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ed 


By ALFRED RUSSEL WALLACE. 


THE MALAY ARCHIPELAGO. Extra crown 8vo, 7s. 6d. 

NATURAL SELECTION AND TROPICAL NATURE. 
Extra crown 8vo, 7s. 6d. 

ISLAND LIFE. Extra crown 8vo, 7s. 6d. 

THE GEOGRAPHICAL DISTRIBUTION OF ANIMALS. 
In two vols. _Medium 8vo, 42s. 

DARWINISM. Extra crown 8vo, 7s. 6d. 


STUDIES SCIENTIFIC AND SOCIAL. 2vols. Extra 
crown 8vo, 18s. 


IS MARS HABITABLE? Extra crown 8vo, 2s. 6d. 
Lonpon: MACMILLAN AND CO., Lrp. 


— 


‘AYP OD ep enani0adol9 [f-STOUNWHADE YD Of O1SUIS “YG SILOPNWIEAG29 “9 ‘g- eno} 0070) DLP UDL"E "2 GS TALDOA NY 2 G-SVYPLLODLLYD “2 TLYPTULLY “D2 SYOVALII “YY “soapy STYNLIDY “fp 
spigpunns . | 


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ane see ee ee ee “ —— oe a ee —_— —— ee os —-— 


‘SAV?’ TOL FHL AO NOWOEGTHISTIG WL ONIMAHS dVW 


ISLAND LIFE 


OR 


THE PHENOMENA AND CAUSES OF 


INSULAR FAUNAS AND FLORAS 


INCLUDING A REVISION AND ATTEMPTED SOLUTION OF 
THE PROBLEM OF 


GEOLOGICAL CLIMATES 


BY 


ALFRED RUSSEL WALLACE 


AUTHOR OF ‘‘THE MALAY ARCHIPELAGO,” ‘‘THE GEOGRAPHICAL DISTRIBUTION OF 
ANIMALS,” ‘‘ DARWINISM,” ETC. 


THIRD AND REVISED EDITION 


MACMILLAN AND CO., LIMITED 
ST. MARTIN’S STREET, LONDON 
be ikd 


RICHARD CLAY AND Sons, LIMITED, 
BRUNSWICK STREET, STAMFORD STREET, S.-E. 
AND AT BUNGAY, SUFFOLK. 


First Edition printed 1880 (Med. 8vo). 
Second Edition 1892 (Extra cr. 8vo). Reprinted 1895, 1902, 1911. 


50 F . 


LIBRARY 
os 
SE my OF oie 


QH 3s 
WAY 
GY / | 


TO 
SIR JOSEPH DALTON HOOKER, 


K.C.S.I., C.B., F.R.S., ETC., ETC. 
WHO, MORE THAN ANY OTHER WRITER, 
HAS ADVANCED OUR KNOWLEDGE OF THE GEOGRAPHIVAL 
DISTRIBUTION OF PLANTS, AND ESPECIALLY 


OF INSULAR FLORAS, 


I Dedicate this Volume; 


ON A KINDRED SUBJECT, 


AS A TOKEN OF ADMIRATION AND REGARD. 


PREFACE TO THE THIRD EDITION 


In the ten years that have elapsed since the second 
edition of this work was published in 1891, numerous ex- 
plorers and collectors have largely increased our knowledge 
of the forms of life in the less known regions of the globe, 
and many of the more interesting islands and archipelagoes 
have received special attention. 

This has resulted in a very large increase in the number 
of species of animals and plants known to inhabit them, 
especially in the more popular groups such as the birds, 
and in a less degree in mammalia and some orders of 
insects, as well as in the terrestrial mollusca. This has 
necessitated a complete revision of the lists of species in 
many of the islands, and sometimes in a modification of 
the conclusions drawn from them. In the two most 
remarkable Oceanic Islands, the Galapagos and _ the 
Sandwich groups, a very great increase has been made, 
especially in the birds. In Borneo and the Philippines 
the increase both in birds and mammals has been even 
more remarkable, while the interesting and very anomalous 
island of Celebes has received special. attention, and has 
been the subject of two very important works—one (in 
English) on the birds by Dr. Meyer of Dresden and the 
late Mr. Wigglesworth, while Drs. Paul and Fritz Sarasin 
are publishing (in German) a work on the whole Biology 
and Geology of the Island, of which four large and finely 
illustrated volumes have already appeared. 


vill PREFACE TO THIRD EDITION 


The lists of the lepidoptera, coleoptera, land and fresh- 
water molluscs, and of flowering plants and mosses, 
supposed to be peculiar to the British Isles, have also 
been corrected and brought up to date by the best 
authorities on these groups, who have kindly given me 
invaluable assistance in this very difficult portion of my 
work. The assistance thus afforded me is in every case 
duly acknowledged in the several chapters here referred to. 

The remaining parts of the work have also been sub- 
jected to careful revision, and the various errors that have 
been pointed out to me or have been detected by myself 
have been corrected. 

The much more extensive lists of species in many of 
the islands have somewhat increased the size of the work, 
but in order to avoid the inconvenience of repaging the 
latter half of the volume, and thus rendering all references 
to this part of it useless for the present edition, the 
numbers of the pages remain, so far as possible, un- 
altered, the additional matter having the letters a, }, ¢, 
&c., appended to the number of the page where the over- 
running begins. This I venture to think will be a great 
convenience to my readers. 


PREFACE TO THE FIRST EDITION 


THE present volume is the result of four years’ additional 
thought and research on the lines laid down in my 
Geographical Distribution of Animals, and may be con- 
sidered as a popular supplement to and completion of that 
work. 

It is, however, at the same time a complete work in 
itself: and, from the mode of treatment adopted, it will, I 
hope, be well calculated to bring before the intelligent 
reader the wide scope and varied interest of this branch of 
natural history. Although some of the earlier chapters 
_ deal with the same questions as my former volumes, they 
are here treated from a different point of view ; and as the 
discussion of them is more elementary and at the same 
time tolerably full, it is hoped that they will prove both 
instructive and interesting. The plan of my larger work 
required that genera only should be taken account of; in 
the present volume I often discuss the distribution of 
species, and this will help to render the work more intelli- 
gible to the unscientific reader. 

The full statement of the scope and object of the present 
essay given in the “Introductory ” chapter, together with 
the “Summary”’ of the whole work and the general view 
of the more important arguments given in the “ Conclu- 
sion,’ render it unnecessary for me to offer any further 
remarks on these points. I may, however, state 


x PREFACE TO FIRST EDITION 


generally that, so far as I am able to judge, a real 
advance has 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, (8) 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 with questions on which they have special 
knowledge, giving me the benefit of valuable emendations 
and suggestions. Mr. Edward R. Alston has looked over 
those parts of the earlier chapters which relate to the 
mammals of Europe and the North Temperate zone ; Mr. 
S. B. J. Skertchley, of the Geological Survey, has read the 
chapters which discuss the glacial epoch and other 
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 
INTRODUCTORY 


Remarkable Contrasts in the Distribution of Animals—Britain and Japan 
—Australia and New Zealand—Bali and Lombok—Floridaand Bahama 
Islands—Brazil and Africa—Borneo, Madagascar, and Celebes— 
Problems in Distribution to be found in every Country—Can be Solved 
only by the Combination of many distinct lines of inquiry, Biological 
and Physical—lIslands offer the best Subjects for the Study of Distribu- 
tion—Outline of the Subjects to be discussed in the Present Volume. 

Pages 3—11 


CHAPTER II 
THE ELEMENTARY FACTS OF DISTRIBUTION. 


Importance of Locality as an Essential Character of Species—Areas of 
Distribution—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 Distribu- 
tion of Orders. } ; ‘ : 5 . Pages 12—30 


xil CONTENTS 


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 
Palearctic Region—Characteristic Features of the Palearctic 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 IV 
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 Scheniclus—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 Abundance of 
Land-shells—The Dispersal of Plants—Special Adaptability of Seeds 
for Dispersal—Birds as Agents in the Dispersal of Seeds—Ocean 
Currents as Agentsin 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 xiii 


Formations ; the Origin of Chalk—Fresh-water and Shore-deposits as 
Proving the Permanence of Continents—Oceanic Islands as Indications 
of the Permanenee of Continents and Oceans—General Stability 
of Continents with Constant Change of Form—Effect of Continental] 
Changes on the Distribution of Animals—Changed Distribution Proved 
by the Extinct Animals of Different Epochs—Summary of Evidence 
for the General Permanence of Continents and Oceans. Pages 83—105 


CHAPTER VII 


CHANGES OF CLIMATE WHICH HAVE INFLUENCED THE DISPERSAL OF 
ORGANISMS : THE GLACIAL EPOCH 


Proofs of the Recent Occurrence of a Glacial Epoch—Moraines—Travelled 
Blocks—Glacial Denosits 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—Paleontological Evidence of Alternate Cold and Warm 
Periods—Evidence of Interglacial Warm Periods on the Continent and 
in North America—Migrations and Extinctions of Organisms Caused 
by the Glacial Epoch : : : . Pages 106—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 the Sun— 
Properties of Air and Water, Snow and Ice, in Relation to Climate— 
Effects of Snow on Climate—High Land and Great Moisture Essential 
to the Initiation of a Glacial Epoch—Perpetual Snow nowhere Exists 
on Lowlands—Conditions Determining the 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 off the Sun’s Heat—South Temperate. Amer’ca as Illustrating 
the Influence of Astronomical Causes on Climate—Geographical Changes 
how far a Cause of Glaciation—Land Acting as a Barrier to Ocean- 
currents—The Theory of Interglacial Periods and their Probable 
Character—Probable 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 Mars as Bearing on the Theory 
of Excentricity as a Cause of Glacial Epochs . . Pages 125—168 


X1V 


Mr. 


CONTENTS 


CHAPTER IX 


ANCIENT GLACIAL EPOCHS, AND MILD CLIMATES IN THE ARCTIC 
REGIONS 


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 Paleozoic 
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 Physical 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 


CONTENTS XV 


“PART II 
INSULAR FAUNAS AND FLORAS 


CHAPTER XI 
THE CLASSIFICATION OF ISLANDS 


es of Islands in the Study of the Distribution of Organisms— 
Classification of Islands with Reference to Distribution—Continental 
Islands—Oceanic Islands . : : : ; . Pages 241—245 


CHAPTER XII 
OCEANIC ISLANDS :—THE AZORES AND BERMUDA 


Tne Azores, or Western 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 the Azorean Fauna and 
mora. ; : , : . Pages 246—262 


Bermuda 


Position and Physical Features—The Red Clay of Bermuda—dZoology of 
Bermuda—Birds of Bermuda—Comparison of the Bird-faunas of Ber- 
muda and the Azores—lInsects of Bermuda—Land Mollusca—Flora of 
Bermuda—Concluding Remarks on the Azores and Bermuda 

Pages 263—274 


CHAPTER XIII 
THE GALAPAGOS 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 Galapagos—Origin of the Flora of the Galapagos 
—Concluding remarks . . . Pages 273—291 


CHAPTER XIV 
ST. HELENA 


Position and Physical Features of St. Helena—Change Effected by Euro- 
pean Occupation—The Insects of St. Helena—Coleoptera—Peculiarities 
and Origin of the Coleoptera of St. Helena—Land-shells of St. Helena 
—Absence of Fresh-water Organisms—Native Vegetation of St. Helena 
—The Relations of the St. Helena be Be Bic per Remarks 
on St. Helena . ; . Pages 292—309 


xvi CONTENTS 


CHAPTER XV 
THE SANDWICH ISLANDS 


Position and Physical Features—Zoology of the Sandwich 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 British Isles—Proofs of Former Elevation—Submerged 
Forests—Buried River Channels—Time of Last Union with the 
Continent—Why Britain is Poor in Species—Peculiar British Birds— 
Fresh-water Fishes—Cause of Great 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 British Flora—Peculiarities of the Irish 
Flora—Peculiar British Mosses and Hepatice—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 Physical Features—General Character of the Fauna of 
Java—Differences 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— 
Mammalia—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 XVil 


CHAPTER XIX 
ANCIENT CONTINENTAL ISLANDS: THE MADAGASCAR GROUP 


Remarks on Ancient Continental Islands—Physical Features of Madagascar 
—Biological Features of Madagascar—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 aSupposed Lemurian Continent—Submerged 
Islands Between Madagascar and India—Concluding Remarks on 
‘* Lemuria ”—The Mascarene Islands—The Comoro Islands—The Sey- 
chelles Archipelago—Birds of the Seychelles—Reptiles and Amphibia— 
Fresh-water Fishes—Land Shells—Mauritius, Bourbon, and Rodriguez 
—Birds—Extinct Birds and their Probable Origin—Reptiles—Flora of 
Madagascar and the Mascarene Islands—Curious Relations of Mascarene 
Plants—Endemic Genera of Mauritius and Seychelles—Fragmentary 
Character of the Mascarene Flora—Flora of Madagascar Allied to that 
of South Africa—Preponderance of Ferns in the Mascarene Flora— 
Concluding Remarks on the Madagascar Group. . . Pages411—449 


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—Peculiarities of 
the Insects of Celebes—Himalayan ‘Types of Birds and Butterflies in 
Celebes—Peculiarities of Shape and Colour of Celebesian Butterflies— 
Concluding Remarks—A ppendix on the Birds of Celebes 

Pages 450—470 


CHAPTER XXI 
ANOMALOUS ISLANDS: NEW ZEALAND 


Position and Physical Features of New Zealand—Zoological Character of 
New Zealand—Mammalia— Wingless Birds Living and Extinct—Recent 
Existence of the Moa—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. . Pages 471—486 


b 


XVili CONTENTS 


CHAPTER XXII 
THE FLORA OF NEW ZEALAND: ITS AFFINITIES AND PROBABLE ORIGIN 


Relations of the New Zealand Flora to that of Australia—General Features 
of the Australian Flora—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—Means by which Plants 
have Migrated from North to South—Newly Moved Soil as Affording 
Temporary Stations to Migrating Plants—Elevation and Depression of 
the Snow-line as Aiding the Migration of Plants—Changes of Climate 
Favourable to Migration—The Migration from North to South has 
been Long going on—Geological Changes as Aiding Migration—Proofs 
of Migration by way of the Andes—Proofs of Migration by way of the 
Himalayas and Southern Asia—Proofs of Migration by way of the 
African Highlands—Supposed Connection of South Africa and Australia 
—The Endemic Genera of Plants in New Zealand—The Absence of 
Southern Types from the Northern Hemisphere—Concluding Remarks 
on the New Zealand and South Temperate Floras . Pages 509—530 


CHAPTER XXIV 
SUMMARY AND CONCLUSION 


The Present Volume is the Development and Application of a Theory— 
Statement of the Biological and Physical Causes of Dispersal—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 Mr. Croll— 
Supposed Limitations of Geological Time—Time Amply Sufficient both 
for Geological and Biological Development—Insular Faunas and Floras 
—The North Atlantic Islands—The Galapagos—St. Helena and the 
Sandwich Islands—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 


Ht, 


12. 


MAPS AND ILLUSTRATIONS 


MAP SHOWING THE DISTRIBUTION OF THE TRUE JAYS 
Frontispiece. 


MAP SHOWING THE ZOOLOGICAL REGIONS. . ... . To face 


MAP SHOWING THE DISTRIBUTION OF PARUS PALUSTRIS 
To face 


A GLACIER WITH MoRAINES (From Sir C. Lyell’s Principles 
SPE AON oi Aor Sve eee 


MAP OF THE ANCIENT RHONE GLACIER (From Sir C. Lyell’s 
Bemveriey of Magy. 2 


DIAGRAM SHOWING THE EFFECTS OF EXCENTRICITY AND 
mamonession ON CLIMATE C-.. o ef oS we ee 


DIAGRAM OF EXCENTRICITY AND PRECESSION 


MAP SHOWING THE EXTENT OF THE NORTH AND SOUTH 
PoLAR IcE 


. DIAGRAM SHOWING CHANGES OF EXCENTRICITY DURING THREE 


WR SE SS eg ee RROD FAG eed leons 2a 
OUTLINE MAP OF THE AZORES 
Map oF BERMUDA AND THE AMERICAN COAST . 


SECTION OF BERMUDA AND ADJACENT SEA-BOTTOM .... 


PAGE 


31 


66 


109 


110 


127 


129 


138 


171 
248 
263 


264 


XX 


13. 


14. 
15. 


16. 
17. 


18. 


19. 


20. 
21. 
22. 
23. 
24. 


25. 


26. 


MAPS AND ILLUSTRATIONS 
MAP OF THE GALAPAGOS AND ADJACENT COASTS OF SOUTH 
CN SE Rie Re ae cary Pre. Sa OCD LP) MEN Dy 4 
RAS TOR THE AIA CAPAC OS ooh med. gh elect we 
Map oF THE SovutTH ATLANTIC, SHOWING POSITION OF ST. 


PPLENA 6 Se eR at a ihe eee a ee 
Mar. or THE SANDWICH ISLANDS (: . 44> . i323 
Map oF THE NorTH PACIFIC, WITH ITS SUBMERGED BANKS . 


MAP SHOWING THE BANK CONNECTING BRITAIN WITH THE 
ConTINwnr: 2.2.60) 2 shel 20% SPCR OS ee eee 


Mar oF BORNEO AND JAVA, SHOWING THE GREAT SUBMARINE 
BANK, OF SOUTH-HASTERN ASIA- —. 37% 205 


Mar Or JePan any PORMOSA | oo. *e) ees 
PHYSICAL SKETCH Map oF MADAGASCAR (From Nature) 

Map OF MADAGASCAR GROUP, SHOWING DEPTHS OF SEA .. 
Ma? oF THE INDIAN OCRAN - 2 22 N° > 

MAP OF CELEBES AND THE SURROUNDING ISLANDS 


MAP SHOWING DEPTHS OF SEA AROUND AUSTRALIA AND NEW 
ZEALAND 


MAP SHOWING THE PROBABLE CONDITION OF AUSTRALIA 
DURING THE CRETACEOUS EPOCH ...-.-. 


PAGE. 


276° 
277 


293 
311 


312 
333 


373 
392 
413 
415 
424 


451 
471 


496 


ISLAND LIFE 


EA 1 


THE DISPERSAL OF ORGANISMS 


ITS PHENOMENA, LAWS, 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 solved 
only by the 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 
pe hedge-sparrows, wrens, wagtails, larks, redbreasts, 
B 2 


4 ISLAND LIFE PART I 


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 EKurope. 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 m 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 1s all changed, 
and no gum-tree, or wattle, or grass-tree meets the 
traveller's eye. 

But there are some more striking cases even tha, 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 wnlike 
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 
mag?pie-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 Bali. Many of the kingfishers, crow- 
shrikes, and other birds, though of the same general form, 
are of very distinct species; and though a considerable 
number of birds are the same in both islands the difference 


CHAP. I INTRODUCTORY 5 


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 we find equally striking 
examples. The Eastern United States possess very 
peculiar and interesting plants and animals, the vegetation 
becoming more luxuriant as we go south but not altering 
in essential character, so that when we reach 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. Butif 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 
change is most striking, 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 


1 A small number of species belonging to the West Indies are found in 
the extreme southern portion of the Florida Peninsula. 


6 ISLAND LIFE - PART 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 Australia, correspond 
closely in climate; yet the birds and quadrupeds of these 
three districts are as completely unlike each other 4s 
those of any parts of the world that can be named. 

If we visit the great islands of the globe, we find that 
they present similar anomalies in their animal productions, 
for while some exactly resemble the nearest continents 
others are widely different. Thus the quadrupeds, birds 
and insects of Borneo correspond very closely to those 
of the Asiatic continent, while those of Madagascar are 
extremely unlike African forms, 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—we 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 


CHAP. I INTRODUCTORY 4 


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 there and others 
are not there, a problem which involves all the migrations 
of these species and their ancestral forms—all the 
vicissitudes of climate and all the changes of sea 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, imorganic 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 flora of the whole world, and even 
a detailed knowledge of many parts of it, including the 
islands of more special interest and their adjacent. 
continents. This kind of knowledge is of very slow growth, 
and is still very imperfect ;' and in many cases it can 


1 T 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 and again, often 
described several times over under new names, and not unfrequently 
stated to be from places they never inhabited. The result of this wretched 
system is that the productions of some of the most frequently visited and 
most interesting islands on the globe are still very imperfectly known, 
while their native plants and animals are being yearly exterminated, and 
this is the case even with countries under the rule or protection of 


8 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 could be arrived 
at or even conceived ; for if each species was created where 
it is now found no further inquiry can take us beyond 
that fact, and there is an end of the whole matter. 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 
eroups.!| 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 Mauritius, St. Helena, and several others, have only been 
adequately explored after an important portion of their productions has 
been destroyed by cultivation or the reckless introduction of goats and 
pigs. The employment in each of our possessions, and those of other 
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. 

1 The general facts of Paleontology, as bearing on the migrations of 
animal groups, are summarised in my Geographical Distribution of Animals, 
Vol. I. Chapters VI., VIT., and VIlT. 


CHAP. I INTRODUCTORY. 9 


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 
diminishing 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 affordmg 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 | 


; 
Ps 


questions in geographical biology—the origin of the fauna | 


and flora of New Zealand. 

Such are the various classes of evidence that bear 
directly on the question of the distribution of organisms; 
but there are others of even a more fundamental character, 
and the importance of which is only now 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 continents and oceans. If glacial epochs in temperate 
lands and mild climates near the poles have, as now 
believed by men of eminence, occurred several times over 
in the past history of the earth, the effects of such great 
and repeated changes, both on the migration, modification, 
and extinction, of species, must have been of overwhelming 
importance—of more importance perhaps than even the 
geological changes of sea and land. It is therefore neces~ 
sary to consider the evidence for these climatal changes ; 


ct 


10 ISLAND LIFE, PART I 


and then, by a critical examination of their possible causes, 
to ascertain whether they were isolated phenomena, were 
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 which 
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 gontinents 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 we 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 earth 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 consisted 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 


CHAP. 11 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 diversitres 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 
theory, 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 Distribution.—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. Hach species is moreover usually 
limited to one continuous area, over the whole of which itis 
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 
Kurope and Asia beyond lat. 55°, and also in Scotland and 
Treland. 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 ISLAND LIFE PART I 


continuous distribution of a species, 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. 

Lxtent and Inmitations of Specific Areas—Leaving for 
the present these cases of want of continuity in a species, 
we 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. Amon 
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 


i ee. aie 


omar. 11 THE ELEMENTARY FACTS OF DISTRIBUTION 15 


as Pekin, and even extends into tropical Africa, thus 
rivalling the leopard and the wolf in the extent of country 
it occupies. 

Of very restricted ranges there are many examples, but 
some of these are subject to doubts as to the distinctness 
of the species or as to its geographical limits being really 
known. In Europe we have a distinct species of ibex 
(Capra Pyrenawa) confined to the Pyrenean mountains, 
while the true marmot is restricted to the Alpine range. 
More remarkable is the Pyrenean water-mole (Mygale 
Pyrenaica), a curious small insectivorous animal found only 
in a few places in the northern valleys of the Pyrenees, 
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 apparent obstacle to their wider extension. 

Specific range of Birds—Among birds we find instances 
of much wider range of species, which is only what might 
be expected considering their powers of flight ; but, what 
is very curious, we also find more striking (though 
perhaps not more frequent) examples of extreme limita- 
tion of range among birds than among mammals. Of the 
former phenomenon 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 
borealis) 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 (Cyanopica cook?) 
confined to the central portions of the Spanish peninsula ; 
and the Italian sparrow found only in Italy and Corsica, 


16 ISLAND LIFE PART I 
In Asia, Palestine affords some examples of birds of very 
restricted range—a beautiful sun-bird (Wectarinea osea) a 
peculiar starling (Amydrus tristramit) 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 Veragua has a species con- 
fined to its wooded crater. One of the most strange and 
beautiful of the humming-birds (Loddigesia mirabilis) 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 !! 

The 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 


1 Since these lines were written, 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.) 


oar. 1 THE ELEMENTARY FACTS OF DISTRIBUTION 17 


more are restricted to the east, the centre, or the west, 
respectively. | 

Generic Areas,—Having thus obtained a tolerably clear 
idea of the main facts as to the distribution of isolated 
species, let us now consider those collections of closely- 
allied species termed genera. What a genus is will be 
sufficiently understood by a few illustrations. All the 
different kinds of dogs, jackals, and wolves belong to the 
dog genus, Canis; the tiger, lion, leopard, Jaguar, and the 
wild cats, to the cat genus, Felis; the blackbird, song-thrush, 
missel-thrush, fieldfare, and many others to the thrush 
genus, Turdus; the crow, rook, raven, and jackdaw, to the 
crow genus, Corvus; but the magpie belongs to another, 
though closely-allie¢ 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 ina 
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 Overlapping Areas.—The species of a genus 
are distributed in two ways. Hither they occupy distinct 
areas which do not touch each other and are sometimes 
widely separated, or they touch and occasionally overlap 

* Many of these large genera are now subdivided, the divisions being 
sometimes termed genera, sometimes sub-genera. 


C 


18 ISLAND LIFE PART I 


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 (Pithecia monachus 2) 
comes up to the south bank of the Upper Amazon, while 
immediately we cross over to the north bank we find 
another species (Pithecia rufibarbata?). Among birds we 
have the green jacamar (Galbula viridis), abundant on the 
north bank of the Lower Amazon, while on the south 
bank we have two allied species (Galbula rufoviridis and 
G. cyanercollis) ; and among insects we have at Santarem 
on the south bank of the Amazon, the beautiful blue 
butterfly, Callithea sapphira, while almost opposite to it, at 
Monte-alegre, an allied species, Callithea Lepriewrt 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 


oHaP. 1 THE ELEMENTARY FACTS OF DISTRIBUTION 19 


species extending over a considerable portion of the area 
occupied by the genus and including the entire areas of 
some of the other species. So little has been done to 
work out accurately the limits of species that it is very 
difficult to give examples. One of the best is to be found 
in the genus Dendreca, 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, D. dominica comes as far as 
the middle Eastern States, D. cwrulea keeps west of the 
Alleghanies, D. discolor 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. 
—IJn 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 (Parus 
major) has the widest range of all, extending from the 
Arctic circle to Algeria, Palestine, and Persia, and from 
Treland 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 
ater) which inhabits all Europe from the Mediterranean 
to about 64° N. latitude, in Asia Minor to the Lebanon 
and Caucasus, and across Siberia to Amoorland and Japan. 
The marsh tit (Parus palustris) inhabits temperate and 
south Kurope 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 borealis), 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 camtschatkensis) ranges from North-eastern 
Russia across Northern Siberia to Lake Baikal and to 
Hakodadi in Japan, thus overlapping Parus borealis in the 


G2 


20 ISLAND LIFE PART I 


western portion of its area. Our little favourite, the blue 
tit (Parus ceruleus) ranges over all Europe from the 
Arctic circle to the Mediterranean, and on to Asia Minor 
and Persia, but does not seem to pass beyond the Ural 
mountains. Its lovely eastern ally the azure tit (Parus 
cyaneus) overlaps the range of P. cwruleus in Western 
Kurope 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. Parus 
tenerifie, a beautiful dark blue form of our blue tit, inhabits 
North-west Africa and the Canaries; Parus ledouci, closely 
allied to our coal tit, is found only in Algeria; Parus 
lugubris, allied to the marsh tit, is confined to South-east 
Kurope and Asia Minor, from Hungary and South Russia 
to Palestine; and Parus cinctus, 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 there 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 


cHAP. 11 THE ELEMENTARY FACTS OF DISTRIBUTION 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 Palearctic ! 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 map 
which forms the frontispiece to this volume. 

1. Garrulus glandarius—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 cervicalis—The Algerian jay, is a very 
distinct species inhabiting a limited area in North Africa, 
and found in some places along with the common species. 

3. Garrulus krynickt.—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 atricapillus.—The Syrian jay, is very closely 
allied to the last, and inhabits an adjoining area in Syria, 
Palestine, and Southern Persia. 

5. Garrulus hy yreanus.—The Persian jay, is a_ small 
species allied to our jay and only known from the Elburz 
Mountains in the north of Persia. 

6. Garrulus brandit.—Brandt’s jay, 1s a very distinct 
species, having an extensive range across Asia from the 
Ural Mountains to North China, Mandchuria, and the 
northern island of Japan, and also crossing the Urals into 


1 The Palearctic region includes temperate Asia and Europe, as wil] be 
explained in the next chapter. 


22, ISLAND LIFE PART I 


Russia where it has been found as far west as Kazan in 
districts where the common jay also occurs. 

7. Garrulus lanceolatus—The black-throated jay, is a 
very distinct form known only from the North-western 
Himalayas and Nepal, common about Simla, and extend- 
ing into Cashmere beyond the range of the next species. 

8. Garrulus bispecularis—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 
Abbé David it reaches Moupin in East Thibet. | 

9. Garrulus sinensis—The Chinese jay, is very closely 
allied to the Himalayan, of which it is sometimes classed 
as a sub-species. It seems to be found in all the southern 
mountains of China, from Foochow on the east to Sze-chuen 
and East Thibet on the west, as it is recorded from Mou- 
pin by the Abbé David as well as the Himalayan bird—a 
tolerable proof that it is a distinct form. 

10. Garrulus tawanus.——The Formosan jay 1s a very 
close ally of the preceding, confined to the island of 
Formosa. , 

11. Garrulus japonicus—The Japanese 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 

enus. According to Mr. Seebohm this species is equally 
allied to the Chinese and Siberian jays. 

In the accompanying map (see frontispiece) we have laid 
down the distribution of each species so far as it can be 
ascertained from the works of Sharpe and Dresser for 
Europe, Jerdon for India, Swinhoe for China, and 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. 1 THE ELEMENTARY FACTS OF DISTRIBUTION 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 European G. 
glandarius and the Asiatic G. Br andti, The former has 
three species overlapping 1t—in Algeria, in South-eastern 
and North-eastern Europe respectively. The Syrian jay 
(No. 4), 1s not known to occur anywhere with the black- 
headed jay (No. 3), and perhaps the two areas do not meet, 
The Persian jay (No, 5), is quite isolated. The Himalayan 
and Chinese jays (Nos. 7, 8, and 9) form a group which 
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 PART I 


that of the blue magpies, forming the genus Cyanopica. 
One species (C. cookt) is confined (as already stated) to the 
wooded and mountainous districts of Spain and Portugal, | 
while the only other species of the genus (C. cyanus) is 
found far away in 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 JM. 
muscovitica, being found only on the banks of the Volga 
and Don in South-eastern Russia, while the other, J/. 
pyrenaica, 18 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. tricarunculatus 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, rmging notes, like a bell 
or a blow on an anvil, as well as for their peculiar colours. 
They are therefore known 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 
home, is afforded by the snow-partridges of the genus 
Tetraogallus. One species inhabits the Caucasus range 
and nowhere else, keeping to the higher slopes from 6,000 
to 11,000 feet above the sea, and accompanying the ibex in 
its wanderings, as both feed on the same plants. Another 


UNS ed bas 
eS Saag 
; 


cHAP. 11 THE ELEMENTARY FACTS OF DISTRIBUTION 25 


has a wider range in Asia Minor and 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 
which the species of one genus are separated in remote 
continents or islands. The most striking of these is that 
of the tapirs, forming the genus Tapirus, of which there 
are two or three species in South America, and one very 
distinct species in Malacca and Borneo, separated by 
nearly half the circumference of the globe. Another 
example among quadrupeds is a peculiar genus of moles 
named Urotrichus, of which one species inhabits Japan 
and the other British Columbia. The cuckoo-like honey- 
guides, forming the genus Indicator, are tolerably 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 Cochoa, have two 
species in the Eastern Himalayas and Eastern China, 
while the third is confined to Java; the curious genus 
Kupetes, supposed to be allied to the dippers, has one 
species in Sumatra and Malacca, while four other species 
are found two thousand miles distant in New Quinea; 
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 Distribution —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. 7 


26 ISLAND LIFE PART I 


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° 8, 
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 Kast 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 family 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. 


 onap.-11 THE ELEMENTARY FACTS OF DISTRIBUTION 27 


We must therefore consider them somewhat more 
fully. 

Among mammalia the most remarkable of these divided 
families is that of the camels, of which one genus 
Camelus, 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 
high 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 twocontinents, 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 Centetide, 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 well as the 
Atlantic ocean separating allied genera. ‘Two families (or 
subfamilies) of rat-like animals, Octodontide and 
Hchimyide, are also divided by the Atlantic. Both are 
mainly South American, but the former has two genera in 
North and East Africa, and the latter also two in South 
and West Africa. Two other families of mammalia, 
though confined to the Eastern hemisphere, are yet 
markedly discontinuous. The Tragulidze are small deer- 
like animals, known as _ chevrotains or mouse-deer, 
abundant in India and the larger Malay islands and 
forming the genus Tragulus; while another genus, 
Hyomoschus, is confined to West Africa. The other 
family isthe Simiide 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 Echimyidze and other rodents 
of Africa and South America. 

Among birds and reptiles we have several families, 
which, from being found only within the tropics of Asia, 
Africa, and America, have been termed tropicopolitan 
groups. The Megalemide or barbets are gaily coloured 


28 ISLAND LIFE Panes 


fruit-eating birds, almost equally abundant in tropical Asia 
and Africa, but less plentiful in America, where they 
probably suffer from the competition of the larger sized 
toucans. The genera of each country are distinct, but all 
are closely allied, the family being a very 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 we have two families of snakes—the 
Dendrophide or tree-snakes, and the Dryiophide or green 
whip-snakes—which are also found in the three tropical 
regions of Asia, Africa, and America, but in these cases 
even some of the genera are common to Asia and Africa, 
or to Africa and America. The lizards forming the family 
Amphisbeenide 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 Ceeciliade are tropicopolitan, as are also the 
toads of the family Engystomatide. Insects also furnish 
some analogous cases, three genera of Cicindelide, 
(Pogonostoma, Ctenostoma, and Peridexia) showing a 
decided connection between this family in South America 
and Madagascar; while the beautiful family of diurnal 
moths, Uraniide, is confined to the same two countries. 
A somewhat similar but better known illustration 1s 
afforded by the two genera of ostriches, one confined to 
Africa and Arabia, the other to the plaims of temperate 
South America. 

General features of Overlapping and Discontinuous 
Areas.—These numerous examples of discontinuous genera 
and families form an important section of the facts of 
animal dispersal which 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 grade imperceptibly into those cases of conter- 
minous and overlapping areas which we have seen to 


ent 


-onap. 11 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 (Sylviadz) 
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 Cebidze 
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 Bovide, 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. 


Restricted Areas of Famlies—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 which a family 
contains numerous species and sometimes even several 
genera, and yet is confined to a narrow area. Such are 
the golden moles (Chrysochloride) consisting of two 
genera and three species, confined to extratropical South 
Africa ; the hill-tits (Liotrichidz), a family of numerous 
genera and species mainly confined to the Himalayas, but 
with a few straggling species in the Malay countries and 
the mountains of China; the Pteroptochide, large wren- 
like birds, consisting of eight genera and nineteen species, 
almost entirely confined to temperate South America and 


30 ISLAND LIFE PART I 


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 Kast Australia. Among reptiles the 
most striking case of restriction is that of the rough-tailed 
burrowing snakes (Uropeltidze), the five genera and 
eighteen species being strictly confined to Ceylon and the 
southern parts of the Indian Peninsula. 

The Distribution 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 well-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. 


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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 
Palearctic Region—Characteristic features of the Palearctic 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. 


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 
“Kurope” will not give, with any approach to accuracy, 
the range of any one genus of mammals or birds, and 


82 ISLAND LIFE PART I 


perhaps not that of half-a-dozen species. Hither 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 Europe. 
There are, indeed, a few species limited to Central or 
Western or Southern Europe, and these are almost the 
only cases in which we can use the word for zoological 
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 Asia, 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 the northern 
continent. 

It being thus clear that the old and popular divisions 
of the globe are very inconvenient when used to describe 
the range of animals, we are naturally led to ask whether 
any other division can be made which will be more useful, 
and will serve to group together a considerable number of 
the facts we have to deal with. Such a division was made 
by Mr. P. L. Sclater more than twenty years ago, and it 
has, with some slight modifications, come into pretty 
general use in this country, and to some extent also 


CHAP. Iil ZOOLOGICAL REGIONS 33 


abroad; we shall therefore proceed to explain its nature 
-and the principles on which it is established, as it will 
have to be often referred to in future chapters of this work, 
and will take the place of the old geographical divisions 
whose 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 Range of British Mammals as indicating a Zoological 
Region.—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 : 


Pend Cat ,........ Lurope | N. Africa | Siberia, Afghanistan. 
ae Europe | N. Africa | Central Asia to Amoor. 
Ber w casel .....,...... Europe | N. Africa | Central Asia to Amoor, 
BUOEPIEEE ..............- Europe | N. Africa | Siberia. 
Masadcer ........,... Europe | N. Africa | Central Asia to Amoor. 
eee Europe | N. Africa | Central Asia to Amoor. 
7. Hedgehog......... Europe — Central Asia to Amoor. 
MIG. 2... so. 0s0.-5. Europe — Central Asia, 
eemduitrel............ Europe — Central Asia to Amoor, 
20, Dormouse......... Kurope — — 
Ti. Water-rat......... Europe — Central Asia to Amoor. 
ae Europe — W. Siberia, Persia. 
MeeHAODIL ............ Europe | N. 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 


D 


34 ISLAND LIFE PARTI 


more arctic kinds, as already stated, extend into the colder 
regions of North America. : 

Range of Hast 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, we may treat 
all these as really Kuropean, 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 Huropean 
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 
Kuropean and West Asiatic elements in the mammalia 
which inhabit the district. 

The Range of British Birds —As it 1s very important 
that no doubt should exist as to the limits of the zoological 


“a SO 


OE Ee’ — 


itt 


a 


‘) 
lg 


CHAP. HII ZOOLOGICAL REGIONS 35 


region of which Europe forms a part, we will now examine 
the birds, in order to see how far they agree in their 
distribution with the mammalia. Of late years great 
attention has been paid to the distribution of European 
and Asiatic birds, many ornithologists having travelled in 
North Africa, in Palestine, in Asia Minor, in Persia, in 
‘Siberia, in Mongolia, and in China; so that we are now 
able to determine the exact ranges of many species in a 
manner that would have been impossible a few years ago. 
These ranges are given for all British species in the new 
edition of Yarrell’s History of British Birds 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 BrrpDs wHIcH FXTEND To NortrH AFRICA AND CENTRAL 
oR NorTH-EAST ASIA. 
MEMEEIRTIEE COULILTIO .........0.000 Red backed Shrike (also all Africa). 
Ber tOlts GaLDUIA ...........000 Golden Oriole (also all Africa). 
Mane 7S TUSICUS .............4. Song-Thrush, 
4, eee Red-wing. 
5. Ot Fieldfare. 
6. Monticola saxatilis............ Blue rock Thrush. 
MePTHTICIILG SUCCICA............... Bluethroat (also India in winter). 
8. Saxicola rubicola ............ Stonechat (also India in winter). 
9. ye a Wheatear (also N. America). — 
10. Acrocephalus arundinaccus. Great Reed-Warbler. © 
MEENLIG CUTYUCA ............... Lesser Whitethroat. 
MPTUS IAIOT .............0..5. Great Titmouse. 
13. Motacilla sulphurca ......... Grey Wagtail (also China and Malaya). 
14, -y a Yellow Wagtail. 
BeeaMehUs (77ViGIis............... Tree Pipit. 
16. NT Water Pipit. 
‘ae Penn CSETIS ............ Tawny Pipit. 
18. Alauda arvensis............... Skylark. 
19. 0 Crested Lark, 


SOONAMNE Whore 


ne 


ISLAND LIFE PART I 


. Emberiza scheniclus ......... Reed Bunting. 


' . CEPINOUG 8... Yellow-hammer. 
2. Fringilla montifringilla ... Brambling. 
PE SSCT INOTMORUS “3... cxaeass Tree Sparrow (also S. Asia), 
55. *LOMCSELCUS” 5 Sun tyke House Sparrow. 
. Coccothraustes vulgaris ...... Hawfinch. 
 CaTdtelis SPINUs:  ee05..2c Siskin (also China), 
fo LOG CURVITOSTE. cote. cee Crossbill. 
» SEUPNUS VULYATIS 6.2... 02004- Starling. 
. Pyrrhocorax graculus ...... Chough. 
eC OT OUS LOPONE 0» Solak aac s ss Crow. 
IT URGO .TUSTIOD 205) erccs aves Swallow (all Africa and Asia). 
Cotile T1OU7UE... xian cis en ds Sand Martin (also India and N. America) 


BrITIsH BIRDS WHICH RANGE TO CENTRAL OR NORTH-EAST ASIA. 


«| Dantes ceewbator, .. 62.553 ives Great Grey Shrike. 
ss, a UP US- COT CUE us chan s see8 White’s Thrush (also to Japan), 
: 5 OP LPULOPTS 3 2 2. S85 Black-throated Thrush. 
. Acrocephalus nevius ......... Grasshopper Warbler. 
. Phylloscopus superciliosus... Yellow-browed Warbler. 
» Certhia familiaris ............ Tree-creeper. 
th OPUS CUCPINCUS KT. n chee. et: Blue Titmouse. 
gt Cee tach osiencweriee cuaets Coal Titmouse. 

TA i) ig eee a Marsh Titmouse. 
. Acredula caudata ............ Long-tailed Titmouse. 
. Ampelis garrulus ............ Wax-wing. 
~ Anthas TUChGArAL... 03.255 6..0s Richard’s Pipit. 
5 sO QUESTS eos ioe Shore Lark (also N. America), | 
. Plectrophanes nivalis......... Snow-Bunting (also N. America). | 

of lapponicus ... Lapland Bunting. 
. LEmbertiza rustica ..........5 Rustic Bunting (also China). 
: = DUSUE  wxcsieenees Little Bunting. 
LOCO VIMOTED. 55. co kelvin Mealy Redpole (also N. America). 
. Pyrrhula erythrina ......... Scarlet Grosbeak (also N. India, China), 

bY LS a Pine Grosbeak (also N. America). 

=» LODE DIF ASOTUNE:. isis Two-barred Crossbill. 
i TOOT TOIOME igo tae Rose-coloured Starling (also India). 
OP OUS LOVGE 6 yo. adits vas eee Raven (also N. America), 
Be gn i A a ee Magpie. 
. Nucifraga caryocatactes...... Nutcracker. 


III. British BIRDS RANGING INTO N. AFRICA AND W. ASIA. 


TOUS TREMOR AN es os das be Lesser Grey Shrike. 
55 CMT TORIAEUS See Woodchat (also Tropical Africa). 
. Muscicapa grisola 3.6.0.2 .64 Spotted Flycatcher (also E. and S. 
Africa). 
2. atricapilla ...... Pied Flycatcher (also Central Africa). 
Pirdats viscev0rv us 20. fans. Mistletoe-Thrush (N. India in winter). 
a ga) Mee RR oe Blackbird. 
ey. LONGING 2. 5 Pere Ring Ouzel. 
. Accentor modularis ......... Hedge Sparrow. 
. Hrithacus rubecula............ Redbreast. 
. Danttias tuscinia. .....%eccs. Nightingale. 


ad 
ey 
{ 
— 
Sax" 
‘i a 


CHAP. III ZOOLOGICAL REGIONS 37 
‘ll. Ruticilla phenicurus......... Redstart. 
a2. HA | ORES nee ae Black Redstart. 
Bee axricola Twdetra.........00 .. Whinchat. 
Seesedon galactodcs .........05. Rufous Warbler. 
15. Acrocephalus streperus ...... Reed Warbler. 
16. is scheenobenus... Sedge Warbler. 
17. Melizophilus undatus ...... Dartford Warbler. 
SO Greater Whitethroat. 
CT Sr Garden Warbler. 
Mee y aricapilia ............ Blackcap. 
BS | OPDREG, ..... 0... essences Orphean Warbler. 
22. Phylloscopus sibilatrix ....... Wood Wren. 
23. a trochzlus...... Willow Wren. 
24. “ne collybita ...... Chiffchaff. 
25. Regulus cristatus ............ Golden-crested Wren. 
26. oe agnicapilius ......... Fire-crested Wren. 
27. Troglodytes parvulus......... Wren, 
ON ee Nuthatch. 
Meemoracilia alba................. White Wagtail (also W. Africa), 
30. - a eee Blue-headed Wagtail. 
31. Anthus pratensis ............ Meadow-Pipit. 
EA IGUAG ATDOTCE .........00040 Woodlark. 
33. Calandrella brachydactyla.. Short-toed Lark. 
34. Emberiza miliaria............ Common Bunting. 
35. " ne ee Cirl Bunting. 
36. sa hortulana ......... Ortolan. 
Beerringiiid celebs ............... Chaffinch. 
38. Coccothraustes chlori:......... Greenfinch. 
39. Serinus hortulanus ......... Serin. 
40. Carduelis elegans ............ Goldfinch. 
41. Linota cannabina ............ Linnet. 
49. Corvus monedula ............ Jackdaw. 
Me CIIHON UTDICH .............. House-Martin. 

IV. British Brrps RANGING TO NorTH AFRICA. 
IEIOLLES TCLETUNG, ... cus cccvecsencscecceses Icterine Warbler. 
DRECPOCCDIVGINS AYUWALICUS ...... 2... ccsecceenee Aquatic Warbler. 
3. < PSIIOULEE 2. coci see. Hund’ Savi’s Warbler. 
MEOIECUILCE LULGUDTIS 2.0.0... scene eteneeeneens Pied Wagiail. 
PT AALLE CUTODOCD .....0cccccceccenctsccseees Bullfinch. 

EN TIEGIILLUS QUANAATIUS ...........ccseenseeeees Jay. 

Y. British Birps RANGING TO WeEsr ASIA ONLY. 
Meetccentor collaris............ Alpine Accentor. 
2. Muscicapa parva ......... Red-breasted Flycatcher (to N. W India). 
3. Panurus biarmicus ...... Bearded Titmouse. 
4. Melanocorypha sibirica... White-winged Lark. 
5. Huspiza melanocephala... Black-headed Bunting. 
6. Linota flavirostris ......... Twite 
7. Corvus frugilegus ......... Rook 
VI. British BIRDS CONFINED TO EUROPE. 

1. Cinclus aquaticus............64. Dipper (closely allied races inhabit other 


; parts of the Palearctic Region). 
UE APPS CTUSLALUS ... 0. .ccayes hes ... Crested Titmouse, 


nN 


38 ISLAND LIFE PARTI 


D: ARIUS ODSCUTUS o.oo. vacy ensue Rock Pipit. 

A, TAME PUPSESCOENS 26). cdeavcaese Lesser Redpoll (closely allied races in 
N. Asia and N. America). 

5, Loxia pityopsittacws.........65. Parrot Crossbill (a closely allied form in 
N. Asia). 


We find, that out of a total of 118 British Passeres. 


there are: 


32 species which range to North Africa and Central 


or Kast 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. | 3 

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 Asvan Birds,—To complete the evidence 
we only require to know that the Hast 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 Hastern — 
Siberia have been carefully studied by Russian naturalists — 
and afford us the means of making the required comparison, — 


There are 151 species belonging to the orders Passeres and 


Picarize (the perching and climbing birds), and of these no ~ 
less than 77, or more than half, are absolutely identical — 


a ee eS ee eee oe ee, ee 


OHAP. IIT ZOOLOGICAL REGIONS © 39 


with European species; 63 are peculiar to North Asia, but 
all except five or six of these are allied to Kuropean 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 
“Palearctic’’ by Mr. Sclater, meaning the “northern 
old-world” region—a name now well known to naturalists. 

The Limits of the Palearctic 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 ina 
few places, its limits can only be approximately defined. 
On the north, east, and west it extends to the ocean, and 
includes a number of islands whose peculiarities will be 
pointed out in a subsequent chapter ; so that the southern 
boundary alone remains, but as this runs across the entire 
continent from the Atlantic to the Pacific ocean, often 
traversing little-known regions, we may perhaps never be 
able to determine it accurately, even if it admits of such 
determination. In drawing the boundary line across 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 Palearctic 
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 Palearctic region, and Baluchistan should 
probably go with these. The boundary in the north- 


western part of India is again difficult to determine, but it 


40 ISLAND LIFE PART I 


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, perhaps, 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, while the 
northern forms visit every part of China in winter. From 
what we know, however, of the distribution of some of the 
more typical northern and southern species, we are able to 
fix the limits of the Palearctic 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 


CHAP. III ZOOLOGICAL REGIONS 41 


China and East Thibet in about 32° N. latitude; where, at 
Moupin, a French missionary, Pére David, made extensive 
collections showing this district to be at the junction of 
the tropical and temperate faunas. Japan, as a whole, is 
decidedly Palzearctic, 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 Palearctic Region.—Having 
thus demonstrated the unity of the Palzarctic region by 
tracing out the distribution of a large proportion 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 afew 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 Talpide or 
moles, the family being confined to the Palearctic 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 Bovide, chiefly antelopes ; 
while the entire group of goats and sheep, comprising 
twenty-two species, is almost confined to it, one species 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 which the bull- 
finches (Pyrrhula) and the buntings (Emberiza) are the 


42 ISLAND LIFE 7 PART 1 


ee 


most important. The true pheasants (Phasianus) are 
wholly Palzearctic, 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 Palzarctic 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-water 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 elsewhere 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 we 
can only now refer to the great family of Carabidee, or 
predaceous ground-beetles, which are immensely numerous 
in this region, there being about fifty peculiar genera ; while 
the large and handsome genus Carabus, with its allies Pro- 
cerus and Procrustes, containing nearly 300 species, 1s almost 
wholly confined to this region, and would alone serve to dis- 
tinguish it zoologically from all other parts of the globe. 

1 The following list of the genera of reptiles and amphibia peculiar to 


the Palearctic Region has been furnished me by Mr. G. A. Boulenger, of 
the British Museum :— 


SNAKES. Frogs AND TOoADs. 
Achalinus—China, Japan. A ye Re are S.W. Asia. 

Piet ) clodytes—W. Europe. 
ere nae ara agai Discoglossus—S. mite N.W.At 
Macroprotodon—S. Eur., N. Af. Bombinator—Eur., Temp. Asia, 
Taphrometopon—Cent. Asia. Alytws—Cent, and W. Kur. 

NeEwTs. 
LIZARDS. Salamandra—Eur., ‘N. Af., S.W. 
Phrynocephalus—Cent. and S.W. Asia. 

Asia. Chioglossa—Spain and Portugal. 
Anguis—Europe, W. Asia. Salamandrina—Italy. 
Blanus—S.W. Eur., N.W. Africa, Pachytriton—East Thibet. 

S.W. Asia. Hynobius—China and Japan. 
Trogonophis—N.W. Africa. Gcomolge—K. Manchuria. 


-Lacerta—Eur. Temp. Asia, N. Onychodactylus—Japan. 
Africa (one sp. in Sdalamandrella—Siberia. 


AN, BT). Ranidens—Siberia. 
Psammodromus—S.W. Eur., N.W.  Batrachyperus—East Thibet. 
Africa. Myalobatrachus—China, Japan. 


Algiroides—S, Eur, Protews—Caverns of 8, Austria. 


ie ee i - © ee eee, wee eo - 


, CHAP. III ZOOLOGICAL REGIONS 43 


Having given so full an exposition of the facts which 
determine the extent and boundaries of the Palearctic 
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 Palzearctic region. 

Taking first the mammalia, we find the following re- 
markable animals at once separating 1t from the Palsearctic 
and every other region. The gorilla and chimpanzee, the 
baboons, numerous lemurs, the spotted hyzena, the aard- 
wolf and hyzna-dog, zebras, the hippopotamus, giraffe, 
and more than seventy peculiar antelopes. Here we have 
a wonderful collection of large and peculiar quadrupeds, 
but the Ethiopian region is also characterised by the 
absence of others which are not only abundant in the 
Palearctic 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 distiact as to constitute 
a new family, Potamogalide; the goldenmoles, also 
forming a peculiar family, Chrysochloride; as do the 
elephant-shrews, Macroscelidide ; the singular aard-varks, 
or earth-pigs, forming a peculiar family of Edentata called 
Orycteropodide ; while there are numerous peculiar genera 
of monkeys, swine, civets, and rodents. 

Among birds the most conspicuous and remarkable are, 
the great-billed vulture-crows (Corvultur), the long-tailed 


44 ISLAND LIFE PART I 


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 (Balzeniceps), and the 
true ostriches. There are also three quite peculiar 
African families, the Musophagide or plantain-eaters, 
including the elegant crested touracos; the curious 
little finch-like colies (Coliidz), and the Inrrisoride, 
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 
Cetoniide; and some of the Achatine, which are the 
largest of all known land-shells. 

Definition and Characteristic Groups of the Griental 
fegion.—The Oriental region comprises all Asia south of 
the Palzearctic 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 orang-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 (Timalide), its beautiful little hill-tits (Liotrich- 
idee), its green bulbuls (Phyllornithidz), its many varieties 


oe 


CHAP. III 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 Phasianide, comprising the peacocks, 
argus-pheasants, fire-backed pheasants, and jungle-fowl. 
Many of these are, it is true, absent from the peninsula 
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, 1s 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 green bird (Gallus 
gneus 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 PART I 


ficent golden and green Papilionide 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 Carabide, while the 
catoxantha is equally a giant among the Buprestidae. On 
the whole, the insects of this region probably surpass 
those of any other part of the world, except South America, 
in size, varicty, and beauty. 

Definition and Characteristie Groups 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 


1 Remains of the dingo have been found fossil in Pleistocene deposits but 
the antiquity of man in Australia is not known. It is not, however, 1m- 


‘ 
’ 
- 
q 


a ; 


SP OHAP, III ZOOLOGICAL REGIONS 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 region ; but this 
question need not now delay us. 

In birds Australia is by no means so isolated from the 
rest of the world, as it contains great numbers of warblers; 
thrushes, 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- 
phagidee), 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 asin Europe. My friend A. C. Swinton, 
Esq., while working in the then almost unknown gold-field 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 fine-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 
ofan 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. Mackworth Shore, one of 
the discoverers of the gold-field, before any rush to it had taken place, and 
it seems impossible to avoid the conclusion that it was formed prior to the 
deposit of the gravel drift and iron-stained sandstone under which it lay. 
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. 


4 
a 

ra 
¥ 

Ss 

, i 

a 


48 ISLAND LIFE PART I 


never sit upon their eggs, but allow them to be hatched, 
reptile-lke, 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 Groups of the Nearetre 
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 poimt 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 Palearctic 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 Paleearctic. K 

At first sight the mammalia of North America do not — 
seem to differ much from those of Hurope or Northern | 
Asia. There are cats, lynxes, wolves and foxes, weasels, — 
bears, elk and deer, voles, beavers, squirrels, marmots, and — 


; 


CHAP. III 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 (Mephitis), 
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 antelope (Antilocapra) 
and the mountain goat of the trappers (Aplocerus), both 
peculiar genera. Coming to the rodents we find that the 
mice of America differ in some dental peculiarities from 
those of the rest of the world, and thus form several 
distinct genera; the jumping mouse (Xapus) is a peculiar 
form of the jerboa family, and then we come to the 
pouched rats (Geomyidz), 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 the old. 

We must add to these peculiarities some remarkable 
deficiencies. The Nearctic region has no hedgehogs, nor 
wild pigs, nor dormice, and only one wild sheep in the 
Rocky Mountains as against twenty species of sheep and 
goats in the Palearctic region. 

In birds also the similarities to our own familiar songsters 
first strike us, though the differences are perhaps really 
greater than in thequadrupeds. We see thrushes and wrens, 
tits and finches, and what seem to be warblers and 
flycatchers and starlings in abundance ; but a closer exam- 


ination shows the ornithologist that what he took for the 
E 


50 ) SEBLAND LIFE PART I 


latter are really quite distinct, and that there is not a single 
true flycatcher of the family Muscicapide, or a single 
starling of the family Sturnide in the whole continent, 
while there are very few true warblers (Sylvude), their 
place being taken by the quite distinct families Mniotiltidee 


or wood-warblers, and Vireonide or greenlets. In like 


manner the flycatchers of America belong to the totally 
distinct family of tyrant-birds, Tyrannidee, and those that 
look like starlings to the hang-nests, Icteridz ; 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 1s 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 lower 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 


Iguanide. Nowhere in the world are the tailed bat- — 


rachians so largely developed as in this region, the Sirens 


and the Amphiumide 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 Palzearctic. 
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 Palearctic, Ethiopian, and Oriental regions. 


: 


Bonar. ITI ZOOLOGICAL REGIONS | 51 
If, however, we compare the number of species, which are 
common to the Nearctic and Palearctic regions with the 
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 shall be obliged to 
admit that the relation that undoubtedly exists between 
the faunas of North America and Europe is of a very 
distinct nature from that which connects together 
Western Europe and North-eastern Asia in the bonds of 
zoological unity. | : 
- Definition and Characteristic Groups of the Neotropical 
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- 
har 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, the armadillos, and the 
ant-eaters ; a series of types more varied, and more distinct 
from those of the rest of the world than any other conti- 
nent can boast of. Among birds we have the charming 
sugar-birds, forming the family Coerebide; the immense 
and wonderfully varied group of tanagers; the exquisite 
little manakins, and the gorgeously-coloured chatterers ; 
the host of tree-creepers of the family Dendrocolaptide ; 
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 groups 
of birds; and no less wonderful is its richness in species, 
simce these fully equal, if they do not surpass, those of the 
| E 2 


— — 
mdorys 


<4 


- 


” 


52 ISLAND LIFE PART 


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 
which are absent. Among mammalia we have first the 
order Insectivora, entirely absent from South America, 
though a few species are found in Central America and 
the West Indies; the Viverridze or civet family is wholly 
wanting, as are every form of sheep, oxen, or antelopes ; 
while theswine, the elephants, and the rhinoceroses of the old 
world are represented bythe 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. LEdentates, 
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 Picarize (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 ofthe 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 parts of the 
world, or the prevalence of a low type of organisation 


among its higher 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, j 


- CHAP. III ZOOLOGICAL REGIONS © 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 cach 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 undoubtedly predominate, and a 
large proportion of the peculiar Neotropical groups extend 
as far as Costa Rica. Even in Guatemala and Mexico we 
have howling and spider-monkeys, coati-mundis, tapirs, 
and armadillos; while chatterers, manakins, ant-thrushes, 
and other peculiarly Neotropical groups of birds are abund- 
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, chatterers, 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 N eotropical, 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. 

Comparison of Zoological Regions with the Geographical 


Divisions of the Globe-—Having now completed our survey — 


of the great zoological regions of the globe, we find that 
they do not differ so much from the old geographical 
divisions as our first example might have led us to suppose. 
-Kurope, 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 Palzearctic 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. Geographical Equivalent. 


Palearctic...... Evrops, with north temperate Africa and Asia. 
- Ethiopian...... - ArFrica (south of the Sahara) with Madagascar. 
Oriental. «220. TROPICAL ASIA, to Philippines and Java. 
‘ Australian .... AUSTRALIA, with Pacific Islands, Moluccas, &c. 
IRCAPELIC 5 5.22: NorTH AMERICA, to North Mexico. 
Neotropical .... SourH AMERICA, with tropical N. America and W. Indies. 


The Euieiae arrangement of the regions will indicate 
their geographical position, and to a considerable extent 
their relation to each other. ot 


NBARCTIC—PALBAARCT IE 


ORIENTAL 
ETHIOPIAN ) {Ta 
N £o- : : cam 
TROPICAL AUSTRALIAN * 


7." & a 


CHAPTER IV 


EVOLUTION THE KEY TO DISTRIBUTION 


Importance of the Doctrine of Evolution—The Origin of New Pca 
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 
Schceniclus—The European and Japanese Jays—Supposed Examples of 
Discontinuity among North American Birds—Distribution and Antiquity 
of Families—Discontinuity a proof of Antiquity—Coneluding 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 
-eauses 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 climatal 
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 PART I 


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 


cHaAp. 1v EVOLUTION THE KEY TO DISTRIBUTION 57 


climates, subsisting on different food, and competing with 
different sets of animals, while the individuals of another 
species will be limited to a small area beyond which they 


seem unable 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 
species 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 prob- 


: 58 ISLAND LIFE PARTI 


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 vary 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. 4 
The Amount of Variation in North 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 
Juscescens (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 per 
cent. on the mean, while the bill varied from °45 to ‘56 
inch in length, and from ‘30 to ‘38 inch in width, or about 
.20 per cent. in both cases. In Dendraca coronata (the 
yellow-crowned warbler) the quills vary in proportionate 
length, so that the Ist, the 2nd, the 3rd, or the 4th, is 
sometimes longest; and a similar variation of the wing 
involving a change of proportion between two or more of 
the feathers is recorded in eleven species of birds. 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, 


 onap. iv EVOLUTION THE KEY TO DISTRIBUTION 59 


while in 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 the breast into a nearly 
continuous patch, In one of the small spotted wood- 
thrushes, Zurdus fuscescens, 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 group 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, 


_1! These facts are ‘taken from a memoir on The Mammals and Winter 


_ Birds of Florida, by J. A. Allen ; forming Vol. II., No. 3, of the Bulletin 


’ or 


of the Museum of Comparative Zoology at Harvard College, Cambridge, 
Massachusetts, ae 7 ; er 


60 ISLAND LIFE PART I 
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 followmg—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 group as the 
type of the species which is best adapted to the conditions 
in which it has actually to exist. This type will therefore 
always form the majority, because the struggle for 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 may 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, 


1 The great variation in wild animals is more fully discussed and 
illustrated in the author’s Darwinism (Chapter III.). 


* 
; 


Har. iv EVOLUTION THE KEY TO DISTRIBUTION 61 
each formed by a combination of certain 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 
original 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 which 
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; while 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 with other animals, 
will spread over a wider area, and increase so as to become 
common species. Sometimes these will acquire such a 
perfection of organisation by successive favourable modi- 
fications that they will be able to spread greatly beyond 
the range of the parent form. They then become what 
are termed dominant species, maintaining themselves in 
vigour and abundance over very wide areas, displacing 
other species with which they come into competition, and, 
under still further changes of conditions, becoming the 
parents of a new set of diverging species. 

Definition and Origin of Genera.—As some of the most 
important and interesting phenomena of distribution relate 


\ 


69 . ISLAND LIFE | PART 1 


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 will 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 will 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 


cHar. 1v 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 Extinction of Species—There 1s 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 
i 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 portionsof - 
_ 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 affords means of 
concealment and protection, and we sometimes find in such 
localities a few remnants of low types in the midst of a 
_ general assemblage of higher forms. Some of the most 
_ ancient types now living inhabit caves like the Proteus, or 
_ bury themselves in mud like the Lepidosiren, or in sand 
like the Amphioxus, the last being the most primitive of 
all vertebrates ; while the Galeopithecus and Tarsius of the 
Malay islands and the potto of West Africa, survive amid 
_ the higher mammalia of the Asiatic and African continents 


PRA en) ie ies 


ani 


64 ISLAND LIFE PART f 
owing to their nocturnal habits and concealment in the 
densest forests. 

The fise and Decay of Species and Genera.—The 
preceding sketch of the mode in which species and genera 
have arisen, have come to maturity, and then decay, leads 
us to some very important conclusions as to the mode of 
distribution of animals. When a species or a genus is 
increasing and spreading, it 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 whole 
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 Specific Areas, why Rare-—But although 
discontinuous generic areas, or the separation from each 
other of species whose 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 


, a: Wedel ale 
a ei Mk 2) ie, a Oe 


_ cnap. tv EVOLUTION THE KEY TO DISTRIBUTION 65 


- 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 Parus palustris,—Mr. See- 
bohm, who has travelled and collected in Europe, Siberia, 
and India, and possesses extensive and accurate knowledge 
of Palzarctic birds, has recently called attention to the 
varieties and sub-species of the marsh tit (Parus palustris), 
of which he has examined numerous specimens ranging 
from England to Japan.!. The curious point is that those 
of Southern Europe and of China are exactly alike, while 
all over Siberia a very distinct form occurs, forming the 
_ sub-species P. borealis? - In Japan and Kamschatka other 


See Ibis, 1879, p. 32. 

2 In Mr. Seebohm’s latest work, Birds of the Japanese Empire (1890), 
he says, ‘‘ Examples from North China are indistinguishable from those — 
obtained in Greece” (p. 82). 


