Mauritius, also Bourbon.
Aplostellis ,, 1 sp., herb, ter., Mauritius.
Crj'ptopus ,, 1 sp., herb. Epiphyte, Mauritiu.s, al.so^Bom-bon and
ISIadagascar.
Lomatophyllum (Liliacea-) .3 sp., shrubs (succulent), Mauritius, also Bourbon.
Lodoicea (Palma?) 1 .sp., tree, Seyrhelle.s.
Latania .^ 3 j,p_^ trees,' Mauritius (2 sp.), Rodriguez, also
Bourbon.
Hyophorbe , 3 .sp., trees, Maimtius (2 .sp.), Rodriguez, also
Bourbon.
Dictyosperma ,, 1 .sp., tree, Mauritius, Rodriguez, also Bourbon.
Acanthophajnix ., 2 .sp., trees, Mauritius, also Bourbon.
Deckenia , 1 sp., tree, Seychelles.
Xephrosperma ,, 1 .sp., tree, Seychelles.
Roscheria ., 1 .sp., tree, Seychelle.s.
Verschaffeltia , 1 .sp., tree, Seychelles.
Steyensonia ,, 1 sp., tree, Seyehelle.s.
Ochropteris (Filice.s) 1 sjt., herb, Mauritius, also Bourbon and Madagascar.
Among tlie curious features in this list are the gi'eat number of endemic
.shrubs in ]Mauritius, and tlie remarkable assemblage of live endemic genera
of palms in the Seychelles Island.s, AVe ma}^ also notice that one palm
{Latania locldigesii) is confined to Round Island and two other adjacent
islets offering a .singular analogy to the peculiar snake also found there.
CHAP. XIX THE MADAGASCAR GROUl' 445
species. In the Seychelles, too, the indigenous flora lias
])een almost entirely destroyed in most of the islands,
althoiigli the peculiar palms, from tlieir longevity and
comparative hardiness, have survived. Mr. Geoffrey Nevill
tells us, that at Malie, and most of the other islands visited
by him, it was only in a few spots near the summits of the
hills that he could perceive any remains of the ancient
flora. Pinc-ap23les, cinnamon, bamboos, and other plants
have obtained a firm footing, covering large tracts of
country and killing the more delicate native flowers and
ferns. The pine-apple, especially, grows almost to the tops
of the mountains. Where the timber and shrubs have
been destroyed, the water falling on the surface im-
mediately cuts channels, runs off rapidly, and causes the
land to become dr}^ 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 ^ifrica. — In
my Geographical Distribution of Animals 1 have remarked
on the relation between the insects of Madagascar and
those of south temperate Africa, and have speculated on a
great southern extension of the continent at the time when
Madagascar was united with it. As supporting this view
I now quote Mr. Bentham's remarks on the Composita*.
He says: "The connections of the Mascarene endemic
Composita^ especially those of Madagascar itself, arc
eminently with the southern and sub-tropical African
races; the more tropical races, Plucheinea^ &c., may be
rather more of an Asiatic type." He further says that the
(Composite flora is almost as strictl}^ endemic as that of
the Sandwich Islands, and that it is much diversilied, with
evidences of great antiquity, while it shows insular cliar-
acteristics in tlie tendency to tall shrubby or arborescent
forms in several of the endemic or prevailing genera.
Preponderance of Ferns in. the Mascarene Flora. — A
striking character of the flora of these smaller Mascarene
islands is the great preponderance of ferns, and next to
them of orchideie. The followin<'- ti.iiures are taken from
446 ISLAND LIFE part it
Mr. Baker's Flora for Mauritius and the Seychelles, and
from an estimate by M. Frappier of the flora of Bourbon
given in Maillard's volume already quoted : —
Mauritms, d'C. Bourbon.
Ferns 168 ' Ferns 240
Orchidefc 79 Orchideee 120
Gramineffi 69 Grammes 60
Cyperacea^ 62 Compositge 60
Rubiaceoe 57 Leguminosse 36
Euphorbiacete 45 Rubiacese 24
Cornpositse 43 Cyperacese 24
Leguminosffi 41 Enphorbiace;e ... 18
The cause of the great preponderance of ferns in oceanic
islands has already been discussed in my book on Tropical
Nature ; and we have seen that Mauritius, Bourbon, and
Ptodriguez 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,
the reverse of what occurs in remoter oceanic islands, may
be in part due to analogous causes. Their usually minute
and abundant seeds would be as easily carried by the wind
as the spores of ferns, and their frequent eiDij^hytic habit
affords them an endless variety of stations on which to
vegetate, and at the same time removes them in a great
measure from the competition of other jolants. When,
therefore, the climate is sufficiently moist and equable, and
there is a luxuriant forest vegetation, we may expect to
find orchids plentiful on such tropical islands as possess
an abundance of insects adapted to fertilise them, and
Avhich are not too far removed from other lands or conti-
nents from which their seeds might be conveyed.
Condudiiig Remarks on Madagctscar and the Mascarene
Islanch. — There is probably no portion of the globe that
contains within itself so many and such varied features of
interest connected with geographical distribution, or which
so well illustrates the mode of solving the problems it
presents, as the comparatively 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
cnAi'. XIX THE MADAC4ASCAR GROUP 447
Aldabra; in the Seychelles we have the fragments of
another very ancient island, which may perhaps never
have been continental; in' Mauritius, Bourbon, and
Rodriguez we have three undoubtedly oceanic islands;
while in the extensive banks and coral reefs of Cargados,
Saya de Malha, the Chagos, and the Maldive 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 have depths of 2,500 fathoms and
upwards, which renders it very improbable that there has
ever been here a continuous land surface, at all events
during the Tertiary or Secondary periods of geology.
It is most interesting and satisfactory to find that this
conclusion, arrived at solely by a study of the form of the
sea-bottom and the general principle of oceanic per-
manence, is fully supported by the evidence of the organic
productions of the several islands ; because it gives us
confidence in those principles, and helps to suj^ply us with
a practical demonstration of them. We find that the
entire group contains just that amount of Indian forms
which could well have passed from island to island ; that
many of these forms are slightly modified species, in-
dicating that the migration occurred during late Tertiary
times, while others are distinct sjenera, indicatino- a more
ancient connection ; but in no one case do we find animals
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 such an actual land-connection, are totally wanting.
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 api)lies equally to the
affinity of the Insectivora of Madagascar and Cuba ; the
snakes (Herpetodryas, &c.) of Madagascar and America ;
and the lizards (Cryptoblepharus) of Mauritius and
Australia. To suppose, in all these cases, and in many
others, a direct land-connection, is really absurd, because
448 ISLAND LIFE part ii
we have the evidence afforded by geology of wide,
differences of distribution directly we pass beyond the
most recent deposits ; and when we go back to Mesozoic —
and still more to Palaeozoic — times, the majority of the
groups of animals and plants appear to have had a world-
wide range. A large number of our European Miocene
genera of vertebrates were also Indian or African, or even
American ; the South American Tertiary fauna contained
many European types ; while many Mesozoic reptiles and
mollusca ranged from Europe and North America to
Australia and New Zealand.
By very good evidence (the occurrence of wide areas of
marine deposits 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 mammals — 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
inland ; and thus, when the large mammalia from the
northern continent overran Africa, they were prevented
from reachinof Madao-ascar, which thenceforth was enabled
to develop its singular forms of low-type mammalia, its
gigantic ostrich-like ^pyornis, its isolated birds, its
remarkable 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 accept the results of geological and palseontological
science, and the ascertained facts as to the powers of
dispersal of the various animal groups ; to take full
account of the lav/s of evolution as affectinsf distribution,
. HAV. XIX THE MADAGASCAR GROUP 449
and of the various ocean dejiths as implying recent or
remote union of islands with their adjacent continents ;
and the result is, tliat wherever we possess a sufficient
knowledge of these various classes of evidence, we find it
possible to give a connected and intelligible explanation of
all the most striking peculiarities of the organic world.
In Madagascar we have undoubtedly one of the most
difficult of these problems; but we have, I thiidv, fairly
met and conquered most of its difficulties. The com-
plexity of the organic relations of this island is due, partly
to its having derived its animal forms from two distinct
sources — from one continent through a direct land-con-
nection, and from another by means of intervening islands
now submerged ; but, mainly to the fact of its having
been separated from a continent which is now, zoologically,
in a very different condition from that which prevailed
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 Cretaceous, period. Some of
these types have become altogether extinct elsewhere ;
others have spread far and wide over the globe, and have
survived only in a few remote countries — and esj)ecially in
those which have been more or less secured by their
isolated position from the incursions of the more highly-
developed forms of later times. This explains why it is
that the nearest allies of the Madaofascar 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 of the
long-continued isolation of all these countries that similar
forms (descendants of ancient types) are preserved in them.
Had the numerous suggested continental extensions con-
necting these remote continents at various geological
periods been realities, the result would have been that all
these interesting archaic forms, all these defenceless insular
types, would long ago have been exterminated, and one
comparatively monotonous founa have reigned over the
whole earth. So far from explaining the anomalous facts,
the alleged continental extensions, had they existed, would
have left no such facts to be exi)laincd.
G G
CHAPTER XX
ANOMALOUS ISLANDS : CELEBES
Anomalous Relations of Celebes — Physical Features of the Lsland^Zoo-
logieal Charaetm- of the Islands Around Celebes — The Malayan and
Australian Banks — Zoology of Celebes : Mammalia — Probable Derivation
of the ]\Iammals of Celebes — 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 Colour of Celebesian Butterflies —
Concluding Remarks — 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,
Haiti, Jamaica, and Porto Rico), Iceland, and perhaps
Celebes. The Antilles have been so fully discussed and
illustrated in 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 geological 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
OELEBKS 451
volcanoes; it is connected with the Britisli Islands and
with Greenland by seas less than 500 fatlionis deep; and
it possesses a few mammalia, one of which is peculiar, and
at least three peculiar species of birds. It was therefore
almost cei-tainly united with Greenland, and ])robably witli
Eurojje by way of Britain, in the early part of the 'I'ertiary
period, and tlius afforded one of the routes by which tliat
intermigration of American and European animals and
plants was effected which w^e know occurred during some
portion of the Eocene and Miocene periods, and prob-
ably also in the Pliocene. The fauna and flora of this
island are, however, so j)oor, and offer so few peculiarities,
that it is unnecessary to devote more time to their
consideration.
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 con-
tinental " ; but whose central position and relations both to
Asia and to Australia 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 wdth either of
the great continents. Although I have pretty fully dis-
cussed its zoological peculiarities and past history in my
Geographical DUtrihution of Animals, it seems advisable to
review the facts on the present occasion, more especially
as the systematic investigation of the characteristics of
continental islands we have now made will place us in a
better jDosition for determining its true zoo-geographical
relations.
PJiifsical Feat )i res of Celebes. — This large and still com-
paratively unexplored island is interesting to the geo-
grajiher on account of its remarkable outline, 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 pen-
insula 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 nortliern
peninsula and in the central mass, as well as iron, tin, and
cojjper in small (juantities ; so that there can be little
(J c; li
452
ISLAND LIFE
PART II
donbt tliat the inoiintain rano'es of the interior consist of
ancient stratified rocks.
MAP OF CELEBES AND TIIH SURROU^'DIXG ISLANDS. J
The depth of sea is shown by three tints : the lightest indicating less than 100 1
fathoms, the medium tint less than 1,000 fathoms, and the dark tint more than j
1,000 fathoms. The figures show depths in fathoms. i
It is not yet known whether Celebes is completely \
separated from the surrounding islands by a deep sea, but j
(iiAP. XX CELEBES KW
the facts at our command render it probable that it is so.
The northern and eastern portions of the Celebi-s Si-a liavc
been ascertained to be from 2,000 to 2,G00 fatlioms deep,
and such depths may extend over a consi(hrahlt' purtion of
it, or even be much exceeded in the centrt'. In tin"
Mohicca passage a single sounding on the (iilolu side gave
1,200 fixthoms, and a large part of the Molucca and l^anda
Seas probably exceed 2,000 fathoms. The southern portion
of the Straits of Macassar is full of coral reefs, and a
shallow sea of less than 100 fathoms extends from BorncM)
to within about forty miles of the western promontory of
Celebes ; but farther north there is deep water close to the
shore, and it seems probable that a deep channel extends
quite through the straits, which have no doubt been mucli
shallowed by the deposits from the great Bornean rivers as
well as by those of Celebes itself. Southward again, tlie
chain of volcanic islands from Bali to Timor appears to rise
out of a deep ocean, the few soundings we possess showing
depths of from 670 to 1,300 fathoms almost close to their
northern shores. We seem justified, therefore, in eon-
eluding that Celebes is entirely surrounded by a deep sea,
which has, however, become partially filled up by liver
deposits, by volcanic upheaval, or by coral reefs. Such
shallows, where they exist, may therefore be due tn
antiquity and isolation, instead of being indications »»f a
former union with any of the surrounding islands.
Zoolufjmd Character of the Islands around Celebes. — In
order to have a clear conception of the peculiar character
of the Celebesian fauna, we must take into account that of
the surrounding countries from which we may suppose it
to have received immigrants. These we may diviile
broadly into two groups, those on the west belonging to
the Oriental region of our zoological geography, and tli«is<-
on the east belonging to the Australian region. ( M' tli.
first group Borneo is a typical representative; and troni its
proximity and the extent of its opposing coasts it is tljc
island which we should expect to show most resemblance
to Celebes. We have already seen tiiat the fauna of
Borneo is essentially the same as that of Southern Asia,
and that it is excessively rich in all the Malayan types ol'
454 ISLAND LIFE
mammalia and birds. Java and Bali closely resemble
Borneo in general character, though somewhat less rich
and with several peculiar forms ; wdiile the Philippine
Islands, though very much poorer, and with a greater
amount of speciality, yet exhibit essentially the same
character. These islands, taken as a wliole, may be
described as having a fauna almost identical wdth that of
Southern Asia ; for no family of mammalia is found in the
one which is absent from the other, and the same may be
said, with very few and unimportant exceptions, of the
birds ; wdiile hundreds of genera and of species are common
to both.
In the islands east and south of Celebes — the Moluccas,
New Guinea, and the Timor group from Lombok east-
ward— 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 four, and of these it is doubtful
whether two have not been introduced by man. We also
hnd here four fomilies 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, wdiere 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 fathoms below the surface) which
^ Families of Malayan Birds not Families of Moluccan Birds not
found ill islands Fast of found in islands West of
Celebes. Celebes.
Trogloilytidse. Paradiseida;.
Sittidse. Melipliagida?.
raridse. Cacatuidae.
Liotrichida-. Platycercidse.
Pliylloniithidi.i;. Trichoglossidic
Eurylsemidai. Nestoridse.
Picidse.
Indicatoridse.
Megalaiinida;.
Trogonida;.
Pliasianida;.
CELEBES
stretches out from the Siamese and Malayan peuinsula as
far as Java, Sumatra, Borneo, and the Philip])inc's. To
the east another bank unites New Guinea and tlic Papuan
Islands as far asAru, Mysol, and Waigiou, with Australia ;
while the Moluccas and Timor groups are surrounded by
much deeper water, whicli forms, in the Banda and
Celebes Seas and perhaps in other parts of this area, great
basins of enormous depths (2,000 to 3,000 fathoms or even
more) enclosed by tracts under a thousand f\ithoms, 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 agi-eeing with
New Guinea in their forms of life, yet strikingly deficient
in many important groups, and exhibiting an altogether
poverty-stricken appearance as regards the higher animals.
It is a suggestive fact that the Philippine Islands bear an
exactly parallel relation to Borneo, being equally deficient
in many of the higher groups ; and here too, in the Sooloo
Sea, we find a similar enclosed basin of great depth.
Hence we may in both cases connect, on the one hand,
the extensive area of land-surface and of adjacent shallow
sea with a long period of stability and a consequent rich
development of the forms of life ; and, on the other hand,
a highly broken land-surface with the adjacent seas of
great but very unequal depths, with a period of distur-
bance, probably involving extensive submersions of the laud,
resulting in a scanty and fragmentary vertebrate fauna.
Zoology of Cclehes. — The zoology of Celebes differs so
remarkably from that of both the great di\isions of the
Archipelago above indicated, that it is very ditficult to
decide in which to place it. It possesses only about
sixteen species of terrestrial mammalia, so that it is at
once distinguished from Borneo and Java by its extreme
poverty in this class. Of this small number four belong
to the Moluccan and Australian famia — there being two
marsupials of the genus Cuscus, and two forest rats said
to be allied to Australian types.
456 ISLAND LIFE
The remaining twelve species are, generally speaking,
of Malayan or Asiatic types, but some of them are so
peculiar that they have no near allies in any part of the
world; while the rest are of the ordinary Malay type or
even identical with Malayan species, and some of these
may be recent introductions through human agency.
These twelve species of Asiatic type will be now
enumerated. They consist of five peculiar squirrels — a
group unknown farther east ; a jDeculiar species of wild
pig ; a deer so closely allied to the Cervtcs hiiipelaplms of
Borneo that it may well have been introduced by man
both here and in the Moluccas; a civet, Viverra
tangahmr/a, common in all the Malay Islands, and also
perhaps introduced ; the curious Malayan tarsier (Tarsms
spectrum) said to be only found in a small island off the
coast ; — and besides these, three remarkable animals, all of
large size and all quite unlike anything found in the
Malay Islands or even in Asia. These are a black and
almost tailless baboon-like ape (CynajntJicus 7iigrcscens) ;
an antelopean buffalo {Anoa deprcssicornis), and the
strange babirusa {Babirusa aJfurus).
None of these three animals last mentioned has any
close allies elsewhere, and their presence in Celebes may
be considered the crucial fact which must give us the clue
to the past history of the island. Let us then see what
they teach us. The ape is apparently somewhat in-
termediate between the great baboons of Africa and the
short-tailed macaques of Asia, but its cranium shows a
nearer approach to the former group, in its flat projecting
muzzle, large superciliary crests, and maxillary ridges.
The anoa, though anatomically allied to the buffaloes, ex-
ternally 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 upwards like horns, forming a spiral curve
over the eyes, instead of downwards, as in all other
mammalia. An approach to this peculiarity is made by
the African wart-hogs, in which the uj^per tusk grows out
laterally and then curves up ; but these animals are not
otherwise closely allied to the babirusa.
CHAP. XX OET.KBES 457
Prolahlc Derivation of the Mctmvicils of Celele^. — 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 as the mono-
tremes and marsupials have been preserved in Australia,
and so many of the lemurs and Insectivora in ^Iada<;ascar.
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, remains 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 have the choice of two
theories : — either that the original island has since its
separation been greatly reduced by submersion, so as to
lead to the extinction of most of the higher land animals ;
or, that it originally formed part of an independent land
stretching 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 sejjarated
by narrow straits that a few mammals might find their
way across. The latter supposition appears 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 understand the c«»mi)lete
absence of the arboreal monkeys, of the Insectivora, and <>t
the very numerous and varied Carnivora and Rodents of
Borneo, all of which except the squirrels are entirely un-
represented in Celebes by any peculiar and ancient forms.
The question at issue can only hv finally di'tcrmined by
geological investigations. If Celebes has once fornu-il part
of Asia, and participated in its rich mammalian fauna,
which has been since destroyed by submergence, then some
458 ISLAND LIFE pakt ii
remains of this fauna must certainly be preserved in caves
or late Tertiary 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 have ever
reached the island, then no such remains will be discovered,
and there need be no evidence of any great and extensive
subsidence in late Tertiary times.
Birds of Celebes. — 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 the island of Celebes itself.
Considerably more than half of these (ninety-four species)
are peculiar to it ; twenty-nine are found also in Borneo
and the other Malay Islands, to which they specially
belong; while sixteen 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 pre-
ponderance of western over eastern species of birds
inhabiting Celebes, though not to quite so great an
extent as in the mammalia ; and the inference to be drawn
from this fact is, simply, that more birds have migrated
from Borneo than from the Moluccas — which is exactly
what we might expect both from the greater extent of the
coast of Borneo opposite 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
Celebesian 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 information. The ninety-four peculiar species
above noted belong to about sixty-six genera, of which
about twenty-three are common to the whole Archij^elago,
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 j^ro-
CELEBES 4oy
portion does not differ nnicli from that affDidcd l)v the
non-peculiar species; and it teaclies us that, for a consider-
able period, Celebes has been receiving* immigrants from
all sides, many of which have liad time to become modified
into distinct representative species. These evidently
belong to the period during whicli Borneo on the one side,
and the Moluccas on the other, have occu|)ied very mucli
the same relative position as now. There remain tlie
twelve peculiar Celebesian genera, to which we must look
for some further clue 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 Cckhc>i. — First we have Artamides,
one of the Campephagime or caterpillar-shrikes — a n(jt
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 kingtishers —
Monachalcyon and Cittura — seem alUed, the former to the
widespread Todiramphus and to the Caridonax ofLombok,
the latter to the Australian Melidora. Another kim-tisher,
Oeycopsis, combines the characters of the Malayan Ceyx
and the African Ispidina, and thus forms an example of an
ancient generalised form analogous to what occurs among
the mammalia. Streptocitta is a peculiar form allied to
the magpies ; while Basilornis (found also in Ceram),
Enodes, and Scissirostrum, are very peculiar starlings, the
latter altogether unlike any other bird, and perhaps form-
ing a distinct sub-family. Meropogon is a peculiar bee-
eater, allied to the Malayan Nyctiornis ; Rhamphococyx is
a modification of Phienicophaes, a Malayan genus of
cuckoos ; Prioniturus (found also in the Phili))pines) is a
genus of parrots distinguished by ra(iuet-fornied tail
feathers, altogether unique in the order; while Megace-
phalon is a remarkable and very isolated form ^A' the
Australian 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, we find f«»ur binls
which have no near allies at all, but aj)pear to l)e either
ancestral forms, or extreme modifications, of Asiatic or
460 ISLAND LIFE
African birds— Basilornis, Enodes, Scissirostrum, Ceycopsis.
Tliese may fairly be associated with the baboon-ape,
anoa, and babirusa, as indicating extreme antiquity and
some communication with the Asiatic continent at a period
when the forms of life and their geographical distribution
differed considerably from what they are at the present
time.
But here again we meet with exactly the same difficulty
as in the mammalia, in the comparative poverty of the
types of birds now inhabiting Celebes. Although the pre-
ponderance of affinity, especially in the case of its more
ancient and peculiar forms, is undoubtedly with Asia
rather than with Australia ; yet, still more decidedly than
in the case of the mammalia, are we forbidden to suppose
that it ever formed a part of the old Asiatic continent, on
account of the toPil absence of so many important and
extensive groups of Asiatic birds. It is not single species
or even genera, but whole families that are thus absent,
and among them families which are pre-eminently char-
acteristic of all tropical Asia. Such are the TimaliidaB, or
babblers, of which there are twelve genera in Borneo, and
nearly thirty genera in the Oriental Region, but of which
one species only, hardly distinguishable from a Malayan
form, inhabits Celebes ; the Phyllornithidie, or green
bulbuls, and the Pycnonotida?, or bulbuls, both absolutely
ubiquitous in tropical Asia and Malaya, but unknoAvn in
Celebes ; the Eurylaemidge, or gapers, found everywhere in
the great Malay Islands ; the Megalajmida?, or barbets ; the
Trogonidae, or trogons ; and the Phasianida^, or pheasants,
all pre-eminently Asiatic and Malayan but all absent from
Celebes, with the exception of the common jungle-fowl,
which, owing to the passion of Malays for cock-fighting,
may have been introduced. To these important families
may be added Asiatic and Malayan genera by the score ;
but, confining ourselves to these seven ubiquitous families,
Ave must ask, — Is it possible, that, at the period when the
ancestors of the peculiar Celebes mammals entered the
island, and Avhen the forms of life, though distinct, could
not have been quite imlike those now living, it could
have actually formed a part of the continent without
cHAr. XX CELEBES 4bl
possessing ropreseiita fives of tlie oroatoi- ]>art of tlicso
extensive and important taniilios of birds? To got rid
altogether of such varied and dominant types of bird-lifr
hy any subsequent process of submersion is more difficult
than to exterminate mammalia; and we are tliereforc again
driven to our former conclusion — that the present lan<l of
Celebes has never (in Tertiary times) been united to tlie
Asiatic continent, but has received its population of Asiatic
forms by migration across narrow straits and intervening
islands. Taking into consideration the amount ofaffinitv
on the one liand, and the isolation on the otlier, of tlie
Celebesian fauna, we may probably place the period of this
earlier migration in the early part of the latter lialf of the
Tertiary period, that is, in middle or late Miocene times.
Celebes not Strictly 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 former land-connection with Australia or New
Guinea, or even with the Moluccas. The numerous
marsupials of those countries are all wanting in Celebes,
except the phalangers of the genus Cuscus, and theso
arboreal creatures are very liable to be carried across
narrow seas on trees uprooted by earthquakes or Hoods.
The terrestrial cassowaries are equally absent ; and thus
we can account for the presence of all the Moluccan or
Australian types actually found in Celebes without sup-
posing any land-connection on this side during the Tertiary
jDeriod. The presence of the Celebes ape in the island of
Batchian, and of the babirusa in Bourn, can be sutheiently
explained by a somewhat closer approximation of the
respective lands, or by a few intervening islands which
have since disappeared, or it may even be due to human
agency.
If the explanation now given of tlie peculiai* features
presented by the fauna of Celebes be the correct one, we
are fully justified in classing it as an '• anomalous islaml,"
since it possesses a small but very remarkable mammalian
fauna, without ever having been directly united with any
462 ISLAND LIFE
continent or extensive land ; and, both by what it lias and
what it wants, occupies such an exactly intermediate
position between the Oriental and Australian regions that
it will perhaps ever remain a mere matter of opinion with
which it should properly be associated. Forming, as it
does, the western limit of such typical Australian groups
as the Marsupials among mammalia, and the Tricho-
giossidge and Meliphagidas among birds, and being so
strikingly deficient in all the more characteristic Oriental
families and genera of both classes, I have always placed
it in the Australian Region ; but it may perhaps with
equal propriety be left out of both till a further knowledge
of its geology enables us to determine its early history
with more precision.