F 


66 ISLAND LIFE PART I 


varieties are found, which have been named respectively 
P. japonicus and P. camschatkensis and another P. songarus 
in Turkestan and Mongolia. 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 Paruws borealis is a distinct species from 
Parus palustris, as it 1s reckoned in Gray’s Hand List of 
Birds, and also in Sharpe and Dresser’s Birds of Hurope, 
then Parus palustris 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 m 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 LP. palustris and P. borealis 
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 Emberiza schaeniclus—The other case 
is that of our reed bunting (Hmberiza scheniclus); 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, H. passerina, 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 (&, pyrrhulina), 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 Ibis, 1879, p. 40. In his Birds of the Japanese Empire (1890), Mr. — 
Seebohm classes the Japanese and European forms as ZH. scheniclus, 
and thinks that their range is probably continuous across the two 
continents. 


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onar. tv EVOLUTION THE KEY TO DISTRIBUTION 67 
The European and Japanese Jays—Another case some- 
what resembling that of the marsh tit is afforded by the 
European and Japanese jays (Garrulus glandarius and G. 
japonicus). Our common jay inhabits the whole of Europe 
except the extreme north, but isnot known to extend any- 
where 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. yaponicus) 
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 fromit. Looking at the map exhibiting the 
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 gradually 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 Hxamples of Discontinuity 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 
Rocky 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 west, while the mcuntain 
range is broken up by passes and valleys. It thus happens 
that most species of birds which inhabit both the eastern 
and western coasts of the North American continent 
have maintained their continuity towards the north, 
while even when differentiated into two or more allied 


a: 


68 ISLAND LIFE PART I 


species their areas are often contermimous or _ over- 
lapping. 

Almost the only bird that seems to have a really discon- 
tinuous range is the species of wren, Thryothorus bewickii, 
of which the type form ranges from the east coast to 
Kansas and Minnesota, while a longer-billed variety, 
T. tewicku spilurus, is found in the wooded parts of 
California and as far north as Puget Sound. If this 
really represents the range of the species there remains a 
gap of about 1,000 miles between its two disconnected areas. 
Other cases are those of Vireo bellu of the middle United 
States and the sub-species puszllus of California; and of 
the purple red-finch, Carpodacus purpureus, with its variety 
C’. californicus ; 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 pomt 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. 

Mnstribution and Antiquity of Families—Just as genera 
are groups of allied species distinguished from all other 
groups by some well-marked structural characters, so 
families are groups of allied genera distinguished by more 
marked and more important characters, which 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 the species 
of which it is composed, because during its growth and de- 
velopment the original rudimentary species becomes sup- 


a ttt tin pee ee 


a” ide Le 


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3 
8 

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i 
: 
oe 
eI 
. 
5 
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vi 


CHAP. Iv EVOLUTION THE KEY TO DISTRIBUTION 69 


planted by more and more perfectly adapted forms, so a 
family is usually older than its component genera, and 
during the long period of its life-history may have survived 
many and great 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. 

scontinurty a Proof of Antiguity.—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 Lepidosiren paradoxa is 
only known from the Amazon and some other South 
American rivers. An allied species, Lepidosiren annectens, 
sometimes placed in a distinct genus, inhabits the Gambia 
in West 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 lving 
Ceratodus that both are referred to the same genus. 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, while in North 
America the Devonian rocks have yielded a gigantic allied 
form which has been named Heliodus by Professor Newberry. 
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 other, we may be sure that they are the 
remnants of a once extensive group of genera; and if we 


70 ISLAND LIFE PART I 


ee 


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 countries 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 even 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 which are now represented by disconnected genera 
are known to have occupied intervening lands or to have 
had an almost continuous distribution m 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 
was or must have been effected by means of contents now 
sunk beneath the ocean. 

Concluding Remarks.—When writing 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 such numerous forms of one type could only 
have been developed in a wide area and under varied 
conditions, implying a great lapse of time. In our 
succeeding chapters we shall show that the known and 
probable changes of sea and land, the known changes of 
climate, and the actual powers of dispersal of the different 
groups of animals, were such as would have enabled all the 
now disconnected groups to have once formed parts of a 
continuous series. Proofs of such former continuity are 
continually being obtained by the discovery of allied extinct 
forms in intervening lands, but the extreme imperfection 
of the geological record as regards land animals renders it 


Oe Wl ‘Hii ioe. Rath Hick eee sug 7 oe ee: 


adie ais pce Jak eaaaial a 
Gubiees viet nee eee 
si N THE KEY TO DISTRIBUTION © val 


y tl Be this ea will be forthcoming i in the maj jority 
The notion that if such animals ever existed 
ains would certainly be found, is a superstition 


vely prevails among naturalists ; but until it is got 
true notions of the former distribution of life upon 
rth can be attained. 


gh, a ; ui ’ ge 


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 Abundance of 
Land-shells—The Dispersal of Plants—Special adaptability of Seeds for 
Dispersal—Birds as agents in the Dispersal of Seeds—Ocean Currents as 
agents in Plant Dispersal—Dispersal along Mountain-chains—Antiquity 
of Plants as affecting their Distribution. 


In order to understand the many curious anomalies we 
meet with in studying the distribution of animals and 
plants, and to be able to explain how it 1s that some 
species and genera have been able to spread widely 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 geological 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 wide 
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 the 


OMAP. v DISPERSAL OF ANIMALS AND PLANTS 73 


particular cases that arise in regard to the faunas and floras 
of remote islands. But the other side of the question of 
dispersal—that which depends on geological and climatal 
changes-—is in a far less satisfactory condition, for, though 
much has been written upon it, the most contradictory 
opinions still prevail, and at almost every step we find 
ourselves on the battle-field of opposing schools in 
geological or physical science. 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 venture to hope may serve as the foundation for a better 
comprehension of these intricate problems. The four 
chapters which follow this are devoted to a full examin- 
ation of these profoundly interesting and important 
questions, after which we shall enter upon our special 
Inquiry—the nature and origin of insular faunas and 
floras, | 
_ The Ocean asa Barrier to the Dispersal of Mammals.—A 
wide extent of ocean forms an almost absolute barrier to 
the dispersal of all land animals, and of most of those 
which-are aerial, since even birds cannot fly for thousands 
of miles without rest and without food, unless they are 
aquatic birds which can find both rest and food on the 
surface of the ocean. We may be sure, therefore, that 
without artificial help neither mammalia nor land birds can 
pass over very wide oceans. The exact width they can 
pass over is not determined, but we have a few facts to 
guide us. Contrary to the common notion, pigs can swim 
very well, and have been known to swim over five or six 
miles of sea, and the wide distribution of pigs in the islands 
of the Kastern Hemisphere may be due to this power. It 
is almost certain, however, that they would never 
voluntarily swim away from their native land, and if 
carried out to sea by a flood they would certainly endeay- 
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 mammalia. 


74 ISLAND LIFE | PART I 


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 
growlng on a stratum of soil which even formed a white 
beach round the margin of each raft. Among the 
Philippine Islands similar rafts with trees growing on them 
have 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-pomt. 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 would no doubt be rare. Insects, however, and 
Jand-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 such 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, we may 
be sure that an actual land connection, or at all events an 
approach to within a very few miles of each other, has at one 
time existed. 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, which is 
so shallow that a rise of less than a thousand feet would 


a 


“5 ex. Vv DISPERSAL OF ANIMALS AND PLANTS 75 


form a broad isthmus connecting Asia and America as far 


south as the parallel of 60° N. Continuity of land there- 
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 we maintain to be the only explanation of 
most anomalies of distribution other than such as may be 
connected with unsuitability of chmate. 

The Dispersal of Birds—Wherever mammals can mi- 
grate 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 Dispersal of Leptiles—Reptiles appear at first 
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 reproduction. A large boa-constrictor 
was once floated to the island of St. Vincent, twisted 
round the trunk of a cedar tree, and was so little injured 
by its voyage that it captured some sheep before it was 
killed. The island is nearly two hundred miles from 
Trinidad and the coast of South America, whence the 
reptile almost certainly came.1 Snakes are, however, 
comparatively scarce on islands far from continents, but 
lizards are often abundant, and though these might also 


travel on floating trees, it seems more probable that there 


1 Lyell’s Principles of Geology, ii., p. 369, 


76 ISLAND LIFE PART I 


is some as yet unknown mode by which their eggs are 
safely, though perhaps very rarely, conveyed from island 
to island. Examples of their peculiar distribution will be 
given when we treat of the fauna of some islands in which 
they abound. 

The Dispersal of Amphibia and Fresh-water Fishes.— 
The two lower groups of vertebrates, Amphibia and fresh- 
water fishes, possess special facilities for dispersal, in the 
fact of their eggs being deposited in water, and in their 
aquatic or semi-aquatic habits. They have another 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 the globe. 
Some genera of Batrachia have almost a world-wide dis- 
tribution ; while 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 portions, where 
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 ponds and rivers, 
and thus disperse eggs and even small fishes. As a rule, 
however, the same species are not often found in countries 
separated by a considerable extent of sea, and in the 
tropics rarely the same genera. The exceptions 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. 
Where exceptions occur, it is often due to the great 


—- se ee 


ee ea) ee 


cnar.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 more 
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 tropical rivers 
of both hemispheres have arisen from allied marine forms 
_ becoming gradually modified for a life in fresh water. 
_ By some of these various causes, or a combination of them, 

most of the facts in the distribution of fishes can be 

explained without much difficulty. 

The Dispersal of Insects—In the enormous group of 
insects the means of dispersal among land animals reach 
their maximum. Many of them have great powers 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 
larvee often inhabit solid timber, or lurk under bark or 
im crevices of logs, and may thus reach any countries to 
which such logs are floated. Another important factor im 
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 1s all the 
more surprising that with such powers of migration they 
should yet be often as restricted in their range as the 
reptiles or even the mammalia. The cause of this 
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 


78 ISLAND LIFE PART 1 


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 itis 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 Mr. Darwin found that the large Helix pomatia 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 
floated 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 


DISPERSAL OF ANIMALS AND PLANTS 


their powers of voluntary dispersal, even on land, are very 
limited, and this will explain the extreme restriction of their 
range in many cases. __ 
Great Antiquity of Land-Shells.—The clue to the almost 
“universal distribution of the several families and of many 
Peenera, 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 
a living genera, aa 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 
3 certainly have abounded, for in the far more ancient 
Palzeozoic 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 Paleozoic 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 variety 
_ Of species and genera bears a direct relation to the facilities 
_ of transfer, and the shell fauna is never very rich and 
varied. except in countries which have at one time or other 
- been united to some continental land. 
Causes Favouring the Abundance of Land-Shells—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 much rugged 


water in calm weather, the distance might 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 pr obably 
the most efficient cause of their very wide diffusion. 


80 ISLAND LIFE 7 PART I 


rock offermg 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 group of 
animals whatever, but which is perhaps explained by the 
considerations now suggested. 

The Dispersal of Plants—The ways in which plants are 
dispersed over the earth, and the special facilities they often 
possess for migration have been pointed out by eminent 
botanists, and a considerable space might be occupied in 
giving a summary of what has been written on the subject. 
In the present work, however, it 1s 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. 

Special Adaptability of Seeds for Dispersal—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 fora 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 


¥ — -<;. 


CHAP. V DISPERSAL OF ANIMALS AND PLANTS 81 
year a million seeds were brought by the 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 adapted to be carried by the wind, and that 
winds of great violence and long duration occur in most 
parts of the world, we are as sure that seeds must be 
carried to great distances as if we had seen them so carried. 
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 in 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 Chapter XII. 
when discussing the origin of the flora of the Azores and 
Bermuda. 

Ocean-currents as Agents in Plant-dispersal.—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. 

Dispersal along Mountain Chains.—These various modes 
of transport are, as will be shown when discussing special 
‘cases, amply sufficient to account for the vegetation found 
on oceanic islands, which almost always bears a close 

G 


82 ISLAND LIFE papel 


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 probably 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 débris on mountain 
sides and summits, offermg stations on which se 
plants can temporarily establish themselves. 

Antiquity of Plants as affecting theo Distribution —We 
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 possess, 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 Nature and Extent—Shore-deposits and 
Stratified Rocks—The Movements of Continents—Supposed Oceanic 
Formations ; the Origin of Chalk—Fresh-water and Shore-deposits as 
proving the Permanence of Continents—Oceanic Islands as indications 
of the Permanence of Continents and Oceans—General Stability of 
Continents with constant Change of Form—Effect of Continental 
Changes on the Distribution of Animals—Changed Distribution proved 

_ by the Extinct Animals of Different Epochs—Summary of Evidence 
for the general Permanence of Continents and Oceans. 


THE changes 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 we 
can hardly exclude the surfaces occupied by volcanic and 
fresh-water deposits, since, In many cases, if not in all, 
these rest upon a substratum of marine formations. At 
first sight, therefore, it seems a necessary inference that 
when the present continents were under water there must 

G 2 


84 ISLAND LIFE PARTI 


have been other continents situated where we now find the 
oceans, from which the sediments came to form the various 
deposits we now see. ‘This view was held by so acute and 
learned a geologist as Sir Charles Lyell, who says :— 
“Contents, therefore, although permanent for whole 
geological epochs, shift their positions entirely in the course 
of ages.”! Mr. T. Mellard Reade, late President of the 
Geological Society of Liverpool, so recently as 1878, says :— 
“While believing that the ocean-depths are of enormous 
age, it is impossible to resist other evidences that they 
have once been land. The very continuity of animal and 
vegetable life on the globe points to it. The molluscous 
fauna of the eastern coast of North America is very 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 with respect to the sea were confined within 
limits near the present continents, the results would have 
been a gradual dimimution instead of development 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, while the land would be composed of sand- 
stones and argillaceous shales. The evidence of chemistry 
thus confirms the inductions drawn from the distribution 
of animal life upon the globe.” 


1 Principles of Geology, 11th Ed., Vol, I., p. 258. 
2 On Limestone as an Index of Geological Time. 


cHAP. VI GEOGRAPHICAL AND GEOLOGICAL CHANGES 85 


So far from this being a “mathematical demonstration,” 
it appears to me to be a complete misinterpretation of 
the facts. Animals did not create the lime which they 
secrete from the sea-water, and therefore we have every 
reason to believe that the imorganic sources which 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 depth, that is, near 
land, while there is no proof whatever that there is any 
considerable accumulation of limestone at the bottom of 
the deep ocean. On the contrary, the fact ascertained by 
the Challenger, that beyond a _ certain depth the 
“calcareous” ooze ceases, and is replaced by 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 compared with 
older formations, it may be readily explained by two 
considerations : in the first. place, the growth and develop- 
ment of the land in longer and more complex shore lines 
and the mcrease 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 may 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. 

Shore Deposits and Stratified Rocks ——Ilf we go round the . 
shores of any of our continents we shall almost always find a 
considerable belt of shallow water, meaning thereby water 
from 100 to 150 fathoms deep. The distance from 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, while in some cases such shallow seas extend 
several hundred miles from existing continents. The great 
depth of a thousand fathoms is often reached at thirty 
miles from shore, but more frequently at about sixty or a 
hundred miles. Round 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 always 
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 smking comparatively near shore, 
while only the very finest and almost impalpable mud will 
be carried out to the furthest hmits. 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 within 50 or 100 
miles of then existing continents, or if ata greater distance, 
in shallow inland seas receiving deposits from more sides 
than one, or in certain exceptional areas where deep ocean 
currents carry the débris of land to greater distances.’ 

1 In his Preliminary Report on Oceanic Deposit, 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.” (Proceedings of the Royal Society, 
Vol. XXIV. 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.) 


oHAP. 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 shales, which 
must, as we have seen, have been deposited within 
a comparatively short distance of a sea-shore. Sir 
Archibald Geikie says :—“ Among the thickest masses of 
sedimentary rock—those of the ancient Palzeozoic 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 poit to shallow 
and even littoral waters. They occur from bottom to top 
of formations, which reach a thickness of several thousand 
feet. They can be 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 
oradually subsided for thousands of feet ; yet that the rate 
of accumulation of sediment kept pace on the whole with 
this depression ; and hence that the original shallow-water 
character of the deposits remained, even after the original 
sea-bottom had been buried under a vast mass of sedi- 
mentary matter.” He goes on to say, that this general 
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. We 
find them stretching across the country in one general 
direction, in belts of no great width though often of immense 
length, just as we should expect in shore deposits; and 
they often thin out and change from coarse to fine in a 
definite manner, indicating the position of the adjacent land 


1 Geographical Evolution, (Procecdings of the Royal Geographical sea 
1879, p. 426.) 


88 ISLAND LIFE PART I 


from the débris 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 mud 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, while 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 which 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 subaérial denudation into peaks and 
valleys, constitute our great mountain systems.! In this 


1 Professor Dana was, I believe, the 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 


“f a . a oe 


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= ~ ." 99 


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ri 
i 


CHAP. VI GEOGRAPHICAL AND GEOLOGICAL CHANGES 89 


way every part of a continent may again and again have 
sunk beneath the sea, and yet as a whole 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 of 
marine strata many thousand feet thick may have been 
formed in a sea which was never very 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 Chalk.— 
There seems very good reason to believe that few, if any, of 
the rocks known to geologists correspond exactly to the de- 
posits now forming at the bottom of our great oceans. The 
white oceanic mud, or Globigerina-ooze, found in all the great 
oceans at depths varying from 250 to nearly 3,000 fathoms, 
and almost constantly in depths 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 chiefly 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 porifera vitrea,. which find their 
nearest representatives among the Ventriculites of the 
white chalk. The echinoderm fauna of the deeper parts of 


restricted adjacent areas ; and the effect has been to bring each portion in 
succession beneath the ocean but always bordered on one or both sides by 
the remainder of the continent, from the denudation of which the deposits 
are formed which, on the subsequent upheaval, become mountain ranges. 
(Manual of Geology, 2nd Ed., p. 751.) 


90 ISLAND LIFE PARTI 


the Atlantic basin is very characteristic, and yields an 
assemblage of forms which represent in a remarkable 
degree the corresponding group in the white chalk. 
Species of the genus Cidaris are numerous ; some remark- 
able flexible forms of the Diademidz 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, with from 5 to 11 per cent of silica, and from 8 to 
33 per cent. of alumina and oxide of iron.? Chalk, on the 
other hand, contains usually from 94 to 99 per cent. of 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 1s 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 Nature, Vol. II., p. 297. 


2 Sir W. Thomson, Voyage of Challenger, Vol. II., p. 374. 
3 The following is the analysis of the chalk at Oahu :— 


Carbonate of Tame, a2. 65 sncircccgoGeeees 92°800 per cent. 
Carbonate of Magnesia fic... ccie 2. 2°385 a 
MGM casi cee ogre eee eee 0°250 ‘i 
OSTAS GL RTO | od. ourag he eae eee z 
Ld eae MM ay De MAE SS” MeN Sigs ie 0°750 is 
Phosphoric Acid and Fluorine ......... 2°113 5 


Water and loss ..... ..... 


— 
v >. 
Pe 


Pd 


CHAP. vi GEOGRAPHICAL AND GEOLOGICAL CHANGES 91 


that the pure calcareous mud produced by the decompo- 
sition of the shelly coverings of mollusca and zoophytes 
would be much lighter than argillaceous or arenaceous mud, 
and being thus transported to greater distances would be 
completely separated from all impurities. 

Now the Globigerinz have been shown by the Challenger 
explorations to abound in all moderately warm seas ; living 


This chalk consists simply of comminuted corals and shells of the 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 Exploring Expedition, p. 150.) Mr. Guppy also found 
chalk-like coral limestones containing 95 p.c. of carbonate of lime in the 
Solomon Islands. 

The absence of Globigerinw is a local phenomenon. They are quite 
absent in the Arafura Sea, and no G'lobigerina-ooze was found in any of 
the enclosed seas of the Pacific, but with these exceptions the Globigerine 
‘fare really found all over the bottom of the ocean.” (Murray on Oceanic 
Deposits—Proceedings of Royal Society, Vol. XXIV., p. 523.) 

The above analysis shows a far closer resemblance to chalk than that 
of the Globigerina-ooze of the Atlantic, four specimens of which given by 
Sir W. Thomson (Voyage of the Challenger Vol. II. Appendix, pp. 374- 
376, Nos. 9, 10, 11 and 12) from the mid-Atlantic, show the following 
proportions :— 


Carbonate of Lime ............ 43°93 to 79°17 per cent. 
Carbonate of Magnesia ...... 1°40. - to 2°58 : 
Alumina and Oxide ofIron. 6°00?% to 32°98 ei 
ES 4°60 to 11°23 cK 


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 either in the 
air or by 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. Forbes will show the difference 


between the two formations :— 
Grey Chalk, White Chalk, 


Folkestone. Shoreham. 
Sarponate of Lime.................. 94°09 98°40 
Carbonate of Magnesia ...... ..... 0°31 0°08 
Alumina and Phosphoric Acid... a trace 0°42 
Saeride Of Sodium ................ 1°29 — 
Bele GEDTIS ............-....+--. 3°61 1°10 


(From Quarterly Journal of the Geological Socicty, Vol. XXVII.) 

The large proportion of carbonate of lime, and the very small quantity 
of silica, alumina, and insoluble déb77s, at once distinguish true chalk from 
the Globigerina-ooze of the deep ocean bed. 


92 ISLAND LIFE PART I 


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 dredgings and surface-gatherings of the 
Challenger by Mr. H. B. Brady has led him to a different 
conclusion ; for he finds numerous forms at the bottom 
quite distinct from those which inhabit the surface, while, 


when the same species live both at surface and bottom, the 


latter 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 Globigerinz 
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 


1 Notes on Reticularian Rhizopoda ; in Microscopical Journal, Vol. XIX., 
New Series, p. 84. 
a Proceedings of the Royal Society, Vol. XXIV. p. 532. 


“> 


Pe ee ee ee 


¥ ek oe ie aoe 35. 


CHAP. VI GEOGRAPHICAL AND GEOLOGICAL CHANGES 93 
authorities on shells, who has himself dredged largely both 
in deep and shallow water and who has no theory to support, 
has carefully examined this 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 the dee 
Atlantic ooze—Leda, Verticordia, Nezra, 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 within 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 
North-western Russia, where Paleozoic and ancient 
Secondary rocks have a wide extension, though now 
partially concealed by late Tertiary deposits ; while on 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 Primeval World of 
Switzerland, p.175. To the north the sea may have had 


1 See Presidential Address in Sect. D. of British Association at Plymouth, 
877. ae 


94 ISLAND LIFE PARTI 


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 pure 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 composed 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 
portion of the Gulf Stream would be diverted into the 
inland European sea, and would bring with it that abun- 
dance of Globigerinz, 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 


cuar. v1 GEOGRAPHICAL AND GEOLOGICAL CHANGES 98 


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 no 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. 8. P. Woodward thinks that 
these organisms were limited to a depth 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 continued along the Atlantic coast of 
America. The commonest genera met with in this 
deposit are Globigerina, Rotalia cultrata in large numbers, 
several Textilarize, Marginuline, &c. Beside these, small 
free corals, Aleyonide, Ophiure, 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 which seems to have 
been altogether overlooked by those who suppose that a 
deep and open island-studded ocean occupied the place of 
Kurope 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- 
| 1 Geological Magazine, 1871, p. 426. 


96 ISLAND LIFE PARTI 


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. Now, what does this gap mean? 
It implies that when the deposition of the various Creta- 
ceous beds of Kurope 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 1s now European land was below the sea- 
level. It was only when this period terminated that large 
areas in several parts of HKurope became submerged and 
received the earliest Tertiary deposits known as Eocene. 
If, therefore, Europe at the close of the Cretaceous period 
was generally identical with what it is now, and perhaps 
even more extensive, it is absurd to suppose that it was all, 
or nearly all, under water during that period; or in fact, 
that any part of it was submerged, except those areas on 
which we actually find Cretaceous deposits, or where we 
have good reason to believe they have existed ; 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 
ereat 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 present day.1 


1 Tn his lecture on Geographical Evolution (which was published after the 
greater part of this chapter had been written) Sir Archibald Geikie expresses 
views in complete accordance with 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 more than a few hundred feet deep over 


KC 


fae 
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ay 
\ . fast 


CHAP. VI GEOGRAPHICAL AND GEOLOGICAL CHANGES 97 


Fresh-water and Shore Deposits as Proving the Permanence 
of Continents,—The view here 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 have 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 Rocky 
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 
eulfs 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 gathered a vast mass of calcareous mud, composed 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, who would have treated any arguments advanced by myself 
as not worthy of consideration. 
H 


98 ISLAND LIFE PART I 
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 England, 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, msects and mammals; the Bavarian litho- 
eraphic 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 describes it as having been between fifty and sixty 
feet long, and when standing erect at least thirty feet . 
high !1 Such monsters could hardly have been developed 
except in an extensive land area. A small mammal, 
‘Dryolestes, 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, amphibians 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 im 
Germany ; while the beds of rock-salt in this formation, 


1 Introduction and Succession of Vertebrate Life in America, by Professor : 
O. C. Marsh. Reprinted from the Popular Science Monthly, March, April, 
1878. 


cHAP. Vi GEOGRAPHICAL AND GEOLOGICAL CHANGES 99 


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 Palzeozoic 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 Russia. Coalfields of the same age occur in 
Ohio in North America. Inthe 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, Spitzbergen, 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 rich 
vegetation and extensive land areas, carries back the proof 
of the persistence and general identity of cur 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, which 
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- 
eracks 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 deeply covered up 
by later marine or volcanic formations, we cannot but be 
struck by the abounding proofs of the permanence of the 

* Physical Geography and Geology of Great Britain, 5th Ed. p. . 

H 


100 ISLAND LIFE Pant 7 


great features of land and sea as they now exist; and we 
shall see how utterly gratuitous, and how entirely opposed 
to all the evidence at our command, are the hypothetical 


continents bridging over the deep oceans, by the help — 


of which it is so often attempted to cut the Gordian 
knot presented by some anomalous fact in geographical 
distribution. 

Oceanic Islands as Indications of the Permanence of 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 Species, 6th Ed. p. 288): “ Looking to 
existing oceans, which are thrice as extensive as the land, 
we see them studded with many islands; but hardly one 
truly oceanic island (with the exception of New Zealand, 
if this can be called a truly oceanic island) is as yet known 
to afford even a fragment of any Paleozoic or Secondary 
formation. Hence we may perhaps infer that during the 
Palzeozoic and Secondary periods neither continents nor 
continental islands existed where our oceans now extend ; 
for had they existed, Palzeozoic 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 we may infer anything from these 
facts, we may infer that, where our oceans now extend, 
oceans have extended from the remotest period of which 
we have any record; and, on the other hand, that where 
continents now exist, large tracts of land have existed, 
subjected no doubt to great oscillations of level, since the 


Cambrian period.’ This argument standing by itself has — 


not received the attention it deserves, but coming in sup- 
port of the long series of facts of an altogether distinct 


nature, going to show the permanence of continents, the — 
cumulative effect of the whole must, I think, be admitted 


to be irresistible.t 


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 adopted this view, speaking of the great belt of — 


cnap. vi GEOGRAPHICAL AND GEOLOGICAL CHANGES 101 


General Stability of Continents with Constant Change of 
Form.—lt 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 by the recent 
soundings of H.M.S. Challenger a mountain-range, comparable in its 
extent, elevation, and volcanic character with the Andes of South America” 
(Geological Mag. 1874, p. 71). On examining the diagram of the Atlantic 
Ocean in the Challenger Reports, No. 7, a considerable part of this ridge is 
found to 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 are considerable areas varying from 1,200 
to 1,500 fathoms.deep, while 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 explain the presence of a few identical genera, 
and even species of plants and insects in Africa and South 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 considerably to the weight of the 
evidence here submitted for the permanence of oceanic and continental 
areas. 


102 ISLAND LIFE PART TE @ 


upraised coral reefs of inland seas. The mountains of one 
period have disappeared by denudation or subsidence, 
while the mountains of the succeeding period have been 
rising from beneath the waves. ‘The valleys, the ravines, 
and the mountain peaks, have been carved out and filled 
up again; and all the vegetable forms which clothe the 
earth and furnish food for the various classes of animals 
have been completely changed again and again. 

Lifect 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 wide-spread groups 
whose distribution often puzzlesus. Owing to the repeated 
isolation of portions of continents for long periods, special 
forms of life would have time to be developed, which, when 
again brought into competition with the fauna from which 
they had been separated, would cause fresh struggles of 
ever 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 proved by the Extinct Animals of 
Different Epochs—We thus find that, while the inorganic 
world has been in a state of continual though very gradual 
change, the species of the organic world have also been 
slowly changing in 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 


Pe 
ct 


‘a cHAP. vit GEOGRAPHICAL AND GEOLOGICAL CHANGES 103 


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 world as we 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 
hght upon the past history of our globe and its inhabitants, 
and can sketch out with confidence many of the changes 
they must have undergone. : 
Summary of Hvidence for the General Permanence of 
Concrnents and Oceans.—As this question of the permanenc 
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.1 We know as a fact 


1 In a review of Mr. T. Mellard 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 favour 
from Mr. Reade, whose geological knowledge is practical as well as theoretical. 
“hey 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. Mr. Reade points out that the first proposition is not 
yet proved, and the distribution of animals and plants and the fact that 
the bulk of the strata on land are of marine origin are opposed. to the hypo- 


104 ISLAND LIFE PART I 


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 
ereat 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 
ereat 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 proof that any 
part of the series of known geological formations exactly 
resembles them. Chalk, which isstill 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 whether 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.” 


Ye 


cHAP. vi GEOGRAPHICAL AND GEOLOGICAL CHANGES 105 


forms throughout the whole of that enormous lapse of 
time. 

On the side of the oceans we have also a great weight 
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 the 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 Paleozoic or Secondary rocks— 
that is, have not preserved any fragments of the supposed 
ancient continents, nor of the deposits which must have 
resulted from their denudation during the whole 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. 

Since the last edition of this book appeared, I have 
added two other general arguments to those here adduced 
indicating the extreme improbability, if not the impossi- 
bility, of the great oceanic areas ever having been con- 
tinents. The one depends on the contours of the ocean 
floors, now fairly well known, and presenting a radical 
difference from that which they would present had they 
been submerged continental land. ‘The other is founded 
on the almost identical range and completeness of the 
geological series of formations in all the great continents. 
These arguments are set forth in my Studvzes Scientific and 
Social, vol. 1., chap. 2, and, in combination with those here 
adduced, will, I think, carry conviction to most students 
of the subject. 


CHAPTER VIT 


CHANGES OF CLIMATE WHICH HAVE INFLUENCED THE 
DISPERSAL OF ORGANISMS : THE GLACIAL EPOCH 


Proofs of the Recent Occurrence of a Glacial Epoch—Moraines—Travelled 
Blocks—Glacial Deposits of Scotland : the ‘‘ Till ”»—Inferenees from the 
Glacial Phenomena of Scotland—Glacial Phenomena of North America 
—Effects of the Glacial Epoch on Animal Life—Warm and Cold Periods 
—Paleontological Evidence of Alternate Cold and Warm 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 revolu- 
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 


des, v1 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 Occurrence of a Glacial Hpoch.—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 glacia- 
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 strize 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 striz 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, are found 
ground off to a perfectly smooth but never to a flat surface. 
These rounded surfaces are found not only on single rocks 
but over whole valleys and mountain sides, and form what 


a 


108 ISLAND LIFE PART I q 


are termed roches moutonnées, from their often having the — 
appearance at a distance of sheep lying down. 

Now these two phenomena are actually produced by 
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 débris forms 
long lines on each side, or on the centre whenever two 
elacier-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 1s 
most remarkable, having no apparent natural relation to 
the 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, — 


Betar. vil THE GLACIAL EPOCH | 109 


_ Exactly similar mounds are found in the valleys of North 
Wales and Scotland, and always where the other evidences 
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 PART 1 


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 im 
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 which the blocks are convposed, 
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 Alpime 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 Blane 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 (/ e d), while those found — 
towards Geneva have all come from the west side (ph). 
It is also very suggestive that the highest blocks on the — 


THE GLACIAL EPOCH 111 


Jura at G have come from the eastern shoulder of Mont 
lane in the direct line BF G. Here the glacier would 
aturally preserve its greatest thickness, while as it spread 
it eastward and westward it would become thinner. We 
cordingly find that the travelled blocks on either side of 


-- 
== 


MAP SHOWING THE COURSE OF THE ANCIENT GLACIER OF THE RHONE AND THE 
DISTRIBUTION OF ERRATIC BLOCKS ON THE JURA. 


a 
| 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 


112 ISLAND LIFE PART tm 


view he had first adopted—that the blocks had been — 


carried by floating ice during a period of submiggeeteaam 


altogether untenable. 


The phenomena now described demonstrate a change of — 


climate sufficient 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 1s most important for our purpose to 


understand the amount of the climatal changes the northern — 


hemisphere has undergone, I will endeavour to make the 
evidence intelligible, referring my readers for full details 
to Dr. James Geikie’s descriptions and illustrations.” 
Glacial Deposits 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 clayey 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 striz 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, 4th Ed. pp. 340-348. . 
2 The Great Ice Age and its Relation to the Antiquity of Man. By James 
Geikie, F.R.S. (Isbister and Co., 1874.) 


ne 
- 
s 
bi 
: 
‘ 
« 


OMAP. VIT THE GLACIAL EPOCH | 113 


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 high 
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 character of 
the rock of the district where it occurs, so that it is clearly 
—alocal 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 
strize, perched blocks, roches moutonnées, 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 length 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 maxt- 
mum thickness, and continually moving seaward with a 
slow grinding motion like that of all existing glaciers, 


* I 
4 
= 

as 


114 ISLAND LIFE PART I 


must have ground down the whole surface of the country, 
especially all the prominences, leaving the rounded rocks 
as well as the grooves and strizw 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 ~roches 
moutonnees. 

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 water 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 itis 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 Mr. Searles V. Wood, 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 — 


a 
» ro 7 


CHAP. VII THE GLACIAL EPOCH 115 


There is good evidence that, when the ice was at its maxi- 
mym, 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 the pressure will 
depend on its thickness. Now the points of maximum thickness must 
have often changed their positions, and the result would be that the 
matter ground out in one place would be forced into another place where 
the pressure was less. If there were no lateral escape for the mud, it 
would necessarily support the ice over it just as a water-bed supports the 
person lying on it ¢ and when there was little drainage water, and the ice 
extended, say, twenty miles, in every direction from a given part of a valley 
where the ice was of less than the average thickness, the mud would 
necessarily accumulate at this part simply because there was no escape for 
it. Whenever the pressure all round any area was greater than the pressure 
on that area, the débris 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 débris. 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 débris 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 for 
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 Man, where ‘‘till” similar to that 
in Scotland abounds, and rocks are found in it which must have come from 
Cumberland and Scotland, as well as from the north of Ireland. This 
would show that glaciers from each of these districts reached the Isle of 
Man, 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. (See 4 Sketch of the Geology of the Isle of Man, by John Horne, 
F.G.S. Trans. of the Edin. Geol. Soc. Vol. II. pt. 3, 1874.) 

I 2 


116 ISLAND LIFE PART I 


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 im 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 simple way, 
It is to prevent my readers being imposed upon by any such 
statements or doubts, that I have given this very brief and 


imperfect outlne of the nature, extent, and completeness 


CHAP, VII THE GLACIAL EPOCH 117 
of the evidence on which the existence of the glacial epoch 
depends. There is perhaps no great conclusion in any 
science which rests upon a surer foundation than this ; and 
if we are to be guided by our reason at all in deducing the 
unknown from the known, the past from the present, we 
cannot refuse our assent to the reality of the glacial 
epoch of the northern hemisphere in all its more important 
features. 

Hiffects of the Glacial Epoch on Animal Life: Warm and 
Cold Periods.—It is hardly necessary to point out what an 
important effect this great climatal cycle must have had 
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 othersinto 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 period suffi- 
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.2 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 fluminalis and Unio littoralis and of such 
mammalia as the hippopotamus and other great pachy- 
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 
depression 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. 


1 The Great Ice Age, p. 177. 

2 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. 

3 “Qn the Climate of the Post-Glacial Period.” Geological Magazine, 
1872, pp. 158, 160. 

4 Geological Magazine, 1876, p. 396. 


CHAP. VII 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, 

Paleontological Evidence of Alternate Cold and Warm 
Periods.—Kspecially 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 palzeolithic 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 Hlephas antiquus, Rhino- 
ceros hemitachus,.reindeer, bear, horse, and other quadru- 
peds, and with countless remains of the hyzenas which 
devoured them; while it has also been found in cave de- 
posits in Glamorganshire, at Durdham Down near Bristol, 
and in the post-Phocene 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 
quantity of vegetable food which it requires both indicate 
a much warmer climate than now prevails in any part of 
Kurope. 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 twoa 
little south-west of Mulhausen, whence it would easily 


120 ISLAND LIFE PART I 


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. 

“Tt 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 hyena 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, Jn some of the caverns, such as that 
of Kirkdale, the hyzena 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 
advancing 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 

1 Karly Man in Britain and his Place in the Tertiary Period, p. 113, 


CHAD. VII THE GLACIAL EPOCH 121 


_ 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 the 
existence of warm inter-glacial or post-glacial periods. 

Evidence of Interglacial Warm Periods on the Continent and 
in North America.—Besides the evidence already adduced 
from our own islands, many similar facts have been noted 
in other countries. In Switzerland two glacial periods are 
distinctly recognised, between which was a warm period 
when vegetation was so luxuriant as to form beds of lig- 
nite sufficiently thick to be worked for coal. The plants 
found in these deposits are similar to those now inhabiting 
Switzerland—pmes, oaks, birches, larch, etc., but numer- 
ous animal remains are also found, showing that the 
country was then inhabited by an elephant (lephas 
antiquus), a rhinoceros (Lhinoceros megarhinus), the urus 
(Gos primigenius), the red deer (Cervus elephas), and the 
cave-bear, (Ursus speleus); 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 upper one was deposited, but no interglacial 
deposits have yet been found. In North America more 
complete evidence has been obtained. On the shores of 
Lake Ontario sections are exposed showing three separate 
beds of “till” with intervening stratified deposits, the 
lower one of which has yielded many plant 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 unstratified “till” full 
of striated stones—six feet thick2 On the other side of 
the continent, in British Columbia, Mr. G. M. Dawson, 
geologist to the North American Boundary Commission, 


1 Heer’s Primeval World of Switzerland Vol. II., pp. 148-168, 
% Dr, James Geikie in Geological Magazine, 1878, p. 77, 


122 ISLAND LIFE PART 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 proof. that the 
elacial 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 would 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 by the 
Glacial Epoch—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 right in attributing the wonderful changes in 


CHAP. VII THE GLACIAL EPOCH 128 


animal and vegetable life that have occurred in Kurope 
and N. America between the Miocene Period and the 
present day, in part at least, to the two or more cold 
epochs that have probably intervened, These changes 
consist, first, in the extinction of a whole host of the higher 
animal forms, and secondly, in a complete change of types 
due to extinction and migration, leading to a much greater 
difference between the vegetable and animal forms of the 
eastern and western hemisphere than before existed. 
Many large and powerful mammalia lived in our own 
country in Pliocene times and apparently survived a part 
of the glacial epoch ; but when it finally passed away they 
too had disappeared, some having become altogether ex- 
tinct while others continued to exist im 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 
hyzena, bear, and lion, which are considered to be only 
varieties of those which once inhabited Britam. Down to 
Pliocene 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 pointed out 
that hundreds of species of trees and shrubs of peculiar 
genera which still flourish in those countries are now com- 
pletely wanting in Europe, 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; whereas 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 
migration into a milder region.! 


Our next two chapters will be devoted to a discussion 
of the causes which brought about the glacial epoch, and 
that still more extraordinary climatic phenomenon—the 


1 This subject is admirably discussed in Professor Asa Gray’s Lecture on 
** Forest Geography and Archeology” in the American Journal of Science 
and Arts, Vol. XVI. 1878. 


124 ISLAND LIFE PART I 


oe 


mild climate and luxuriant vegetation of the Arctic zone. 
If my readers will 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 justification for introducing such a discussion into 
the present volume. 

Note.—Readers who are especially interested in the 
question of the Glacial Epoch, its extent and work, espe- 
cially in connection with the formation of deep lake-basins, 
will find much new matter in the two chapters on “The 
Ice Age and its Work” in the first volume of my Studzves 
Scientific and Social, in which some new arguments founded 
on the surface and bottom contours of lake-basins are set 


forth. | 


CHAPTER VIII 


THE ‘CAUSES OF GLACIAL EPOCHS 


Various Suggested Causes—Astronomical Causes of Changes of Climate— 


Difference of Temperature caused by Varying Distance of the Sun— 
Properties of Air and Water, Snow and Ice, in Relation to Climate— 
Effects of Snow on Climate—High Land and Great Moisture Essential to 
the Initiation of a Glacial Epoch—Perpetual Snow nowhere Exists on 
Lowlands—Conditions Determining the 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 off the 
Sun’s Heat—South Temperate America as Illustrating the Influence of 
Astronomical Causes on Climate—Geographical Changes how far a 
Cause of Glaciation—Land acting asa Barrier to Ocean-currents—The 
theory of Interglacial Periods and their Probable Character—Probable 
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 Mars 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 other 


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 planet. 
2. Changes in the obliquity of the ecliptic. 
3. The combined effect of the precession of the equinoxes 


and of the excentricity of the earth’s orbit. 


4. Changes in the distribution of land and water. 


126 ISLAND LIFE PART IL 


5. Changes in the position of the earth’s axis of rota- 
tion. 

6. A variation in the amount of heat radiated by the 
sun. 

7. A variation in the temperature of space. 

Of the above, causes (1) and (2) are undoubted realities ; 
but it 1s 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—“Clmate and Time in their Geological 
Relations.” 

Astronomical Causes of Changes 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 


: CHAP. VIII THE CAUSES OF GLACIAL EPOCHS 127 


—_—_—_—— 


and we were also three million miles further 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 equinoxes 
and the motion of the aphelion) which actually brings this 
change about every 10,500 years, so that after this interval 
the condition of the two hemispheres is reversed as regards 
nearness to the gun 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 WINTE™ IN APHELION S .HEMISPHERE WINTER IN APHELION 


GLACIAL EPOCH IN CLACIAL EPOCH IN 
N.HEMISPHERE S.HEMISPHERE 


DIAGRAM 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 3 
AND ITS EFFECT ON CLIMATE DURING A PERIOD OF HIGH EXCENTRICITY. 


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 effects 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 high land 
around the 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 aphelion and perthelion 
there is another and still more important astronomical 


128 ISLAND LIFE PART I 


factor in the shwaite 8 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 was rather less than it 
is now, but it then increased, and when we come toa 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 perthelion (as the most distant and nearest 


PROBABLE DURATION OF THE GLACIAL Enon 


i 


Mt i 


300 250 200 


ii A 


THOUSAND YEARS iss FROM 
A.D.I 


————————————_ 
ie 


DIAGRAM OF EXCENTRICITY AND PRECESSION. 


The dark and light bands mark the phases of precession, the dark showing 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 


CHAP. VIII THE CAUSES OF GLACIAL EPOCHS 129 


years ago) the excentricity was very great, reaching a 
maximum of three and a half times its present amount at 
almost the remotest part of this period, at which time the 
length of summer in one hemisphere and of winter in the 
other would be 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 five 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 Temperature Caused by Varying Distances of 
the Sun.—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 degrees 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 temper- 
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+ 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 earth’s surface at any time is 50° F, it is really warmed 


K 


130 ISLAND LIFE > PARPT 


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 984 millions of miles, whereas it 
is now, in winter, only 914 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 would 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, 39, representing the amount which must be 
deducted to obtain the January temperature 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 produces 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 durmg our winter, 
at the time of the glacial epoch, the northern hemi- 
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. 


OHAP. VIII THE CAUSES OF GLACIAL EPOCHS 131 


a 


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 writers 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 30th, 1879, the Rev. O. Fisher calls 
attention to a result arrived at by Pouillet, that the temperature which 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 opinion, 
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 (which I have adopted) the differences 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 the 
adoption of Dr. Croll’s theory of the Astronomical and Physical causes of 
the Glacial Epoch. 

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 farthest in summer, whereas we calculate the temperatures of the 
glacial epoch for the phase of precession when the aphelion was in winter. 
A large part of the increase of temperature would no doubt be used up 
in melting ice and evaporating water, so that there would be a much less 
increase of sensible heat ; while only a portion of the theoretical lowering 
of temperature in winter would be actually produced owing to equalising 
effect of winds and currents, and the storing up of heat by the earth and 
ocean. } 


132 ISLAND LIFE PART I 


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 which often absorbs heat from the earth on which it 
falls, flows away in streams to the ocean; while the ocean 
itself, constantly impelled by the winds, forms great 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 up 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. VIII 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 surplus 
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 liquid 
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 hours 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, because it has no mobility. 
It remains where it fell and becomes compacted into a 
mass, and it then keeps the earth below it and the air 
above, at or near the freezing-point till it 1s all melted. If 
the quantity is great it may take days or weeks to melt ; 
and if snow continues falling it goes on accumulating all 
over the surface of a country (which water cannot do), and 
may thus form such a mass that the warmth of the 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 permanent, no amount of 


134 ISLAND LIFE wien 


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 few 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 two cubic feet 
to104°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 104° 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 104° 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 

1 Dr. Croll says this ‘‘is one of the most widespread and fundamental 


CHAP. 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 the extreme north 
of Asia and America where the winters are colder and the 
summers shorter than in Greenland in Lat. 62° N., or than 
in Heard Island and South Georgia, both in Lat, 53° 8. 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 Snow Nowhere Exists on Lowland Areas.—lIt 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 ;! 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 depend 
on the temperature of the air through which it falls. 

1 In an account of Prof. Nordenskjéld’s recent expedition round the 
northern coast of Asia, given in Natwre, November 20th, 1879, we have 
the following passage, fully supporting the statement in the text. ‘‘ Along 
the whole coast, from the White Sea to Behring’s Straits, no glacier was 
seen. During autumn the Siberian coast is nearly free of ice and snow. 
There are no mountains covered all the year round with snow, although 


136 ISLAND LIFE PART I 


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 everywhete exposed to the influence of moist 
sea-air ; and it is here, accordingly, that we find the nearest 
approach 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 the 
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, while 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 pole. 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 them 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 
Che Antarctic continent are probably lowlands or groups of islands. 
(Climate and Cosmology, Chap. V.) 


CHAP. VIII THE CAUSES OF GLACIAL EPOCHS 137 


in thickness.! As this is the thickness of the outer edge 
of the ice it must be far thicker inland ; and we thus find 
that the Antarctic continent is at this very time suffering 
glaciation to quite as great an extent as we have reason to 
believe occurred in the same latitudes of the northern 
hemisphere 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 floating 
icebergs. The much greater quantity of ice at the south 
pole is undoubtedly due to the presence 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 being 
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. 61°. 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 8. Lat. 53° 1s even now glaciated down to the sea. What 
would be its condition were it a northerly extension of a 
lofty Antarctic continent? We may be quite sure that 
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° 8. Lat. Even this is probably 
much too low an estimate, for on the west coast of New 
Zealand in 8. 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, we may 
be pretty sure that they would be nearly in the ice- 
covered condition of Greenland, although situated in the 
latitude of Marseilles. 


1 “On the Glacial Epoch,” by James Croll. Geol. Mag? July, August, 
1874. 


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Diagram of the approximate extent of Permanent and Floating Ice arou 


CHAP. VIII THE CAUSES OF GLACIAL EPOCHS 139 


Conditions Determining the Presence or Absence of Perpet- 
ual Snow.—It 1s 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 the 
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 m the very 
coldest portions of the two northern continents—EHastern 
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 with 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 
Kurope, 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.? 


1 “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-caps’ with which 
some authors in this country have amused themselves and their readers. 
Mr. Campbell, whose ability 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. W. Judd in Geol. Mag. 1876, p. 535.) 

The same author notes the diminution of marks of ice-action on going 
eastward in the Alps ; and the Altai Mountains far in Central Asia show 


140 ISLAND LIFE PART I 


in i a es. 


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. To 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 the country all 
the winter and spring, and is not sensibly diminished by 
the powerful sun so long as northerly winds keep the air 
below the freezing-point and occasional snow-storms 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 Producing 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 phenomena are strikingly 
in accordance with the theory here advocated, of the absolute dependence 


of glaciation on abundant rainfall and elevated snow-condensers and 
accumulators, 


CHAP. VIII THE CAUSES OF GLACIAL EPOCHS 141 


ee 


high degree of excentricity and a winter in aphelion. 
When 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 1t 1s now, and, according 
to Dr. Croll’s calculations, the mid-winter temperature of 
the northern hemisphere would have been lowered 36° F., 
while the winter half of the year would have been twenty- 
six days longer than the summer half. This would bring 
the January mean temperature of England and Scotland 
almost down to zero or about 30° F. 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 not 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 answer 
that it would. Sir Charles Lyell maintained that it 
would only do so if geographical conditions were then 
more favourable than they are now; while the late Mr. 
Belt has argued, that excentricity alone would not produce 
the effect 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 extent that snow and ice would be formed in the 
Arctic and Antarctic regions at the same time whether 
the winter were in perihelion or aphelion.: 

The problem we have now to solve is a very difficult one, 
because we have no case at all parallel to it from which 
we can draw direct conclusions. It 1s, 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 aphelion during that season, would 
not of itself produce a glacial epoch unless the amount of 


1 I have somewhat modified this whole passage in the endeavour to 
represent more accurately the difference between the views of Dr. Crolland 
Sir Charles Lyell. 


142 . JSLAWD LIFE | PART I 


vapour supplied for condensation was also exceptionally 
great. The greatest quantity of snow falls in the Arctic 
regions in summer and autumn, and with us the 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 sprmg and summer vapours, 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 Causes in intensifying Glaciation. 
—The trade-winds owe their existence to the great differ- 
ence between the temperature of the equator and the 
poles, which 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 perihelion, 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 proportion, 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 way. The increase of snow and ice in the 
northern hemisphere is the cause of an increased supply of 
moisture being brought by the more powerful anti-trades, 
and this greater supply of moisture leads to an extension 
of the ice, which reacts in still further increasing the 
supply of moisture.. The same increase of snow and ice, 
by causing the north-east to be stronger than the south-east 


144 ISLAND LIFE PART I 


trade-winds, diminishes the force of the Gulf Stream, and 
this diminution lowers the temperature of the North 
Atlantic both in summer and winter, and thus helps on 
still further the formation and perpetuation of the icy 
mantle. It must also be remembered that these agencies 
are at the same time acting in a reverse way in the 
southern hemisphere, diminishing the 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 Principal 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 aphelion), 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 apparent 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 ice; and, in the second place, 
because the two great heat-distributing agencies, the 
winds and the ocean-currents, are so affected by an 
increase of the snow and ice towards one pole and its 
diminution towards the other, as to help on the process 
when it has once begun, and by their action and reaction 
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 toa 
much greater degree than do land or water. The heat, 
therefore, of the short summer would have far less effect 
than is due to its calculated amount in melting the snow, 
because so much of it would be lost by reflection. A 


CHAP. VIII THE CAUSES OF GLACIAL EPOCHS 145 


portion of the reflected heat would no doubt warm 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 again, 
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 sonie of its heat to the surrounding air ; but 
that air still remains below the freezing point 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, which 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. 

Lffect of Clouds and Fog in cutting off the Sun’s 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 
proportion of the sun-heat and prevent it reaching the 
surface of the earth; and such a cloudy atmosphere would 
be a necessary result of large areas of high land covered 
with snow and ice. That such a prevalence of fogs and 
cloud is an actual fact in all ice-clad countries has been 
shown by Dr. Croll most conclusively, and he has further 

L 


146 ISLAND LIFE PART ] 


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), for the clouded sky seldom allows the sun to warm 
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 phenomenon accom- 
panying the presence of large masses of ice in every part 
of the world.? 

In reply to the objections of a recent critic Dr. Croll 
has given a new proof of this important fact by comparing 
the known amount of snow-fall with the equally well- 
known 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 


1 For numerous details and illustrations see the paper—‘‘On Ocean 
Currents in Relation to the Physical Theory of Secular Changes of Climate” 
—in the Philosophical Magazine, 1870. 


CHAP. VIII THE CAUSES OF GLACIAL EPOCHS 147 


equator from sunrise to sunset, if none were cut off by the 
atmosphere, would melt 34 inches of ice, or 100 feet in a 
year. The quantity received between latitude 60° and 80°, 
which is that of Greenland, is, according to Meech, one- -half 
that received at the equator. The heat received by 
Greenland from the sun, if none were cut off by the 
atmosphere, 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 the Influence of 
Astronomical Causes on Climate-—Those persons who still 
doubt the effect of winter in aphelion with 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 
things to which 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 1s now a moderate amount of 
excentricity, and the winter of the southern hemisphere is 
in aphelion? The mere geographical position of the 
southern extremity of America does not seem especially 
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 


1 See Darwin’s Naturalist’s Voyage Round the World, 2nd Edition, pp. 
244-251. 
L 2 


148 ISLAND LIFE PART I 


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 compared 
with the same season in the northern hemisphere. The 
only important differences are: the open 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 upon 
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 prevail to so great 
an extent in the northern hemisphere during the glacial 
epoch, as they do in the southern hemisphere at the 
present 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. 
Geographical Changes, how far a Cause of Glaciation.— 
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 impossible, 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 


CHAP. VIII THE CAUSES OF GLACIAL EPOCHS 149 


would result from 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 whole earth 
should thoretically be at a somewhat higher temperature. 
Two main causes would bring about this glaciation. A 
very large area of elevated land in high latitudes would act 
as a powerful condenser of the 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 would 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 Principles of 
Geology (11th ed.Vol.i. p. 270), if somewhat modified so as 
to allow a freer passage of currents in the tropics, do really 
exhibit a condition of the earth which, by geographical 
changes alone, would bring about a perpetual summer or an 
almost universal winter. But we have seen in our sixth 
chapter that there is the strongest cumulative evidence, 


150 ISLAND LIFE PART I 


almost amounting to demonstration, that for all known 
geological periods 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 clear 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 bLarrvr 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 shght 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 would 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 might 
raise the temperature 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 influence 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, thé 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 PART I 


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 Probable 
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 


1 The influence of geographical changes on climate is now held by 
many geologists who oppose what they consider the extravagant hypotheses 
of Dr. Croll. Thus, Prof. Dana imputes the 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 Paleozoic, 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 preponderating effect in the oscillating agency of 
all time—lateral pressure within the crust.” (American Journal 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 Geology, 2nd Edition, pp. 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 probable. 
Such are the interglacial deposits indicating a mild climate, 
both in Europe and America; an early phase of very 
severe glaciation when the “till” was deposited, with 
later less extensive glaciation when moraines were left in 
the valleys; several successive periods of submergence and 
elevation, the later ones becoming less and less in amount, 
as indicated by the raised beaches slightly elevated above 
our present coast line; and lastly, the occurrence in the 
same deposits of animal remains indicating both a warm 
and a cold climate, and especially the existence of the 
hippopotamus in Yorkshire not long after the period of 
extreme glaciation. 

But although the evidence of some alternations of climate 
seems indisputable, and no suggestion of any adequate 
cause for them other than the alternating phases of 
precession during high 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 whole year. 
It is quite evident that during the height of the glacial 
epoch there was a combination of causes at work which led 
to a 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 we must reckon a 
diminution of the force of the Gulf Stream, or its being 
diverted from the north-western 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 tf the ocean currents remained the 
same. The force of these currents is, it 1s 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 PART I 


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.1 This elevation would 
bring the wide area of the banks of Newfoundland far 
above water, causing the American coast to stretch out in 
an immense curve to a point more than 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, 2nd Edition, p. 540, 


CHAP, VIII THE CAUSES OF GLACIAL EPOCHS 155 


Spain. The consequence of such a state of things would 
probably be that the southward flowing Arctic currents 
would be much reduced in velocity; and the enormous 

uantity of icebergs continually produced by the ice-sheets 
of allthe lands bordering the North Atlantic would hang 
about their shores and the adjacent seas, filling them with 
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—the physical and geographical 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 powerful sun did 
during the phase of summer in perthelion, while 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 would ever 
occur), then the ice-sheet will not be removed during the 
alternate phases of precession, so long as these geographical 
and physical causes remain unaltered. It is true that the 
warm and cold oceanic currents, which are the most 
important agents in increasing or diminishing glaciation, 
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.! 


1 Dr. Croll says that I here assume an impossible state of things. He 
maintains ‘‘ that the change from the distant sun in winter, and near sun 


156 ISLAND LIFE PART I 


If this argument 1s 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 the probable effect of the 
change in precession during the next period of 10,500 
years, with the present moderate degree of excentricity. 

Probable Effect of Winter in Aphelicn 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 effect 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.) Thisseems 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 difference 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. 


oma. vit THE CAUSES OF GLACIAL EPOCHS 157 


summers being proportionately shorter and hotter, without 
any other change whatever. The long cold winter would 
certainly bring down the snow-line considerably, covering 
large areas of high land with snow during the winter 
months, and causing all glaciers and ice-fields to become 
larger. This would chill the superincumbent atmosphere 
to such an extent that the warm sun and winds of spring 
and early summer would bring clouds and fog, so that the 
sun-heat would be cut off and much vapour be condensed 
assnow. ‘The greater sun-heat of summer would no doubt 
considerably reduce the snow and ice; but it is, I think, 
quite certain that the extra accumulation would not be all 
melted, and that therefore the snow-line would be 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 aphelion (instead 
of, as now, in perthelion), 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 1s In now (all geographical and physical 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 tops covered 
with perpetual snow. This perpetual snow, down to a 
fixed line, would be kept up by the needful supply of snow 
falling during autumn, winter, and spring, and this would, 
as we have seen, depend mainly on the increased length 
and greatly increased cold of the winter. As both the dura- 
tion and the cold of winter decreased the amount of snow 
would certainly decrease, and of this lesser quantity of snow 


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 both the winds and currents, in the manner 
already explained (sce 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 Principle of Clumatal 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 will 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 


onar. vir 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 will, to some extent 
apply, inversely, with mild Arctic climates; but this is a 
subject which will be discussed in the next chapter. 

This view of the character of the last glacial epoch 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 very latest 


160 ISLAND LIFE PART I 


of them, which we may suppose to have occurred when the 
excentricity was considerably diminished, that exhibit any 
indications of a climate at all warmer than that which now 
prevails.? 

Probable Date of the Glacial Epoch.—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, 


1 In the Geological Magazine, April, 1880, Mr. Searles 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 proportion 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 complete 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) partly 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 difference 
indicated by the ice-extension in the two countries so great as the present 
difference of winter-temperature, which 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 we must go twenty degrees further south in 
the former country to obtain the same mean winter-temperature we find 
in the latter, as may be seen by examining any map of winter isothermals. 
This difference very fairly corresponds to the difference of conditions 
existing during the glacial epoch and the present time, so far as we are 
able to estimate them, and it certainly affords no grounds of objection to 
the theory by which the glaciation is here explained. 


CHAP.:VIII THE CAUSES OF GLACIAL EPOCHS 161 


while on the other hand the surface markings produced 
by the ice have been extensively preserved ; and taking 
all these facts into. consideration, the period of about 
200,000 years since it reached its maximum, and about 
80,000 years since it passed away, is generally considered 
by geologists to be 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.—lt 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 have generally admitted that the cause is a 
real one, and must have produced some effect of the kind 
indicated. It is evident that if ice-sheets several miles in 
thickness were removed from one polar area and placed on 
the other, the centre of gravity of the earth would shift 
towards the heavier pole, and the sea would necessarily 
follow it, and would rise accordingly. Extreme glacialists 
have maintained that during the height of the glacial 
epoch, an ice-cap extended from about 50° N. Lat. in 
Kurope, 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 the 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, how- 
ever, Shown that the production of any such ice-cap is 
improbable if not impossible, because snow and ice can 

M 


162. 7 ISLAND LIFE PART I 


only accumulate where precipitation is greater than melt- 
ing and evaporation, 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 limitation, 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 earth 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 in perthelion or aphelron. 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 same 
time as in the northern, unless changed geographical condi- 
tions, of which we have no evidence whatever, 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.’ 

1 Dr. Croll objects to this argument, and adduces the case of Greenland 
as showing that ice may accumulate far from sea. But the 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 New Zealand is generally imputed by 
the local geologists to a greater elevation of the land; but I cannot help 


——— 


a. 
ra 


CHAP. VIII THE CAUSES OF GLACIAL EPOCHS 163 


__- oe 


This greater accumulation of ice in both hemispheres 
would lower the whole ocean by the quantity of water 


believing that the high phase of excentricity which caused our own glacial 
epoch was at all events an assisting cause. This is rendered more prob- 
able if taken in connection with the following very definite statement of 
glacial markings in South Africa. Captain Aylward in his Transvaal of 
To-day (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 passage is evidently written by a person 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 offering 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 much 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, situated as they are between 27° and 30° S. Lat. ; 
since the Andes, which in 32°S. Lat. reach 23,300 feet high, and in 28° 
S. Lat. 20,000, with far more extensive plateaus, produce no ice-fields. 
We cannot, therefore, believe that a few 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 believe that it was mainly due to the same high excentricity that led to 
the glaciation of Western and Central Europe, and Eastern North America. 
_ These observations confirm those of Mr. G. W. Stow, who, in a paper 
published in the Quarterly Jowrnal of the Geological Society (Vol. XXVII. p. 
539), describes similar phenomena in the same mountains, and also mounds 
and ridges of unstratified clay packed with angular boulders ; while 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 phenomena characteristic of a glaciated country, only 
a few degrees south of the tropic ; and taken in connection with the indica- 
tions of recent glaciation in New Zealand, and those discovered by Dr. R. 
von Lendenfeld in the Australian Alps between, 6,000 and 7,000 feet ele- 
vation (Nature, Vol. xxxtI. p. 69), we can hardly doubt the occurrence of 
some general and wide-spread cause of glaciation in the southern hemisphere 
at a period so recent that the superficial phenomena are almost as well pre- 
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 Mount Kenya 5,000 feet below their present limits, renders probable 
the former glaciation of the South African Highlands. . f 


M 2? 


164 ISLAND LIFE PART i 


abstracted from it, while any want of perfect synchronism 
between the decrease of the ice at the two poles would 
cause a movement of the centre of gravity of the earth, 
and a slight rise of the sea-level at one pole and depression 
at the 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 very 
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 - 
Excentricity as a Cause of Glacial Periods—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, however, 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 power 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 way 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 with the supposed polar snows of 
Mars.! 


1 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 by Mars 
on the Subject of Glacial Periods,” but I arrive at somewhat different con- 
clusions from those of the writer of the paper. 


omar. vill THE CAUSES OF GLACIAL EPOCHS 165 


Mars offers an excellent subject for comparison with the 
Earth as regards this question, because its excentricity. is 
now a little greater than the maximum excentricity of the 
Earth during the last million years,——(Mars excentricity 
0:0931, Earth excentricity, 850,000 years back, 0:0707); 
the inclination of its axis is also a little greater than ours 
(Mars 28° 51’, Earth 23° 27’), and both Mars and the Earth 
are so situated that they now have the winter of their 
northern hemispheres in perthelion, that of their southern 
hemisphere being in aphelion. If, therefore, the physical 
condition of Mars were the same or nearly the same as that 
of the Earth, all circumstances combine, according to Dr. 
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. Asa matter of fact 
Mars has two snow-caps, of nearly equal magnitude at their 
maximum in winter, but varying very unequally. The 
northern cap varies slowly and little, the southern varies 
rapidly and largely. 

In the year 1830 the sowthern snow was observed, during 
the midsummer of Mars, to diminish to half its former 
diameter in a fortnight (the duration of such phenomena 
on Mars being reckoned in Martian months equivalent to 
one-twelfth of a Martian year). Thus on June 28rd it 
was 11° 30’ in diameter, and on July 9th had diminished 
to 5° 46’, after which it rapidly increased again. In 1837 
the same cap was observed near its maximum in winter, 
and was found to be about 35° in diameter. 

In the same year the northern snow-cap was observed 
during its summer, and was found to vary as follows :-— 


May 4th. Diameter of spot ~* 31° 24’ 
June 4th. - - 23°: Of 
ve Vth: . s 22° 54’ 
July 4th. eS - 18° 24’ 
,, 12th. ss B: 15° 20’ 
»» 20th. : a 18° 0’ 


We thus see that Mars has two permanent snow-caps, of 
nearly equal size in winter but diminishing very unequally 


166 ISLAND LIFE . PARTI 


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 Earth 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 
hemisphere of eight degrees wide (about 280 miles) be- 
tween May 4th and July 12th. Even with our much 
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 informed 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, we may be 


1 Inanarticlein Nature of Jan. 1, 1880, the Rey. T. W. Webb states that 
in 1877 the pole of Mars (? the south pole) was, according to Schiaparelli, 
entirely free of snow. He remarks also on the regular contour of the sup- 
posed snows of Mars as offering a great contrast to ours, and also the 
strongly marked dark border which has often been observed. Onthe 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 GLACIAL EPOCHS 167 


sure that the snow (if it is real snow) is much less thick 
—a mere surface-coating in fact, such as occurs in parts 
of Russia where the precipitation is less, and the snow 
accordingly does not exceed two or three feet in thickness. 

We now see the reason why the southern pole of Mars 
parts with its white covering so much more quickly and to 
so much greater an extent than the northern, for the south 
pole during summer is nearest the sun, and, owing to the 
great excentricity of Mars, would have about one-third 
more heat than during the summer of the northern hemi- 
sphere ; and this greater heat would cause the winds from 
the equator 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 the 
influence of excentricity, and that of winter in perthelion 
in the northern, and summer in perihelion 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 
descending to the level of the sea, and constant snowstorms 


168 ISLAND LIFE PART I 


in the height of summer, although the sun is then actually 
nearer the earth than it is during our northern summer ! 
It is evident, therefore, that the phenomena presented 
by the varying polar snows of Mars are in no way opposed 
to that modification of Dr. Croll’s theory of the conditions 
which brought about the glacial epochs of our northern 
hemisphere, which is here advocated; but are perfectly 
explicable on the same general principles, if we keep in 
mind the distinction 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 within the small circles of perpetual polar 
snow there can at the present time be no ice-sheets in 
Mars ; and the reason why this permanent snowy area is 
more extensive around the northern than around the 
southern pole may be partly due to higher land at the 
north, but is perhaps sufficiently explamed 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 during the long night of winter. 


eS yy 
‘ 7 


CHAPTER IX 


ANCIENT GLACIAL EPOCHS, AND MILD CLIMATES IN THE 
ARCTIC REGIONS 


Dr. 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 Evi- 
dence—Temperate Climates in the Arctic Regions—The Miocene Arctic 
Flora—Mild Arctic Climates of the Cretaceous Period—Stratigraphical 
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 
—KEffect of High Excentricity on Warm Polar Climates—Evidences as to 
Climate in the Secondary and Paleozoic Epochs—Warm Arctic Climates 
in Early Secondary and Palzozoic Times—Conclusions as to the Climates 
of Secondary and Tertiary Periods—General View of Geological Climates 
as Dependent on the Physical Features of the Earth’s Surface—Estimate 
of the Comparative Effects of Geographical and Physical Causes in Pro- 
ducing Changes of Climate. 


IF we adopt the view set forth in the preceding chapter as 
to the character of the glacial epoch and of the accom- 
panying alternations of climate, it must have been a very 
important agent in producing changes in the distribution 
of animal and vegetable life. The imtervening mild 
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. During the four or five 


170 ISLAND LIFE PART I 


thousand years that each specially mild period may have 
lasted, some portions of the north temperate zone, which 
had been buried in snow or ice, would become again 
clothed with vegetation and stocked with animal life, both 
of which, as the cold again came on, would be driven 
southward, or perhaps partially exterminated. Forms 
usually separated would thus be crowded together, and a 
struggle for existence would 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 would spread and multiply; and after this had 
gone on for thousands 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. Croll 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 
time 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 excentricity 
coincided with some part of the latter period ; and Dr. 
Croll maintains that a glacial epoch must then have 


1 London, Edinburgh and Dublin Philosophical Magazine, Vol. XXXVI., 
pp. 144-150 (1868). 


occurred surpassing in severity 
that of which we have such con- 
q -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 
may 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 
high excentricities greatly 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 would inevitably 
produce glaciation in one hemi- 
sphere, and a_ proportionately 
mild and equable climate in the 
opposite hemisphere, then we 
should have to look for evidence 
of exceptionally warm and excep- 
tionally cold periods, occurring 


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DIAGRAM SHOWING THE CHANGES OF EXCENTRICITY DURING THE LAST THREE MILLION YEARS. 


172 ISLAND LIFE PART I 


alternately and with several repetitions, within a space of 
time which, geologically speaking, is very short indeed. 

Let us then inquire 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 Evidence of Remote 
Glacial 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. Croll and other writers have 
ably argued that no such evidence is likely to be found. 
It is now generally admitted that sub-aérial 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 diff- 
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 im 
- 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. The details of these measurements will be given 
in a future chapter, and it is only necessary here to state 
that the average of them all gives 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 


CHAP. IX ANCIENT GLACIAL EPOCHS 173 


years to remove one foot ; while the Po is the most rapid, 
taking only 729 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 ma low forest-clad plateau. The Po, 
on the other hand, is wholly in a district of abundant rain- 
fall, while its sources are spread over a great amphitheatre 
of snowy Alps nearly 400 miles in extent, where the 
denuding forces are at a maximum. As Scotland is a 
mountain region of rather abundant rainfall, the denuding 
power of its rains and rivers is probably rather above than 
under the average, but to avoid any possible exaggeration 
we will take it ata foot m 4,000 years. 

Now if the end of the glacial epoch be taken to coin- 
cide with the termination of the last period of high 
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 wherever the rivers have spread during 
floods, the ground will have been raised instead of lowered ; 
and on all nearly level ground and gentle slopes there 
will have been comparatively little denudation; so that 
proportionally much more must have been taken away 
from mountain sides and from the bottoms of valleys 
having a considerable downward slope. One of the very 
highest authorities on the subject of denudation, Mr. 
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 widened on 
the average about five feet in the 4,000 years instead of 
one foot ; and thus many valleys must have been deepened 
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 us the followmg account of the 
present aspect of the surface of a large part of the coun- 
iy 

Go where one will in the lowlands of Scotland and he 
shall hardly find a single acre whose upper surface bears 
the marks of being formed by the denuding agents now in 
operation. He will observe everywhere mounds and 
hollows which cannot be accounted for by the present 
agencies at work. . . . In regard to the general 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 preservation of the glaciated sur- 
face. The amount of average denudation, however, 1s 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 the last glacial epoch, 
it becomes evident that any surface-phenomena produced 
by still earlier glacial epochs must have long since entirely 
disappeared. | 

Lise of the Sea-level Connected with Glacial Epochs, a Cause 
of Further 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 in the same areas during the Tertiary epoch, and 
some writers connect these subsidences with the glacial 

1 Climate and Time in their Geological Relations, p. 341. 


~ CHAP. IX ANCIENT GLACIAL EPOCHS 175 


period itself, the unequal amount of ice at the two poles 
causing the centre of gravity of the earth to be displaced 
when, of course, the surface of the ocean will conform to it 
and appear to rise in the one hemisphere 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 cold 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, 
which would react on the accumulation of snow and ice, 
and thus add ayother 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 any 
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-aérial and marine denudation, would undoubtedly 
destroy all those superficial evidences of ice-action on 
which we mainly depend for proofs of the occurrence of the 
last glacial epoch. 

What Evidence of Early Glacial Epochs may be 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 
practically indestructible. 

One of the most constant of all the phenomena of a 
glaciated country is the abundance of icebergs produced by 
the breaking off of the ends of glaciers which terminate 


176 ISLAND LIFE PART I 


in arms of the sea, or of the terminal face of the ice-sheet 
which passes beyond the land into the ocean. In both 
these cases abundance of rocks and débris, 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 with the 
ice and form a deposit of marine “ till” near the shore. 

It has indeed been objected that when an _ ice-sheet 
covered an entire country there would be no moraines, and 
that rocks or débris 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 débris ; and as the ice-sheet spreads, 
and again as it passes away, this moraine-forming area 
will successively occupy 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 ; 1 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 throughout the greater 
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 

1 Nature, Vol. XXI., p. 345, ‘‘ The Interior of Greenland.” 


CHAP. IX ANCIENT GLACIAL EPOCHS vi. 


the rocks and carried out to sea by the glaciers themselves. 
Moreover, as icebergs float far beyond the limits of the 
countries which gave them birth, these ice-borne materials 
would be largely imbedded in deposits forming from the 
denudation of countries which had never been glaciated, or 
from which the ice had already disappeared. 

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 
would 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 epoch. 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 million 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 


178 ISLAND LIFE PART I 


theory of repeated glacial epochs during the Tertiary 
period. 

Hvidences of Ice-action during the Tertiary Period —The 
Tertiary fossils both of Europe and North America indicate 
throughout warm or temperate climates, except those of 
the more recent Pliocene deposits which merge into the 
earlier 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 Cycadacee, 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, 


OMAP. Ix ANCIENT GLACIAL EPOCHS 179 


and forty-five feet thick! The granite is red, and of a 
peculiar kind which cannot be matched anywhere in the 
Alps, or indeed elsewhere. Similar erratics have also been 
found in beds of the same age in the Carpathians and in 
the Apennines, indicating probably an extensive inland 
Kuropean sea into which glaciers descended from the sur- 
rounding mountains, depositing these erratics, and cooling 
the water so as to destroy the mollusca 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 
degree a measure as well as a proof. It is not therefore 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 Hvidence-— But when we 
proceed to examine the Tertiary deposits of other parts of 


1 Prof. J. W. Judd says: ‘‘In the case 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 supplies for the glaciers protruded into 
surrounding plains. And when we survey the grand panoramas of ridges, 
pinnacles, and peaks produced for the most part by sub-aérial 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. 5386.) 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 blocks were de- 
posited on the Jura and the great moraincs formed in North Italy, as this 
theory would imply. We can hardly suppose 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 such 
an extension of the snow-fields would alone suffice for the effects which were 
certainly produced. 


N 2 


180 ISLAND LIFE PART I 


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 V. 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 mnumerable; 
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 England a glacial 
period could have occurred without its evidences being 


OHAP. IX MILD ARCTIC CLIMATES 181 


—_———— 


abundantly apparent. The Oligocene of Northern Ger- 
many and Belgium, and the Miocene of those countries 
and of France, have also afforded a rich molluscan fauna, 
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 we have 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 help 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 
interglacial 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. 

Temperate Climates in the Arctic Regions—As we have 
just seen, the geological evidence of the persistence of sub- 
tropical or warm climates in the north temperate zone 
during the 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 the Arctic 
zone, and into countries now almost wholly buried in snow 
and ice. These warm Arctic climates have been explained 
by Dr. Croll as due to periods of high excentricity with 
winter in perihelion, a theory which implies alternating 

1 Geological Magazine, 1876, p. 392 


182 ISLAND LIFE PART I 


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 754° N. Lat. the trunk and root 
ofa fir tree which had apparently 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 plentifully in the bed of a river which 
runs through Reindeer Valley at Cape Thordsen. They 


1 Colonel Fielden thinks that these trees have all been brought down 
by rivers, and have been stranded on shores which have been recently 
elevated. See Trans. of Norfolk Nat. Hist. Soc., Vol. LIf., 1880. 


4 
‘ 


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, has been hollowed out by 
glacial action.” 

The 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 EKurope 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 corresponding 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, found 
chiefly at Gininghen in the northern extremity of Switzer- 
land, 465 species are known, of which 166 species are 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 70° N. Lat. 
we find abundant remains of a flora of the same general 


Geological Magazine, 1876, ‘‘ Geology of Spitzbergen,” p. 267. 


184 ISLAND LIFE PART I 


type as that of Gininghen but of amore northern character. 
We have a sequoia identical with one of the species found 
at Qininghen, a chestnut, salisburia, liquidambar, sas- 
safras, and even a magnolia. We have also seven species 
of oaks, two planes, two vines, three beeches, four poplars, 
two willows, a walnut, a plum, 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 coniferz, one of | 
which is identical with the swamp-cypress (TZaxodiwm 
distichum) now found living in the Southern United States ! 
There are also eleven pines, two Libocedrus, two sequoias, 
with oaks, poplars, birches, planes, limes, a hazel, an ash, 
and a walnut; also water-lilies, pond-weeds, and an iris— 
altogether about a hundred species of flowering plants. 
Even in Grinnell Land, within 8} degrees of the pole, a 
similar flora existed, twenty-five species 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 abies) which last does not now extend beyond 
694° N. | 

Fossil plants closely resembling those just mentioned 
have been found: at many other Arctic localities, especially 
in Iceland, on the Mackenzie River in 65° 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 little further south, near 
Breslau, north of the Carpathians, a rich flora has been 
found allied to that of ininghen, but wanting in some of the 
more tropical forms. Again, in the Isle of Mull in Scotland, 
in about 564° N, Lat., a plant-bed has been discovered con- 


_ CHAP. IX MILD ARCTIC CLIMATES 185 


taining 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 CEninghen and Spitzbergen, but the great ma- 
jority being distinct, and exhibiting decided indications 
of a decrease of temperature according to latitude, though 
much less in amount than now exists. Some writers have 
thought that the great similarity of the floras of Greenland 
and(ininghen 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 Kucalyptus, 
Acacia, Casuarina, Stylidium, Goodenia, and many other 
genera would certainly form a prominent feature in any 
fossil flora now being preserved. 

Mild Arctic Climates of the Cretaceous Period.—In the 
Upper 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 have been identi- 
fied, of which there are fifteen ferns, two cycads, eleven 
conifer, three monocotyledons, and thirty-four dicotyledons. 
One of the ferns is a tree-fern with thick stems, which has 
also been found in the Upper Greensand of England. 
Among the conifers the giant sequoias are found, and among 


186 ISLAND LIFE PART I 
the dicotyledons the genera Populus, Myrica, Ficus, Sassa- 
fras, Andromeda, Diospyros, Myrsine, Panax, as well as 
magnolias, myrtles, and leguminose. Several of these 
groups 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 
whole, there seems to be less difference between the floras 
of Arctic and temperate latitudes in Upper Cretaceous 
than in Miocene times. 

In the same locality in Greenland (70° 33’ N. Lat. and 
52° W. Long.), and also in 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 the genus 
Sequoia, one of which 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 Upper 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, therefore, that these 
Lower Cretaceous plants represent local peculiarities of 


1 The preceding account is mostly derived from Professor Heer’s great 
work Flora Fossilis Arctica, 


CHAP. Ix MILD ARCTIC CLIMATES 187 


vegetation such as now sometimes occur in tropical 
countries. On sandy or coralline islands in the Malay 
Archipelago there will often be found a vegetation con- 
sisting almost wholly of cycads, pandani, and palms, while 
a few miles off, 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 de- 
tritus of some adjacent river, while not only would the 
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 floated 
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 facts 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 within the 
Arctic circle, yet nowhere has any proof been obtained of 
intercalated cold periods, such as would be indicated by 
the remains of a stunted vegetation, or a molluscan fauna 
similar to that which now prevails there. 

Stratigraphical Evidence of Long-Continued Mild Arctic 
Conditions.—Let usnow 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 perhaps the greatest living authority on Arctic geology 
—Professor Nordenskjold. In his lecture on “The Former 
Climate of the Polar Regions,” he says: “The character 
of the coasts in the Arctic regions is especially favourable 
to geological investigations. While the valleys are for the 


188 ISLAND LIFE PART 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 everywhere expose 
their bare surfaces to the investigator. The knowledge 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, skow 
no signs of aglacial 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, enjoyed a magnificent climate, which 
indeed was somewhat colder during the Miocene period, 
but was 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 
1 Geological Magazine, 1875, p. 531. 


CHAP. IX MILD ARCTIC CLIMATES 189 


by intervals of ancient glacial periods. The profilesI have. 
had the opportunity to examine during my various Spitz- 
bergen expeditions would certainly, if laid down on a line, 
occupy an extent of a thousand English miles ; 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 other 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, both in 
space and time, it is derived from the work of the most 
competent living geologists, and it is absolutely consistent 
in itsgeneral tendency. 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.” 


1 Geological Magazine, 1876, p. 266. In his recent work—Climate and 
Cosmology (pp. 164, 172)—the late Dr. Croll has appealed to the imperfection 
of the geological record as a reply to these arguments ; in this case, 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 that of the following Eocene period. Mr. De Rance (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 Kocenes occur types of 
plants 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 their advent in Europe. These plants 
point to a far higher mean temperature than those of the Dakota group, 
to a dense atmosphere of vapour, and a luxuriance of ferns and palms.” 
This is very important as adding further proof to the view that the 


190 ISLAND LIFE PART I 


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 whose 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 upon 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 warm 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 we can hardly form a 
conception, A great amelioration of climate would also 
be caused by the breaking up or the lowering of such 


climates of former 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 accumulation of ice ; 
while the interpenetration of the sea into any part of the 
great continents in the tropical or temperate zones would 
again tend to raise the winter temperature, 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 1s, 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 purpose 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. 

Geographical Changes Favouring Mild Northern Climates 
in Tertiary Times—The distribution of the Eocene and 
Miocene formations shows, that during a considerable 
portion of the Tertiary period, an inland sea, more or less 
occupied by an archipelago of islands, extended across 
Central Europe between the Baltic and the Black and 
Caspian Seas, and thence by 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 period. Another 
channel probably existed over Egypt’ into the eastern 


1 Mr. S. B. J. Skertchley informs me that he has himself observed thick 
Tertiary deposits, consisting of clays and anhydrous gypsum, at Berenice 
on the borders of Egypt and Nubia, at a height of about 600 feet above the 
sea-level ; but these may have been of fresh-water origin. 


192 ISLAND LIFE PART I 


basin of the Mediterranean and the Black Sea; while it is 
probable that there was a communication between the 
Baltic and the White Sea, leaving Scandinavia as an 
extensive island. Turning to India, we 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 by the presence of marine fossils of 
Kocene 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 may 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 were deposited were always more extensive 
than the fragments-of those strata now existing, and often 
immensely more extensive. The Eocene deposits of 
Europe, for example, have certainly undergone enormous 
denudation both marine and subaérial, and may have once 
covered areas where we now find older deposits (as the 
chalk once covered the weald), while a portion of them 
may lie concealed under Miocene, Pliocene, or recent beds, 
We find them widely scattered over Europe and Asia, and 
often elevated into lofty mountain ranges ; and we should 
certainly err far more seriously in confining the Eocene 
seas to the exact areas where we now find Eocene rocks, 
than in liberally extending them, so as to connect the 
several detached portions of the formation whenever there 
is no valid argument against our doing so. Considering 
then, that some one or more of the sea-communications 
here indicated almost certainly existed during Eocene and 
Miocene times, let us endeavour to estimate the probable 
effect such communications would have upon the climate 
of the northern hemisphere. 

The Indian Ocean as a Source of Heat in Tertiary Times. 
—If we compare the Indian Ocean with the South 
Atlantic we shall see that the position and outline of the 
former are very favourable for the accumulation of a large 
body of warm water moving northwards. Its southern 


HAP. Ix MILD ARCTIC CLIMATES 133 


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, 
7 st where the two great channels above described formed 
n outlet to the northern seas. As will be shown im our 
7 meteenth chapter, there was probably, during the earlier 
portion of the Tertiary period at least, several large islands 
in the space between Madagascar and South India; bat 
F these had wide and deep channels between them, and 
their existence may have been favourable to the con- 
of heated water northward, by concentrating 
the currents, and thus producing massive bodies of moving 
water analogous to the Gulf Stream of the Ailantic? 
Less heat would thus be lost by evaporation and radiation 
im the tropical zone, and an impulse would be acquired 
which would carry the warm water into the north polar 
varea. About the same period Australia was probably 
_ divided into two islands, separated by a wide channel in > 
‘north and south direction (see Chapter XXIL),. 
through this another current would almost atabalya as 
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 probable fertility of the 
_ Central Asiatic plateau, would lead to the Indian Ocean 
being traversed by regular trede-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 Céntral Europe and Western and Northern Asia. 
s to the warm currents being concentrated in inland 
s instead of being dispersed over a wide ocean like the 


2 ee ns our map of the Indian Ocean showing the submarine 
by ancient islands (Chap. XIX.), it will be evident that the 
ae Sth east trade-winds—then exceptionally powerful—would cause a vast 
y of water to enter the deep Arabian Sea. 

oO 


194 ISLAND LIFE PART I 
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 imter-penetrated 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 parts of Europe might then have enjoyed a 
climate fully equal to that of the warmer parts of New 
Zealand at the present day, and might have well supported 
the luxuriant vegetation of the Miocene period, even with- 
out any help from similar changes in the western hemi- 
sphere. 

Condition of North Ameria 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 River, the 
Parry Islands, and Greenland, indicate partial submergence 


1 In his recently published Lectures on Physical 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 very 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 Miocene times would have been 
fully equal to the Gulf Stream in heating power, while, owing to its being 
so much more concentrated, a large proportion of its heat may have 
reached the polar area. But the Arctic Ocean occupies less than one-tenth 
of the area of the tropical seas ; so that, whatever proportion of the heat 
of the tropical zone was conveyed to it, would, by being concentrated into 
one-tenth of the surface, produce an enormously increased effect. Taking 
this into consideration, we can hardly doubt that the opening of a sufficient 
passage from the Indian Ocean to the Arctic seas would produce the effects 
above indicated. 


ce alin lam ceil aaa 


CHAP, IX MILD ARCTIC CLIMATES 195 
of all these lands with the possible influx of warm water 
from the Pacific; and the considerable elevation of some 
of the Miocene beds in Greenland and Spitzbergen renders 
it probable 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 produced 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 the 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 Clumate of the Arctic Regrons. 
—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 water 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 have 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 Jand-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 complete interchange of the productions of the two 
continents! We may therefore admit that the communi- 

1 For an account of the resemblances and differences of the mammalia 


C.2 


196 ISLAND LIFE PART I 


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 disproportion between the extent of the polar 
and tropical seas is so enormous that a single wide opening, 
with an adequate impulse to carry in a considerable stream 
of warm water, would be amply sufficient for the complete 
abolition of polar snow and ice, when aided by the absence 
of any great areas of high land within the polar circle, such 
high land being, as we have seen, essential to the production 
of perpetual snow even at the present time. 

Those who wish 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- 
peratures of the opposite coasts of Europe and America is 
well known and has been already quoted, but the difference 
of their mean winter temperature is still more striking, and 
it is this which concerns us as more especially affecting the 
distribution of vegetable and animal life. Our mean 
winter temperature in the west of England is the same as 
that of the Southern United States, as well as that of 
Shanghai in China, both about twenty degrees of latitude 
further south ; and as we go northward 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 capable of 
supporting most of the vegetable products of the American 
coast in the latitude of Bordeaux. 


of the two continents during the Tertiary epoch, see my Geographical 
Distribution of Animals, Vol. I. pp. 140-156. 

1 Professor Haughton has made an elaborate calculation of the differ- 
ence between existing climates and those of Miocene times, for all the 
places where a Miocene flora has been discovered, by means of the actual 
range of corresponding species and genera of plants. Although this 
method is open to the objection that the ranges of plants and animals are 
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 CLIMATES 197 


With these astounding facts before us, due wholly to the 
transference of a portion of the warm currents of the 
Atlantic to the shores of Europe, even with all the disad- 
vantages of an icy sea to the north-east and ice-covered 
Greenland to 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 widely 
over the North Atlantic and thus losing the 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 znto the northern and Arctic seas. The heat 
that they gave out during the passage, instead of being 
widely dispersed by winds and much of it lost in the higher 
atmosphere, would directly ameliorate the climate of the 
continents they passed through, and prevent all 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 Physical Geography 


(p. 844) :— 
. Present Mi ; 

Latitude eeheeerediate: haute: Difference. 
1. Switzerland . . 47°.00 50 .6-1. 69°.8 F. 16°.2 ¥. 
Bepanizig . . , 54°21 ay oe 62. iG’. 
meeeeand ... . 65°. 30 a0 05 48°.2 ,, 12,6 5; 
4. Mackenzie River 65°.00 Li ght Sa 48°.2 ,, 28".8s; 
.| 5. Disco (Greenland)| 70°.00 19° G~,, BOO. z4 re Mee 
6. Spitzbergen . . 78°.00 Toys a gee ae eee, De 
7. Grinnell Land . 81°.44 | ey Sao See a4” 


It is interesting to note that Iceland, which is now exposed to the full 
influence of the Gulf Stream, was only 12°°6 F. warmer in Miocene times, 
while Mackenzie River, now totally removed from its influence was 
28° warmer. This, as well as the greater increase of temperature as we 
go northward and the polar area becomes more limited, is quite in accord- 
ance with the view of the causes which brought about the Miocene climate 
which is here advocated. 


198 ISLAND LIFE PART I 


Carolina, which by the Gulf Stream is transferred 20° 
northwards to our islands, might certainly, under the 
favourable conditions which prevailed during the Creta- 
ceous, Hocene, 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.! 

Liffect of High Hxcentricity 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 no 
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 

1 The objection has been made, that the long polar night would of itself 
be fatal to the existence of such a luxuriant vegetation as we know to have 
existed as faras 80° N. 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. Not only are numbers of Alpine and Arctic evergreens deeply 
buried in the snow for many months without injury, but a variety of 
tropical and sub-tropical plants are preserved in the hot-houses of St. 
Petersburg and other northern cities, which are closely matted during 
winter, and are thus exposed to as much darkness as the night of the 
Arctic regions. We have besides no proof that any of the Arctic trees or 
large shrubs were evergreens, and the darkness would certainly not be 
prejudical to deciduous plants. With a suitable temperature 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. 3 


, an 


CHAP. IX 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 the 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 would 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 ag to give the pole at midsummer actually 
more heat during the twenty-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 would 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 west of Scotland. 

But though high excentricity would not directly modify 
the mild climates produced by the state of the northern 
hemisphere which prevailed during Cretaceous, Kocene, 
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 we have seen that during the last three million years 
the excentricity has been almost always much higher than 


2.00 ISLAND LIFE PART I 


it is now, we should expect that the quantity of ice in the 
southern hemisphere will usually have been greater, and 
will thus have tended to increase the force of those oceanic 
currents which produce the mild climates of the northern 
hemisphere. 

Evidences of Climate in the Secondary and Paleozoic 
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 poorer, and 
there 1s 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 
abundant 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 le 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 


. 
4 
7 
— 
a 
} 
, 
‘ 


c ie: ale a iat a d= bo he = a 


CHAP. Ix GEOLOGICAL CLIMATES 201 


a blocks of Silurian and Old Red sandstone rocks which 
_ Professor Hull believes could only have been carried by 


floating ice. Similar breccias occur in the south of Scotland, 
and these are stated to be “overlain by a deposit of glacial 
age, so similar to the breccia below as to be with difficulty 
distinguished from it.” ? 

These numerous physical indications of ice-action over 
a considerable area during the same geological period, 
coinciding with just such a poverty of organic remains as 
might be produced by a very cold climate, are very 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 part 
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 however so satisfactory as 
those of Permian age, where we have the very kind of 
evidence we looked for in vain throughout the whole 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 Palzeozoic 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 frequent recur- 
rence of periods of high excentricity. - 

Warm Arctic Climates in Early Secondary and Paleozore 
Tvmes.—The evidence we have already adduced of the mild 
climates prevailing in the Arctic regions throughout the 
Miocene, Eocene, and Cretaceous periods is supplemented 
by a considerable body of facts relating to still earlier 
epochs. 

1 Geological Magazine, 1873, p. 320, 


202 ISLAND LIFE PART? 


In the Jurassic period, for example, we have proofs of a 
mild Arctic climate, in the abundant plant-remains of 
Kast 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, 
among which we may especially mention the numerous 
ammonites and the vertebre of huge reptiles of the 
genera 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 
widely 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 1s 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 1s 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 1s now 
or lower, for that would imply that the duration of cold 
conditions was greater than that of warm. Why then 
should the fauna and flora of the cold epochs never be 


CHAP. IX GEOLOGICAL CLIMATES 203 


preserved ? Mollusca and many other forms of life are 


abundant in the Arctic seas, and there is often a luxuriant 


dwarf woody vegetation on the land, yet in no one case has 
a single example of such a fauna or flora been discovered 
of a date anterior to the last glacial epoch. And _ this 


argument is very much strengthened when we remember 


that an exactly analogous series of facts is found over all 


the 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 anc plants, shows us that there 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 paleontological 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 was 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 PART I 


there is strong negative and some positive evidence of 
alternating warmer and colder conditions, not glacial, 
contained not only in English Kocene, 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 probably occurred at all geological epochs 
and their 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 Clumates as dependent on the 
Physical 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. Croll, 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 1s 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 1t mainly to 
the study of Dr. Croll’s writings, since my theory 1s 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. Croll I will now 
endeavour to summarise. 

Looking at the subject broadly, we see that the climatic 


1 Geological Magazine, 1877, p. 137. 


“OHAP. Ix GEOLOGICAL CLIMATES 205 


4 condition of the northern hemisphere is the result of the 


peculiar distribution of land and water upon the globe; 
and the general permanence of the position of the con- 
tinental and oceanic areas—which we have shown to be 
proved by so many distinct lines of evidence—is also im- 
plied by the general stability of climate throughout long 
geological periods. The land surface of our earth appears 
to have always consisted of three great masses in the 
north temperate zone, narrowing southward, and 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; leaving 


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 polar 
area, 

This arrangement is such as would cause the northern 
hemisphere to be always (as it is now) warmer than the 


southern, and this would lead to the preponderance of 


northward winds and ocean currents, and would bring 
about the concentration of the latter in three great streams 
carrying warmth to the north-polar regions, These streams 
would, as Dr. Croll has so well shown, be greatly increased 
in power by the glaciation of the south polar land ; and 
whenever any considerable portion of this land was ele- 
vated, such a condition of glaciation would certainly be 
brought about, and would be heightened whenever a high 
degree of excentricity prevailed. 

It is now the general opinion of geologists that the 
great continents have 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 
exposition of his views from 1856, when he discussed 
the subject in the American Journal, to the later editions 
of his Manual of Geology in which the same views are ex- 
tended to all the great continents. He says :— 

“The North American continent, which since early 


206 ISLAND LIFE PART I 


time had been gradually expanding in each direction from 
the northern Azoic, eastward, westward, and southward, 
and which, after the Palzozoic, was 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 
Kuropean 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 contents 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 explain the persistence, with slight fluctua- 
tions, of warm climates far mto the north-polar area 
throughout Palzeozoic, 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 


1 Manual of Geology, 2nd Ed. p. 525. See also letter in Nature, Vol. 
XXIII. p. 410. | . 


 OHAP. Ix GEOLOGICAL CLIMATES 207 


level caused by the earth’s centre of gravity being shifted 
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, Throughout earlier 
Tertiary and Secondary times an equally high excentricity 
often occurred, but it never produced a glacial epoch, be- 
cause the north temperate and polar areas had less high 
land, and were more freely open to the influx of warm 
oceanic currents. But wherever great plateaux with lofty 
mountains occurred in the temperate zone a considerable 
local glaciation 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 glaciation appears to have been 
more extensive, and it is quite possible that at this remote 
epoch a sufficient mass of high land existed in our area 
and northwards towards the pole, to have brought on a 
true glacial period comparable with that which has so 
recently passed away. 

Lstumate of the comparative effects of Geographical and 
Astronomical Causes in producing Changes of Clomate.—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 aphelion—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 avery 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 ISLAND LIFE PART I 


about the same time Scandinavia, the Alps, and the 
Pyrenees received a similar increase of altitude ; and that, 
almost simultaneously, 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 im 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 through- 
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. When, 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 


. 
3 


- omap. 1x GEOLOGICAL CLIMATES 209 


a 
preponderating influence, and without very large areas of 
high northern land to act as condensers, no perpetual snow 
is possible, and hence the initial process of glaciation does 
not occur. 

The theory as now set forth should commend itself to 
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 which 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 important departure from the great lines of 


elevation and depression originally marked out on the 
earth’s surface has ever taken place. 

Tt also shows us how important an agent in the pro- 
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 easily 
have led to half the land surface becoming covered with’ 
perpetual snow and ice, or being exposed to extremes of 
summer heat and winter cold, of which our water- 
permeated globe at present affords no example. We thus 


see that- what are usually regarded as geographical 


anomalies—the disproportion of land and water, the 
gathering of the land mainly into one hemisphere, and the 
singular arrangement of the land in three great 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 surface for 


human habitation is directly due. 


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 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 organic changes 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 expounded by Mr. Darwin, the 
variation and modification of organic forms is also a very 
slow process, and has usually been considered to require an 


:, 
a 
“ os 


CHAP. X THE EARTH’S AGE 211 


even longer series of ages than might satisfy the require- 
ments 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 period 
—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 the 
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 1s 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 during 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 Palzozoic period. Thus, from the fact that almost 
the whole of the Tertiary period has been required to convert 
the ancestral Orohippus into the true horse, 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- 


1 Nature, Vol. XVIII. (July, 1878), p. 268. ; 
P 


212 ISLAND LIFE - PARTI 


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 Paleozoic 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 Palaeozoic times we must go before 
we can hope to arrive at that common stock from which 
the crocodiles, lizards, Ornithoscelida, and Plesiosauria, 
which 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 whole series of geological 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 varied life we find no evidence of its 
having lived near the beginning of the zoological series. 
In a broad sense, compared with what must have gone 
before, both biologically and physically, all the phenomena 
connected with this old period seem, to my mind, to be of 
quite a recent description; and the climates of seas and 
lands were of the very same kind as those the world enjoys 
at the present day.” + 

These opinions, and the facts on which they are founded, 
are so weighty, that we can hardly doubt that, if the time 
since the Cambrian epoch is correctly estimated at 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 


1 “On the Comparative Value of certain Geological Ages considered as 
items of Geological Time.” (Proceedings of the Royal Society, 1874, p. 
334. ) . 


CHAP. X THE EARTH’S AGE 213 


—___— 


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 such periods as are 
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, 
Lord Kelvin has concluded 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. Croll 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 Deposition 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 
wear 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 
débris 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. Itis 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, smce the matter which 
causes this discolouration must be derived from the surface 


1 Trans. Royal Society of Edinburgh, Vol. XXIII. p. 161. Quarterly 
Journal of Science, 1877. (Croll on the ‘‘ Probable Origin and Age of the 
Sun.’’) 


914 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 
subaérial 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 Jand-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 applied 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 greater 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 sufficient number of points in 
its channel and at different depths, and repeating this 
daily or at other short intervals throughout the year, it is 
easy to determine the quantity of solid matter held in 
suspension and solution ; and if corresponding observations 
determine the quantity of water that is discharged, the 
total amount of solid matter brought down annually may 
be calculated. But besides this, a considerable quantity 
of sand or even gravel is carried along the bottom or bed 
of 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 
1 Philosophical Magazine, April, 1853. 


= OHAP. x THE EARTH’S AGE 215 


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 Mississippi removes one foot in 6,000 years. - 


» Ganges e 3 2,058 ,, 
5, Hoang Ho ,, F PAGS <2 53 
oe) Rhone ”) 9 1,528 2) 
», Danube me S 6,846 __,, 
9 Po 9 re) 729 9 
9 Nith oe) ” 4,723 oe) 


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 plateaux 
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 are probably 
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 surface 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.1 The mean altitude of the several 


1 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 the 
rate of denudation in Europe, from an idea apparently of being on the 
**safe side,” and of not over-estimating the rate of change. But this 
appears to me a most unphilosophical mode of proceeding and unworthy 
of scientific inquiry. What should we think of astronomers if they 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 were 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 Jowest 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 
of man ; and now that a means has been found of measuring the rate of 


216 ISLAND LIFE PART I 


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. Atthe 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 somewhat 
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 thickness 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 will not be nearer the 
truth for Eur ope than taking one North American river as the standard. 

1 *On the Height of the Land and the Depth of the Ocean,” in the 
Scottish Geographical Magazine, 1888. 

2 These figures are merely used to give an idea of the rate 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 ground everywhere rendered flatter. 
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 
remained 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. 


OMAP. X THE EARTH’S AGE 217 


<aes 
= 


a How to Estimate the Thickness of the Sedimentary Rocks, 
—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 Upper and Lower 
_ Silurian, each characterized by a distinct set of fossil 
_ remains, and the Upper Silurian again consists of a large 
_ number of separate beds, such as the Wenlock Limestone, 
_ the Upper Llandovery Sandstone the Lower Llandovery 
Slates, &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 thick bed 
_ or series of beds often thins out in a given direction, and 
sometimes disappears altogether, so that two beds which 
__wererespectively above and beneath it may come into contact. 
_ Asan example of this thinning out, American geologists 
__adduce the Palzeozoic formations of the Appalachian Moun- 
tains, which have a total thickness of 42,000 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 Yorkshire 
and Lancashire, but they thin out southwards, so that 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 upon the 
_ surface of a country so as to produce great irregularities of 
_ contour), but is a regular attenuation of the layers of rock, 
_ due to a deficiency of sediment in certain directions at the 
original formation of the deposit. Owing to this thinning 
_ out of stratified rocks, they are on the whole of far less 
_ extent than is usually supposed. When we see a geologi- 
cal map showing successive formations following each 
_ other in long irregular belts across the country (as is well 


218 ISLAND LIFE PART I 


_ $$$ ee al 


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 everywhere find all the others in 
succession lke 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, 
we 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 following statement of the depths at which the Paleozoic forma- 
tions have been reached in various localities in and round London was 
given by Mr. H. B. Woodward in his address to the Norwich Geological 
Society in 1879 :— 


Deep Wells through the Tertiary and Cretaceous Formations, 


SPST WIG fiche. Fic cusneaen at 1,022 feet reached Carboniferous Rock. 

Kentish Town ......... ree Uy | ape ,, Old Red Sandstone. 

Tottenham Court Road,, 1,064 _,, ,, Devonian. 

Black walt. sh soyscte net ee ,, Devonian or Old Red Sandstone, 
NMANG i iV oy sik clones eck SP BOD is »» Silurian (Wenlock Shale). 


We thus find that over a wide area, extending from London to Ware and 
Harwich, the whole of the formations from the Oolite to the Permian are 
wanting, the Cretaceous resting on the Carboniferous or older Paleozoic 
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. 


OHAP. X THE EARTH’S AGE 219 


es ees 


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 fact was 
demonstrated by the specimens of sea-bottom examined 
during the voyage of the Challenger, 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 purely organic, being formed of the calcareous or 
siliceous skeletons of globigerine, radiolarians, and 
diatomacez, or are clays formed of undissolved portions of 
these, together with the disintegrated or dissolved 
materials of pumice and volcanic dust, which being very 
light are carried by wind or by water over the widest 
oceans. 

From the preceding considerations we shall be better 
able to appreciate the calculations as to the thickness of 
stratified deposits made by geologists. Professor Ramsay 


has calculated that the sedimentary rocks of Britain alone 


\ gee SB) 7 


have a total maximum thickness of 72,600 feet; while 
Professor Haughton, from a survey of the whole world, 
estimates the maximum thickness of the known stratified 
rocks at 177,200 feet. Now these maximum thicknesses of 
each deposit will have been produced only where the con- 
ditions were exceptionally favourable, either in deep water 
near the mouths of great rivers, or in inland seas, or in 
places to which the drainage of extensive countries was 
conveyed by ocean currents; and this great thickness will 
necessarily be accompanied by a corresponding 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 representa- 
tion of their maximum thickness, though it undoubtedly is 
of their extent and bulk. When we see in how many 
distinct localities patches of the same formation occur, it 
seems improbable that the whole of the deposits formed 
during any one period should have been destroyed, even in 
such an area as Europe, while it is still more improbable 
that they should be so destroyed over the whole world ; and 


22.0 ISLAND LIFE PART I 
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 the 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 ; while, except in the rare case of 
an extensive formation being gute horizontal, and wholly 
exposed to the sea or to the atmosphere, denudation can 
have no tendency to diminish the thickness of any entire 
deposit.2, 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 mean 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 differ in lithological character or 
in organic remains. But we know that limestones, sand- 
stones, and shales, are always forming at the same time ; 


1 Geological Magazine, Vol. VIII., March, 1871. 

2 Mr. C. Lloyd Morgan has well illustrated this point by comparing the 
generally tilted-up strata denuded on their edges, to a library in which 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 place, which portion 
represents the thickness but not the size of the book. (Geological Magazine, 
1878, p. 161.) 


CHAP. X THE EARTH'S AGE 221 


while a great difference in organic remains may arise from 
comparatively slight changes of geographical features, or 
from difference in the depth or purity of the water in which 
the animals lived. 

How to Lstvmate the Average Rate of Deposition of the 
Sedimentary ocks—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 maximum 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 the 
matter brought down from the land will be deposited com- 
paratively close to the shore; that is, within twenty or 
thirty miles. If we suppose the portion deposited beyond 
thirty miles to be added to the deposits within that 
distance, and the whole reduced to a uniform thickness in 
a direction at right angles to the coast, we should probably 
include all areas where deposits of the maximum thickness 


1 Professor J. Young thinks it highly probable that—‘‘ the Lower Green- 
sand is contemporaneous with part of the Chalk, so were parts of the 
Wealden ; nay, even of the Purbeck a portion must have been forming 
while the Cretaceous sea was 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. C. British 
- Association, 1876. ) 

2 Mr. (now Sir) John Murray in his more careful estimate makes it 

about 514 millions. 


222 ISLAND LIFE PART I 


are forming at the present time, along with a large but 
unknown proportion of surface where the deposits 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, we 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 thickness as measured by geologists, we shall 
certainly over rather than under-estimate the possible rate 
of deposit. 

Now 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 


1 As by far the larger portion of the denuded matter of the globe passes . 
to the sea through comparatively few great rivers, the deposits must 
often be confined to very limited areas. Thus the denudation of the vast 
Mississippi basin must be almost all deposited in a limited portion of the 
Gulf of Mexico, that of the Nile within a small area of the Eastern 
Mediterranean, and that of the great rivers of China—the 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 than that of maximum deposit, which 
is the basis on which I have here made my estimates. In the case of the 
Mississippi, it is stated by Count Pourtales that along the plateau 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 Rhizopod shells alone, or these mixed with coral sand, 
Nullipores, and other calcareous organisms (Dana’s Manual of Geology, 
2nd Ed. p. 671). It is probable, therefore, that a large proportion of the 
entire mass of sediment brought down by the Mississippi is deposited on 
the limited area above indicated. 

Professor Dana further remarks: ‘‘ Over interior oceanic basins as well 
as off a coast in quiet depths, fifteen or twenty fathoms and beyond, the 
deposits are mostly of fine silt, fitted for making fine argillaceous rocks, 
as shales or slates. When, however, the depth of the ocean falls off 
below a hundred fathoms, the deposition of silt in our existing oceans 
mostly ceases, unless in the case of a great bank along the border of a 
continent.” 


ee THE EARTH'S AGE 993 


miles is deposited. As these two areas are as 1 to 19, it 
follows that deposition, as measured by maximum thickness, 
goes on at least nineteen times as fast as denudation— 
probably very much faster. But the mean rate of denuda- 
tion over the whole earth 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 maximum 
thickness of all the stratified rocks of the globe is, according 
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 fate of Geological Change Probably Greater in very 
Remote Times.—The opinion that denudation and deposition 
went on more rapidly in earlier times owing to the 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 whole 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 Haughton 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 whole sea-bottom instead of over a narrow belt near the 
coasts, a supposition entirely opposed to all the known facts, and which 
had been shown by Dr. Croll, five years previously, to be altogether erro- 
neous. (See Nature, Vol. XVIII., p. 268, where Professor Haughton’s 
paper is given as read before the Royal Society. ) 

2 See Geological Magazine for 1877, p. 1. 


a eee es see 


— ss 


224 ISLAND LIFE - PARTI 


—_——- 


and more powerful oceanic currents, all producmg 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 appears that, as we go back into the past, 
all the forces tending to the contmued 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 produce 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 Preceding Estimate of Geological Time. ik 
is not of course supposed that the calculation here given 


CHAP. X THE EARTH’S AGE 995 


makes any approach to accuracy, but it is believed that it 
does indicate the order of magnitude of the time required. 
We have a certain number of data, which are not guessed 
but the result of actual measurement; such are, the amount 
of solid matter carried down 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-aérial 
_ denudation, but it is now believed to be comparatively 
slow in its action.2, Whatever it may be, however, it adds 
to the rate of formation of new strata, and its omission 
from the calculation 1s 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. 


1 Tn his reply to Sir W. Thomson, Professor Huxley asswmcd one foot 
in 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 deposition is many times smaller than the area 
of denudation. 

2 Dr. Croll and Sir Archibald Geikie have shown that marine denudation 
is very small in amount as compared with sub-aérial, since it acts only locally 
on the edge of the land, whereas the latter acts over every foot of the 
surface. Mr. W. T. Blanford argues that the difference is still greater in 
tropical than in temperate latitudes, and arrives at the conclusion that— 
‘“‘Tf 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). Now, as our estimate of 
the rate of sub-aérial denudation cannot pretend to any precise accuracy, 
we are justified in neglecting marine denudation altogether, especially as 
we have no method of estimating it for the whole earth with any approach 
to correctness. 


————-.) ae ST 


4 
a 
a 


Q 


226 ISLAND LIFE PART I 


—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 place in nature, and 
- there is then no inherent tendency to change. But almost 
any change whatever in the external world disturbs this 
equilibrium, and may set in motion a whole series of 
organic revolutions before it is restored. A change of 
climate in any direction will be sure to injure some and 
benefit other species. The one will consequently diminish, 
the other increase in number ; and the former may even 
become extinct. But the extinction of a species will 
certainly affect other species which it either preyed upon, 
or competed with, or served for food ; while the increase 
of any one animal may soon lead to the 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 ina wild state ; and 
Azara and Rengger have shown that 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 are, must be 


CHAP. X THE RATE 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 which, after many fluc- 
tuations, would certainly result in the extinction of some 
species, the modification of others, and a considerable 
alteration in the proportionate numbers and the geograph- 
ical distribution of almost all. 

Any other changes which led to the intermingling of 
species whose ranges were usually separate would produce 
corresponding results. Thus, increased severity of winter 
or summer temperature, causing southward migrations and 
the crowding together of the productions of distinct regions, 
must inevitably produce a struggle for existence, which 
would lead to many changes both in the characters and 


G2 


228 ISLAND LIFE PART [ 


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. 

Geographical Mutations as a Motwe Power in Bringing 
about Organic Changes.—Now, if we consider the various 
geographical changes which, as we have seen, there is 
good reason to believe have ever been going on in the 
world, we shall find that the motive power to initiate and 
urge on organic changes has never been wanting. In the 
first place, every continent, though permanent in a 
general sense, has been ‘ever subject to imnumerable 
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 
loct 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 separations of the land masses of 
the globe, joining together continents which were before 
divided, and breaking up others into great islands or 
extensive archipelagoes. Such alterations of the means 
of transit would probably affect the organic world even 
more profoundly than the changes of area, of altitude, or 


CHAP. X THE RATE OF ORGANIC CHANGE 229 


of climate, since they afforded the means, at long intervals, 
of bringing the most diverse forms ‘nto competition, and 
of spreading all the great animal and vegetable types 
widely over the globe. But the isolation of considerable 
masses of land for long periods also afforded the means 
of preservation to many of the lower types, which thus 
had time to become modified into a variety of distinct 
forms, some of which became so well adapted to special 
modes of life that they have continued to exist to the 
present day, thus affording us examples of the life of early 
ages which would probably long since have 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 generally nocturnal or 
subterranean in their habits; and the Lemurs, which are 
most abundant in Madagascar, where they have long been 
isolated, and almost removed from the competition of 
higher forms. 

Climatal Revolutions as an Agent in Producing Organic 
Changes—The geographical and geological changes we 
have been considering are probably those which have been 
most effective in bringing about the great 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 must 
impute some of the more remarkable changes both in the 
specific characters and in the distribution of organisms.! 

1 Agassiz appears to have been the first to suggest that the principal 


230 . ISLAND LIFE - PARTI 


Although the geological evidence is opposed to the belief 
in early glacial epochs except at very remote and distant 
intervals, there 1s 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 perihelion, 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 hemisphere would then have a 
very different climate than when the changing phase of 
precession brought a very cool summer and a very mild 
winter—a 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, without any such decided change of type either 
in the vegetation or the animals that we could say from 
their fossil remains that any change of climate had taken 
place. Let us suppose, for instance, that the climate of 
England and that ‘of Canada were to be mutually ex- 
changed, and that the change took five or six thousand 
years to bring about, it cannot be doubted that consider- 
able modifications in the fauna and flora of both countries 
would be the result, although it is impossible to predict 
epochs 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. 


CHAP. X THE RATE OF ORGANIC CHANGE 231 


what the precise changes would be. We can safely say, 
however, that some species would stand the change better 
than others, while it is highly probable that some would be 
actually benefited by it,and that others would 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 when there 
was a high excentricity, for it is impossible to doubt that 
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 98, 
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 condi- 
tions so as to produce climatic alterations in different 
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 PART I 


excentricity and consequent slight inequality of sun- 
heat. 

Present Condition of the Earth One of Exceptional Stability 
as Regards Climate.—It will be seen, by a reference to the 
diagram at page 171, that during the last three million 
years the excentricity has been /ess 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 shght changes 
that did occur would probably be so slow and so little 
marked that the various species would be able to adapt 
themselves to them without much disturbance; and 
the result would be an epoch of exceptional stability of 
species. | 

But it is from this very period of exceptional stability 
that we obtain our only scale for measuring the rate of 
organic change. It includes not only the historical period, 


cHar.x MEASUREMENT OF GEOLOGICAL TIME 233 


but that of the Swiss Lake. dwellings, the Danish shell- 

mounds, our peat-bogs, our sunken forests, and many of our 

superficial alluvial deposits—the whole in fact, of the iron, 

bronze, and neolithic ages. Even some portion of the 
-palzolithic age, and of the more recent gravels and cave- 
earths may come into the same general period if they 
were formed when the glacial epoch was passing away. 
Now throughout all these ages we find no indication of 
change of species, and but little, comparatively, of migra- 
tion. We thus get an erroneous idea of the permanence 
and stability of specific forms, due to the period immediately 
antecedent to our own being a period of exceptional per- 
manence and stability as regards climatic and geographical 
conditions.! 

Date of Last Glacial Hpoch and tts Bearing on the 
Measurement of Geological Time—Directly we go back 
from this stable period we come upon changes both in the 
forms and in the distribution of species; and when 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 regions. 
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.2 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 


1 This view was, I believe, first put forth by myself in a paper read 
before the Geological Section of the British Association in 1869, and 
subsequently in an article in Nature, Vol. I. p. 454. It was also stated 
by Mr. S. B. K. Skertchley in his Physical System of the Universe, p. 363 
(1878) ; but we both founded it on what I now consider the erroneous 
doctrine that actual glacial epochs recurred each 10,500 years during 
periods of high excentricity. 

2 Explication d’une seconde édition de la Carte Géologiquc de la Terre 
(1875), p. 64. 


234 ISLAND LIFE PART I 


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, we 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, 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 mitiation, and the most powerful of 
such conditions is a great extent of high land. Now we 
know that the Alps acquired a considerable part of their 
elevation during the latter part of the Miocene period, 
since Miocene rocks occur at an elevation of over 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 earlier 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 TIME 235 


fuchsias and tree-ferns on the very borders of huge 
glaciers, descending to within 700 feet of the sea-level. 
It is not pretended that these estimates of geological time 
have any more value than probable guesses; but it is 
certainly a curious coincidence that two remarkable 
periods of high excentricity should have occurred, at such 
periods and at such intervals apart, as very well accord 
with the comparative remoteness of the two deposits in 
which 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 Principles 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 the 
whole Tertiary epoch, and the latter at one-fourth that of 
geological time since the Cambrian period. Professor 
Dana, on the other hand, estimates the Tertiary as only 
one-fifteenth of the Mesozoic and Palzeozoiccombined. 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 when 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, which 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 PART I 


far more extensive period which includes all possibility of 
life upon the earth. 

Concluding Remarks.—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 geologists, 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 produced 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 


EF _ ase OF GEOLOGICAL TIME 237 


face of the earth. These studies will, it is believed, 
us in a condition to solve most of the problems 
ted by the distribution of animals and plants, when- 
the necessary facts, both as to their distribution and 
affinities, are sufficiently well known; and we now 
roceed to apply the principles we have established to the 
‘erpretation of the phenomena presented by some of the 
e important and best known of the islands of our globe, 
ting ourselves to these for reasons which have been 
ady sufficiently explained in our preface. 


—- PART I 


= 7. a 


«INSULAR FAUNAS AND FLORAS 


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, forming the first part of our 
work, we have discussed, more or less fully, the general 
features presented by animal distribution, as well as the 
various physical and biological changes which have been 
the most important agents in bringing about the present 
condition of the organic world. 

We now proceed to apply these principles to the solution 
of the numerous problems presented by the distribution 
of animals; and in order to limit the field of our inquiry, 
and at the same time to deal only with such facts as may 
be rendered intelligible and interesting to those readers 
who have not much acquaintance with the details of 
natural history, we propose to consider only such phenom- 
ena as are presented by the islands of the globe. 

Importance of Islands in the Study of the Distribution of 
Organisms.—Islands possess many advantages for the study 
of the laws and phenomena of distribution. As compared 
with continents they have a restricted area and definite 
boundaries, and in most cases their geographical and 
biological limits coincide. ‘The number of species and of 
genera they contain is always much smaller than in the 


R 


242 ISLAND LIFE PART II 


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 with 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. XI THE CLASSIFICATION OF ISLANDS 243 


part of a continent. This was quite opposed to the 
opinions of the scientific men of the day, who almost 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 fair 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 thought 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 other- 

R 2 


244 ISLAND 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 periad. 

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, some of the most characteristic continental 
orders or families being quite unrepresented, while a few 
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 characters 
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. 

Oceanie Islands.—The total absence of warm-blooded 
terrestrial animals in an island otherwise well suited to 
maintain them, is held to prove that such island is no mere 
fragment of any existing or submerged continent, but one 
that 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. XI OCEANIC ISLANDS. 245 


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 crossing 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 AZORES, OR WESTERN 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 the Azorean Fauna 
and Flora. 


BERMUDA 


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 Mollusca—Flora of 
Bermuda—Conceluding 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 we shall have to deal 
with further on. The Azores and Bermuda offer great 
contrasts in physical features, but striking similarities in 
geographical position. The one is volcanic, the other 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. XII 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 39° 40’ N. Lat. and 
stretching in a‘south-east and north-west direction 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 Kurope, being rather under 900 miles from the 
coast of Portugal, from which it is separated by an ocean 
_ 2,500 fathoms deep. 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 3()0 miles in all directions. 
_ These great depths 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 part 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 fact may be of im- 
portance in considering the origin and peculiar features of 
the fauna and flora. It thus appears that in all physical 
features the Azores correspond strictly with our physical 
definition of “oceanic islands,” while their great distance 


248 ISLAND LIFE PART 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. 


Nore.—The light tint shows where the sea is less than 1,000 fathoms deep. 
The dark tint ,, 3 fg more than 1,000 fathoms deep. 
The figures show depths in fathoms. 


Chief Zoological Features of the Azoresi—The great 
feature of oceanic islands—the absence of all indigenous 
land-mammalia and amphibia—is well shown in this 


1 For most of the facts as to the zoology and botany of these islands, I 
am indebted to Mr. Godman’s valuable work—WNatural History of the 
Azores or Western Islands, by Frederick Du Cane Godman, F.L.S., F.Z.S., 
&c., London, 1870. 


CHAP. XIT THE AZORES 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 are 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 European 
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-water fish which is truly indigenous to the islands. 
When we consider that the nearest part of the group 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.—F ifty-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 
Kuropean 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 bie at (Buteo vulgaris) 

2. Long-eared Owl ay a (Asto otus) 

3 Barn Owl ee a (Strix flammea) 

4, Blackbird id eee (Turdus merula) 

5. Robin Se fe (Erythacus rubecula) 
6. Blackcap 2 = (Sylvia atricapilla) 


250 ISLAND LIFE PART II 

7. Gold-crest (Regulus cristatus) 

8. Wheatear (Saxicola ceenanthe) 

9. Grey Wagtail (Motacilla sulphurea) 
10. Atlantic Chaffinch (Fringilla tintillon) 
11. Azorean Bullfinch (Pyrrhula murina) 
12. Canary (Serinus canarius) 
13. Common Starling (Sturnus vulgaris) 
14. Lesser Spotted Woodpecker (Dryobates minor) 

15. Wood-pigeon (Columba palumbus) 
16. Rock Dove (Columba livia) 


ive 
18. 


Red-legged Partridge 
Common Quail 


(Caccabis rufa) 
(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 Azorcan Bird-fauna.—The questions we 
have now before us are—how did these eighteen species of 
birds first reach the Azores, and how are we to explain the 
presence of a single peculiar species while all the rest are 
identical with 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 mentioned 
by Mr. Godman show that this is the case. A barn-owl, 
much exhausted, flew on board a whaling-ship when 500 
miles §.W. of the Azores; and even if it had come from 


CHAP. XII THE AZORES 251 


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 which is almost conclusive in favour of the 
bird-population having arrived as stragglers is, that they 
are most abundant in the islands nearest to Kurope and 
Africa. The Azores consist of three divisions—an eastern, 
consisting of tivo islands, St. Michael’s and St. Mary’s; a 
central of five, Terceira, Graciosa, St. George’s, Pico, and 
Fayal; and a western of two, Flores and Corvo. Now had 
the whole group 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 the 
greatest number and variety of birds. But the fact that 
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 including 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 (which, however, does not differ from the 
common European bullfinch more than do some of the 
varieties of North American birds from their type-species) 
is not difficult; the wonder rather being that there are 
not more peculiar forms. In our third chapter we have 
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 hardly have a greater difference of conditions 


252 ISLAND LIFE PART II 


than between the continent 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 differences 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 


SS Pr 


CHAP. XII THE AZORES 253 


birds accounts in a great measure for their identity with 
those of Europe, because, whatever change has occurred 
must have been effected in the islands themselves, and in 
a time limited to that which has elapsed since the glacial 
epoch passed away. 

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 
Kurope, 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 :— 


CARABIDA. 


Anchomenus aptinoides ...Allied to a species from the Canaries. 
Bembidium hesperus ...... Allied to the European B. loetwim. 


DYTISCIDZ. 


Agabus godmanni ......... Allied to the European A. dispar. 


COLYDIIDZ. 


Tarphius wollastoni ...... A genus almost peculiar to the Atlantic islands. 


QK4 ISLAND LIFE PART It 


ELATERIDS. 

Heteroderes azoricus......... Allied to a Brazilian species. 

Elastrus dolosus ..........4. Belongs to a peculiar Madagascar genus! 
MELYRID&. 

Altalus miniaticollis ...... Allied to a Canarian species. 
RHYNCOPHORA. 

Phieophagus variabilis ...Allied to European and Atlantic species. 

Act lles AP OUCH... cc ccaevase A Mediterranean end Atlantic genus. 

Laparocerus azoricus ...... Allied to Madeiran species. 


Asynonychun godmansi ...A peculiar genus, allied to Brachyderes, of the 
south of Europe. 
Neocnemis occidentalis ...A peculiar genus, allied to the Kuropean genus 
Strophosomus. 
HETEROMERA. 


TLCLOOS GZOTIOUS eS edan nes Allied to H. vulcanus of Madeira. 


STAPHYLINIDZ. 
Xenomma melanocephala..Allied 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 
ege or larva state or even as perfect insects, they may be 
drifted safely for weeks over the ocean, buried in the light 
stems of plants 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 lability to be destroyed by insectivorous birds, 
we shall see that, although there may be a greater proba- 
bility of insects asa whole reaching the islands, the chance 
against any particular species arriving there, or against the 
same species arriving frequently, 1s 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 what 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 which are 
pre-eminently wood, root, or seed eaters, are those which 
present the greatest amount of speciality. The two 
Elateridz alone exhibit remote affinities, the one with a 
Brazilian the other with a Madagascar group; while the 
only peculiar genera belong to the Rhyncophora, 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-glacial 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 (Hlastrus 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 Mada- 
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. 
Madagascar, in fact, has insect relations with every part of 


256 ISLAND LIFE PART II 


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 
widely 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 Kurope or the other Atlantic 
islands, while thirty-two are peculiar, though almost all 
are distinctly allied to European types. The majority of 
these shells, especially the peculiar forms, are very small, 
and many of them may date back to beyond the glacial 
epoch. The eggs of these would be 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, probably, 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 Chap. V. p. 78. 


; 
Ds 
‘ 


——-— 


CHAP. XII THE AZORES: 257 


— ae ae OT 


_ 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 the 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 of service 
in our discussion of more difficult and more complex 
problems. 

There are in the Azores 480 known species of flowering- 
plants and ferns, of which no less than 442 are found also 
in Europe, Madeira, or the Canary Islands; while thirty- 
eight are peculiar to the Azorcs, but are more or less closely 
allied to European species. As botanists are no less prone 
than zoologists to invoke former land-connections and 


continental extensions to account for the wide dispersal of 


objects of their study, it will be well to examine somewhat 
closely what these facts really imply. 

The Dispersal 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 ex- 
ceptionally 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 fit 
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 are 
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, 

S 


258 ISLAND LIFE PART IT 


_—_—_— ee eee 


Beta, oats, Capsicum, and the potato, grew after 100 days’ 
immersion, while 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 which cross the Indian ocean from 
the Seychelle Islands to the coast of Sumatra, and the 
West Indian beans which frequently reach the west coast 
of Scotland. There is therefore ample evidence of the 
possibility of seeds being conveyed across the sea for great 
distances by winds and surface currents.! 

Birds as Seed-carriers.—The great variety of fruits that 
are eaten by birds afford a means of plant-dispersal in 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 the 
means of introducing many plants into the islands. 

Birds also frequently have small portions of earth on 
their feet; and Mr. Darwin has shown by actual experi- 
ment that almost all such earth contains seeds, Thus in 


1 Some of Mr. Darwin’s experiments are very interesting and suggestive. 
Ripe 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 of 
germination seem never to have been wholly destroyed. Now, as oceanic 
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! Buteven 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 asingle experiment with only ninety-four plants, must happen hundreds 
or thousands of times and with hundreds or thousands of species, naturally, 
and thus afford ample opportunities for successful migration. (See Origen 
of Specics, 6th Edition, p. 325.) 


Sa a i Se 


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 wounded 
red-legged partridge had a ball of earth weighing six and 
a half ounces adhering to its leg, and from this earth Mr. 
Darwin raised no less than eighty-two separate plants of 
about five distinct species. Still 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 of 
food, or come there to drink, it is evident that great 
numbers 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.? 


1 The following remarks, kindly communicated to me by Mr. H. N. 
Moseley, naturalist to the Challenger, throw much light on the agency of 
birds in the distribution of plants :—‘‘ Grisebach (Veg. der Erde, Vol. II. p. 
496) lays much stress on the wide ranging of the albatross (Diomedea) 
across the equator from Cape Horn to the Kurile Islands, and thinks that 
the presence of the same plants in Arctic and Antarctic regions may be 
accounted for, possibly, by this fact. I was much struck at Marion 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 mound 
of turf and herbage. Some of the indigenous plants, e.g. Acena, have 
flower-heads which stick like burrs to feathers, &c., 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 part in the distribution of plants, 
and especially account, in some measure, for the otherwise difficult fact 
(when occurring in the tropics), that widely distant islands have similar 
mountain plants. The Procellaria and Puffinus in nesting, burrow in the 
ground, as far as I have seen choosing often places where the vegetation 
is the thickest. The birds in burrowing get their feathers covered with 
vegetable mould, which must include spores; and often seeds. In high 
latitudes the birds often burrow near the sea-level, as at Tristan d’Acunha 
or Kerguelen’s Land, but in the tropics they choose the mountains for their 
nesting-place (Finsch and Hartlaub, Orn. der Viti-und Tonga-Inseln, 1867, 
Einleitung, p. xviii.). Thus, Pufinws megasi nests at the top of the Koro- 
basa basaga mountain, Viti Levu, fifty miles from the sea. A Procellaria 
breeds in like manner in the high mountains of Jamaica, I believe at 7,000 
feet. Peale describes the same habit of Procellaria rostrata at Tahiti, and 
I saw the burrows myself amidst a dense growth of fern, &c., a5 4,400 feet 
elevation in that island. Phaethon has a similar habit. It nests at the 


s'2 


260 ISLAND LIFE PART II 


Facilities for Dispersal of Azorean Plants—Now in the 
course of very long periods of time the various causes 
here enumerated would be sufficient to stock the remotest 
islands with vegetation, and a considerable part of the 
Azorean flora appears well adapted to be so conveyed. Of 
the 439 flowering-plants in Mr. Watson’s list, I find that 
about forty-five belong to 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 
tor 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 laurel, myrtle, laurestinus, elder, 
Laurus canariensis, Myrica faya, and a peculiar juniper— 
all small berry-bearers, and therefore likely to have 
been conveyed by one or other of the modes suggested 
above. 