Peculiarities of the Insects of Cclehes. — 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 very 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 Linnean Society — republished in my
Contributions to the Theory of Natural Selection, — while
others have been discussed in my Geogortiihical Dis-
trihution of Animals (Vol, I. p. 434) — I will only here
briefly refer to them in order to see whether they accord
with, or receive any explanation from, the somewhat novel
view of the past history of the island here advanced.
The general distribution of the two best known groups
of insects — the butterflies and the beetles — agrees very
closely with that of the birds and mammalia, inasmuch
as Celebes forms the eastern limit of a number of Asiatic
and Malayan genera, and at the same time the western
limit of several Moluccan and Australian 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 butter-
flies 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
CHAP. XX CELEliES 463
Rycatcher (Myiakstr^i liclianthra), a flower-pecker ( Varlni-
(flo^m aurcolimhatcC)y a finch {Mnnia hrtfn'/iciccjjs), and a
roller (Coracias tcmminchii), all closely allied to Indian
(not Malayan) species, — all the genera, exce])t Munia.
being, in fact, unknown in any Malay island. An exactly
parallel case is that of a bnttertly of the genns Diclior-
rhagia, which has a very close ally in the Himalayas, but
nothing like it 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 allied forms, in the Himalayas; and in both in-
stances they can only be explained by going back to a
period when the distribution of these forms was very
different from what it is now.
Peculiarities of Shape and Colour in Celehesian Butter-
flies.— Even more remarkable are the peculiarities of shape
and colour in a number of Celehesian butterflies of different
genera. These are found to vary all in the same manner,
indicating some general cause of variation able to act upon
totally distinct groups, and produce upon them all a com-
mon result. Nearly thirty species 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 in
any other part of the globe ; and whatever may have been
its cause, that cause must certainly have been long in
action, and have been confined to a limited area. We
have here, therefore, another argument in favour of the
long-continued isolation of Celebes from all the surround-
ing islands and continents — a hypothesis which we have
seen to afford the best, if not the only, explanation of its
peculiar vertebrate fauna.
Concluding Bcmarls. — If the view here given of the
origin of the remarkable Celehesian fiuma is correct, we
have in this island a fragment of the great eastern
^ For outline figures of the chief types of these butterflies, see my Mala ij
Archipelago, Vol. I. p. 441, or p. 21 () of the tenth edition.
464
ISLAXD LIFE
continent which has preserved to lis, 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
characterise its insects, it is, so far as yet known, abso-
lutely unique. Unfortunately 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 penetrate to the
forest-clad mountains of its interior.
APPENDIX TO CHAPTER XX
The following list of the Land Birds of Celebes ami the adjac^'iit islands
which partake of its zoological peculiarities, in which are incorporated all
the species discovered up to 1890, has been drawn up from the following
sources : —
1 . A List of the Birds known to inhabit the Island of Celebes. By Arthur,
Viscount Walden, F.R.S. (Trans. Zool. Soc. 1872. Vol. viii. pt.
ii.)
2. Intorno al Geuerc Hermotimia. (Rclib.) Nota di Tommaso Salvador!.
(Atti della Reale Accademia delle Scienzedi Torino. Vol x. 1874.)
3. Intorno a due Collezioni di Ucelli di Celebes — Xote di Tommaso
Salvadori. (Annali del Mus. Civ, di St. Nat. di Genova. Vol. vii.
1875.)
4. Beitriige zur Ornithologie von Celebes und Sangir. Von Dr. Friedrich
Briiggemann. Bremen, 1876.
5. Intorno a due piccole Collezioni di Ucelli di Isolc Sanghir c di Tiforc.
Nota di Tommaso Salvadori. (Annali del Mus. Civ. di St. Nat. di
Genova. Vol. ix. 1876-77.)
6. Intorno alle Specie di Nettarinie delle ilolucche e del Gruppo tli
Celebes. Note di Tommaso Salvadori. (Atti della Reale Accad.
delle Scienze di Torino. Vol. xii. 1877.)
7. Descrizione di trc Nuove Specie di Ucelli, c note intorno ad altre poco
conosciute delle Isole Sanghir. Per Tommaso Salvadori. (L. c.
Vol. xiii. 1878.)
8. Field Notes on the Birds of Celebes. Bv A. B. Mever, M. D. , .S:c. (Ibis,
1879.)
9. On the Collection of Birds made by Dr. Meyer daring Ids Expedition
to New Giunea and some neighbouring Islands. By R. Boulder
Sharpc. (Mitth. d. kgl. Zool. Mus. Dresden, 1878. Heft 3.)
New species from the Sula and Sanghir Islands arc described.
lU. List of Birds from the Sula Islands (East of Celebes) with Descrijitious
of the New Species. By Alfred Russel AVallace, F.Z.S. (Pa<c.
Zool. Soc. 1862, p. 333.)
11. The Zoological Record, and " The Ibis " to 1890.
11 11
I
LIST OF LAND BIRDS OF CELEBES
N.B. — The Species marked with an* are not included in Viscount JFalden's
list. For these only, an authority is usually given.
Celebes
TURDID^.
1. Geocichla erythrouota ...
2. Monticola solitaria
Sylviid^.
3. Cisticola ciu'sitaiis
4. ,, grayi
6. Acrocephalns orientalis...
*6. ,, insularis ...
7. Pratincola caprata'
*S. Gerygone flaveola (Cab.) x (Meyer)
TlMALIlD.«.
9. Trichostoina celebeuse ...
Pycnonotid^e.
*10. Criniger longirostris(Wall.)
11. ,, aureus (Wald.)...
Oriolid^.
12. Oriolus celebensis
foriuosus (Cab.) ...
frontalis (Wall.)...
Campephagid^.
15. Graucalus atriceps
16. ,, leucopygius ...
17. ,, teniniinckii ...
18. CampeiJhaga niorio
*19. ,, melanotis...
*20. „ salvadorii (Sharpe],
21. Lalage leucopygialis
*22. ,, dominica
23. Artauiides bicolor
*24. ,, schistaceus (Sharpe)
DlCRURID^.
25. Dicrurus leucops
*26.
*27.
axillaris (Salv.)
pectoralis (Wall.)
X (Meyer)
Sula Is.
Sanghirls.
X
-
X (Salv.)
X
X
x(13rugg.)
X
X (Wall.)
X
X
-
X
Range and Remarks
Pliil., China, Japan
Assam
China, Japan
Moluccas
Asia, Java, Timor
(Near G. sulphurea,
Timor)
Oriental genus (near
Bouru S25.)
(Var of 0. coronutus,
Java)
(Var. of Philipii. sp.)
Ceram, Flores
Molucca.s
Java
CHAP. XX
LIST OF LAND BIRDS OF CELEBES
467
Celebes i Sula Is. Sanghirls. Range and Remarks
MUSCICAPID^.
28. Cyornis rufigula x
29. ' ,, banj'unias X
30. !Myialestes hcliauthea ... x
31. Hypothyniis iMiella x
32. ' ,, lueiiadcnsis? X
*33. Munarcha coiiinmtata
(13rugg.)
*34. ,, ciuex^ascens ...
Pachycephalid^.
35. Hylocliaris sulfuriveiitra
•3(5. Paclivccphala lineolata
(Wall.)
*37. raclivceiiliala rutescens
(Wall.)
*38. Pacliycepliala clio (Wall.)
Laniid.*;.
*39. Lauius maguiroslris(Mej'er)
CORVID.K.
40. Corvus cnca
*41. ,, annectens (Brugg.)
42. ,, (Gazzola)typica...
43. Streptocitta caledonica...
44. ,, torqiiata ...
*45. (Charitornis)albertii«(Sclil.)
Meliphagid.«.
40. Myzoniela cliloroptera ...
Nectariniid.e.
47. Antlireptes celebensis
(Shelley) X
48. Chalcostethia porpbyolsema x
*49. ,, auriceps i
*bO. „ saiigirensis(Meyer.|
51. Cj'i'tostoinus frenatus ...
I
52. Nectaropliila gvayi j
53. ^Ethoiiyga flavostriata ... I
*54. ,, bcccarii (Salv.) ...
*55. ,, (Uiyvenbodei (Sclil.)i
DlC/EIDiE.
56. Zostevops iiiterinedia
57.
58.
*59.
*60,
61.
atrifrons.
Dicaeuni celebicuiu
,, saiighirense (Salv. )
,, uehrkoriii (Bias.) \
Pachyglossa aureolimbata j
HiRUNDlNID.E.
62. Hiruiulo gultiiralis.
63. ., j avail ica .
Ploceid^.
64. Muiiia oiy/ivora
n.soria .
aolucca.
X (Wall.)
X
X (Wall.)
X
Java and Borneo
(Indian ally)
Moluccas
Bourn
Bourn
Bourn
Java
Java
(Nearest M. »an-
guinolenta of Aus-
tralia)
Siaiii, Malaya
Ternate
Moluccas and N.
Guinea
(An Oriental genus)
Lonibock
Indian n-gion
Indo-Malaya
Java
Java
Molueais
U U Z
468
ISLAND LIFE
Celebes Sula Is. Sanghirls.
x(Bnigg.)
67. Munia brunueiceps ! X
*6S. ., jagori x (Meyer)
Sturnid.e.
69. Basilornis celebensis ... ; x
70. Acridotheres cinei-eiis ... j x
71. Sturnia pj-rrhogenys ... x
72. Calomis iieglecta ...
*73. ,, iiietallica ...
74. Euodes erythrophrys
75. Scissirostrum jiagei...
Artamid^.
76. Artainns luouaclius
77. ,, leucorhyuchus..
MOTACILLID.E.
78. Corydalla gustavi
79. Budytes viridis
*80. Calobates melauope
(=Motac. siilfurea, Brugg.)
PlTTID^.
81. Pitta forsteui
*S2. ,, sanghirana (Sclil.)...
83. ,, celebensis
*84. ,, palliceps (Bnigg.)...
*85. ,, coeruleitorques(Salv.)
*S6. ,, ireiia(=crassirostris)
P1CID.E.
87. Aloplioiierpes fulvns
*88. ,, Wallace! ...
89. Yungipicus temminckii...
CUCULID.E.
90. Khamphococcyx calorhyu-
clms
91. PjTrhoceiitor celebensis..
92. Centropus affinis
93. ,, javanensis ...
91. Cuculus canorus
9j. Cacomautes lanceolatus..
96. ,, sepulcliralis .
97. Hierococcyx crassirostris
98. Eudynauiis melanovhyncha
*99. „ facialis (Wall.)
*100. ,, orien talis
101. Scythroiis novctthoUaudiae
C0RACI1D.E.
102. Coracias temminckii
103. Eurystomus orien talis ...
Meropid^.
104. Meropogon forsteni
105. Merops ])hilippinus
106. ,, ornatus
Alcedinid.-e.
107. Alcedo moluccensis
asiatica
K var.
(Wall.) —
X (Wall.) ; —
108.
Range and Remarks
X (Brugg.)
(Near M. ruhronUjra,
India)
Philippines
Malaya
Moluccas
Malay Archipel.
Java, Molucca!-
China, Philipp.
Tiuiur, Ternatc ?
Java
Java, Borneo
Java
Moluccas ?
Moluccas, &c.
Asia
Oriental region
Java, Australia
Moluccas
ludo-Mulayj
riiAP. XX
[JST OF LAND BTRDS OF rKLrr.ES m
Sul:i Is. San.^liirTs. 'Rnnsi' ftii'l R<-iiiftr'ks
C'.-l.'bcs
iiiolaiio-
100. Pelargnpsis
rliynclia
"1 10. Ceyx wallacei (Sharp'O...
111. Ce'ycopsis falUix
11-2. ITrilryon f-liloiis
li:i. ., saiicta !
114. ., forstciii i
lir.. „ vufa j
lie. :Nr(.iiachalcyon princeps \
^IIT. ,, cyanoccpliala(Brngg.)
lis. Cittnra cyanotis
'110. ,, saiii;liivciisis(Sclil.)
BrCFROTID.E.
1-20. Tlyih-ocissa exarata
1-21. Craiiorhinr.s rnssidix ...
CAPRIMTTLOlD.f:.
122. Caprimulgns affinis
123. ,, sp
124. Lyncornis inacro]itcviis . j
Cypselid.'E.
125. DeiKlrochelidon wallacoi
12*1. Collocalia esculenta ...
127. ,, fncipliaga ...
12<^. Chfetiira gigaiitea
PSITTACI.
120. Cacatna snlplniroa
130. Pi'iciiitunis plat urns ...
1.31. „ rtavicans ...
*132. Platycercns dorsalis, var.
133. Tanygnathus laiiUori ...
*l?A. ., iiiegalovliyncluiK
»1.3.'). ,, luzonieiisis ...
136. Loriculiis stigmatus ...
*137. ,, quadvicolov O^^al*^^-
1.3S. ,, selateri
130. ., cxilis
*14n. „ cataniciie(Sc'lil.)...
141 Trichoglossus oniatiis ...
*14-2. ., flavoviri(lis(Wall.)
143. ,, ineyeri
*144. Eos liistrio=E. coccinoa
CoI,UMB.E.
14.'). Trevon voriiaii>
■iscioauda
147. Ptilopns formosiis
14S. ., melaiiocoi>lialus
149. ,, gidaiis
*150. ., lisclieri(Brugg.)
151. Carpopliaga paiilina ...
(Allir.l tM Mot. -p.)
.\1! .\rcliip.l.
.Ml .\rcliip.-l.
X (Wall.)
x(Brngg.)
SM. to Am Is.
India, .Java
India. Java
Loiiil'ook, Floros
N. Gnin(a?
Molucca.s. All i.slaiid
near Meiiailo
(:Moyer)
Togian Is., Gulf of
Tiiiiiiiii
X var.
Sanglii-
reiisi.s
X var.
Xantlior-
1-1 loa,
8alv.
Malacca. Java,
Pl.ilipp.
.Java, Louiliock
470
ISLAND LIFE
Celebes | Sula Is. Sanghirls.
*152. Carpophaga pulchella ...
(Wald.)
153. ,, concinna
154. ,, rosacea
*155. ,, pfficiloiTlioa(Bnigg.)
156. ,, luctuosa ...
*157. ,, Viicolor ... ,
158. ,, rafliata ...
159. ,, forsteni ...
160. Macropygia albicapilla
161. ,, macassariensis
*162. ,, sang]iirensis(Salv.)
16.S. Turacoena inenadensis ...
*164. Reinwavdtsenas rein-
wardti
165. Turtur tigrina
166. Chalcophaps ste]ihani ...
167. ,, indica
168. Pldogajnas tristigmata...
169. Geopelia .striata""
170. Calsenas nicoharica
Galling.
171. Gallus Imnkiva
172. Coturnix jiiinima
173. Turnix rufilatn.s
*174. ,, beccarii (Salv.)...
175. -Megapodius gilbei-ti ...
176. Megacephalon inallco ...
ACCIPITRES.
177. Circus assiinilis
178. Asturgriseiceps
^179. ,, temurostris(Brugg.
180. ,, rhodogastra
181. ,, trinotata
182. Accipiter sulaensis(Schl.
183. ,, soloensis
184. Neopus malayen.sis
X (Salv.)
X (Meyer)
X Meyer
X
X
X
X
185.
186.
187.
188.
ISO.
190.
191.
192.
193.
194.
195.
196.
197.
Spizaetus lanceolatns ...
Haliaetus leucogaster ...
Spilornis rufipectus
Butastur liventer
,, indicus
Haliastur leucosteriius..
i\Ii]vus affinis
Elanus liypoleuci^s
Pernis ptilorhyncha (var.
celebensis)
Baza erythrotliorax
Falco severns
Cdrclineis moluccensis...
Polioaetus humilis
Strigid^.
198. Athene punctulata
199. ,, ochracea ...
200. Scops magicus
201. ,, menadensis ...
202. Ninox iaponicns ...
*203. ,, scutulata ...
204. Strix rosenbergi ...
Range and Remarks
X(Salv.)
Togian Is. (A))n. atid
Mag.Nat.Hst.,lS74.)
Ke Goram
Gilolo, Timor
New Gnin., iMolnccas
i\Ioluccas (tXewGuin.
Malaj^a, Moluccas
New Guinea
India and Archipel.
China, Java, Lom-
bock
Malacca and New
Guinea
Java, Timor
(Var. of C. Chinensis)
Australia
I >\Ialacca & New Guin,
Nepaul, Sum. Java,
Moluccas
Oriental region
Java, Timor
India, Java
Moluccas, New Guin.
Australia
? Java, Borneo
(Var. Java, &c.)
All Archipel.
Java, Moluccas
India, Malava
Amboyna, &:c. ?
Flores, Madagascar
China, Japan
Malacca
CHAPTER XXT
ANOMALOUS ISLANDS : NEW ZEALAND
Position and Physical Features of New Zealand — Zoological Character of
New Zealand — jMamnialia — Wingless Birds Living and Extinct — Recent
Existence of the JSIoa — Past Changes of New Zealand deduced from
its "Wingless Birds — Birds and Reptiles of New Zealand — Conclusions
from the Peculiarities of the New Zealand Fauna.
The fauna of New Zealand has been so recently described,
and its bearing on the past history of the islands so fully
discussed in my 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
different point of view, and with some important fresh
material, which will enable us to arrive at more detiiiite
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 refereucc to one
of the most remarkable and interesting of insular faunas
was omitted.
The two great islands which mainly constitute New
Zealand are together about as large as the kiugilom (^f
Italy. They stretch over thirteen degrees of latitude in
the warmer portion of the south-tem])erate zone, their
extreme points corresponding to the latitudes of Vienna
and Cyprus. Their climate throughout is mild and
472
ISLAND LIFE
equable, their vegetation is luxuriant, and deserts or
uninhabitable regions are as completely unknown as in
our own islands.
The geological structiu^e of these islands has a decidedl}^
continental character. Ancient sedimentary rocks, granite,
and modern volcanic formations abound ; gold, silver, copper,
tin, iron, and coal are plentiful ; and there are also some
90
MAP SHOWINO DEPTHS OF SEA AROUND AUSTRALIA AND NEW ZEALAND.
The light tint indicates a deptli of less than 1,000 fathoms.
The dark tint ,, ,, more than 1,000 fathoms.
considerable deposits of early or late Tertiary age. The
Secondary rocks alone are very scantily developed, and
such fragments as exist are chiefly of Cretaceous age,
often not clearly separated from the succeeding Eocene
beds.
The ]30sition of New Zealand, in the great Southern
Ocean, about 1,200 miles distant from the Australian
'HAP. XXI NEW ZEALAND 473
continent, is very iRolated. It is snrronnded l)y ;i nioder-
atoly deep ocean; but the form of tlic sea-bottom is
peculiar, and may help us in tlie solution of some <>f tlir
anomalies presented by its livino productions. TIic line
of 200 fathoms encloses the two islands and extends their
area considerably; but the 1,000-fatliom line, wliicli in-
dicates the land-area that would be jtroduced if tlie sea-
bottom were elevated 6,000 feet, has a very remaikahle
conformation, extending in a broad mass Avestward and
northward, then sending" out a great arm leacliing to
beyond Lord Howe's Island. Norfolk Island is situated
on a moderate-sized bank, while two others, mucli more
extensive, to the north-west approach the great barrier
reef, which here carries the l,0n()-fathom line more than
300 miles from the coast. It is probable that a bank, less
than 1,500 fathoms below the surface, extends over this
area, thus forming a connection with tropical Australia
and New Guinea. Temperate Australia, on the otlier
hand, is divided from New Zealand by an oceanic gulf
about 700 miles wide and between 2,000 and 3,000 f;\thoms
deep. The 2,000-fathom line embraces all the islands
immediately round New Zealand as far as the Fijis to the
north, while a submarine plateau at a depth somewhere
between one and two thousand fathoms stretches soutli-
ward to the Antarctic continent. Judging from these
indications, we should say that the most probable ancient
connections of New Zealand were witli tropical Australia,
New Caledonia, and the Fiji Islands, and perhaps at a
still more remote epoch, with the great Southern continent
by means of intervening lands and islands ; and we sliall
find that a land-connection or near approximation in tliese
two directions, at remote periods, will serve to ex])laiii
i.^any 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
474 ISLAND LIFE part ii
considered to possess no indigenous 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 wonderfully
isolated, and seem to bear no j)redominant 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 apparent contradiction.
Mammalia of New Zealand. — The only undoubtedly
indigenous mammalia appear to be two species of bats,
one of which [Scotoijliilus tvJjerculatus) is, according to
Mr. Dobson, identical with an Australian form, while the
other {Mystacina tulereulccta) forms a very remarkable
and isolated genus of Emballonuridse, a family which
extends throughout all the tropical regions of the globe.
The genus Mystacina was formerly considered to belong
to the American Phyllostomidse, but this has been shown
to be an error.^ The poverty of New Zealand in bats is
very remarkable when compared with our own islands
where there are at least twelve distinct species, though
we have a far less favourable climate.
Of the existence of truly indigenous land mammals in
New Zealand there is at present no positive evidence, but
there is some reason to believe that one if not two species
may be found there. The Maoris say that before Europeans
came to their country a forest-rat abounded and was largely
used for food. They believe that their ancestors brought
it with them when they first came to the country ; but it
has now become almost, if not quite, exterminated by the
European brown rat. What this native animal was is still
somewhat doubtful. Several specimens have been caught
at different times which have been declared by the natives
to be the true Kiore Maori — as they term it, but these have
usually proved on examination to be either the European
black rat or some of the native Australian rats which now
^ Dobson on the Classification of Chiroptera [Ann. and Mag. of Nat.
Hist. Nov. 1875).
rHAP. xxT NEW ZEALAND 47.1
often lind tlieir way on board ships. But witliin tin- last
few years many skulls of a rat have been o])taine(l frmn tin-
old Maori cooking-plaees, and from a cave associated w ith
moa bones; and Captain Hutton, who has examined them,
states that they belong to a true Mus, but ditl'er fiom th('
Mh>^ rrfUifS. This animal might have been on the islands
when the Maoris first arrived, and in that case would Ix-
truly indigenous ; wdiile the Maori legend of their "an-
cestors " bringing the rat from their Polynesian home may
be altogether a myth invented to account for its presence
in the islands, because the only other land mannnal which
they knew — the dog — w^as certainly so brought. The
question can only be settled by the discovery of remains (.f
a rat in some deposit of an age decidedly anterior to the
first arrival of the Maori race in New Zealand.^
Much more interesting is the reported existence in the
mountains of the South Island of a small otter-like animal.
Dr. Haast has seen its tracks, resembling those of oui-
European otter, at a height of 3,000 feet above the sea in
a region never before trodden by man ; and the animal
itself w^as seen by two gentlemen near Lake Heron, about
seventy miles due west of Christchurch. 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 yelj)ing
sound and disappeared in the w^ater.- An animal seen so
closely as to be struck at with a wdiip could hardly have
been mistaken for a dog — the only other 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, point to an aquatic animal ; and if
it now frequents only the high alpine lakes antl streams,
this might explain wdiy it has never yet been captureil.
Hochstetteralso states that it has a native name — Waitoteke
— a striking evidence of its actual existence, wOiile a gentle-
man who lived many years in the district assures me that
^ Sec Bullev, "On the New Zealand Rat," Trans, of f fir X. '/. In^tilutf
(1870), Vol. III. |). 1, and Vol. IX. y. 348 : and Hutton, "On tliofli'o^-a-
phical Relations of the New Zealand Fauna," Trmis. X. Z. histU. 1872,
p. 229.
^ Hochstetter's New Zealand, j). Itil, note.
476 ISLAND LIFE
it is universally believed in by residents in that part
of New Zealand. The actual capture of this animal and
the determination 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.^
Wingless Birds, Living and Extinct — Almost equally valu-
able with mammalia in affording indications of geographical
changes are the wingless birds for which New Zealand is so
remarkable. These consist of four species of Apteryx,
called by the natives " kiwis/' — creatures which hardly look
like birds owing to the apparent absence (externally) of
tail or wings and the dense covering 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 dis-
tinct 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 only recently become ex-
tinct. These were much larger birds than the kiwis, and
some of them were even larger than the ostrich, a specimen
^ The animal described by Captain Cook as having been seen at Pick-
ersgill Harbour in Dusky Bay (Cook's 2nd Voyage, Vol. I. p. 98) may have
been the same creature. He says, "A four-footed animal was seen by three
or four of our people, but as no two gave the same description of it, I can-
not say what kind it is. All, however, agreed that it was about the size of
a cat, with short legs, and of a mouse colour. 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 Mhich " all agreed *' — the size and the dark colour — this descrip-
tion would answer well to the animal so recently seen, while the "short
legs " correspond to the otter-like tracks, and the thick tail of an otter-like
animal may 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 explanation ; while the actual exist-
ence of an unknown onimal in New Zealand of corresponding size and
colour is confirmed by this account of a similar animal having been seen
about a century ago.
(HAP. XXI NKW ZEALAND 47
of Dinornis maximus mouiited in the British Museum in
its natural attitude being eleven feet high. They agreed,
however, Avith the living Apteryx in the character of the
pelvis and some other parts of the skeleton, while in their
short bill and in some important structural features they
resembled the emu of Australia 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 deposits, in
old native cooking places, and even scattered on the sur-
face 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 tlie skin, as
well as the stones swallowed by the birds to assist diges-
tion, and eggs, some containing portions of the embryo
bird ; so that everything confirms the statements of the
Maoris — that their ancestors found these birds in abundance
on the islands, that they hunted them for food, and that
they finally exterminated them only a short time before
the arrival of Europeans." Bones of Apteryx are als(j found
fossil, but apparently of the same species as the living birds.