There can be little doubt that the truly indigenous flora 
of the islands is far more scanty than the number of 
plants recorded would imply, because a large but unknown 
proportion of the species 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 attempted 
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 Kilauea, Hawaii, at 4,000 feet elevation, and also high up in Tahiti. 
In order to account for the transporation of the plants, it is not of course” 
necessary that the same species of Procellaria or Diomedea should now 
range between the distant points where the plants occur. The ancestor of 
the now differing species might have carried the seeds. The range of the 
genus is suflicient.”’ 


CHAP. XII THE AZORES 261 


there will still remain a wonderfully rich and varied flora 
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 here 
by no means reached the limit of distance to which plants 
can be conveyed by natural means across the ocean; and 
this conclusion will be of great value to us in investigating 
other cases where the evidence at our command is less com- 
plete,and theindications of origin more obscure or conflicting. 

Of the thirty-eight species! which are considered to be 
peculiar to the islands, all are allied to European plants 
except six, whose nearest affinities are in the Canaries or 
Madeira. The most distinct of all the Azorean plants is 
the Campanula vidalii, which is a shrubby species, with 
rosettes of leathery leaves at the ends of the branches, and 
rather large white flowers with an orange ring on the disc. 
Mr. Godman compares its general appearance with that of 
a shrubby Sempervivum. With these exceptions, most 
of the peculiar Azorean species are closely allied to 
Kuropean 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 Peculiarities of the Azor- 
eam Fauna and Flora.—There is one conclusion to be 
drawn from the almost wholly European character of the 
Azorean fauna and flora which deserves special attention, 
namely, that the peopling of remote islands is not due 
so much to ordinary or normal, as to extraordinary and 
exceptional causes. These islands lie in the course of the 


1 Mr. Watson considered the peculiar species to be forty, but they have 
been reduced to thirty-eight by Dr. Trelease in his recent work on 7'h¢ 
Botany of the Azores, 


262 ISLAND LIFE PART II 


——— ee 


south-westerly return trades and also of the Gulf Stream, 
and we should therefore naturally expect that American 
birds, insects, and plants would preponderate if they were 
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. 


The 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 Geographical Ds- 
tribution of Animals (Vol. I. pp. 208-215); while a special 
study of the beetles of Madeira as illustrating the origin 
and peculiarities of insular faunas, will be found in my 
Studics Scientific and Social, Vol. L., Chapter XII We 
will therefore pass on to other cases which have been less 
fully discussed elsewhere. | 


BERMUDA. 

The Bermudas are a small group of low islands formed 
of coral, and blown coral-sand consolidated into rock. 
They are situated in 32° N. Lat. about 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.1 Immediately beyond these reefs, how- 


1 Nature, Vol. VI. p. 262, ‘‘ Recent Observations in the Bermudas,” by 
Mr. J. Matthew Jones, 


CHAP. XII BERMUDA 263 


ever, extends a very deep ocean, while about 450 miles 
distant in a south-east direction, the deepest part of the 
North Atlantic is.reached, where soundings of 3,825 and 


MAP OF BERMUDA AND THE AMERICAN COAST. 


Note.—The light tint indicates sea less than 1,000 fathoms deep 
The dark tint a », more than 1,000 fathoms deep. 
The figures show the depth in fathoms. 


3,875 fathoms have been obtained. It is clear therefore 
that these islands are typically oceanic. 
Soundings were taken by the Challenger in four differ- 


264 ISLAND LIFE PART 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 
from 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 


TT 


<——55 MILES—< 18 MILES ><———-46 MILES.—_—_> 


\Y 


SECTION OF BERMUDA AND ADJACENT SEA-BOTTOM. 


The figures show the depth in fathoms at fifty-five miles north and forty-six miles south 
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 Paleozoic district. It has however 
long been known that these rocks are all due to the wind, 


CHAP. XII BERMUDA 265 


which blows up the fine calcareous sand, the product of the 
disintegration of coral, shells, serpule, and other organisms, 
. forming sand-hills forty and fifty feet high, which 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, filling every 
fissure with 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, both in colour 
and chemical composition, the red clay of the ocean floor, 
found widely spread in the Atlantic at depths of from 2,300 
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 high-water mark some distance into the sea, 
originally came from the ocean floor, and that when by 
volcanic agency the Bermuda column was raised from the 
depths of the sea, its summit, most probably broken in 
outline, appeared above the surface covered with this red 
mud, which in the course of ages has but slightly changed 
its composition, and yet possesses sufficient evidence to 
prove its identity with that now lymg contiguous to the 
base of the Bermuda column.” But in his Gude to 
Bermuda Mr, Jones tells us that this same red earth has 
been found, two feet thick, under coral rock at a depth of 
forty-two feet below low-water mark; and that it “rested 
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 different 
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.2. There is however 
one lizard, which Professor Cope considers to be distinct 
from any American species, and which he has named 
Plestiodon (Humeces) longirostris. It is said to be most 
nearly allied to Humeces quinquelineatus 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 1s 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. 

Lirds.—N otwithstanding its small size, low altitude and 


1 “The late Sir C. Wyville 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 Molluscs, [vide Voyage of the 
Challenger, Atlantic, Vol. 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 from the disintegration of pumice, which 
is continually found floating on the surface of the sea. [See Murray, ‘‘ On 
the Distribution of Voleanic Debris Over the Floor of the Ocean ;”’ Proce. 
Roy. Soc. Edin. Vol. 1X. 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 quantity 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 voleanic rock, which is believed to form the nucleus 
of the island.” The Voyage of H.M.S. Challenger, Narrative of the Cruise, 
Vol. I. 1885, pp. 141—142. 

2 Four bats occur rarely, two being N. American, and two West Indian 
Species. The Bermuda Islands, by Angelo Heilprin, Philadelphia. 
1889. 


CHAP, XII BERMUDA 267 


remote position, a great number of birds visit Bermuda 
annually, 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 would 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 
nearly 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. Galcoscoptes carolinensis. (The Cat bird.) Migvates along the east 
coast of the United States. 

2. Sialia sialis. (The Blue bird.) Migrates along the east coast. 

3. Vireo noveboracensis. (The White-eyed green Tit.) Migrates along 
the east coast. 

4, Passer domesticus. (The English Sparrow.) ? Introduced. 

5. Corvus americanus. (The American Crow.) Common over all 
North America. 

6. Cardinalis virginianus. (The Cardinal bird.) Migrates from 
Carolina southward. 

7. Chamepelia passerina, (The ground Dove.) Louisiana, W. Indies, 
and Mexico. 

8. Ortyx virginianus. (The American Quail.) New England to 
Florida. 

9. Ardea herodias. (The Great Blue Heron.) All North America. 

10. Gallinula galeata. (The Florida Gallinule.) Temperate and 


tropical North America. 
11. Phéeton flavirostris. (The Tropic Bird.) 


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 howéver long they 
may have inhabited the islands there has been no chance 
for them to have acquired any distinctive characters 
owing to the want of isolation. 

Among the most regular visitants which are not resident, 
are the common N. American kingfisher (Ceryle alcyon), 


268 ISLAND LIFE PART II 


the night-hawk (Chordeiles virginianus), the wood wagtail 
(Stwrus noveeboracensis), the snow-bunting (Plectrophanes 
nwalis), and the wide-ranging rice-bird (Dolichonyx 
oryzvvora), all very common and widespread in North 
America. 

Comparison of the Bird-faunas of Bermuda and the 
Azores—The bird-fauna of Bermuda thus differs from that 
of the Azores, in the muchsmaller 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, with 
a sunny climate, luxuriant vegetation, and abundant insect- 
life during 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 
with the hurricanes of the West Indies and the northerly 
gales of the ceast 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 
westerly gale, they are rapidly driven sea-ward. The great 
majority no doubt perish, but some reach the Bermudas 


ee ee AP 


. 
; 
b 
, 
- 
- 
& 


CHAP. XII BERMUDA 269 


and form one of its most striking autumnal features. In 
October, Mr. Jones tells us, the sportsman enjoys more 
shooting than at any other time. The violent revolving 
gales, which occur almost weekly, bring numbers of birds 
of many species from the American continent, the different 
members of the duck tribe forming no inconsiderable 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 migratorius), the yellow- 
rumped warbler (Dendreca coronata), the pine warbler 
(Dendraca pinus), the wood wagtail (Siwrus noveboracensis), 
the summer red bird (Pyranga cstiva), the snow-bunting 
(Plectrophanes nivalis), the red-poll (4giothus linarius), 
the king bird (Zyrannus carolinensis), and many others. 
It is no doubt in consequence of this repeated immigration 
that none of the Bermuda birds have acquired 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 (Saazcola enanthe), which visits Iceland and 
Lapland and sometimes the northern United States; the 
skylark (Alauda arvensis), but this was probably an im- 
ported bird or an escape from some ship; the land-rail 
(Crex pratensis), which also wanders to Greenland and the 
United States ; and the common snipe (Scolopax gallinago), 
which occurs not unfrequently in Greenland but has not 
yet been noticed in North America. It is however so like 
the American snipe (S. wilsonz), 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. 

Insects of Bermuda.—tInsects appear to be very scarce ; 
but it is evident from the lists given by Mr. Jones, and 
more recently by Professor Heilprin, that only the more 
conspicuous species have been yet collected. These com- 


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 competent entomological collector 
visits the islands it 1s impossible to say whether there are 
or are not any peculiar species. 

Land Mollusca.—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. E. R. Sykes, on the authority of the latest 
American writer, Pilsbry (7rans. Conn. Acad., Vol. X., 
Sept. 1900). 

It will be seen that the number of the species has been 
somewhat increased and that two species are now con- 
sidered to be peculiar which were not so ranked in the 
former list, the actual additions being three West Indian 
or North American species, and one East Indian almost 
certainly introduced. The species which are peculiar 
to the islands are indicated by italics, and the peculiar 
genus by small capitals. 


LIsT OF THE LAND SHELLS OF BERMUDA. 


1. Helix (Cochliella) ventricosa. (Drap.) European. Introduced. 

2. 4, (Vallonia) pulchella. (Miill.). a ts 

3. Eulota similaris (Miill.) ... ope | 

4, Thysanophora vortex. (Pfr.) ... West Indies. 

5. Microphysa hypolepta. (Shuttlw.)... Peculiar species. 

6. Polygyra microdonta. (Desh.) ... S. United States, Bahamas. 
i i, @ppressa.- (Say-.) ... ... Virginia, &c. % Introduced. 
8. Rumina decollata. (Linn.) ... 8. Europe. Introduced. 

9, Subulina octona. (Ch Vives . W. Indies. Introduced. 


10. Opeas octonoides. (C. B. Adams)... Antilles. ? Introduced. 
11, v5, . -Swittianum, - «(Pir,),;. ae. 

12. Ceecilioides acicula. (Miill. ) Europe and U. States. 
13. Pupa servilis. (Gld.) (= place West Indies, Yucatan. 


1 Fourteen species of Spiders were collected by Prof. A. Heilprin, all 
American or cosmopolitan species except one, Lycosa a/lantica, which Dr. 
Marx of Washington describes as new and as peculiar to the islands. 
(Heilprin’s The Bermudas, p. 93.) 


EE ———— Ee 


CHAP. XII BERMUDA 271 


14. Pupa jamaicensis. (C. B. Adams)... Jamaica. 


i | ,, , Tupicola, . (Say.) ue ... N. America. 
16. Pupoides marginatus. (Say.) ... N. America. 
°17. Ennea bicolor. (Hutton) ... ... Kast Indies. Introduced. 
18. Pa@cILozonITEs bermudensis. (Pfr.) A peculiar genus. 
19. a nelsoni. (Bland)... A sub-fossil species. 
20. we reinianus. (Pfr.)... 
21. circumpirmatus. (Redf.) 


22. Limax flavus. (L.)... 7 ... Probably introduced. 

23. Agriolinias lavis. (Miill.) ... By zs os 

24. Amalia gagates. (Drap.) ... net 5s ne 

25. Succinea barbadensis. (Guild.) ... West Indies. (This includes the 
three species of Succinea in 
former list. ) 

26. Veronicella schivelyze. (Pils.)  ... 

27. Onchidium floridanum. (Dall.) ... Florida. 

28. Helicina convexa. (VPfr.) ... ... Peculiar species. 


The above enumeration shows that six species are now 
held to be certainly peculiar to Bermuda, while four of 
them belong to a peculiar genus. If we deduct ten of the 
total number of species as having been introduced by 
human agency, bringing the number of endemic species to 
eighteen, we see that one-third of the whole have been so 
modified as to be classed as peculiar species, while almost 
all the other productions of the islands are identical with 
those of the nearest lands. This corresponds, however, - 
with what occurs generally in islands at a considerable 
distance from continents. In the Azores only one land- 
bird is peculiar out of eighteen resident species; the 
beetles show about one-eighth of the probably non- 
introduced species as peculiar; the plants about one- 
twentieth; while the land-shells have about half the 
species peculiar. This difference is well explained by 
the much greater difficulty of transmission over wide 
seas, In the case of land-shells, than of any other ter- 
restrial organisms. It thus happens that when a species 
has once been conveyed it may remain isolated for un- 
known ages, and has time to become modified by local 
conditions unchecked by the introduction of other in- 
dividuals of the original type. 

Flora of Bermuda.—Untfortunately no good account of 
the plants of these islands has yet been published. Mr. 
Jones, in his paper “ On the Vegetation of the Bermudas ” 


272 ISLAND LIFE PART II 


—————— “_o 


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 plants, in one undistinguished 
series. It appears 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 Mr. Hemsley estimates the indigenous species to be 
about 140. 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 Caribbean Sea, including the seeds of trees, shrubs, 
and other plants, which are continually cast ashore and 
sometimes vegetate. The soap-berry tree (Sapindus 
saponaria) has been actually observed to originate in this 
way. 

Mr. W. B. Hemsley considers that five of the flowering 
plants and three ferns are peculiar to the island, and he 
has kindly furnished me with the following list of these 
species :— 


Erigeron Darrelianus _... ... A composite plant. 
Statice Lefroyi ... ae ... A sea-lavender. 
Sisyrinchium bermudianum ..._ One of the Iris family. 
Sabal Blackburniana _... saa! A palm, 

Carex bermudiana ok ... A sedge. 

Adiantum bellum x .... A maiden-hair fern. 
Asplenium Laffanianum... ... <A fern. 

Nephrodium bermudianum ..._ A fern. 


The above are all of common and wide-spread types. 


ot 


r 
4 
: 
: 
‘ 
a 


4 


CHAP. XII BERMUDA 273 
The Sisyrmchium is hardly distinct from a North- 
American species. There are three species of Sabal, 
commonly called “ palmetto,’ in the Southern States. 
The sedge, however, is said to be allied to a St. Helena 
species. 

Mr. Moseley, who visited Bermuda in the Challenger, 
has well explained the probable origin of the vegetation. 
The large number of West Indian plants is no doubt due 
to the Gulf Stream and constant surface drift of warm 
water in this direction, while others have been brought by 
the annual cyclones which sweep over the intervening 
ocean. The great number of American migratory birds, 
including large flocks of the American golden plover, with 
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. In the first 
edition of this work published in 1880, Professor Oliver of 
the Kew Herbarium was not acquainted with a single 
species of flowering plant really peculiar to Bermuda. 
The researches of many botanists since that date have, as 
we have seen, discovered five, and, considering the small 
extent of the island and the fragmentary nature of its 
flora and fauna, there is probably little chance of adding 
to this number. 

Concluding Remarks.——The two 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 caught 
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 


1 **Notes on the Vegetation of Bermuda,” by H. N Moseley. (Journal 
of the Linnean Society, Vol. XIV., Botany, p. 317. 


T 


274 ISLAND LIFE PART II 
eroups— wrens, tits, creepers, and nuthatches—are absent ; 
while the number of annual visitors 1s greater in propor- 
tion as the migratory habits and prevalence of storms 
afford more efficient means for their introduction. 

We find also, that these great distances do not prevent 
the immigration of some insects of most of the orders, 
and especially of a considerable number and variety of 
beetles ; while even land-shells are fairly represented in 
both islands, the large proportion of peculiar species 
clearly indicating that, as we might expect, individuals of 
this group of organisms arrive only at long and irregular 
intervals. 

Plants are represented by a considerable variety of orders 
and genera, most of which show some special adaptation 
for dispersal by wind or water, or through the medium of 
birds; and there is no reason to doubt that besides the 
species that have actually established themselves, many 
others must have reached the 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 
origin, and that, notwithstanding all these disadvantages, 
they have acquired a very considerable and varied flora 
and fauna, we shall, I think, be convinced, that 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 XIII 


THE GALAPAGOS 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 Galapagos—Orig igin of the Flora of the Galapagos—Con- 
cluding Remarks, 


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 affected 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 their 
surface consists of barren lava-fields. 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 are 
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 important 
islands at a few miles distance, whence there appears to be 
a comparatively steep descent all round to the average 
depth of that portion of the Pacific, between 2,000 and 
8,000 fathoms. 


ge 


276 ISLAND LIFE PART II 


The whole group occupies a space of about 300 by 200 
It consists of five large and twelve small islands ; 


miles. 
the largest (Albemarle Island) bemg about eighty miles 


* QUITO 


nm 


| 
sal jaune itl Wd Ml My My, 


MAP OF THE GALAPAGOS AND 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 


CHAP. XIII THE GALAPAGOS ISLANDS 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 


3 INDLO Eo OWERL- => 


eoov-ls 


MAP OF THE GALAPAGOS: 


The light tint shows a depth of less than 1,000 fathoms. 
The figures show the depth in fathoms. 


comparatively calm sea, where storms are of rare occur- 
rence and even strong winds almost unknown. They are 
traversed by ocean currents which are strong and constant, 
flowing towards the north-west from the coast of Peru ; 


278 ISLAND LIFE PART II 


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 
Kuropeans, 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 difficult to account for. The 
vegetation is generally scanty, but still amply sufficient for 
the support of a considerable amount of animal life, as 
shown by the cattle, horses, asses, goats, pigs, dogs, and 
cats, which now run wild in some of the islands. 

Absence of Indigenous Mammalia and Amphibia.—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 recently 
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 Amphibia, are equally 
unknown. 

Reptiles.—Reptiles, however, which at first sight 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, 
Testudo microphyes, found in most of the islands, and 7. 


=e 


CHAP. XIII THE GALAPAGOS ISLANDS 279 


abingdonit recently discovered on Abingdon Island, as well 
as one extinct species, 7’. ephippium, found on Indefatigable 
Island. These are all of very large size, like the gigantic 
tortoises of the Mascarene Islands, from which, however, 
they differ in structural. characters; and Dr. Giinther 
believes that they have been originally derived from the 
American continent.' Considering the well known tenacity 
of life of these animals, and the large number of allied 
forms which have aquatic or sub-aquatic habits, it is not 
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 galapagensis, and four species of 
the American family Iguanide. 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 Amblyrhynchus cristatus by Mr. Bell, and 
A. subcristatus by Gray; they were afterwards placed in 
two other genera Trachycephalus and Oreocephalus (sce 
Brit. Mus. Catalogue of Lizards), while in a recent paper 
by Dr. Steindachner, the marine species is again classed as 
Amblyrhynchus, while the terrestrial form is placed in 
another genus Conolophus, both genera being peculiar to 
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 Gigantic Land Tortoises Living and Extinct in the Collection of the 
British Museum. By A. C. L. G. Giinther, F.R.S. 1877. 


280 ISLAND LIFE PART II 


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. (See Darwinism, 8rd ed. p. 374.) 

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. 
Over a hundred species of birds have now been obtained on 
these islands, and of these seventy-two are peculiar to them. 
But all the species found elsewhere, except three, belong to 
the aquatic tribes or the waders which are pre-eminently 
wanderers, yet even of these nine are peculiar. The true 
land-birds are sixty-six in number, and all but three are 
entirely confined to the Galapagos ; while nearly five-sixths 
of them present such peculiarities that they are classed in 
distinct genera though all are allied to birds inhabiting 
tropical America. Even the small number of the land- 
birds which inhabit the American continent should be 
reduced from three to two, since the rice-bird (Dolichonyx 
oryzivorus) was an accidental straggler which has never 
been found since Darwin obtained it on James Island. 

The following list of the land-birds, together with their 
distribution in the several islands, is extracted from Mr. 


CHAP. XIII 


THE GALAPAGOS ISLANDS 281 


Ridgway’s valuable memoir giving the result of the latest 
explorations.’ The few species which are not peculiar to 
the islands are in italics. 


List oF THE LAND-BIRDS OF THE GALAPAGOS. 


(The peculiar genera are in small capitals. ) 


Families. 

Turdidee i. 
2 

3 
— - 
5. 

6 

4 

8. 

Mniotiltide 9 


Coerebidee 10. 
11. 


Hirundinide 18. 


Fringillide 19. 
20. 
21. 
22. 
ya 
24. 
25. 
26. 


27. 
28. 


29. 
30. 
dl. 
32. 
30. 


34. 


30. 
36. 


1 ‘< Birds of the Galapagos Archipelago.”’ 


Species. 


NESOMIMUS trifasciatus 


9? 
be) 


macdonaldi 

adamsi, n.s. 
personatus .. 
melanotis ... 


parvulus 
bauri, n.s. 
bindloei, n.s. 


: Bendrieca aureola ... 


CERTHIDEA olivacea 


salvini, n.s. 
albemarlei, n.s. 
luteola, n.s. 
fusca ... 


ciner ascens, Nn. 5. 


mentalis, n.s. 


bifasciata, WS... 


Progne modesta 


GEOSPIZA magnirostris... 


strenua . 


padryr hyneha, n. . 


dubia 
conirostris 
bauri, n.s. 
media 
fortis 


fratercula, n.s. 
fuliginosa 


parvula..... ... 
acutirostris, n.s. 
dentirostris ... 
defficilis 


debilirostris, n.s. Ey 


CACTORNIS scandens 


vd) 


9? 


intermedia, n.s.... 


assimilis 


Vol. XIX. pp. 459-667 (1897). 


Remarks, 


Charles Is. only. 

Hood Is. 

Chatham Is. 

Abingdon Is. 

Indefatigable, Jervis,and 
James Is. 

Albemarle Is. 

Tower Is. 

Bindloe Is. 

All the Islands except 
Narborough, also in 
Ecuador. 

James Is. 

Indefatigable Is. 

Albemarle Is. 

Chatham Is. 

Abingdon Is. 

Hood Is. 

Tower Is. 

Barrington Is. 

Charles, Indefatigable, 
and James Is. 

Charles and Chatham Is. 

Six Eastern Islands. 


Tower Is. 


Chatham Is. 

Hood Is. 

James Is. 

Hood Is. 

Larger Is. (excl. Chat- 
ham and Narborough). 

Abingdon Is. 

Larger Is. (excl. 
borough). 

The Eastern Is. 

Tower Is. 

Charles Is. 

Abingdon Is. 

James Is. 

James Is. 

Charles Is. 

Bindloe Is. 


Nar- 


Proc. U.S. National Museum, 


282 ISLAND LIFE PART II 
Families. Species. Remarks. 

Fringillide 37. CACTORNIS fatigata, n.s. Indefatigable Is. 

38. x abingdoni Abingdon Is. 

39. ie barringdoni, n.s. Rarrington Is. 

40. a brevirostris .. Charles Is. 

41. propinqua, n.s. ... Tower Is. 

42. CAMARHYNCHUS variegatus... Albemarle Is. 

43. be crassirostris Albemarle to Chat- 
ham Is. 

44, 6 psittaculus Indefatigable, Jervis,and 
James Is. 

45. a affinis, n.s. Albemarle Is. 

46. fe habeli... Abingdon Is. 

47. 5 bindloei, n.s. Bindloe Is. 

48. compressiros- 

tris, n.s.... Jervis Is. 

49. = pauper Chailes Is. 

50. os incertus, n.s. James Is. 

51. s salvini, n.s. Chatham Is. 

52. sg prosthemelas Albemarle and _ three 
Eastern Is. 

53. $3 pallidus, n.s. Indefatigable, James and 
Jervis Is. 

54. re productus, 

N.S. Albemarle Is. 

Icteridz 55. Dolichonyx oryzivorus ... Canada to Paraguay. 
James Is., an acci- 
dental straggler. 

Tyrannide 56. Myiarchus magnirostris Albemarle and _ Kast- 
ward Is. 

57. Pyrocephalus nanus ... James Is. 

58. se intercedens, n.s. Albemarle and _ Inde- 
fatigable Is. 

59. x carolensis, n.s. | Charles Is. 

60. mS abingdoni, n.s. Abingdon Is. 

61. dubuis Chatham Is. 

Cuculidee 62. Cocca yzus melanocoryphus South America, Chat- 
ham Is. 

Columbide 63. Nesopelia galapagoensis Larger Is. (excl. Nar- 
boroughandChatham) 

Falconide 64. Buteo galapagoensis Larger Is. (excl. Nar- 
borough). 

Strigide 65. Strix punctatissima Indefatigable, James and 
Abingdon Is. 

66. Asio brachyotus Albemarle Is. eastward 
and almost cosmo- 
politan. 

WATER-BIRDS PECULIAR TO THE GALAPAGOS. 

Ardeidee 1. Butorides plumbens Albemarle Is. and east- 
ward. 

Anatide 2. Pacilonetta galapagoensis Albemarle Is. and east- 
ward. 

Rallide 3, Porzana spilonota ... James and _ Indefati- 


gable Is. 


CHAP. XIII THE GALAPAGOS ISLANDS 283 


Families. Species. Remarks. 
Rallide. 4. Porzana galapagoensis ... ... Rare, loc. unknown. 
5. Hematopus galapagoensis ... Albemarle Is. eastward. 
Laride 6. Anous galapagoensis ... ... Albemarle Js. eastward. 
Procellariide 7. Oestralata pheopygia ... ... Galapagos Archipelago. 
8. Puffinus subalaris...... ... Galapagos Archipelago. 
Spheniscide 9. Spheniscus mendiculus... ... Albemarle, Charles and 
James Is. 


We have here every gradation of difference from perfect 
identity with the continental species to genera so distinct 
that it is difficult to determine with what forms they are 
most nearly allied ; and it is interesting to note that this 
diversity bears a distinct relation to the probabilities of, 
and facilities for, migration to the islands. First, we have 
the almost cosmopolite short-eared owl (Asio brachyotus), 
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 slight varieties. 
The little wood warbler (Dendraca aureola) is a species 
which is found also in Ecuador. The more distinct species 
—as the tyrant fly-catchers (Pyrocephalus and Myiarchus), 
the ground-dove (Zenaida), and the Buzzard (Buteo), are 
all allied to non-migratory species peculiar to tropical 
America, and of a more restricted range; while the 
distinct genera 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 
-exceptionable 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 conditions of existence 
under which they have been placed. It is remarkable 
how often the different species thus formed are confined 
to one island only. Thus, the eight species of Certhidea 
each inhabit a single island. The same is the case with 
seven of the eight thrushes, and with a large proportion 
of the finches, so that no less than forty-seven out of the 
sixty-three peculiar land-birds are at present known to 
inhabit only one island. 

Now all these phenomena are strictly consistent with 


284 ISLAND LIFE PART II 


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 antiquity. 

The great difference presented by the birds of these 
islands as compared with those of the equally 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- 
migratory, and thus afford none of the opportunities 
presented by the countless hosts of migrants which pass 
annually northward and southward along the European, 
and especially along the North American coasts. It is 
strictly in accordance with these different conditions that 
we find in one case an almost perfect indentity 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-wide groups. The 
Carabide and the Heteromera are the most abundant 
groups, the former furnishing six and the latter nine 
species.? 

The land-shells are not abundant—about forty-six in all, 
belonging to ten genera, but two-thirds of the whole are 
Bulimuli, and there is no peculiar genus, although almost 


1 The following list of the beetles yet known from the Galapagos show 
their scanty proportions and accidental character ; the forty species be- 
longing to thirty-three genera and eighteen families. It is taken from 
Mr. Waterhouse’s enumeration in the Proceedings of the Zoological Society 


CHAP. XIII THE GALAPAGOS ISLANDS 285 


all the species are peculiar. The observation of Captain 
Collnet, quoted by Mr. Darwin in his Journal, that. drift- 
wood, bamboos, canes, and the nuts of a palm, are often 
washed on the south-eastern shores of the islands, 
furnishes an excellent clue 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 débris to great 
heights in the air, and these might be then 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 quite 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 


for 1877 (p. 81), with a few additions collected by the U.S. Fish Com- 
mission Steamer Albatross, and published by the U.S. National Museum 
in 1889. 


CARABIDA. ELATERIDZ. 
Feronia calathoides. . Physorhinus galapagoensis. 
oP insularis. HETEROMERA. 

i galapagoensis. Allecula n. s. 
Amblygnathus obscuricornis. Stomion helopoides. 
Solenophorus galapagoensis. is levigatum. 
Notaphus galapagoensis. Ammophorus obscurus, 

DyTISCcID. 3 cooksoni. 
Eunectes occidentalis. <5 bifoveatus. 
Acilius incisus. Pedoneeces galapagoensis. 
Copelatus galapagoensis. » pubescens. 

PALPICORNES. Phaleria manicata. 
Tropisternus lateralis. CURCULIONIDS. 


Philhydrus sp. 
STAPHYLINIDA. 
Creophilus villosus. 
NECROPHAGA. 
Acribis serrativentris. 
Phalacrus darwinii. 
Dermestes vulpinus. 
MALACODERMS. 
Ablechrus darwinii. 
Corynetes rufipes. 


Bustrichus unciniatus. 


Tetrapriocerca sp. 
LAMELLICORNES. 
Copris lugubris. 


Oryctes galapagoensis. 


Otiorhynchus cuneiformis. 
Anchonus galapagoensis. 
LONGICORNIA. 
Mallodou sp. 
Eburia amabilis. 
ANTHRIBIDA. 
Ormiscus variegatus. 
PHYTOPHAGA. 
Diabrotica limbata. 
Docema galapagoensis. 
Longitarsus lunatus. 
SECURIPALPES. 
Scymuns galapagoensis. 


286 ISLAND LIFE PART II 


passage to them of various organisms would be greatly 
facilitated. Sunken banks, the relics of such islands, are 
known to exist in many parts of the ocean, and countless 
others, no doubt, remain undiscovered. 

The Keeling Islands as Illustrating the Manner in which 
Oceanre 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 vegetation. These islands were visited by Mr. 
Darwin, and their 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 difference 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 
Diopszea 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 only 
twenty species were found belonging to nineteen genera 


i el — = = 


CHAP, XIII THE GALAPAGOS ISLANDS 287 


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 
winds and waves; but their scanty vegetation is mainly 
due to unfavourable conditions—the barren coral rock of 
which they are wholly composed being suitable to very 
few species, while the numerous crabs destroy the young 


shoots unless in some way protected. With more variety 


of soil and aspect a greater number of plants would 
establish themselves, and these would favour the preserva- 
tion and increase of more insects, birds, and other animals, 
as we find to be the case in other small and remote 
islands.? 


1 Mr. H. O. Forbes, who visited these islands in 1878, and Dr. Guppy 
in 1889, have increased the number of wild plants to over forty, and 
these belonged to twenty-six natural orders. 

2 Juan Fernandez is a good example of a small island which, with time 
and favourable conditions, has acquired a tolerably rich and highly peculiar 
flora and fauna. It is situated in 34° S. Lat., 400 miles from the coast 
of Chile, and so far as facilities for the transport of living organisms are 
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, offering 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 though 
only about twelve miles long its mountains are three thousand feet high. 
Enjoying a moist and temperate climate it is especially adapted to the 
erowth 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 forty-two species on the island, while the 
remote period when it first received its vegetation may be indicated by the 
fact that seven of the species are quite peculiar ; while of 102 species of 
flowering plants sixty-two are peculiar, and there are eleven peculiar 
genera. ‘The same general character pervades the fauna. For so small 
and remote an island it is rich, containing four true land-birds, ahout 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 trans- 
mission were formerly greater than they are now, and that in the case of 
land-shells none have been introduced for so long a period that all have 
become modified into distinct forms, or have been preserved on the island 
while they have become extinct on the continent. For a fuller account 
of the fauna of the island see the author’s Geographical Distribution of 
Animals, Vol. II. p. 49, and for the peculiar humming-birds, Natural 
Selection and Tropical Nature, pp. 324—329. The account of the flora 


288 ISLAND LIFE PART II 


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 Joseph 
Hooker in the Linnean Transactions for 1851, founded 
on Mr. Darwin’s collections, and a later paper by N. J. 
Andersson in the Linnea of 1861, embodying more recent 
discoveries. 

The total number of flowering plants and ferns known at 
the latter date was 332, of which 174 were peculiar to the 
islands, while 158 were common to other countries. Of 
these latter at least 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 wide 
range extending into both hemispheres. 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 with the 
observation of Sir Joseph Hooker that the peculiar species 
are allied to the plants of temperate America or to those 
of the high Andes, while the non-peculiar species are 
mostly such as inhabit the hotter regions of the tropics 
near the level of the sea. Healso observes that the seeds 
of this latter class of Galapagos plants often have special 
means of transport, or belong to groups whose seeds are 
known to stand long voyages and to possess great vitality. 
Mr Bentham also, in his elaborate account of the Com- 
posite,? remarks on the decided Central American or 


is derived from the fine work of Professor Federico Johow, Flora de las 
Islas de Juan Fernandez, 1896 ; published by the Chilian Government. 

1 No additions appear to have been made to this flora down to 1900, 
when Mr. Hemsley gave a general account of the botany of the islands 
in the Gardener’s Chronicle, p. 177. 

2 Journal of the Linnean Society, Vol. XIII., ‘‘ Botany,” p. 556. 


CHAP. XIII THE GALAPAGOS ISLANDS 289 


Mexican affinities of the Galapagos species, so that we may 
consider this to be a thoroughly well-established fact. 

The most prevalent families of plants in the Galapagos 
are the Composite (40 sp.), Graminez (32 sp.), Legumi- 
nos (30 sp.), and Euphorbiacesze (29 sp.). Of the Com- 
positze 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; while the genus Lipocheta, represented 
here by a single species, is only found elsewhere in the 
Sandwich Islands though it has American affinities. 

Origin of the Galapagos Flora——These facts are ex- 
plained by the past history of the American continent, its 
separation at various epochs by arms of the sea uniting the 
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 
finally passed away, while throughout the Miocene epoch 
the snow-line would 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 species. 
On the whole, the flora agrees with the fauna in in- 
dicating a moderately remote origin, great isolation, and 
changes of conditions affording facilities for the introduc- 
tion of organisms from various parts of the American 


1 Geographical Distribution of Animals, Vol. II. p. 81. 
[3 


290 ISLAND LIFE PART II 


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 
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 mast part confine ourselves to this aspect of the 
question in. our discussion of the phenomena presented by 
oceanic or vontinental islands. 

Concluding Remarks.—The Galapagos offer an instructive 
contrast with the Azores, showing how a difference of con- 
ditions that might be thought 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- 


eat 
oy Soares 


CHAP. XIII THE GALAPAGOS ISLANDS 991 


drifts are undoubtedly efficient carriers of plants, and, with 
plants, of insects and shells, especially in the tropics; and 
it is probably to this agency that we may impute the 


recent introduction of a number of common Peruvian and 


Chilian littoral species, and also 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 tem- 
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 fact 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, 1s 
equally intelligible. The reason why the Galapagos pos- 
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 specifi« 
change; and the influence of cold epochs and of alterations 
of sea and land, in bringing somewhat different sets of 
plants at different times within the influence of such 
modified winds and currents as might convey them to the 
islands. | 

On the whole, then, we have no difficulty in explaining 
the probable origin of the flora and fauna of the Galapagos, 
by means of the illustrative facts and general principles 
already adduced. 


CHAPTER XIV 


ST. HELENA 


Position and Physical Features 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—Native Vegetation of St. 
Helena—The Relations of the St. Helena Compositee—Concluding 
Remarks on St. Helena. 


IN order to illustrate as completely as possible the pecuhar 
phenomena of oceanic islands, we will next examine the 
organic productions of St. Helena and of the Sandwich 
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 peculiarities 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 


the 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, 1s 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 plateau, 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 very much 


_ larger than it is at present—the comparatively shallow 
- sea-soundings within 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 by European Occupation—When first 
discovered, in the year 1501, St. Helena was densely 
covered with a luxuriant forest vegetation, the trees over- 
hanging the seaward precipices and covering every part of 
the surface with 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, — 


= 
ia 
nd 
uy 
. 


~ EN om 


CHAP. XIV ST. HELENA 295 


yet the general aspect of the island is now so barren 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. The 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 tropical 


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 1513, and increased 
so rapidly that in 1588, they existed in thousands. These 
animals are the greatest of all foes to trees, because they 
eat 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,! it 
is evident that the evil consequences of allowing the trees 
to be destroyed were clearly foreseen, as the following 
passages show : “ We find the place called the Great Wood 
in a flourishing condition, full of young trees, where the 
hoges (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 (scription of 


the Island, &c. By John Charles Melliss, F.G.8., &c. London: 1875. 


296 ISLAND LIFE PART II 


chose out their settlements and made plantations ; but if 
wells could be sunk, which the governor says he will 
attempt when we have more hands, we should then think 
it the most pleasant and healthiest part of the island. 
But as to healthiness, we don’t think it will hold so if the 
wood that keeps the land warm were destroyed, for then 
the rains, which are violent here, would carry away the 
upper soil, and it being a clay marl underneath would 
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 will 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 by 
Human Action (p. 51), thus remarks on the effect of browsing quadrupeds 
in destroying and checking woody vegetation.—‘‘I am convinced that 
forests would 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 off 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, except, 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 
shrubs shoot up, but are mown down by the hungry cattle of the Bedouin 


CHAP. XIV ST. HELENA 297 


pecuniary point of view the error was a fatal one, for in the 


next century (in 1810) another governor reports the total 


destruction of the great forests by the goats, and that in 
consequence the cost of importing fuel for government use 
was 2,/29/. 7s. 8d. 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 almost 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. Many 
naturalists have made small collections during short visits, 
but we owe our present complete knowledge of the two 
most interesting groups of animals, the insects, and the 
land-shells, mainly to the late Mr. T. Vernon Wollaston, 
who, after having thoroughly explored Madeira and the 
Canaries, undertook a voyage to St. Helena for the express 
purpose of studying its terrestrial fauna, and resided for six 
months (1875-76) in a high central position, whence the 
loftiest peaks could be explored. The results of his labours 
are contained in two volumes,! which, like all that he 
wrote, 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 suffice 
to cover such points with groves, and these would gradually extend them- 
selves over soils where now scarcely any green thing but the bitter 


- colocynth and the poisonous foxglove is ever seen.” 


-1 Coleoptera Sancte Helene, 1877 ; Testacea Atlantica, 1878. 


298 ISLAND LIFE PART II 


Insects — Coleoptera.—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 wide-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 
Cossonide. 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 1s the fact that the twenty 
genera to which 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 


ae a 


n ei ee _? 


CHAP. XIV ST. HELENA 299 


systematic order, but according to their importance in the 
island. | 

_ 1. RayncopHorsa.—This great division includes the 
weevils and allied groups, and, as above stated, exceeds in 
number of species all the other beetles of the island. Four 
families are represented; the Cossonide, with fifteen 
peculiar genera comprising fifty-four species, and one 
minute insect (Stenoscelis hylastoides) forming a peculiar 
genus, but which has been found also at the Cape 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 Cossonide are found 
in the highest aiid wildest parts of the island where the 
native vegetation still lingers, and many of them are only 
found in the decaying stems of tree-ferns, box-wood, 
arborescent Composite, 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 Tanyrhynchide, has one peculiar 
genus in St. Helena, with ten species. This genus (Nesiotes) 
is remotely allied to European, Australian, and Madeiran 
insects of the same family : the habits of the species are 
similar to those of the Cossonide. The Trachyphlceide are 
represented by a single species belonging to a peculiar 
genus not very remote from a European form. The An- 
thribidz 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 carnivorous 
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 Haplothorax 
burchelliz, the largest beetle on the island, and now very 
rare. It resembles a large black Carabus. There is also 
a peculiar Calosoma, very distinct, though resembling in 
some respects certain African species. The rest of the 


300 ISLAND LIFE PART II 


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 
Opatride, Mordellide, and Anthicide. 

4, BRACHYELYTRA.—Of this group there are six peculiar 
species belonging to four European genera—Homalota, 
Philonthus, Xantholinus, and Oxytelus. 

5. PRIOCERATA—The families Elateride and Anobiide 
are each represented by a peculiar species of a European 
genus. 

6. PHyToPpHAGA.—There are only three species of this 
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-TRIMERA.—Here we have the fine lad 74 
Chilomenus 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. TRICHOPTERYGIDZ.—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. 

Peculiarities and Origin of the Coleoptera of St. Helena.— 
We see that the great mass of the indigenous species are 
not only peculiar to the island, but so isolated in their 
characters as to show no close affinity with any existing 
insects; while a small number (about one-third of the 
whole) have some relations, though often very remote, 
with species now 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 


CHAP. XIV ST. HELENA 801 
sg ee eo 
time for the modification of the originally introduced 
species, and their special adaptation to the conditions pre- 
vailing in this remote island. This antiquity is also shown 
by the remarkable specific modification of a few types. 
Thus the whole of the Cossonide may be referred to three 
types, one species only (Hexacoptus ferrugineus) being allied 
to the European Cossonide though forming a distinct 
genus ; a group of three genera and seven species remotely 
allied to the Stenoscelis hylastoides, which occurs also at the 
Cape; while a group of twelve genera with forty-six species 
have their only (remote) allies in a few insects widely 
scattered in South Africa, New Zealand, Europe, and the 
Atlantic Islands. In like manner, eleven species of Bem- 
bidium form a group by themselves; and the Heteromera 
form two groups, one consisting of three genera and species 
of Opatridz allied 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 
other land ; and the great variety of generic and specific 
forms into which some of them have diverged is an indica- 
tion, and to some extenta measure, of the remoteness of their 
origin. The rich insect fauna of Miocene age found in 
Switzerland consists mostly of genera which still inhabit 
Kurope, 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 difficulties in 
accounting for its origin will disappear. We know that 
at that time many of the animals and plants of the tropics, 
of North America, and even of Australia, inhabited 
Europe; while during the changes of climate, which, as 
we have seen, there is good reason to believe periodically 
occurred, there would be much migration from the tem- 
perate zones towards the equator, and the reverse. If, 
therefore, the nearest ally of any insular group now in- 
habits a particular country, we are not obliged to suppose 
that it reached the island from that country, since we 
know that most groups have ranged in past times over 


aaa ISLAND LIFE PART II 


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 North Atlantic islands and Southern 
Europe ; but it is not at all improbable that they are really 
widespread Miocene types, which have been preserved 
mainly in favourable insular stations. They may there- 
fore have originally reached St. Helena from Southern 
Africa, or from some of the Atlantic islands, and may have 
been conveyed by oceanic currents as well as by winds. 
This is the more probable, as a large proportion of the St. 
Helena beetles live even in the perfect state within the 
stems of plants or trunks of trees, while the eggs and 
larvee of a still larger number are likely to inhabit similar 
stations. Drift-wood might therefore be one of the most 
‘important agencies by which these insects reached the 
island. 

Let us now see how far the distribution of other groups 
support the conclusions derived from a consideration of the 
beetles. The Hemiptera have been studied by Dr. F. 
Buchanan White, and though far less known than the 
beetles, indicate somewhat similar relations. Hight 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 


1 On Petermann’s map of Africa, in Stieler’s Hand-Atlas (1879), the 
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 probable that 
a much larger island once occupied this site. Now Ascension is nearly 
equidistant between St. Helena and Liberia, and such an island might 
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 whatever difficulty may have been 
felt of the possibility of any organisms reaching so remote an island. 
The present island of Ascension is probably only the summit of a huge 
volcanic mass, and any remnant of the original fauna and flora it might 
have preserved may have been destroyed by great volcanic eruptions. Mr. 
Darwin collected some masses of tufa which were found to be mainly 
organic, containing, besides remains of fresh-water infusoria, the siliceous 
tissue of plants! In the light of the great extent of the submarine bank 
on which the island stands, Mr. Darwin’s remark, that—‘* we may feel 
sure, that at some former epoch, the climate and productions of Ascension 
were very different from what they are now,”—has received a striking 
confirmation. (See Naturalist’s Voyage Rownd the World, p. 495.) 


304 ISLAND LIFE - PART II. 


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 ground or in the surface soil in places 
where the native forests have been destroyed and the land 
not cultivated. These twenty peculiar species belong to 
the followmg genera: Hyalina (3 sp.), Patula (4 sp.), 
Bulimus (7 sp.), Subulina (8 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 vulpine and B. darwinianus) 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 Kuropean 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 Fresh-water 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 
he any water-plants in the streams, except the common 


OHAP. XIV ST. HELENA 8305 


water-cress, one or two species of Cyperus, and the 
Australian Jsapis prolifera. The same absence of fresh- 
water shells characterises the Azores, where, however, there 
is one indigenous water-beetle. In the Sandwich Islands 
also recent observations refer to the absence of water- 
beetles, though here there are a few fresh-water shells. It 
would appear therefore that the wide distribution of the 
same generic and specific forms which so generally 
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 (Wgialitis sanctw-helene) 
-—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. 

Native Vegetation of St. Helena.—Plants have certainly 
more varied and more effectual means of passing over wide 
tracts of ocean than any kinds of animals. Their seeds are 
often so minute, of such 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 them to 
become easily attached to the feathers of aquatic birds, and 
they may thus be conveyed for thousands of miles by these 
pre-eminent wanderers ; while many seeds are so protected 
by hard outer coats and dense inner albumen, that months 
of exposure to salt water does not prevent them from 
germinating, as proved by the West Indian seeds that 
reach the Azores or even the west coast of Scotland, and, 
what is more to the point, by the fact stated by Mr. 
Melliss, that large seeds which have floated from 

x 


306 ISLAND 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 how 
the island was first stocked with vegetable forms. When 
it was so stocked (generally speaking), 1s equally clear. 
For as the peculiar coleopterous fauna, of which an im- 
portant fragment remains, is mainly composed of species 
which are specially attached to certain groups of plants, we 
may be sure that the plants were there long before the 
insects could establish themselves. 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 occupy 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 would be of an excessively ancient 
type, preserving for us in a slightly modified form 
examples of the vegetation of the globe at the time when 
the island first rose above the ocean. Let us see then 
what botanists tell us of its character and affinities. 

The truly indigenous flowering plants 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 Joseph 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, 


CHAP. XIV ST. HELENA =. 307 


mainly African and especially South African, as indicated 
by the presence of the genera Phylica, Pelargonium, 
Mesembryanthemum, Oteospermum, and Wahlenbergia, 
which are eminently characteristic of southern extra-tropical 
Africa. The sixteen ferns which are not peculiar are 
common either to Africa, India, or America, a wide range 
sufficiently explained by the dust-like spores of ferns, 
capable of being carried to 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 species of ferns between St. 
Helena and distant countries does not necessarily imply a 
recent origin. 

The elation of the St. Helena Composite.—In an 
elaborate paper on the Compositz,! 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 the 
Australian Olearia. Petrobium is one of three genera, 
remains of a group probably of great antiquity, of which 
the two others are Podanthus in Chile and Astemma in 
the Andes, The Pisiadia is an endemic species of a genus 
otherwise Mascarene or of Eastern Africa, presenting a 
geographical connection analogous to that of the St. Helena 
Melhaniz,? with the Mascarene Trochetia.” 

Whenever such remote and singular cases of geo- 
graphical affinity as the above are pointed out, the first 


1 «Notes on the Classification, History, and Geographical Distribution 
of Composite.” — Journal of the Linnean Society, Vol. XIII. p. 563 (1878). 

2 The Melhaniz comprise the two finest timber trees of St. Helena, now 
almost extinct, the redwood and native ebony. 


x 2 


308 ISLAND LIFE PART II 


impression is to 1magine some mode by which a com- 
munication between the distant countries implicated 
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- 
graphical 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 Equidz in South Africa and extinct Equide in the 
Pliocene deposits of the Pampas, imply a continent 
bridging the South Atlantic to allow of their easy com- 
munication. 

Concluding Remarks 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 preserved 
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 


ane CIN ae ORE Re Ay 


[AP, XIV ST. HELENA 309 


od, or even earlier, had been saved from the destruc- 
a hich has overtaken their allies on the great con- 
nents. Unfortunately many, we do not know how 
any, of these forms have been exterminated by the 
r elessness and improvidence of its civilised but ignorant 
rs; and it is only by the extreme ruggedness and 
ecessibility of its peaks and crater-ridges that the 
nty fragments have escaped by which alone we are 
e to obtain a glimpse of this interesting chapter in the 
life-history of our earth. 


FE 4 
hal 
- uw 
. ° 
a 
- 


CHAPTER XV 


THE SANDWICH ISLANDS 


Position and Physical Features—Zoology of the Sandwich 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. 


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 are 
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. 


Se 


CHAP. XV THE SANDWICH ISLANDS dll 


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 the largest island is rendered 


mn; 


i ( 


liso w “lI69 lis : a ‘ 


MAP OF THE SANDWICH ISLANDS. 


The light tint shows where the sea is less than 1,000 fathoms deep. 
The figures show the depth in fathoms. 


sterile and comparatively uninhabitable by its three active 
volcanoes and their widespread deposits of lava. 

The ocean depths by which these islands are separated 
from the nearest continents are enormous. North, east, 
and south, soundings have been obtained a little over or 
under three thousand fathoms, and these profound deeps 
extend over a large part of the North Pacific. We may 


co 


12 ISLAND LIFE PART II 


be quite sure, therefore, that the Sandwich Islands have, 
during their whole existence, been as completely severed 
from the great continents as they are now; but on the 


MAP OF THE NORTH PACIFIC WITH ITS SUBMERGED BANKS. 


The light tint shows where the sea is less than 1,000 fathoms deep. 
The dark tint _,, = 3 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 


CHAP. XV THE SANDWICH ISLANDS 313 


considerable areas of less depth, varying from two hundred 
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 banks, 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 view 
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 depths 
have gradually built up the islands which now dot its 
surface, as well as many others which have sunk beneath 
its waves. The number of islands, as well as the total 
quantity of land-surface, may sometimes have been 
greater than it is now, and may thus have facilitated the 
transfer of organisms from one group to another, and more 
rarely even from the American, Asiatic, or Australian 
continents. Keeping these various facts and considera- 
tions in view, we may now proceed to examine the fauna 
and flora of the Sandwich Islands, and discuss the special 
phenomena they present. - 

Zoology of the Sandwich Islands: Birds.—It need hardly 
be said that indigenous mammalia are quite unknown in 
the Sandwich Islands, the most interesting of the higher 
animals being the birds, which are tolerably numerous and 
highly peculiar. Many aquatic and wading birds which 
range over the whole Pacific visit these islands, fifty-eight 
species having been observed, but even of these six are 
peculiar—a coot, Fulica alai ; a moorhen, Gallinula galeata 
var. sundvichensis ; a rail with rudimentary wings, Pen- 
nula ecaudata ; a stilt-plover Himantopus knudsent ; and 


314 ISLAND LIFE PAhT II 


two ducks, Anas Wyvilliana and Bernicla sandvichensis. 
The birds of prey are also great wanderers. Four have 
been found in the islands—the short-eared owl, Otus 
brachyotus, 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, 
Accipiter hawaii ,;.and a buzzard of a peculiar species, 
Buteo solitarius, coloured so as to resemble a hawk of the 
American sub-family Polyborine. It 1s 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 imcreased 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 in 1887 for the purpose 
of investigating their ornithology, and collected assiduously 
in the various islands of the group for a year and a half, 
and he also made a second journey in 1896. 

In 1892 a Committee of the British Association sent 
out Mr. R. C. L. Perkins, of the Cambridge Museum of 
Zoology, who also made two separate visits of nearly two 
years each, and obtained a_ considerable number of 
novelties. These together with the results of other 
private collections are described in a fine work, Aves 
Hawatienses, by Mr. Scott Wilson, who has also furnished 
me with a few of the latest additions to the fauna, so 
that the following list embodies all the available informa- 
tion down to the present year, 1901. A fewalterations in 
nomenclature have, however, been made in accordance with 
a very valuable paper on the Drepanidide by Mr. R. C. L. 
Perkins in the /bis of October, 1901, in which the habits, 
classification, and distribution of this extremely interest- 
ing family are very fully discussed. 7 


CHAP. XV THE SANDWICH ISLANDS 315 
PASSERES OF THE SANDWICH ISLANDs. 
CoRVIDZ. 
Ti OOrvtis TOPICUS  ...0.0000sceeeseaces Hawaii. 
DREPANIDID&. 

2. DPeEPaNis PIciied......5...62200c0en-. Hawaii ; probably extinct. 

3. Drepanorhamphus funereus ...... Molokai. 

4. -V CStIATIA, COCCINED. . 1.00005 00000000 All the Islands. 

5. Palmeria dolii ......................... Maui and Molokai. 

6. Himatione sanguinea ............... All the Islands. 

ep PIG ODS BNA: ose Sect hogs anand Hawaii ; probably extinct. 

8. Chlorodrepanis stejnegeri.......... Kauai 

9. # CRIGTES Sides scdies Oahu 

10. Me chloridoides ...... Lanai. Mr. Perkins con- 
i. a [os ea Molokai. rsiders these to be all 
12. BY WAROUA | oo 28dioadeek Hawaii. | varieties of C. virens. 
13. WHSOTE 9. o. ovc¥s esc Maui. 

14. Rothschildia gy oe ee eee ve Matai. 

15. Viridonia sagittirostris............. Hawaii. 

Mee 7 en ere Kauai. 

17. ne MATAWOR 2.553 oc8as Molokai. 

18. 3 HOGEORD .5.505.5)05..c: Maui 

19. “ a a ae Oahu 

20. ns POM UIUA sien e cinesies data vie- Lanai 

ay: & eo peer een eae Ee Hawall 

22. = Wis: $58 we white Maui. 

23. perkinsi ....,......60009-+. Hawaii 

24. Loxops PBECINOR' | 3,2:05113¥eerncoeenee Hawaii. 

25. D> Mitac. ae hoe Bee MEN gh a RE Oahu ; probably extinct 

26. at Th CERO 8. 5552 casas dea Maui. 

ai. ath EIT OWLT ES os eiadniesccce «6 de Kauai 

28. Hemignathus procerus ............ Kauai. 

29. ¥ ellisiamus ............ Oahu ; probably extinct 

30. mA GDSGUTUS: «... 60.02 cs Hawaii. 

31. LANA CUSA «oss. Lanai. 

32. Heterorhynchus POTOUN, 632 coins cas Oahu ; probably extinct 

33. an WISONE.. 5. ...50i6% Hawaii. 

34, is PT 343-6 Maui 

35. hanapepe... ...... Kauai 

36. Pseudonestor xanthophrys......... Maui. 

37. Psittacirostra psittacea ............. Kaui, Molokai, Lanai, Hawaii. 
38. oliyacea ...:.......... Maui. 

39. Loxioides bailleui ........0..0....-.. Hawaii. 
40. Rhodacanthfs palmeri............... Hawaii 

41. POWICEpS 0. 6si5.0702 Hawaii 
42. Chloridops DUM Sisle sda 408s. Py Hawaii 
MELIPHAGIDZ. 

43. Acrulocercus braccatus ........ ... Kauai. 
44, Es apicalis ................ Oahu; probably extinct. 


315a ISLAND LIFE PART II 


45. Acrulocercus nobilis ..........20.006 Hawaii 

46. as PRIVOT cheese ceisaiee Molokai 

47. Chetoptila angustipluma ......... Hawaii; probably extinct 

TURDIDZ. 

48. Pheornis myladestina............... Kauai. 

49, A PSAMIGTISIS. os scene Molokai, Lanai. 

50. i BUSOUCH, Velo ca ees oh ae Hawaii. 

Bi: mn CEE mo, as een see Kauai. 

52. ve PEMUCMSIS A occsax settee Oahu ; probably extinct. 
MUSCICAPIDA. 

53. Chasiempis sandvichensis ......... Hawaii. 

54, my DANE Aucune eee: Oahu. 

he hah Belatere Ait kane ese Kauai. 


The preceding list differs considerably from that given 
in the last edition of this volume, not only by the increase 
of the species from 37 to 55, but in the omission of the 
finch family altogether. This has been done because a 
careful examination by Dr. Hans Gadow of the structure 
of the three birds formerly so classed, from specimens 
preserved in spirits, has shown that all three, and some 
other species since discovered, are really allied to the 
curious little birds forming the peculiar family Drepani- 
didz, which now comprise twelve genera and forty-one 
species. The same conclusion was first reached by Mr. 
Perkins, who carefully observed the motions and habits of 
the birds in question, and found such a curious similarity 
that he was satisfied they belonged to one group. 

From a consideration of the whole structure of this 
interesting family, Dr. Gadow considers them to be most 
nearly allied to the Coerebidee, and perhaps also to the 
Tanagride, both peculiar American families. This fact, 
if correct, greatly modifies the conclusion hitherto reached, 
that the general affinities of Sandwich Island birds were 
Australasian rather than American. The Meliphagide or 
honeysuckers, a specially abundant group throughout 
Australasia, are only represented by five species, and the 
Muscicapide or flycatchers, also abundant in Australasia 
as well as in all the continents except America, only by 


CHAP. xv THE SANDWICH ISLANDS 316 


three species. Again, there are three groups of birds 


which are exceptionally abundant in Australasia—the 


parrots, pigeons, and kingfishers—and are found in all 
the larger Pacific Islands as far as the Marquesas; yet 
not a single species of either of them inhabits the Sand- 
wich Islands. But such strange facts as these are not 
conclusive as to the region to which these islands belong, 
if indeed they can be said to belong to any region. All 
they prove is that the group is and has been from its origin 
extremely isolated, that it has received immigrants at 
rare intervals from all directions, but that those descended 
from an American type appear to have been among the 
earliest to establish themselves and the best adapted to 
the peculiar conditions that prevailed in their new home, 
so that they have diverged into the varied and numerous 
forms we now find there. But it still remains the fact 
that two families which are fairly represented, the honey- 
suckers and the true flycatchers, have been derived from 
the Australian region, and are absolutely unknown in the 
whole American continent. 

The amount of speciality is, however, wonderful, far 
exceeding that of any other islands ; the only approach to 
it being made by New Zeaiand and Madagascar, which 
have a much more varied bird fauna and a smaller pro- 
portionate number of peculiar genera. The Galapagos, 
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 which 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 the Sandwich Islands, 
already alluded to. 

feptiles—The only other vertebrate animals are two 
lizards. One of these is a very widespread species 
Ablepharus pecilopleurus, ranging from the Pacific Islands 
to West Africa. The other is said to form a peculiar 


317 ISLAND LIFE PART II 


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 which presents features of 
especial interest, are the land and freshwater. shells. 
These are very numerous, about thirty-five genera, and 
nearly five hundred species having been described ; and 
it is remarkable that this single archipelago contains as 
many species of these molluscs as all the other Polynesian 
Islands from the Pelew Islands and Samoa to the 
Marquesas. Almost all the species are peculiar, and more 
than three-fourths of the whole belong to peculiar genera, 
nine of which constitute the family Achatinellide, almost 
confined to this group of islands and constituting its most 
distinguishing feature.’ Only nine species are found in 
other parts of the world, and several of these (possibly 
all) are recent introductions. 

The Rev. John T. Gulick, who has made a special study 
of the Achatinellide, 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 


1 The genus Partula of the South Pacific Islands is sometimes classed 
with the Achatinellide, but this is not considered certain. 

2 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 
Achatinellide.” 


CHAP. XV THE SANDWICH ISLANDS 317a 


species of Achatinellide, represented by 700 or 800 
varieties. Of the other islands Maui has most peculiar 
‘species; and of the total of 468 endemic species, 395 are 
known from one island only. But even this large number 
does not fully represent the restricted range of the species, 
since about twenty more are only recorded as from the 
“ Sandwich Islands,” and as none of these have been found 
by recent collectors they are probably very rare and each 
confined to one island, or are possibly now extinct. It 
follows that nearly nine-tenths of the endemic species are 
limited in their range each to one island only. 

Mr. E. R. Sykes, who has furnished the most recent 
systematic account of these molluscs in the Fauna 
Hawanensis (Vol. IL, 1900), gives his general conclusions 
as follows :— 

(1) The Molluscan fauna is nearly related to that of the 
Polynesian Islands, and shows hardly any trace of con- 
tinental influence, Asiatic or American. 

(2) The species are nearly always confined to one 
island ; but it is very doubtful if, as has been stated, “ each 
valley has its peculiar species.” 

(3) In the genera confined to the islands, the majority 
of the living species usually occur in Oahu. 

Equally interesting with the restricted range of the 
species is that of some of the sub-genera and even of 
the genera. The sub-genus Achatinella with 17 species 
and many named varieties is entirely confined to Oahu, 
as is the sub-genus Bulimella with 20 species. The genus 
Carelia, also belonging to the Achatinellide, is confined 
to Kaui, except one species in its neighbouring 
small island Niihau, which may be looked upon as its 
satellite, the two being quite isolated from the remaining 
islands. The following table (p. 318) of the families, genera, 
and species of these molluscs will serve to illustrate the 
preceding observations. 

LInsects—Owing to the researches of the Rev. T. 
Blackburn and Mr. R. C. L. Perkins, we have now a fair 
knowledge of the Entomology of these islands. Unfortun- 
ately several of the orders have not yet been completely 


318 ISLAND LIFE PART II 


studied. ‘This is the case even with the Coleoptera, which 
apparently amount to about 1,000 species, and are as 
usual the most important order: the study of the Carabide 
and some other families is not yet completed, but the 


LAND AND FRESHWATER SHELLS OF THE SANDWICH ISLANDS. 


Number Species 
Families. of Species. known 
Genera. elsewhere. 

iL, daimacides: ist 2 7 2 All the - slugs 
closely allied to for- 
eign species. Per- 
haps all introduced 
by man, and modi- 
fied. 

DB. HOMME 2.5.5 252002 7 25 0 One genus, God- 
winia, peculiar. 

3. Philomycide ...... i! 2 2 

4. Endodontide ...... 2 24 0 One genus, Ptero- 
discus, peculiar. 

ie. SHOMCIOR 30) Ss k ens 2 2 i One widespread, 
(?)introduced. One 
doubtful. 

A Sc GP a ee 1 10 1 

7. ACHATINELLIDAZ .. 9 332 0 A peculiar family! 

8. Tornatellinide .... 1 14 1 One species in 
Tonga Island. 

9. Stenogyride ....... 2 4 2 Both perhaps in- 
troduced. 

10. Succineide ......... 1 27 0 
Li Dalaeia .f..5<. 3 13 0 
12. Melaniide ......... 1 6 0 
13. Paludestrinide ... 1 1 0 
14, Helicinide ......... 1 5 0 
15.- Neritidee ............ 1 5 0 
Totals 355.6022: 35 477 9 Five of these per- 
haps introduced. 


following numbers are approximately correct. About 900 
of the 1,000 species are apparently peculiar to the islands. 
About 200 are Carabide, 60 Staphylinide, 60 Nitidulide, 
100 Ptinidee, 42 Ciodide, 137 Aglycyderide (or Proterhinidze 


- 


CHAP. XV THE SANDWICH ISLANDS 319 


_--——— 


——- 


if the two families are distinct), 122 Curculionide, and 54 
Cerambycide. The remaining 200 species, or so, being 


distributed amongst about 25 other families. Many import- 


ant families, such as Cicindelidee, Scarabceidee, Buprestide, 
are either entirely absent or represented by one or two 
introduced species. ‘The absence of Chrysomelide, which 
usually form a large part of every Coleopterous fauna, is 
most noteworthy. In the eight families mentioned above 
most of the species belong to peculiar (precinctive) genera 
which usually contain numerous distinct species. 

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, 
and who has kindly furnished me with the latest facts and 
figures for the present edition of my work, says they are 
“mostly small or very minute 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 un- 
common 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 sunlight and 
luxuriant vegetation of the tropics. The facts become quite 
intelligible, however, if we consider that only minute 
insects of certain groups could ever reach the islands by 


1 ** Memoirs on the Coleoptera of the Hawaiian Islands.” By the Rev. T. 
Blackburn, B.A., and Dr. D. Sharp. Scientific Transactions of the Royal 
Dublin Society, Vol. III. Series II. 1885. See also Fauna Hawatiensis, 
Vol. II. part 3, 1900. 


x 


320 ISLAND LIFE PART II 
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. The 
most remarkable element in the Entomology appears to 
be the family Proterhinide. This is allied to Aglycyderide 
(of which only two species are known, one in New Zealand 
the other in the Canary Islands). It is not allied to any 
other Coleoptera, but apparently to some extent connects 
the clavicorn Coleoptera with the Rhynchophora. 137 
species of Proterhinide are known, all placed in one genus, 
Proterhinus. Although there is much variety in the genus, 
Mr. Perkins considers it cannot be satisfactorily divided. 
A few remarks on each of the more important of the families 
will serve to indicate their probable mode and period of 
introduction into the islands. 
The Carabide consists chiefly of seven peculiar genera of 
Anchomenini comprising fifty-one species, and several 
endemic species of Bembidine. Théy 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 Carabidee are found 
in the Azores, Canaries, and St. Helena, indicating that 
they possess some special facilities for transmission across 
wide oceans and for establishing themselves upon oceanic 
islands. The Staphylinidz present may peculiar species 
of known genera. Being still more minute and usually 
more ubiquitous than the Carabide, there is no difficulty in 
accounting for their presence in the islands by the same 
means of dispersal. The Nitidulide, Ptinidee, and Ciodide 
being very small and of varied habits, either the perfect 
insects, their eggs or larve, may have been introduced 
either by water or wind carriage, or through the agency of 
birds. Many of the Curculionids, being wood bark or nut 
borers, would have considerable facilities for transmission 
by floating timber, fruits, or nuts ; and the eggs or larvee of 


* See Hildebrand’s Flora of the Hawaiian Islands, Introduction, 
fi. ‘ 


CHAP. XV THE SANDWICH JSLANDS 321 


the peculiar Cerambycide could have been introduced by 
the same means. ‘The absence of so many important and 
cosmopolitan groups whose size or constitution render them 
incapable of being thus transmitted over the sea, as well 
as of many which seem equally well adapted as_ those 
which are found in the islands, indicate how rare have been 
the conditions for successful immigration ; and this 1s still 
further emphasised 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 Sandwich Islands.—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 their extreme isolation, their uniform 
volcanic soil, and the large proportion of the chief island 
which consists of barren lava-fields, the flor 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 (439 
Phanerogams and 39 ferns), which though less extensive 
are perhaps better known, or than the Galapagos (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 well explored, has less than twice as many flowering 
plants (1430 species), and Mr. W. B. Hemsley thinks that 
this number is probably too high. 

1 Flora of the Hawaiian Islands, by W. Hildebrand, M.D., annotated 
and published after the author’s death by W. F. Hildebrand, 1888. . 
b 


ISLAND LIFE PART II 
oe Ee Se 

The followmg list gives the number of indigenous 
species in each natural order. 


Number of Species in each Natural Order in the Hawaiian Flora, 
excluding the introduced Plants. 


322 


DICOTYLEDONS. 48. Gentianacee (Erythrea) ... 1 
1.) Remunculaces esi. sns.< vances 2 | 49. Loganiaces .:.....:.1.. cha 7 
2. Menispermacere 5.20.5 ..6.6645 4 | 50. Apocynacese:../.......22/ ae 
B,, F APAVOrsCew fo. .'ofic5, anes ci de 1 | 51. Hydrophyllacee (Nama— 
Ae OUIORES <a nk coated tcavaye S allies Andes) | ....,.s2s0aee 1 
5, Capperdaces oo. .25.tasde veces 2} D2, “Oleageeee oii cv: sets. hota 1 
G Vaelneee Ml) ow boots casey 8 | (53. Solanacem ‘..:.....0..4..00e 12 
i) Woe Ui octane, xt 7.” 2.| 54. Convolyulacess ..... i200 14 
8. Pittosporacer’ :.. 22 .68sd ois, 10.| 55. Boraginaces”’ :..... ..ceeee 3 
UY. ‘Caryophy ace nics cs fotcus- 23 | 56. Serophulariaces: ..........008 2 
tO: \Wrartulaorss 6 ts ees 3.1 57. Gesneriacess -);... 5-25 eee 24 
LAE BES oe alee Re cee 1 | 58. Myoporacez..::...:. 4.0 1 
12. Ternstreemiacee ............... 1 |: 59... Verbenaces ..<:...2.4...4. 1 
gE ES 2 ane Ce a ge 14. )-60. Labiate” 2.» le 39 
14: Peereuliacers. -65055-4 seek 2 | 61. -Plantaginacess + :...4...2 20 2 
RGR Sere oo: Pe Re a a 2 1 ||: 62. Nyetapinacese :y; ....c¢. ene 5 
1G; Geraniaces ....%.). 0.3%... -6 1°63. Amearantaces: .<......24. Ppp? 9 
17. Zygophylaces...-..:.,22.260++. 1..| 64. Phytolaceaces:....:<.2.... <0ee 1 
ie: Oxalidaces i....607..4 2250.24 1 | 65, -Polygonaces. ...2)2/0.eaee 3 
DIRE GIE oi hist tve chia. tay es 30 | 66. Chenopodiacesee ............... 2 
fa Np STG Race 1. 1.67.) eauraces: 22344... oe Lee 2 
DE MCIRBUTACCD 55. -/s2cd- sagan es 1.1 68. ‘Thymeleacess ...).......:..5 ae 7 
as, Henan CG 22. fhcy ti cendsc asses ’ | 69. Santelaces ........:.-.).ce 5 
2A. APN AACER o..2 52 eke td yeas 6.4.70. ‘Loranthaces |»... ..u.ceee | 
G4, AMacardiaces 566.0... his 5 1 | 71. Kuphorbiacem ..2).... 142 12 
2, MS PMMIMORR. «5 sve eaks arg yA Me ea) Of cr Sct: ee en EO 15 
BG AORAOOD rt he ownc alates on, 6) 73. Piperaces.....2.50../23 aoe 20 
27. Saxifragaces (trees) ......... 2 
a: \d Woserateds «0252 cdc, acon bus 1 MoNOCOTYLEDONS. 
AVG MOTABEIES, - o. S2 pec ssn co'yeice or mp 1) 74... Orchidaces itn eee 3 
SOS Mvruacers 6.7 heist ty. 6 | 75. Settamimaces: ...!.i./...5000 4 
Bl, digress... Gin ers 1 4 2Ge Avidaess j.5.00.024 {ccs ee 1 
B2: nm etatery testes ew cack Ack dt 1 4,. LACCACER 5 oe) ke ieee ee 1 
Do. MAcUeUt DEEaCORe » 2s oec ck ate sas 8 | 78. Dioscoreaces” «......ic.k.ceee 2 
BA ICOIGC ES Set ct eth eas catete ¥ 5 1 +79... Taliaeess: | 0.30. ee 7 
GS. Bevaniackee 2 i fare se. gloss ne: 1 | 80, Commelinaces).;.:.......-:220m 1 
SUL Om eer ees. eee s ssnans of 5 | 81. Flagellariaces .....:... 2... 1 
Ts APR IAROED, (2s ice sec ebuehs hee 12) 2. SxmCaeee iL. 0 secabe 1 
Be; MiUbeCees ost. ise eee eas 49 | 83. Palmacep... (oisi0a. ieee 3 
Bel Aa nosites os dies Ge ae 10 1.84. Pandanaces :.....6:0.c.. cee 2 
AG, pTaeheladeet: ok. speccuenesness 58) 1 SD. Avneee oeiscces<ss'ot ue 2 
41 AQGOUCMIaCRS. 46. 5. binees tegu 8 1-86. Naiadacer ......) >. «ruse 4 
42." WN decinceas ! i it.. lati ce hake 24 87. Uyperacess! cs. ...62. 2) Ree 47 
AS. WOPACTIGR COR) 6. 25 is kevin ghes svi 2 | 88. Graminacee........... ees. 57 
44, Bapotacewe wee icciecacssssen- ses 3 
45. Miyrsumnees osc... Ticc acts 5 VASCULAR CRYPTOGAMS. 
46. Primulacee  (Lysimachia) WOTWS. i eis bighes Ooh ee 136 
lari ie Bae hgaet S65 ace iets 6 Lycopodiacesz. ............... 17 
44. Phumbaginacess 2003.52.50. .0. 1 Rhizocarpes ..:....4/-aseee 2 


CHAP. XV THE SANDWICH ISLANDS 323 


Peculiar Features of the Flora.—This rich insular flora is 
wonderfully peculiar, for if we deduct 115 species, which 
are believed to have been introduced by man, there 
remain 705 species of flowering plants of which 574, 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 of Lobe- 
hhaceze is a tree reaching a height of forty feet. Shrubby 
geraniums grow twelve or fifteen feet high, and some 
vacciniums grow as epiphytes on the trunks of trees. 
Violets and plantains also form tall shrubby plants, and 
there are many strange arborescent composite, as in other 
oceanic islands. 

The affinities of the flora generally are very wide. 
Although there are many Polynesian groups, yet Austra- 
lian, New Zealand, and American forms are equally re- 
presented. Dr. Pickering notes the total absence of a large 
number of families found in Southern Polynesia, such as 
Dilleniacese, Anonacez, Olacacez, Aurantiaces, Guttiferee. 
Malpighiaceze, Meliaceze, Combretaceze, Rhizophoracez, 
Melastomacez, Passifloraceze, Cunoniaces, Jasminacez, 
Acanthaceze, Myristicacez, and Casuaraces, as well as the 
genera Clerodendron, Ficus, and epidendric orchids. 
Australian affinities are shown by the genera Exocarpus, 
Cyathodes, Melicope, Pittosporum, and by a phyllodinous 
Acacia. New Zealand is represented by Ascarina, 
Coprosma, Aczena, and several Cyperaceze ; while America is 
represented by the genera Nama, Gunnera, Phyllostegia, 
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, Silene, 
Gnaphalium and Geranium, as occurring above ten 


324 ISLAND LIFE PART II 


thousand feet elevation ; while Viola, Drosera, Aczena, 
Lobelia, Edwardsia, Dodonza, Lycopodium, and many 
Composite, range above six thousand feet. Vaccinium 
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. Composite......./0% 70 species.) 12,, Uriteacer: 2/2. .oy: 15 species. 
2. Lobeliatez..:.:....<.. See 13; Malverne 2.7.) 0-2 14 
S, Graminaces '..;:5..5. 3 ie Ba 14. Convolvulacee ...... 14) 
A TRATIRCERE. hes csi ee oe 15, .Arabiacete: oecciin ak 122 Se 
Dy) MOV ORARCIE 4522 As a ae 10, SOlgmaCete 4... 22 seat. 12 
Oe Diana reso) aad. oo) 17 EKuphorbiacee ...... 120 
Tuba: esis. | ee 18. Pittosporacee ...... LO tee 
8. Gesneriacez ......... 7; 19. Amarantacee......... eee 
9. Caryophyllacez ..... De it = ys 20." Violaceds- sig i.) cats .: eae 
10. Leguminose ......... BAT rs, 21. Goodeniacee ......... ae aa 
Pe Piperack .2.'.0..05 345 BOY 555 


Nine other orders, Geraniacez, Rhamnacez, Rosacez, 
Myrtacez, Primulacez, Loganiacez, Liliacez, Thymelacee, 
and Cucurbitacez, have six or seven species each; and 
among the more important orders which have less than 
five species each are Ranunculacez, Cruciferz, Vaccinacez, 
Apocynaceze, Boraginacee, Scrophulariaceze, Polygonacee, 
Orchidacez, and Juncaceze. The most remarkable feature 
here is the great abundance of Lobeliacez, a character of 
the flora which is probably unique ; while the superiority 
of Labiatz to Leguminose and the scarcity of Rosacez 
and Orchidacez 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 Composite 
in the islands. Sixty-one of the species are peculiar, as 
are eight of the genera; while the genus Lipocheta with 
eleven species is only known elsewhere in the Galapagos, 
where a single species occurs. We may therefore consider 
that nine out of the nineteen genera of Hawaiian Com- 


CHAP. XV THE SANDWICH ISLANDS 325 
posite are really confined to the Archipelago. The rela- 
tions of the peculiar genera and species are indicated in 
the following table.? 


Affinities of Hawaiian Composites. 
No. of 


Peculiar Genera. Species. External Affinities of the Genus. 

a 2 Very peculiar. Allied to the North American 
| genus Grindelia. 

Tetramolobium... 7 South Temperate America and Australia. 
Lipocheta ......... 11 Allied to American genera. 

Campylotheca ... 12 With Tropical American species of Bidens and 

Coreopsis. 

Argyroxiphium... 2 With the Mexican Madiee. 

ekesla............ 2 Same affinities. 

Peanantia .:........ 6 With the Mexican Raillardella. 

Raillardia ......... 12 Same affinities. 


Hesperomannia... 2 Allied to Stifftia and Wunderlichia of Brazil. 


Peculiar Species. 


Lagenophora ...... 1 Australia, New Zealand, Antarctic America, Fiji 
Islands. 

PpemeciO ............ 2 Universally distributed. 

Mftemisia .......:. 2 North Temperate Regions. 


The great preponderance of American relations in the 
Compositz, as above indicated, is very interesting and 
suggestive, since the Composite of Tahiti and the other 
Pacific Islands are allied to Malaysian types. It is here 
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 of 
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 by 
wind and other means, we can hardly doubt that its origin 
dates back to a very remote epoch. We may therefore 
look upon the Composite as representing the most ancient 
portion of the existing flora of the Sandwich Islands, 
carrying us back to a very remote period when the facili- 
ties for communication with America were greater than 
they are now. This may be indicated by the two deep 
submarine banks in the North Pacific, between the Sand- 
wich Islands and San Francisco, which, from an ocean floor 


1 These are obtained from Hildebrand’s Flora supplemented by Mr. 
Bentham’s paper in the Journal of the Linnean Society. 


326 ISLAND LIFE PART II 


_—, 


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, when 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. i | 

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 Lobeliacez 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-peculiar 
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 established 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 habitats. The following is a list of the peculiar 
genera with the number of species in each. 


CHAP. XV 


THE SANDWICH ISLANDS 


327 


Peculiar. Hawaiian Genera of Flowering Plants. 
Genus. No. of Species. Natural Order. 
Me MMMNSIETORE lon joven scars ta qedectaeatscavaewehes 3 Violacce. 
2. Schiedea (seeds rugose or muricate) ......... 17 Caryophyllacee. 
REM PE ERE TOUR 55 502d is ny 6apabaevinwe vastede ras 1 rf 
er itd sel on sien wa sve ve aA MORY hoe ve 20 Rutaceze. 
IORI ti esa wot xo luis is nw dds ca ton Bede bauged 4 a 
MOG TA Bed) ccd ulenee eh cy usdiaduwet ees sar’ 1 Sapindacee. 
EET ee eee ee ee er oy or eee 2 Saxifragacee, 
Me EAM MOOTRTIGIAS 21 Jh., cos anc ach asevwisorservaerence tras 1 Begontacez. 
9. Cheirodendron (fleshy fruit)..................... 2 Araliacese, 
20. Pterotropia (succulent). 22.0... 05.00. -.0. <0! 3 Pa 
ered STADIAGMNGTS (OTUNGE) oon. te. ee ict a ees coeur 4 pe 
12. Kadua (small, flat, winged seeds) ............ 16 Rubiacee. 
RET SROMELCLUE (OE LY ) cc's uo once toss mee sacnsy ets noe tedden 5 fe 
ee SRN (A TUDS 515 oid octeefye neh tut vane ee sha 5 ‘3 
Me CAMBRIA, (OTUDO ) 6 oi. 56 ks coh doycxen dng ee s atone 5 9 
NER Soy cheese Satan this pat stinte sec eee 2 Composite. 
a Sit aN Ol PTI Ge. o 262.0. «as buc ees vee vac en adltes’ 7 a 
ES ny Dane Ren ane ee Pr te Bele eee 11 As 
OI MUTI AOUIIOCR 0505 Fo das sc ahaneinp ohohnw poe ecaven cee be ad 
PU LORTQIUIIN. 65 ois. s ce sccr ese cornsns shes sevens 2 7 
A RS a tT ania OS eRe Ao 2 oe 
8 US 2 Ee a ON ae Ge ee RON Re MRC ee 6 se 
OREM AIR P'S cy an sinusnedivenisdvabohse sonra: ly oe 
Me SPOMDUTOURADTIS oo. s a ee ge npn ae ccaes con esacee 2 i 
Reto ama 23. ae a 1 Lobeliaceze. 
mee memountia (berry): 5.200 )...0tse0vcnannte bce ..02k 11 ny 
EES SS ee me ea ee a ene es SR a 6 pe 
EE Ry Ae thas Oi Clete Nar Ree Pe BESS 7 Py 
0 Lo SUPE UR ge nee avon cts ae eee 28 9 
IRM Sr 05 hz) iy 12d ited Aha pawettin ae Le 9 Loganiacee. 
Mee SVOUNOCEBETUIM § «.. .<..ic.. so. tas Se aetna 4 Solanacez. 
32. Haplostachys (nucules dry)..................... 3 Labiate. 
33. Phyllostegia (nucules fleshy) .................. 16 ws 
34. Stenogyne (nucules fleshy) ..................... 16 #5 
STAT 1 Rae ee Re 3 Amarantacez. 
PET IOES oo acne ne cov ccs senna cane aids seeass 2 ve 
Sr near aia, 850A. al ee 1 Urticacez. 
RIED irs, he le Ok | A Sahiba oa wtenodee 2 zs 
ORAL Sh os tieea vcmated sak 254 species. 


The great preponderance of the two orders Composite 


and Lobeliacez are what first strike us in this list. 


In the 


former case the facilities for wind-dispersal afforded by the 
structure of so many of the seeds render it compara- 
tively easy to account for their having reached the islands 
-at an early period. The Lobelias, judging from Hilde- 
brand’s descriptions, may have been transported in several 


328 ISLAND LIFE PART II 


different ways. Most of the endemic genera are berry- 
bearers and thus offer the means of dispersal by fruit- 
eating birds. The endemic species of the genus Lobelia 
have sometimes very minute seeds, which might be carried 
long distances by wind, while other species, especially 
Lobelia gaudichaudu, 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 orbicular, 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 present several endemic 
genera indications of the mode of transit to the islands 
are afforded us. The Araliaceze are said to have fleshy 
fruits or drupes more or less succulent. The Rubiaceze 
have usually berries or drupes, while one genus, Kadua, 
has “small, flat, winged seeds.” The two largest genera 
of the Labiatz are said to have “fleshy nucules,” which 
would no doubt be swallowed by birds. 

Antiquity of the Hawaunan Fauna and Flora.—The 
ereat 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 would soon occupy 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 which at a later 


1 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 Viola 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. Geraniwm arborewm is sometimes twelve feet 
high. The endemic Composite are mostly shrubs, while several are trees 
reaching twenty or thirty feet in height. The numerous Lobeliacez, 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 Primulacee—Lysimachia—consists mainly of shrubs ; and even a 
plantain has a woody stem sometimes six feet high. . 


CHAP. XV THE SANDWICH ISLANDS 329 


period spread over Polynesia. The extreme remoteness 
of the islands, and. the probability that they have always 
been more isolated than those of the Central Pacific, 
would also necessarily result In an imperfect and 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 
greater facilities for dispersal than animals, and also having 
greater 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, and the same is the case with the birds; 
while other members of the animal world, passing across 
the sea with greater difficulty and subject to extermination 
by a variety of adverse conditions, retain more of the im- 
press of a recent state of things, with here and _ there, 
especially i the birds, an indication of that ancient 
communication with America so clearly shown in the Com- 
positze and some other portions of the flora. 


GENERAL REMARKS ON 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, while their reptiles, when they possess 
any, do not exhibit indications of extreme isolation and 
antiquity. Their birds and insects present just that 
amount of specialisation and diversity from continental 
forms which may be well explained by the known means 
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 
primeval 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 presents 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 important to note that none of these 
oceanic archipelagoes present us with a single type which 
we may suppose 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 occupied 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 exeepuod 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 XVI 


CONTINENTAL ISLANDS OF RECENT ORIGIN : GREAT 
BRITAIN : 


Characteristic Features of Recent Continental Islands—Recent Physical 
Changes of the British Isles—Proofs of Former Elevation—Submerged 
Forests—Buried River Channels—Time of Last Union with the Conti- 
nent—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 Freshwater Shells 
—Peculiarities of the British Flora—Peculiarities of the Irish Flora— 
Peculiar British Mosses and Hepatice—Concluding Remarks on the 
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 period 
which, geologically, must be considered recent. Such 
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 of 
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, differ from each 


332 ISLAND LIFE PART II 


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 or almost wholly contained in the 
separated portion or island, to which it will henceforth be 
peculiar, Kven 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 which 
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 outline 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. 

Recent Physical Changes wm 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 the 


CHAP. 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. (See Map.) 


=f SHETEAND 


= 
———aee 
es 


=p—* 
—— — 


= 
=a 


HOKLAND 
\ 


PS 


MAP SHOWING THE SIIALLOW BANK CONNECTING THE BRITISH ISLES WITH THE CONTINENT. 


The light tint indicates a depth of less than 100 fathoms. 
The figures show the depth in fathoms. 
The narrow channel between Norway and Denmark is 2,580 feet deep. 


Beyond this line the sea deepens rapidly to the 500 and 
1,000 fathom lines, the distance between 100 and 1,000 


834 ISLAND LIFE PART II 


fathoms being from twenty to fifty miles, except where 
there is a great outward curve to include the Porcupine 
Bank 170 miles west of Galway, and to the north-west of 
Caithness where a narrow ridge less than 500 fathoms 
below the surface jos the extensive bank under 300 
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 Former Hlevation—Submerged Forests.—W hat 
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 the late 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 335 


“We were so fortunate as to reach the beach at spring- 
tide low-water, and to find, admirably exposed, by far the 
finest example of a submerged forest which I have 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 brownish drab-coloured clay, which 
was crowded with vegetable débris, such as small twigs, 
leaves, and nuts. There were 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 wood was found to have a reddish 
or bright pink hue, when fresh surfaces were exposed. 
Some of it, as well as many of the twigs, had almost 
become a sort of ligneous pulp, while other examples were 
firm, and gave a sharp crackling sound on being broken. 
Several large stumps projected above the clay in a vertical 
direction, and sent roots and rootlets into the soil in all 
directions and to considerable distances. It was obvious 
that the movement by which the submergence was 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 was not above the level of high water. There is 
satisfactory evidence that in Torbay it was not less than 
forty feet, and that in Falmouth Harbour it amounted to 
at least sixty-seven feet.” ! 


1 Geological Magazire, 1870, p. 155. . 


836 | ISLAND LIFE PART tt 


On the coast of the Bristol 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 hyeenas; facts which can only be explained by 
the existence of some extent of dry land stretching sea- 
ward from the present cliffs, but smce 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. 

Buried 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- 

1 Transactions of the Edinburgh Geological Society, Vol. I. p. 380. 


CHAP. XvI THE BRITISH ISLES 337 


mouth the old channel is 260 feet below the sea-level 
The watershed at Kilsith is now 160 feet above the sea, 
the old valley bottom being 120 feet deep or forty feet 
above the sea. In some places the 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 these rivers 
were formed, the land must have stood in relation to the 
sea at least 260 feet higher than it does now, and probably 
much more; and this is sufficient to jom 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 (Unio prctorum) off the mouth of the English 
Channel between the fifty fathom and 100 fathom lines, 
while in the same locality gravel banks with littoral shells 
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 water, all being characteristic 
shallow water species, so that their association at this 
great depth is a distinct indication of considerable sub- 
sidence.” 

Time of Last Union with the Continent—The period 
when this last union with the continent took place was 
comparatively recent, as shown by the identity of the 
shells with living species, and the fact that the buried 
river channels are all covered with clays and gravels of 
the glacial period, of such a character as to indicate that 
most of them were deposited above the sea-level. From 
these and various other indications geologists are all 
agreed that the last continental period, as it is called, was 
subsequent to the greatest development of the ice, but 
probably before the cold epoch had wholly passed away. 
But if so recent, we should naturally expect our land still 

1 Quarterly Journal of Geological Society, 1850, p. 96. 
2 British Association Report, Dundee, 1867, p. 431. 
Z 2 


308 ISLAND LIFE PART II 


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 in adaptation to these conditions 
resulting in a local race, sub-species, or species. 

Why Britain 1s Poor i 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 Kurope. 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. 


OHAP. XVI THE BRITISH ISLES 339 


To this cause we must impute our comparative poverty 
in mammalia and reptiles—more marked in the latter 
than the former, owing to their lower vital activity and 
smaller powers of dispersal. Germany, for example, 
possesses nearly ninety species of land mammalia, 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 the 
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 amphibia. 
Britain ” 13 9 9 9 
Ireland 99 4 99 a2 oa 


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 passing 
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. 

Peculiar British Birds—Among 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 Hurope 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 


340 ISLAND LIFE PART II 


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 winter 
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 :— 


1. Parus ater, sub. sp. BRITANNICUS...... Closely allied to P. ater of the 
continent; a local race or 
sub-species. 

2. Acredula caudata, swb. sp. ROSEA ...... Allied to A. caudata of the 
continent. 

3. LAGOPUG. SUOTICUBY .iisbeecetingsns dete ses Allied to Z. albus of Scandin- 
avia, a distinct species. 

4. Troglodytes parvulus var. HORTENSIS.St. Kilda, Hebrides. 


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 


CHAP. XVI THE BRITISH ISLES 341 


confined to single lakes, often of small area, and these latter 
offer examples of the most restricted distribution of any 
organisms whatever. Cases of this kind are found in our 
own islands, and deserve our especial attention. It has 
long been known that 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. Giinther obtained numerous 
specimens from every part of the country, and by com- 
parison with all known continental species determined 
their specific differences. The striking and unexpected 
result has thus been attained, that no less than fourteen 
well-marked species of freshwater fishes are altogether 
peculiar to the British Islands. The following is the list, 
with their English names and localities :—* 


Freshwaler Fishes peculiar to the British Isles. 


Latin Name. English Name. Locality. 
1. SALMO BRACHYPOMA | Short-headed salmon | Firth of Forth, Tweed, 
Ouse. 
2. 4,  ORCADENSIS.. | Loch Stennis trout... | Lakes of Orkney. 
mies. FPEROX..).. i: Great lake trout...... Larger lakes of Scotland, 


Ireland, the N. of 
England, and Wales. 


a. ,, #STOMACHICUS | Gillaroo trout ......... Lakes of Ireland. 

5. 4,  NIGRIPINNIS. | Black-finned trout ... | Mountain lochs of Wales 
and Scotland. 

6. ,,  LEVENENSIS. | Loch Leven trout ...| och Leven, Loch Lo- 
mond, Windermere. 

eee.) PERISH wis: Welsh icharr.. (03.4.2 Llanberis _ lake, N. 
Wales. 

8. 


»,  WItLLuGHBII | Windermere charr ...|Lake Windermere and 
others in N. of Eng- 
land, and Lake Brui- 
ach in Scotland. 


9. ,,  KILLINENSIS | Loch Killin charr.... | Loch Killin in Inverness- 
shire. 

eee, \COLIT ......5. Cole's eharr.i.. 54:26 Lough Eske and Lough 
Dan, Ireland. 

RES 2 ¢ Gray's chalr:........- Lough Melvin, Leitrim, 


N.W. Ireland. 


1 The list of names was furnished to me by Dr. Giinther, and I have 
added the localities from the papers containing the criginal descriptions, 
and from Dr. Houghton’s Lritish Freshwater Fishes. The most recent 
corrections have been made by Mr. James R. Hill of Keswick, and by 
Dr. Giinther. 


342 ISLAND LIFE PART Il 


Latin Name. English Name. Locality. 


12. CoREGONUS cCLUrE-|The gwyniad, or;I.och Lomond,  Ulles- 
o1pes | - schelly .2427h.cnne water, | Haweswater, 
Red Tarn (Helvellyn), 
Conningham mere 
(Lancashire), Pemble 
mere, near Chester, 
and Bala lake. 


be: 43 VANDESIUS | The vendace .......... Loch Maben, Dumfries- 
shire, Derwentwater, 
and Bassenthwaite — 
lake. 

14. ts POLLAN ...| The pollan v.42. 0.) Lough Neagh and Lough 


Earne, N. of Ireland. 


These fourteen 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. Aillinensis 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, which has no less than four species 
altogether peculiar to it. If the species of our own two 
islands are thus distinct, what 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 possess of the very restricted ranges of many of 
our species, we must certainly hold them to be peculiar 
till they have been proved to be otherwise. | 

The great speciality of the Irish fishes is very interesting, 
because 1t 1s 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 


CHAP. XVI_ THE BRITISH ISLES 343 


Ireland ; and the latter country has been longer isolated, for 
the Irish Sea with its northern and southern channels is 
considerably deeper than the German Ocean and the 
Eastern half of the 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 produced 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 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 tothe Llanberis lakes, about 
three miles in length; Gray’s charr confined to Lough Mel- 
vin, about seven miles long; and the Loch Killin charr, 
known only from a small mountain lake in Inverness-shire. 

Cause of Great Speciality in Fishes—The reason why 
fishes alone should exhibit such remarkable local modifica- 
tions in lakes and islands is sufficiently 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 where 
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 bring 
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, because 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 the British and Irish lakes, 


344 ISLAND LIFE PART II 


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 Roads of Glenroy, and it probably affords the true 
solution of many of the cases in which existing species of 
fish inhabit distinct river basins whether in streams or 
lakes. Ifa 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 difficult 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 yearly 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. XVI THE BRITISH ISLES 345 
years Britain is its only recorded locality; but at length it 
is found on some part of the continent, and not unfrequently 
has been all the time known there, but disguised by another 
name, or by being classed as a variety of some other 
species. This has occurred so often that our best entomo- 
logists have come to take it for granted that all our 
supposed peculiar British species are really natives of the 
continent and will one day be found there; and owing 
to this belief 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 
has been held by such well-known authorities as the late 
Mr. EK. 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 are 
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 part 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 doing that we can hope to 
arrive at any correct solution of the question on which there 
is at present so much difference of opinion. For the list 
of Coleoptera with the accompanying notes I was 
originally indebted to the late Mr. E. 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. 


| Lepidoptera. 
Among the Lepidoptera the probability of there being 


peculiar British forms is still greater, owing to the fact 
that the larve of many of them feed during winter. 
This is the case with some of our peculiar species of 
Tineina, a habit which they are able to adopt in our mild , 
insular climate, but which is usually impossible when 
exposed to the severer continental winter. A curious 
example of the effect this habit may have on distribution 
is afforded by one of our commonest British species, 
Elachista rufocinerea, the larva of which mines in the leaves 
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. . 
In the first edition of this work the list of supposed 
peculiar British species was revised by the late Mr. H. T. 
Stainton, and that in the second edition was corrected by: 


CHAP. XVI THE BRITISH ISLES 346a 


Messrs. Warren and Barrett and Lord Walsingham, and 
the two former gentlemen have kindly given me further 
corrections for the present issue. But I am now especially 
indebted to Mr. J. W. Tutt, editor of the Hntomologist’s 
Record and author of a standard work on the Noctuide. 
He has furnished me with a list of no less than four 
hundred species, varieties, and aberrations of British 
Lepidoptera, which are, so far as known, peculiar to our 
islands. The latter term applies to more than half the 
forms cat#togued, and indicates a slight sport, abnor- 
mality, or variation, that occurs sporadically, but does not 
form a local race or established variety. I have therefore 
omitted all these aberrations from the following list of the 
Species and Varieties of endemic British Lepidoptera, and 
I do so with the less regret as Mr. Tutt proposes to give 
the entire catalogue in his fecord. : 

Mr. McLachlan has kindly furnished me with some 
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, are confined to the British Islands. 
DIvuRNI. 


1. CHRYSOPHANUS DISPAR, Haw. Formerly locally abundant in the 
Fens of Cambridgeshire and Huntingdonshire, but now extinct. 
It is a large, brightly coloured race of a widely distributed species 
known as C. rutilus on the Continent. The specimens from 
Bordeaux and the Pontine marshes closely approach the British 
form. But on the whole the British race seems to be distinct and 
characteristic. 

. Polyommatus astrarche, var. ARTAXERXES, Fab. A local race almost 
entirely confined to Scotland. 

. Melitea aurinia, var. PRECLARA, Kane. Chiefly confined to Ireland. 

. M. aurinia, var. scoTica, Tutt. Confined to Scotland. 

. Coenonympha typhon, var. scorica, Staud. Scotland and Ireland. 


OUP co bo 


ARCTIIDES. 


. Lithosia complana, var. SERICEA, Gregson (1861). Lancashire. 
. Svilosoma menthastri, var. scoTiIcA, White. Scotland. 


“IO 


346) ISLAND LIFE PART II 


NOocTUIDES. 


8. Apatela aceris, var. INTERMEDIA, Tutt. A British form more 
ochreous than the Continental type. 

9. Triena psi, var. BIDENS, Chapman. Hereford. 

10. Pharetra menyanthidis, var. scoTicaA, Tutt. Western Scotland. 

11. Arctomyscis euphorbie, va7. MyRIC#, Guen. (1852). Scotland and 
Ireland. 

12. LEUCANIA FAVICOLOR, Barrett. Essex. Near LZ. pallens, perhaps 
a distinct species. | 

13. TAPINOSTOLA CONCOLOR, Guen. A local species, quite distinct. 
Confined to Cambridge, Hunts, and Essex. 

14. HypRa@cIA PALUDIS, Tutt. A very distinct species’ Coast dis- 
tricts of south-east of England. 

15. Miana bicoloria, var. RUFUNCULA, Haw. Norfolk, Howth. 

16. Celena haworthii, var, HIBERNICA, St. Chiefly in Ireland. 

17. a cea difflua (maillardi), va7, AsstMILIs, Dbldy. Scotch High- 
lands. 

18. Aporophyla australis, var, PASCUEA, Curt. (1830). British form. 

19. Luperina luteago, vav. BARRETTII, Dbldy. (1864). Ireland, Cornwall, 
S. Wales. 

20. Agrotis obelisca, var. GRISEA, Tutt. I. of Wight. 

21. A. tritici, var. soRDIDA, Haw. 


22. a ,5 PUPILLATUS, Haw. 

23. B, » OCHRACEA, Tuit. 

24. ae »,  VALLIGERA, Haw. These forms of a very vari- 
25. S », CUNEIGERA, Stephs. able species have not yet 
26. a », ALBILINEA, Haw. been recorded from the 
27. . ,, LINEOLATA, Haw. Continent. 

28. i. 5, VENOSA, Stephs. 

29. ss ,» HORTORUM, Stephs. 

30. COSTANIGRA, Tutt. 


al. Ay agathina, var. HEBRIDICOLA, Staud. Hebrides. 

32. A. SUBROSEA, Stephs. (1835). ‘A peculiar British fenland form, now 
probably extinct, of a wide-spread Continental species. 

33. A. lucernea, var. RENIGERA, Stephs. N. Britain. 

34. Lycophotia strigula, var. suFFUSA, Tutt. Shetlands. 

35. Noctua glareosa, var. SUFFUSA, Tutt (EDDA, Staud.). Scotland and 
Hebrides. 

36. N. dablii, var. RUFA, Tutt. Scotland and Ireland. 

of.. N; primule, var. THULEI, Staud. Hebrides and Iceland. 

88. Pachnobia hyperborea, var. ALPINA, Humph. Scotland. 

39. P. rubricosa, vav. RUFA, Tutt. Southern counties. 

40. Teniocampa incerta, var. CHRULESCENS, Tutt. England only. 

41. T. gracilis, var. RUFESCENS, Ckll. Hants and Kent. 

42. Anchocelis litura, var. RUFA, Tutt. South of England. 

43. Hoporina croceago, var, LATERITIA, Raynor. 

44, Tiliacea citrago, var. AURANTIA, Tutt. 

45. Calymnia trapezina, var. RUFA, Tutt. 

46. Dianthcecia carpophaga, var. PALLIDA, Tutt. Chalk districts. 

47. D. conspersa, var. OCHREA, Gregson. ’ Orkneys and Cornwall. 

48. 9 var. OBLITER#, Robson. Shetlands. 

49, D. cesia, var. MANANI, Gregson. I. of Man and Ireland. 


GHAP. XVI THE BRITISH ISLES 846¢ 


50. 
51. 
52. 
53. 
54. 


55. 
56. 
57. 
58. 
59. 
60. 
61. 
62. 
63. 
64. 
65. 


66. 


Polia chi, var. OLIVACEA, Stephs. N. England and S. Scotland. 
P. chi, var. SUFFUSA, Robson. Yorkshire. 
5» var. NIGRESCENS, Tutt. Yorkshire. 
P. xanthomista, var. STATICES, Gregson. Cornwall, I. of Man. 
Cleoceris viminalis, var. OBSCURA, Stdgr. (UNICOLOR, Tutt). N. of 
England. 
Epunda lutulenta, var. ALBIDILINEA, Tutt. Orkney Islands. 
Bryophila muralis, var. IMpAR, Warren. Cambridge. 
Aplecta nebulosa, var. PALLIDA, Tutt. Glasgow. 
A. advena, var. UNICOLOR, Tutt. 
Hadena protea, var, VARIEGATA, Tutt. 
H. pisi, var. scoTica, Tutt. North of England, Ireland and Scotland. 
Xylina furcifera, var. suFFUSA, Tutt. Wales. 
X. socia, var’. RUFESCENS, Tutt. S.W. England, S. Ireland. 
Calocampa vetusta, var. SUFFUSA, Tutt. N. Britain. 
Lithomia solidaginis, var. surrusA, Tutt. Aberdeen. 
Anarta myrtilli, var. RUFESCENS, Tutt. §S. England. 


NOTODONTIDES. 


Notodonta dromedarius, var. PERFUSCA, Stphs. N. of England, 
Scotland. 
No.ipEs. 


. Nola cucullatella, var. FULIGINALIS, Stephs. London district. 
. N. strigula, var. MONACHALIS, Haw. 


CYMATOPHORIDES. 


. Cymatophora or, var. scotica, Tutt. Scotland. 
. C. duplaris, var. ARGENTEA, Tutt. Ireland, &c. 


var. OBSCURA, Tutt. N. England, Scotland. 


: Asphalia flavicornis, var. GALBANUS, Tutt. 8S. England. 


GEOMETRIDES. 


. Zonosoma annulata, var. OBSOLETA, Riding. Devonshire. 

. Lygris testata, var. INSULICOLA, Staud. Shetlands, Hebrides. 

. Melanthia bicolorata, var, PLUMBATA, Curt. N. England, Scotland. 
. Melanippe fluctuata, var. THULES, Prout. Shetlands. 

. M. montanata, var. SHETLANDICA, Weir. Shetlands. 

. M. sociata, var. OBSCURATA, South. Hebrides and Iceland. 

. Larentia autumnata, var. FILIGRAMMARIA, H.S. WN. England, 


Scotland, and Ireland. 


. L. flavicinctata, var. OBSCURATA, Staud. Scotland. 
. Camptogramma bilineata, var. ATLANTICA, Staud. Shetlands and 


Hebrides. 


. C. bilineata, var. IsoLATA, Kane. Islet off Kerry. 
. Eupithecia pulchellata, var. HEBUDIUM, Sheldon. Hebrides. 


. E. JASIONEATA, Crewe. Devonshire, Ireland, 


. E. satyrata, var. CALLUNARIA, Dbldy. 


. var. CURZONI, Gregson. Shetlands. 


. E. sobrinata, var. STEVENSATA, Webb. Dover. 
. E. rectangulata, var. NIGROSERICEATA, Liaw. London, &e. 


346d 


89. 


90. 


91. 
92 


93. 
94. 


95. 


96. 
97. 


98. 


99. 


100. 


101. 


102. 
103. 


104. 


105. 
106. 
107. 


108. 
109. 
110. 
itt; 
112: 


113. 


114. 
115. 
116. 
ove 


118. 


119. 


120. 
121. 
122. 
123. 
124. 
125. 


ISLAND LIFE PART II 


Emmelesia albulata, var. HEBUDIUM, Weir. Hebrides. 
s var. THULES, Weir. Shetlands. 
Hybernia marginaria, var. FUSCATA, Harrison. North England. 
Boarmia gemmaria, var. PERFUMARIA, Newman. London, Hudders- 
field, &c. 
B, repandata, var. NicRA, Tutt. Huddersfield. 
3 var. SODORENSIUM, Weir. Hebrides. 


PYRALIDES. 


Homcosoma nimbella, var. sAxXIcOoLA, Vaughan (1871). England, 
Scotland, Ireland. 

EPISCHNIA BANKESIELLA, Rehdson. (1888). Isle of Portland. 

Scoparia cembre, var. scoTIcA, White (1872). Scotland. 

S. ULMELLA, Knaggs. Northern counties. Distinct species. 

S. BASISTRIGALIS, Knaggs. A distinct species. Recorded from 
Germany, but with doubt. 

S. dubitalis, var. PURBECKENSIS, Bankes. Chalk cliffs of south 
coast. 

S. frequentella, var. PORTLANDICA, Dale. I. of Portland. 


GELECHIIDES. 


BRYOTROPHA POLITELLA, Sta. (1854). Doubtfully in S. France. 

LITA PLANTAGINELLA, Sta. Probably overlooked on Continent. 

L. SUZDELLA, Rchdsn. rt 

L. BLANDULELLA, Tutt. Deal sand-hills. 

L. VISCARIELLA, Sta. South coast. 

L. FRATERNELLA, Doug]. (1834). Recorded with doubt from Germany. 

XYSTOPHORA DIVISELLA, Dougl. (1856). A Fen insect; rare. 

ANACAMPSIS VINELLA, Bankes. | 

ARGYRITIS TARQUINIELLA, Sta. Perhaps a form of A. pictella. 

DEPRESSARIA AURANTIELLA, Tutt. Deal. 

BORKHAUSENIA WOODIELLA, Curtis. A well-marked species. Not 
found for many years. 


279 


TORTRICIDES. 


PERONEA CALEDONIANA, Stephens. Perhaps a moorland form of P. 
aspersand. 

P. schalleriana, var. PERPLEXANA, Barr. Ireland, England. 

ASTHENIA COGNATANA, Barrett. 

Caccecia musculana, var. MUSCULINANA, Kenn. Shetland. 

Cnephasia penziana, var. BELLANA, Curt. 

oe var. COLQUHOUNANA, Barrett. Ireland, West 

Scotland to Shetlands. , 

C. OCTOMACULANA, Curt. A distinct northern species. 

LozoPERA BEATRICELLA, Walsm. Suffolk. 

EVETRIA PINICOLANA, Dbldy. 

EUP@CILIA GRISEANA, Stphs. 

E. ERIGERANA, Walsm. South-east England. 

E. SUBROSEANA, Haworth. Recorded ? from Germany. 

E. FLAVICILIANA, Wilksn. 


CHAP. XVI THE BRITISH ISLES 347 


126. 
127, 
128. 
129. 
130. 
131. 
132. 


133. 


134. 
135. 
136. 
137. 
138. 


139. 
140. 


141. 


142. 
143. 
144. 
145. 
146. 


147. 
148. 
149. 
150. 
151. 
152. 
153. 
154. 
155. 
156. 
157. 
158. 
159. 
160. 


161. 


E. DEGREYANA, McLach. 

E. angustana, va7. THULEANA, Vaughan. Shetland Islands. 

CoNCHYLIS SUBBAUMANNIANA, Wilk. A distinct species. 

OLETHREUTES WOODIANA, Barrett. A fine species. Herefordshire. 

Penthina sauciana, var. STAINTONIANA, Barr. Scotland. 

Catoptria scopoliana, var. PARVULANA, Wilk. I. of Wight. 

PHOXOPTERYX SUBARCUANA, Douglas. Perhaps a form of. P. 
biarcuana. 

Bactra lanceolana, var. NIGROVITTANA, Stephns. Scotland. 


PSYCHIDES. 


FuMEA scoTica, Chapman. Rannoch, Sutherland. 
MASONIA HIBERNICELLA, Chapman. Ireland. 

M. MITFORDELLA, Chpmn. 

BANKESIA DOUGLASII, Stainton. Surrey. 

B. STAINTONI, Wlsm. Southampton. 


TINEIDES, 


ACROLEPIA MARCIDELLA, Curtis. 

A. BETULELLA, Curtis (1840). Yorkshireand Durham. Doubtfully 
from Germany. 

MEESIA RICHARDSONI, Walsm. — Dorset. 


ELACHISTIDES. 


CATAPLECTICA FARRENI, Walsm. Cambridge. 

ELACHISTA KILMUNELLA, Sta. N. England and Scotland. 

E. CONSORTELLA, Sta. (1854). Scotland. 

EK. scrrpi, Sta. Wales and Sussex. Salt marshes. 

E. ELEOCHARIELLA, Sta. Shetlands. Recorded, with doubt, from 
Hartz Mountains 


CoLEOPHORIDES. 


COLEOPHORA POTENTILLA, Elisha. S. of England. 
C. TRICOLOR, Walsm. 

C. SATURATELLA, Sta. (1850). 8S. of England 

C. INFLATA, Sta. 8. and E. England. 

C, TINCTORIELLA, Coverdale. 

C. SYLVATICELLA, Wood. 

C. GLAUCICOLELLA, Wood. 

C. AGRAMMELLA, Wood. Rush-feeding species. 

C. ADJUNCTELLA, Hodgkn. (1882). Lancashire, Essex. 
C. TRIPOLIELLA, Hodgkn. 

C. ARTEMISIELLA, Scott. 

C. SQUAMOSELLA, Sta. (1856). Surrey. 

C. SALINELLA, Sta. (1859). Sea coast. 
GONIODOMA LIMONIELLA, Sta. I. of Wight. 


LYONETIIDES. 


CEMIOSTOMA OROBI, Sta. 


348 ISLAND LIFE PART II 


LITHOCOLLETIDES. 


162. Lithocolletis lautella, var. IRRADIELLA, Scott (1854). Scotland. 
163. L. ANDERIDA, Fletcher (1886), Dorset, Sussex. 

164. L. PYRIVORELLA, Bankes. 

165. L. ULICICOLELLA, Sta. (1854). 


GRACILARIIDES. 
166. ORNIX LOGANELLA, Sta. (1848). Scotland. 


NEPTICULIDES. 


167. NEPTICULA FLETCHERI, Tutt. Confused with NV. anomalella. 
168. N. TORMINALIS, Wood. 


169. N. poTERiI, Sta. (1858). S. of England. 

170. N. HODGKINSONI, Sta. Lancashire. 

171. N. CONFUSELLA, Wlsm. 

172. N. QUINQUELLA, Bedell (1848). 8S. of England. Local. 
173. N. WoOLHOPIELLA, Sta. 

174. N. SUBAPICELLA, Sta. 


N.B.—Mr. Tutt thinks that all the above-named Nepticulides 
will probably be discovered on the Continent. 


ERIOCRANIIDES. 


175. ERIOCRANIA FIMBRIATA, Walsm. A rare species. 
176, E. SALOPIELLA, Stainton. Shrewsbury, S. England. 


GLYPHIPTERYGIDES. 
177. Glyphipteryx thrasonella, var. CLADIELLA, Sta. Deal to the Shet- 
lands. 
YPONOMEUTIDES. 


178. ARGYRESTHIA HRARIELLA, Sta. Perhaps a form of A. conjugella. 
179. A, SEMIFUSCA, Haworth (1829). N. and W. of England. 


In the last edition (1892), there were 89 species and 
varieties of British Lepidoptera recorded as probably or 
possibly endemic. About thirty of these are now omitted, 
either from having been found on the continent or from 
their presenting too slight differences from continental 
forms. Yet the list is now increased to about double 
its former numbers, showing a great amount of activity in 
our collectors, but more especially due to the intelligent 
interest now taken in varieties as indications of the process 
of evolution of new species. As we can hardly suppose con- 


CHAP. XVI THE BRITISH ISLES 349 


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 endemic. 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 will remain permanently as peculiar British species. 

Mr. Tutt is of opinion that most of the species and 
varieties recorded from Britain generally will be found on 
some part of the continent, but that most of our Hebridean, 
Shetland, Irish, Scotch, Cumbrian, and Welsh races are 
peculiarly our own, being in fact incipient species in 
process of adaptation to the very pronounced insular 
climate of those regions. 


Coleoptera. 


We will now pass on to the Coleoptera, cr beetles, an 
order which has been of late years energetically collected 
and carefully studied by British entomologists. 


List of the Species and Varieties of Beetles which, so far as at presenti known, 
are confined to the British Islands. Those added since the first edition 
are marked with an asterisk. 


CARABIDA. 


. “Bembidium saxatile, var. vECTENSIS (Fowler). Isle of Wight. 
DRoMIUS VECTENSIS (Rye). Common in the Isle of Wight, also in 

Kent, and at Weymouth and Seaton. Closely allied to D. sigma. 
Harpalus latus, var. METALLESCENS (Rye). Unique, but very 
marked! South coast. ‘‘ Perhaps a sport or a hybrid” (Fowler). 
. ACUPALPUS DERELICTUS (Dawson). Unique! North Kent. Canon 
Fowler thinks it may be a variety of 4. dorsalis. 


EF wo Ne 


DYTICID. 
5. *Acilius sulcatus, var. scoTicus (Curtis). Scotland. A melanic 
variety. | 
HELOPHORIDS, 
6. OCHTHEBIUS POWERI (Rye). Very marked. S. coast. A few speci- 


‘mens only. 
7. *O. ZNEUS (Steph. ). 


Bok 


350 


ISLAND LIFE PART II 


39. 


BRACHYELYTRA. 


. OCYUSA HIBERNICA (Rye). Ireland, mountain tops, and at Braemar. 
. *OXYPODA TARDA (Sharp). 


53 PECTITA (Sharp). Scotland. 


= VERECUNDA (Sharp). Scotland, also London districts, 
. HOMALOTA DIVERSA (Sharp). 
re OBLONGIUSCULA (Sharp). Scotland, also England and 
Ireland 


is PRINCEPS (Sharp). A coast insect. 
a CURTIPENNIS (Sharp). Scotland and near Birmingham, 


. H, levana, var. SETIGERA (Sharp). 
. STENUS OSCILLATOR (Rye). Unique! South Coast. May be a 


hybrid. 


. TROGOPHLAUS SPINICOLLIS (Rye). Mersey estuary, unique! Most 


distinguishable, nothing likeit in Europe. Perhaps imported from 
another continent. 


. TROGOPHLZUS ANGLICANUS (Sharp) Plymouth, Many examples. 


Allied to the preceding, and perhaps also a chance introduction. 


. EUDECTUS WHITEI (Sharp). Scotch hills. A variety of £. Giraudi 


of Germany (the only European species) fide Kraatz (Sharp). 


. HoMALIUM RUGULIPENNE (Rye). lExceedingly marked form, 


Northern and western coasts ; rare. 


. *MYCETOPORUS MONTICOLA (Fowler). Cheviots and Inverness-shire, 


SCYDMANIDA. 
. *ScyDMNUS POWERI (Fowler). 8S. England. A recent discovery. 
. *$. PLANIFRONS (Blatch). 5% Ss 


PSELAPHIDA. 


. Bryaxis cotus (De Saulcy). Scotland. 
_ BYTHINUS GLABRATUS (Rye). Sussex coast; also Isle of Wight; a 


few specimens ; ; very distinguishable ; myrmecophilous (lives in 
ants’ nests). 


TRICHOPTERYGIDA. 
. PTINELLA MARIA (Matthews) Derbyshire, 
. TRICHOPTERYX SARE (4 Pie ) Notts. 
F POWERI 1S ag ee) one 
je EDITHIA ho te ) Kent. 
a *ANGUSTA ( a ) Leicestershire. 
5 KIRBII Lc hee ) Norfolk. 
- FRATERCULA ( 5 ) Leicestershire. 
a WATERHOUSII ( ‘ ) 
“ CHAMPIONIS (_,, ) Wicken Fen. 
- JANSONI ( ) Leicestershire. 
SUFFOCATA (Haliday). Ireland, Co. Cork. 


CARBONARIA (Matthews). Notts. 
PrrniuM HALIDAYI (Matthews). Sherwood Forest. 
a CALEDONICUM (Sharp). Scotland ; very marked form, 
»,  INSIGNE (Matthews). London district. 


a 


42. 
43. 


44, 


45. 
46. 


47. 


48. 


49, 


51. 


59. 


CHAP. XVI THE BRITISH ISLES 351 


*ORTHOPERUS MUNDUS (Matthews). Oxfordshire. 
*Q. PUNCTULATUS (Matthews). Lincolnshire. 
ANISOTOMID. 


AGATHIDIUM RHINOCEROS (Sharp). Old fir-woods in Perthshire ; 
local, many specimens ; a very marked species. 
ANISOTOMA SIMILATA (Rye). South of England. Two specimens. 
a LUNICOLLIS (Rye). North-east and South of England, a 
very marked form ; several specimens. 


PHALACRIDA. 


PHALAOCRUS BRISOUTI (Rye). South of England. Rare. ‘‘ Perhaps 
a small form of P. coruscus” (Fowler). 


RHIZOPHAGIDZ. 


RHIZOPHAGUS OBLONGICOLLIS (Blatch and Horner). Staffordshire. 
‘Closely allied to R. nitidulus, but apparently distinct” (Fowler). 


CRYPTOPHAGIDE. 
ATOMARIA DIVISA (Rye). Unique! South of England. 


LATHRIDIIDA. 


. Melanophthalma transversalis, var. WOLLASTONI (Waterhouse). South 


coast, and Lincolnshire. 


BYRRHIDA. 


SYNCALYPTA HIRSUTA (Sharp). South of England, local. ‘Closely 
allied to S. setigera”’ (Fowler). 


HETEROCERIDA. 


. HETEROCERUS BRITANNICUS (Kuwert). Dumfries. ‘‘ Apparently quite 


distinct ” (Fowler). 
MoRDELLID&. 


. ANASPIS SEPTENTRIONALIS. Scotland (1891). (Champion). 


a GARNEYSI (Fowler). London District. (1890). 


TELEPHORIDA. 


. TELEPHORUS DARWINIANUS (Sharp). Scotland, sea-coast. A stunted 


form of abnormal habits. Perhaps a variety of 7. litura’us. 
Bs figuratus, var. CRUACHANUS (Chitty). Ben Cruachan, 
Loch Awe. A melanic variety. 


CYPHONIDA. 


. CYPHON PUNCTIPENNIS (Sharp). Scotland. 


ANTHICIDA. 


. ANTHICUS SALINUS (Crotch). South coast. 


3 scoricus (Rye). Loch Leven ; very distinct ; many speci. 
mens. 


352 ISLAND LIFE PART II 


CIOIDA. 


60. *CIS BILAMELLATUS (Wood). West Wickham, Kent. ‘‘ Perhaps im- | 
ported. Has the appearance of an exotic Cis” (Fowler). 


TOMICIDA. 
61. *Pityophthorus lichtensteinii, var. scoricus (Blandford). Scotland. 


CURCULIONIDA. 


62. Ceuthorhynchus contractus, var. PALLIPES (Crotch). Lundy Island ; 
seyeral specimens. A curious variety only known from this island. 

63. LIOSOMUS TROGLODYTES (Rye). A very queer form. Two or three 
specimens. South of England. 

64. *Orchestes ilicis, var. NIGRIPES (Fowler). London District. -(1890.) 

65. Smicronyx Reichel, var. CHAMPIONIS (Fowler). Folkestone. 

66. APION RYEI (Blackburn). Shetland Islands. Several specimens. 
Perhaps a var. of A. fag?. 


CHRYSOMELIDZ. 
67. Chrysomela staphylea, var. sHARPI (Fowler). Solway district. 


HALTICID. 
68. LONGITARSUS AGILIS (Rye). South of England ; many specimens. 
69. ‘3 DISTINGUENDA (Rye). South of England ; many speci- 
mens. 


70. PSYLLIODES LURIDIPENNIS (Kutschera). Lundy Island. <A very 
curious form, not uncommon in this small island, to which it 
appears to be confined. ‘‘An extreme and local variety of 
P. chrysocephala” (Fowler). 


| CoccINELLID&. 
71. ScyMNUs LIviDUs (Bold). Northumberland. A doubtful species. 


Of the seventy-one species and varieties of beetles in the 
preceding list,aconsiderable number no doubtowe their pre- 
sence there to the fact that they have not yet been discovered 
or recognised onthe continent. This is almost certainly.the 
case with many of those which have been separated from 
other species by very minute and obscure characters, and 
especially with the excessively minute Trichopterygide 
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- 


CHAP. XVI THE BRITISH ISLES 353 


ditions there prevailing, which have Jed in some cases toa 
change of habits, so that a species of weevil (Otiorhynchus 
maurus) always found on mountain sides in Scotland here 
occurs on the 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 
the coast of Scotland and Ireland, with the Isle of Man and 
the Scilly Islands, none of which have been yet thoroughly 
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. 


Trichoptera. 
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 habits of the larve of these insects, 
some living in ponds or rivers, others in lakes, and others 
again only in clear 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. 


Trichoptera peculiar to the British Isles. 


1. PHILOPOTAMUS INSULARIS. (? 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 


354 ISLAND LIFE PART II 


with P. montanus, a species found both in Britain and on the continent, 
but it differs in its strikingly yellow colour, and less pronounced markings. 
All the specimens from Guernsey are alike, and resident entomologists 
assured Mr. McLachlan that no other kind is known. Strange to say, 
some examples from Jersey differ considerably, and have been named 
P. castaneus, McL. Even should this peculiar variety be at some future 
time found on the continent it would still be a remarkable fact that 
the form of insect inhabiting two small islands only twenty miles apart 
should constantly differ ; but as Jersey is between Guernsey and the coast, 
it seems just possible that the more insular conditions, and perhaps some 
peculiarity of the soil and water in the former island, have really led to 
the 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—Setodes argentipunctella and Rhyacophila munda, but both 
have now been taken on the continent. 

2. MESOPHYLAX IMPUNCTATUS, var. ZETLANDICUS.—A variety of a 
South and Central European species, one specimen of which has been 
found in Dumfriesshire. The variety is distinguished by its small size and 
dark colour. 


Land and Freshwater Mollusca, 


My friend Mr. T. D. A. Cockerell who furnished the list 
of peculiar British species for the last edition of this work, 
being now resident in the United States, I applied to Mr. 
John W. Taylor, F.L.S., author of the admirable Mono- 
graph of the Land and Freshwater Mollusca of the British 
Isles, who not only drew up a new and complete list of 
the peculiar British species and varieties, but has appended 
thereto some valuable and suggestive introductory remarks. 
I therefore print his contribution entire. It will be seen 
that the three peculiar species are now increased to seven, 
while the eighty peculiar varieties, although for various 
causes thirteen have been omitted, have, by the addition 
of fifty-eight new ones, reached the large number of one 
hundred and twenty-four. This, however, 1s what might 
be expected, since in islands generally this group of animals 
presents more peculiar forms than any other. 


The Endemic Land and Freshwater Mollusca of the British 
Isles. By John W. Taylor, F.LS. 


In the first edition of the present work, four species 
only were noted as being, so far as was then known, 
exclusively British. Two of these, Limnea involuta and 
Assiminea grayana, are still peculiar to the British Isles, 
and unknown in other parts of the world. 


CHAP. XVI THE BRITISH ISLES 855 


The acknowledged increasing abundance specifically and 
individually of the more primitive species of our land and 
freshwater shells, as we proceed westward and northward 
in the British Isles, points to the gradually lessening com- 
petition to which they are subjected by the stronger and 
more highly organised forms, more especially characteristic 
of Eastern England. 

These more dominant species are gradually dispossess- 
ing the weaker races of districts in which they formerly 
existed, leading to their more decided restriction to 
western areas, and to-a more marked discontinuity of the 
localities some of them still inhabit in Eastern England. 

The affinity shown by the flora of South-west Ireland 
to that of South-western Europe, is likewise to a certain 
extent shared by the Mollusca: the fact is of great interest, 
and displays the last footholds of these waning species in 
Western Europe. 

The North American species or varieties of land and 
freshwater shells discovered in the West of England and 
chiefly in the Lancashire district, where so many able and 
enthusiastic conchologists are congregated, may probably 
be artificial through unintentional introductions due to the 
importation of cotton and other products from the United 
States, more especially during the progress of the American 
Civil War; but it must not be overlooked that the geo- 
graphical position occupied by these forms is in broad 
harmony with the western habitat in our islands of those 
American species of plants and other organisms which still 
linger in this country, and leads us to speculate upon the 
possibility of these species being also relics of a former 
greater abundance and wider distribution in this country 
of these and probably other forms, which are now restricted 
to the American continent or other remote regions. 

The appended list of British species and varieties of 
land and freshwater shells contains no forms recorded for 
continental Europe, yet in all probability this apparent 
difference is really due in many cases merely to the 
particular forms not having been, as yet, separated or 
distinguished, or because they are differentiated under 
other names, and thus to some extent secured from easy 


356 ISLAND LIFE PART II 


recognition and correlation. It is therefore only by an 
actual and careful comparison of authentic specimens that 
a perfectly reliable list could be drawn up, which would 
fairly represent the knowledge of the present day. 

It is, however, highly probable that our insular and 
peculiar conditions do tend to evolve variations in harmony 
with the local environment, and thus conduce to stamp 
upon many of our species a recognisably different general 
facies to that of continental individuals of the same 
species. The peculiar species are now six in number and 
embrace— 


Limnea involuta, Thompson.—A pond snail with a small, polished, 
amber-coloured shell, found only in a small alpine lake and its inflowing 
stream on Cromaglaun Mountain, near the Lakes of Killarney. It was 
discovered in 1838, and has frequently been obtained since in the same 
locality. It is more properly classed as an aberrant variety of Limnea 
peregra, rather than as a distinct species. . 

Azeca elongata, Taylor.—A large species of this very limited genus, 
distinguished by its elongate form and comparatively simple oral armature. 
It has hitherto only been met with in North Wales and in the Yorkshire 
Highlands. 

Clausilia cravenensis, Taylor.—A fine species of this group, hitherto 
confounded with Clausilia dubia, and confined to the uplands of the North 
of England. 

Paludestrina jenkinsi, Smith.—A small ovoviviparous species, inhabit- 
ing many localities in England and Ireland, both inland and estuarine. It 
was discovered some years ago, and first described in 1889. 

Paludestrina taylori, Smith.—A minute species, discovered in the 
Lancashire canals in 1900. It is very distinct from any known British 
species, and shouid be grouped apart from P. jenkinst. P. taylori is an 
oviparous species, and, judging from its peculiar and characteristic egg 
capsules, would be more properly associated with the American group, 
Amnicola. 

Pisidium hibernicum, Westerlund.—An Irish species of this perplexing 
genus, which has been discriminated by Dr. Westerlund. 


In addition, however, to the six distinct species, 
enumerated above as not known to occur elsewhere, there 
are a considerable number of more or less well-marked 
varieties, which seem to be also peculiar to our islands, 
and are probably in a great measure a reflex of the 
characteristic insular environment to which they are 
subjected. 

The following list of such forms is therefore given, in 
the hope that it may be useful in calling attention to 
those varieties which are not yet positively known to occur 


———— .- o™ 


CHAP. XVI THE BRITISH ISLES 357 


elsewhere than in our islands, and thus tend to lead to a 
more accurate knowledge of the geographical limitations 
of the variations of our native species. 


LIST OF THE SPECIES AND  vatanre oF LAND AND FRESHWATER 
SHELLS, WHICH, SO FAR AS AT PRESENT KNOWN, ARE BELIEVED 
TO BE PECULIAR TO THE BRITISH ISLES, OR NOT FOUND ON THE 
CONTINENT. 
Testacellide. 


1. Testacella maugei, v. nigra, Collinge. Tenby. 


Limacide. 
2. Amalia gagates, v. rava, Williams. West England and Ireland. 
3 Z aM v. babori, Collinge. 
4, 5,  sowerbyi, v. bicolor, Cockerell. Ealing. 
5. ¢ ” v. nigrescens, Roebuck. Wales and South and 
South-west England. 
6 2s ee v. fusco-carinata, Cockerell. South of England. 
‘s fie i, v. nigro-carinata, Collinge. South-west of England. 
8. Limax maximus, ¥. lilacina, Roebuck. 
ee a v. pallido-dorsalis, Hudson. N. England. 
m. =, FP v. hedleyi, Collinge. Ireland. 
li. ,, flavus, v. suffusa, Roebuck. England. Melanic form. 
ae 5,  v. grisea, Roebuck. England. Melanic form. 
Bey, ,,  ¥. lineolata, Collinge. Yorkshire. 
14. ,, marginatus, v. maculata, Roebuck. Ireland and Western 
Britain. 
15. v. decipiens, Cockere‘l.. Ireland and England. 
16. Agriolimax levis, v. pallida, Roebuck. 
cs. me », v maculata, Cockerell. 
Arionide. 