^ Owen, *'Oii the Genus Dinornis," Trans. Zool. Soc. \o\. X. p. 184.
Mivait, "On the Axial Skeleton of the Striitliionida3, " 2'ra/is. Zool. Soc.
Vol. X. p. 51.
- The recent existence of the Moa and its having been exterminated by
the Maoris appears to be at length set at rest by the statement of Mr.
John White, a gentleman who has been collecting materials for a history of
tlie natives for thirty-five years, who has been initiated by their i>riestsinto
all their 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 from old natives long before the controversy ou
the subject arose. He says that the histories and songs of the Maoris
abound in allusions to the ]\Ioa, and that they were able to give full
accounts of "its habits, food, the season of the year it was kiHed, its
appearance, strength, and all the numerous ceremonies whicli were e-nacted
by the natives before they began the hunt, tlie mode of liunting, huw iiit
U]), how cooked, and what wood was used in the cooking, witli an acrniiut
of its nest, and how the nest was made, where it usually lived, &i /' Two
pages are occupied by these details, but they arc only given from memory,
and ]\Ir. AVliite ])romises a full account from his ^ISS. Many of the di-tails
given corres])ond with facts ascertained from the discovery ol" nativi- cook-
ing itlaccs with Moas' bones; and it seems (juite incrediMi' tliat such an
elaborate and detailed account should br all invention. (See TrunMidions
of the New Zealand Institute, Vol. VIII. p. 79.)
478 ISLAND LIFE paiit ii
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 S2:)ecimens have been found under
a considerable depth of fluviatile deposits which may be of
Quaternary or even of Pliocene age ; but this evidently
affords us no ai^proximation to the time required for the
origin and development of such highly peculiar insular
forms.
Past Changes of New Zealand cleducccl from its Wingless
Birds. — It has been well observed by Captain Hutton, in
his interesting paper already referred to, that the occurrence
of such a number of species of Struthious birds living to-
gether in so small a country as New Zealand is altogether
unparalleled elsewhere on the globe. This is even more
remarkable when we consider 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 swamjD in the South Island,
where also three of the species of Apteryx occur. 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 dis-
trict. Thus, there appear to be two closely allied species
of ostriches inhabiting Africa and South-western Asia re-
spectively. 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 Aru 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 jDart 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 that fifteen species of wingless birds in
the small area of New Zealand, that the idea is at once
suggested of great geographical changes. Captain Hutton
points out that if the islands from Ceram to New Britain
riiAi'. XXI NEW ZEALAND 479
were to become joined together, we slioiild have ii lart'c
number of sj^ecies of cassowary (perhajis several mon- than
are yet discovered) in one land area. If now this land
were gradually to be submerged, leaving a central elevate* 1
region, the different species would become crowded together
in this 23ortion 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
separate species of cassoAvaries, in order that the connuon
ancestral form which afterwards became modified into tliesc
species, could have reached the places where they are now
found ; and this gives us an idea of the complete series of
changes through wdiicli New Zealand is believed to ha\e
passed in order to bring about its abnormally dense popula-
tion of wingless birds. First, we must suppose a land connec-
tion wdth 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 differentiated ;
thirdly, an elevation bringing about the union of thesi"
islands to unite the distinct sj^ecies in one area; and
fourthly, a subsidence of a large part of the area, leav-
ing the present islands wdtli the various species crowded
together.
If New Zealand has really gone through such a series of
changes as here suggested, some proofs of it might perhaps
be obtained in the outlying islands which were once, pre-
sumabl}^, joined with it. And this gives great importance
to the statement 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 Norfolk Island, in both of which it
is not improbable remains either of Apteryx or Dinornis
might be discovered.
So far we find nothing to object to in the speculations
of Captain Hutton, with which, on the contrary, we almost
Avholly concur ; but Ave cannot follow him when he goes on
to suggest an Antarctic continent uniting New Zealand and
Australia with South America, and ])robably also with
South Africa, in order to explain the existing distribution
480 ISLAND LIFE part ii
of struthious birds. Our best anatomists, as we have seen,
agree that both Dinornis and Aj^teryx are more nearly
alUed to the cassowaries and emus than to the ostriches
and rheas; and we see that the form of the sea-bottom
suggests a former counection with North Austraha and
New Guinea — the very region where these tyjoes most
abound, and where in all jDrobability they originated. The
suggestion that all the struthious birds of the world sprang
from a common ancestor at no very remote period, and
that their existing distribution is due to direct land com-
munication between the countries they noio inhabit, is one
utterly opposed to all sound principles of reasoning in
questions of geographical distribution. For it depends
upon two assumptions, both of which are at least doubtful,
if not certainly false — the first, that their distribution over
the globe has never in past ages been very different from
what it is now ; and the second, tliat the ancestral forms
of these birds never had the power of flight. As to the
first assumption, we have found in almost every case that
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 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 lemurs
of Africa and Asia had their ancestors in Europe, as had
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
remains, believed to be of struthious birds, are found in
the Eocene deposits of England ; and the Cretaceous rocks
of North America have yielded the extraordinary toothed
bird, Hesperornis, which Professor O. Marsh declares to
have been " a carnivorous swimming ostrich."
As to the second point, we have the remarkable fact
that all known birds of this group have not only the rudi-
ments of wing-bones, but also the rudiments of wings, that
is, an external limb bearing rigid quills or largely-developed
• HAi". XXI XEW ZEALAXD 481
plumes. In the cassowary these wing-feathers ar.- itiIuclmI
to \ong spines like porcupine-quills, while even in tlie
Apteryx, the minute external wing bears a series of nearly
twenty stiff quill-like feathers.^ These facts render it
almost certain that the struthious birds do not owe their
imperfect wings to a direct evohition from a reptilian type,
but to a retrogi-ade 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 keel-less sternum and rudimentary
wings — already existed side by side ; while in the still
earlier Arclia?opteryx of the Jurassic period we have a bird
with well-developed wings, and therefore i^robably with a
keeled sternum. We are evidently, therefore, very far
from a knowledge of the earliest 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 binls
acquired wings, and feathers, and some power of flight,
before they developed a keeled sternum, since w^e see that
bats with no such keel fly very well. Since, therefore, the
struthious birds all have perfect feathers, and all have
rudimentary wrings, wdiich are anatomically those of true
birds, not the rudimentary fore-legs of reptiles, and since
we know that in many higher groups 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 tlie very remote
ancestors of the rhea, the cassowary, and the apteryx, were
true flying birds, although not perhaps provided with a
keeled sternum, or possessing very great powers of flight.
But in addition to the possible ancestral power of flight,
we have the undoubted foct that the rhea and the emu
both swim freely, the former having been seen swimming
from island to island oft' the coast of Patagonia. Tliis,
taken in connection with the wonderful ac[uatic ostrich of
the Cretaceous period discovered by Professor Marsh, opens
1 See fig. in Trans, of K. Z. Institute, Vol. III., phite 12/'. fi?. 2.
482 ISLAXD LIFE
up fresh possibilities of" inigration ; while the immense
antiquity thus given to the group and their universal
distribution in past time, renders all suggestions of special
modes of communication between the parts of the globe
in which their scattered remnants nov: 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 New Zealand is concerned, we have nothing whatever
to do with any possible connection, b}^ way of a southern
continent or antarctic islands, w^ith South America and
South Africa, because the nearest allies of its moas and
kiwis are the casso wearies and emus, and we have distinct
indications of a former land extension towards North
Australia and New Guinea, wdiich is exactly what wt
require for the original entrance of the struthious type into
the New^ Zealand area.
Winged Birch and Lower Vcrtehmtcs of New Zealand. —
Having given a pretty full account of the New^ Zealand
fauna elsewdiere ^ I need only here j^oint out its bearing
on the hypothesis now advanced, of the former land-
connection having been with North Australia, New
Guinea, and the Western Pacific Islands, rather than
with tlie 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 dis-
tricts. As regards the peculiar New^ Zealand genera, all
whose affinities can be traced are allied to birds wdiich
belong to the tropical jDarts of the Australian region;
while the starling family, to' which four of the most
remarkable New Zealand birds belong (the genera
Creadion, Heterolocha, and Callreas), is totally wanting
in temperate Australia and is comparatively scarce in
the entire Australian region, but is abundant in the
Oriental region, w^th which New Guinea and the
Moluccas are in easy communication. It is certainly
a most suggestible fact that there are more than sixty
^ Ckograjyhkal Distribution of Ardmals, Vol. I., p. 450.
Ni:W ZEALAND 188
genera of birds peculiar to the Australian continent
(with Tasmania), many of them almost or quite con-
fined to its temperate portions, and that no single uiw
of these should be represented in temperate Now Zi-a-
land.^ The affinities of the living and more highly
organised, no less than those of the extinct and wing-
less birds, strikingly accord with the line of comminji-
f'ation indicated by the deep submarine bank connecting
these temperate islands witli the tropical jwrts of tho
Australian region.
The reptiles, so far as they go, are quite in accordance
with the birds. The hzards belong to two genera,
Lygosoma, which has a wide range in all the tropics as
well as in Australia ; and Naultinus, a genus peculiar
to New Zealand, but belonging to a family — Geckonida-
— spread over tlie whole of the warmer parts of the world.
Austraha, with New Guinea, on the other hand, has a
peculiar family, and no less than twenty-one peculiar
genera of lizards, many of which are confined to its
temperate regions, but no one of them extends to tem-
perate New Zealand.^ The extraordinary lizard-like
Hattcria punctata of New Zealand forms of itself a
distinct order of reptiles, in some respects intermediate
between lizards and crocodiles, and having therefore no
affinity wdth any living animal.
The only representative of the Amphibia in New
Zealand is a solitary frog of a peculiar genus (Liopclma
hochstctteri) ; but it has no affinity for any of tlic
Australian frogs, which are numerous, and belong to
eleven different families ; while the Liopelma belongs
^ In my GeogrcqMccd Distribidioii of Animals [I. p. 541) I hav«\criveii
two peculiar Australian genera [Ortlioiiyx and Tribonyx) as occurring in
Xew Zealand. But the former has been found in New Guinea, while the
Xew Zealand bird is considered to form a distinct genus, Clitonyx : and
the latter inhabits Tasmania, and was recorded from New Zealand tlirough
an error. (Sec //^/>, 187-3, p. 427.)
- Tlie peculiar genera of Australian lizards according to Boulenger's
British :Museum Catalogue, are as follows :— Family Gf.ckonid^e : Nci>h-
rurus, Rhynchcedura, lleteronota, Diplodactylus, (Edura. Family Pygo-
roDlD.E (peculiar) : Pygopus, Cryptodelma, Delma, Pletholax, Aprasin.
Family AoAMiDiE : Chelosania, Amphibolurus, Tympanooryptis, Diporo-
phora, Chlamydosaurus, Moloch, Oreodeira, Family Scivrin.v : Egorinn.
Trachvsaurus, Hemispha-nodou. Family doubtful : (.)phioi)^ist'ps.
i 1 li
484 ISLAXD LIFE part ii
to a very distinct family (DiscoglossidsB), confined to
the Palsearctic region.
Of tlie fresh-water fishes wo need only say here, that
none belong to peculiar Australian types, but are related
to those of temperate South America or of Asia.
The 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 which can fairly be drawn from
the general facts of New Zealand natural history already
known to us.
Deductions from the Peculiarities of the New Zealand
Fauna. — The total absence (or extreme scarcity) of
mammals in New Zealand obliges us to place its union
with North Australia and New Guinea at a very remote
epoch. We must either go back to a time when Australia
itself had not yet received the ancestral forms of its
present marsupials and monotremes, or we must suppose
that the portion of Australia with which New Zealand
was connected was then itself isolated from the mainland,
and was thus without a mammalian population. We shall
see in our next chapter that there are certain facts in the
distribution of plants, no less than in the geological struc-
ture of the country, which favour the latter view. But
we must on any supposition place the union very far back,
to account for the total want of identity between the
winged birds of New Zealand and those peculiar to
Australia, and a similar want of accordance in the
lizards, the fresh-water fishes, and the more important
insect-groups of the two countries. From what we know
of the long geological duration of the generic types of
these groups we must certainly go back to the earlier
portion of the Tertiary 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 sufficiently near approach
to allow of any important intermigration, even of winged
birds, between them. It seems probable, therefore, that
NEW ZEALAND 485
the Bamptou shoal west of New Caledonia, and Lord
Howe's Island further south, formed the western limits
of that extensive land in which the great wingless birds
and other isolated members of the New Zealand fauna
were developed. Whether this early land extended east-
ward to the Chatham Islands and southward to the
Macquaries Ave have no means of ascertaining, but as the
intervening sea appears to be not more than about l,o(H)
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
Kermadec Islands, and even further 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 (jf
South American and Antarctic 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, is a pure hypothesis, which seems
necessary to explain the occurrence of so many sjiecies
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 allied genera of starlings, the three sjiecies of
parrots of the genus Nestor, and the six distinct rails of
the genus Ocydromus, as well as tlie numerous species in
some of the peculiar New Zealand genera of plants, whicli
seem less likely to have been developed in a single area
than when isolated, and thus preserved from the coiinttM-
acting influence of intercrossing.
In tlie present state of our knowledge; these sreui all
tlie conclusions we can arrive at from a study oi tlie N< w
Zealand fauna; but as we fortunately possess a tolerably
486 ISLAND LIFE part ii
full and accurate 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 how far these con-
clusions a?-e supported by the facts of plant distribution,
and what further indications they afford us of the early
history of these most interesting countries. This inquiry
is of sufficient importance to occupy a separate chapter.
I
CHAPTER XXII
TlIK FI.OKA OF NEW ZKALANJ) : ITS A I'FIMTIKS AM>
PROBABLE ORIGIN
Rektions of the Kcw Zcalaiul Flora to that of Auslialia— (iriinal Fi-atuifs
of tlio Au.stralian Fkua — Tlie Floras of South-eastern and South -wi'stern
Australia— Geological Explanation of the Dillrrenees of these two
Floras— The Origin of the Australian Element in the Xew Zealand Flora
—Tropical Character of the Xew Zealand Flora Explaineil— Species
Connnon to Xew Zealand and Australia mostly Temperate Forms— Why
Easily Dispi'rsed Tlants have often Restricted Ranges— Summary and
Conclusion on the X'ew Zealand Floi'.i.
Although plants have niuaus uf disijersal far L'xeccdiii.u
those possessed by aniinals, yet as a inattei- of faet com-
jiaratively few species are carried for very great distances,
and the tiora 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 an-
almost always better known ; their aftinitios liaxe boon mere
systematically studied; and it may be safely attinned that
no explanation of the origin of the fauna of a country can
be .sound, which does not also explain, or at, least liarmonisc;
with, the distribution and relations of its Kora. Tlic dis-
tribution of the two may be very different, but both shoul.l
be explicable by the same series of geographical changes.
The relations of the Hora of Nc^v Zcnlnnd lo that ot
Australia have long formed an insoluble nn-ina f.-r botan-
488 ISLAND LIFE pakt ii
ists. 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 theorise on the possible
causes of their community of feature frustrated by anom-
alies in distribution, such as I believe no two other similarly
situated countries in the globe present. Everywhere else
I recognise a parallelism or harmony in the main common
features of contiguous floras, which conveys the impression
of their generic affinity, at least, being affected by migi'a-
tion from centres of dispersion in one of them, or in some
adjacent country. In this case it is widely different. Re-
garding 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, &c.,
being absent in New Zealand, with any theory of trans-
oceanic migration that may be adopted to explain the
presence of other Australian plants in New Zealand ; and
it is very difficult to conceive of a time or of conditions
that could explain these anomalies, except by going back
to epochs when the prevalent botanical as well as geograph-
ical 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 sucli broad
features of resemblance, and so many connecting links that
afford irresistible evidence of a close botanical connection,
that I cannot abandon the conviction that these great dif-
ferences will present the least difficulties to wdiatever
theory may explain the whole case." I will now state, as
briefly as possible, what are the facts above referred to as
being of so anomalous a character, and there is little diffi-
culty in doing so, as we have 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 modifications, owing to the later
discoveries which are given in the Handbool- of the New
Zecdand Flora.
Confining ourselves always to flowering plants, wo find
that the flora of New Zealand is a \ery poor one, consider-
in."" the extent of surface, and the favourable conditions of
cHAi'. xxii THE FLOKA OF NEW ZEALAND 489
soil and climate. It consists of 1,085 species (our own
islands possessing about 1,500), but a very large proportion
of these are peculiar, there being no less than 800 eiideniic
species, and thirty-two endemic genera.
Out of the 285 species not peculiar to New Zealand, no
less than 215 are Australian, but a considerable number of
these are also Antarctic, South American, or European ; so
that there are only about 100 Sjm'ics absolutely coniined to
New Zealand and Australia, and, what is inqDortant as in-
dicating a somewhat recent immigration, only some half-
dozen of these belong to genera which are peculiar to the
two countries, and hardly any to the larger and more im-
portant Australian genera. Many, too, are rare species
in both countries and are often alpines.
Far more important are the relations of the genera and
families of the two countries. All the Natural Orders of
New Zealand are found in Australia except three — Coriaria-,
a widely-scattered group found in South Europe, the
Himalayas, and the Andes; Escalloniea', a widely distri-
buted group ; and Chloranthaceie, found in Troi)ical Asia.
Japan, Polynesia, and South America. Out of a total ot
310 New Zealand genera, no less than 248 are Australian,
and sixty of these are almost peculiar to the two countries,
only thirty-two however being absolutely confined to them.^
In the three large orders— Con:il)osita', Orchidea^, and
Gran)inea3, the genera are almost identical in the two
counti'ies, while the species— in the two former especially
— are mostly distinct.
Here then we have apparently a wonderful resemblance
between the New Zealand liora and that of Australia, m-
dicated by more than two-thirds of the non-pecidiarsiJecR-^s,
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 arc in Australia seven great geneia of i)lants. each
containing more than 100 species, all widely spread over
1 lliesc figures arc taken from Mr. G. .Al. Thoiiisoii'.s addn-.s-s "On the
Origin of the New ZeaUuKl Flora,"' Trans. X. Z. Inslilntc, Xl\. (IbSl),
being the latest that 1 can obtain. Thcv dilfur .somewhat Irom iho.sc pivcii
ill the first edition, but not so as to alfect tlie conehisions drawn Irom
them.
490 ISLAND LIFE
the country, and all highly characteristic Australian forms,
— Acacia.. Eucalyptus, Melaleuca, Leucopogon, Stylidium,
Grevillea, and Hakea. These are entirely absent from New-
Zealand, except one sjoecies 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 Zea-
land, five are represented by one or two species, and only
two are fairly represented ; but these two — Drosera and
Helichrysum — are very widespread genera, and might have
readied New Zealand from other countries than Australia.
But this by no means exhausts the differences between
New Zealand and Australia. No less than seven Austral-
ian Natural Orders — Dilleniacea?, Buettneriace3e,Polygalea3,
Tremandrese, Casuarinese, Hsemodoraceae, and Xyrideae are
entirely wanting in New Zealand, and several others which
are excessively abundant and highly characteristic of the
former country are very poorly rej^resented in the latter.
Thus, Leguminoste are extremely abundant in Australia,
where there are over 1,000 species belonging to about 100
genera, many of them altogether peculiar to the country ;
yet in New Zealand this great order is most scantily repre-
sented, there being only five genera and thirteen species ;
and only two of these genera, Swainsonia and Clianthus,
are Australian, and as the latter consists 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.^ Goodeniacea) Avith ten genera and 220
species Australian, has but two species in New Zealand — ■
and one of these is a salt-marsh plant found also in Tas-
mania and in Chile ; and four other large Australian orders
— Rhanniea:;, Myoporinea^ Proteacea^ and Santalacea^, have
^ery few representatives in New Zealand.
We find, then, that the great fact Ave have to explain
and account for is, the undoubted affinity of the New Zea-
^ This accurds with the <^eueial scarcity ol" Ltiguiuinosa' in Oceanic
Islands, due probably to their usually dry and heavy seeds, not adapted to
any of the forms of aerial transmission ; and it would indicate either that
New Zealand was never absolutely united with Australia, or that the union
was at a very remote perio<l when Leguminosce were either not differen-
tiated or comparatively rare.
CHAP. XXII TilK FLORA OF NKW /KALA.NP jyi
hiiid flora to that of Austialia, but an atiinity almost ex-
clusively confined to the least predominant and least
peculiar portion of that flora, leavin«,' the most predominant,
most characteristic, and most widely distributed i>orti<jn
absolutely unrepresented. We must however be careful
nut to exaggerate the amount of Jiffinity with Australia,
apparently implied by the fact that nearly six-sevenths n\'
the New Zealand genera are also Australian, fur. as we
have already stated, a very large number uf these are
European, Antarctic, South American or Polynesian genera,
Avhose presence in the two contiguous areas only indicates
a common origin. About one-eighth, only, are abs(jlutely
confined to Australia and New Zealand (thirty-two genera),
and even of these several are better rejiresented in New
Zealand than in Australia, and may therefore have passed
from the former to the latter. No less tlum 174 <>f th<'
New Zealand genera are tenij^erate South American, many
being also Antarctic or European ; while others again an-
especially tropical or Polynesian : yet undoubtedly a largci-
proportion of the Natural Orders and genera are comnmn
to Australia than to an}^ other country, so that we may say
that the basis of the flora is Australian with a large inter-
mixture of northern and southern temperate forms and
others which have remote world-wide afHnities.
General Features of tltc ^iuslrallan Flora and its Pmlnfhle
Orifjin. — Before proceeding to point out how the
peculiarities of the New Zealand flora may be best
accounted for, it is necessary to consider briefly what are
the main peculiarities of Australian vegetation, from which
so imiDortant a part of that of New Zealand has evidently
been derived.
The actual Australian flora consists of two great
divisions — a temperate and a tropical, the temperate being
again divisible into an eastern and a western portion.
.Vll that is most characteristic of the Australian flcjra
belongs to the temperate division (though these often over-
spread 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 must other i-ouiitries. the
492 ISLAND LIFE
tropical aiDpears to be less rich in species and genera than
the temjoerate region, and what is still more remarkable it
contains fewer peculiar species, and very few peculiar
genera. Although 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 probably not more
than half as many species.^ Nearly 500 of its sj^eciesare
identical with Indian or Malayan plants, or are very close
representatives of them ; while there are more than 200
Indian genera, confined for the most part to the tropical
portion of Australia. The remainder of the tropical flora
consists of a few species and many genera of temperate
^ Sir Joseph Hooker informs lue that the number of tropical Australian
plants discovered within the last twenty j^ears 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 (2,200 tropical to 5,800 temperate species) it seems hardly
possible that a great difierence should not still exist, at all events as
regards species. In Baron von Mueller's latest summary of the Australian
Flora {Second Systematic Census of Australian Plants, 1889), he gives the
total species at 8,839, of which 3,560 occur in A¥est Australia, and 3,251 in
New South AVales. On counting the species common to these two colonies
in fifty pages of the Census taken at random, I find them to be about
one-tenth of the total species in both. This would give the number of
distinct species in these areas as about 6,130, Adding to these the species
peculiar to Victoria and South Australia, Ave shall have a flora of near
6,500 in the temperate parts of Australia. It is true that "West Australia
extends far into the tropics, but an overwhelming majority of the species
have been discovered in the south-western portion of the colony, while the
species that may be exclusively tropical Avill be more than balanced by those
of temperate Queensland, which have not been taken account of, as that
colony is half temperate and half tropical. It thus appears probable that
fidl three fourths of the species of Australian plants occur in the temperate
regions, and are mainly characteristic of it. Sir Joseph Hooker also
doubts the generally greater richness of tropical over temperate floras which
I have taken as almost an axiom. He says: "Taking similar areas to
Australia in the "Western World, e.g., tropical Africa north of 20''S. Lat. as
against temperate Africa and Euro2)e up to 47° — I suspect that the latter
would present more genera and species than the former." This, howcAcr,
appears tome to be hardly a case in point, because Europe is a distinct con-
tinent from Africa and lias had a A'cry diiferent past history, and it is not a
fair comparison to take the tro])ical area in one continent while the temperate
is made up of Avidely separated areas in two continents. A closer })arallel
may perhaps be found in e(|ual areas of Brazil and south temperate Anierica,
or of Mexico and the Southern United States, in both of which cases I
suppose there can be little doubt, that the tropical areas are far the richest.
Temperate South Africa is, no doubt, always c^uoted as richer than an
equal area of 1ro]>ical Africa or pcrhnjis than any part of the world of cc^ual
extent, but this is admitted to be an exce^jtioual case.
CHAP, xxir THE FLORA OF NEW ZKAF^AM) 493
Australia which range over tlie whol(' continent, but tlieae
form only a small portion of the peculiarly Australian genera,
Tliese remarkable facts clearly point to one conclusion --
that the flora of tropical Australia is, comparatively, recent
and derivative. 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, offering an extensive area ready to be covered by
such suitable forms of vegetation as could first reach it,
something like the present condition of things would
inevitably arise. From the north, widespread Indian and
Malay plants would quickly enter, while from the south
the most dominant forms of w^arm-temjDerate Australia, and
such as were best adapted to the tropical climate and arid
soil, w^ould intermingle with them. Even if numerous
islands had occupied the area of Northern Australia for
long periods anterior to the final elevation, very nmch the
same state of things w^ould result.
The existence in North and North-east Australia
of enormous areas covered with Cretaceous and
other Secondary deposits, as well as extensive Tertiary
formations, lends support to the view, that during 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 wliat was retjuired,
in order to bring about the wonderful amount of special-
isation and the high development manifested by the
typical Australian flora. Before proceeding further, how-
ever, let us examine this flora itself, so far as ree:ards its
component parts and probable past history.
The Floras of South-eastern and Sonth-icestern AustraUa.