18. Arion ater, v. albo-lateralis, Roebuck. North Wales and I. of Man 
and Shetlands. Very distinct. 

19. ,,  ,, v. cinerea, Roebuck. England. 

20. ,, 4, ¥. reticulata, Roebuck. Ireland. 

21. ,, hortensis, v. cerulea, Collinge. England and Ireland. 

ie re v. fallax, Cockerell. England. Common at Boxhill. 

23. 5,  circumscriptus, v. flavescens, Collinge. Scotland. 

24. Geomalacus maculosus, v. fasciata, Cockerell. Ireland. 


Helicide. 
25. Hyalinia helvetica, v. bicolor, Cockerell. Kent. 
26. iy se v. viridans, Cockerell. 
27. ‘i nitidula, v. lucens, Pulteney. Tenby. 
28. " erystallina, Vv. complanata, Jeffr. Near Bristol. 


29. ae fulva, v. viridula, Taylor. Yorkshire. 
30. Helix nemoralis, v. hibernica, Westl. Ireland. 


358 


31 


32. 
33. 
34. 
35. 
36. 
87. 
38. 
39. 
40. 
41, 
42. 
43. 


44, 
45. 
46. 
47. 
48. 
49. 
50. 
51. 


52. 
53. 
54. 
55. 
56. 
57. 
58. 
59. 
60. 
61. 
62. 


63. 
64. 
65. 
66. 


67. 
68. 
69. 
70. 


(fs 
72. 


ISLAND LIFE PART IL 


. Helix hortensis, v. lilacina, Taylor. 


99 


39 
99 


99 


93 


99 


9 


ve v. Olivacea, Taylor. 
oe v. luteo-labiata, Adams. 
cantiana, v. albo-cincta, Cockerell. 
+ v. sinistrorsa, Taylor. 
rufescens, v. manchesterensis, Locard. Lancashire. 
hispida, v. depilata, Alder. England. 
»  v. subglobosa, Jeffr. England. 
3... albo-cincta, Taylor, 
granulata, v. cornea, Jeffr. Dorset. 
3 v albida, Tye. 
pisana, v. tenuis, Taylor. Tenby. 
caperata, v. major, Jeffr. England, Wales, and Scotland. 


Distinct. 
v. nana, Cockerell. England. 
Ds v. subscalaris, Jeffr. Wales, Ireland. 


i v. alternata, Cockerell, Kent. 
virgata, v. subaperta, Jeffr. Bath. 
»  ¥v. carinata, Jeffr. Wareham, Dorset. 
> -% miner, VTaytor,. 1. ef Wight. 
»,  % coalita, Taylor. Tenby. 
acuta, v. nigrescens, Taylor. I. of Man. 


Pupidee. 


Pupa secale, v. edentula, Taylor. Yorkshire. 
anglica, v. pallida, Jeffr. Not rare. 
Vertigo moulinsiana, v. bidentata, Jeffr. Connaught. 


pygmea, v. albina, Chaster. Nottingham. 
substriata, v. albina, Standen. Cumberland and Ireland. 


Clausilia biplicata, v. nelsoni, Taylor. Surrey. 


rolphi, v. nitida, Cockerell. S. England. 
5 v. curta, Jenner. Sussex. 
bidentata, v. parvula, Turton. Ireland. 
» . v. suttoni, Westl. N. England. 
cravenensis, Taylor. N. England. 


Stenogyride. 


Zua lubrica, v. hyalina, Jeffr. Wales, Scotland, &c. 


v. morseana, Doherty. Also N. American. 


Azeca elongata, Taylor. Wales and N. England. 
Cecilioides acicula, v. anglica, Bourget. England. 


Suceinetdce. 


Succinea elegans, v. minor, Jeffr. England. 


. v. rufescens, Cockerell. England, Ireland. 
putris, v. aurea, Cockerell. Ireland. 
oblonga, v. sinistrorsa, Taylor. Scotland. 


Limneide. 


Limnea involuta, Thompson. Ireland. 


peregra, v. burnetti, Alder. Scotland. Very distinct. 


CHAP, XVI THE BRITISH ISLES 359 
73. Limnea peregra, v. maritima, Jeffr. Gt. Britain. 
74. . ¥ v. lineata, Bean. England. 
oe ys »,  ¥ stagnaliformis, Taylor. England, 
76, »,  auricularia, v. reflexa, Nelson. Yorkshire. 
i. a Ms v. gibbosa, Taylor. Yorkshire. 
78. », palustris, v. conica, Jeffr. England, Ireland. 
79. te a v. tincta, Jeffr. England, Wales. 
80. iy - v. albida, Nelson. England. 
81. a as v. obesa, Taylor. Kent. 
82. os v. fasciata, Nelson. England. 
83. oF truncatula, v. elegans, Jeffr. England, Ireland. — Distinct. 
84. v. fusca, Cockerell. Wales. 


85. Amphipeplea ‘elutinosa, v. mucronata, Jeffr. 

86. Physa heterostropha, Say. W. and Mid-W. England ; also N. 
America, 

87. Aplecta hypnorum, v. cuprella, Rowe. 

88. Planorbis fontanus, v. albida, Nelson. 


89. ¥9" v”. minor, Melvill. 

90. ‘ dilat tatus, Gould. Lancashire ; ; also N. America. 

v1. 3 parvus, v. compressa, Lloyd. Also a N. American species. 
92. a spirorbis, v. prisca, Taylor. England. 

93. - carinatus, v. alba, Hudson. , England. 

94. marginatus, v. sinistrorsa, Taylor. England. 

95. me albus, v. sulcata, Taylor. 

96. si contortus, v. excavata, Cockerell. Iveland. 

97. v. minor, Taylor. Yorkshire. 


98. Velletia lacustris, v. compressa, Jeffr. England. 


Cyclostomide. 
99, Cyclostoma elegans, v. marmorea, Brown. England and Scotland. 


Paludestrinide. 
100. Paludestrma taylori, Smith. Lancashire. 
101. s jenkinsi, Smith. England and Ireland. 
102. ‘5 ra v. carinata, Marshall. 
108. ea 5 v. tumida, Jenkins. 
104, a ventrosa, v. minor, Jeffr. Wales. 
105. =" a v. decollata, Jeffr. Wales and Guernsey. 
106. “ ie v. ovata, Jeffr. Wales. 
107. = < v. elongata, Jeffr. Guernsey. 
108. e. an v. pellucida, Jeffr. Pembroke and Yorkshire. 
Unionide. 


109. Unio tumidus, v. richensis, Harting. Regent’s Park. Peculiar form. 
110. ,, pictorum, v. latior, Jeffr. Oxford. 

lll. ,, margaritiferus, v. olivacea, Brown. Westmoreland. 

112. Anodonta cygnea, v. incrassata, Shepp. England. 

113. ? oe v. pallida, Jeffr. England and Wales. 


Corbiculide. 


114. Spherium corneum, v. compressa, Gray. 
115. re wd v, Minor, Gray. 


360 ISLAND LIFE PART II 


116. Spherium corneum, v. stagnicola, Jenyns. 
LTT: a lacustre, v. rotunda, Jeffr. Wales. 
118. Pisidium pusillum, v. grandis, Adams. Lancashire. 


119. “< in v. circulare, Cockerell. 
120. + nitidum, v. globosa, Melvill. Lancashire. 
121. oe hibernicum, West]. Ireland. 


ESTUARINE OR MARINE PULMONOBRANCH. 
122. Assiminea grayana, Leach. Thames Estuary. 


Peculiarities of the British Flora.—Thinking it probable 
that there must also be some peculiar British plants, but 
not finding any enumeration of such in the British Floras 
of Babington, Hooker, or Bentham, I applied to the 
greatest living authority on the distribution of British 
plants—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 Rubi 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 Student's Flora, where-the brambles are described 
by Baker, a botanist well acquained 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 with continental 
specimens, while in many cases the permanence of the 


CHAP. XVI THE BRITISH ISLES 361 


characters distinguishing them have been tested by culti- 
vation under new conditions, and I am now enabled to 
give a much more extensive list of the species or forms 
which at present seem to be peculiar. For the following 
list I was primarily indebted to Mr. Arthur Bennett of 
Croydon, and for the present edition I have obtained the 
assistance of Mr. W. H. Beeby and Messrs. H. & J. Groves, 
and the present list is the result of a final revision by 
the latter gentlemen. All these are well known for their 
devotion to the critical study of British plants. 


LisT OF SPECIES, SUB-SPECIES, AND VARIETIES OF FLOWERING PLANTS 
FOUND IN GREAT BRITAIN OR IRELAND, BUT NOT AT PRESENT 
KNOWN IN CONTINENTAL EuRopPE. SiR JOSEPH HOOKER’S NOTES 
IN THE FORMER EDITION ARE ALSO GIVEN. 


Ranunculus aquatilis, var. cambricus (Ar. Benn.). Anglesey. Perhaps 

an extreme form of R. fluitans (Lam. ). 

. R. scoticus (Marshall). Scottish Highlands and Ireland. ‘‘ Perhaps 
a sub-species of R. Flammula.” (Groves.) 

. Caltha radicans (Forst.). ‘‘A much disputed species, or form of C. 
palustris. It isa relatively rare plant:” (J. D.H.) ‘‘ Certainly 
distinct from the Scandinavian form.” (Ar. Bennett. ) 

4. Arabis ciliata (R. Br.) In Nyman’s Conspectus Flore Europew. this 
species is given as found in England and Ireland only. 

‘** A very much disputed form of a plant of very wide distribution 
in Europe and North America.” (J. D. H.) 

5. Brassica monensis (Huds, ), ‘‘This and the continental B. Chetranthus 
(also found in Cornwail) are barely distinguishable from one 
another.” (J. D. H.) 

6. Cochlearia micacea (Marshall). Perth, Argyll. ‘‘ Closely related to 
C. alpina.” (Groves.) 

7. Lepidium Smithii (Hook.), var. alatostyla (Towns.). Hampshire. 

8. *Helianthemum guttatum (Mill), var. Breweri (Planch). Anglesey. 
‘Very doubtful local plant. H. guttatum (true) has lately been 
found in the same locality.” (J. D. H.) 

9. *Polygala vulgaris (L.), var. grandiflora (Bab.). Sligo, Ireland. ‘‘A 
very distinct variety.” (J. D. H.) 

10. Sagina Boydii (F. B. White). Braemar. ‘‘ Apparently a distinct 
species.” (Groves. ) 

11. *Geranium sanguineum (L.), var. lancastriense (With. ). Lancashire. 
Mr. Bennett writes: ‘‘I have grown G. sangwinewm and its pros- 
trate variety in sand, and neither became lancastriense.”’ 

12. Genista tinctoria (L.), var. humifusa (Dickson). Cornwall. ‘‘A 
decumbent hairy form confined to the Lizard.” (J. D. H.) 

13. *Trifolium repens (L.), var. Townsendii (Bab.). Scilly Isles. ‘A 
well- marked form by its rose-purple flowers. Confined to the Scilly 
Isles.” (J. D. H.) 

14. Rosa tomentosa, var. Woodsiana (Groves). 

15. Rosa hibernica, var. Grovesii (Baker). ‘‘R. hibernica is now considered 

a hybrid.” (Groves. ) 


er 


CoO 6b 


362 ISLAND LIFE PART II 


16to34. The following are the endemic Rubi given in the Rev. W. M. Rogers’s 
‘* Handbook of the British Rubi”: R. Rogersii (Linton), R. latifolius 
(Bab.), R. durescens (W. R. Linton), R. mercicus (Bagnall), R. 
ramosus (Briggs), R. lentiginosus (Lees), R. Colemanni (Bloxam), 
R. iricus (Rogers), R. criniger (Linton), R. cinerosus (Rogers), R. 
regillus (Ley), R. Griffithianus (Rogers), R. melanodermis (Focke), 
R. thyrsiger (Bab.), R. Lintoni (Focke), R. longithyrsiger (Bab. ), 
R. Marshalli (Focke and Rogers), R. Durotrigum (R. P. Murray), 
R. ochrodermis (Ley). 

35. Pyrus aria (Sm.), var. rupicola (Syme). ‘‘ A very local form, confined 
to Gt. Britain.” (Baker.) 

36. Callitriche obtusangula (Le Gall), var. Lachii (Warren). Cheshire. 
to = intermediate between two sub-species of C. verna.” 
(J; D.. H, 

37. *C&nanthe fluviatilis (Coleman). South of England. ‘‘The fluitant 
form of @. Phellandrium.” (J. D. H.) 

38. Centaurea scabiosa (L.), vas. succiszefolia (Marshall). Sutherland. 

39. Anthemis arvensis (L.), var. anglica (Spreng). N. Coast of England. 
‘*A maritime form with more fleshy leaves formerly found near 
Durham. It has other very trifling characters.” (J. D. H.) 

40. Arctium pubens (Bab. ). 

41. Hieracium holosericeum (Backh.). Scotch Alps. 


42. H. gracilentum (Backh. ). me 

43. H. lingulatum (Backh.). = A var. of this in 
Scandinavia. 

44, H. senescens (Backh.). Bs 

45. H. chrysanthum (Backh. ). 

46. H. zetlandicum (Beeby). Shetland Is. 

47. H. iricum (Fr.). Teesdale, Scotland and Ireland. 

48. H. Gibsoni (Backh.). Yorkshire and Westmoreland. 

49. H. nitidum (Backh.). Lower glens of the Scotch Alps. 

50. H. langwellense (Hanb.). Caithness. 

51. H. pollinarium (Hanb.). Sutherland 

52. H. scoticum (Hanb.). Sutherland and Caithness. 

53. H. Backhousei (Hanb.). Perth, Aberdeen, Banff, Inverness. 

54. H. caledonicum (Hanb.). Caithness and Sutherland. 

55. H. farrense (Hanb.). Sutherland and Shetland Is. 

56. H. proximum (Hanb.), Caithness. Mr. Beeby remarks on these 


supposed peculiar species: ‘‘ We know that the great bulk of our 
named Hieracia are not merely states due to situation ; their 
characters have been proved to be permanent by cultivation under 
varied conditions. Their kind of variation is therefore specific in 
its nature.” 

57. *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.) 

58. Erythrea capitata (Willd.), var. spherocephala (Towns.). Isle of 
Wight. ‘A form of Z. centawriwm utterly anomalous in its genus 
in the insertion of the stamens. A monster rather than a species.” 
(J. D. H.) 

59. *Erythrea latifolia (Sm.). On the sandy dunes near Liverpool. ‘A 
local form.” (J. D. H.) 

60. Myosotis collina (Hoffm.), var, Mittenii (Baker). Sussex. 


CHAP, XVI THE BRITISH ISLES 363 


61. Veronica officinalis (L.), var. hirsuta (Hopk.). Ayr, Scotland. 

62. Veronica arvensis (li.), var. eximia (Towns.). Hampshire. 

63. Euphrasia scotica (Wettstein). N. of Scotland. ‘‘ Very closely related 
to EL. minima.” 

64. Mentha alopecuroides (Hull). Nearest to IZ. dulctssima (Dum. ). 

65. Mentha pratensis (Sole). Only once found. 

66. *Spiranthes Romanzoviana (Cham.). Ireland. (N. America.) 

67. *Sisyrinchium angustifolium (Mill.), Ireland. (Arctic and Temp. N. 
America. ) 

68. *Sisyrinchium californicum (Ait.). Ireland. (N. America.) 

69. Allium Babingtonii (Borrer). West England. West Ireland. ‘‘A 
form of A. ampeloprasum, itself a naturalised species.” (J. D. H.) 

70. Potamogeton Griffithii(Ar. Bennett), Carnarvon. ‘‘ Nearest to thisisa 
probable hybrid from N. America, but not identical.” (Ar. Bennett. ) 

71. Potamogeton pusillus (L.), swb-sp. Sturrockii (Ar. Benn.). Perth. 

72. Potamogeton pusillus (L.), var. rigidus (Ar. Benn.). Orkneys, 
Shetlands. 

73. *Eriocaulon septangulare (With.). Hebrides, Ireland, N. America. 

74. Scirpus uniglumis (Link), var. Watsoni (Bab.). Scotland, England. 
‘‘This is a variety of a sub-species of the common 8S. palustris.” 
(J. D. H.) | 

75. Luzula pilosa (Willd.), var. Borreri (Bromf,). ‘‘ Perhaps a hybrid.” 
(Groves. ) 

76. *Carex involuta (Bab.). Cheshire. ‘‘A distinct enough plant, but 
probably a hybrid between C. vesicaria and C. ampullacea, found 
in one place only.”’ (J. D. H.) 

77. Carex glauca (Murr.), var, stictocarpa (Sm.). Scotland. 

78. Carex preecox (Jacq. ), var. capitata (Ar. Benn.). Ireland, ‘‘ A remark- 
able plant (monstrosity ?) simulating C.capitata (L.).” (Ar. Bennett). 

79. *Carex Grahami (Boott). ‘‘A mountain form of C. vesicaria.” (J. 
Dp. A. 

80. *Spartina Townsendi (Groves). Hampshire. ‘‘ Perhaps a hybrid.” 
(Groves. ) 

81. Agrostis nigra (With.). ‘‘ Apparently a var. of A. vulgaris.” 

82. Deschampsia flexuosa (Trin.), var. Voirlichensis (J. C. Melvill). Perth. 

83. *Deyeuxia neglecta (Kunth), var. Hookeri (Syme). Ireland. ‘*A 
distinct variety confined to Lough Neagh.” (J. D. H.) 

84. Glyceria maritima (Willd.), va7. riparia (Towns.). Hampshire. 

85. Poa Balfouri (Bab.). Scotland. ‘‘ An alpine sub-variety of a variety 
of the protean P. nemoralis.” (J. D. H.) 

86. Bromus mollis (L.), var. interruptus (Hackel). ‘£‘ Possibly a colonist 
of unknown origin, Perhaps a monstrosity.” (Groves.) : 


Even should it ultimately prove that none of the 
more or less doubtful forms are found to be peculiar 
British varieties, yet the number admitted after so rigor- 
ous an examination is about what we should expect in 
comparison with the limited amount of speciality we have 
seen to exist in other groups. The three or four Ameri- 
can species which inhabit the extreme west and north- 
west of the British Isles, but are not found on the con- 

B B 


364 ISLAND LIFE PART II 


tinent 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 temperate zone, we can only 
explain their presence with us and not further east b 
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 European plants which 
occur in the same districts. 

We may here notice the interesting fact that [Ireland 
possesses no less than twenty species or sub-species of 
flowering plants not found in Britain, and some of these 
may be altogether peculiar. As a whole they show the 
effect of the pre-eminently mild and insular climate of 
Ireland in extending the range of some South European 
species. The following list of these plants, for which Lam 
indebted to Mr. A. G. More, with a few remarks on their 
distribution, will be found interesting :— 


List oF IRISH FLOWERING PLANTS WHICH ARE NOT FOUND IN BRITAIN. 


. Polygala vulgaris (var. grandiflora). Sligo. 

. Campanula rotundifolia (var. speciosa). W. Ireland. 

. Arenaria ciliata. W. Ireland (also Auvergne, Pyrenees, Crete). 

. Saxifraga umbrosa. W. Ireland (also Pyrenees, N. Spain, Portugal). 
- geum. S§. W. Ireland (also Pyrenees). 
5 hirsuta. 8S. W. Ireland (also Pyrenees). 

Inula salicina. W. Ireland (Scandinavia, Middle and South Europe). 

Erica mediterranea. W. Ireland (W. France, Spain, Portugal). 

» mackaiana (tetralix sub.-sp.). W. Ireland (Spain). 

. Arbutus unedo. 8S. W. Ireland (W. of France, Spain, Portugal, and 
shores.of Mediterranean). 

. Dabeocia polifolia. W. Ireland (W. of France, Spain, and Portugal). 

. Pinguicula grandiflora. 8S. W. Ireland (Spain, Pyrenees, Alps of 
France and Switzerland). 

. Neotinea intacta. W. Ireland (S. France, Portugal, Spain, and - 

shores of Mediterranean). 


SONI D OVP Go PO 


ellen! 
bo He 


—_ 
Oo 


CHAP. XVI THE BRITISH ISLES 365 


ee ee ee 


14. Spiranthes romanzoviana. 8S. W. Ireland (North America). 

15. Sisyrinchiwm angustifolium. W. Ireland (North America, Arctic and 
Temp. ). 

16. Potamogeton lonchites. Ireland. Mr. Arthur Bennett informs me that 
this is certainly not British or European, but may possibly be 
identical with P. fwitans var. Americanus of the U. States. 

17. Potamogeton kirkii (natans sub.-sp.). W. Ireland. (Arctic Europe 2) 

18. Hriocaulon septangulare. W. Ireland, Skye, Hebrides (North 
America). | 

19. Carex buxbaumit. N. E. Ireland, on an island in Lough Neagh (Arctic 
and Alpine Europe, North America). 

20. Deyeuxia neglecta (var. Hookeri). On the shores and islands of Lough 
Neagh. (And in Germany, Arctic Europe, and North America. a 


We find here nine south-west 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. This seems more probable 
than that so many species should have reached Ireland for 
the first time during .the last union with 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 contrasted with 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 Hepatice, some of which present us with phe- 
nomena of distribution of a very remarkable character. 
For the following lists and the information 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 was corrected for 
the last edition by Dr. R. Braithwaite. Several species of 
Hepatice have been added, and the present lists corrected, 
by Mr. Mitten. 


266 


ISLAND LIFE PART II 


LIST OF THE SPECIES OF MossEs AND HEPATICH WHICH ARE PECULIAR TO 


THE BRITISH ISLES (OR NOT FOUND IN EUROPE), 


( Those belonging to non-European genera in italics. ) 


MossEs. 

1. Systegium multicapsulare ...... Sentral and South England. 

2. a2 MELEGODTL ving de aver es South England. 

3. Campylopus Shawii............... North Britain, 

4, re SebfOlIUS: 1.3... 06.6 Treland. 

5. Seligeria calcicola.................. South England. 

GB, Othe WIIGMOlD, 6, « secs ccmcds aves South-west England. 

7. Leptodontium recurvifolium ... Ireland and Scotland. 

8; Tertalg bibernica....cis.ac 2.3.20 Ireland. 

9. Streptopogon gemmascens......... South England. 

10. Grimmia subsqarrosa ............ North Britain. 

1, - SUMP CONE Lh Fae Aroaien woe North Britain. 

12. Glyphomitrium Daviesii......... On Basalt. 

13. Zygodon Nowellii.................. North Britain. 

ta. Bryom Darnesii «2... ex.24.. 42: North England. 

15. Bartramidula Wilsont ......... Ireland and Wales. 

16. Daltonia splachnoides ............ Ireland. 

17. Hookeria loetevirens ............... Ireland and Cornwall. 

eo Ate bg o210C1 M016 200 ae Ireland. 

19. Myurium Hebridarium ......... Hebrides and Atlantic Islands. 

20. Hedwigia ciliata, var. striata... Wales and Scotland. 
HEPATICA. 

1, Gymnomitrium crenulatum ... West England and Ireland. 

2, Prullgnia cermana <...20..5...... Ireland. 

e.. egewia fis yar eo. hss 24058 Ireland, Atlantic Islands, 8. America, 

Africa, &c. 

4, 3 Caly perils eis. Ireland and West of England. 

p, ‘6 microscopica............ Ireland, Madeira. 

6. 3 TAG 5 hk.6 ond: .... Ireland (Killarney). 

ie ‘se diversiloba 5... «x... Ireland (Killarney), Mexico ? 

Bs Vea: CVO yas boigss ware e teas Ireland. 

Buh UN MOM Us oa5. Pnees Reto Ireland, Wales, Cumberland, Mexico? 
10. Mastigophora Woodsii ......... Ireland and West Scotland. 
11. Lepidozia Pearsoni ............... Wales. 

12. a cupressine ............ Ireland. 

13. Bazzania Peargomi ..........5.... Wales. 

14. Hygrobiella myriocarpa ......... Scotland. 

15. Fassombrona Mittenii............ South-west England. 

16. Lophocolia spicata ............... Ireland, Cornwall, Anglesea. 

17, Scapania nimbosa.................: Ireland (Brandon Mountain). 

18. Plagiochila spinulosa ............ Wales, Ireland, and Scotland, Atlan- 
tic Islands. 

19. 3 ambagiosa............ Ireland, India. 

20. 55 punctulata ......... Ireland. 

21. 53 Siableriiie. neces England. 

22, fo CASO LS meetin ee: Ireland. 


= = 


CHAP. XVI THE BRITISH ISLES 367 


23. Jamesoniella Carringtonii ...... Scotland. 

24. Anastrophyllum Doniana ...... Scotland, 

25. Chasmatocolea cuneifolia ...... Ireland. 

26. Acrobolbus Wilsoni............... Ireland, S. America, New Zealand. 
27. Petalophyllum Ralfsii... . ...... Ireland, Cornwall, Devon. 


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 therefore 
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 are a few—aindicated 
by italics—which are in a very different category; for 
they belong to genera which are altogether unknown in 
any other part of Europe, and their nearest allies are to be 
found in the tropics or in the southern hemisphere. The 
four non-European genera of mosses to which we refer 
all have their maximum of development in the Andes, 
while the three non-European Hepatice appear to have 
their maximum in the temperate regions of the southern 
hemisphere. Mr. Mitten has kindly furnished me with 
the following particulars of the distribution of these 
genera :— : 


BARTRAMIDULA. Asia, Africa, S. America, New Zealand, and Aus- 
tralia, but not Europe or N. America. 

STREPTOPOGON is a comparatively small genus, with seven species in the 
Andes, one in the Himalayas, and three in the south temperate zone, 
besides our English species. 

DALTONIA 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. 

HooKERIA (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. 


368 ISLAND LIFE PART II 


The distribution of the non-European genera of 
Hepaticee is as follows :— 


CHASMATOCOLIA. South America and Ireland. 

Acrospo.tsus. A small genus found only in New Zealand and the 
adjacent islands, besides Ireland. 

PETALOPHYLLUM. Asmall genus confined to Australia and New Zealand 
in the southern hemisphere, Algeria, and Ireland in the northern: We 
have also one of the Hepatice—Mastigophora Woodsii—found 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 group of plants as 
to throw any doubt upon their accuracy. The Atlantic 
islands present very similar phenomena in the Rhamphi- 
dium purpuratum, whose nearest allies are in the West 
Indies and South America; and in three species of 
Sciaromium, whose only allies are in New Zealand, 
Tasmania, and the Andes to Patagonia. An analogous 
and equally curious fact is the occurrence in the Drontheim 
mountains in Central Norway, of a little group of four or 
five peculiar species of mosses of the genus Mnium, which 
are found nowhere else; although the genus extends 
over Europe, India, and Japan to the southern hemi- 
sphere.! 

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 
Hepaticee 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 


1 [ am indebted to Mr. Mitten for this curious fact: 


CHAP. XVI THE BRITISH ISLES 369 


a  S 


as ferns or Lycopods; and coupling this antiquity with 
their great 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. 
always such as afford the peculiar conditions: of climate 
and soil best suited to them. The repeated changes of 
temperature and other climatic 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 there is no 


1 The following remarks by the late Dr. Richard Spruce, who made a 
special study of mosses and especially of Hepatice, are of interest. ‘‘ From 
what precedes, I conclude that no existing agency is capable of transport- 
ing the germs of our hepatics of tropical type from the torrid zone to 
Britain, and I venture to suppose that their existence at Killarney dates 
from the remote period when the vegetation of the whole northern hemi- 
sphere partook of a tropical character. If 1 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 pre- 
sent day. The summer sun would 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 have gathered mosses in the Pyrenees 
where the snow had barely left them on August 2nd ; by September 25th 
they were re-covered with snow, and 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, preventing at the same time any formation of ice in the sea 
itself.” This passage is the conclusion of a very interesting discussion on 
the distribution of Hepatice in a paper on ‘‘A New Hepatic from Kil- 
larney,” in the Journal of Botany, vol. 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. 


370 ISLAND LIFE PART II © 


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 
many other: stations which, so far as we can judge, seem 
equally suitable to them. 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 have found in our discussion. 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 we 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 actual existence in such localities 
depends mainly upon vigour of constitution and adapta- 
tion 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 — 
life. 

Concluding Remarks on the Peculiarities of the British 
Fauna and Flora—trThe 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 


1 Mr. W. H. Beeby informs me that in the Shetland Isles, where he has 
collected for five summers, he has found several plants new to the British 
flora, and a few altogether undescribed. Among these latter is the 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. XVI THE BRITISH ISLES aye 


British Isles with the adjacent continent is not altogether 
correct. Among birds we have undoubted peculiarities in 


at least three instances; peculiar fishes are much more 


numerous, and in this case the fact that the Irish species 
are almost all different from the British, and those of the 
Orkneys distinct from those of Scotland, renders it almost 
certain that the great majority of the fourteen peculiar 
British fishes are really peculiar and will never be found 
on the European continent. The mosses and Hepatice 
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, should there not be a proportionate number 
of peculiar British 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 principal island which has been so very thoroughly 
worked. Analogy, therefore, would lead us to conclude 
that many other species or varieties may exist on our 
islands and not on the continent; and when we find that 
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 we cannot say) are 
really endemic British species. 

The general laws of distribution also lead us to expect 
such phenomena. Very rare and very local species are 
such as are becoming extinct , and it 1s among insects, which 
are so excessively varied and abundant, which 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 the best chance of 


“meeting with every degree of rarity down to the point of 


almost complete extinction. But we know that in all 
parts of the world islands are the refuge of species or 


372 ISLAND LIFE PART II 
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 European continent 
should be preserved in some part or other of our islands, 
especially as these present favourable climatic conditions 
such as do not exist on the adjacent continent. 

There is therefore a considerable amount of harmony 
in the various facts adduced in this chapter, as well as 
a complete accordance with 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, JAVA, AND THE PHILIPPINES. 


Position and Physical Features of Borneo—Zoological Features of Borneo : 
Mammalia—Birds—The Affinities of the Bornean Fauna—Java, its 
Position and Physical Features—General Character of the Fauna of Java 
—Differences 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. 


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 east 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 larger part of 
it—from the 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 


i 


ll 


| 


ll 


i 


Walker & Boutall se. 


MAP OF BORNEO AND JAVA, SHOWING THE GREAT SUBMARINE BANK OF SOUTH-EASTERN ASIA. 


The light tint shows a less depth than 100 fathoms. 
The figures show the depth of the sea in fathoms, 


CHAP. XvIT_ BORNEO, JAVA, AND THE PHILIPPINES 375 


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 alluvial deposits in its valleys, indicate great 
changes of level in recent geological times. 

Having thus briefly indicated those physical features of 
Borneo which are necessary for our inquiry, let us turn to 
the organic world. 

Neither as regards this great island nor those which 
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, with the main conclusions to which they 
point ; and then to discuss the mutual relations of some of 


376 7 ISLAND LIFE PART II 
the adjacent islands, and the series of geographical changes 
that seem required to explain them. 


ZOOLOGICAL FEATURES OF BORNEO. 


Mammalia.—The number of species of land-mammalia 
which have now been discovered in Borneo is 175, while 
those which have hitherto not been found elsewhere 
amount to 65, but of these ten are considered to be only 
varieties of species found in other countries. Omitting 
these the peculiar species are exactly one-third of the 
whole, a very large proportion for an island so closely 
surrounded by other lands, and in which so many of the 
large mammals are common to other countries. Such are 
the great ape (Stma satyrus), the Malay bear, the elephant, 
rhinoceros, buffalo and a large deer. But of the peculiar 
species ten are bats, ten are small insectivora, thirteen are 
squirrels, and nine are rats or mice, all groups which are 
likely to be less known in Sumatra and the Malayan and 
Siamese peninsulas, where resident Europeans have been 
less numerous. As there are only about 160 land 
mammals in Europe with its much larger area, greater 
variety of climate and more extensive mountain ranges, the 
fauna of Borneo is seen to be very rich. 

The following list of the peculiar species and varieties 
has been drawn up by Mr. R. Shelford, the curator of the 
Sarawak Museum, to whom I am also indebted for the list 
of the birds peculiar to Borneo at p. 278. 


MAMMALIA PECULIAR TO BORNEO. 


QUADRUMANA (monkeys). 11. Rhinolophus creaghi. 
1. Semnopithecus frontatus, 12. Hipposiderus doriz. 
2 5 rubicundus. 13. ‘5 sabanus, 
3. = sabanus. 14, Bs coxi. 
| 4, es hosei. 15. Hesperoptenus dorie. 
5 Yi everetti. 16. Kerivoula pusilla. 
6 = maurus var. 17. Taphozous longimanus_ var. 
cristatus. albipennis. 
7. Nasalis larvatus. pe eee fe 
CHIROPTERA (bats). 18. Dendrogale murina. 
8. Cynopterus lucasi. 19. Tupaia mulleri. 
9 ms maculatus. 20. ‘5  pieta. 


10. oe spadiceus. 21: » | montana, 


CHAP. XVII BORNEO, JAVA, AND THE PHILIPPINES 377 


22. Tupaia gracilis, 45. Sciurus atricapillus. 
23. ,,  #1=xmelanura.: 46. 4, «carols. 
mee 4, “minor. 47. ,,  baluensis. 
25. Gymnura rafflesii, var. alba. 48.  ,,  rufoniger, var. pluto. 
26. Hylomys suillus, var. dorsalis, 49. ,, ° vittatus, var. dulitensis. 
27. Crocidura Krooni. 50. 4, . nigrovittatus, var. 
28. - hosel. orestes, 
29. a baluensis. oi. - brooke. 
30. a foetida. 52, .-;, - ‘jentinki, 
Bt. - dorie. | 53. simus. 
32. Chimarrogale phaeura. 54, Nannosciurus whitehead. 
CARNIVORA. 55. Mus infraluteus. 
33. Helictis everetti. 56. ,, baluensis. 
34. Mustela flavioula, var. henrict, 5%- >» whiteheadi. 
35. Hemigale hosei. 58. ,, beodon. 
36. Felis badia. | 59. 4, alticola. 
7 60. ,, ochraceiventer. 
_ RopENTa. 61. margarette. 
a7. Petaurista thomasi. f 62. Chiropodomys major. 
38. Sciuropterus thomsoni. 63. pusillus. 
39. ,,__ hosel. 64. Trichys lipura. 
40. Rhithrosciurus macrotis. 
41 Sciurus hosei. UNGULATA, : 
42. ,, insignis, var. diversus. 65. Sus verrucosus, var. borneensis. 
43. ,,  everetti. CETACEA. 
44. 4, pryeri. 66. Sotalia borneensis. 


This extensive list of peculiar species does not necessarily 
imply that the separation of the island from the continent 
is of very ancient date, for its area is so great, and so much 
of the once connecting land is covered with water, that the 
amount of speciality is hardly, ifat 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 re- 

presentative species closely allied to those of the surround- 
‘ing countries, such as the tailed monkeys and the numer- 
ous squirrels. These relationships, however, are best seen 
among the birds, which have been more thoroughly 
collected and more carefully studied than the mammalia. 


378 ISLAND LIFE PART II 


Birds. Sega 490 species of birds are now known to 
inhabit Borneo, of which 415 species are land-birds.!| One 
hundred and twenty-six species are supposed to be peculiar 
to the island, and of these about one-half are either represen- 
tative 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 having their representative forms in the 
Philippine Islands or Celebes. But there is another group 
of eight species whose 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 are 
in many cases very slightly differentiated from their allies, 
are indicated by a single star (*). The species in italies 
belong to genera which are peculiar to Borneo. 


List oF BIRDS WHICH ARE SUPPOSED TO BE PECULIAR TO BoRNEO.? 
TETRAONID& (Grouse, &c.). 15. Heteroscops lucie. 
. *Rhizothera dulitensis. 16. *Syrnium leptogrammicum. 


1 

2. Arboricola hyperythra. PopARGID (Frogmouths). 

3. Heematortyx sanguiniceps. i¥. ““Batrachost ‘lk 

4, Caloperdix borneensis, WP oer mirambhan eaom ee 
18. oe harterti. 


PHASIANID& (Pheasants). 


: ALCEDINID# (Kingfishers). 
5. Acomus pyronotus. ; : 
6. Lobiophasis bulweri. 19. *Carcineutes melanops. 
7. Polyplectron schliermacheri. TROGONID# (Trogons). 
8. “Argusianus grayi. 20. Harpactes whiteheadi. 
FALconip& (Hawks, &c.). 21. »,  diardi, | 
9. *Accipiter rufotibialis. 22.* 4,  dulitensis. 
10. *Spilornis raja. CucuLIp& (Cuckoos). 
11. *Baza borneensis. 23. Heterococcyx neglectus. 
12. Microhierax latifrons. 24, *Khopodytes borneensis. 
BuBONIDS (Owls). 25. Carpococcyx radiatus. 
13. Scops mantananensis. CAPITONID (Barbets). 
14, ,, + brookei. 26. Calorhamphus fuliginosus. 


1 In the first edition of this work the numbers were 400 and 340, 
showing the great increase of our knowledge during the last twenty years, 
chiefly owing to the researches of Mr. A. H. Everett in Sarawak and Mr. 
John Whitehead in North Borneo and the great mountain Kina Balu. 

2 In this edition the arrangement of the families is greatly altered so as 
to correspond with the new catalogues of birds in the “British Museum so 
far as published. 


- OMAP. xvII BORNEO, JAVA, AND THE PHILIPPINES 379 


27. *Chotorhia chrysopsis. 
28. re monticola. 
29. Mesobucco eximius. 
294, Cyanops pulcherrima. 


Picip& (Woodpeckers). 
30. *Jyngipicus aurantiiventris. 
31. ki picatus. 
32. Ree auritus. 
33. *Micropternus badiosus. 


EurRyYL@MID& (Gapers). 


34. Calyptomena whitehead. 
35% hosei. 


Pirrrpm (Ground Thrushes). 
36. Pitta berte. 
a) 4,  arcuata. 
cet ys ©«= audi. 
39. * ,,  usheri. 
40. * ,, granatina. 
41. * ,, schwaneri. 


CorvID& (Crows). 


42. *Dendrocitta cinerascens. 
43. Cissa jeffreyi. 
44, *Platysmurus aterrimus. 


PLOCEIDA (Weavers). 


45. Uroloncha fuscans. 

46. Chlorura borneensis. 

47. Ki hyperythra. 
Dica1pD& (Flower-peckers). 

48. *Zosterops squamifrons. 


49. *Diceum monticolum. 
eee ys =| pryeri. 


51. * Prionochilus xanthopygius. 


52. * He everetti. 


NECTARINEID# (Sun-birds). 


53. Arachnothera julie. 
54, everetti. 
55. Bethe throptes simplex. 


MuscicaPip& (Flycatchers). 


56. **Hemichelidon cinereiceps. 
57. Gerygone salvadorii. 

58. ‘ Rhinomyias gularis. 

59, * se ruficrissa. 

60. Cryptolopha schwaneri, 

61. montis. 

62. *Stoparola cerviniventris, 
63. Siphia ceruleata. 

64.  .,, ~ beccariana. 

S.  ,,  elopurensis. 


66. Siphia obscura. 


67. - ,, » everetti. 

68. ,,  nigrigularis. 

CAMPOPHAGID# (Caterpillar- 
catchers). 


69. Chlamydocheera jeffreyi. 
70. *Artamides normani. 
71. Pericrocotus cinereigula. 
1a ie montanus. 


Dicrurip& (Drongo-shrikes). 
3. *Chibia borneensis. 
LANIID# (Shrikes). 
74. Pityriasis gymnocephala. 
75. *Hyloterpe hypoxantha. 
76, . whiteheadi. 
ORIOLIDA (Orioles). 


77. Oriolus consobrinus. 
78. v5. CyuOset 
(9.4.7. oo Sulmeratus, 


PARID& (Tits). 
80. Parus sarawakensis. 
81. *Dendrophila corallipes. 


BRACHYPODIDZ (Bulbuls). 
82. *Hemixus connectens. 
83. Criniger diardi. 

84, * 4, >) Itierigsys: 
85. Tricophoropsis typus. 
86. Oreostictes leucops. 
87. Rubigula montis. 


“I 


a paroticalis. 

89. Chloropsis kinabaluensis. 
90. = viridinucha. 
91. 5 flavocincta. 


TIMELIID& (Babbling Thrushes). 


92. *Garrulax schistochlamys. 

93. Rhinocichla treacheri. 

94, Allocotops calvus. 

95. **Stachyris borneensis. 

96. Cyanoderma bicolor. 

97. Chlorocharis emiliz. 

98. Androphilus accentor. 

99. Malacopterum cinereocapillum. 
100. erythrote. 
101. **Staphidia everetti. 

102. * Herpornis brunnescens. 
103. *Mixornis borneensis. 
WN ae ord montanus. 
105, “Tordinus canicapillus. 
106. ie kalulongae. 


CC 


379a ISLAND LIFE PART II 


107. Turdinus §atrigularis. 116. **Geocichla aurata. 

108. - tephrops. TA. ys everetti. 

109. Ptilopyga rufiventris. 118. **Myiophoneus borneensis. 

110. a leucogrammica. 119. Brachypteryx erythrogyna. 

111. *Corythocichla crassa. 120. Copsychus niger. 

112. *Turdinulus exsul. 121. *Cittocincla suavis. 

113. Ornithocichla whiteheadi. ib Ps stricklandi. 

123. Hydrocichla ruficapilla. 

Turpip#& (Thrushes). 124. *Henicurus borneensis. 

114. **Cettia oreophila. 125. *Phyllergates cucullatus. 

115. *Merula seebohmi. 126. Burnesia superciliaris. 


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 27 per cent., and the difference may 
fairly be imputed to the greater proportion of slightly 
modified representative species due toa 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 
Hematortyx, a crested partridge ; Lobiophasis’ a pheasant 
hardly distinct from Euplocamus; Heteroscops, an owl; 
and Heterococcyx, a peculiar cuckoo. 

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 about one-third peculiar 
species of mammalia and more than one-fourth peculiar 


1 These are Allocotops, Chlorocharis, and Ptilopyga, among the 
Timeliide ; Tricophoropsis and Oreoctistes among the Brachypodide ; 
Chlamydochera among the Campophagide, and Pityriasis, the bare-headed 
shrike. 


CHAP. xvII BORNEO, JAVA, AND THE PHILIPPINES 380 
species of land-birds, teaches us that the possession of the 
power of flight affects but little the distribution of land- 
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 moderate watery barriers, to as great an extent as 
mammalia. 

The Affinities of the Bornean Fauna—The animals of 
Borneo exhibit an almost perfect identity in general 
character, and a close similarity in species, with those of 
Sumatra and the Malay Peninsula. So great is this 
resemblance that it is a question whether it might not be 
quite as great were the whole united; for the extreme 
points of Borneo and Sumatra are 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. 


Ss At 2 gle 


381 ISLAND LIFE PART II 


JAVA. 


The rich and beautiful island of Java, interesting alike 
to the politician, the geographer, and the naturalist, is 
more especially attractive to the student of geographical 
distribution, because it furnishes him 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 
volcanic 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 te 
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 1t over as a less intetest- 
ing island than Borneo or Sumatra. Its mammalia (ninety 
species) are much less numerous than those of Borneo, 
and 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 also less rich, having only 300 species,’ 

1 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 quite different.’ ” 


2 As there is no recent account of the fauna of Java, the figures here 
given may require some modification. 


CHAP. xvII BORNEO, JAVA, AND THE PHILIPPINES 382 
of which about forty-five are peculiar, and only one 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 Java and that of the other 
great Malay Islands.—Comparing the fauna of Java with 
that which may be called the typical Malayan fauna as 
exhibited in Borneo, Sumatra, and the Malay Peninsula, 
we 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 occurring at 
least in two, and for the most part in all three, of the 
Malay countries, which are yet absent from Java. Most 
of these are large and conspicuous forms, such as jays, 
gapers, bee-eaters, woodpeckers, 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 species; 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 


383 ISLAND LIFE PART II 


had a history of its own, quite distinct from that of the 
other portions of the Malayan area. 

Special Relations of the Javan Fauna to that of the Asiatic 
Continent.—These relations are indicated by comparatively 
few examples, but they are very clear and of great im- 
portance. Among mammalia, the genus Helictis is found 
in Java, but in no other Malay country except a recently 
discovered species in Borneo. But it inhabits also North 
India ; while two species, Lhinoceros javanicus and Lepus 
hua “gost, 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 Tenas- 
serim, but none of them occurring in Malacca, Sumatra, 
or Borneo. There is also the very distinct Javanese 
peacock (Pavo muticus), which inhabits only Java and the 
Indo-Chinese countries, reaching Perak in the northern 
part of 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 


- CHAP. XVII BORNEO, JAVA, AND THE PHILIPPINES 384 


and modification of species must have been the repeated 
changes from cold to warm, and from warm to cold con- 
ditions, 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 
ean sketch out a series of not improbable changes which 
may have brought about the existing relations of Java and 
Borneo to the continent. 

Past Geographical Changes of Java and Borneo.— 
Although Java and Sumatra are mainly volcanic, they are 
by no means wholly so. Sumatra possesses in its great 
mountain masses ancient crystalline rocks with much 
granite, while there are extensive Tertiary deposits of 
Kocene 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 
depression would probably extend to considerable parts of 
Sumatra and Borneo, so as to reduce them all to a few 
small islands. At some later period a gradual elevation 
occurred, which ultimately united the whole of the islands 
with the continent. This may have continued til] the 
glacial period of the northern hemisphere, during the 


1 “*On the Geology of Sumatra,” by M. R. D. M. Verbeck. Geological 
Magazine, 1877. 


385 | ISLAND LIFE PART II 
severest part of which a few Himalayan species of birds 
and mammals may have been driven southward, and 
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 the 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.1 

In my Geographical Distribution of Animals, Vol. L, 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 climate on the migration 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 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 

1 Pitta megarhynchus (Banca) allied to P. brachywrus (Borneo, Sumatra, 


Malacca); and Pitta bangkanus (Banca) allied to P. sordidus (Borneo and 
‘ Sumatra). 


‘CHAP. xvir_ BORNEO, JAVA, AND THE PHILIPPINES 386 


and Borneo, from which they could not return owing to the 
subsequent isolation of those islands by subsidence, seems 
to be a cause exactly adapted to produce the kind 
and amount of affinity between these distant countries 
that actually exists. 


« THE PHILIPPINE ISLANDS. 


During the ten years that have elapsed since the issue 
of the second edition of this work a succession of collectors 
has visited the Philippines and have added very largely 
to our knowledge of the fauna of these rich and interest- 
ing islands, especially as regards the higher animals. In 
the mammalia the additions have been so large that the 
number of terrestrial species has been more than 
doubled, while the aerial bats have been increased in a 
much smaller proportion. 

The following list, embodying the most recent dis- 
coveries, has been kindly furnished me by Mr. W. Eagle 
Clarke, of the Edinburgh Museum. The Palawan group 
is excluded as being more allied to Borneo. 


LIST OF THE TERRESTRIAL MAMMALIA OF THE PHILIPPINES. 
PRIMATES or QUADRUMANA. 


1. Hylobates leuciscus. A widespread species of Gibbon. Sulu Is., 
not in the Philippines proper. 

2. Macacus cynomolgus. 

3. ie maurus. Celebes, Bouton. 

4. Cynopithecus niger. The almost tailless ape of Celebes. Perhaps 
introduced. 

5. Tarsius philippensis. Allied to the spectre lemur of Borneo, &c. 


INSECTIVORA. 


6. Galeopithecus philippensis. A flying lemur. Mindanaoand other Is. 
7. Tupaia everett. 

8. Crocidura luzoniensis. Luzon. 

9 

0 


: 9 grayt. Luzon. 
10. ys caerulea. Sulu. 
CARNIVORA. 


11. Mustela henrici, var. leucotis. Sulu. 

12. Viverra tangalunga. | 

13. Paradoxurus philippinensis. 

14. Felis bengalensis, var. minuta. Negros, Panay, Cebu. 


387 ISLAND LIFE PART II 


RoOMENTIA. 
15. Sciuropterus nigripes. Philippines and Palawan. 
16. Sciwrus philippinensis. Mindanao, Basilan. 


a7: »,  mindanensis. Mindanao. 

18 5»  samarensis. Samar. 

19. Nannosciwrus concinnus. Mindanao, Basilan. 
20: bs samaricus, Samar. 


21. CELHNOMYS SILACEUS. Luzon. 

22. CRUNOMYS FALLAX. Luzon. 

23. PHLHOMYS CUMMINGI. Luzon, Mindoro. e 
24, PALLIDUS. Luzon. 

25. RHYNCOMYS SORICOIDES. Luzon. 

26. CHROTOMYS WHITEHEADI. Luzon. 

27. Mus everetti. 

28. 5 cueonicus.. Laizon. 

29. ,, mindorensis. Mindoro, Negros. 

30. ,, chrysocomus. Luzon, Celebes (?) 

31. ,, ephippium, var. negrinus. Luzon, Negros. 
o2. ,, castaneus. 

33. BATOMYS GRANTI. Luzon. 

34. CARPOMYS MELANURUS. Luzon. 

35. PHAEURUS Luzon. 

36. CRATEROMYS SCHADENBERGI. Luzon. 


UNGULATA. 
37. Sus celebensis, var. philippinensis. 
38. ,, minutus. Mindanao. 
39. Tragulus nigricans. Balabac. 
40. Cervus philippinus. Luzon. 


41. » nigricans. 

42. ,,  alfredi. Samar, Leite. 

43: 4, steers. . Basilan: 

44, Buffelus mindorensis. Mindoro. <A small buffalo somewhat like 
the Anoa. 


N.B.—The two domestic rats of Europe have been omitted from this 
list as certainly introduced. 

The bats (Chiroptera), being very numerous and of little 
popular interest, are also omitted. There are 35 species 
now discovered and they belong to sixteen genera. Six- 
teen of the species and one genus are peculiar to the 
Philippines. Of the 44 true land mammals no less than 
33 are peculiar (indicated by italics and capitals) or exactly 
three-fourths of the whole. This is a very large amount of 
speciality as compared with Borneo, which has only one- 
third peculiar. There are also eight peculiar genera (in- 
dicated by small capitals), but these are all among the 
rodents, which are perhaps less known in many of the sur- 
rounding countries. 

Birds.—The late Marquis of Tweeddale made a special 


a 
titi 
= ae a OO i a a 


CHAP. xvII BORNEO, JAVA, AND THE PHILIPPINES 388 


study of Philippine birds, and in 1873 published a 
catalogue in the 7'ransactions of the Zoological Society (Vol. 
IX. Pt. 2, pp. 125-247). But since that date large 
collections have been made by Everett, Steere, Whitehead, 
and other travellers, the result of which has been to more 
than double the known species, and to render the ornitho- 
logical fauna an exceedingly rich one. Many of the Malayan 
genera which were thought to be absent when the first 
edition of this work was published have since been dis- 
covered, among which 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. Such are Meiglyptes,a genus of 
woodpeckers; Phcenicophaes, a remarkable genus of 
cuckoos; the long-tailed paroquets, Paleeornis; and all the 
genera of Barbets except Xantholema. There are also 
many genera allied to Timalia and Ixos; the mynahs, 
Gracula; the long-tailed flycatchers, Tchitrea; the fire- 
backed pheasants, Euplocamus; the argus pheasants, and 
many others. 

The following tabular statement will illustrate the rapid 
growth of our knowledge of the birds of the Philippines, 
as in the case of the mammals excluding the Palawan 
group :— : 


Land-birds.|Water-birds.; Total. 


Lord Tweeddale’s Catalogue (1873) ......... 158 60 218 


Mr. Wardlaw Ramsay’s List (1881) ......... | =. 265 75 340 


Messrs. Worcester and Bourn’s List jie 438 88 526 1 


Mr. W. Eagle Clarke has given me the latest figures 
by including all the new species discovered up to the 
present year (1901), as follows :— 


Land Birds ... 442 species, of which 312 are peculiar. : 
Water Birds.. 97  ,, a 6 re 


We have here, still more pronounced than in the case 
of Borneo, the remarkable fact of the true land-birds 


1 Proc. U. S. Nat. Museum, vol. xx. (1898), pp. 549-625. 


889 ISLAND LIFE “ PART IT 


presenting a larger amount of speciality than the land 
mammals ; for while a little less than three-fourths of the 
birds are peculiar, only five-eighths of the mammals are 
so; and as physical isolation has certainly not been so 
effective in the former group (the birds), we learn that 
such isolation is not so important a factor in the pro- 
duction of new species as it is usually supposed to be. 

The general character of the fauna of this group 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 were 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 fact 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 1s supported by direct evidence; for I am 
informed by Mr. Everett, who has made extensive explora- 
tions in the islands, that almost everywhere are found 
large tracts of elevated coral-reefs, containing shelis 
similar to those living in the adjacent seas, an indisputable 
proof of very recent elevation. 

Concluding Remarks on the Malay Islands.—This com- 
pletes our sketch of the great Malay islands, the seat of 
the typical Malayan fauna. It has been shown that the 
peculiarities presented by the individual islands may be all 


CHAP. XVII aati JAVA, AND THE PHILIPPINES 390 


sufficiently well explained by a very simple and com- 
paratively unimportant series of geographical 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, 
appears 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 which offer features of special interest, and which 
will complete our illustrative survey of recent continental 
islands. 


CHAPTER XVIII 
JAPAN AND FORMOSA 


Japan, its Position and Physical Features—Zoological Features of Japan— 
Mammalia—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. 


JAPAN, 


THE Japanese Islands occupy a very similar position on 
the eastern shore of the great Kuro-Asiatic continent to 
that of the British Islands on the western, except that 
they are 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, the 
volcanic peak of Fusiyama being 14,177 feet high ; while 
their geological structure is very complex, their soil 
extremely fertile, and their vegetation in the highest 
degree varied and beautiful. Like our own islands, too, 
they are connected with the continent by a marine bank 
less than a hundred fathoms below the surface—at all 
events towards the north and south; but in the inter- 
vening space the Sea of Japan opens out to a width of 
six hundred miles, und in its central portion is very deep, 


PEKING e\_ 


d 


sh 

, 

| 

Hi | 


_—— SSS 
——————— ———————————— 
eee 


———————SLSSSSESSSSSq 
e ce 
= — ey 
S=S=——————Haaysy SSS 
_————d EEE 
SSS e—ee—E——e—E—E—E—EEeeEEEod 
———_$_— SS SSSSS>SS>S>S>"*_—_SSS—_SS=S=S=s 


CANTON 
SSS SS 


MAP OF JAPAN AND FORMOSA (with depths in fathoms). 


Light tint, sea under 100 fathoms. Medium tint, under 1,000 fathoms. Dark tint, over 
1,000 fathoms. The figures show the depth in fathoms. 


393 ISLAND LIFE PART II 


and this may be,an indication that the connection between 
the islands and the continent is of rather 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-five miles 
wide, forms a connection with Amoorland in about 52° N. 
Lat. A southern warm current flowing a little to 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 
tropical vegetation and more varied forms of life than are 
found at corresponding latitudes in China. 

Zoological Features of Japan.—As we might expect from 
the conditions here sketched out, Japan exhibits in all its 
forms of animal life a close general resemblance to the 
adjacent 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 different 
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 alliesin China but occur again only in Northern India or 
the Malay Archipelago. There is also a slight American 
element in the fauna of Japan, a relic probably of the 
period when a land communication existed between the 
two continents over what are now the shallow seas of 
Japan, Ochotsk, and Kamschatka. We will now proceed 
to examine the peculiarities and relations of the fauna. 

Mammalia.—The mammalia of Japan at present known 
are forty-two in number; not very many when compared 
with the rich fauna of China and Manchuria, but contain- 
ing monkeys, bears, deer, wild goats, and wild boars, as 
well as foxes, badgers, moles squirrels, and hares, so that 
there can be no doubt whatever that they imply a land 
connection with the continent. No complete account of 
Japan mammals has been given by any competent 
zoologist since the publication of Von Siebold’s Fauna 


CHAP. XVIII JAPAN AND FORMOSA 394 


Japonica in 1844, but by collecting together most of the 
scattered observations since that period the following list 
has been drawn up, and has been corrected for the present 
edition by Mr Oldfield Thomas of the British Museum. 
The species believed to be peculiar to Japan are printed 
in italics. ‘These are very numerous, but as Corea and 
Manchuria (the portions of the continent opposite Japan) 
are comparatively little known, their number may be 
somewhat diminished. 


LIST OF THE MAMMALIA OF THE JAPANESE ISLANDS. 


1. Macacus speciosus. A monkey with rudimentary tail and red face, 
allied to the Barbary ape. It inl alits the island of Niphon up to 
41° N. Lat., and has thus the most northern range of any living 
monkey. 

2. Pieropus dasymallus. A peculiar fruit-bat, found in Kiusiu Island 
only (Lat. 33° N.), and thus ranging further north of the equator 
than any other species of the genus. 

38. Rhinolophus ferrum-equinum. The great horse-shoe bat, ranges from 
Britain across Europe and temperate Asia to Japan. It is the &. 
nippon of the Fauna Japonica according to Mr. Dobson’s Monograph 
of Asiatic Bats. 

4. R. minor. Found also in Burma, Yunan, Java, Borneo, &c. 

5. Pipistrellus pipistrellus. From Britain across Europe and Asia. 

6. P. abramus. Also in India and China. 

7. P. noctula. From Britain across Europe and Asia. 

8. P. molossus. Also in China. 

9. Myotis macrodactylus. 

0. Miniopterus schreibersii. Philippines, Burma, Malay Islands.» This 
is Vespertilio blepotis of the Fauna Japonica. 

11. Talpa wogura. Also in China. Closely resembles the common mole 
of Europe, but has four incisors instead of six in the lower jaw. 

12. Talpa mizura. Giinth. Allied to 7. ewropwa. 

13. Urotrichus talpoides. A peculiar genus of moles confined to Japan. 
An American species has been named Urotrichus gibbsii, and Mr. 
Lord after comparing the two says that he ‘‘can find no difference 
whatever, either generic or specific. In shape, size, and colour, they 
are exactly alike.” But Dr. Giinther (P. 7. S. 1880, p. 441) states 
that U. gibbsii differs so much in dentition from the Japanese 
species that it should be placed in a distinct genus, which he calls 
Neurotrichus. 

14. Dymecodon pilirostris. True. Yeddo. Peculiar genus of mole, allied 
to Urotrichus. 

15. Crocidura murina. <A shrew, found also in India and Malaya. 

16. Sorex dzi-nezumi. 

17. S. wmbrina. 

18. Chimarrogale platycephala. Water shrew, related to Himalayan and 

Bornean species. 


D D 


395 ISLAND LIFE PART II 


19, Ursus arctos. var. <A peculiar variety of the European brown bear 
which inhabits also Amoorland and Kamschatka. It is the Ursus 
JSerox of the Fauna Japonica. 

20. Ursus japonicus. <A peculiar species allied to the Himalayan and For- 
mosan species. Named U. tibetanus in the Fauna Japonica. 

21. Meles anakuma. Differs from the European and Siberian badgers in 
the form of the skull. 

22. mi ita brachyura. A peculiar martin found also in the Kurile 

slands. 

23. Mustela melampus. The Japanese sable. 

24, Putorius Sibiricus. Also Siberia and China. This is the Ml. ctatsi of 
the Fauna Japonica according to Dr. Gray. 

25. Lutra vulgaris. 

26. Pusa lutris. The sea-otter of California and Kamschatka. 

27. Canis hodophylax. The Japanese wolf. 

28. Vulpes japonica. A peculiar fox. Canis vulpes of Fauna Japonica. 

29. ee procyonoides. The racoon-dog of N. China and Amoor- 
land. 

30. Lepus brachyurus. A peculiar hare. 

31. Sciwrus dis. A peculiar squirrel. 

32, Pteromys leucogenys. The white-cheeked flying squirrel. 

33. Sciuropturus momoga. Peculiar. 

34. Myoxus japonicus. A peculiar dormouse. MM. elegans of the Fauna 
Japonica ; WM. javanicus, Schinz (Synopsis Mammalium, i. p. 580). 

35. Mus argenteus. China. 

36. Mus molossinus. 

37. M. nezumi. 

38. MM. speciosus. 

39. Microtus sp. <A vole of doubtful affinities. 

40. Cervus sika. A peculiar deer allied to C. pseudaais of Formosa and 
C. mantchuricus of Northern China. 

41. Nemorhedus crispa. A goat-like antelope allied to NV. Sumatranus of 
Sumatra, and VV. Swinhoet of Formosa. 

42. Sus leucomystax. A wild boar allied to S. taevanus of Formosa. 


We thus find that no less than twenty-eight out of the 
forty-two Japanese mammals are peculiar, and if we omit 
the aérial bats (nine in number), as well as the marine 
sea-otter, we shall have remaining only thirty-two strictly 
land mammalia, of which twenty-six are peculiar, or 
nearly five-sixths of the whole. Nor does this represent 
all their speciality; for we have a mole superficially 
resembling but quite distinct from an American species ; 
another mole forming a peculiar genus; an antelope 
whose nearest allies are in Formosa and Sumatra, and a 
water-shrew whose nearest allies are in the Himalayas 
and Borneo. The importance of these facts will be best 
understood when we have examined the corresponding 
affinities of the birds of Japan. 


a tes tM — 


a 


CHAP. XVIII. JAPAN AND FORMOSA 396 

Sirds.—Owing to the recent pesesholis of some Bnglish 
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, which is less than might be expected 
considering the highly favourableconditions 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 whole, are now considered to be pecular to Japan 
proper ; while seventeen more are peculiar to the various 
outlying small islands constituting the Bonin and Loo Choo 
groups. Even of these, six or seven are classed by Mr. See- 


bohm as probably sub-species or shghtly 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 British 
species that the difference is only perceptible to a trained 
ornithologist. The following list of the land-birds common 
to Britain and Japan is very interesting, when we consider 
that these countries are separated by the whole extent of 
the European and Asiatic continents, or by almost exactly 
one-fourth of the circumference of the globe :— 


LAND Brrps CoMMON 'Tro GREAT BRITAIN AND JAPAN.! 


(Hither Identical Species or Representative Sub-species. ) 


0 Regulus cristatus sub-sp. orientalis. 

0 Parus palustris sub-sp. japonicus. 

ne Parus ater sub-sp. pekinensis. 

memeeome tailed tit .............+. Acredula caudata (the sub-sp. rosea is 
British). 


1 Extracted from Messrs. Blakiston and Pryer’s Catalogue of Birds of 
Japan (Ibis, 1878, p. 209), with Mr. Seebohm’s additions and corrections 
in his Birds of the Japanese Empire 1890. Accidental stragglers are not 
reckoned as British birds. 


BD 2 


397 ISLAND LIFE PART II 


5. Common creeper ...):.5... Certhia familiaris. 
B.D eRCl i hak stow on Sitta ewropea sub-sp. amurensis. 
f= ADEE CLOW 6S orden wee Corvus corone. 
Ou? arbetwe Ker yi ces tata asus Nucifraga caryocatacies. 
Os ME niin. Be ccdedae Pica caudata. 
10. Pallass’ grey shrike ...... Lanius excubitor sub-sp, major. 
2 Rae CS es) Aas pied iek epee Ampelis garrulus. 
12: Grey ‘wagtail 1.000.006. Motacilla boarula sub-sp. melanope. 
135; Aipmne PU 66x sevinc e558 Anihus spinoletta sub-sp. japonicus. 
PA VIBE sen hynes oe chcew cern Alauda arvensis sub-sp. japonica. 
15. Common hawfinch ...... Coceothraustes vulgaris. 
16. Common Crossbill ......... Loxia curvirostra. 
Ayes Rec Cn katte se PL Fringilla spinus. 
18: Mealy redpole ... 2224... be linaria. 
HD): DramBUAS, oi. es a0 ces ae a montifringilla. 
20. Tree sparrow ............... Passer montanus. 
21: Reed bunting’. xs ie.sisct Emberiza scheniculus sub.sp. palustris, 
22. Rustic bunting .....:...... wt rustica, 
23. Snow bunting............... oh nivalis, 
24. Chimney swallow .......... Hirwndo rustica sub-sp. guttwralis. 
Go. wand: mianbin ticct iad Cotyle riparia. 
26. Great spotted woodpecker Pticus major sub-sp. japonicus. 
27. Lesser spotted woodpecker ,, minor. 
Moe WV MERON tcc celvcsee sats Jynx torquilla. 
Bs IMO OG a si i Wise lala nin dpi ot Upupa epops. 
30. Blue rock pigeon ......... Columba livia. 
ae GO jos cinery. ete civks tis Cuculus canorus. 
32. Kingfisher ..... Pater hte Alcedo ispida sub-sp. bengalensis. 
= i ed 2 eae Bubo maximus. 
SA, MOMMY OW. abe) snc oovus Surnia nyctea. 
35. Long-eared owl ............ Strix otus. 
36. Short-eared owl ............ 5, brachyotus. 
BF OOPS OWly i cckey Sond ccvelebs Scops scops. 
Boe POP FAleON ioc. ncueencos Faleo gyrfalco. 
39. Peregrine falcon.....:...... » peregrinus. 
BO) “TIOB DY ak ses bi 5is enon tee ae », subbuteo. 
#1. Blerhiat clus tain at Falco cesalon. 
BA Mpeired ch ct. acts ave yet — Tinnunculus alaudarius sub-sp. japonicus. 
BS NOBBERY, «pile a olexeasc cheer nar Pandion halidctus. 
44, Honey-buzzard ............ Pernis apivorus. 
45. White-tailed eagle......... _ Halidéetus albicilla. 
46, Golden’ eagle: saci sini as sc Aquila chrysdctus. 
47. Common buzzard ......... Luteo vulgaris sub-sp. plumipes. 
48. Hen-harrier ...... eisth ie Circus cyaneus. 
49. Marsh-harrier ...i..i.:¢.%.: » eruginosus. 
50; Gios-awk)) divca buchos Astur palumbarius. 
51. Sparrow-hawk ......... .. Accipiter nisus. 
URS fg gf | Ree ee Ey Tetrao mutus. 
538,. Common quail? )..0../.44 Coturnix communis. 


But even these fifty-three species by no means fairly 


represent the amount of resemblance between Britain and 


CHAP. XVIII JAPAN AND FORMOSA 398 


Japan as regards birds; for there are also thrushes, robins, 
stonechats, wrens, hedge-sparrows, sedge-warblers, jays, 
starlings, swifts, goatsuckers, and some others, which, 
though distinct species 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 Himalayan rather than 
Chinese, and thus afford us an interesting problem 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 (7'reron 
sicboldt)—has no close ally nearer than Burmah and the 


Himalayas. In the following list the affinities of the species 


are indicated wherever they have been ascertained :— 


LIsT OF THE SPECIES OF LAND BIRDS PECULIAR TO JAPAN. 


1. Accentor rubidus. Nearly allied to our hedge-sparrow, and less closely 
to the Central Asian A. vmmaculatus. 

(la. Hypsipetes amaurotis. Migrates to the Corea, otherwise peculiar. ) 

Zosterops japonica, An Oriental genus. Allied to Chinese species. 

. Lusciniola pryert. 

Garrulus japonicus. Allied to the Siberian and British jays. 

. Fringilla kawarahiba. Allied to the Chinese greenfinch. 

Emberiza ciopsis. Allied to the E. Siberian bunting £. cioides, of 

which it may be considered a sub-species, 

. Emberiza yessoensis. A distinct species. 

i personata. A sub-species of EH, spodocephala. 

. Gecinus awokera, A distinct species of green woodpecker. 

. Picus namiyet. Allied to a Formosan species. 

. Treron sieboldi. Allied to T. sphenura of the Himalayas, and to a 

Formosan species. 

12. Carpophaga ianthina. A distinct species of fruit-pigeon. 

13. Bubo blakistont. Allied to a Philippine eagle-owl. 

14. Scops semitorgues. A distinct species 

15. Phasianus versicolor. A distinct species. 

16. ie semmeringt. A distinct species. 


im G9 bo 


bt 
MH SOCONT DMN 


af. ‘ scintillaus. A sub-species of the last. 


In addition to the above, the large number of seventeen 
peculiar species in the outlying Bonin and Loo Choo 


Islands is an interesting feature of Japanese ornithology. 


399 ISLAND LIFE PART IL 


The comparative remoteness of these islands, their mild 
sub-tropical climate and luxuriant vegetation, and perhaps 
the absence of violent 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 adapted to the new environment. 

Japan Lirds Recurring in Distant Areas.—The most 
interesting feature in the. ornithology of Japan 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 China, 
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 (Garrulus japonicus), whose 
near ally (G. glandarius) inhabits Europe only, at a 
distance of 3,700 miles. But even more extraordinary are 
the following non-peculiar species :—Spizaetus orientalis, a 
crested eagle, inhabiting the Himalayas, Formosa, and 
Japan, but unknown in Southern or Eastern China; Ceryle 
guttata, a spotted kingfisher, almost confined to the 
Himalayas and Japan, though occurring rarely in Central 
China; and fTaleyon 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 which islands afford 
both for species which elsewhere live further south 
(Halcyon coromanda), 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 very 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 Ceryle 
guttata formerly ranged from the Himalayas to Japan, and 
has now almost died out in the intervening area owing to 
geographical and physical changes, a subject which will be 
better discussed when we have examined the interesting 
fauna of the island of Formosa. 


CHAP. XVIII JAPAN AND FORMOSA 400 


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 Geographical Distribution of Animals 
(Vol L., pp. 227-231), and they sufficiently agree with the 
birds and mammalia in showing a mixture of temperate 
and tropical forms with a considerable proportion of 
peculiar species. Owing to the comparatively easy passage 
from the northern extremity of Japan through the 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 Japan was finally separated from the 
continent. How long ago this separation took place we 
cannot of course tell, but we may be sure it was much 
longer than in the case of our own islands, and therefore 
probably in the earlier portion of the Pliocene period. 


FORMOSA. 


Among recent continental islands there is probably none 
that surpasses in interest and instructiveness the Chinese 
island named by the Portuguese, Formosa, or “The 
Beautiful.” Till the middle of the 19th century 1t was a 
terra incognita to naturalists, and we owe much of 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 spare time and 
energy to the study of natural history, more especially of 
the two important groups, birds and mammals ; and by 
employing a large staff of native collectors and hunters, he 
obtained a very complete knowledge of its fauna. In this 
case, too, we have the great advantage of a very thorough 
knowledge of the adjacent parts of the continent, in large 
part due to Mr Swinhoe’s own exertions during the twenty 


401 ISLAND LIFE PART II 


years of his service in China. We possess, too, the further 
advantage of having the whole of the available materials 
in these two classes collected together by Mr. Swinhoe 
himself after full examination and comparison of specimens ; 
so that there is probably no part of the world Gf we 
except Hurope, North America, and British India) of whose 
warm-blooded vertebrates we possess fuller or more — 
accurate knowledge than we do of those of the coast 
districts of China and its islands.! 

Physical Features of Formosa.—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 the 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, 
perhaps, mark out approximately the last great extension 
of the Asiatic continent, the submergence of which isolated 
these islands from the mainland. 

Animal Life of Formosa.—We are at present acquainted 


1 Mr. Swinhoe died in October, 1877, at the early age of forty-two. His 
writings on natural history are chiefly scattered through the volumes of the 
Proceedings of the Zoological Society and The Ibis; the whole being sum- 
marised in his Catalogue of the Mammals of South China and Formosa (P. 
Z. S., 1870, p. 615), and his Catalogue of the Birds of China and ws 
Islands (P. Z. S., 1871, p. 337). 


CHAP. XVIII JAPAN AND FORMOSA 402 


with 35 species of mammalia, and 128 species of land-birds 
from Formosa, fourteen of the former and thirty-five of the 
latter being peculiar, while the remainder inhabit also 
some part of the continent or adjacent islands This 
proportion of peculiar species is (as regards the birds) a 
very high one for an island which can be classed as both 
continental and recent, and is situated so close to a 
continent, implying that the epoch of separation was 
somewhat remote. It was not, however, remote enough 
to reach back to a time when the continental fauna was 
very different from what it is now, for we find all the 
chief types of living Asiatic mammalia represented in this 
small island. Thus we have monkeys; insectivora ; 
numerous carnivora; pigs, deer, 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 one peculiar 
enus. 

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 proportion 
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 
we shall have frequent occasion to refer to them. 


List OF THE MAMMALIA OF Formosa. (The peculiar species are printed 
in italics ) 


1. Macacus cyclopis. A Rock-monkey more allied to M. rhesus of India 
than to M. sancti-johannis of South China. 

. Pteropus formosus. A Fruit-bat closely allied to the Japanese species. 
None of the genus are found in China. 

. Vesperugo abramus. China. 

. Vespertilio formosus. Black and orange Bat. China. 

.. Nyetinomus cestonii. Large-eared Bat. China, 8S. Europe. 

. Talpa wogura. <A blind Mole. Japan. 


SD oe co bo 


403 ISLAND LIFE PART II 


7. Crocidura murina. Musk Rat. China. 

8. Sorex sp. A Shrew, undescribed. 

9. Erinaceus sp. A Hedgehog, undescribed. 

0. Ursus tibetanus. The Tibetan Bear. Himalayas and North China. 

lL, Helictis subaurantiaca. The orange-tinted Tree Civet. Allied to H. 

nipalensis of the Himalayas more than to H. moschata of China. 

12. Mustela flavigula, var. The yellow-necked Marten. India, China. 

13. Putorius sibirica. China, Siberia. 

14. Felis nebulosa. The clouded Tiger of Himalayas, Siam and Malaya. 

15. Felis viverrina. The Asiatic wild Cat. Himalayas and Malacca. 

16. Felis bengalensis. China, India, Burma. 

17. Viverra malaccensis. Spotted Civet China, India, Malaya. 

18. Paradoxurus larvatus. Gem-faced Civet. China. 

19, Sus taivanus. Allied to the wild Pig of Japan. 

20. Cervulus reevesil. Reeve’s Muntjac. China. 

21. Cervus tevanus. Formosan Spotted Deer. Allied to C. sika of 
Japan. 2 

22. rhe swinhott. Swinhoe’s Rusa Deer. Allied to Indian and Malayan 
species 

23. Ninvihodes swinhoit. Swinhoe’s Goat-antelope. Allied to the species 
of Sumatra and Japan. 

24. Bos chinensis. South China wild Cow. 

25. Mus coxingi. Spinous Country-rat. Burma. 

26. Mus canna. Silken Country-rat. 

27. Mus losea. Brown Country-rat. 

28. Nesokia nemorivagus. India, China. 

29. Sciurus castaneoventris. Chestnut-bellied Squirrel. China and 
Hainan. 

30. S. atrodorsalis. Nepal, China. 

31. Xerus m’clellandi. M‘Clelland’s Squirrel. Himalayas, China. 

32. Sciuroplerus pearsoni. Small Flying Squirrel. Himalayas, Yunan. 

33. P. nitidus. Large Red Flying Squirrel. Indo-China and Malay Is. 

34, Pteromys pectoralis. White-breasted Flying Squirrel. From South 
Formosa. 

85. Lepus sinensis. Chinese Hare. Inhabits South China. 

36. Manis aurita. Scaly Ant-eater. §. China and the Himalayas, 


The 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 
with Chinese species. We have the rock-monkey of 
Formosa allied to the rhesus monkeys of India and 
Burma, not to those of South China and Hainan. The 
tree civet (Helictis subawrantiaca), and the small flying 
squirrel (Sciwropterus kaleensis), are both allied to Hima- 
layan species. Swinhoe’s deer and goat-antelope are 
nearest to Malayan species, as are the red and white- 
breasted flying squirrels ; while the fruit-bat, the wild pig, 
and the spotted deer are all allied to peculiar Japanese 


CHAP. XVIII JAPAN AND FORMOSA 404 


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 their 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 what 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 what 
additional light is thrown upon this subject by an 
examination of the birds. 


LIST OF THE LAND BIRDS PECULIAR TO FORMOSA. 


TETRAONID& (Grouse and Partridges). 


1. Arboricola crudigularis. A Himalayan and Malayan genus of part- 
ridges. 
2. Bambusicola sonorivox. Allied to the Chinese B. thoracica. 


PHASIANID& (Pheasants). 


8. Phasianus formosanus. Allied to P. torquatus of China. 

4. Euplocamus swinhott. A very peculiar and beautiful species allied to 
the tropical fire-backed pheasants, and to the silver pheasant of 
North China. 

CoLUMBID& (Pigeons). 


. Sphenocercus formose. Allied to Malayan species. 
. Sphenocercus sororius. Allied to Malay species and to S. steboldi of 
Japan. No allies of these two birds inhabit China. 


OS Or 


STRIGIDEH (Owls). 
7. Glaucidium pardalota. Closely allied to a Chinese species. 
8. Scops hambroekii. Allied to a Chinese species. 
CAPITONIDA. 


9. Cyanops nuchalis. Allied to C. oortii of Sumatra and C. faber of 
Hainan. 
Picip# (Woodpeckers). 


10. Dendrocopus insularis. Allied to D. leuconotus of Japan and Siberia. 
11. Yungipicus matterst. 


405 ISLAND LIFE PART II 


Corvin (Jays and Crows). 


12. Garrulus taivanus. Allied to G. sinensis of S. China. 

13. Urocissa cerulea.. A very distinct species from its Indian and Chinese 
allies. 

14. Dendrociita formose. Near the Chinese D. sinensis. 


PLOCEID& (Weaver Finches). 
15. Munia formosana. Allied to M. rubronigra of India and Burmah. 


MuscIcAPID& (Flycatchers). 
16. Niltava vivida. Allied to NV. rubeculoides of the Himalayas. 
CAMPEPHAGIDS (Caterpillar Shrikes). 


17. Graucalus rea-pinett. Closely allied to the Indian G. macet. No ally 
in China. 
Dicrurip# (King Crows). 


18. Chaptia brauniana. Closely allied to C. wnea of Assam. No ally in 
China. 
PARIDZ (Tits). 
19. Parus holsti. 
20. P. castaneivente. Allied to P. varius of Japan. 


LIoTRICHID# (Hill Tits). 


21. Liocichla steerti. A peculiar genus of a specially Himalayan family, 
quite unknown in China. 


ORIOLIDZ (Orioles). 


22. Oriolus ardens. Allied to O. traillii of the Himalayas and Tenas- 
serim. 
BRACHYPODID& (Bulbuls). 
224. Pycnonotus taivanus. 
23. Spizixos cinereicapillus. Very near S. semitorques of China. 
24. Hypsipetes nigerrimus. Allied to H. concolor of Assam, not to H. 
macclellandi of China. 


TIMELIID& (Babblers). 


25. Pomatorhinus musicus. Allies in 8. China and the Himalayas. 

26. P. erythrocnemis. Do. do. 

27. Garrulax ruficeps. Allied to G. albogularis of N India and East 
Thibet, not to the species of S. China (G. sanniv). 

28. Dryonastes pecilorhyncha. Allied forms of the Himalayas and China. 

29. Trochalopterum taivanwm. Allied to.a Chinese species. 

30. Alcippe morrisoniana. 

31. Malacias auricularis. Allied to the Himalayan MW. capistrata. 


CrncLID# (Dippers and Whistling Thrushes). 
32. Myiophoneus insularis. Allied to M. horsfieldi of South India. 


TurRDIDs# (Thrushes). 
33. Turdus albiceps. Allied to Chinese species. 
34, Notodela montium. Allied to NV. dewcwra of the Himalayas; no ally 
in China. 


CHAP. XVIII JAPAN AND FORMOSA 406 


This list exhibits to us the remarkable fact that nearly 
half the peculiar species of Formosan birds have their 
nearest allies in such remote regions as the Himalayas, 
South India, the Malay Islands, or Japan, rather than 
in the adjacent parts of the Asiatic continent. Seven 
species have Himalayan allies, and six of these belong to 
genera which are unknown in China. One species has its 
nearest ally in the Nilgherries, and four in the Malay 
Islands ; and of these five, two belong to genera which are 
not Chinese. ‘Two species have their only near allies in 
, Japan. Perhaps more curious still are those cases in which 
though the genus is Chinese, the nearest allied species 
is to be sought for in some remote region. Thus we have 
the Formosan babbler (Garrulax ruficeps) not allied to the 
species found in South China, but to one inhabiting North 
India and East Thibet ; while the black bulbul (Hypsipetes 
mgerrimus) 18 not allied to the Chinese species but to an 
Assamese form. 

In the same category as the above we must place eight 
species which are not peculiar to Formosa, but which are 
Indian or Malayan rather than Chinese, so that they offer 
examples of discontinuous distribution somewhat analogous 
to what we found to occurinJapan. These are enumerated 
in the following list. 


_ Species OF BIRDS COMMON TO FoRMOSA AND INDIA OR MALAYA, BUT NOT 
FOUND IN CHINA. 


1. Siphia superciliaris. The Rufous-breasted Flycatcher of the S.E. 


Himalayas. 

. Haleyoncoromanda. The Great Red Kingfisher of India, Malaya, and 
Japan. 

. Palumbus pulchricollis. The Darjeeling Wood-pigeon of the S.E. 
Himalayas. 


. Turnix dussumiert. The larger Button-quail of India. 

. Spizaetus nipalensis, The Spotted Hawk-eagle of Nepal and Assam. 
. Lophospiza trivirgata. The Crested Gos-hawk of the Malay Islands. 
. Bulaca newarensis. The Brown Wood-owl of the Himalayas. 

. Strix candida. The Grass-owl of India and Malaya. 


onto OU os) bo 


The most interesting of the above are the pigeon and 
the flycatcher, both of which are, so far as yet known, 
strictly confined to the Himalayan mountains and Formosa. 


407 ISLAND LIFE PART II 


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 Fuunas of Hainan, Formosa, and 
Japan.—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 1380 obtained by Mr. Swinhoe), two of 
which areclose allies of Formosan species, while two others 
are identical. We 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 to 
enable us to form an accurate judgment of its relations, 
but 1t 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 
have enabled it to preserve an unusual number of Hima- 
layan and Malayan forms. Japan, almost equally isolated 
towards the south, and having a much greater variety of 
climate as well asa much larger area, possesses a somewhat 
larger number of mammalia than Formosa, and an even 
larger proportion of peculiar species. 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 prevents 


1 Captain Blakiston has shown 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. 


CHAP. XVIII JAPAN AND FORMOSA 408 


the formation of special insular races, such as are almost 
always produced when a portion of the population of a 
species remains for a considerable time completely isolated. 
We thus have 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 Remarks on Recent Continental Islands.—We have 
now briefly sketched the zoological peculiarities of an 
illustrative series of recent continental islands, commencing 
with one of the most recent—Great Britain—in which the 
process of formation of peculiar species has only just 
commenced, and terminating with Formosa, probably one 
of the most ancient of the series, and which 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 whichseparates 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 
species die out and are replaced by others, which quite 
agrees with what the theory of evolution assures us must 
have occurred. On a continent, the process of extinction will 
generally take effect on the circumference of the area of 
distribution, because it is there that the species comes into 
contact with such adverse conditions or competing forms 
as prevent 1t from advancing further. A very slight change 
will evidently turn the scale and cause the species to 
contract its range, and this usually goes on till 1t 1s 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 species 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 


409 ISLAND LIFE PART II 


Asia. (Sce 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 7epresenta- 
“ave forms 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 mtermingling and _ inter- 
crossing of the individuals inhabiting adjacent. localities, 
such variations, being selected in adaptation to divergent 
conditions, would soon form distinct races. But as soon 
as the area is divided into two portions the intercrossing 1s 
stopped, and the usual result is that two closely allied 
races, classed as representative species, become formed. 
Such pairs of allied species on the two sides of a con- 
tinent, or in two detached areas, are very numerous ; and 
their existence 1s only explicable on the supposition’ that 
they are 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 con- 
sequence of the discontinuity, the two sections of the 
parent species became segregated through adaptation into 
distinct races or new species. 

Now, when the division of the area leaves one portion of 
the species in an island, a similar modification of 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 only in 
remote islands, as Japan or Hainan. 


CHAP. XVIII JAPAN AND FORMOSA 410 


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- 
defined 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 problems to the student of distribution. 


CHAPTER XIX 


ANCIENT CONTINENTAL ISLANDS : THE MADAGASCAR GROUP 


Remarks on Ancient Continental Islands—Physical Features of Madagascar 
—Biological Features of Madagascar—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 Madagascar and India—Concluding Remarks on 
‘* Lemuria ”’—The Mascarene Jslands—The Comoro Islands—The Sey- 
chelles Archipelago—Birds of the Seychelles—Reptiles and Amphibia— 
Freshwater Fishes—Land Shells—Mauritius, Bourbon, and Rodriguez— 
Birds—Extinct Birds and their Probable Origin—Reptiles—Flora of 
Madagascar and the Mascarene Islands—Curious Relations of Mascarene 
Plants—Endemic Genera of Mauritius and Seychelles—Fragmentary 
Character of the Mascarene Flora—Flora of Madagascar Allied to that 
of South Africa—Preponderance of Ferns in the Mascarene Flora—Con- 
cluding Remarks on the Madagascar Group. 


WE have now to consider the phenomena presented by a 
very distinct class of islands—those which, although once 
forming part of a continent, have been separated from it at 
a remote epoch when its animal forms were very unlike 
what they are now. Such islands preserve to us the 
record of a by-gone world,—of a period when many of the 
higher types had not yet come into existence and when 
the distribution of others was very different from what 
prevails at the present day. The problem presented by 
these ancient islands is often complicated by the changes 
they themselves have undergone since the period of their 
separation, A partial subsidence will have led to the 


- OHAP. XIx THE MADAGASCAR GROUP 412 
extinction of some of the types that were originally 
preserved, and may leave the ancient fauna in a very 
fragmentary state; while subsequent elevations may have 
brought it so near to the 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 successive 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 phenomena 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, 1s Madagascar, and we shall therefore enter 
somewhat fully into its biological and physical history. 

Physical Features of Madagascar.—This great island 1s 
situated about 250 miles from the east coast of Africa, and 
extends from 12° to 253° 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 wide and from 3,000 to 
5,000 feet high, occupies its central portion, on which rise 
peaks and domes of basalt and granite to a height of 
nearly 9,000 feet; and there are also numerous extinct 
voleanic 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. 
i gle ae 


Reunion 


_ 
7 Qa 
Sod Wie 

| 
re 
x, 


\.* 
Oe 
ra 
a2: 


= 
nt, 
Je 
a 
. 


ENCLAND 
to the same scale 


OF 


MADAGASCAR, 


The Shaded Fart shews the Elevated Grans- 
‘tic region; the Black dots,the Volcanic aistricts, 
|| while Dense Forests surround the Island 


CHAP. XIX THE MADAGASCAR GROUP 414 


The sea around Madagascar, when the shallow bank on 
which it stands is passed, is generally deep. This 100- 
fathom bank is only from one to three miles wide on the 
east side, but on the west it is much broader, and stretches 
out opposite Mozambique 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 one almost as narrow 
where the Comoro Islands seem to form stepping- 
stones to the continent of Africa. The 1,000-fathom 
line includes also 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- 
ing Madagascar from Bourbon and Mauritius. To the 
north-east of Mauritius are a series of extensive shoals 
forming four large banks less than 100 fathoms below the 
surface, while the 1,000-fathom line includes them all, 
with an area about half that of Madagascar itself. A little 
further 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. 425, are of 
great importance in explaining some anomalous features 
in the zoology of this great island. 

If the rocks of Secondary age which form a belt around 
the island are held to indicate that Madagascar was once 
of less 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 length, and varying in distance from the land from 


Ee 
a a a 


eT 
SS Ss SS SSS 


= ee Se SS ee 
eee 
SSeS Seas SSS 


CHAP. XIX THE MADAGASCAR GROUP 416 


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 Madagascar—Madagascar possesses 
an exceedingly rich and beautiful fauna and flora, rivalling 
in some groups most tropical countries of equal extent, 
and even when poor in species, of surpassing interest 
from the singularity, 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. 

Mammalia.—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 hyzenas; 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 
where we must look for their probable allies. 

First and most important are the lemurs, consisting 
of six genera and thirty-three species, thus comprising 
just half the entire mammalian population of the island. 
This group of lowly-organised and very ancient creatures 


417 ISLAND LIFE PART II 


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 b 
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 group distributed over all the 
great continents; and five genera of a peculiar family, 
Centetidee, 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, which are represented 
by a pecular 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 Potamocherus, 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 Viverride,” in Proc. Zool. Soc. 
1864, p. 507. : 

2 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.) 


CHAP. XIX THE MADAGASCAR GROUP 418 


tion, let us see what indications are afforded by the 
reptiles. The large and universally distributed family 
of Colubrine snakes is represented in Madagascar, not by 
African or Asiatic genera, but 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—Lycodontide and Viperide, 
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 
Iguanidz, a family which is exclusively American; while 
a genus of geckoes, inhabiting America and Australia, also 
occurs in Madagascar. 

elation of Madagascar to Africa.—These facts taken 
all together are certainly very extraordinary, since they 
show in a considerable number of cases as much affinity 
with America as with Africa; while the most striking 
and characteristic groups of animals now inhabiting Africa 
are entirely wanting in 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 HKuro-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 


419 ISLAND LIFE PART II 


in the latter portion of the Miocene or early in the 
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 would not 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 
Kurope, 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. 

Larly History of Afra and Madagascar—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 


1 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 Arctogea. Now 
there is every reason to believe, on other grounds, that both Hindostan 
south of the Ganges, and Africa south of the Sahara, were separated by a 
wide sea from Europe and North Asia during the Middle and Upper Eocene 
epochs. Hence it becomes highly probable that the well-known similari- 
ties, and no less remarkable differences, between the present faune of 
India and South Africa have arisen in some such fashion as the following : 
Some time during the Miocene epoch, the bottom of the nummulitic sea 
was upheaved and converted into dry land in the direction of a line 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 valleys of the 
Ganges and Arabia do now, many forms which made their way into Africa 
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 Geographical Distribution of 
Animals (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 his 
views here, 


CHAP. XIX THE MADAGASCAR GROUP 420 


Now these ancient African mammals are Lemurs, Insecti- 
vora, and small Carnivora, chiefly Viverride ; 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 Centetide, now confined to Mada- 
gascar and the West Indies, inhabited France in the Lower 
Miocene period, while the Viverride, or civets, which form 
so important a part of the fauna of Madagascar as well as 
of Africa, were abundant in Kurope 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 Explain Them.—It 


_ 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 Centetide 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 


42] ISLAND LIFE PART II 


a 


these cases we have ample proof of the former wide 
extension of the group. Extinct camels of numerous 
species abounded in North America in Miocene, Pliocene, 
and even Post-pliocene times, and one has also been found 
in 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 
Kocene period ; in the latter Hocene and the Miocene other 
forms occur both in Europe and North America. These 
seem to have become extinct in North America, while in 
Kurope 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 occupy 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 equally striking—show 
us with the greatest distinctness how nature has worked 
in bringing about the examples 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, where we rarely have any direct 
evidence of their past migrations through the discovery of 


CHAP. XIX THE MADAGASCAR GROUP 422 


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 migrations 
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 arid the permanence 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, aérial, and oceanic 
transport, and of whose distribution in early geological 
periods we generally know little or nothing. 

The Birds of Madagascar, as Indicating a Supposed 
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 peculiar ; 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, 

1 The total number of Madagascar birds is 238, of which 129 are 


493 ISLAND LIFE PART II 


belonging to known genera, we find fifteen which have 
undoubted African affinities, while five or six are as 
decidedly Oriental, the genera or nearest allied species 
being found in 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 Madagascar and the 
Adjacent Islands, lays great stress, as proving the former 
existence of “ Lemuria”; while he considers the absence 
of such peculiar African families as the plantain-eaters, 
glossy-starlings, ox-peckers, barbets, honey-guides, horn- 
bills, and bustards—besides a host of peculiar African 
genera—as sufficiently disproving the statement in my 
Geographical 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. Their 
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 have 


absolutely peculiar to the island, as are thirty-five of the genera. All the 
peculiar birds but two are land birds. These are the numbers given in M. 
Grandidier’s great work on Madagasear. | 


CHAP. XIX THE MADAGASCAR GROUP 424 


become partially or wholly submerged before they reached 
those countries; otherwise we should find in Madagascar 
many other animals besides Lemurs, Insectivora, and 
Viverride, 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 disappearance 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, 
species hardly distinguishable 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 difter- 
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 between 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 


425 ISLAND LIFE PART II 


sea—much deeper than that which divides Madagascar 
from Africa, and we have therefore no reason to imagine 
their former union. But they would nevertheless greatly 
facilitate the introduction of Indian birds into 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, 


eer 


PLT itt 


re 


il & 


| 
| 


iil 


——— 
——} 


nll 
il 
\ ! 


MAP OF THE INDIAN OCEAN. 


Showing the position of banks less than 1,000 fathoms deep between Africa and the 
Indian Peninsula. 


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 the 
case of the Azores and Bermuda how important a factor 


this is in determining the transport of birds across the 
ocean. 


CHAP. xix THE MADAGASCAR GROUP 426 


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 1s 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 the 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 Remarks on “ Lemwria.”—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 such a land in order to account for the entire 
series of phenomena connected with the Madagascar fauna, 
and especially with the distribution of the Lemuride.? I 

Eerne 10s, 1877, p. 334. 

* 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 bya continent, ‘‘and remained 
so connected with some short intervals from the Permian up to the end of 
the Miocene period,” and Mr. Woodward expressed his satisfaction with 
‘this further evidence derived from the fossil flora of 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- 


mentary evidence derived from such remote periods (even if there were no 
evidence on the other side) as indicating geographical changes. The notion 


FF 


427 ISLAND LIFE PART II 


think I have now shown, on the other hand, that it was 
essentially a provisional hypothesis, very useful in calling 
attention to a remarkable series of problems in geographical 
distribution, but not affording the true solution of those 
problems, any more than the hypothesis of an Atlantis 
solved the problems 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 Origin 
of Species, 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 what 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 twenty-five 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 reasons 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 similarity in the productions of widely separated continents at any 
past epoch is only to be explained by the existence of a direct land-con- 
nection, is entirely opposed to all that we know of the wide and varying 
distribution of a// types at different periods, as well as to the great powers 
of dispersal over moderate widths of ocean possessed by all animals except 
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 been shown above) with the 


actual facts of the distribution of animals. 
1 Geographical Distribution of Animals, Vol. 1., pp. 272—292. 


CHAP. XIX THE MADAGASCAR GROUP 4928 


The Mascarene Islands.—In the Geographical Distri- 
bution 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 
Kthiopian 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 
1 The term ‘‘ Mascarene ” is used here in an extended sense, to include 


all the islands near Madagascar which most nearly resemble it in their 
animal and vegetable productions. a s 
F Z 


499 ISLAND LIFE PART II 


which sixteen are peculiar to the islands, twenty-one are 
found also in Madagascar, and three found in Africa and 
not in Madagascar; while of the peculiar species, six 
belong 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 Archipelago—This interesting group 
consists of about thirty small islands situated 700 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 m a southern 
direction, All the larger islands are of granite, 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 
great 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 granitic 
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 ata 
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 


1 For the birds of the Comoro Islands see Proc. Zool. Soc., 1877, p. 295, 
and 1879, p. 673. 


Po) 
} 

; 

; 


CHAP. XIX THE MADAGASCAR GROUP 430 


—————— 


large islands, and may have supported a rich 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-aérial 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 im 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 Paleornis, 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 (Alectoreenas pulcherrimus) allied to those of Mada- 
gascar and Mauritius, but very distinct, are the most 
remarkable species characteristic of this group of islands. 

Reptiles and Amphibia of the Seychelles—The reptiles 
and amphibia are rather numerous and very interesting, 
indicating clearly that the islands can hardly be classed as 
oceanic. There are seven species of lizards, three being 
peculiar to the islands, while the others have rather a 
wide range. The first is a chameleon—defenceless slow- 


1 The following is a list of these peculiar birds. (See the Jdzs, for 1867, 
p. 359 ; and 1879, p. 97.) 


PASSERES. PSITTACI. 
Ellisia seychellensis. Coracopsts teste 84 
Copsychus seychellarum. P mn wardt. 
Hypsipetes crassirostris. CoLUMB. 
Tehitrea corvina. Alectorenas pulcherrimus 
Neciarinia dussumieri. Turtur rostratus. 
rors Seanes ACCIPITRES. 


Foudia seychellarum. Tinnunculus gracilis. 


431 ISLAND LIFE PART II 


—_ 


moving lizards, especially abundant in Madagascar, from 
which no less than eighteen species are now known, 
about the same number as on the continent of Africa. 
The Seychelles species (Chameleon tigris) also occurs at 
Zanzibar. The next are skinks (Scincidz), small ground- 
lizards with a wide distribution in the Eastern hemi- 
sphere. ‘Two species are however peculiar to the islands 
—Mabuwa seychellensis and. M. wrightit. The other 
peculiar species is one of the geckoes (Geckotide) named 
Ailuronyx seychellensis, and there are also three other 
geckoes, Phelsuma madagascarensis, Gehyra mutilata and 
Hemidactylus frenatus, 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 lable to be carried in ships from one country 
to another, and I am told by Dr. Giinther 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 seychellensis, is a peculiar species 
of the family Colubride, the rest of the genus being found 
in Madagascar and South America. The other, Boodon 
geometricus, one of the Lycodontide, or fanged ground- 
snakes, 1s also peculiar. So far, then, as the reptiles are 


CHAP. XIX THE MADAGASCAR GROUP 432 


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 Rana mascareniensis found also in 
Mauritius, Bourbon, West Africa, and Abyssinia, and 
probably all over tropical Africa; and Megalixalus 
seychellensis a peculiar tree-frog having allies in Mada- 
gascar and tropical Africa. It is found, Dr. Wright in- 
forms 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 con- 
fined each toa 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 Ceciliade. 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 jomted segments of a worm’s body, and when 
caught they exude a viscid slime. The young have 
external gills which are afterwards replaced by true lungs, 
and this peculiar metamorphosis shows that they belong to 
the amphibia rather than to the reptiles. The Cecilias 
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 two species of these 
singular animals. Hypogeophis rostratus is confined to the 
islands, while Herpelesqualostomaisfoundalsoin West Africa. 

Fresh-water Fishes——The only other vertebrates in the 
Seychelles are two fresh-water fishes abounding in the 


1 [In the last edition Hypogeophis rostratus was stated to be found also 
in South America on the authority of specimens in the Paris Museum 
collected by D’Orbigny. But Dr. Wright informs me that this locality 
for the species has not been confirmed and is probably erroneous. Hence 
the discussion upon it is now omitted. 


433-4 ISLAND LIFE PART II 


a 


streams and rivulets. One, Haplochilus playfairu, 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. Giinther, often inhabit 
both sea and fresh water, so that their migration from 
Madagascar to the Seychelles and subsequent modification, 
offers no difficulty. The other species is Sundulus 
orthonotus, found also on the east coast of Africa; and as 
both belong to the same family—Cyprinodontidee—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 mollusca, but 
they do not furnish any facts of special interest. About 
forty species are known, and Mr. Geoffrey Nevill, who has 
studied them, thinks their meagre number is chiefly owing 
to the destruction of so much of the forests which once 
covered the islands. Seven of the species—and among 
them one of the most conspicuous, Achatina fulica—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 are mentioned as 
being especially Indian, while only two are found in 
Madagascar but not in India.!. Only one-fourth of the 
species appear to be peculiar to the islands, according to the 
latest enumeration by Von Martens and Weigmann in 1898. 
Mauritius, Bourbon 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 


1 «* Additional Notes on the Land-shells of the Seychelles Islands.” By 
Geoffrey Nevill, C.M.Z.S. Proc. Zool. Soc. 1869, p. 61. 


CHAP XIX THE MADAGASCAR GROUP 435 


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- 
gascar, and this view is strongly supported by the character 
of their indigenous fauna. Of this, however, we have not 
a very complete or accurate knowledge, for though both 
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 


1 In Maillard’s Notes sur [Isle de Réunion, a considerable number of 
mammalia are given as ‘‘ wild,” such as Lemur mongoz and Centetes setosus, 
both Madagascar species, with such 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 
and certainly imported, as are most probably the frogs. Legouat, who 
resided some years in the island nearly two centuries ago, and who was 
a closer observer of nature, mentions numerous birds, large bats, land- 
tortoises, and lizards, but no other reptiles or venomous animals except 
scorpions. We may be pretty sure, therefore, that the land-mammalia, 
snakes, and frogs, now found wild, have all been introduced. Of lizards, 
on the other hand, there are several species, some peculiar to the island, 
others common to Africa and the other Mascarene Islands. The following 
list by Prof. Dumeril is given in Maillard’s work :— 


Platydact, lus cepedianus. Hemidactylus frenatus. 
9s ocellatus. Gongy lus bojerit. 
Hemidactylus peronii. Ablepharus peronii. 
os mutilatus. 


Four species of chameleon are now recorded from Bourbon and one from 
Mauritius (J. Reay Greene, M.D., in Pop. Science Rev. April, 1880), but 
as they were not mentioned by the old writers, itis pretty certain that these 
creatures are recent introductions, and this is the more probable as they 
are favourite domestic pets. 

Darwin informed me that in a work entitled Voyage a VIsle de France, 
par un Officier dw Roi, published in 1770, it is stated that a fresh-water fish 
had been introduced from Batavia and had multiplied. The writer also 
says (p. 170): ‘* On a essayé, mais sans succes, dy transporter des grenourtles 
qui mangent les eufs que les moustigues deposent sur les\eaux stagnantes.” 
It thus appears that there were then no frogs-on the island. 


436 ISLAND LIFE PART II 


for the poverty of its fauna and flora. It stands ona 100- 
fathom bank of considerable extent, but beyond this the 
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, be- 
longing to the Campephagidee 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 grou 
of large ground-birds, quite incapable of flight, and 
altogether unlike anything found elsewhere 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 resided in Rodriguez in 1692. 
These birds constitute a distinct family, Didide, allied to 
the pigeons but very isolated. They were 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 whatever, 
is itself almost demonstrative that Mauritius, Bourbon, and 
Rodriguez are very ancient but truly oceanic islands. 
From what 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 


ae 


—— 


CHAP. XIX THE MADAGASCAR GROUP 437 


oe ee 


and multiply unchecked by the.attacks of any more power- 
ful animals, we can well understand that the wings, being 
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 might be 
absolutely prejudicial to the birds in their new home. 
Those that flew up into trees to roost, or tried to cross 
over the 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 the more bulky and _ short-winged 
individuals, who took tosleeping on the ground in the forest, 
would be preserved fromsuch dangers, and perhaps also from 
the attacks of birds of prey which may always have visited 
theislands. 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 complete 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 


ee es ee 


1 That the dodo is really a degradation from a higher type, and not a 
direct development from some lower form of wingless bird, is shown by its 
possessing a keeled sternum, though the keel is exceedingly reduced, being 
only three-quarters of an inch deep in a length of seven inches, The most 
terrestrial pigeon—the Didunculus of the Samoan Islands, has a far deeper 
and better developed keel, showing that in the case of the dodo the degrada- 
tion has been extreme. We have also analogous examples in other extinct 
birds of the same group of islands, such as the flightless Rails—Aphan- 
1 apteryx of Mauritius and Erythromachus of Rodriguez, as well as the 

large parrot—Lophopsittacus of Mauritius, and the Night Heron, 

Nyeticorax megacephala 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 peculiar dove of the Seychelles, Turtwr rostratus, which, as 
- Mr. Edward Newton has shown, has much shorter wings than its close 
ally, 7. picturatus, of Madagascar. For a full and interesting account of 
these and other recently extinct birds see Professor Newton’s article on 
“Fossil Birds” in the Encyclopedia Britannica, ninth edition, vol. ii1., 
p. 732; and that on ‘‘ The Extinct Birds of Rodriguez,” by Dr. A. Gunther 
and Mr. E. Newton, in the Royal Society’s volume on the Transit of Venus 


Expedition. 


ee eS See se el 


438 ISLAND LIFE PART II 


it at the same period ; and we may therefore be sure that 
these islands have never formed part of a continent during 
any portion of the time when the dodos inhabited them. 

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 points 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 
Aipyornis, 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 peculiar species ; but no snakes, and no frogs or 
toads but such as have been introduced.2 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 alsoin any other part of the world, being 
altogether confined to this minute islet! It belongs to 


1 See Jbis, 1877, p. 334. 

2 A common Indian and Malayan toad (Bufo melanostictus) has been 
introduced into Mauritius and also some European toads, as I am informed 
by Dr. Gunther. 


i te Me, * el 


Se 


OHAP. XIX THE MADAGASCAR GROUP 439 


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 
bayert, recorded also from Mauritius and Bourbon, though 
it appears to be rare in both islands; but a gecko, Phelsuma 
guenthert, is restricted to the island. As Round Island is 
connected with Mauritius by a bank under a hundred 
fathoms below the surface, it has probably been once 
joined to it, and when first separated would have been 
both much larger and much nearer the main island, 
circumstances which would greatly facilitate the 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 Mascarene 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 be 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, but of the two 
affinities the former greatly preponderates. There 
are also, as in the animal world, some decided South 
American relations, while other groups point to Australia, 
or are altogether isolated. 


440 ISLAND LIFE PART II 


About 3,740 flowering plants were known from Mada- 
gascar in 1889, with 360 ferns and fern-allies. The most 
abundant natural orders are the following: 


Species 
DOPAR IU SEE 2, Sic nics einai os ha onic ss Wom een 346 
A Re AB a pore ot Mn a hone aR Td) a So, > 318 
Com pOnntat Gk. hie. URC aaa PS eee 281.2 
PpIvorietes! ) x codsbivnsel raga Beads See lad 228 
CHEM Os Se ise dso cuneate hae ae 170 
OP MePaCere lo ers Hieeei ac eadeenee eat ee eee 160 
Wea BimGeas 052 1S, 580i cate ne ae Rreeeye ry. 147 
A ea OO8 oano5 ie Fid.cis wick caateciaal doa aban ee ee 131 
RRPAMEAIN CTE hoa yt acai tare cc Cv As ods daisy Me aR ate OE . tao 


The flora contains representatives of 144 natural orders and 
970 genera, one of the former and 148 of the latter being 
peculiar to the island. The peculiar order, Chelnacee, 
comprises seven genera and twenty-four species; while ~ 
Rubiacere and Composite have the largest number of 
peculiar genera, followed by Leguminose and Melastomacee. 
Mr. Hemsley now estimates the flowering plants at about 
4.500, of which nearly three-fourths are endemic. 
Beautiful flowers are not conspicuous in the flora of 
Madagascar, though it contains several magnificent 
flowering plants. A shrub with the dreadful name 
Harpagophytum Grandidiert has bunches of gorgeous 
red flowers; Tristellateia madagascariensis is a climbing 
plant with spikes of rich yellow flowers; while Poinciana 
regia, a tall tree, Rhodolena altwola and Astrapea 
Walitchii, shrubs, are among the most magnificent 
flowering plants in the world. Disa Buchenaviana, Com- 
melina madagascarica, and Tachiadenus platypterus are 
fine blue-flowered plants, while the superb orchid Angre- 
cum  sesquipedale, Vinca rosea, Kuphorbia  splendens, 
and Stephanotis floribunda, have been long cultivated 
in our hot-houses. There are also many handsome 
Combretacee, Rubiaceze, and Leguminose ; 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 is allied, generally, to that of 
tropical Africa, while the plants of the highlands are 
equally allied to those of South Africa and the mountains 


CHAP. XIX THE MADAGASCAR GROUP 441 


of Central Africa. A few Asiatic types are present which 
do not occur in Africa; and even the curious American 
affinities of some of the animals are reproduced in the 
vegetable kingdom. These last are so interesting that 
they deserve to be enumerated. An American genus of 
Kuphorbiaceze, Omphalea, has one species in Madagascar, 
and Pedilanthus, another genus of the same natural order, 
has a similar distribution. Myrosma, an American genus 
of Scitamineze has one Madagascar species; while the 
celebrated “ travellers’ tree,’ Ravenala madagascariensis, 
belonging to the order Musacee, has its nearest ally in a 
plant inhabiting N. Brazil and Guiana. Echinolena, a 
genus of grasses, 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 Mauritius and the Seychelles, 
including also Rodriguez. The total number of species 
in this flora is 1,058, more than half of which (536) 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 curious Asiatic preponderance. With the genera, how- 


ever, the proportions are different, for 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 
immigration has been from the side of Africa, while a 
more recent influx, shown by identity of species, has come 
from the side of Asia. This is no doubt due to those 
facilities for immigration which have been already dis- 
cussed in the early part of this chapter in reference to 
the supposed continuous land connection between Mada- 
gascar and southern India, and which would certainly be 
much more effective in the case of plants. 


1 This brief account of the Madagascar 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 Linnean Society, Vol. XXV. (1889), p. 246; where much 
information is given on the distribution of the flora within the island. 


442 ISLAND LIFE PART It | 

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 species 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 complete extinction through 
the attacks of enemies or through changes of climate or 
of physical geography; hence we find comparatively few 
cases in which groups of Madagascar plants have their 
only allies in such distant regions as America and Aus- 
tralia, while 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 Sterculiaceze, has four species in Mauritius, one in 
Madagascar, and one in the remote island of St. Helena. 
Mathurina, a genus of Turneraceze, 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 Composite, consists 
of two species, one inhabiting the Mascarene islands, the 
other Peru. Labourdonasia, a genus of Sapotacez, 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 Lauracez, has six species m 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 aay 


and in Madagascar. Milla, a large genus of Liliacex, ig 
exclusively American, except one species found in Mauri- 
tius and Bourbon. Agauria, a genus of LKricaces, 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. 
heterophylla), can hardly be separated specifically from 
Acacia koa of the Sandwich Islands. The genus Pandanus, 
or screw-pine, has sixteen species in the three islands— 
Mauritius, Rodriguez, and the Seychelles—all bein 

peculiar, and none ranging beyond a single island. Of 
palms there are fifteen species belonging to ten genera, 
and all these genera are pecular 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 than physical and geological evidence 
-warrants.! 


1 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 Mauritius and the Seychelles, as they are nowhere separately tabulated 
in that work. 


Aphloia (Bixacez) .....................1 sp., a Shrub, Maur., Rod., Sey., also Madagascar. 
Medusagyne (Ternstromiacea ) ...1 sp., a shrub, Seychelles. 


Astiria (Sterculiacese) ......... .... 
Quivisia (Meliacez) ............ 


Cossignya (Sapindacee) ..... 
Hornea ; Be tek netads 


Stadtmannia Ze 


Doratoxylon __,, peecastennt 
Gagnebina (Leguminosz)........... 
Roussea (Saxifragacez).............. 
Tetrataxis (Lythracez).............. 


Psiloxylon . 


Mathurina (Turneraces) es 
Poetidia (Myrtacez) .............000 
Boeniis (TRUDIACET) ...........2 002 0e008 


Fernelia (Rubiaces) .............000+ 


Pyrostria a 


Seyphochlamys (Rubiacez) 
Myonima 


Cylindrocline (Composite) aewaiee 


Monarrhenus 


9 


.l sp., a Shrub, Mauritius. 
...3Sp., shrubs, Mauritius (2 sp.), Rodriguez (1 sp.), 


also Bourbon. 


......L Sp., @ shrub, Mauritius, also Bourbon. 

..l sp., a shrub, Mauritius. 

....1 Sp., a Shrub, Mauritius. 

...1 Sp., a Shrub, Mauritius and Bourbon. 

.l sp., a shrub, Mauritius, also Madagascar, 

.l sp., a climbing shrub, Mauritius and Bourbon. 
.l sp., a shrub, Mauritius. 

...1 sp., a shrub, Mauritius and Bourbon. 

...1 sp., a shrub, Rodriguez. 

.l sp., a tree, Mauritius. 

.4sp., climbing shrubs, Maur. (1 sp.), Rodr. (1 sp.), 


also Bourbon and Madagascar. 


.1 sp., a shrub, Mauritius and Rodriguez. 
......6 8p., shrubs, Mauritius (3 sp.), also Bourbon and 


Madagascar. 


odd 1 sp., a shrub, Rodriguez. 

aoaes 3 sp., shrubs, Mauritius, also Bourbon. 

.l sp., a shrub, Mauritius. 

..2 sp., shrubs, Mauritius, also Bourbon and Mada- 


gascar. 


GG 


444 ISLAND LIFE PART II 

Fragmentary Character of the Mascarene Flora— 
Although the peculiar character and affinities of the 
vegetation of these islands 1s 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 imevit- 
ably have beenexterminated. The result is, thatnearly three 
hundred species of foreign plants have run wildin Mauritius, 
and have in their turn helped to extinguish the native 


Faujasia (Composit) .............3 Sp., shrubs, Mauritius, also Bourbon and Mada- 
gascar. 

Heterochenia (Campanulacez)...... 1 sp., a shrub, Mauritius, also Bourbon. 

Tanulepis (Asclepiadacez)............1 sp., a climber, Rodriguez. 


Decanema ..1 sp., a climber, Mauritius, also Madagascar. 


3 2 eee eeesee 
Nicodemia (Loganiacez).............. 


Bryodes (Scrophulariacez)........... 


Radamezea 


rs A 9° eevee eee 
Colea (Bignoniacee) .........000..6 


Obetia (Urticacem) 0. ..v.ccceesaoses 


Bosquiea (Morece)..........0.eceseeee 
Monimia (Monimiacez) .........6. 


.2sp., shrubs, Mauritius (1 sp.), also Comoro Islands 
and Madagascar. 
.l sp., herb, Mauritius. 


...2 sp., herb, Seychelles (1 sp.), and Madagascar. 
..10 sp., Mauritius (1 sp.), Seychelles (1 sp.), also 


Bourbon and Madagascar. (Shrubs, trees, or 
climbers.) 


..2 Sp., shrubs, Mauritius, Seychelles, and Mada- 


gascar. 


....3 Sp., trees, Seychelles (1 sp.), also Madagascar. 
....3 Sp., trees, Mauritius (2 sp.), also Bourbon. 


Cynorchis (Orchidez) ..................3 Sp., herb, ter., Mauritius. 

Amphorchis 3 seseeeeeeeeeesseeel SP., herb, ter., Mauritius, also Bourbon. 

Arnottia we ...---2 Sp., herb, ter., Mauritius, also Bourbon. 
Aplostellis $3 sesoeeel SP., herb, ter., Mauritius. 

Cryptopus ” 1 sp., herb, Epiphyte, Mauritius, also Bourbon and 


Lomatophyllum (Liliacez) .......... 


Madagascar. 


..3 Sp., Shrubs (succulent), Mauritius, also Bourbon. 


Lodoicea (Palmz) ............+.1 Sp., tree, Seychelles. 

Latania a wusssscesesseeed SP., trees, Mauritius (2 sp.), Rodriguez, also 
Bourbon. 

Hyophorbe os ....3 sp., trees, Mauritius (2 sp.), Rodriguez, also 
Bourbon. 

Dictyosperma ae Lissueel Sp., tree, Mauritius, Rodriguez, also Bourbon, 

Acanthophenix __,, sssseee2 Sp., trees, Mauritius, also Bourbon. 

Deckenia aS ..seel Sp., tree, Seychelles. 

Nephrosperma . ....1 sp., tree, Seychelles. 


Roscheria 


Stevensonia om 
Ochropteris (Filices) 


7 OLELIIL sp., tree, Seychelles. 
Verschaffeltia os eavbxuaniaaea 


-lsp., tree, Seychelles. 


wees SP., tree, Seyehelles. 
....1 sp., herb, Mauritius, also Bourbon and Madagascar. 


Among the curious features in this list are the great number of endemic 
shrubs in Mauritius, and the remarkable assemblage of five endemic genera 


of palms in the Seychelles Islands. 


We may also notice that one palm 


(Latania loddigesii) is confined to Round Island and two other adjacent 
islets, offering a singular analogy to the peculiar snake also found there. 


EES ne ee —— 


‘OHAP, XIX THE MADAGASCAR GROUP 445 


species. In the Seychelles, too, the indigenous flora has 
been almost entirely destroyed in most of the islands, 
although the peculiar palms, from their longevity and 
comparative hardiness, have survived. Mr. Geoffrey Nevill 
tells us, that at Mahé, 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. Pine-apples, cmnamon, 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 dry and arid; and the same effect is 
largely seen both in Mauritius and Bourbon, where, 
originally, dense forest covered the entire surface, and 
perennial moisture, with its ever-accompanying luxuriance 
of vegetation, prevailed. 

Flora of Madagascar Allied to that of South Africa.—In 
my Geographical Distribution of Animals I 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 Composite, 
He says: “The connections of the Mascarene endemic 
Composite, especially those of Madagascar itself, are 
eminently with the southern and sub-tropical African 
races; the more tropical races, Plucheinee, &c., may be 
rather more of an Asiatic type.” He further says that the 
Composite flora is almost as strictly endemic as that of 
the Sandwich Islands, and that it is much diversified, with 
evidences of great antiquity, while it shows insular char- 
acteristics in the 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 orchideex. The following figures are taken from 

G G2 


446 ISLAND LIFE PART II 
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 :— 


Mauritius, cc. Bourbon. 
Le nt ea oo eee 168 Horm 5.2695: <-heocee 240 
SRCDINES 3. isis te sacs 79 Orehides® vo) nsec 120 
GRAINGER 055055205 8 69 Graminied .). 3.2.48 60 
Oyperaceés.....3 0h. 62 Compostt® | s.0:0dsc.. 60 
PPUDAACERS 6 hc. aie'v enn 57 Legumingse ; 252. ..54% 36 
Kuphorbiacee ......... 45 Teabiaves 205... 385 064 24 
Composite  .5..4.00 43 Cyperacess:.. 3.12 ae 
Leguminose ............ 41 Euphorbiacee .,... ... 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 
Rodriguez 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 epiphytic 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 plants. 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 
which are not too far removed from other lands or conti- 
nents from which their seeds might be conveyed. 

Concluding Remarks on Madagascar and the Mascarene 
Islands.—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 


CHAP. XIx THE MADAGASCAR 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 supply 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 genera, indicating 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 applies 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 Palzeozoic—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. Ata 
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 
island ; and thus, when the large mammalia from the 
northern continent overran Africa, they were prevented 
from reaching Madagascar, which thenceforth was enabled 
to develop its singular forms of low-type mammalia, its 
gigantic ostrich-like ipyornis, 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 1s 
to accept the results of geological and_ paleontological 
science, and the ascertained facts as to the powers of 
dispersal of the various animal groups; to take full 
account of the laws of evolution as affecting distribution, 


CHAP. XIX THE MADAGASCAR GROUP 449 


and of the various ocean depths as implying recent or 
remote union of islands with their adjacent continents ; 
and the result is, that wherever we possess a sufficient 
knowledge of these various kinds 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 think, 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 especially 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 Madagascar fauna and flora 
are now so often to be found in South America or 
Australia—countries in which low forms of mammalia and 
birds still largely prevail;—it being on account 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 fauna 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 explained. 


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 Derivation 
of the Mammals 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 


CHAP. xx CELEBES 451 


volcanoes; it is connected with the British Islands and 
with Greenland by seas less than 500 fathoms deep; and 
it possesses a few mammalia, one of which is peculiar, and 
at least three peculiar species of birds. It was therefore 
almost certainly united with Greenland, and probably with 
Kurope by way of Britain, in the early part of the Tertiary 
period, and thus afforded one of the routes by which that 
intermigration of American and Kuropean animals and 
plants was effected which we 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 poor, and offer so few peculiarities, 
that it 1s 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 with either of 
the great continents. Although I have pretty fully dis- 
cussed its zoological peculiarities and past history in my 
Geographical Distribution 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 position for determining its true zoo-geographical 
relations. 

Physical Featwres of Celebes—This large and still com- 
paratively unexplored island is interesting to the geo- 
grapher 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 
very little known. The extremity of the northern pen- 
insula is volcanic; while in the southern peninsula there 
are crystalline limestones of secondary age, in some places 
overlying basalt. Gold is found in the northern peninsula 
and in the central mass, as well as iron, tin, and copper in 
small quantities. Granite and gneiss occur in all the 


452 ISLAND LIFE 


PART II 


chief mountain ranges, which, no doubt, consist largely of 
ancient stratified rocks. 


BORNEO 
EQUATOR 


wi 
au 


atin 


| 


Nips 
vt 


ba 


MAP OF CELEBES AND THE SURROUNDING ISLANDS. 


The depth of sea is shown by three tints: the lightest indicating less than 100 
fathoms, the medium tint less than 1,000 fathoms, and the dark tint more tha 
1,000 fathoms. The figures show depths in fathoms. ‘ 


It is not yet known whether Celebes is completely 
separated from the surrounding islands by a deep sea, but 


ee 


y 


CHAP. XX _CELEBES 453 


_ the facts at our command render it probable that it is so. 
The northern and eastern portions of the Celebes Sea have 
been ascertained to be from 2,000 to 2,600 fathoms deep, 
and such depths may extend over a considerable portion of 
it, or even be much exceeded in the centre. In the 
Molucca passage a single sounding on the Gilolo side gave 
1,200 fathoms, and a large part of the Molucca and Banda 
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 Borneo 
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 much 
shallowed by the deposits from the great Bornean rivers as 
well as by those of Celebes itself. Southward again, the 
_ 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 con- 
cluding that Celebes is entirely surrounded by a deep sea, 
which has, however, become partially filled up by river 
deposits, by volcanic upheaval, or by coral reefs. Such 
shallows, where they exist, may therefore indicate antiquity 
and isolation, instead of being proofs of a former union 
with any of the surrounding islands. 

Zoological 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 divide 
broadly into two groups, those on the west belonging to 
the Oriental region of our zoological geography, and those 
on the east belonging to the Australian region. Of the 
first group Borneo is a typical representative ; and from its 
proximity and the extent of its opposing coasts it is the 
island which we should expect to show most resemblance to 
Celebes. We have already seen that the fauna of Borneo 
is the same general character as that of Southern Asia, 
and that it is excessively rich in all the Malayan types of 


454 ISLAND LIFE PART II 


mammalia and birds. Java and Bali closely resemble 
Borneo in general character, though somewhat less rich 
and with several peculiar forms; while 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 whole, may be 
described as having a fauna almost identical with 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 ; while 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 
find here four families of Marsupials, all totally unknown 
in the western islands. Even birds, though usually more 
widely spread, show a corresponding difference, about 
eleven Malayan families being quite unknown east of 
Celebes, where six new families make their appearance 
which are equally unknown to the westward. 

We have here a radical difference between two sets of 
islands not very far removed from each other, the one set 
belonging zoologically to Asia, the other to Australia. 
The Asiatic or Malayan group is found to be bounded 
strictly by the eastward limits of the great bank (for the 
most part less than fifty fathoms below the surface) which 


1 Families of Malayan Birds not Families of Australasian Birds 


found in islands East of not found in islands West of 
Celebes. Celebes. 
Troglodytide. Paradiseide. 
Sittide. Meliphagide, 
Paride. Cacatuide. 
Liotrichide. Platycercide. 
Phylornithide. Trichoglosside 
Eurylemide. Nestoride. 
Picide. 
Indicatoride. 
Megalemide. 
Trogonide. 


Phasianide. 


CHAP. XX CELEBES 455 
stretches out from the Siamese and Malayan peninsulas 
as far as Java, Sumatra, Borneo, and the Philippines. To 
the east another bank unites New Guinea and the Papuan 
Islands as far as Aru, Mysol,and Waigiou, with Australia ; 
while the Moluccas and Timor groups are surrounded by 
much deeper water, which forms, in the Banda and 
Celebes Seas and perhaps in other parts of this area, great 
basins of enormous depth (2,000 to 3,000 fathoms, or even 
more) enclosed by tracts under a thousand fathoms, which 
separate the basins from each other and from the adjacent 
Pacific and Indian oceans (see map). This peculiar 
formation of the sea-bottom probably indicates that this 
area has been the seat of great local upheavals and 
subsidences ; and it 1s quite in accordance with this view 
that we find the Moluccas, while closely agreeing with 
New Guinea in their forms of life, to be 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 a 
somewhat parallel relation to Borneo, being equally defi- 
cient in many of the higher mammals; 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 con- 
sequent 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 disturbance, probably involving extensive sub- 
mersions of the land, resulting in a more or less frag- 
mentary vertebrate fauna. 

Zoology of Celebes—The zoology of Celebes differs so 
remarkably from that of both the great divisions of the 
Archipelago above indicated, that 1t 1s very difficult to 
decide in which to place it. It is now known to possess forty- 
four species of terrestrial mammalia, besides thirty-nine 
bats, so that it is at once distinguished from Borneo and 
Java by its extreme poverty in this class. The following 
list has been kindly furnished me by Dr. A. B. Meyer, 


455a ISLAND LIFE PART II 


but local varieties and species probably introduced by 
man have been omitted. 
LIST OF THE TERRESTRIAL MAMMALIA OF CELEBES. 
(Those in italics are peculiar.) 
Macacus maurus. 


' 
E »»  eynomolgus. Perhaps introduced. 
3 & | Cynopithecus niger. : 
oO F | Tarsius Ffuscus. Allied to T. spectrum of Borneo. 
i. 3 f Crocidura fuliginosa. Tenasserim. 
Ses 2 5 
2 6 \Pachyura murina. China and Malaya. 
a2 © (Viverra tangalunga. Borneo, &c. 
"= $4 Paradoxurus hermaphroditus. Borneo, &c, 
32 me musschenbroeki. 
= Sciurus leucomus. 
5»,  tonkeanus. 
>»  ‘weberr. 
»  notatus. Borneo. 
» Ssarasinorwi., 
»,  prevosti. Borneo. 
»,  murinus. Sumatra. 
5 rubriventer. 
Mus neglectus. Borneo. 
»» mulleri. Borneo. 
«=| » ephippium. Borneo. 
c= » musschenbrocki. 
3 », callitrichus. 
S| 4, hellwaldi. 
a », xanthurus. 
5) gf pets. 
55 . CeCcari. 
»» minahassa. 
», celestis, 
,, giganteus. ‘‘The bandicoot.” India. (? introduced.) 
Gymnomys celebensis. 
Leuomys meyert. Allied to New Guinea and Philippine groups. 
Craurothrix leucura. 
Acanthion javanicum ? Malay Islands. 
Sus celebensis. 
4g | Babirusa alfurus. The babirusa or ‘‘ Hog-deer.” _ 
bo (Cervus moluccensis. Moluccas, Allied to C. hippelaphus of 
— Borneo. 
Anoa depressicornis. 
“ide Manis javanica? Borneo and Java. 
aim 8 , : Ursinus. . 
= B'S nh Sy tei: cele ons | Marsupials of Papuan type. 


We have here forty well-marked species of truly 
terrestrial mammals, of which twenty-three are peculiar. 
This gives a proportion of nearly two-thirds, which 1s 


ee So ee 


CHAP. XX CELEBES 455Db 


considerably more than in Borneo, but not quite so 
much as in the more isolated Philippines. The non- 
peculiar species are all or nearly all found also in the 
Sunda Islands or the Asiatic continent; but among 
the peculiar forms there are two marsupials and several 
of the mice which must have been derived from the 
Australian region. The majority of the peculiar species 
are also either of Malayan or continental derivation, but 
several of them are so distinct from any known animals 
as to indicate a very remote origin. 

Among the interesting features of this list we may 
note the following: (1) Its extreme poverty; for although 
all the orders are represented, the few Insectivora and 
Carnivora consist of small species which are all but one 
natives of the adjacent countries, some of which may 
have been introduced by man. (2) It is only among 
the arboreal rodents that there is a fuller repre- 
sentation of forms, and among these a large proportion 
are peculiar species, indicating their introduction by 
natural agencies and a considerable antiquity. (3) The 
presence of peculiar species of monkeys and squirrels. 
which here reach their farthest extension in the eastern 
tropics. (4) The presence also of two peculiar species of 
Marsupials of Papuan type which here reach their 
farthest western extension. 

But besides these indications of isolation and antiquity 
Celebes possesses three remarkable animals, all of large 
size and not closely allied to anything found in the Malay 
Islands or even in Asia. These are a black and almost 
tailless baboon-like ape (Cynopitheus niger); an ante- 
lopean buffalo (Anoa depressicornis), and the strange 
babirusa (Babirus alfurus). 