— The peculiarities presented by the south-eastern and
south-western subdivisions of the flora of temperate
Australia are most interesting and suggestive, and are,
perhaps, unparalleled in any other part of the world.
South-west Australia is far less extensive than the south-
eastern division — less varied in soil and climate, ^^•ith no
lofty mountains, and much sandy desert; yet, strange to
say, it contains an equally rich flora and a far greater
proportion of peculiar species and genera of plants. As Sir
494 ISLAND LIFE part ii
Joseph Hooker remarks : — " What differences there are
in conditions would, judging from analogy with other
countries, favour the idea that South-eastern 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
drier types could extend into South-western Australia.
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 South-western Australia are due
almost wholly to the absence of the numerous European,
Antarctic, and South- American types found in the south-
eastern region, while in purely Australian types
it is far the richer, for while it contains most of those
found in the east it has a large number altoo^ether
peculiar to it ; and Sir Joseph Hooker states that
"there are about 180 genera, out of 600 in South-
western Australia, that are either not found at all in
South-eastern, or that are represented there by a very few
species only, and these 180 genera include nearly 1,100
species."
CJ-eological Explanation of the Differences of tliesc Tioo
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 with detached masses 200 miles to the north and
500 miles to the east — indicates such an extension ; for these
^ Sir Joseph Hooker thinks that later discoveries in the Australian Alps
and. other parts of East and South Australia may have greatly modified or
perhaps reversed the above estimate, and the figures given in the prccM-
ing note indicate that this is so. But still, the small area of South-west
Australia will be, proportionally, far the licher of the two. It is much to
be desired that the enormous mass of facts contained in Jlr. Bentham's
Flora Australiensis and Baron von Mueller's Ccnsun 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 twenty-one years ago.
CHAP. XXII TllK Fl.OllA OK XKW ZKAT.AXD tiC.
oTanitic masses were certainly once buried under piles of
stratified rock, since denuded, and then formed the nucleus
of the old Western Australian continent. Tf ^ve take the
1000-fathomline around the southern ]tart of Australia to
represent the probable extension of this old lanchve sliall see
that it would give a wide additional area soutli of the Great
Australian Bight, and form a continent which, even if the
greater part oftropical Australia were submerged, would be
sufficient for the de^'elopment of a peculiar and abundant
flora. We must also remember that an elevation of GO(M)
feet, added to the vast amount which has been taken a\\ay
by denudation, would change the whole country, including;-
what are now the deserts of the interior, into a iviountnin-
ous and well-watered region.
But while this rich and peculiar flora was in pioccss of
formation, the eastern portion of the continent must either
have been widely separated from the western oi- had
perhaps not yet risen from the ocean. The whole of this
part of the country consists of PaLTOzoic and Secondary
formations with granite and metamorphic rocks, the
Secondary deposits being largely developed on botli sides
of the central range, extending the whole len.g^th of the
continent from Tasmania to Cape York, and constituting
the greater part of the plateau of the Blue :Mountains and
other lofty ranges. During some portion of the Sccouthiry
and Tertiary periods therefore, this side of Australia must
have been almost wholly submerged beneath the ocean ;
and if we suppose that during this time the Avestern part
of the continent was at nearly its maximum extent and
elevation, we shall have a sufficient explanation of the
great difference between the flora of Western and Eastern
Australia, since the latter would only 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 m
Stanford's Compendium of Geography and Travel, volume
Australasia), we shall see good reason to conclude that
the eastern and the western divisions of the country lirst
existed as separate islands, and only became united at a
comparatively recent epoch. This is indicated by an
496 ISLAND LIFE
enormons stretch of Cretaceous and Tertiary formations
extending from the Gulf of Carpentaria completely across
the continent to the mouth of the Murray River. During
the Cretaceous period, therefore, and jDrobably throughout
a considerable portion of the Tertiary epoch,i there must
have been a Avide 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
naiTow belt of land on the east, indicated by the continuous
mass of Secondary and Palaeozoic formations already
referred to which extend uninterruptedly 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 extended across to what is now New Guinea.
At this epoch, then (as shown in the accompanying map),
Australia may, not improbably, have consisted of a very
large and fertile Avestern island, almost or quite extra-
tropical, and extending from the Silurian rocks of the Flin-
ders 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 indicate the existence of one or
more large islands in that direction.
The eastern and the western islands — with which we are
now chiefly concerned — would then differ considerably in
their vegetation and animal life. The western and more
ancient land already possessed, in its main features, the
^ From an examination of the fossil corals of the South-west of Victoria,
Professor P, M. Duncan concludes — "that, at the time of tlie formation of
these deposits the central area of Australia was occupied by sea, having
open water to the north, with reefs in the neighbourhood 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 Oeol,
Sac, 1870.)
CUAl'. XXII
THE FLORA OF NEW ZEA1,.\M
in;
[>eculiar Austnilian Hura, and also the aiiccstral I'uriiis id'
its straugu marsupial fauna, butli ot ^vllicli it liad probably
received at some earlier epoch by a trni|tnrary union witli
the Asiatic continent over what is now llic Java sea.
MAP .SHOWING THi; I'KUIJABI.E CONDITION OK AISTUALIA DIKINU Till: i Ui;T.\<i:<>IS
AND EARLY TERTIARY I'EKIuDS.
I'lie wliitf iiortious rejirosont land ; tlie sh.-nlttl parts .m:i.
Tho cxistiii'' laud of Australia is shown lu outliui-.
Eastern Austialia, (»n the othei" liaiul, possessed only the
rudiments of its existing mixed Hora, derived from tlireo
distinct sources. Some important fragments of tlie typical
Australian vcfrctation had i-caelied it aeros^ thr marine
Iv K
498 ISLAND LIFE part ii
strait, and had spread widely owing to the soil, climate and
general conditions being exactly suited to it : from the
north and north-east a tropica] vegetation of Polynesian
type had occupied suitable areas in the north ; while the
extension southward of the Tasmanian jDeninsula, accom-
panied, i^robably, as now, with lofty mountains, favoured
the immigration of south-temperate forms from whatever
Antarctic lands or islands then existed. This supposition
is strikingly in harmony with what is known of the ancient
flora of this jjortion of Australia. In deposits supposed to
be of Eocene age in New South Wales and Victoria fossil
plants have been found showing a very different vegetation
from that now existing. Along with a few Australian
types — such as Pittosporum, Knightia,and Eucalyj^tus, there
occur birches, alders, oaks, and beeches ; while in Tasmania
in freshwater limestone, apjoarently of Miocene age, are
found willows, alders, birches, oaks, and beeches,^ all except
the latter genus (Fagus) now quite extinct in Australia.^
These temperate forms probably indicate a more oceanic
climate, cooler and moister than at present. The union
with Western Australia and the establishment of an arid
interior by modifying the climate may have led to the ex-
tinction of many of these forms and their replacement by
special Australian types more suited to the new conditions.
At this time the marsupial fauna had not yet reached this
eastern land, which was, however, occupied in the north by
some ancestral struthious birds, which had entered it by
way of New Guinea through some very ancient contiDental
extension, and of whicli 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 Australian Element in the New Zealand
Flora. — We have now brought down the history of
Australia, as deduced from its geological structure and the
main features of its existing and Tertiary flora, to the period
•^ "On the Origin of the Fauna and Flora of New Zealand," by Cajjtaiu
F. W. Hutton, in Annals anclMag. of Nat. Hid. Fifth series, p. 427 (June,
1884).
" To these must now be added the genera Sequoia, Myrica, Aralia, and
Acer, described by Baron von Ettingshausen. (Trans. N.Z. InsiUulc, xix.,
p. 449.)
CHAP, xxii THE FLORA OF NEW ZEALAND 490
when New Zealand was first brought into close connection
with it, by means of a great nurtli-western extension of that
country, which, as already explained in our last chapter, is
so clearly indicated by the form of the sea bottom (See
Map, jj. 471). 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 sedi-
mentary rocks ; w-hile the very small areas occupied by
Jurassic and Cretaceous deposits, imply that much 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
liad already reached tlic tropical and suh-tro'pical 'portions of
the Eastcrih Australian island. It is here that we obtain
the clue to those strange anomalies and contradictions pre-
sented by the New 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 difficuhy
when w^e see that the Australian plants in New Zealand
were acquired, not directly, but, as it were, at second hand,
by union with an island which itself had as yet onl\-
received a portion of its existing flora. And then, further
difficulties were placed in the way of New Zealand re-
ceiving such an adequate representation of that portion
of the flora which had reached East Australia as its
climate and position entitled it to, bytlie fact of the union
being, not with the temperate, but with the tropical and
sub-tropical portions of that island, so that only tlio.se
groups could be acquired which were less exclusively
temperate, and had already established themselves in the
warmer portioi* of their new honie,^
^ Tlie large collection of fossil i>l:iiits from tlic Tcrtiury lu'ds of Nrw
Zealaiul which liave been recently tltsirilu'd l.y IJaron von Kttiiigshaus.-ii
{Trans. N. Z. hid., vol. xxiii., pp. 'J:57- -J51<> , i«rovc lliat a rliiiiii,"' in the
vegetation has occurred similar to that which has taken jdacc in Ea.sl»'rn
Australia, and that the plants of the two countries once resembled each
other more than tiny do now. We have, firs-t, a series of groups now
living in Australia, but which have become extinct in New Zealand, as
500 ISLAND LIFE
It is therefore no matter of surprise, but exactly what we
should expect, that the great mass of j^re-eminently
temperate Australian genera should be absent from New
Zealand, including the whole of such important families
as, Dilleniaceas Tremandrea", Buettneriacai, Polygalese,
Casuarinese and Hsemodoracese ; while others, such as
Kutaceai, Stackhousiese, Rhamneie, Myrtacea^, Proteaceas,
and Santalaceae, are represented by only a few species.
Thus, too, we can explain the absence of all. the peculiar
Australian Leguminosa^ ; for these were still mainly
confined to the great western island, along with the
})eculiar Acacias and Eucalyj^ti, which at a later period
spread over the whole continent. It is equally accordant
with the view we are maintaining, that among the groups
which Sir Joseph Hooker enumerates as "keeping up the
features of extra tropical Australia in its tropical cpiarter,"
several should have reached New Zealand, such as Drosera
some Pittusporete and Myoporineie, with a lew Proteacea?,
Loganiaceaj, and Restiacea3 ; for most of these are not only
found in tropical Australia, but also in the Malayan and
Pacific islands.
Tropical Character of the Neiv Zealand Flora Explained. — ■
In this origin of the New Zealand fauna by a north-western
route from North-eastern Australia, we find also an
explanation of the remarkable nund^er of tropical groups of
plants found there : for though, as Sir Joseph Hooker has
Cassia, Dalbergia, Eucalyptus, Diospyros, Diyandia, Casuariua, aud Fieus ;
and also such nortlieni genera as Acer, Planera, Ulmus, QuereuS; Aliius,
ilyrica, aud Sequoia. All these latter, except Uhaus aud Planera, have
been found also in the Eastern-Austiulian Tertiaries, and we may therefore
consider that at this period the northern temperate element in both lioras
was identical. If this flora entered both countries from the south, and was
really Antarctic, its extinction in New Zealand may have been due to the
submergence of the country to the south, and its elevation and extension
towards the tropics, admitting of the incursion of the large number of
Polynesian and tropical Australian tyi>es now found there ; while the
Australian portion of the same flora may have succumbed at a somewhat later
V)eriod, when the elevation of the Cretaceous and Tertiary sea imited it ^\■ith
Western Australia, and allowed the rich typical Australian flora to overrun
the country. Of course we are assuming that the identification of these
genera is for the most part correct, though almost entirely founded on
leaves only. Fidler knowledge, both of the extinct flora itself and of the
geological age of the several rjpposits, is requisite before any trustworthy
explanation of the phenomena can be arn^•ed at.
•HAP. XXII THK FLORA OF XEAV ZKALAND ',0]
shown, n moist and uniiorni climati- lavours the extensKm
of tropical forms in the tompernto zone, yot sonic moans
nmst be aftorded them for reachincr a temperate island. ( )ii
earefnlly going tlirongh tlie Jl((/if?ho(il\ and comparinn- its
indications with tliose of Bentliam's F/nra ^hfs/m/lru^ii.^, T
find that there are in NewZeahand thiity-eight thoronglilv
tropical genera, tliirty-three of whicli are foniKl iii
Anstralia — mostly in tlie tropic-d j^ortion of it. tliongli a few
are temperate, and tliese may liave readied it tlirougli New
Zealand^ To these we mnst add thirty-two more
genera, which, though cliietly developed in temperate
Anstralia, extend into tlie tiY)])ical or snb-tropical portions
of it, and may well haA'e reached Xoav Zealand hv tlir
same route.
On the other hand we find but tew New Zealand gfiieia
certainly derived from Anstralia wdiich are esjiecially
temperate, and it may be as \vell to give a list of sucli as
^ The following nro tlio tropical geiicvn r-oiiiinon to Xow Zealand an-I
Australia : —
1. MeUcope. Qnecnslaiul, Tacific Islands.
± Eugenia. Eastern and Trojiical Australia, Asia, a)id Aniorira.
?,. Pnsi<iflora. X.S.W. and Queensland, Tropics of Old World and America.
4. Myrsitie. Tro].ical and Temjierate Australia. Tropical and Rub-tropical reu'ions.
5. Sapofa. Australia, Norfolk Islands. Tropics.
G. Cyathodes. Australia and Pacific Islands.
7. Pamonxia. Troi'ical Australia and Asia.
S. Geniostoma. Qufrnsiaud. Polynesia, Asia.
0. Mitrasacme. Trojiical and Temperate Australia. India.
10. Ipomcea. Tropical Australia, Tro]iics.
11. Mazus. Temperate Australia. India, Cliina,
12. Vitex. Tro]iical Australia, Tro]iical and Sub-trcipical.
i:i. Pisonia. Tropical Australia, Trojiical and Sul)-tn;ii('al.
14. Altcrv anther a. Tropical Australia, India, and S. America.
l'>. Tetranthera- Trojiical Australia, Trojiics.
I(}. Santalum. Tro]acal and Suli-tropical Australia, Pacific, ]\ralay Islan<ls.
17. Carumhium. Trojiical and Snb-tro]iical Australia, Pacillc Islan<ls.
18. Elatoftevima. Snb-trnpical Australia, Asia, Pacitic Islands.
10. Pcperomhi. Tro]i!cal and Sul)-ti-o] ical Australia, Tropics.
•20. Piper. Tropical and Sub-tropical Australia. Trnjiics.
21. Dacrydium. Tasmnuia, Malay, and Pacific Islands.
22. Dammara. Tropical Australia, Malay, and Pacific Islanfls.
2n. Dendrobinm. Tro]tical Australia, Eastern Tro]iics.
24. r.oWophylliim. Troj.ical and Sub-tro]iical Australia. Troj'ics.
25. Sareochilus. Tro)>ical and Sub-tropical Au.sfralia, Fiji, and Malay Islands.
2(1. Freycinetia. Tro]iicaI Australia, Trojiical As'a.
27. CordfiUne. Tropical Australia, Pacific Islands.
2«. Bianella. Australia. India, Jladaizascar. Pacific Islands.
20. Cyperua. Australia, Trojiical re^dous mainly.
2.0. Fimhrinfylis. Tro]iical Austialia, Tropical regions.
.''.1. Paspahtm. Trojiical and Sub-tropical "grasses.
.^2. Tsachne. Tropical and Sub-trojiical glasses.
S". Sporohohis. Tropical and Sub-trojiical grasses..
502 ISLAND LIFE
do occur with a few remarks. Tliey are sixteen in number,
as follows : —
1. Pennantia (1 sp.). This geims has a species in Xorfolk Island, indi-
cating perhaps its former extension to the nortli-west.
2. Pomaderris (3 sp.). One species inhabits Victoria and New Zealand,
indicating recent trans-oceanic migration.
3. Quintinia (2 sp.). Thisgenns has winged seeds facilitating migration.
4. Olearia (20 sp. ). Seeds with pappus.
f). Craspedia (2 sp,). Seeds with pappus. Alpine; identical with
Australian species, and therefore of comparatively recent introduc-
tion.
G. C'elmisia (2.5 sp. ). Seeds with pappus. Only three Australian species,
two of which are identical with Xew Zealand forms, probahly
therefore derived from Xew Zealand.
7. Ozothamnus (5 sp. ). Seeds with ])appus.
8. Epacris (4 sp.). JMinute seeds. Some species are sub-tropical, and
they are all found in the northern (warmer) island of Xew Zealand.
0, Archeria (2 sp.). Minute seeds. A species common to E. Australia
and Xew Zealand.
10. Logania (3 sp.). Small seeds. Alpine plants.
11. Hedycarya (1 sp.).
12. Chiloglottis (1 sp. ). ]\Iinute seeds. In Auckland Islands; alpine in
Australia.
13. Prasophyllum (1 sp.). IMinute .seeds. Identical with Australian
species, indi<^ating recent transmission.
14. Orthoceras (1 sp.). Minute seeds. Identical with an Australian
species.
15. Alepyrum (1 sp. ). Alpine, moss-like. An Antarctic type.
16. Dichelachne (3 sp.). Identical with Australian species. An awned
grass.
We thus see that there are special features in most of
these plants that would facilitate transmission across the
sea between temperate Australia and New Zealand, or to
both from some Antarctic island ; and the fact that in
several of them the species are absolutely identical shows
that such transmission has occurred in geologically recent
times.
Bpccics Common to Nev: Zealand and Anstordia Mostly
Temperate Forms. — Let us now take the sjjecics which are
common to New 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 presenting only a
("HAP. xxir THE FLORA OF NEW ZEALAND fwi:^
single species which is confined t(j siib-tropicil Kast
Austraha — a grass (Aiycra arundincicva) only found in a W-w
locaHties on the New Zealand coast.
Now it is clear that the larger portion, if not tlic whole,
of these plants ninst have reached New Zealand from
Australia (or in a few cases Australia from New Zealand),
by transmission across the sea, because we know there has
been no actual land connection during the Tertiary period,
as proved by the absence of all the Australian mammalia,
and almost all the most characteristic Australian 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
Ranunculus, Drosera, Epilobium, Gnaphalium, Senecio.
Convolvulus, Atriplex, Luzula, and many sedges and
grasses, whose exceptionally wide distribution shows that
they possess exceptional powers of dispersal and vigour of
constitution, enabling them not only to reach distant
countries, but also to establish themselves there. Another
set of plants belong to especially Antarctic or south tem-
perate groups, such as Colobantlnis, Aca^na, Gaultheria,
Pernettya, and Muhlenbeckia, and these may in some cases
have reached both Australia and New Zealand from some
now submero^ed Antarctic island. A^ain, about one-fourth
of the whole are alpine plants, and these possess two
advantages as colonisers. Their 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 whidi.
having derived the earlier portion of its flora from the side
of the tropics, would be likely to have its hii^^her mountains
and favourable alpine stations to a great extent unoccu]^ied.
or occupied by plants unable to compete with specially
adapted alpine groups.
501 JSLAND LIFE.
i'AiiT ir
Fully one-third of the exclusively Australo-New Zealand
species belong to the two great orders of* the sedges and
the grasses ; and there can be no doubt tliat tliese liave
great facilities for dispersion in a variety of ways. Their
seeds, often enveloped in chaffy glumes, 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 currents ; and Mr. Darwin's
experiments show that even cultivated oats germinated
after 100 days' immersion in sea-water. Others
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, Avind-fertilised, and are thus independent of any
peculiar insects, which might be wanting in the new
countr3\
Why Easily-Dispersed Plants have often RcsfHctcd Ranges.
— This last consideration throws light on a very curious
point, which has been noted as a difficulty by Sir Joseph
Hooker, that plants Avhich have most clear and decided
powers of dispersal by wind or other means, have not
generally the widest specific range ; and he instances the
small number of Compositse common to New Zealand and
Australia. But in all these cases it will, I think, be found
that although the sjjecies have not a wide range the genera
often have. In New Zealand, for instance, the Compositae
are very abundant, there beino- no less than 1G7 species,
almost all belonging to Australian genera, yet only about
one-sixteenth of tlie whole are identical in the two
countries. The explanation of this is not difficult. Owing
to their great powers of dispersal, the Australian Composita?
reached New Zealand at a very remote epoch, and such as
were adapted to the climate and the means of fertilisation
established themselves ; but being highly organised plants
with great flexibility of organisation, they soon became
modified in accordance with the new conditions, producing
many special forms in different localities ; and these, spread-
ing widely, soon took possession of all suitable stations.
Henceforth immigrants from Australia had to compete
ciiAi'. XXII TiiK j"loi:a of xi:\v /i:ai-ani) .-.d.-.
with these indigenous and wcll-(st;il>lislM(l j.lani.-. .nid ..nlv
in a few eases were able to obtain a ibotin*;-; w Ik -nee It
arises tliat we liave many Australian tyjics. l)ut f.-w
Austraban speeies, in New Zealand, and Ix.tli plirnnnicna
are directly traceable to the combination ot^rcat jk.wcis «.f
(bspersal with a high degree of ada])tabi]ifv. Ivxactlv tbc
same thmg occurs Avith the still nmic lijolilv specialised
(^rchidene. Thest> are not proportionally so numerous in
New Zealand (thirty-eight sjiec^ies;, and lliis is no doubl
due to the fact that so many of them reipiire insect -
fertilisation often by a particular family oi- genus (wlw-rcas
almost any insect will fertilise Composited), and insects (»]'
all orders are remarkably scarce in New Zealand.^ This
would at once prevent the establishment of many of the
orchids which may have reached the islands, while those
which did find suitable fertilisers and other favourable con-
ditions would soon become modified into new species. It
is thus quite intelligible wdiy 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 specialised group — the Scroplndaiinea —
abounds in New^ Zealand, wdiere 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 dispersal great, as shown by several
European genera — Veronica, Euphrasia. an<l Liniosella.
being found in the southern hemisphere.
Looking at the whole series of these Australo-New
Zealand plants, we find the most highly special ise(l
groups — Compositae, Scrophularinea% Orchidea' — witl
small proportion of identical species (one-thirteenth t
twentieth), the less highly specialised — Ranunculacea-.
Onagi'aria' and Ericea — with a higher pn^portion (onc^-
ninth to one-sixth), and the least specialisecl — .luncea-.
^ Insects are tolevalily almiidaiit in llic open niountiiiii ri\i:ioiis, l)Ut vitv
searee iiitlie forests, Mr. Moyriek says that tliosc arc "straiifjely <l('ruMi'nt
in insects, the same species occnrrin.c' llironijlinnt the islamls :" an<l Mr.
Paseoe remarked that "the forests of Xew Zealand were tlie jnost harren
eountrv, entomolofrically, lie had ever visited." I'ror. E,tt. Soc, ISS.S. p.
xxix. )
I a
o one
506 ISLAXD LIFE
Cyperacese and Gramlnese — 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 AustraHa and confined to
them ; and the marked correspondence they show between
liigh speciaUsation and want of specific identity, while the
fjcncric identity is in all cases ap23roximately equal, points
to the conclusion that the means of diffusion are, in almost
all plants ample, Avhen long periods of time are concerned,
and that diversities in this respect are not so important
in determining the peculiar character of a derived flora, as
adaptability to varied conditions, great powers of multi-
plication, and inherent vigour 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.
Swumary and Conclusion on the New Zccdctnd Flora. — Con-
fining ourselves strictly to the direct relations between the
plants of New Zealand and of Australia, as I have done in
the preceding discussion, I think I may claim to have
shown that the union between the two countries in the lat-
ter part of the Secondary epoch at a time when Eastern
Australia was widely separated from Western Australia (as
shown by its geological formation 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 Australian both as re-
crards orders and orenera, for it was due either to a direct
land connection or a somewhat close approximation
between the two countries. It shows also why the great
mass of typical Australian forms are unrepresented, for the
Australian flora is typically vystcrn and iem'pcratc, and New
Zealand received its immigrants from the eastern island
which had itself received only a fragment of this flora, and
from the trojncal 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 very large proportion of tropical forms, for Ave see
that it derived the main portion of its flora directly from
the tropics. Again, this hypothesis shows us why, though
CHAP, xxii THE FLORA OF NEW ZEALAND r.o;
the sjjecially Australian grumi in N^w Z.mI.ukI an-
largely tropical or siib-tropical, the specially Aush.-ilian
species are wholly temperate or al])iiic; for tlicsc a?c
comparatively recent arrivals, they must hav(^ nn<'Tat(Ml
across the sea in the temperate zone, nnd these temjx'iatc
and alpine forms are exactly such as would be best a])I(' to
establish themselves in a country already stocked mainly
by tropical forms and their modified descendants. 'J'lii:.
hypothesis further fulfils the conditions implied in Sir
Joseph Hooker's anticipation that — " these great diffei"-
ences (of the floras) will present the least difficulties to
whatever theory may explain the whole case," — Ibr it
shows that these differences are directly due to the historv
and development of the Australian flora itself, while the
resemblances depend upon the most certain cause of all
such broad resemblances — close proximity or actual land
connection.
One objection will undoubtedly be made to the above
theory, — that it does not explain why some species of the
l)rominent Australian genera Acacia, Eucalyptus. ^Melaleuca.
Grevillea, &c., have not reached New Zealand in recent
times along Avith the other temperate forms that have
established themselves. But it is doubtful whether any
detailed explanation of such a negative fact is possilile,
while general explanations sufficient to cover it are nut
wanting. Nothing is more certain than that mimerous
plants never run wild and establish themselves in countries
where they nevertheless grow freely if cultivated ; and tlic
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. The intercourse between
New Zealand and Eurojie has been the means of intro-
ducing a host of common European ]ilants. — more tlian
150 in number, as enumerated at tlie end (if the second
volume of the Handhoo],' ; yet, although the intercourse
with Australia has probably been greater, only two or
three Australian plants have similarly established them-
selves, ^lore remarkable still, Sir Joseph Hooker states :
r,08 ISLAND LIFf^ vai:t ii
'' I nni informed 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 cliaracteristic groups as Acacia
and Eiicalyi:)tus 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 Euro23ean 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 compete with the indigenous flora which was
already well established and better adapted to the con-
ditions of climate and of the organic environment. This
explanation is so perfectly in accordance with a large body
of well-known facts, including that which is known to
every one — how few of our oldest and hardiest 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.
CHAPTER XXIII
OS THE ARCTIC ELEMENT IN SOUTH TE.M I'KKATj: I'l.olIAS
lOuropean Specieb aud Genera of Plants in the Southern Hemi.sphere —
Aggressive Power of the Scandinavian Flora — Means by wliieli Plants
have Migrated from North to South — Xewly moved Soil as Allbrdiiig
Temporary Stations to Migrating Plants — Elevation and Depression of
the Snow-line as Aiding the Migration of Plants — Clianges of Climate
Favourable to Migration — The Migration irom Xorth to Soutli has been
long going on — Geological Changes as Aiding Migration — Proofs of
Migration l)y way of the Andes — Proofs of ^ligration by way of th<-
Himalaj'as and Southern Asia — Proofs of ^ligratioii Ity way of thi-
African Highlands — Supposed ( "onneetion of South Africa and Australia
— The Endemic Genera of Plants in New Zealand — The Absuiu-r of
Southern Types from the Northern Hemisphere — (.'oiichuling ll»iiiark.>.
on the New Zealand and South Temperate Floras.
We Lave now tu deal with aiiutlier portiou ut' the New
Zealand flora which presents perhaps equal dithculties —
that which appears to have been derived from remote parts
of the north and south temperate zones; and tliis will lead
us to inquire into the origin <>f tlu' noi-tlicni nr Arctic
element in all the south tem2)erate floras.
More than one-third of the entire numlxr of New
Zealand genera (115) are found also in Eurojie. and rveii
flfty-eight species are identical in these remote parts of
the world. Temperate South America has seveiity-foiir
genera in common with New Zealand, and there are even
eleven species identical in the twd ruuntries, as well as
thirty-two which are close allies or representative sjK'cies.
510 TSLAXD LIFE
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 thirty-
eight species very characteristic of Eurojjo and Northern
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 lands and islands ; and these often have repre-
sentative species in Southern America, Tasmania, and
New Zealand, while others occur only in one or two of
these areas. Many north temjDerate 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 northwards, excejit 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 Avhich I have given but
the barest outline, Sir Joseph Hooker makes the following
suggestive 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 terres-
trial sphere which presents the greatest continuity of land.
In the first place Scandinavian genera, and even species,
reappear everywhere froin Lapland and Iceland to the tops
of the Tasmanian Aljjs, in rapidly diminishing numbers it
is true, but in vigorous development throughout. They
abound on the Alps and Pyrenees, pass on to the Caucasus
and Himalayas, thence they extend along the Khasia
Mountains, and those of the peninsulas of India to those of
Ceylon and the Malayan Archipelago (Java and Borneo),
and after a hiatus of 30° they appear on the Alps of New
South Wales, Victoria, and Tasmania, and beyond these
again on those of New Zealand and the Antarctic Islands,
many of the species remaining unchanged throughout ! It
matters not what the vegetation of the bases and flanks of
these mountains may be ; the northern species may be
THAI', xxiii ARCTir PLANTS IN NEW ZEALAND r.ll
associated with alpiiiu forms of Germanic, Siberian, Oriental.
Chinese, American, Mahiyan, and finally Australian, and
Antarctic types ; but whereas these are all, mure (jr less,
local assemblages, the Scandinavian asserts his i)rL'rogativc
of ubi([uity from Britain to beyond its antip(jdes." ^
It is impossible to place the main facts more forcibly
before the reader than in the above striking passage. It
shows clearly that this portion of the New Zealand flora is
due to wide-spread causes which have acted with even
greater effect in other 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, therefore, the facts as given
by Sir Josej^h Hooker in the works already referred to,
I shall discuss the whole question broadly, and shall
endeavour to point out the general laws and subordinate
causes that, in my opinion, have been at work in bringing
about the anomalous phenomena of distribution lie lias
done so much to make known and to elucidate.
Ag(jrc8sivc Poiucr of the Scandinavian Flora. — The first
important fact bearing upon this question is the wonderful
aggressive and colonising power of the Scandinavian flora,
as shown by the way in which it establishes itself in any
tem])erate country to which it may gain access. About loO
species have thus established 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 we accept Mr. ])ar\vin's
explanation of this power as due to development in the
most extensive land area of the globe where competition
has been most severe and long-continued, the fact of the
existence of this power remains, and we can see how imi)ort-
ant an agent it must be in the formation of the floras of
any lands to which these aggressive plants lia\ e been able
to gain access.
But not only are these ])lants pre-eminently capable of
holding their own in any temperate country in tLie world,
but they also have exceptional powers of migration and dis-
* IntroUiiutuiy Jlssay Ua (he Flora of ^LuaLraUu^ p. IJU.
612 ISLAND LIFE
persal 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 flowering plants are identical with European
species. These islands are more than 800 miles from
Europe, and, as we have already seen in Chapter XII.,
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 1,000-fathom Hne
would very little reduce the distance. Now it is a most
interesting and suggestive fact that more than half the
European genera which 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 exaggerated, 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 tln-ough 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
nietliods ; while some may have been carried by aquatic
birds, to whose feathers many seeds have the power of
attaching themselves, and some even in the stomachs of
fruit or seed eating birds. 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 ac-
counting for the migration of animals 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 com-
mand leads us to believe have actually occurred, and
especially of tlie former existence of intermediate islands,
so often indicated by shoals in the midst of the deepest
oceans.
Means hy irJiidt Fhtiits liacc miy rated from Nortlt 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, where-
ever mountain-chains offer suitable stations at moderate
^ Hooker, On- the Flora of Aiistmlvi, p. 9o.— H. C. Watson, iu Godman's
Azores^ pp. 278- 28 6.
CHAP, xxiii ARCTIC PLANTS IN NEW ZEALAND r,l3
intervals on wliicli they might temporarily establish them-
selves. 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 dchris of torrents, and the moraines deposited
by glaciers, afford numerous unoccupied stati(jns on which
wind-borne seeds have a good chance of germinating. It is
a well-known fact that fresh surfaces of soil or rock, such
as are jDresented by railway cuttings and embankments,
often produce j^lants strange to the locality, which survive
for a few years, and then disappear as the normal veg3':a-
tion gains strength and permanence.^ But such a surface
^ As this is a point of great interest in its bearing on tlic dispersal of
plants by means of mountain ranges, I have endeavouicd to obtain a few
illustrative facts : —
1. Mr. William Mitten, of Hurstpierpoint, Sussex, informs me that wh2n
the London and Brighton railway was in progress in his neighbourhood,
Melilotus vnhjaris made its appearance on the banks, reiaained for several
years, and then altogether disappeared. Another case is that oi Dlplutaxia
•murnhs, which formerly occurred only near the sea-coast of Sussex, and at
Lewes ; but since the railway 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 tliick crop of
a plant locally known as fire-weed — a species of Senccio, i)robably S. A>is-
trtUis. It never grows except Avhere the lire has gone over the ground,
and is unknown except in such places. My correspondent adds : — "Tliis
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 cam])ed, and the fire had burnt tlie fallen logs, &c., tliero
was a line crop of 'lire-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 favour the germination of a particular plant, whose seeds
arc easily carried by the wind, and it is not dillicult to sec how this
])eculiavity might favour the disi)er.sal of the species for enormous distances,
by enabling it temporarily to grow and jiroduce seeds on burnt .'<pots.
3. In answer to an inquiry on this subject, Mr. II. C. Watson has been
kind enough to send me a detailed account of the ])rogress of vegetation
on tlie railway banks and cuttings about Thames Ditton. Tliis 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 rcxson to
doubt 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 recollect) and renewed itself either two or throe years, namely, Isatis
tindoria — a species usually supposed to be one of our introduced, but
pretty well naturalised, plants. The nearest stati< ns then or since known
to me for this hatU arc on chalk about Guildfnr I. twenty mihM distant.
L L
514 ISLAND LIFE part ii
will, in the meantime, have acted as a fresh centre of dis-
persal ; and thus a plant might pass on step by step, by means
of stations temporarily occupied, till it reached a district
There were two or three plants of it at first, 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 Barharca precox, oue 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
Pctrosclinum scgctum 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 Linaria 2yurpurca, not
strictly 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 lias remained there several years and grown into a
vigorous specimen. Two or three smaller examples are now seen by it,
doubtless sprung from some of the hundreds or thousands of seeds shed
by the original one plant. The species is not included in Salmon and
Brewer's Flora of Surrey.
"The main line of the railway has introduced into Ditton parish the
perennial Arahis hirmta, 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 authors of the flora of the county, does it
occur. Some years after tlie railway was made a single root of this
Arahis was observed in the brickwork of an arch by which the railway is
carried over a public road. A year or two afterwards there were three or
four plants. In some later year I laid some of the ripened seed-pods
between the bricks in places where the mortar had partly crumbled out,
Xow there are several scores of specimens in the brickwork of the arch.
It is presumable that the first seed may have been brought from Guildford.
But how could it get on to the perpendicular face of the brickwork 1
•' The Bee Orchis {Ophrys apifcra), 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 years back to se'e
about a hundred examples of it in flower in one clayey field either on the
outskirts of Thames Ditton or just within the limits of the adjoining
parish of Cobham. I had crossed this same field in a former year without
observing the Ophrys there. And on finding it in the one field I closely
searched the surrounding fields and copses, without finding it anywhere
else. Gradually the plants became fewer and fewer in that one field,
and some six or eight years after its first discovery there the species had
quite disappeared 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 me with some
information on the temporary vegetation of the banks and cuttings on the
railway from Yarmouth to Caistor in Xorfolk, where it passes over exten-
sive sandy Denes with a sparse vegetation. The first year after the
railway was made the banks produced abundance of (Enothera odoraLa
CHAP. XXIII ARCTIC PLANTS IX XKW Z F.ALA XD 515
where, the general conditions being more favourable, it
was able to establish itself as a permanent member
of the flora. Such, genernlly speaking, was probably tlu*
process by which the Scandinavian flora has made its way
to the southern hemisi^here; but it could hardly have done
so to any important extent w^ithout the aid of those power-
ful 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 soutli
across the w^hole width of the tropics referred to by Sii-
Joseph Hooker. Those causes were, the repeated -changes
and Dclphinktni Jjacis (the latter only known thiity niilos oil" in coiii-
fiekls in Cambridgeshire), \\\x\i At iiple:c'pc(tida^\\(\. A. dcltoiika. Gradually
the native sand plants — Carices, C4rasses, Galium rcrnm, Lc, cstaMishcd
themselves, and year by year covered more ground till the new introduc-
tions almost com])letely disappeared. The same phenomenon was observed
in Cambridgeshire between Chesterton and Xewmarket, where, th<; soil
being ditferent, btcllaria media and other annuals appeared in large patches :
but these soon gave way to a permanent vegetation of grasses, composites,
&c,, so that in the third year no SIch.aria was to be seen.
5. Mr. T. Kiik (writing in 1878) states that — ''in Auckland, where a
dense sward of grass is soon formed, single specimens of the European milk
lih.i'&ilc {Carduus mariamiii^ have been known for tlie past fifteen years;
but although they seeded freely, the seeds had no opportunity of germinat-
ing, so that the thistle did not spread. A remarkable exception to this
rule occurred during the formation of the Onehunga railway, where a few
seeds fell on disturbed soil, grew np and llowered. The railway work.^
being suspended, the plant increased rapidly, and spread wherever it could
find disturbed soil."
Again: — " The fiddle-dock (i^^tmtf.^• ^t?c/ic?') occurs in great abundance
on the formation of new streets, &c,, but soon becomes comnarativcly rare.
It seems probable that it was one of the earliest jdants naturalised here,
but that it partially died out, its buried seeds retaining their vitality."
McdicfKjo satira and ylpiuvi grarcolcns, are also noted as escapes from
cultivation which maintain themselves for a time ])Ut soon die out.'
The preceding examples of the tiuiporanj estai>iishmcnt of jplants on
newly exposed soil, often at considerable distances from the localities they
usually inhnbit, might, no doubt, by further inquiry ]>e greatly multij)lied :
but, unfortunately, the phenomenon hns received little attention, and ia
not even referred to in the elaborate work of Do Candollo {'notjraphic
Bolanique Jlaisouver) in which almost every other aspect of the dispei-sion
and distribution of plants is fully discussed. Lnough has been advancctl,
however, to show tliat it is of constant occurrence, and from the point of
view here advocated it becomes of great importance in explaining ll--
almost world-wide distribution of many common plants of the uortl>
temperate zone.
' Transactions of the ^^cw Zealand InyJUnte, Vol. X. p. 36<
I. L '1
516 ISLAND LIFE part ii
of climate which, during all geological time, appear to have
occurred in both hemispheres, culminating at rare intervals
in glacial epochs, and which have been shown to depend
upon changes ef excentricity 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
how such changes would act in favouring the dispersal of
plants.
Ekuition and Depression of the ^inovj Line as Aiding the
Migration of Plants. — We have endeavoured to show (in an
earlier portion of this volume) that wherever geographical
or j)hysical conditions were such as to produce any
considerable amount of perpetual snow, this would be
increased whenever a high degree of excentricity concurred
with winter in aphelion, and diminished during the
opposite phase. On all mountain ranges, therefore, which
reached above the snow-line, there would be 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
accumulation of snow as to produce great glaciers 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 j^erpetual snow there
would be a corresponding depression of the alpine and
sub-alpine zones suitable for the growth of an arctic and
temperate vegetation, and, what is perhaps more important,
the depression Avould necessarily produce a great extension
of the area of these zones on all high mountains, because
as we descend the average slopes become less abrupt, —
thus affording a number of new stations suitable for such
temperate plants as might first reach them. But just
r.bove and below the snow-line is the area of most
powerful disintegration and denudation, from the alternate
action of frost and sun, of ice and water ; and thus the
more extended area would be subject to the constant
occurrence of land-sHps, berg-falls, and floods, with their
C1IAI-. xxiii ARCTIC PLANTS IX XEW ZEALAND 517
accompanying accumulations of dtih'is and of alluvial soil,
affording innumerable stations in -svliich solitary ^vind-
borne seeds might germinate and temporarily establish
themselves.
This lowering and rising of the snow-line cacli 10,5Ui»
years during periods of high excentricity, would occur in
the northern and southern hemisi)hores alternately; and
where there were high mountains within the tropics the
two would probably overlap each other, so that tlio
northern depression would make itself felt in a slii^ht
degree even across the equator some way into the southern
hemisphere, and vice versd ; and even if the dit^erence of
the height of perpetual snow at the two extremes did not
average more than a few hundred feet, this would bc'
amply sufficient to supply the new and unoccupied
stations needful to facilitate the migration of plants. Ti
is well known that all great mountain ranges have
undergone such fluctuations, as proved by ice-marks bel<»A\
the present level of snow and ice.
But the differences of temperature in the two hemi-
spheres caused by the sun being in 2)crihcIio/i 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 geographiceal conditions wore such as to fii\()ur
the production of glaciation in any area these elU-cts would
become more powerful, and would further aid in thr
dispersal of the seeds of plants.
Changes of Climate Favourable to Migratioa. — 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 favouring 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 liigli
excentricity which produced an extensive glnoiation in
the northern hemisphere and local glaciations in the
southern, these risings and lowerings of the snow-line on
all mountain ranges woidd have been at n maximum. :;nd
518 ISLAND LIFE paiix ii
would have been increased by the deiDression 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 i^roduced the same effect as a general 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 dispersal of all wind-
borne seeds as well as of those carried in the iDlumage or
in the stomachs of birds, since we have seen, by the cases
of the Azores and Bermuda, how vastly the migratory
powers of birds are increased by a stormy atmosphere.
Migration from North to South has been long going on. —
Now, if each phase of colder and warmer mountain-climate
— each alternate 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 hemisphere 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
only ; but we find a whole series of northern types
evidently of varying degrees of antiquity, while even some
genera characteristic of the southern hemisphere appear
to have been originally derived from Europe. Thus
Eucalyptus and Metrosideros have been determined by
Dr. Ettingshausen from their fruits in the Eocene beds of
Sheppey, while Pimelea, Leptomeria and four genera of
ProteacCcE have been recognised by Professor Heer in the
Miocene of Switzerland ; and the former writer has detected
fifty-five Australian forms in the Eocene plant beds of
Hiiring (? Belgium).^ Then we have such peculiar genera
^ Sir Joseph Hooker informs me that he considers these identifications
worthless, and Mr. Bentham has also written very stroni^ly against the
value of similar identifications by Heer and linger. Giving due weight to
the opinions of these eminent botanists wc must admit that Australian
genera have not yet been dcmomtmted to have existed in Europe during
the Tertiary period ; but, on the other hand, the evidence that they did so
appears to have some weight, on account of the improbability that the
numerous resemblances to Australian phants which have been noticed bv
cjrAP. XXIII ARCTIC PLANTS IN NEW ZEALAND 519
as Pacliycliladon and Notothlaspi of New Zealand said to
have affinities with Arctic j^lants, while Stilbocarpa —
another peculiar New Zealand genus — has its nearest
;dlies in the Himalayan and Chinese Aralias. Following
these are a whole host of very distinct species of northern
genera which may date back to any part of the Tertiary
period, and which occur in every south temperate land.
Then we have closely allied representative species of
European or Arctic 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 terminated, rendered it an
agent of sufficient power to have brought about this result.
Here, then, we have that constant or constantly
recurrent process 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 phenomenon of the
species and genera of European and even of Arctic plants
being represented abundantly in South America, Australia,
and New Zealand, thus adds another to the long series of
phenomena which are rendered intelligible by frequent
alternations of warmer and colder climates in eitlier
hemisphere, culminating, at long intervals and in favour-
able 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 periods included in the duration of the
species and genera of plants. A considerable number ot
dilferent observers should all be illusory ; while the well established fact
of the former wide distribution of many tropical or now restricted typos ot
plants and animals, so frcipiently illustrated in the i^resent volume, removes
the antecedent improbability which is supposed to attach to such identifi-
cations. I am myself the more inclined to accept tiicm, because, accordin.u'
to the views here advocated, such miptrations must have taken place at
remote as well as at recent ci»ochs ; and the preservation of some ot thoso
ty])es in Australia while they have become extinct in Europe, is exactly
paralleled by numerous facts in the distribution of animals which have
been already referred to in Chapter XIX., and olsewhcro in \\\u voluim\
and also repeatedly in my larger work.
520 ISLAND LIFE paut ii
tlie jDlants of the Miocene period of Europe were so much
like existing sj)ecies that although they have generally re-
ceived 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 sub-aerial
denudation, 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 elevated. Ancient volcanoes, too, have
been destroyed by denudation, 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 Guiana and Brazil,
for example, must have been far more lofty before the
sedimentary covering was denuded from their granitic
bosses and metamorphic peaks, and may have aided the
southern migration of plants before the final elevation of
the Andes. And if Africa presents us w^ith an example of
a continent of vast antiquity, we may be sure that its
gTeat central plateaux once bore far loftier mountain
ranges before they were reduced to their present condition
by long ages of denudation.
Proofs of Migration hy Way of the Andes. — We are now
prepared to apjDly the principles above laid down to the
explanation of the character and affinities of the various
portions of the north temperate flora in the southern
hemisphere, and especially in Australia and New Zealand.
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
^ Out of forty-two genera from the Eocene of Sheppey eRuinerated
by Dr. Ettingshausen in the Geological Magazine for January ISSO, only
two or three appear to be extinct, while there is a most extraordinaiy inter-
mixture of tropical and temperate forms — Musa, Xipa, and Victoria, with
Corjl.is, Prunus, Acer, kc. The rich ]\Iiocene flora of Switzerland,
described by Professor Heer, presents a still larger proportion of living
genera.
CHAP, xxiii ARCTIC PLAXTS IN NEW ZEALAND 5i:l
a distaDce of about 300 miles occupied by rugged forest-
clad hills, between the lofty peaks of Veragua and the
northern extremity of the Andes of New Grenada. Such
distances are, as we have already seen, no barrier t<) the
diffusion of plants; and we should accordingly expect that
this great continuous mountain-chain has formed the niost
effective agent in aiding the southward migration of tlie
Arctic and north temperate vegetation. We do find, in
fact, not only that a large number of northern genera and
many species are scattered all along this line of route, but
that at the end of the long journey, in Southern Chile and
Fuegia, they have established themselves in such numbers
as to form an important part of the flora of those countries.
From the lists given in the works already referred to, it
appears that there are between sixty and seventy northern
genera in Fuegia and Southern Chile, while about forty of
the species are absolutely identical with those of Euro})0
and the Arctic regions. Considering how comparatiwly
little the mountains of South Temperate America are yet
known, this is a very remarkable result, and it proves
that the transmission of species must have gone on up to
comparatively recent times. Yet, as only a few of tliese
species are now found along the line of migration, we see
that they only occupied such stations temporarily ; and wo
may connect their disappearance with the passing away of
the last glacial period which, by raising the snow-line,
reduced the area on which alone they could exist, and
exiDosed them to the competition of indigenous plants from
the belt of country immediately below them.
Now, just as these numerous species and genera have
undoubtedly passed along the great American range of
mountains, although only now found at its two extremes,
so others have doubtless passed on further; and^ have
found more suitable stations or less severe competition in
the Antarctic continent and islands, in New Zealand, in
Tasmania, and even in Australia itself. The route by
which they may have reached these countries is easily
marked out. Immediately south of Cape liorn, at a
distance of only 500 miles, are the Si.utli Shetland Islands
and Graham's Land, whence the Antarctic continent or a
522 ISLAND LIFE
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 southern outlier of the New Zealand
group ; and the Macquarie Islands are about the same
distance from the 1,000-fathom line at a point 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 w^e 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, w^e may further assume, that
what we know occuiTed wdthin 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 con-
siderable amount of vegetation.^ During such periods
there would be a stead}' migration of plants from all
southern circumpolar countries to people the comparatively
unoccupied continent, and the southern extremity of
America being considerably the nearest, and also being the
best stocked with those northern types wdiich have such
great powers of migration and colonisation, 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 Chile and Fuegia and transmitting them in all
directions from the central Antarctic land may have been
^ Tlie recent discovery by Lieutenant Jensen 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 destitute of vegetation,
although its climate and physical condition are far less favourable than
those of the Arctic lands. (Sec Kahi.rr, Vol, XXI. p. 345.)
viiAv. xxiii ARCTIC TLAXTS IN NEW ZEALAND 524
repeated several times during the Tertiary jieriudjWe have
no difficulty iu understanding the general community
between the European and Antarctic plants found in all
south temperate lands. Kerguelen's Land and Thf Crozets
are witliin about the same distance from the Antarctic
(continent as New Zealand and Tasmania, and Ave need not
tlierefore be surprised at finding in eacli of these islands
some Fuegian species which have not reached the others.
Of course, there will remain difficulties of detail, as there
always must remain, so long as our knowledge of the past
changes of the earth's surface and the history of the particu-
lar plants concerned is so imperfect. Sir Joseph Hookei-
notes, for example, the curious fact that several Composite.*
common to three such remote localities as the Auckland
Islands, Fuegia, and Kerguelen's Land, have no pappus or
seed-down, while such as have pappus are in no case com-
mon even to two of tliese islands. Without knowing the
exact history and distribution 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.
Proofs of Migraiion by way of the Hiinalayas and South-
ern 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, Ave cannot account for
the Avhole of it by this means, because Australia itself con-
tains a host of European and Asiatic genera of Avhich avc
find no trace in NeAv Zealand or South America, or any
other Antarctic land. We find, in fact, in Australia tAvo
distinct sets of European plants. First Ave have a number
of species identical Avitli those of Northern Europe or Asia
(of the most characteristic of Avhich — thirty-eight in
number — Sir Joseph Hooker gives a list) ; and in the sec-
ond place a series of European genera usually of a somc-
Avhat more southern character, mostly represented by
A'^ery distinct species, and all absent from Ncav Zealand ;
such as Clematis, Papaver, Cleome, Polygala, Lavatera.
Ajuga, &c. NoAV of the first set — the North European
species — about three-fourths occm* in some parts of America,
524 ISLAND LIFE part ii
and about half in South Temperate America or New Zea-
land ; 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-Earopean genera,
however, and many others characteristic of the South Euro-
pean or the Himalayan flora, have probably reached
.Vustralia 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 existed, sufficient 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, in-
dicates the route of this immigration, and sufficiently ex-
plains 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 the peculiar genera
confined to these two countries ; but most of them are of
later date, and have thus remained in Australia only.
Proofs of Mignttion hi/ v:ay of the African Higlilands.—
It is owing to this twofold current of vegetation flowing
into Australia by widely different routes that we have in
this distant land a better re|)resentation of the European
flora, both as regards 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 individual species — that is
not fairly accounted for by such an origin. It further
receives support from the case of South Africa, which also
contains a large and important representation of the north-
ern 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 tem-
perate plants in South Africa, none of which occur in Aus-
tralia ; while very few of the species, so characteristic of
Australia, New Zealand, and Fuegia, are found there. It
CHAP, xxiii ARCTIC PLANTS IX NEW ZEALAND 525
is clear, therefore, that South Africa has received its Euro-
pean plants by the cHrect route through the Ahyssiniau
highlands ar.d the lofty equatorial mountains, and mostly
at a distant period when the conditions for migration were
somewhat more favourable than they are now. Tlic 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 Africn
has more very northern European f/cncra than Australia,
while Australia has more identical sj^cciVs and a better rep-
resentation on the -svhole of the 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 distance 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, is all quite in harmony
with the facts of distribution of the northern i\ora above
referred to.
Sitpposed Connection of South Africa and Australia.—
There remains, however, the small amount of direct aflinity
between the vegetation of South Africa and that of Austra-
lia, New Zealand, and Temperate South America, consisting
in all of fifteen genera, five of wdiich are confined to
Australia and South Africa, while several natural orders
are better represented in these two countries than in any
other part of the world. This resemblance has been sup-
posed to imply some former land-connection of all the great
southern lands, but it appears to me that any such suppo-
sition is wholly unnecessary. The ditifercnces between the
faunas and floras of these countries are too great and too
radical to render it possible that any such connection
should have existed excej^t at a very remote period. But
if we have to go back so far for an explanation, a much
simpler one presents itself, and one more in accordance
with what we have learnt of the general permanence of
deep oceans and the great changes tliat have taken place
526 ISLAXD LIFE part ii
in the distribution of all forms of life. Just as we exjolain
the presence of marsupials in Australia and America and
of Centetid^e in Madagascar and the Antilles, by the pre-
servation in these localities of remnants of once wide-spread
types, so we should jDrefer to consider the few genera com-
mon 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 special-
ised types, and now finding a refuge in these two widely
separated southern lands. It is suggestive of such an ex-
planation that these genera are either of very ancient
groups — as Conifers and Cycads — or plants of low organ-
isation as the Restiacea^ — or of world-wide distribution, as
MelanthaceEe.
Tlic Endemic Genera of Plants in Neio Zealand. — Returning
now to the New Zealand flora, with which we are more
especially concerned, there only remains to be considered
the peculiar or endemic genera which characterise it.
These are thirty-two in number, and are mostly very
isolated. A few have affinities 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 Leguminosse, Saxifragese,
Compositae, Orchidese, &c. AYe must evidently trace back
these peculiar forms to the earliest immigrants, 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
ample time for the changes in the general distribution of
plants, and for those due to isolation and modification under
1 Dr. Hector notes the occurrence of the genus Dammara in Triassic
deposits, while in the Jurassic period New Zealand possessed the genera
Palccozamia, Olcandriiim, Ahihopteris, Campto'ptcris, Cycculitcs, Echino-
strohvs, kc, all Indian forms of tlie same age. Neocomian beds contain
a true dicotyledonous leaf with Dimmara and Araiicaria. The Cretaceous
deposits have produced a rich flora of dicotyledonous plants, many of
which are of the same genera as the existing flora ; while the Miocene and
other Tertiary deposits produce plants almost identical with those now
inhabiting the country, together with many Xorth Temperate genera which
have since become extinct. (See p. 49P, footnote, and Trans. Xrw Zealand
LuiL, Vol. XI. 1879, p. 536.) .: .
cjiAP. XXIII ARCTIC I'LAXTS IX NKW ZKALAXI) .VJ7
the influence of changed conditions, which are manifested
by the extreme peculiarity of many of these inten'StinK
endemic forms.
The Absence of So^Uhcrn Types from the Northern Hcmi-
sjjJiere. — We have now only to notice the singuLar want of
reciprocity 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, whether developed in tin-
Antarctic lands. New Zealand, South America, or Soutli
Africa. The furthest northern outliers of the southern
flora are a few^ genera of Antarctic type on the Bornean
AljDs ; the genus Accena which has a species in California ;
two representatives of the Australian flora — Casuariua
and Stylidium, in the peninsula of India; Avhile China
and the Philippines have two strictly Australian genera of
Orchide?e — Microtis and Thelyiuitra, as Avell as a Resti-
aceous genus. Several distinct causes appear to have
combined to jDroduce this curious inability of the southern
flora to make its w^ay into the northern hemisphere. The
primary cause is, no doubt, the totally different distribution
of land in the two hemispheres, so that in the south there
is the minimum of land in the colder parts of the
temperate zone and in the north the maximum. This is
well shown by the fact that on the parallel of Lat. 50° N.
w^e pass over 240° of land or shallow sea, while on the
same parallel of south latitude we have only 4°, where we
cross the southern part of Patagonia. Again the three
most important south temperate land-areas — S(Mith Tem-
perate America, South Africa, and AustraHa — are widely
separated from each other, and have in all probability
always been so ; whereas the wdiole of the north temperate
lands are practically continuous. It follows that, instead of
the enormous northern area, in whicli highly organised and
dominant groups of plants have been developed gifted
with great colonising and aggressive powers, we have in
the south three comparatively small and detached areas, in
which rich floras have been developed witli sprriol adaptn-
52S ISLAND LIFE part ii
tious to soil, climate, and organic environment, but
comparatively impotent and inferior beyond their own
domain.
Another circumstance which makes the contest betv/een
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 extensively 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 accustomed, and are thus often able
to gi'ow and flourish even more A'igorously than in their
native land, the southern plants would find in almost
every j^art of Europe, North America or Northern 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 extended 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, tliat Australian plants are rapidly
sowing themselves and becoming naturalised on the Neilgherrie mountains
in the southern part of the Indian Peninsula, though an exception to the
rule of the inability of Australian plants to become naturalised in the
Northern Hemisphere, is yet quite in harmony with the hypothesis here
advocated. For not only is the climate of the Neilgherries more fixvour-
able to Australian plants than any part of the North Temperate zone, but
the entire Indian Peninsula has existed for unknown ages as an island and
thus possesses the "insular" characteristic of a comparatively poor and
less developed flora and fauna as compared with the truly "continental"
Malayan and Himalayan regions. Australian plants are thus enabled to
compete with those of the Indian Peninsula highlands with a fair chauco
of success,
ciiAr. xxiii AKCTIC PLANTS IX NEW ZKALAND f.-^y
Concluding JRemarJiS on the Last Two Chapters. — Our
inquiry into the external relations and probal)lo 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 hemi-
spheres; and no better or more typical example could
be found of the wide range and great interest of the
study of the geographical distribution of animals and
plants.
The solution wiiich 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 structure of the great Australian continent.
Without this knowledge we should have nothing but a
series of guesses or probabilities 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 a portion of
the Cretaceous and Tertiary periods, could never have been
guessed till it was established by the laborious explorations
of the Australian geologists ; while the hypothesis of a com-
paratively shallow sea, uniting New Zealand by a long route
with tropical Australia, while a iDrofoiuidly deep ocean
always separated it from temperate 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 enabled
to give an adequate explanation of the strange anomalies
in the flora of Australia and its relation to that of New
Zealand.
In the more general explanation i.f the relations of the
various northern and southern floras, I have shown what
an important aid to any such explanation is the theory of
repeated changes of climate, not necessarily of gi'cat
amount, given in Chapters Ylll.and IX. ; while the whole
discussion justifies the importance attached to the tlicory
of the general permanence of continents and oceans, as
demonstrated in Chapter YL, since any rational explana-
tion based upon facts (as oi)posed to mere unsupported
M M
530 ISLAXD LIFE tartii
conjecture) must take such general permanence as a
starting-point. The 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 lirm foundation for the discussion of questions
of distribution and dispersal ; and that by its aid, com-
bined with a clear perception of the wonderful powers
of dispersion and modification in the organic world when
long periods are considered, the most difficult problems
connected with this subject cease to be insoluble.
CHAPTER XXIV
SUMMARY AND COXCLUSION
The Pres'iiit Volume is the Uevelupnient and Aiiiilicciiiun of a Tlicoiy—
Statement of the Biological and Ph3\sical Causes of Dispersal — Inve'sti-
gation of the Facts of Dispersal — of the Means of Dispersal— of Geo-
graphical Changes Affecting Dispersal— of Climatai Changes Atfecting
Dispersal — The Glacial Epoch and its Causes — Alleged Ancient Glacial
Epochs— Warm Polar Climates and tlieir Causes— Conclusions as t*-)
Geological Climates — How far Di (11- rent from those of ^Mr. Croll —
Supposed Limitations of Geological Time— Time Amply SulUciont botli
for Geological and Biological Develo])mont — Insular Faunas and Floras
— The North Atlantic Islands — The Galapagos— St. Helena and tin-
Sandwich I.-lands — Great Britain as a Recent Continental Island —
Borneo and Java — Japan and Formosa — Madagascar as an Ancient
Continental Island — Celebes ami Xew Zealand as Anomalous Islands —
The Flora of Xew Zealand and its Origin — The European Element in the
South Temperate Floras — Concluding Remarks.
The present volume has gone over a very wide tield both
of facts and theories, and it will be well to recall these to
the reader's attention and point out their connection with
each other, in a concluding chapter. I hope to be able to
show that, although at first sight somewhat fragmentary
and disconnected, this work is really tlie development of a
clear and definite theory, and its application to tlie sohition
of a number of biological problems. That tlioory is,
briefly, that the distribution of tlie various species and
groups of living things over the earth's surface, and their
nggregation in definite assemblages in certain areas, is the
y\ M 2
532 ISLAND LIFE
PART II
direct result and outcome of a complex set of causes, which
may be grouped as " biological " and '' physical." The
biological 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 organisms arise
and grow, reach their maximum, and then dwindle 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 faunas and floras — and it was here 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 climate
which have occurred in various parts of the earth, —
because such changes are among the most powerful agents
in causing 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 ofdevelopment of the organic
world ; and both these processes are shown to involve, so
far as we can judge, 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 presented by the floras and faunas of the chief
islands of the globe, which are classified, in accordance
with their pliysical origin, in three groups or classes, each
CHA1-. XXIV SUMMARY AND COXCLUSIOX 588
of which are shown to exhibit certain well-marked biolofrical
leatnrcs.
Having thus shown that the work is a connected whole,
founded 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 sevond chapters, by
means of which this general conception lins been earned
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 species, genera, and families,
and have illustrated the subject by maps showing the
peculiarities of distribution of some well-known 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 " zoological
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" is exhibited by a number of
curious examples ; the origin, gi'owth, and decay of
species and genera are traced, and all tlie interesting
phenomena of isolated groups and discontinuous generic
and specific areas are shown to follow as logical conse-
quences.
The next subject investigated is the means by whicli
the various groups of animals are enabled to overcome the
natural barriers which often seem to limit them to very
restricted areas, how far those bari'iers are themselves
liable to be altered or abolished, and what is 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 important 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 evidence are adduced to prove that the gi*and
features of our globe — the positi<;>n of the great oceans
534 ISLAND LIFE part ii
and the chief land -areas — have remained, on the whole,
unchanged throughout geological time. Our continents
are shown to be built up mainly of " shore-deposits " ; and
even the chalk, \vhich is so often said to be the exact
equivalent of the " giobigerina ooze " now forming in
mid- At] antic, is shown to be a comjDaratively shallow-
water deposit formed in inland seas, or in the immediate
vicinity of land. The general stability of continents has,
however, been accompanied by constant changes of form,
and insular conditions have prevailed over every part in
succession ; and the effect of such changes on the distribu-
tion 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 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 universally admitted,
but the causes which brought it on are matter of dispute.
But unless we can arrive at these causes, as well as at
those which j^roduced the equally well demonstrated mild
climate in the Arctic regions, we shall be cpiite unable to
determine the nature and amount of the changes of
climate which have occurred throughout past ages, and
shall thus be left without a most important clue 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 explanations, and, taking up the
two which alone seem tenable, I endeavour to determine
the true principles of each. While adojiting generally
Mr. Croll's view^s as to the causes of the " glacial epoch,"
I have introduced certain limitations and modifications.
I have pointed out, I believe, more clearly than has
hitherto been done, the very different effects on climate of
water in the liquid and in the solid state : and I have
CHAP. XXIV SUMMARY AXD COXCLUF^IOX 533
showD, by a variety of evidence, that without ]\v^]i land
there can be no permanent snow and ice. From tlicse
facts and principles the very important conclusion is
reached, that the alternate phases of precession — causinor
the winter of each hemisphere to be in (qiliclion and
perihelion each 10,500 years — would produce a complete
change of climate only where a country was ^irr?'^?^//?/
snow-clad ; while, whenever a large area became almost
ivholly buried in snow and ice — as was certainly the case
with Northern Europe and America during the glacial
epoch — then the glacial conditions would be continued
and perhaps even intensified Avhen the sun approached
nearest to the earth in winter, instead of there being at
that time, as Mr. Croll maintains, an almost perpetual
spring. This important result is supported by reference
to the existing differences between the climates of the
northern and southern hemispheres, and by what is known
to have occurred during the last glacial epoch ; and it is
shown to be in complete harmony with tlie geological
evidence as to interglacial 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, uninter-
rupted 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 vegetation
in the highest latitudes yet explored. The geographical
condition of the northern hemisphere at these periods is
then investigated, and it is shown to have been probably
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 calculations
as to the enormous quantity of heat that would thus be
conveyed northwards, it is maintained that the mild
Arctic climates are amj^ly accounted for. With such
favourable geographical conditions, it is shown, that
changes of excentricity and of the phases of ]irecession
would have no other effect tliau to crai«e greater iliiVerences
536 ISLAND LIFE
PART II
of temperature between summer 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 considerable amount of
local glaciation might result. Thus may be ex^Dlained the
presence of enormous ice-borne rocks in Eocene and
Miocene times in Central Europe, while at the very same
period all the surrounding country enjoyed a tropical or
sub-tropical climate.
The general conclusion is thus reached, that geograj)hical
conditions are the essential causes of great changes of
climate, and that the radically different distribution of
land and sea in the northern and southern hemispheres
has generally led to great diversity of climate in the
Arctic and Antarctic regions. The form and arrangement
of the continents is shown to be such as to ftivour the
transfer of warm oceanic currents to the north far in
excess of those wdiich move towards the south, and
whenever these currents had free passage throngh the
northern land-masses to the polar area, a mild climate
must have prevailed over the whole northern hemisiDhere.
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 w^ater from
their interiors, and rendering possible a wide-spread and
intense glacial epoch. But this great climatal change was
actually brought about by the high excentricity which
occurred about 200,000 years ago ; and it is doubtful if a
similar glaciation in equally low latitudes could be jDroduced
by means of any such geographical combinations as
actually occur, without the concurrence of a high excen-
tricity.
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 extent over three-fourths of the
globe. In the Alps and Pyrenees, in the British Isles
and Scandinavia, in Spain and the Atlas, in the Caucasus
fiiAr. XXIV SL'MMAKV AXD CONCLUSION
and the Himalayas, in Eastern North America and west
of the Rocky Mountains, in the Andes of Sc^uth Temperate
America, 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 tlie influence of
hioh excentricity as the cause of this almost imi versa I
glaciation, we must postulate a general elevation of «//
these mountains about the same time, geologically speaking
—for the general similarity in the state of preservation of
the ice-marks and the known activity of denudation as a
destroyino- agent, forbid the idea that they belong tu
widely separated epochs. It has, indeed, been suggested,
that denudation alone has lowered these mountains so much
during the post-tertiary 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 stria\
undisturbed and uneffaced on the slopes and m the
valleys of these same mountains.
The theory of geological climates set forth m this
volume, while founded on Mr. Croll's researches, difters
from all that have yet been made public, m clearly
tracing out the comparative influence of geographical and
astronomical revolutions, showing that, while the tormer
have been the chief, if not the exclusive, causes of the
lono'-continued mild climates of the Arctic 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 hi low latitudes, of wlucli
there is such an abundance of evidence. , • i
The next question discussed is that ot geological
time as bearing on the development of the organic world.
The periods of time usually demanded by geologists have
been very cn-cat, and it was often assumed that there wa.s
no occasion to limit them. But the theory of development
demands far more ; for the earliest fossihferous rocks
53? ISLAND LIFE partii
prove the existence of many and varied forms of life which
require imrecorded ages for their development — ages
probably far longer than those which have elapsed from
that period to the present day. The johysicists, however,
deny that any such indefinitely long periods are available.
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 rotation, 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 sufficient for the long processes of geological chano-e
and organic development. It is therefore important to
inquire Avhether these processes are either of them so
excessively slow as has been supposed, and I devote a
chapter to the inquiry.
Geologists have measured with some accuracy 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
maxiimim thickness of the hioivn sedimentary rocks is taken
to represent the average thickness of all 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 if coincident with the last period of high
excentricity, while the Alpine glaciation of the Miocene
period is assumed to have been caused by the next earlier
phase of very high excentricity. Taking these a^ data, the
CHAP. xxiY SUM:\IARY and COXCLUSIOX 589
proportionate change of the species of mollusca afford,
a means of arriving at the whole lapse of time represented
by the fossiliferous rocks ; and the?e two estimates agreo
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
excentricity have acted as a motive power in hastening on
both geological and biological change. By raising and
lowering tlie 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 modification
of species. The present epoch being a period of very low
excentricity, the earth is in a phase of coxciotional stahility
both physical and organic ; and it is from this period of
exceptional 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 fossiliferous 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 interpre-
tation of the phenomena of distribution, we proceed to the
Second Part of our work— the discussion of a series of
typical Insular Faunas and Floras with a view to explain
the interesting phenomena they present. Taking first two
North Atlantic groups — the Azores and Bermuda — it is
shown how important an agent in the dispersal of most
animals and plants is a stormy atmosphere. Although 900
and 700 miles respectively from the nearest continents,
their productions are very largely identical with those of
Europe and America ; and, what is more important, fresh
arrivals of birds, insects, and plants, are now taking place
almost annually. These islands afford, therefore, test
examples of the great dispersive powers of certain groups
of organisms, and thus serve as a basis on which to found
our explanations of many anomahes of distribution. Passing
540 ISLAND LIFE part ii
on to the Galapagos we have a group less distant from a con-
tinent and of larger area, yet, owing to special conditions, of
which the comparatively stormless equatorial atmosphere is
the most important, exhibiting far more speciality in its pro-
ductions than the more distant Azores. Still, however, its
fauna and flora are as unmistakably derived from the
American continent as those of the Azores are from the
European.
We next take St. Helena and the Sandwich Islands, botli
wonderfully isolated in the midst of vast oceans, and no
longer exhibiting in their productions an exclusive affinity
to one continent. Here we have to recognise the results
of immense antiquity, and of those changes of geography,
of climate, and in the general distribution of organisms
which we know have occurred in former geological epochs,
and wdiose causes and consequences we have discussed in
the first part of our volume. This concludes our review of
the Oceanic Islands.
Coming now to Continental Islands we consider first
those of most recent origin and offering the simj^lest phe-
nomena ; and begin with the British Isles as affording the
best example of very recent and well known Continental
Islands. Reviewing the interesting past history of Britain,
w^e show why it is comparatively poor in species and w^hy
this poverty is still greater in Ireland. By a careful
examination of its fauna and flora it is then shown that the
British Isles are not so completely identical, biologically,
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 outlying islands, such as the Isle of Man, the
Shetland Isles, Lundy Island, and the Isle of Wight, all
possess certain species or varieties not found elsewhere.
Borneo and Java are next taken, as illustrations of tropi-
cal islands wdiich may be not more ancient than Britain,
but which, owing to their much larger area, greater distance
from the continent, 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 prelimi-
ciiAi'. XXIV SUMMARY AND CONCLUSION 541
uary studies we have made enable us to afYord a simpler
and more definite interpretation of tlie peculiar relations
of Java to the continent and its difterences from Borneo
and Sumatra, than was given in my former wijvk (Thr
Geographical Distribution of Animals).
Japan and Formosa are next taken, as examjiles of
islands which are decidedly somewhat more ancient than
those previously considered, and which present a number
of very interesting 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
surrounded 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 — a^
Bourbon, Mauritius, and Rodriguez — are decidedly oceanic.
In order to understand the peculiarities of the Madagascar
fauna we have to consider the past history of the African
and Asiatic continents, which it is shown arc such as to
account for all the main peculiarities of the fauna of these
islands without having recourse to the hypothesis 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 distri-
bution. The origin of the interesting Mascarene wingless
birds is discussed, and the main peculiarities of the
remarkable 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 of the perma-
nence of the great oceans and the comparatively slight
fluctuations of the land area, and by taking account of
established pala^ontological facts.
There remain two other islands — Celebes and New
Zealand — which are classed as *' anomalous," the one because
it is almost impossible to ]>lace it in any of the six
zoological regions, or determine whether it lias ever been
actually joined to a continent— the other because it
542 ISLAND LIFE part ii
combines the characteristics of continental and oceanic
islands.
The peculiarities of the Celebesian fauna have already
been dwelt upon in several previous works, but they are
so remarkable 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 appli-
cation of the general i^rinciples 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 outlying
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 remained 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 surrounding islands by the
ordinary means of dispersal. This sufficiently explains all
the peculiar affinities of its animals, though the peculiar and
distinctive chamders of some of them remain as mysterious
as ever.
New Zealand is shown to be so comjoletely continental in
its geological structure, and its numerous wingless birds so
clearly imply a former connection with some other land
(as do its numerous lizards and its remarkable rejDtile, the
Hatteria), that the total absence of indigenous land-
mammalia was hardly to be expected. Some attention is
therefore given to the curious animal which has been seen
but never captured, and this is shown to be probably
identical with an animal referred to hy 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 Australia was towards the north, and this is found
to agree w^ll with many of the peculiarities of its
fauna.
The flora of New Zealand and that of Australia are
now both so well known, and they present so many
peculiarities, and relations of so anomalous a character,
CHAF. x\-Tv SU.M.MARV AND CONCLUSION 543
as to present in Sir Josej^li Hooker's opinion an almost
insoluble problem. Much additional information on the
physical and geological history of these two countries lias,
however, been obtained since the appearance of Sir Jo.scpli
Hooker's works, and I therefore determined to aj)i)ly t(j
them the same metliod of discussion and treatment whicli
has been usually successful with similar j^roblems in tht^
case of animals. The fact above noted, that New Zealand
was connected with Australia in its northern and tropical
portion only, of itself aftbrds a clue to one portion of the
specialities of the New Zealand flora — the presence
of an unusual number of tropical famiUes 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 clue 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 higldy ]iecuHar
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 jjlants and of
animals, since these existed at that time only in tho
western island, while New Zealand was in connection with
the castcni island alone and with the tropical portion 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 wdder, and it' 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
diflidence I entered upon it, yet it arose so naturally from
the study of the New Zealand and Australian tloras, and
seemed to have so much light thrown upon it by our
preliminary studies as to changes of climate and the causes
which have favoured the distribution of plants, that I felt
my work would be incomplete without a consideration of
544 ISLAND LIFE
it. The subject will be so fresh in the reader's mind that
a comjolete 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 sj^ecial aids
to their migration, and the motive power which has urged
them on.
In this discussion, if nowhere else, will be found a
comiDlete 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. Without the clear and
definite conclusions arrived at by that discussion, 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 v/ide and difficult problem
of the northern element in southern floras.
In concluding a work dealing with subjects which have
occupied 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
comjjlete interdependence of organic and inorganic nature.
Not only does the marvellous structure of each organised
being involve the whole jDast history of the earth, but such
apparently unimportant facts as the presence 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
astronomical revolutions wliicli cause a periodic variation
of terrestrial climates — on the ajDparently fortuitous action
of storms and currents in the conveyance of germs — and
on the endlessly varied actions and reactions of organised
beings on each other. And although these ^'arious 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 recognisable ; and we are
thus encouraged to study more completely every detail and
ciiAr. XXIV SUMMARY AND CON<"LrsK)X
every anomaly in the distribution of living- tilings, in tho
firm conviction that by so (hnng we sliall obtain a fuller
and clearer msight into tlic course of nature. an<l with
increased confidence tliat tlie " niiglity maze" of licing we
see everywhere around us is " not without a plan."
D. H. HILL LIBRARY
INDEX
N N
INDEX
Acacia, wide range of in Australia, ISo
Acacia heterophylla, and Acacia Icoa, 443
Acsena in California, 527
Accipiter haicaii, 314
Achatinellin.T?, average range of, 317
^^gialitis sanctcr-helfticp, 305
Africa, characteristic mammalia of, 416
former isolation of, 41 S
Africa and Madagascar, relations of, 418
early history of, 419
African highlands as aiding the migration
of plants, 524
African reptiles absent from Madagascar,
418
Aggressive power of the Scandinavian flora,
511
Air and water, properties of, in relation to
climate, 131
Alectorcnias pulcherrimus, 429
Allen, Mr. J. A., on variation, 58
Allied species occniiy separate areas, 478
Alpine plants, tlieir advantages as colo-
nisers, 503
Alternations of climate in Switzerland and
North America, 121
Alternations of climate, palffiontological
evidence of, 119
Amazon, limitation of species by, 18
Amblyrhyiichus cristatiix, 279
American genera of reptiles in Madagascar,
417
Amphibia, dispersal of, 7G
of the Seychelles, 432
introduced, of Mauritius, 435
of New Zealand, 483
Amphioxus, 63
Amphisba-'nidae, 28
Amydrus Tristramii, restricted range of, 16
Anas Wyvilliana, 314
Ancient continental islands, 244, ill
Ancient glacial epochs, 169
what evidence of may be expected, 175
Ancient groups in Madagascar, 419
Andersson, N. J., on the flora of the Gala-
pagos, 2S7
Andes, migration of jdants along the, 520
Angrcecum sesquipedale, 440
Animal life, effects of glacial epoch on, 117
Animal life of Formosa, 401
Anoa depressicornis, 450
Antarctic continent as a means tif jdant-
dispersion, 521
Antarctic islands, with perpetual snow, 136
Antelopes, overlapjiing genera of, 20
Antiquity of Hawaiian fauna and flora, 328
of land- shells, 79
of New Zealand, 526
of plants as affecting their dis-
persal, 82
Apera arundinacea, 503
Apium O'l-aveolens in New Zealand, 515
Apteryx, species of, 476
Arabis hirsuta on railway arch, 514
Archaic forms still existing, 229
Arctic and Antarctic regions, contrasts of,
135
Arctic current, effects of a stoppage of,
150
Arctic plants in the southern liemispherc,
509
Arctic regions, mild climates of, Isl
recent interglacial mild period in, 1S2
Arctic warm climates of Secondary an<l
Palicozoic times, 201
Areas of distribution, 13
separate and overlapping, 17, 28
Ascension, former climate and productions
of, 303
Astronomical and geographical causes,
comparative effects of, on climate,
207
Astronomical causes of cliangc of climate.
126
of glaciation, 140
Atlantic isles, peculiar mosses of, 368
Atlantosaurus, the largest land-anim.-il,
9S
Atriplex patula on a railway bank, 515
Auchenia, 27
Austen, Mr. Godwin, on littyral shells in
deep water, 337
Australia, two .sets of Northern i>lants in,
523
South Kurojiean i>lant.s in, 523
1 .\uslralia ami South Africa, aupp<».sc»l
Connection of, 525
550
INDEX
Australian Alps, indications of glaciation
in, 163
liirrls absent from New Zealand,
483
flora, general features of, 491
richest in temperate zone, 491
recent and derivative in the tropics,
492
its south-eastern and south-western
divisions, 493
Sir Joseph Hooker on, 494
geological explanation of, 494
its presence in New Zealand, 498
natural orders of, wanting in New
Zealand, 490
orchidese in China, 527
genera of plants in India, 524
plants absent from New Zealand,
488, 490
none in north temperate zone, 527
running wild in Neilgherrie moun-
tains, 528
region, definition of, 45
mammals and birds of, 46
seeds scattered in New Zealand,
508
Avlward, Captain, on glaciation of South
Africa, 163
Azores, 247
absence from, of large-fruited trees
or shrubs, 260
zoological features of, 248
birds of, 249
insects of, 258
beetles of, 253
land-shells of, 250
flora of, 256
Azores and New Zealand, identical plants
in both, 512
Azorean bird-fauna, origin of, 250
fauna and flora, deductions from,
261
plants, facilities for the dispersal of,
260 '
B.
Bahirusa alfurus in Celebes, 456
Badgers, 41
Bahamas contrasted with Florida, 5
Baker, Mr., on flora of Mauritius and the
Seychelles, 441
Bali and Lombok, contrasts of, 4
Banca, peculiar species of, 386
linrbarea precox on railway bank, 514
Barn-owl, wide range of, 15
Baron, Rev. R., on the flora of Madagascar,
441
Barriers to dispersal, 73
Batrachia, 30
Bats in Bermuda, 269
Bears of Europe and America, 14
Beaver of Europe and America, 14
Beetles of the Azores, 253
remote affinities of some of, 255
of the Galapagos, 284
of ot. Helena, 298
of the Sandwich Islands, 31S
Beetles, peculiar British species of, 351
Bell-birds, distribution of, 24
Bennett, Mr. Arthur, on peculiar Briti.sh
plants, 360
on the vegetation of railwav banks,
514
Bentham, Mr., on the comi)ositge of the
Galapagos, 288
on the compositse of St. Helena, 307
on the Mascarene compositge, 445
on Sandwich Island compositse, 325
Bermuda, 262
soundings around, 263
red clay of, 265
zoology of, 266
reptiles of, 266
birds of, 266
insects of, 269
land-moUusca of, 270
flora of, 271
Bermuda and Azores, comparison of liird-
faunas of, 268
Bernicla sandvichentis, 314
Biological causes which determine dis-
tribution, 532
Biological features of Madagascar, 416
Birds as plant-disperscrs. 81
as seed-carriers, 81, 258
conmion to Great Britain and Japan,
396
common to India and Japan, 399
specific range of, 15
range of British, 34
range of East Asian, 38
variation in N. American, 58
dispersal of, 75
of the Azores, 249
of Bermuda, 266
of Bermuda and Azores compared,
268
of the Galapagos, 280
of the Sandwich Islands, 313
peculiar to Britain, 340
of Borneo, 377
of Java, 382
of the Philippines, 388
of Japan, 396
peculiar to Japan, 398
peculiar to Formosa, 404
common to Formosa and India or
Malaya, 407
of Madagascar, and their teachings,
422
of Comoro Islands, 429
of the Seychelles, 430
of the Mascarene i-slands, 436
of islands east and west of Celebes,
454
of Celebes, 458
peculiar to Celebes, 459
Himalavan types of, in Celebes, 462
list of, in Celebes, 466
of New Zealand, 476, 482
wingless, of New Zealand, 476
Blackburn, Mr. T., on the beetles of the
Sandwich Islands, 318
Blakiston and Prver on birds of Japan,
396
IXDKX
Bland, Mr., on land-sliells of Bermuda,
270
Blanforil, Mr. W. T., on small effect of
marine dcmulation, 225
Blanford, Mr. H. F., on former connection
of Africa and India, 42ti
Blocks, travelled and perclied, 109
Blue magpies, range of, 15
Borneo, geology of, 375
mammalia of, 376
birds of, 377
affinities of fauna of, 381
Borneo and Asia, resemblance of, (5
Borneo and Java, 373
Boulder-beds of the carboniferous forma-
tion, 201
Boulder clays of east of England, 118
Bovidic, 29
Brady, Mr. H. B., on habitat of globi-
gerinje, 92
Braithwaite, Dr. R., on peculiar British
mosses, 365
Britain, probable climate of, with winter
in aphelion, 156
British birds, range of, 34-38
British Columbia, interglacial warm
periods in, 121
British fauna and flora, peculiarities of,
370
British Isles, recent changes in, 332
proofs of former elevation of, 334
submerged forests of, 335
buried river channels of, 336
last union of, with continent, 337
why poor in species, 338
peculiar birds of, 339
fresh-water fishes of, 340
peculiar insects of, 344
peculiar Lepidoptera of, 347
peculiar Coleoptera of, 351
peculiar Trichoptera of, 355
peculiar land and fresh-water shells
of, .356
pecidiarities of the flora of, 360
peculiar mosses and Hepaticie of, 366
British mammals as indicating a zoologi-
cal region, 33
BuIIer, Sir W. L., on the New Zealand
rat, 475
Buried river-channels, 336
Buteo solitarius, 314
Butterflies of Celebes, peculiar shape of,
463
Butterflies, peculiar British, 347
Caddis-flies peculiar to Britain, 355
Ca-cilia, species of, in the Seychelles, 432
wide distribution of, 432
CaciliadfP, 28
Callithea Leprieuri, distribution of, IS
Callithea aapphira, 18
Camels as destroyers of vegetation, 296
former wide distribution of, 421
Camelus, 17, 27
Campanula ridalii, 261
Canis, 17, 26
Carabus, numerous speoies of, 42
Carboniferous bouldor-beds, 201
warm Arctic climate, 201
Carnivora in Madagasc^ir, 417
Carpenter, Dr., on habitat of globigcrina^,
Carpenter, Mr. Edward, on Mars and
glacial periods, 164
Cardnus marianus in New Zealand, 515
Carpodacus purpureus and P. calif ornicu*.
68
Castor, 17
Casuarina, 1S5
in India, 527
Cause of extinction, 63
Caves of Glamorganshire, 336
Cebibae, overlapi>ing genera of, 29
Celebes, physical features of, 451
islands around, 452
zoology of, 455
derivation of mammals of, 457
birds of, 458
not a continental island, 461
insect peculiarities of, 462
Himalayan types in, 462
peculiarity of butterflies of, 463
list of land-birds of, 466
Centetidffi, 27
Centetida?, formerly inhabited Europe,
420
Central America, mixed fauna of, 53
Ceratodus, or mud-fish, 69
Cervus, 17, 26
Chalk a supposed oceanic formation, 89
Chalk at Oahu, analysis of, 90
Chalk, analysis of, 91
Chalk mollusca indicative of shallow watoi ,
93
Chalk .sea, extent of, in Europe, 93
Chalk-formation, land-plants found in.
94
deposited in an inland sea, 93
of Faxoe an ancient coral-reef, 94
modern formation of, 95
supposed oceanic origin of, erroneous,
96
" Challenger " soundings and shore-depo-
sits, 86
" Challenger " ridge in the Atlantic, 101
Chameleons verv abundant in Madagascar,
430
Chamois, di.stribution of, 13
Changes of land and sea, 83
Chasmorhynchus, distribution of, 24
C. nudicoilis, 24
C. tricarunculatus, 24
C. variefiatus, 24
C. nireuK, 24
Chilom/'nus lunata, .300
Chinchillas, 26
ClirvsochloridiP, 29
('i<'in«l(la, 17
Cicind(lid;i' common to South AmericA
and Madagascar, 28
Clay, nd, of Benin;da, 2ii.'.
Climate, astronomical causes of changes
of, 126
;52
INDEX
Climate, properties of snow and ice in
relation to, 131
of Britain with winter in aphelion,
156
of Tertiary period in Euroiie and
X. America, 178
temperate in Arctic regions, 181
causes of mild Arctic, 190
of Tertiary and Secondary periods,
199, 202
of the Secondary and Palaeozoic
epochs, 200
change of, during Tertiary and
Secondary Periods, 200
affected by arrangement of the
great continents, 205
nature of changes of, caused by high
excentricity, 230
exceptional stability of the present,
232
changes of, as affecting migration of
plants, 517
Climatal changes, 106
change, its essential principle re-
stated, 158
changes as modifying organisms,
229
Clouds cut off the sun's heat, 145
Coal in Sumatra, 385
Coast line of globe, extent of, 221
Cochoa, distribution of, 25
Cockerell, Mr. Th. D. A., on slugs of
Bermuda, 271
on British land and fresh-water shells,
356
Cold alone does not cause glaciation,
135
how it can be stored up, 133
Coleoptcra of the Azores, 253
of St. Helena, 298
of the Sandwich Islands, 318
pef'uliar British species of, 351
Comoro Islands, 428
mammals and birds of, 428
Composita?, of tlie Galapagos, 288
of St. Helena, 307
of the Sandwich Islands, 325
of the Mascarene Islands, 445
species often haye restricted ranges.
504
Conclusions on the Xew Zealand flora,
506
Contemporaneous formation of LoAver
Greensand and Wealden, 221
Continental conditions throughout geo-
logical time, 97-99
changes and animal distribution, 102
extensions will not explain anomalous
facts of distribution, 449
Continental islands, 243
of recent origin, 331
general remarks on recent, 408
ancient, 411
Continental period, date of, 337
Continents, moyements of, 88
permanence of, 97
general stability of, lol. 103
geological deyeiopment of, 205
Continuity of land, 74
Continuity of now isolated groups, proof
of, 70
Cook, Captain, on a natiye quadruped in
New Zealand, 476
Cope, Professor, on the Bermuda lizard,
266
Coracias iemminckii, in Celebes, 463
Coryus, 17
Cossonidse, in St. Helena, 299
Cretaceous deposits in North Australia,
493, 496
Cretaceous flora of Greenland, 185
of the United States, 189
Croll, Dr. James, on Antarctic icebergs,
136
on winter temperature of Britain
in glacial ejwch, 141
on diyersion of gulf-stream during the
glacial epoch, 143
' on loss of heat by clouds and fogs,
I 145
\ on geographical causes as affecting
' climate, 148
on ancient glacial epochs, ] 70
on uniyersality of glacial markings in
Scotland, 174
on mild climates of Arctic regions,
189
on ocean-currents, 190, 204
; on age of the earth, 213
I on mean thickness of sedimentary
rocks, 220
on small amount of marine denuda-
I tion, 225
! on buried riyer-channels, 336
Ctenodus, 69
Cyanopica, distribution of, 24
Cyanopica cooki, restricted range of, 15,
24
Cyanopica cyanus, 24
Cynopithecue nigrescens, in Celebes, 456
Dacclo, 47
Dana on continental upheayals, SS
on chalk in the Sandwich Islands, 90
on elevation of land causing the glacial
ei)Och, 152
on elevation of Western America,
194
on the development of continents,
205
on shore-deposits, 222
on life extermination by cold epochs,
230
Darwin, experiment on Helix vomatia,
78
on the permanence of oceans, 100
on cloudy sky of Antarctic regions,
146
on glaciers of the Southern Andes,
147
on geological time, 211
on complex relations of organisms,
226
on oceanic islands, 242
on seeds carried by birds, 257
IXDKX
■rSi
Darwin, experiments on sccd-ilisiicisal.
258
on natuial history of tlio Kfolin^'
Islands, 280
theory of formation of atolls, :Ui7
on cultivated plants not running; wilil,
.-^07
Hawkins, Professor Boyd, on animal mi-
grations dnring the glacial epoch,
120
Dawson, Mr. G. M., on alternations of
climate in British CoUunliia, 121
Professor, on Palteozoic boulder-beds
in Nova Scotia, 201
De Candolle on dispersal of seeds, SO
Dee]i-sca deposits, 219
Deer in Celebes, 456
Delphinium ajacis, on a railway bank, .">1'>
Dendrceca, 10
D. civrulea, 10
D. discolor, 10
D. dominica, 10
Dendrceca eoronata, variation of, 58
Dendro]ihida\ 2S
Denudation destroys the evidences of
;.daciation, 172
Denudation and deposition as a measure
of time, 213
Denudation in river basins, measurement
of, 215
Denudation, marine as compared with
sub-aerial, 225
Deposition of sediments, how to estimate
the average, 221
Deserts, cause of high temperature of,
132
Diagram of excentricitv and j. recession,
120
Diagram of excentricity for three million
years, 171
Didid;r, how exterminated, 43ti
Didnnculus. keeled sternum of, 437
Diospvros, in upper gn-ensand of Grocn-
land, 186
Diplotaxis viuralig, on railway bauUs, 513
Dipnoi, discontinuity of, 69
Dipterus, 69
Discontinuitv among North American
birds, 67
Discontinuity a proof of antiquity, 69
Discontinuous generic areas, 23
Discontinuous areas, 64
why rare, 64
Dispersal of animals, 72
of land animals, how effecteil, 73, 76
along mountain-chains, 81
of seeds by wind, 80, 257
by birds, 81, 258
l>y ocean-currents, 81, 258
of Azorean ]dants. facililics for, 260
Distribution, changes of, shown by extinct
animals, 102
how to explain anomalies of, 420
Drontheim mountains, peculiar mosses of.
Dobson, Mr., on bats of .Tapan, .':94
on the affinities of Mystocina tuber-
culata, 474
Do<lo, the, 436
abortrd wings of, 4.'<7
Dryiophid-.e. 28
Dnmeril. Professor, on lizard^ of Bourbon,
435
Duncan, Professor 1'. M., on ancient scft
of central Australia, 496
E.
Karly histoiy of New Zealand. 484
Earth's age, 210
East Asian birds, range of, 38
East and West Australian floras, grologi-
cal explanation of, 494
Echi<lna, 30
Echimyidie, 27
Elevation of North America during glacial
period, 154
causing diversion of gulf-stream. 154
Elwes, Mr. H. J., on distribution of
Asiatic birds, 380
Emberizn scheeniclus, discontinuity of, 06
E. jiasserina, range of, 6t>
/;,". pyrrhulina, 6G
Endemic genera of plants in Maurifitis.
&c., 443
Pndemic genera of plants in New Zealand,
526
English plants in St. Helena, 297
Environment, change of, as modifying or-
ganisms, 225
Eriocaulon grpiangulare, 363
Ethiopian Region, definition of, 42
l)irds of, 43
Etting.shausen. Baron von, on the fossil
flora of New Zealand, 490
on Australian plants in England. 51S
Eucalvptus, wide ranw of, in Australia,
'l85
Eucalvptus and Acacia, why not in New
"Zealand, 507
Eucalyptus in Eocene of Sheppey, 518
J]upetes, distriluition of, 25
Europe, Asia, &c., as zoological terms, 32
European birds, range of, 16
in Bermuda, 269
European occujiation, effects of, in St.
Helena, 294
European i)lants in New Zealan<l, 507
in Chile and Fuegia, 521
Everett, Mr., on Bomean birds, .377
on mammalia of the Philippines, 3R7
on Philippine birds. 388
on raised coral-reefs in the Philip
pines, 389
Evolution necessitates continuity, 70
Excentricitv and i>recpssion, rliagram of.
129
Excentricity, variations of, during thn-e
million years, 171
Excentricity a test of rival theories of cli-
mate, 171
Excentricity, high, its effects on warni
and cold climates, 198
Explanation of i>eculiarities of the fauna
of Celebes, 460
554
INDEX
Extinct animals showing changes of distri-
bution, 102
Extinct birds of the Mascarene Islands,
43(3
of New Zealand, 476
Extinction caused by glacial epoch, 122
Families, restricted areas of, 29
distribution and antiquity of, 68
Fauna and flora, peculiarities of British,
370
Fauna of Borneo, affinities of, 3S1
of Java, 382
of Java and Asia compared, 384
Faunas of Hainan, Formosa, and Japan
compared, 407
Felis, 17, 26
Ferns, abundance of, in Mascarene flora, 445
Ficus, fossil Arctic, 186
Fire-weed, the, of Tasmania, 513
Fisher, Rev. O., on temperature of space,
131
Fishes, dispersal of, 76
peculiar British, 340
cause of gi-eat speciality in, 343
mode of migration of fresh-water, 344
fresh-water, of New Zealand, 484
Floating islands, and the dispersal of ani-
mals, 74
Flora of the Azores, 256
of Bermuda, 271
of the Galapagos, 287
of St. Helena, 305
of the Sandwich Islands, 321 ; peculiar
features of, 323
peculiarities of the Briti.sh, 360
of Madagascar and the Mascarene
Islands, 439
of Madagascar and South Africa allied.
445
of New Zealand, 487
very poor, 488
its resemblance to the Australian, 480
its differences from the Australian,
490
origin of Australian element in, 498
tropical character of, explained, 500
summary and conclusion on, 506
Floras of New Zealand and Australia,
summary of conclusion as to, 542
Florida and Canada, resemblances of, 5
and Bahamas, contrasts of, 5
Fogs cut off the sun's heat in glaciated
countries, 145
Forbes, Mr. D., analysis of chalk, 91
Forbes, Mr. H. O.^ on plants of the
Keeling Islands, 286
Formosa, 400
physical features of, 401
animal life of, 401
list of mammalia of, 402
list of land-birds peculiar to, 404
Forests, submerged, 335
Fowler, Rev. Canon, on peculiar British
coleoptera, 346, 351
Freezing water liberates low-grade heat,
145
Fresh-water deposits, extent of, 97
organisms absent in St. Helena,
304
snail peculiar to Ireland, 356
fishes of the Seychelles, 433
Frogs of the Seychelles, 432
of New Zealand, 483
Fuegia, European plants in, 521
Fulica alai, 313
G.
Galapagos Islands, 275
Galapagos, absence of mammalia and am-
phibia from, 278
reptiles of, 278
birds of, 280
insects of, 284
land-shells of, 285
flora of, 287
and Azores contrasted, 290
Galbula cyaneicollls, distribution of, IS
rufoviridis, 18
viridis, 18
Galeopithecus, 63
Gallinula saiidvichenais, 313
Gardner, Mr. J. S., on Tertiary changes of
climate, 203
Garrulus, distribution of species of, 20
Garruhis glandarius, 21, 23, 65
G. cervicalig, 21
G. krynicki, 21
G. atricapilhis, 21
G. hyrcanus, 21
G. hrandti, 21, 23
G. lanccolatus, 22
G. bispccularis, 22
G. sinensis, 22
G. taivanus, 22
G. japonicns, 22, 65
Geikie, Dr. James, on interglarial de-
posits, 121
Sir Archibald, on age of buried river-
channels, 337
on stratified rocks being found near
shores, 87
on formation of chalk in shallow
water, 96
on permanence of continents. 104
on variation in rate of denudation.
173
on the rate of denudation, 215
on small amount of marine denuda-
tion, 225
Genera, extent of, 17
origin of, 61
rise and decay of, 64
Generic areas, 17
Generic and Family distribution, 25
Genus, defined an(i illustrated, 17
Geographical change as a cause of glacia-
tion, 148
changes, influence of, on climate, 150,
152
IXDF.X
o55
Geograpliical changos, cfTcct of, on Arctic
climates, 19.')
changes of Java and Borneo, 385
changes as modifying organisms, 228
Geological climates and geographical con-
ditions, 204
time, 210
change, probably quicker in remote
times, 223
time, value of the estimate of, 224
time, measurement of, 235
changes as aiding the migration of
plants, 519
climates as affecting distribution,
534
climates, summary of causes of, 536
time, siuamary of views on, 539
Geology of B(U-neo, 375
of Madagascar, 412
of Celebes, 451
of New Zealand, 472
of Australia, 494
Geomalacus maculosnx, 35(i
Glacial climate not local, 113
deposits of Scotland, 112
Glacial epoch, proofs of, 107
effects of, on animal life, 117
alternations of climate during, 118
as causing migration ai.n extinction,
122
causes of, 125
the essentials to the production of,
136
]n-obable date of the, 160
and the climax of continental develop-
ment, 206
date of last, 233
Glacial phenomena in North America,
116
Glaciation was greatest where rainfall is
now greatest, 139
action of meteorological causes on,
142
.summary of chief causes of, 144
in Northern Hemisphere, the only
efficient cause of, 144
of New Zealand and South Africa.
162
local, due to high excentricity, 207
Avidespread in recent times, 536
Gleichenia in Greenland, 186
in relation to chalk, 89
Globigerina-ooze. analysis of, 91
Globii,'erinne, where found, 92
Glyjitostrobus, fossil, 186
Goats, destructivcness of, in St. Helena,
205
Godman, Mr., on birds reaching the
Azores, 248, 250
Gray, Professor Asa, on extinction of
European i»lants by the glacial
eiioch, 123
Great Britain and Japan, birds common
to, 396
Greene, Dr. J. Reay, on chameleons in
Bourbon and Mauritius, 435
fireeidand, loss of sun-lieat bv clouds in.
147
Greenland, an anomaly in tlie Noriliorn
Hemisphere, 154
Miocene flora of, 183
Cretaceous flora of, 186
flora of ice-surrounded rocks of, 522
Grinnell Land, fossil flora of, 184
Guern.sey, peculiar caddis-fly in, .S."i5
Gulick, Rev. J. T., on Achatinellinrr, 318
Gunther, Dr., on gigantic tortoises, 270
on peculiar British fishes, 341
on Urotrichus gibsii, 394
on lizards in the London Docks, 431
on Indian toads in Mauritius, 4.38
Guppv, Mr., on chalk of Solomon Islands,
91
H.
Haast, Dr., on otter-like mammal in Nfw
Zealand, 475
Ilabitability of globe due to disproportion
of land and water, 209
ITapIothorax burchellii, 299
ITartlaub, Dr., on " Lemuria," 423, 426
Hatteria piinctata, 483
Haughton, Professor, on heat carried by
ocean-currents, 194
comparison of Miocene and existing
climates, 197
on geological time, 211, 219
on thickness of sedimentarv rocks,
219
Hawaiian fauna and flora, antiquitv of,
328
Heat and cold, how dispersed or stored up,
131
Heat required to melt snow, 134
evolved by frozen water, its nature
and effects, 145
cut off by clou<l and fogs, 145
Hector, Dr.. on Triassic and Jurassic
flora of New Zealaml, 52('.
Heer, Professor, on chalk sea in Central
Eurojie, 93
Heilprin, Professor, on insect-s of Bermuda,
269
on land-shells of Bermuda. 270
Helianthevium Breweri, 360, 363
Heliodus, an American fossil, 09
Helix, 17
Ilemipteraof St. Helena, .303
Hepatica-, ]ieculiar British, 3r,(;
non-European genera of, in Britain,
367
Hesperomys, 26
Hesperornis allied to ostriches, 481
Hieraeiiim iricum, 362
High land essential to tlie production of a
glacial ei>och, 195
Iliblebrand, Dr. W., on flora of tho
Sandwich Islamls, 321
Hima!j.> an birds and insects in Ci-Ii'Ik-s,
462
Hipi>opotamus in Yorkshire as jToving
a mild climate, 119
Hochstetter on the aqtiatic mammal of
New Zealand, 475
556
INDEX
Hooker, Sir Joseph, on the Galapagos
flora, 287
on affinities of St. Helena plants, 30G
on peculiar British plants, 360, 363
on tlie flora of Xew Zealand, 488
on proportion of temperate and
tropical Australian floras, 492
on current of vegetation from north
to south, 510
on supposed occurrence of Australian
plants in England in the Tertiary
period, 518
Home, Mr. John, on ice-sheet covering
the Isle of Man, 115
Hull, Professor, on Permian breccias in
Ireland indicating ice-action, 201
Humming-birds, restricted ranges of, 16
Hutton, Captain, on struthious birds of
New Zealand, 479
Huxlev, Professor, on geological time,
211
on European origin of African animals,
419
Hyomoschus, 27
Hyracoidea, restricted range of, 30
Ice-action, what evidences of, during the
Tertiary period, 178
indications of ancient, 200
Ice-borne rocks, a test of a glacial epoch,
176
in Miocene of N. Italy, 178
in Eocene of Alps, 178
in Eocene of Carpathians and Apen-
nines, 179
absence of, in English and N. Ameri-
can Tertiaries, 180
Ice-cap, why improbable or impossible,
161
Iceland, a continental island, 450
Icteridae, 50
Iguanidse, 50
Indian birds in Formosa, 407
Indian Ocean as a source of heat in Ter-
tiary times, 192
Indian genera of plants in Australia,
492
Indicator, distribution of, 25
Insectivora in Madagascar, 417
Insects, dispersal of, 77
of the Miocene period, 77
restriction of range of, 78
of the Azores, 253
of Bermuda, 269
of the Galapagos, 284
of St. Helena, 298
of the Sandwich Islands, 318
peculiar British, 344
of Celebes, peculiarities of. 462
scarcity of, in New Zealand, 505
Insular faunas, summary of conclusions as
to, 539, .542
Interglacial warm periods on the continent
and in North America, 121
Interglacial periods and tlieir probable
character, 152
Interglacial periods will not occur during
an epoch of extreme glaciation, 155
Interglacial climates never very warm,
159
Ireland, poverty of, in reptiles, 339
in plants, 339
peculiar fishes of, 342
plants of, not found in Great Britain,
364
Islands, classiflcation of, 242
importance of, in study of distribu-
tion, 241
remote, how stocked with plants
and animals, 261
submerged between Madagascar and
India, 425
Isle of Wight, peculiar beetle of, 351
Isatis tinctoria, on railway bank, 513
Ithaginis, 26
Japan, zoological features of, 393
mammalia of, 394
birds of, 396
birds peculiar to, 398
birds in distant areas, 399
Japan and Formosa, 391
Java, fuuna of, 382
Asiatic species in, 384
Java and Borneo, past changes of, 385
Jays, distribution of species of, 20
of Europe and Japan, 67
Jeffreys, Dr. Gwyn, on shallow-water
'molhisca in chalk, 92
on fossil shallow-water shells in deep
water, 337
Jones, Mr., on migration of birds to
Bermuda, 268
on vegetation of the Bermudas, 272
Juan Fernandez, flora and fauna of, 287
Judd, Prof. J. W., on absence of glacia-
tion in east Europe, 139
on glaciation of the Alps produced by
elevation, 179
Jiiniperus barbadenxis, 272
Jura, travelled blocks on, 110
Jurassic warm Arctic climate, 202
Keeling Islands, animals of, 286
Kirk, Mr. T., on temporary introduced
plants, 515
Knowledge of various kinds required for
stiidy of geographical distribution,
Lagopus scoticua, .340
Land as a barrier to cceau-curreuts, 150
INDEX
Land and sea, clianpes of, 83
how changes of, affect climate, 148,
I'.O
Land ami water, disproportion of, renders
globe hahital lie, 209
T.and-liirds of Celebes, list of, 400
Land-connection, how far necessary to
dispersal of mammals, 73
Land-shells, great antiquity of, 79
universal distribution of, 79
causes favouring the abundance of,
79
of the Azores, 250
of Bermuda, 270
of the Galapagos, 284
of St. Helena, a04
of the Sandwich Islands, ,"^10
of the Seychelles, 434
T.aurut canariensis, 200
Leguat on animals of Bourbon, 435
on the Solitaire, 430
Leguminosffi, abundance of, in Australia,
490
" Lemuria," a supposed submerged conti-
nent, 422-420
I;emurs in Madagascar, 410
Leudenfeld, Dr. R. von, on glaciation in
the Australian Alps, 103
Leopard, enormous range of, 14
Lepidoptera, list of peculiar British, 347
lA'pitlosiren, 63
Lepidosiren paradoxa and L. anneciens,
69
Lepidosternidse, 27
Limestone as indicating change of sea and
land, 84
Limncea involuta, 356
Linaria purpurea, on railway bank, 514
Liopelma hochstetteri, in New Zealaml.
483
Liotrichidse, 29
List of the land-birds of Celebes, 400
Lizard peculiar to the Mascarene Islands.
438
Lizards of the Galapagos, 278
local variation of colour of, 431
of New Zealand, 483
Lobeliacese, abundance of, in the Sandwich
Islands, 324
Locality of a species, importance of, 12
Loddigesia viirabilis, rarity fif, 10
Lord, Mr., on species of Urotrichus,
394
Low-gi-ade and high-grade heat, 145
Lowlands nowhere covered with perpetual
snow, 136
Lundy Island, peculiar beetles of, 354
Lvell, Sir Charles, on permanence of con-
tinents, 84
on calcareous mud, 90
on the distribution of clialk, 93
on geogra]>hical causes as modifying
climate, 148
on estimate of geological time, 211.
235
on classification of se<limentarv rooks,
217
Lynxes, a Paliearotic group, 41
M.
McLachlan, Mr., on peculiar Briti.sh cad-
dis-flies, :{55
Madagascar, ]diysical features of, 412
former comiitiou of, 414
biological features of, 416
mammalia of, 410
reptiles of, 417
relation of, to Africa, 418
earlv history of, 419
birds of, in relation to "Lemuria,"
422
flora of, 439
conclusion on fauna and flora of,
440
great antiquity of, 440
Madagascar and Africa, contrast of, 0
Maillard on animals of Bourbon, 435
Malav Islands, local peculiarities of flora
' in, 187
past historj' of, »89
Malayan birds in Formosa, 400
Mamiualia of East Asia, range of, 34
of North Africa, range of, 34
Mammalia, dispersal of, 7:<
of Britain, range of, 33
poverty of, 329
of Borneo, 370
of Java, 382
of the rhilippines, 387
of Japan, ,393
of Formosa, 402
common to Formosa and India, 403
of Madagascar, 410
of Comoro Islantls, 428
of Celebes, 455 ; whence derived, 457
of New Zealand, 474
Maori legend of origin of the forest-rat,
475
Maoris, their accounts of th - moa, 477
Map of the old Rhone glacier. 110
of North and South Polar Regions.
138
of the Azores, 24S
of Bermuda, 203
of the Galapagos, 270, 277
of the South Atlantic Ocean, 293
of the Sandwich Islands. 311
of the North Pacific with its sub-
merged banks. 312
..f British Isles and the lOO-fathoni
bank, 333
of Borneo and Java, 374
nf Japan and Formosa, :<92
j.livsical, of Ma.lagascar, 413
of the Madagascar group. 415
of the Indian Ocean. 425
of Celebes, 452
of sea-bottom around New Zealand,
472
of Australia in Cretaceous jitriod,
497
^Slarcon, Professor Jules, on the Pliocene
and glacial epoclis, 233
Marmot, range of, 15
Mars as illustrating glacial the««ries. 104,
108
558
INDEX
Mars, no true ice-cap on, 166
Marsupials, range of, 30
Marsh, Prof. O. C, on the Atlantosanrns,
98
on Hesperornis, 481
Marsh, Mr., on camels as desert-makers.
296
Mascarene Islands, 428-445
Mascarene plants, curious relations of,
442
endemic genera of, 443
Mascarene flora, fragmentary character of,
444
abundance of ferns in, 445
Mauritius, Bourbon, and Rodriguez, 434
Measurements of geological time, 233
agreement of various estimates of,
235
concluding remarks on, 236
Medicago sativa in Xew Zealand, 515
Megalgemidae, 27
Meleagris, 50
Melilotus vulgaris, on railway banks, 513
Meliphagidse, 47
Melliss, Mr., on the early history of St.
Helena, 295
Melospiza melodia, variation of, 58
Merycotherium, 123
Meteorological causes as intensifying gla-
ciation, 142
Migration caused by glacial epocli, 122
of birds to Bermuda, 267
of plants from north to south, 512
of plants and alterations of snow line,
516
of plants due to changes of climate,
517
of plants from north to south, long
continued, 518
of plants aided bv geological changes,
519
of plants bv wav of the Andes,
520
of plants by way of Himalayas and
South Asia, 523
of plants through Africa, 524
Mild Arctic climates, stratigraphical evi-
dence of, 187
causes of, 190
dependent on geographical changes,
191
effects of high excentricity on, 19S
suTumary of causes of, 537
Miocene Arctic flora, 183
flora of Europe, 123
or Eocene floras, 185
deposits of Java, 385
fauna of Europe and North India,
419
Mississippi, matter carried aAvay by, 172
Mitten, Mr. William, on peculiar British
mosses and hepaticse, 365, 368
on temporary appearance of plants,
513
Mniotiltidae, a nearctic group, 49
Mnium, peculiar species of, in the Dront-
heim mountains, 36S
Moas of Xew Zealand, 47t;
MoUusca, dispersal of, 78
I Monotremata, restricted range of, 30 i
J Moraines, 108
of Ivrea, 116
( More, Mr. A. G., on peculiar Irish plants,
364
Morgan, Mr. C. Lloyd, on thickness of
formations jiot affected by denuda-
: tion, 220
Moseley, Mr. H. N., on seeds carried by
birds, 259
j on the flora of Bermuda, 272
I Mosses, peculiar British, 366
I non-European genera of, in Britain,
! 367
how diffused and whv restricted,
368
Mt. St. Elias, why not ice-clad, 154
Mountain chains aiding the dispersal of
plants, 81
as aids to migration of plants, 513
Mueller, Baron von, census of Australian
plants, 492
Munia brunneiceps, in Celebes, 463
Murray, Mr. J., on oceanic deposits, SO
on chalk-like globigerina-ooze, 92
on mean height of continents, 210
on land-area of the globe, 221
Mus, 17, 26
Mygale pyrenaica, range of, 15, 24
M. muscovitica, 24
Myialeates helianthea in Celebes, 403
Myricafaya, 260
Myrsine, fossil in Greenland, ISO
Mytilus edulis, sub-fossil in Spitzbergen,
182
X.
Xares, Capt. Sir G., on snow and ice in
high latitudes, 135
on abrupt elevation of Bermuda, 204
Xearctic Region, definition of, 48
mammalia of, 48
birds of, 49
reptiles of, 50
Nectarinea osea, restricted range of, 16
Xeilgherries, Australian plants natura-
lized in, 528
Xeotropical Region, definition of, 51
low types of, 52
Xevill, Mr. Geoffrey, on land-shells of the
Seychelles, 434
on destruction of Seychelles flora, 445
Xew species, origin of, 56
Xewton, Mr. E., on short wings of the
Seychelles dove, 437
Xewton. Professor, on recently extinct
birds, 437
Xewts, restricted range of, 30
Xew Zealand, recent glaciation of, 163
Xew Zealand, 471
geology of, 472
form of sea-bottom around, 473
zoological character of, 473
mammalia of, 474
INDEX
r.r>9
New Zealand, wingless birds of, 47ii
past changes of, 47.H
•winged birds and lower vertebralts
of, 482
deductions from peculiarities of fauna
of, 484
period of its union with N. Australia,
484
the flora of, 487, V.OG
origin of Australian element in the
tlora of, 498
tropical cliaracter of flora, 500
tropical genera common to Australia,
501
temperate species common to Aus-
tralia, 502
route of Arctic plants to, 521
European plants in, 509
endemic genera of plants in, 52»'>
great antiquity of, 526
Nordenskjold, Prof., on absence of per-
petual snow in N. Asia, 135
on recent milder climate in Spitz-
bergen, 182
on former Polar climates, 187
on geology of Spitzbergen, 188
North America, glacial phenomena in.
116
interglacial warm periods in, 121
condition of, in Tertiary period, 194
Northern genera of plants in S. temperate
America, 521
hemisphere, absence of southern
plants from, 527
flora, hardiness of, 528
Ocean-currents as carriers of plants, 81
as affecting interglacial periods, 152
as determining climate, 153
efl'ects of, in Tertiary times, 196
Ocean, Darwin on permanence of, 100
Oceanic and continental islands, 242
Oceanic islands a proof of the permanence
of oceans, 100
Oceanic islands, 244
— the Azores, 247
general remarks on, 329
Octodontidse, 27
(Enanthe fluviatilis, 361
(Eninghen, Miocene flora of, 18;'.
(Enothera odorata, on a railway bank,
514
Oliver, Professor, on peculiar Bermudan
plants, 272
Operculata, scarcity of, in the Sandwich
Islands, 317
Ophrijs apifera, temporary appearance of,
514
Orchideaj, species haye restricted ranges,
505
Orcluds, abundance of, in Bourbon and
Mauritius, 446
T/hy iilmost uniyersal in the troj^ics
Orders, distribution of, 30
Organic cliaiige dejiendent on cliangi- of
conditions, 225, 228
Oriental Region, definition of, 44
mammals and birds of, 44
reptiles of, 45
insects of, 45
Origin of new species, 56, 60
of new genera, 61
of the Galapagos flora, 2ss
of tlie beetles of St. ll.-lena, 298
of Australian element in the New
Zealand flora, 498
Orkney, peculiar fishes of. 341
Orthonyx not a New Zealand genus,
483
Osprey, wide range of, 15
Ostriches, limitation of, 30
Otter-like mammal in New Zealand, 475
Oyerlapping and discontinuous areas, 28
Pachyglosta aureolimbata, in Celebes.
463
Palsearctic Region, limits of, 39
characteristic features of. 41
Pala;ozoic formations, depth of, round
London, 218
Palm confined to Round Island, 444
Panax, fos.sil in Greenland, 186
Papilio, 17
Paraguay, no wild horses or cattle in,
226
Parnassius. Palaiarctic, 42
Parus ater, 19
P. borealis, 19, 64
P. britannicus, ."'.21
P. camtschatkensis, 19
P. cinctHS, 20
P. caruleus, 20
P. cyaneiix, 20
P. cristatus, 20
P. Icdouci, 20
P. luguhris, 20
P. major, 19
P. palugiris, 19; discontinuous area of,
65
P. rosra, 340
P. teneriffcr, 20
Passercs of the Sandwich Islands, 314
Past changes of New Zealand, 47S
I Pa3-er, Lieut., on eyaporation of ice tlur-
j ing the Arctic summer. 140
Peculiar fauna of New Zealand, deduc-
tions from, 484
I Pengelly, Mr., on submerged forests. 335
Pennula millei, in Sandwich Islands,
313
I Permanence of continents, summar>- of
j eyidence for, 103
Permian formation, indications of ice-
' action in, 200
Perodicticus, a local genus, 26
Petroielinum segetiim, on railway kmk,
514
560
INDEX
Philippine Islands, 387
inainmalia of, 387
birds of, 388
past history of, 389
Phyllodactylns galapagensia, 279
Phylloscopus borealis, range of, 15
Physical causes which deternnne distribu-
tion, 533
features of Formosa, 401
Pica, 17
Pickering, Dr., on the flora of the Sand-
Avich Islands, 323
on temperate forms on mountains of
the Sandwich Islands, 323
Pithecia monachus, distribution of, 18
P. rufiharbata, 18
Pitta, distribution of, 25
Plants, dispersal of, 80
seeds of, adapted for dispersal, 80
■wide range of species and genera of,
185
poverty of, in Ireland, 339
peculiar British, 359
of Ireland not in Great Britain, 364
cause of their wide diffusion and nar-
row restriction, 369
easily dispersed often have restricted
ranges, 504
how tliev migrate from north to soutli,
512
of existing genera throughout the
Tertiary period, 520
southern migration of, by way of the
Himalayas, 523
southern migration of, througli Africa,
524
endemic genera of, in New Zealand,
526
Platypus, 30
Plesiiodon longirostris of Bermuda, 266
Po, matter carried away by, 173
Podargus, Australian genus, 47
P(tcilozonites, peculiar to Bermuda, 270
Poinciana regia in Madagascar, 440
Populus, fossil in Spitzbergen, 184
Pourtales, Count, on modern formation
of chalk, 95
on sedimentary deposits in Gulf of
Mexico, 222 '
Poverty in species of Britain, 338
Precession of Equinoxes, influence of, on
climate, 126
Preservation of species, 63
Proboscidea, range of, 30
Proteus, why preserved, 63
Psophia, range of species of, IS
Pteroptochidse, 29
Pyrenean ibex, restricted range of. 15
R.
Railways, new plants on, 513
Ramsay, Mr. Wardlaw, on Philippine
birds, 3SS
Professor, on ancient land surfaces,
99
Ramsay, Professor, on geological time
212
on thickness of sedimentary rocks,
219
Rat, native, of New Zealand, 475
Rate of organic change usually measured
by an incorrect scale, 232
Rats in the Galapagos, 278
Raven, wide range of, 15
Reade, T. Mellard, on changes of sea and
land, 84
Recent continental islands, 243, 331
Red clay of Bermuda, 265
Reptiles, dispersal of, 75
of the Galapagos, 278
of the Sandwich Islands, 316
cause of scarcity of, in British Isles,
339
of Madagascar, 417
of tlie Seychelles, 430
of Mauritius and Round Island, 438
of New Zealand, 483
Ehodolcena altivola in Madagascar, 440
Rhus toxicodendron in Bermuda, 272
Ridgway, Mr., on birds of Galapagos, 281
River-channels, buried, 336
Roches moutonnies, 108
Rodents in Madagascar. 417
Round Island, a snake and a palm peculiar
to, 438, 444
Rumex imlcher in New Zealand, 515
Rye, Mr. E. C., on peculiar British in-
sects, 345, 351
St. Helena, 292
effects of European occupation on the
vegetation of, 294
insects of, 298
land-shells of, 304
absence of fresh-water organisms in,
304
native vegetation of, 305
Salvin, Mr., on the birds of the Galapagos,
280
Sandwich Islands, the, 310
zoology of, 313
birds of, 313
reptiles of, 316
land-shells of, 316
insects of, 318
vegetation of, 321
antiquity of fauna and flora of, 328
Sassafras, in Swiss Miocene, 183
Scandinavian flora, aggressive j)ower of,
511
Scientific voyages, comparative results
of, 7
Sciurus, 26
Sclater, Mr. P. L., on zoological regions,
32, 39
Scotland, glacial deposits of, 112-115
probable rate of denudation in, 173
Miocene flora of, 184
peculiar fishes of, 341
INDEX
161
Scotophilus tuberculatus in New Zealand,
474
Scropliularinc.T, wliy few species arc coiii-
mou to Australia and New Zealand,
505
Sea, depth of, around Madagascar, 414
depth of, around Celebes, 452
Sea-bottom around New Zealand and Aus-
tralia, 47;}
Sea-level, changes of, dependent on gla-
ciation, 1(31
complex eftects of glaciation on, 102,
164
rise of, a cause of denudation, 174
Seas, inland, in Tertiary period, 191
Section of sea-bottom near Bermuda, 204
Sedges and grasses common to Australia
and New Zealand, 504
Sedimentary rocks, how to estimate thick-
ness of, 217
thinning out of, 217
how formed, 218
tliickness of, 217, 221
summary of conclusions on the rate
of formation of the, 221
Scebolim, Mr., on Parus palustris, 05
on Emhcriza sclKenichis, 00
on snow in Siberia, 100
on birds of Japan, 396
Seeds, dispersal of, 257
carried by birds, 25S
Senecio australis, on burnt ground,
513
Sericinus, Pala^arctic, 42
Seychelles Archipelago, 429
birds of, 430
reptiles and anijihibia of, 430
fresh- water fishes of, 433
land-shells of, 434
Sharp, Dr. D., on beetles of the Sandwich
Islands, 319
on peculiar British beetles, 345
Shells, peculiar to Britain, 350
Shetland Isles, peculiar beetle of, 354
Shore deposits, 85, 21 1
proving the i)ermanencc of continents.
97
distance from coast of, 221
Sialia sialis, variation of, 58
Siberia, amount of snow and its sudden
disajipearancc in, 100
Silurian boulder-beds, 201
warm Arctic climate, 202
Simiidac, 27
Sisyrinchium hermtidianum, 272
Skertchlev, Mr., on four distinct boulder-
clays, 118
on Tertiary deposits in Egypt and
Nubia, 191
on climatic stabilitv of present epoch,
233
Slug peculiar to Ii-eland, 356
Snake jjcculiar to Hound I.sland, 438
Snakes of the Galaiiagos, 280
of the Seychelles; 431
Snow and ice, properties of, in relation to
climate, 131
Snow, effects of, on climate, 133
Snow, quantity of lieat required to melt,
134
often of small amount in liigh lati-
tudes, 135
never perpetual on lowlands, 136
conditions determining perpetual,
maintains cold by reflecting the solar
heat, 144
Snow-line, alterations of.causing migration
of plants, 510
Sollas, Mr. J. W., on greater intensity of
telluric action in past time, 223*
South Africa, recent glaciation of, 103
many northern genera of plants in,
524
its supposed connection with Aus-
tralia, 525
South American plants in New Zealand,
521
South Temperate America, poor in species,
58
climate of, 140
Southern flora, comparative tenderness
of, 528
Southern ])lants, why absent in the
Northern Hemisphere, 527
Space, temperature of, 129
Specialisation antagonistic to diffusion of
species, 505
Species, origin of new, 56
extinction of, 03
rise and decay of, 64
epoch of exceptional stability of, 232
dying out and replacement of, 409
preservation of, in islands, 410
Specific areas, 14 ; discontinuous, 04
Spiranthes romanzoviana, 304
Spitzbei-gen, Miocene flora of, 1S4
absence of boulder-beds in, 187
Spruce, Dr. Richard, on the dispersion ot
hepatic*, 3ti9
Stability of extreme glacial conditions,
159
Stainton, Mr. H. T., on peculiar British
moths, 340-350
Stanivoi mountains, whv not ice-clad
154
Starlings, genera of, in New Zealand,
482
Stellaria media, temporary appearance of,
515
Sternum, process of abortion of keel of,
437
Stow, ^Ir. G. W., on glacial phenomena
in South Africa, 103
Stratilied rocks formed near shores, 85,
87
deposits, how formed, 218
Striated rocks, 107
blocks in the Permian formation,
200
Strixflammea, range of, 15
Strutliiones, 30
Struthious birds of New Zealand as indi-
cating jiast changes, 478
Stylidium, wiile range of, 185
Submerged forests, .334
O O
562
INDEX
Sul)sidence of istlmius of Panama, 151
Sumatra, geology of, 385
Sweden, two deposits of " till " in, 121
Swimming powers of mammalia, 7-4
Swinhoe, Mr. Robert, researches in For-
mosa, 400
Switzerland, interglacial warm periods in,
121
Sylviadaj, overlapping genera of, 29
Talpidfe, a Palcearctic group, 41
Tapirs, distribution of, 25
foi-mer wide range of, 393
Tarsius, 03
Tarsius gpectrum in Celebes, 45(5
Tasmania and North Australia, resem-
blance of, 5
route of Arctic jilants to, 520
Taxodium distichum in Spitzbergen, 184
Temperate climates in Arctic regions.
181
Australian genera of plants in New
Zealand, 502
Australian species of plants in New
Zealand, 502
Temperature, how dependent on sun's
distance, 129
of space, 129
Tertiary glacial epochs, evidence against,
179
warm climates, continuous, 187
Test of glaciation at any period, 175
Testudo abingdonii, 279
T. microphyes, 278
Tetraogallus, distribution of, 24
Thais, a Palsearctic genus, 42
Thomson, Sir William, on age of the earth,
213
Sir Wyville, on organisms in the
globigerina-ooze, 89
analysis of globigerina-ooze, 91
Thryothorus hetvickii, discontinviity of,
08
'^Till" of Scotland, 112
several distinct formations of, 121
Tits, distribution of species of, 19
Torreya, fossil in Spitzbergen, 180
Tortoises of the Galajiagos, 278
Trade-winds, how modified by a glacial
epoch, 142
Tragulidaj, 27
Travelled blochs, 109
Tremarctos, an isolated genus, 29
Triassic warm Arctic climate, 200
Tribonyx not a New Zealand genus,
483
Trichoptera peculiar to Britain, 355
Trogons, distribution of, 28
Tropical affinities of New Zealand bii'ds,
483
character of the New Zealand flora,
cause of, 500
genera common to New Zealand and
Australia, 501
Turdus, 17, 26
Turdus fuscescens, variation of, 58, 59
Tylor, A. , on estimating the rate of denu-
dation, 214
Tyrannidaj, an American family, 50
U.
Uraniida?, 28
Uropeltidffi, 30
Urotrichus, distribution of,
Ursus, 20
Variation in animals, 57
amount of, in N. American birds,
58
Vegetation, local peculiarities of, 185
eflects of Polar night on, 198
Vespcrugo serotinus, range of, 14
Vireo hellii. supposed discontinuitv of,
68
Vireonidff, an American familv. 49
W,
Wallich, Dr., on habitat of globigerinw,
92
Warren, Mr. W., information on British
lepidoptera, 347
Water, properties of, in relation to climate,
131, 133
Waterhouse, Mr., on Galapagos Ijeetles,
284
Wales, peculiar fish of, 341
Warm climates of northern latitudes, long
persistence of, 201
Watson, Mr. H. C, on tlie flora of the
Azores, 250
on peculiar British plants, 859
on vegetation of railway banks, 513
Webb, Mr., on comiiarison of Mai's and
the Earth, 100
West Australia, rich flora of, 494
former extent and isolation of, 497
West Indies, a Neotropical district, 53
White, Dr. F. Buchanan, on the Hemiptera
of St. Helena, 303
Mr. John, on native accounts of the
moa, 477
Whitehead, Mr. John, on Bornean birds,
377 ■
Wilson, Mr. , Scott B., on birds of the
Sandwich Islands, 314
Winged birds of New Zealand, 482
Wingless birds never inhabit continents,
437
their evidence against "Lemuria,"
438
of New Zealand, 470
Wings of struthious birds show retrograde
development, 437
INDEX
563
Winter teiniicrature of Euroi'C and Aimi--
ica, 190
"Wolf, range of, M
Wollastou, Mr. T. V., on insular cliaractcr
of St. Helena, I'O-J
on St. Helena .slicUs and insects,
297
■Wood, Mr. Searles V., jnn., on formation
of "till," 114
on alternations of climate, US
on cau.ses of glacial epochs, 125
conclusive objection to the excen-
tricity theory, 100
on continuou.s warm Tertiary cli-
mates, ISO
Woodward, Dr. S. V., on Annnonites
liviuLr in shallow water, 9i>
Woodward, Air., on "Lenmria," 426
Wright, Dr. Tercival, on lizards of the Sej--
chelles, 431
Young, Professor J., on contemporaneous
formation of dejiosits, 221
Young Island, lofty Antarctic, 522
Zoology of the Azores, 24S
of Bermuda, 262
of the Sandwich Islands, .']1.1
of I5orneo, .'iTO
of Mada'cascar, 416
of islands round Celebes, 4i.3
of Celebes, 4:,:,
Zoological and geographical regions com-
pared, .'^2, r)4
Zoological features of Japan, 393
character of New Zealand, 473
THE END
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