Not only have these three animals no close allies else- 
where, but they are all peculiar genera, 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. Thé ape is apparently 
somewhat intermediate 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 


456 ISLAND LIFE PART II 
its flat projecting muzzle, large superciliary crests, and 
maxillary ridges. The anoa, though anatomically allied 
to the buffaloes, externally more resembles the bovine 
antelopes of Africa; while the babirusa is altogether 
unlike any other living member of the swine family, the 
canines of the upper jaws growing directly upwards like 
horns, forming a spiral curve over the eyes, instead of 
downwards, as in all other mammalia. An approach to 
this peculiarity 1s made by the African wart-hogs, in 
which the upper tusk grows out laterally and then curves 
up; but these animals are not otherwise closely allied to 
the babirusa. 

Probable Derivation of the Mammals of Celebes.—It is 
clear that we have here a group of extremely peculiar, and, 
in all probability, very ancient forms, which have been 
preserved to us by isolation in Celebes, just as the mono- 
tremes and marsupials have been preserved in Australia, 
and so many of the lemurs and Insectivora in Madagascar. 
And this compels us to look upon the existing island as a 
fragment of some ancient land, once perhaps forming part 
of the great northern continent, but separated from it far 
earlier than Borneo, Sumatra, and Java. The exceeding 
scantiness of the mammalian fauna, however, remains to 
be accounted for. Wemay 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 80 connected by intervening islands 
separated 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 


ee) 


CHAP. Xx CELEBES 457 


as might readily pass over narrow straits from island to 
island ; and we are thus better enabled to understand the 
very small numbers of the arboreal monkeys, of the Insec- 
tivora, and of the numerous and varied Carnivora and 
Rodents, all so abundant in Borneo, but which, except the 
squirrels and mice, are so scantily represented in Celebes. 

The question at issue can only be finally determined by 
geological investigations. If Celebes has once formed part 
of Asia, and participated in its rich mammalian fauna, 
which has been since destroyed by submergence, then some 
remains of this fauna must certainly be preserved in caves 
or in 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 at 
any time 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 1s afforded 
by the birds and any other groups of which we have 
sufficient information. Since the last edition of this work 
was issued much has been done in the further exploration 
of the island and its outlying islets by naturalists and 
collectors, and the results, as regards the birds, have been 
collected in the fine work on the Birds of Celebes, published 
by Dr. Meyer and Mr. Wigglesworth in 1898. The list of 
species at the end of this chapter, and most of the facts as 
to distribution, are derived from this volume. 

Besides the main island, with its northern, southern, 
and two eastern peninsulas, there are a number of islands 
and islets around Celebes which evidently belong to it, and 
which, besidesagreeing generally withitin their productions, 
often possess peculiar species of their own. These are the 
Sanguir Islands on the extreme north, the Sula and Peling 
Islands on the north-east, the Bouton group on the south- 
east, and Salayer on the south, besides the Togian Islands 
in the Gulf of Tomini. All these islands have now been 
more or less explored by bird-collectors, and lists are 
given in the above-named work of the species which have 

H H 


458 ISLAND LIFE PART II 
been found in each of them. In order not to exaggerate the 
peculiarities of the Celebesian fauna, I shall here only take 
notice of what Messrs. Meyer and Wigglesworth consider to 
be distinct species, omitting the numerous sub-species or 
varieties which they have given as peculiar in their lists. 

In discussing the chief features of Celebes as a zoo- 
geographical area or province, we must of course include the 
various islets which surround it, and which at one time or 
another have probably formed parts of it. Butit is also 
interesting to consider the main island and its dependent 
islets separately, since each has peculiar features and 
relations of much interest from the evolutionary standpoint. 

The land-birds of the whole Celebesian area now known 
amount to 289 species, and no less than 170 of these are 
peculiar to it, giving a proportion of three-fifths. This is 
a much larger proportion than in Borneo, but considerably 
less than in the Philippines, where nearly three-fourths are 
peculiar. But if we consider how closely Celebes is sur- 
rounded by Borneo, Java and the Moluccas, its amount of 
speciality is even more remarkable than in the last: named 
islands, which are not only very much more extensive but 
are also much more isolated. 

Taking the main island of Celebes by itself, we find that 
it has 207 species, of which 114 are peculiar, a proportion 
somewhat smaller than that of the whole group, due to 
the fact that of the species in the Celebesian islets which 
are not found in the main island, a considerably larger 
proportion (more than two-thirds) are peculiar. When we 
consider the birds of the Celebesian group with regard 
to their affinities and probable origin, we find a very 
curious and suggestive difference between Cclebes proper 
and its surrounding islets. Omitting all the species which 
have a very wide distribution and may have entered 
the island from either the west or the east, and omitting 
also those whose only near allies are in the Philippines, 
since most of these have probably entered those islands 
from Celebes, we find that about 20 of the peculiar species 
of the main island have been derived from the Australian 
region, while about 30 must have entered the island from 
the Oriental region. And the species which are identical 


= mC 


_ . o - 
= 4 


CHAP. Xx ~ CELEBES 459 


with those of other lands show similar proportions, 18 
belonging to the Moluccas, New Guinea or Australia, while 
48 are clearly derived from Borneo or other Malayan lands. 
Combining the two, we find the following result. 


_ Derwation of the Land-birds of Celebes proper. 


Oriental Region. | Australian Region. 
Peculiar species . . 29 Peculiar species . . 20 
Non-peculiar species 48 Non-peculiar species 18 

Lo) deere os Total ... 38 


Dr. Meyer seems to consider that this great preponder- 
ance of Malayan or Oriental affinity must settle the question 
of the position of the island in the Oriental region. But 
this is not quite so clear as at first sight it appears to be. 
On the one side we have a very rich island, Borneo, on the 
other the comparatively poor, small, and more remote 
Moluccas, with Australia and New Guinea still farther 


removed ; and it seems probable that the proportion of 


the whole bird fauna of Borneo which has reached Celebes 
is less than the corresponding proportion of Moluccan birds. 

We cannot tabulate the birds of the Celebesian islets 
in quite the same way, because almost all their peculiar 
species are modifications of those in the main island. 
But we find there two Australian or Papuan genera, Kos 
and Aprosmictus, which are unknown in Celebes itself, 
and there are also no less than twenty species of 
Moluccan, Papuan, or Australian birds which do not 
inhabit Celebes, while there are only three species of 


Oriental birds which are not found in the parent island. 


But, further, we find that no less than twenty-eight 
species found in the islets and not in Celebes belong to 
genera which either wholly belong to the Australian 
region or are highly characteristic of it. These are 
Megapodius (3 sp.), Carpophaga (4 sp.), Ptilopus (4 sp.), 
Trichoglossus (2 sp.), Eos (1 sp.), Aprosmictus (1 sp.), 


Tanygnathus (2 sp.), Loriculus (3 sp.), Monarcha (2 sp.), 


and Pachycephala (6 sp.), and these give a distinctive 
character to the ornithology of the Celebesian islets. 
| H H 2 


459a ISLAND LIFE PART II 


The difference here indicated is what might be expected 
on the theory of evolution by natural selection. The 
birds of Borneo, and of the Oriental region generally, 
have been developed in a larger area than those of the 
Moluccas and the Australian region, and having been 
subjected to a more severe struggle have developed 
higher and more aggressive types. Hence they are better 
adapted than the less developed Australian types for 
the colonisation of a large island, such as Celebes. But 
in the islets, where the very limited area can only support 
a small variety of forms, the immigrants from the Austra- 
lian region find conditions suitable to them, and they 
thus come to form a more prominent feature of the bird- 
population than in the main island. 

. Isolated Bird-types in Celebes.—It 1s, however, when 
we take note of the peculiar genera that we find the most 
interesting features of Celebes ornithology, some of them 
affording indications of great antiquity and long isolation. 
Four of these are considered by Dr. Meyer to be especially 
remarkable, and distinct from all known birds. These 
are: (1) the large and handsome Megacephalon, dis- 
tinguished by its horny crest and rosy under surface from 
all the other mound-makers; (2) the curious forest king- 
fisher Cittura, whose rosy and lilac colours on the head 
and throat resemble those of some of the butterflies of 
the same island. These two birds have their nearest 
allies in New Guinea. (3) Then we have Streptocitta, a 
bird something like a magpie, but intermediate in struc- 
ture between the crows and starlings ; while the Scissiros- 
trum (4) is a small bird with a thick curiously formed bill 
and peculiar ashy plumage, a very isolated form of 
starling, with no near relations in any part of the 
world. 

Hardly less isolated are the small hornbill, Rhabdotor- 
rhinus, whose only ally is the Philippine genus Penelopides, 
which may itself have been originally derived from 
Celebes. A remarkable bee-eater, Meropogon, is perhaps 
allied to the Malayan Nyctiornis. The small forest 
kingfisher, Ceycopsis, is somewhat intermediate between 


the Malayan Ceyx and the African Ispidina. A honey- 


{ 
q 


CHAP XxX CELEBES 4596 


sucker, Myza, belongs to a family which is confined to the 
Australian region, while Malia and Cataponera belong to 
the specially Oriental bulbuls and babblers. Enodes is a 
remarkable form of starling, while Charitornis, found only 
in the Sula Islands, and Gazzola, in the southern peninsula 
of Celebes, are allied to the magpies and jackdaws. 

Besides these there are some other genera which though 
not now confined to the Celebes group most probably 
originated there. The large and handsome kingfisher, 
Monachalcyon, is a type which was formerly considered to 
be limited to Celebes, but species in the Philippines-and 
Lombok are now placed in the same genus, and both may 
have been derived from the former island. The curious 
parrots of the genus Prioniturus, having the two middle 
feathers of the tail elongated with a spoon-shaped tip, 
only occur elsewhere in the most southern island of the 
Philippines, and these were almost certainly derived from 
Celebes, since the former islands afford no such proofs 
of antiquity as do the latter. In like manner, the fine 
crested starlings, Basilornis, though having an allied 
species in the island of Ceram, almost certainly originated 
in Celebes. 

We have here sixteen peculiar types which are either 
peculiar to Celebes or originated in it, and many of these 
are so remarkable or are so isolated as to suggest very 
great antiquity, and a long-continued separation from the 
adjacent lands and islands, to a much greater extent than 
now prevails. Dr. Meyer, however, thinks these pecu- 
liarities in no way remarkable, and that the most striking 
feature of Celebes is, “not that it has so many highly 
peculiar forms but so extremely few.” And he adds, that 
it has nothing to compare with a Dodo or Kiwi. This is 
quite true, but has little to do with the question. 
Celebes in not an ancient oceanic island like Mauritius or 
an extremely isolated land like New Zealand, but is closely 
surrounded on every side by acontinent and by large and 
rich islands. So far as I am aware there is no other 
island on the globe in any way similarly situated which 
exhibits such an amount of zoological peculiarity and so 
many remarkable characteristics in its chief forms of life, 


460 ISLAND LIFE PART II 


and this is the more noteworthy on account of the com- 
parative poverty of its types of birds. : 

Although the preponderance of affinity, especially in the 
case of 1ts 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 for- 
bidden to suppose that it ever formed a part of the old 
Asiatic continent, on account of the 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 characteristic of all tropical Asia. Such are 
the Timeliidee, or babblers, of which there are twenty- 
three genera in Borneo, and many more in the Oriental 
Region, but of which only a few species and one peculiar 
genus inhabit Celebes; the Pycnonotide, or bulbuls, ab- 
solutely ubiquitous in tropical Asia and Malaya, but almost 
unknown in Celebes; the Eurylemidz, or gapers, found 
everywhere in the great Malay Islands ; the Megaleemide, 
or barbets ; the Trogonide, or trogons; and the Phasianide, 
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 tothese six ubiquitous 
families, we must ask,—Is it possible, that, at the period 
when the ancestors of the peculiar Celebes mammals 
eritered the island, and when the forms of life, though 
distinct, cou!d not have been quite unlike those now living, 
it could have actually formed a part of the continent 
without possessing representatives of the greater part of 
these extensive and important families of birds? To get 
rid altogether of such varied and dominant types of bird- 
life by any subsequent process of submersion is more 
difficult than to exterminate mammalia; and we are 
therefore again driven to our former conclusion—-that the 
present land of Celebes has never (in recent geological 
times) been united to the Asiatic continent, but has re- 
ceived its population of Asiatic forms by migration across 


a & 


CHAP. XxX CELEBES : 461 


; “> 


Marrow seas and intervening islands. Taking into con- 
sideration the amount of affinity on the one hand, and the 
isolation on the other, of the Celebesian fauna, we may 
_ probably place the period of this earlier migration in the 
_ early part of the latter half of the Tertiary period, that is, 
in middle or late Miocene times. 
Celebes not Strictly a Continental Island —A study of the 
_ mammalia 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 these 
arboreal creatures are very liable to be carried across 
narrow seas on trees uprooted by earthquakes or floods. 
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 
period. The presence of the Celebes ape in the island of 
__ Batchian, and of the babirusa in Bourn, can be sufficiently 
_ 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 the peculiar features 
presented by the fauna of Celebes be the correct one, we 
are fully justified in classing it as an “ anomalous island,” 
since it possesses a small but very remarkable mammalian 
fauna, without ever having been directly united with any 
- continent or extensive land ; and, both by what it has and 
what it wants, occupies such an exactly intermediate 
position between the Oriental and Australian regions that 
it will perhaps ever remain a 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 Cacatuide, Tricho- 


a > 


462 ISLAND LIFE PART II 


glosside and Meliphagids among birds, and being so 
strikingly deficient in all the more characteristic Oriental 
families and genera of both classes, I at first placed it in 
the Australian Region; but as the larger portion of its 
mammals and birds have undoubtedly Asiatic affinites, 
it cannot be altogether excluded from the Oriental 
Region. 

Peculiarities of the Insects of Celebes.—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 remarable 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 (Ceographical Dis- 
tribution of Animals (Vol. I. p. 484)—I will only here 
briefly refer to them in order to see whether they ac- 
cord with, or receive any explanation from, the some- 
what novel view of the past history of the island here 
advanced. i 

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 
flycatcher (Culicicapa helianthea), a flower-pecker (Acmono- 
rhynchus awreolimbata), and a roller (Coracias temmanckit), 
all allied to Indian rather than to Malayan species. An 
exactly parallel case is that of a butterfly of the genus 


CHAP. XX CELEBES 463 

Dichorrhagia, 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 Colowr in Celebesian Butter- 
jives.—Even more remarkable are the peculiarities of shape 
and colour ina number of Celebesian 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 similar 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 Remarks.—If the view here given of the 
origin of the remarkable Celebesian fauna is correct, we 
have in this island a fragment or outlier of the great 
eastern continent which has preserved to us, perhaps 
from Miocene times, some remnants of its ancient animal 
forms. There is no other example on the globe of an 
island so closely surrounded by other islands on every 
side, yet preserving such a marked individuality in its 


1 For outline figures of the chief types of these butterflies, seemy Malay 
Archipelago, Vol. I. p. 441, or p. 216 of the tenth edition. 


ee rat) 
a 
J 


464 | ISLAND LIFE a 


forms of life; while, as regards the special features which 
characterise its insects, 1t 1s, so far as yet known, abso- _ 
lutely unique. Unfortunately very little research has yet 
been bestowed upon the botany of Celebes, but it seems 
probable that its plants will to some extent partake of the — 
specialty 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 and the adjacent islands 
which partake of its zoological peculiarities, in which are incorporated all 
the species discovered up to 1898, has been copied from Birds of Celebes, 
by Dr. A. B. Meyer and Mr. Wigglesworth, but so rearranged as to 
compare with the list of Bornean birds in an earlier chapter. 


LIsT OF THE J.AND BIRDS OF CELEBES. 


The inset names are from the Celebesian Islets only. The peculiar species 
can be known by a blank in the distribution column. Peculiar genera are 


in small cagntals. 


MEGAPODIIDA., 


1. Megapodius cumingi . 
1. M. sangirensis. 
2. M. bernsteini. 
3. M. duperreyi . 

2. MEGACEPHALON MALEO. 


PHASIANIDA. 


Gallus ferrugineus . 


. Turnix rufilatus. 
T. maculosa . 


D on > oO 


CoLUMBIDZ. 


7. Osmotreron wallacei. 
4, O. sangirensis. 
8. O. vernans . . 
9. Ptilopus fischeri. 
10. P. meridionalis. 
11. P. gularis. 
5. P. subgularis. 
6. P. melanocephalus 
12. P. melanospilus. 
7. P. chrysorrhous . 
8. P xanthorrhous, 


. Exeafaleatoria chinensis . 


DISTRIBUTION OUTSIDE CELEBES. 
Alsoin N. Borneo and Philippines. 


Also Pa puan. 


India and Malaya. 
India, Moluccas. 


Papua and Australia, 
India to Philippines. 


Also in Java. 


Also in Moluccas. 


466 


ISLAND LIFE 


PART II 


. P. temmincki ‘ 
. Carpophaga paulina. 


9. C. pulchella. 
10. C. concinna 
11. C. intermedia. 


. C. rosacea 


i Aas OF pickernigi 


. C. radiata. 

. C. forsteni. 

. C. pecilorrhoa. 

. Myristicivora bicolor . 
. M. luctuosa 

13. Columba albigularis . 
. Turaceena manadensis. 
. Macropygia albicapilla. 
. M. macassariensis. 

. Turtur tigrinus . 

. Geopelia striata . 


Chalcophaps indica 


. C. stephani . 

. Phlogeenas tristigmata. 
. P. bimaculata. 

_ Caleenas nicobarica 


FALCONIDA, 


. Spilornis rufipectus. 

. Circus assimilis. 

. Astur griseiceps. 

. A. trivirgatus 

14. Urospizias torquatus, 
. Tachyspizias soloensis. 

. SPILOSPIZIAS TRINOTATUS. 
. Accipiter rhodogaster. 


15. A. sulaensis. 


. A. virgatus, var. 

. Spizaétus lanceolatus. 
. Lophotriorchis kieneri. 
. Ictinaetus malayensis . 
. Haliaetus leucogaster . 
. Polioaetus humilis . 

. Butastur indicus 

. B. liventer 

. Haliastur indus. 

. Milvus migrans, var. . 
. Elaaus hypoleucus 

. Pernis celebensis 


6. Pe sp. 


. Baza celebensis. 


17. B. reinwardti . 


. Tinnunculus moluccensis. 
. Falco severus, var. 

. F. peregrinus, var. 

. Pandion haliaetus . 


DISTRIBUTION OUTSIDE CELEBES. 
Also in Philippines. 


Moluccas, Papua. 


Moluccas, Papua. 
Borneo, Phili ppines. 


India to Papua. 


Moluccas, Papua. 


India to Papua. 

India to Moluccas. 
India to Moluccas. 
Moluccas and Papua. 


India to Papua. 


Also in Australia. 


India, Borneo, Philippines. 
Papua, Australia, 
India to Papua. 


India to Philippines. 


India to Philippines. 
India, Borneo, &c. 
India to Australia. 
India to Borneo. 

India to Papua. 

India to Borneo. 

India to Australia. 
India to Australia. 
Sumatra to Philippines. 


Moluccas and Papua. 
Java, Borneo, Moluccas. 
Malacca to Moluccas. 
Cosmopolite, 
Cosmopolite. 


CHAP, xx LIST OF LAND BIRDS OF CELEBES 467 
ee ee ees eee 


STRIGIDA. DISTRIBUTION OUTSIDE CELEBES. 
55. Ninox ochracea. 
56. N. scutulata. India to Moluccas. 
57. Cephaloptynx punctulata. 
58 Scops manadensis . Moluccas. 
59. Strix flammea Cosmopolite. 
60. S. inexpectata. 
61. S. candida India, Philippines, Australia. 
PSITTACIDA. 

62. Trichoglossus ornatus. Australasian genus. 

18, T. forsteni, var. . Sumbawa (?). 
63. T. meyeri. 

19. T. flavoviridis. 

20. Eos histrio. Moluccan and Papuan genus. 
64, Cacatua sulphurea. Lombok to Timor. 


. Prioniturus platurus. 
. P. flavicans. 
. Tanygnathus muelleri. 


21. T. luconensis . 
22. T. talautensis. 


. T. megalorhynchus. 
. Loriculus exilis. 


23. L. sclateri. 


. L. stigmatus. 


24, L. quadricolor. 
25. L. catamene. 
26. Aprosmictus sulaensis. 


Moluccan genus. 
Philippines. 


Moluccas, Papua. 


CoRACIADZ. 
71. Coracias temmincki. 
72, Eurystomus orientalis. India to Australia. 
HALCYONID. 
. Alcedo ispida Europe to Moluccas. 
74, A. moluccana Moluccas, Papua. 
75. A. meninting ‘ India, Borneo and Philippines. 
76 Pelargopsis melanorhyne ha. 


27. P. dichrorhyncha. 
28. Ceyx wallacei . 


. CEYCOPSIS FALLAX. 


29. C. sangirensis. 


Allied to a Moluccan species. 


78. Halcyon coromanda, v. rufa. India to Borneo, 
79. H. pileata ; India, Borneo, Philippines. 
80. H. sancta. Sumatra to Polynesia. 

81. H. chloris . The whole archipelago. 

82. Monachalcyon monachus. 

83. M. capucinus. 

84. M. princeps. 

85. CITTURA CYANOTIS. 


30. C. sangirensis. 


468 


86. 
87. 


88. 
89. 
90. 


a1, 
a2. 
93. 
94. 


95. 


96. 
97. 
98. 
99. 


-100. 
101. 
102. 
103. 
104, 
105. 
106. 
107. 
108. 
109. 
110. 


Ad1. 
112. 
118. 
114. 


115. 
116. 
ity. 


118. 


ISLAND LIFE — 


BUCEROTIDZ. 


RHABDOTORRHINUS EXARATUS.. 


Cranorhinus cassidix. 


MEROPIDZ. 


Merops ornatus 
M. philippinus ; 
MEROPOGON FORSTENI. 


CAPRIMULGIDA. 


Caprimulgus macrurus, var. 
C. celebensis. 

C. affinis : : 
Lyncornis macropterus. 


CYPSELIDZ. 


Cheetura celebensis 
31. Cypselus pacificus 
Collocalia fuciphaga’ . 
C. esculenta. 

C. francica 
Macropteryx wallacei. 


CUCULIDA. 


Hierococcyx crassirostris. 
H., sparverioides . 

H. fugax 

Cuculus canorus, var. 
Chrysoccoccyx malayanus . 
C. basalis - . ; 
Cacomantis virescens 

C. merulinus . ; 
Coccystes coromandus . 
Surniculus musschenbroeki 
Eudynamis melanorhyncha. 
32. E. mindanensis : 
Centrococcyx bengalensis . 
Pyrrhocentor celebensis. 


Pheenicophaes calorhynchus. 


Scythrops novehollandiz 


PIcID. 


Jyngipicus temmincki, 
Microstictus fulvus, 
M. wallacei. 


PITTIDA. 


Pitta celebensis. 
33. P. palliceps. 


DISTRIBUTION OUTSIDE CELEBES. 


Moluccas, Lombok, Australia. 
India, Borneo. Philippines. 


Malacca to Philippines. 


Malacca to Borneo, 


Also in Philippines. 
Papua, Australia. 
India to Polynesia. 
Moluccas to Australia. 
India to Polynesia. 


India, Borneo, Philippines. 
China, Borneo, Philippines. 
India to Polynesia. 
Malacca to Australia. 
Malacca to Australia. 


India, Borneo, Philippines. 
India, Borneo, Ragen . 
Moluccas: 

a a - 

India to Moluccas. 


Moluccas, Timor, Australia. 


“PART II 


CHAP. xXx 


34. P. ceruleitorques. 

35. P. inspeculata. 
119, P. forsteni. 

36, P. sangirana. 
120. P. cyanoptera. 

37. P. irena 

38. P. virginalis. 


ARTAMIDA, 


121. Artamus leucogaster. 
122. A. monachus. 


STURNIDA. 


123. Calornis age var. 
124. C. minor a 
125. C. sulaensis. 
39. C. metallica . 
126. ENODES ERYTHROPHRYS 
127. Acridotheres cinereus. 
128. SCISSIROSTRUM DUBIUM. 
129. Sturnia violacea . 
130. Basileornis celebensis. 
40. B. galeatus. 


CoRVIDA. 


131. STREPTOCITTA ALBICOLLIS. 


132. S. torquata. 


41. CHARITORNIS ALBERTINZ. 


133. Corvus enca, var. 
134. GAZZOLA TYPICA. 


PLOCEIDA. 


135. Munia oryzivora . 


136. M. formosana, var. brunneiceps. 


137. M. pallida. 

138. M. subcastanea. 
139. M. punctulata 
140. M. molucca 


- FRINGILLIDA. 


141. Passer montanus. 


ZOSTEROPIDE. 


142. Zosterops squamiceps. 
143. Z. intermedia . 
144, Z. atrifrons. 
42. Z. subatrifrons. 
43. Z. nehrkorni. 


LIST OF LAND BIRDS OF CELEBES 469 


DISTRIBUTION OUTSIDE CELEBES, 


India, Borneo. 
Moluccas. 


India to Australia. 


India to Borneo. 
Lombok to Timor. 


Moluccas to Australia. 


Borneo, Philippines, Molucea. 


Java, 


India to Borneo, Philippines. 
Formosa, Borneo, Philippines. 


Malacca, Java, Papua. 
Moluccas, Papua. 


Europe to Malacca and Philip- 
pines. 


Also Moluccas, Lombok. 


470 


145. 
146. 


147. 


148. 
149. 
150. 
151. 


152. 


153. 
154. 
155. 
156. 


157 


158. 
159. 


160. 


161. 
162. 


163. 
164. 
165. 
166. 


167. 
168. 
169. 
170. 


ISLAND LIFE 


Z. sarasinorum. 
Z. anomala. 
44. Z. habels. 


DICAIDZA. 


Diceum celebicum. 
45. D. sulaense. 
46. D. sangirense. 
47. D. talautense. 
D. splendidum. 
D. nehrkorni. 

D. hosel. 


48. A. sangirensis. 


NECTARINIIDA. 


Aethopyga flavostriata. _ 
49. Eudrepanis duivenbodii. 
50. Cyrtostomus frenatus 
Cyrtostomus teijsmanni. 
Hermotimia auriceps 

H. porphyrolaema. 

H. grayi. 

51. H. sangirensis. 

52. H. talautensis. 

. Anthreptes maleccensis, var 
Myzomela chloroptera. 
Melilestes celebensis. 


MELIPHAGIDA. 
MyYZA SARASINORUM. 


HIRUNDINIDA. 


Hirundo rustica . 
H. javanica 


MOTACILLIDA. 


Motacilla flava 
M. boarula. 
Anthus gustavi 
A. cervinus 


MUSCICAPIDA. 


Muscicapa griseosticta . 
Mascicapula westermanni . 
M. hyperythra..,) -. 
Siphia banyumas . 

53. S. djampeana. 

54. S. kalaoensis. 


Acmonorhynchus aureolimbatus. 


DISTRIBUTION OUTSIDE CELEBES. 


Moluccas to Australia. 


Moluccas to Papua. 


India to Borneo. 


Widespread. 
India to Australia. 


Europe to Moluccas. 

Europe to Papua. 

China to Borneo, Moluccas. 
Europe to Borneo, Philippines. 


. China, Philippines, Papua. 


India, Borneo, Philippines. 
India to Borneo. 
Java. 


PART if 


CHAP. xx LIST OF LAND BIRDS OF CELEBES 470a 
re ee 


DISTRIBUTION OUT , 

171. S. rufigula. aah ak Oa cae 
172. S. bonthaina. : 
173. Stoparola septentrionalis, 
174. S. meridionalis. 
175. Hypothymis puella. 

55. H. rowleyi. 
176. Rhipidura celebensis. 
177. R. teijsmanni. 

56. Zeocephus talautensis, 
178. Monarcha commutatus. 


57. M.inornatus. . . . . . Moluccas, Papua 
58. M. everetti. 
59. Myiagrarufigula. . . . . Timor. 


179. Culicicapa helianthea. 


CAMPOPHAGIDA. 


180. Graucalus bicolor. 
181. G. leucopygius. 
182. G. temmincki. 
60. G. schistaceus. 
61. G. melanops . . . . . . Moluccas to Polynesia, 
183. Edoliisoma morio, 
62. E. salvadorii. 
63. KE. talautensi. 
64, KE. emancipata. 
Senos —. Obiense. . . . . . . Moluccas. 
184. Lalage leucopygialis. 
Meee. timorensis . .. . . . . Timor. 


DICRURIDZ. 


186. Dicrurus leucops. 
OG. DD. pectoralis . . . . . . Moluccas, 


LANIIDA. 


187. Pachycephala sulfuriventer. 
188. P. meridionelis. 


67. P. teijsmanni. 

68. P. orpheus. 

jeer. etisconota . . . . . . Moluccas, 
meetocio . . . . . . . « Moluccas, 
41. P. everetti. 

72. P. bonthiana. 


189. P. bonensis, 
73. Colluricinela sangirensis. 


190. Lanius tigrinus . . . . . . India, Borneo, Philippines. 
191. L. lucionensis. .. . . . . India, Borneo, Phil., Moluccas, 
ORIOLIDA, 


192. Oriolus celebensis. 
74. O. frontalis. 
75. O. boneratensis. 


I I 


470b ISLAND LIFE PART II 


DISTRIBUTION OUTSIDE CELEBES. 
76. O. formosus. 
77. O. melanisticus. 


BRACHYPODIDA. 


78. Tole aurea. 

79. I. longirostris. 

80. I. platen. 

81. MALIA GRATA. 
193. Androphilus castaneus. 
194. CATAPONERA TURDOIDES, 
_ 195. Trichostoma celebensis. 

196. T. finschi. 

197. Malacopteron affine. 


TURDIDA. 


198. Geocichla erythronota. 
199. Merula celebensis 


200. Petrophila cyanus, var. . -. . India, China, Moluccas. 
201. Cisticolacursitans . . - . . India to Java, Philippines. 
202. CVexilis, “oa aed a. 4) «5 Indiaitp Amaiwaiig. 
203. Phyllergates riedeli. 
204. Acrocephalus orientalis. . . . India to Moluccas. 

82. Locustella fasciolatx. . . China, Philippines, Moluccas. 
205. Locustella ochotensis . . . , China, Borneo, Philippines. 
206. Phylloscopus borealis . . . . India to Moluccas. 


207. Cryptolopha sarasinorum. 


CHAPTER XXI 


ANOMALOUS ISLANDS: NEW ZEALAND 


Position and Physical Features of New Zealand—Zoological Character of 
New Zealand—Mammalia— Wingless Birds Living and Extinct—Recent 
Existence of the Moa—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 mtroduce 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 definite 
conclusions as to the nature and origin of this remarkable 
fauna and flora. The present work is, besides, addressed 
to a wider class of readers than my former volumes, and 
it would be manifestly incomplete if all reference to one 
of the most remarkable and interesting of insular faunas 
was omitted. 

The two great islands which mainly constitute New 
Zealand are together about as large as the kingdom of 
Italy. They stretch over thirteen degrees of latitude in 
the warmer portion of the south-temperate zone, their 
extreme points corresponding to the latitudes of Vienna 
and Cyprus. Their climate throughout is mild and 


Eis 


472 ISLAND LIFE PART II 
equable, their vegetation is luxuriant, and deserts or 
uninhabitable regions are as completely unknown as in 
our own islands. 

The geological structure of these islands has a decidedly 
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 


MAP SHOWING DEPTHS OF SEA AROUND AUSTRALIA AND NEW ZEALAND, 


The light tint indicates a depth of less than 1,000 fathoms. 
The dark tint es “ 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 position of New Zealand, in the great Southern 
Ocean, about 1,200 miles distant from the Australian 


pe 


= 


CHAP, XXI . NEW ZEALAND 473 


continent, is very isolated. It is surrounded by a moder- 
ately deep ocean; but the form of the sea-bottom is 
peculiar, and may help us in the solution of some of the 
anomalies presented by its living productions. The line 
of 200 fathoms encloses the two islands and extends their 
area considerably; but the 1,000-fathom line, which in- 
dicates the land-area that would be produced if the sea- 
bottom were elevated 6,000 feet, has a very remarkable 
conformation, extending in a broad mass westward and 
northward, then sending out a great arm reaching to 
beyond Lord Howe’s Island. Norfolk Island is situated 
on a moderate-sized bank, while two others, much more 
extensive, to the north-west approach the great barrier 
reef, which here carries the 1,000-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 other 
hand, is divided from New Zealand by an oceanic gulf 
about 700 miles wide and between 2,000 and 3,000 fathoms 
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 south- 
ward to the Antarctic continent. Judging from these 
indications, we should say that the most probable ancient 
connections of New Zealand were with 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 shall 
find that a land-connection or near approximation in these 
two directions, at remote periods, will serve to explain 
many of the remarkable anomalies which these islands 
present. 

Zoological Character of New ZLealand.—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 1s 
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 predominant or close rela- 
tion to those of Australia or any other continent. These 
are the characteristics of an oceanic island; and thus 
we find that the inferences from its physical structure 
and those from its forms of life directly contradict each 
other. Let us see how far a closer examination of the latter 
will enable us to account for this apparent contradiction. 

Mammalia of New Lealand—The only undoubtedly 
indigenous mammalia appear to be two species of bats, 
one of which (Scotophilus tuberculatus) is, according to 
Mr. Dobson, identical with an Australian form, while the 
other (Mystacina tuberculata) forms a very remarkable 
and isolated genus of Emballonuride, a family which 
extends throughout all the tropical regions of the globe. 
The genus Mystacina was formerly considered to belong 
to the American Phyllostomidz, 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 
Kuropean 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 


1 Dobson on the Classification of Chiroptera (Ann. and Mag. of Nat. 
Hist, Nov. 1875). 


CHAP. XXI NEW ZEALAND 475 


often find their way on board ships. But within the last 
few years many skulls of a rat have been obtained from the 
old Maori cooking-places, and from a cave associated with 
moa bones ; and Captain Hutton, who has examined them, 
states that they belong to a true Mus, but differ from the 
Mus rattus. ‘This animal might have been on the islands 
when the Maoris first arrived, and in that case would be 
truly indigenous ; while 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 mammal which 
they knew—the dog—was certainly so brought. The 
question can only be settled by the discovery of remains of 
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 our 
European otter, at a height of 3,000 feet above the sea in 
a region never before trodden by man; and the animal 
itself was 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 yelping 
sound and disappeared in the water.?, An animal seen so 
closely as to be struck at with a whip could hardly have 
been mistaken for a dog—the only 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 and streams, 
this might explain why it has never yet been captured. 
Hochstetter also states that it has a native name— Waitoteke 
—a striking evidence of its actual existence, while a gentle- 
man who lived many years in the district assures me that 


1 See Buller, ‘‘ On the New Zealand Rat,” Trans. of the N. Z. Institute 
(1870), Vol. III. p. 1, and Vol. IX. p. 348 ; and Hutton, ‘‘ On the Geogra- 
phical Relations of the New Zealand Fauna,” Trans. N. Z. Instit. 1872, 

. 229. 
2 Hochstetter’s New Zealand, p. 161, note. 


476 ISLAND LIFE PART II 


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, Lwing 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 belong to the 
subclass Ratitze, which includes the ostriches and 
cassowaries, but they form a distinct order, 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 

1 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 itis. 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 which ‘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 animal in New Zealand of corresponding size and 


colour is confirmed -by this account of a similar animal having been seen 
about a century ago. 


CHAP. XXI NEW ZEALAND 477 
RES A IERE SORE 9D CaeSE pee Wert Pos aVEN rao SEA ieee ee A NR am The: 


of Dinornis maximus mounted in the British Museum in 
its natural attitude being eleven feet high. They agreed, 
however, with 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 the 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 Kuropeans.? Bones of Apteryx are also found 
fossil, but apparently of the same species as the living birds. 


7 Owen, ‘‘On the Genus Dinornis,” Trans. Zool. Sor, Vol. X. p. 184. 
Mivart, ‘‘On the Axial Skeleton of the Struthionide,” Z’rans. Zool. Soc. 
mon A. 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 
the natives for thirty-five years, who has been initiated by their priests into 
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 on 
the subject arose. He says that the histories and songs of the Maoris 
abound in allusions to the Moa, and that they were able to give full 
accounts of ‘‘its habits, food, the season of the year it was killed, its 
appearance, strength, and all the numerous ceremonies which were enacted 
by the natives before they began the hunt, the mode of hunting, how cut 
up, how cooked, and what wood was used in the cooking, with an account 
of its nest, and how the nest was made, where it usually lived, &c.” Two 
' pages are occupied by these details, but they are only given from memory, 
and Mr. White promises a full account from his MSS. Many of the details 
given correspond with facts ascertained from the discovery of native cook- 
ing places with Moas’ bones ; and it seems quite incredible that such an 
elaborate and detailed account should be all invention. (See Transactions 
of the New Zealand Institute, Vol. VIII. p. 79.) 


478 ISLAND LIFE PART 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 specimens 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 approximation to the time required for the 
origin and development of such highly peculiar insular 
forms. 

Past Changes of New Zealand deduced from its Wingless 
Birds—lIt has been well observed by Captain Hutton, in 
his interesting paper already referred to, that the occurrence 
of such a number of species of wingless 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 swamp in the South Island, 
where also three of the species of Apteryx occur. The 
New Zealand Ratite, 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 Rhea, each 
in a separate district. Australia has an eastern and a 
western variety of emu, and a cassowary in the north; while 
eight other cassowarles 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 part of the island. 

This law, of the distribution of allied species in separate 
areas—which is found to apply more or less accurately to 
all classes of animals—is so entirely opposed to the crowding 
together of no less 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 


“ 
— =~ 


al ¢ ay ee EL oes i . Di vt 


oe eh 


a eT 


a 


Pn ee TOES ee Le 
| ’ iw we .¢ “) a 


CHAP. XXxI NEW ZEALAND 479 
were to become joined together, we should have a large 
number of species of cassowary (perhaps several more than 
are yet discovered) in one land area. If now this land 
were gradually to be submerged, leaving a central elevated 
region, the different species would become crowded together 
in this portion just as the moas and kiwis were in New 
Zealand. But we also require, at some remote epoch, a more 
or less complete union of the islands now inhabited by the 
separate species of cassowaries, in order that the common 
ancestral form which afterwards became modified into these 
species, could have reached the places where they are now 
found ; and this gives us an idea of the complete series of 
changes through which New Zealand is believed to have 
passed in order to bring about its abnormally dense popula- 
tion of wingless birds. First, we must suppose a land connec- 
tion with some country inhabited by struthious birds, from 
which the ancestral forms might be derived; secondly, a 
separation into many considerable islands, in which the 
various distinct species might become differentiated ; 
thirdly, an elevation bringing about the union of these 
islands to unite the distinct species in one area; and 
fourthly, a subsidence of a large part of the area, leay- 
ing the present islands with 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- 
sumably, 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 
wholly concur ; but we cannot follow him when he goes on 
to suggest an Antarctic continent uniting New Zealand and 
Australia with South America, and probably also with 
South Africa, in order to explain the existing distribution 


480 ISLAND LIFE PART II 


of wingless birds. Our best anatomists, as we have seen, 
agree that both Dinornis and Apteryx are more nearly 
allied to the cassowaries and emus than to the ostriches 
and rheas; and we see that the form of the sea-bottom 
suggests a former connection with North Australia and 
New Guinea—the very region where these types most 
abound, and where in all probability they originated. The 
suggestion thatall the great wingless 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 now 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, that 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 ostrichesin 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 


CHAP. xxI NEW ZEALAND 481 


plumes. In the cassowary these wing-feathers are reduced 
to long spines like porcupine-quills, while even in the 
Apteryx, the minute external wing bears a series of nearly 
twenty stiff quill-like feathers! These facts render it 
almost certain that the Ratite birds do not owe their 
imperfect wings to a direct evolution from a reptilian type, 
but to a retrograde development from some low form of 
winged birds, analogous to that which has produced the 
dodo and the solitaire from the more highly-developed 
pigeon-type. Professor Marsh has proved, that so far back 
as the Cretaceous period, the two great forms of birds— 
those with a keeled sternum and fairly-developed wings, 
and those with a convex keel-less sternum and rudimentary 
wings—already existed side by side; while in the still 
earlier Archzopteryx of the Jurassic period we have a bird 
with well-developed wings, and therefore probably 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 birds 
acquired wings, and feathers, and some power of flight, 
before they developed a keeled sternum, since we see that 
bats with no such keel fly very well. Since, therefore, the 
struthious birds all have perfect feathers, and all have 
rudimentary wings, which 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 the very remote 
ancestors of the rhea, the cassowary, and the apteryx, were 
true flying birds, although not perhaps provided with a 
keeled sternum, or possessing very great powers of flight. 
But in addition to the possible ancestral power of flight, 
we have the undoubted fact that the rhea and the emu 
both swim freely, the former having been seen swimming 
from island to island off the coast of Patagonia. This, 
taken in connection with the wonderful aquatic ostrich of 
the Cretaceous period discovered by Professor Marsh, opens 


1 See fig. in Trans. of N. Z. Institute, Vol. III., plate 120. fig. 2. 


482 ISLAND LIFE PART II 
up fresh possibilities of migration; 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 now 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, by way of a southern 
continent or antarctic islands, with South America and 
South Africa, because the nearest, though still remote, 
allies of its moas and kiwis are the cassowaries and emus, 
and we have distinct indications of a former land extension 
towards North Australia and New Guinea, which is exactly 
what we require for the original entrance of the struthious 
type into the New Zealand area. 

Winged Birds and Lower Vertebrates of New ZLealand.— 
Having given a pretty full account of the New Zealand 
fauna elsewhere! I need only here point 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 the temperate regions of Australia. 

Of the Australian genera of birds, which are found also 
in New Zealand, almost every one ranges also into New 
Guinea or the Pacific Islands, while the few that do not 
extend beyond Australia are found in its northern dis- 
tricts. As regards the peculiar New Zealand genera, all 
whose affinities can be traced are allied to birds which 
belong to the tropical parts of the Australian region; 
while the starling family, to which four of the most 
remarkable New Zealand birds belong (the genera 
Creadion, Heterolocha, and Calleas), is totally wanting 
in temperate Australia and is comparatively scarce in 
the entire Australian region, but is abundant in the 
Oriental region, with which New Guinea and _ the 
Moluccas are in easy communication. It is certainly 
a most suggestive fact that there are more than sixty 

1 Geographical Distribution of Animals, Vol. I., p. 450. 


CHAP. XxXI NEW ZEALAND 483 


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 one 
of these should be represented in temperate New Zea- 
land." The affinities of the living and more highly 
organised, no less than those of the extinct and wine- 
less birds, strikingly accord with the line of communz- 
cation indicated by the deep submarine bank connecting 
these temperate islands with the tropical parts of the 
Australian region. 

The reptiles, so far as they go, are quite in accordance 
with the birds. The lizards belong to 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—Geckonidx 
—spread over the whole of the warmer parts of the world. 
Australia, 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 
Hatteria 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 with any living animal. 

The only representative of the Amphibia in New 
Zealand is a solitary frog of a peculiar genus (Liopelma 
hochstetteri); but it has no affinity for any of the 
Australian frogs, which are numerous, and belong to 
eleven different families; while the Liopelma belongs 

1 In my Geographical Distribution of Animals (I. p. 541) I have given 
two peculiar Australian genera (Orthonyx and Tribonyx) as occurring in 
New Zealand. But the former has been found in New Guinea, while the 
New Zealand bird is considered to form a distinct genus, Clitonyx ; and 


the latter inhabits Tasmania, and was recorded from New Zealand through 
an error. (See Jbis, 1873, p. 427.) 

* The peculiar genera of Australian lizards according to Boulenger’s 
British Museum Catalogue, are as follows :—Family GECKONIDZ& : Neph- 
rurus, Rhynchcedura, Heteronota, Diplodactylus, Gidura. Family Pyco- 
PODID# (peculiar): Pygopus, Cryptodelma, Delma, Pletholax, Aprasia. 
Family AGAMID#: Chelosania, Amphibolurus, Tympanocryptis, Diporo- 
phora, Chlamydosaurus, Moloch, Oreodeira. Family Scincrp# : Egerina, 
Trachysaurus, Hemisphenodon. Family doubtful : Ophiopsiseps. 


484 ISLAND LIFE PART II 


to a very distinct family (Discoglosside), confined to 
the Palearctic region. 

Of the fresh-water fishes. we 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 


CHAP. XxXI NEW ZEALAND 485 


the Bampton 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 we have no means of ascertaining, but as the 
intervening sea appears to be not more than about 1,500 
fathoms deep it 1s 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 of 
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 species 
of these birds in a small area but of which we have no 
independent proof. There are, however, some other facts 
which would be explained by it, as the presence of three 
peculiar but allied genera of starlings, the three species of 
parrots of the genus Nestor, and the six distinct rails of 
the genus Ocydromus, as well as the numerous species In 
some of the peculiar New Zealand genera of plants, which 
seem less likely to have been developed in a single area 
than when isolated, and thus preserved from the counter- 
acting influence of intercrossing. 

In the present state of our knowledge these seem all 
the conclusions we can arrive at from a study of the New 
Zealand fauna; but as we fortunately possess a tolerably 

K K 


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 are 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. 


CHAPTER XXII 


THE FLORA OF NEW ZEALAND: ITS AFFINITIES AND 
PROBABLE ORIGIN 


Relations of the New Zealand Flora to that of Australia—General Features 
of the Australian Flora—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. 


ALTHOUGH plants have means of dispersal far exceeding 
those possessed by animals, yet as a matter of fact com- 
paratively few species are carried for very great distances, 
and the flora of a country taken as a whole usually affords 
trustworthy indications of its past history. Plants, too, are 
more numerous in species than the higher animals, and are 
almostalways better known ; their affinities have been more 
systematically studied ; and it may be safely affirmed that 
no explanation of the origin of the fauna of a country can 
be sound,which does not also explain, or at least harmonise 
with, the distribution and relations of its flora. The dis- 
tribution of the two may be very different, but both should 
be explicable by the same series of geographical changes. 

The relations of the flora of New Zealand to that of 
Australia have long formed an insoluble enigma for botan- 
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 

KR 2 


488 ISLAND LIFE PART 11 


—_—-~—— 


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 migra- 
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 1s 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 such 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 whatever 
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 diff- 
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 Handbook of the New 
Zealand Flora. 
Since this was published, however, botanical exploration 
has been active in New Zealand, and Mr. W. B. Hemsley 
states in 1894, that 550 new species of flowering plants 
had been described, which, in addition to the 935 in the 
Handbook, would make a total of 1,485 species ; but he is 
of opinion that a considerable proportion of these do not 
rank on an equality with the species of the Handbook, so 
that the actual number of known species will be very 
much less. But the chief interest of the New Zealand 
flora is in the affinities of the genera, and as very few new 
genera have been added, the general conclusions drawn 


CHAP. XXII THE FLORA OF NEW ZEALAND 489 
from the facts presented by the Handbook will not be 
materially affected by the more recent discoveries. 

Even if we accept the full number of species above 
given, the flora cannot be considered to be a rich one, 
since the area of the islands is about one-sixth larger than 
that of Great Britain, with the immense advantage of 
extending from a temperate to a sub-tropical latitude, and 
possessing magnificent ranges of snowy mountains. Yet 
the number of its flowering plants will probably not 
surpass our own. 

Owing to its extremely isolated position an unusually 
large proportion of its species of plants are peculiar, and 
there are also between thirty and forty peculiar genera. Of 
about three hundred species which are common to other 
countries, rather more than three-fourths are Australian, 
but a considerable number of these are also Antarctic, South 
American or European; so that there are only about 100 
species absolutely confined to New Zealand and Australia, 
and, what is important as indicating 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 important Australian genera. 
Many, too, are rare species in both countries and are often 
alpines. | 

Far more important are the relations of the genera and 
families of the two countries. All the Natural Orders of 
New Zealand are found in Australia except three—Coriarie, 
a widely-scattered group found in South Europe, the 
Himalayas, and the Andes; Escalloniez, a subdivision 
of the Saxifragacee; and Chloranthacee, found in 
Tropical Asia, Japan, Polynesia, and South America. Out 
of a total of 315 New Zealand genera, no less than about 
255 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— 
Composit, Orchidese, and Graminex, the genera are 


1 These figures are taken from Mr. G. M. Thomson’s address ‘‘On the 
Origin of the New Zealand Flora,” Trans. N. Z. Institute, XIV. (1881), 
being the latest that I can obtain. They differ somewhat from those given 
in the first edition, but not so as to affect the conclusions drawn from 
them. 


490 ISLAND LIFE PART II 


almost identical in the two countries, while the species— 
in the two former especially—are mostly distinct. 

Here then we have apparently a wonderful resemblance 
between the New Zealand flora and that of Australia, in- 
dicated by more than two-thirds of the non-peculiar species, 
and more than nine-tenths of the non-peculiar genera (255) 
being Australian. But now let us look at the other side 
of the question. 

There arein Australia seven great genera of plants, each 
containing more than 100 species, all widely spread over 
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 species of Leucopogon, a genus which 
also has representatives in the Malayan and Pacific Islands. 
Sixteen more Australian genera have over fifty species 
each, and of these eight are totally absent from New 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 
reached 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—Dilleniacez, Buettneriacez, Polygalee, 
Tremandree, Casuarineze, Heemodoraceze, and Xyridez are 
entirely wanting in New Zealand, and several others which 
are excessively abundant and highly characteristic of the 
former country are very poorly represented in the latter. 
Thus, Leguminosz are extremely abundant in Australia, 
where there are about 1,100 species belonging to nearly 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 Goodeniaceze with ten genera and 220 

1 This accords with the general scarcity of Leguminose in Oceanic 


Islands, due probably to their usually dry and heavy seeds, not adapted to 
any of the forms of aérial transmission ; and it would indicate either that 


YY 7 te te 


CHAP. XXII THE FLORA OF NEW ZEALAND 491 
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 
—Rhamnez, Myoporinee, Proteace and Santalacez, have 
very few representatives in New Zealand. 

We find, then, that the great fact we have to explain 
and account for is, the undoubted affinity of the New Zea- 
land flora to that of Australia, but an affinity almost ex- 
clusively confined to the least predominant and least 
peculiar portion of that flora, leaving the most predominant, 
most characteristic and most widely distributed portion 
almost wholly unrepresented. We must however be care- 
ful not to exaggerate the amount of affinity with Australia, 
apparently implied by the fact that nearly six-sevenths of 
the New Zealand genera are also Australian, for, as we 
have already stated, a very large number of these are 
European, Antarctic, South American or Polynesian genera, 
whose presence in the-two contiguous areas only indicates 
a common origin. About one-eighth, only, are absolutely 
confined to Australia and New Zealand (thirty-two genera), 
and even of these several are better represented in New 
Zealand than in Australia, and may therefore have passed 
from the former to the latter. No less than 174 of the 
New Zealand genera are temperate South American, many 
being also Antarctic or European ; while others again are 
especially tropical or Polynesian ; yet undoubtedly a larger 
proportion of the Natural Orders and genera are common 
to Australia than to any other country, so that we may say 
that the basis of the flora is Australian with a large inter- 
mixture of northern and southern temperate forms and | 
others which have remote world-wide affinities. 

General Features of the Australian Flora and its Probable 
Origin——Before proceeding to point out how the 
peculiarities of the New Zealand flora may be best 
accounted for, it is necessary to consider briefly what are 
the main peculiarities of Australian vegetation, from which 
so important a part of that of New Zealand has evidently 
been derived. 


New Zealand was never absolutely united with Australia, or that the union _ 
was ata very remote period when Leguminose were either not differentiated 
or comparatively rare. 


492 ISLAND LIFE PART II 


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. 
All that is most characteristic of the Australian flora 
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 most other countries, the 
tropical appears to be less rich in species and genera than 
the temperate 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 species are 


1 Sir Joseph Hooker informs me that the number of tropical Australian 
plants discovered within the last twenty years is very great, and that the 
statement as above made may have to be modified. Looking, however, at 
the enormous disproportion of the figures give in the ‘‘ Introductory 
Essay” in 1859 (2,200 tropical to 5,800 temperate species) it seems hardly 
possible that a great difference should not still exist, at all events as 
regards species. In Baron von Miieller’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 West Australia, and 3,251 in 
New South Wales. On counting the species common to these two colenies 
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, we 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 will 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 
full 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°8. Lat. as 
against temperate Africa and Europe up to 47°—I suspect that the latter 
would present more genera and species than the former.” This, however, 
appears to me to be hardly a case in point, because Europe is a distinct con- 
tinent from Africa and has had a very different past history, and it is nota 
fair comparison to take the tropical area in one continent while the temperate 
is made up of widely separated areas in two continents. A closer parallel 
may Strat be found in equal areas of Brazil and south temperate America, 
or of Mexico and the Southern United States, in both of which cases I 


CHAP. XXII THE FLORA OF NEW ZEALAND 493 


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 
Australia which range over the whole continent, but these 
form onlyasmall portion of the peculiarly Australian genera. 

These 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 warm-temperate Australia, and 
such as were best adapted to the tropical climate and arid 
soil, would intermingle with them. Even if numerous 
islands had occupied the area of Northern Australia for 
long periods anterior to the final elevation, very much the 
same state of things would 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 thisisolationisexactly what was required, 
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 regards its 
component parts and probable past history. 

The Floras of South-eastern and South-western Australia. 
—The peculiarities presented by the south-eastern and 


suppose there can be little doubt that the tropical areas are far the richest. 
Temperate South Africa is, no doubt, always quoted as richer than an 
equal area of tropical Africa or perhaps than any part of the world of equal 
extent, but this is admitted to be an exceptional case. 


494 ISLAND LIFE PART II 


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, with 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 
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 1t has a large number altogether 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.” 

Geological Explanation of the Differences of these Two 
Floras.—These facts again clearly point to the conclusion 
that South-western Australia is the remnant of the more 

1 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 preced- 
ing note indicate that this isso. But still, the small area of South-west 
Australia will be, proportionally, far the richer of the two. It is much to 
be desired that the enormous mass of facts contained in Mr. Bentham’s 
Flora Australiensis and Baron von Miieller’s Census 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 THE FLORA OF NEW ZEALAND 495 


extensive and more isolated portion of the continent in 
which the peeuliar Australian flora was principally 
developed. ‘The existence there of a very large area of 
granite—800 milesin length by nearly 500 in maximum 
width with detached masses 200 miles to the north and 
500 miles to the east—indicatessuchanextension; for these 
granitic masses were certainly once buried under piles of 
stratified rock, since denuded, and then formed the nucleus 
of the old Western Australian continent. If we take the 
1,000-fathom line around the southern part of Australia tu 
represent the probable extension of this old land we shall see 
that it would give a wide additional area south of the Great 
Australian Bight, and form a continent which, even if the 
greater part of tropical Australia were submerged, would be 
sufficient for the development of a peculiar and abundant 
flora. We must also remember that an elevation of 6,000 
feet, added to the vast amount which has been taken away 
by denudation, would change the whole country, including 
what are now the deserts of the interior, into a mountain- 
ous and well-watered region. 

But while this rich and peculiar flora was in process of 
formation, the eastern portion of the continent must either 
have been widely separated from the western or had 
perhaps not yet risen from the ocean. The whole of this 
part of the country consists of Paleozoic and Secondary 
formations with granite and metamorphic rocks, the 
Secondary deposits being largely developed on both sides 
of the central range, extending the whole length 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 Secondary 
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 western 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 in 


496 ISLAND LIFE PART II 


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 first 
existed as separate islands, and only became united at a 
comparatively recent epoch. This is indicated by an 
enormous stretch of Cretaceous and Tertiary formations 
extending from the Gulf of Carpentaria completely across 
the continent to the mouth of the Murray River. Durin 
the Cretaceous period, therefore, and probably throughout 
a considerable portion of the Tertiary epoch,! there must 
have been a wide arm of the sea occupying this area, 
dividing the great mass of land on the west—the true seat 
and origin of the typical Australian flora—from a long but 
narrow belt of land on the east, indicated by the continuous 
mass of Secondary and Paleozoic 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 western island, almost or quite extra- 
tropical, and extending from the Silurian rocks of the Flin- 
ders range in South Australia, toabout 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. 


1 From an examination of the fossil corals of the South-west of Victoria, 
Professor P. M. Duncan concludes—‘“‘ that, at the time of the formation of 
these deposits the central area of Australia was occupied by sea, having 
open water to the north, with reefs in the 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 Geol. 
Soc., 1870.) 


CHAP. XXII THE FLORA OF NEW ZEALAND 497 


The eastern and the western island—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 
peculiar Australian flora, and also the ancestral forms of 
its strange marsupial fauna both of which it had probably 


. 
4s 
oss 


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Mm ; 
$ 

ys. 
3 - , 
© Mein it 

XN 

. 

. 


- 
Pmt 


seinen | 


“sae eee” 


M3LINVUMY 


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cs 


Walker & Boutall sc. 


MAP SHOWING THE PROBABLE CONDITION OF AUSTRALIA DURING THE CRETACEOUS 
AND EARLY TERTIARY PERIODS. 


The white portions represent land ; the shaded parts sea. 
The existing land of Australia is shown in oytline. 


received at some earlier epoch by a temporary union with 
the Asiatic continent over what is now the Java sea. 
Eastern Australia, on the other hand, possessed only the 
rudiments of its existing mixed flora, derived from three 
distinct sources. Some important fragments of the typical 
Australian vegetation had reached it across the marine 


498 ISLAND LIFE PART II 


strait, and had spread widely owing to the soil, climate and 
general conditions being exactly suited toit: from the 
north and north-east a tropical vegetation of Polynesian 
type had occupied suitable areas in the north; while the 
extension southward of the Tasmanian peninsula, accom- 
panied, probably, 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 portion 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 Eucalyptus, there 
occur birches, alders, oaks, and beeches ; while in ‘Tasmania 
in freshwater limestone, apparently 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 continental 
extension, and of which the emu, the cassowaries, the 
extinct Dromornis of Queensland, and the moas and kiwis 
of New Zealand, are the modified descendants. 

The Origin of the 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 veriod 


1 «On the Origin of the Fauna and Flora of New Zealand,” by Captain 
F. W. Hutton, in Annals and Mag. of Nat. Hist. Fifth series, p. 427 (June, 
1884), 

2 To these must now be added the genera Sequoia, Myrica, Aralia, and 
Acer, described by Baron von Ettingshausen. (Trans. N.Z. Institute, 
xix., p. 449.) Many botanists, however, doubt the correctness of most 
of these identifications. 


CHAP. XXII THE FLORA OF NEW ZEALAND 499 


i 


when New Zealand was first brought into close connection 
with it, by means of a great north-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, p. 471). The condition of New Zealand previous to 
this event is very obscure. That it had long existed asa 
more or less extensive land is indicated by its ancient sedi- 
mentary rocks; while 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 
had already reached the tropical and sub-tropical portions of 
the astern 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. But 
these apparent anomalies cease to present any difficulty 
when we 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 only 
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, by the fact of the union 
being, not with the temperate, but with the tropical and 
sub-tropical portions of that island, so that only those 
groups could be acquired which were less exclusively 
temperate, and had already established themselves in the 
warmer portion of their new home.! 


1 The large collection of fossil plants from the Tertiary beds of New 
Zealand which have been recently described by Baron von Ettingshausen 
(Trans. N. Z. Inst., vol. xxiii., pp. 237—310), prove that a change in the 
vegetation has occurred similar to that which has taken place in Eastern 
Australia, and that the plants of the two countries once resembled each 
other more than they do now. We have, first, a series of groups now 
living in Australia, but which have become extinct in New Zealand, as 


500 ISLAND LIFE PART II 


It is therefore no matter of surprise, but exactly what we 
should expect, that the great mass of pre-eminently 
temperate Australian genera should be absent from New 
Zealand, including the whole of such important families 
as, Dilleniacee Tremandres, Buettneriace, Polygales, 
Casuarineee and Hzmodoracee; while others, such as 
Rutacee, Stackhousieew, Rhamnez, Myrtaceze, Proteacee, 
and Santalacez, are represented by only a few species. 
Thus, too, we can explain the absence of all the peculiar 
Australian Leguminose ; for these were still mainly 
confined to the great western island, along with the 
peculiar Acacias and Eucalypti, 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 quarter,” 
several should have reached New Zealand, such as Drosera 
some Pittosporeze and Myoporinee, with a few Proteacex, 
Loganiacez, and Restiacez ; for most of these are not only 
found in tropical Australia, but also in the Malayan and 
Pacific islands. 

Troprwal Character of the New Zealand Flora Explained.— 
In this origin of the New Zealand fauna by a north-western 
route from WNorth-eastern Australia, we find also an 
explanation of the remarkable number of tropical groups of 
plants found there : for though, as Sir Joseph Hooker has 
Cassia, Dalbergia, Eucalyptus, Diospyros, Dryandra, Casuarina, and Ficus ; 
and also such northern genera as Acer, Planera, Ulmus, Quercus, Alnus, 
Myrica, and Sequoia. All these latter, except Ulmus and Planera, have 
been found also in the Eastern-Australian Tertiaries, and we may therefore 
consider that at this period the northern temperate element in both floras 
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 types now found there; while the 
Australian portion of the same flora may have succumbed at a somewhat later 
period, when the elevation of the Cretaceous and Tertiary sea united it with 
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. This, however, is strongly contested by many botanists, and 


fuller knowledge is requisite before any trustworthy explanation of the 
phenomena can be arrived at. 


CHAP. XXII THE FLORA OF NEW ZEALAND 501 


shown, a moist and uniform climate favours the extension 
of tropical forms in the temperate zone, yet some means 
must be afforded them for reaching a temperate island. On 
carefully going through the Handbook, and comparing its 
indications with those of Bentham’s Flora Australiensis, I 
find that there are in New Zealand thirty-eight thoroughly 
tropical genera, thirty-three of which are found in 
Australia—mostly in the tropical portion of it, though a few 
are temperate, and these may have reached it through New 
Zealand.1. To these we must add thirty-two more 
genera, which, though chiefly developed in temperate 
Australia, extend into the tropical or sub-tropical portions 
of it, and may well have reached New Zealand by the 
same route. 

On the other hand we find but few New Zealand genera 
certainly derived from Australia which are especially 
temperate, and it may be as well to give a list of such as 


1 The following are the tropical genera common to New Zealand and 
Australia :— 


. Melicope. Queensland, Pacific Islands. 

. Eugenia, Eastern and Tropical Australia, Asia, and America. 

. Passiflora. N.S.W. and Queensland, Tropics of Old World and America. 
Myrsine. Tropical and Temperate Australia, Tropical and Sub-tr opical regions. 
Sapota. Australia, Norfolk Islands, Tropics. 

Cyathodes, Australia and Pacific Islands. 

. Parsonsia. Tropical Australia and Asia. 

. Geniostoma. Queensland, Polynesia, Asia. 

. Mitrasacme. Tropical and Temperate Australia, India. 

10. Ipomea, Tropical Australia, Tropics. 

11. Mazus. Temperate Australia, India, China. 

12. Vitex. Tropical Australia, Tropical and Sub-tropical. 

13. Pisonia. Tropical Australia, Tropical and Sub-tropical. 

14. Alternanthera, Tropical Australia, India, and 8. America. 

15. Tetranthera- Tropical Australia, Tropics. 

16. Santalum. Tropical and Sub-tropical Australia, Pacific, Malay Islands, 

17. Carumbium. Tropical and Sub-tropical Australia, Pacific Islands. 

18. Elatostemma. Sub-tropical Australia, Asia, Pacific Islands. 

19. Peperomia. Tropical and Sub-tropical Australia, Tropics. 

20. Piper. Tropical and Sub-tropical Australia, Tropics. 

21. Dacrydium. Tasmania, Malay, and Pacific Islands. 

22. Dammara. Tropical Australia, Malay, and Pacific Islands. 

23. Dendrobium. Tropical Australia, Eastern Tropics. 

24. Bolbophyllum. Tropical and Sub-tropical Australia, Tropics. 

25. Sarcochilus. Tropical and Sub-tropical Australia, Fiji, and Malay Islands. 
26. Freycinetia. Tropical Australia, Tropical Asia. 

27. Cordyline. Tropical Australia, Pacific Islands. 

28. Dianella. Australia, India, Madagascar, Pacific Islands. 
29. Cyperus. Australia, Tropical regions mainly. 

30. Fimbristylis. Tropical Australia, Tropical regions. 
31. Paspalum. Tropical and Sub-tropical grasses. 

32. Isachne. Tropical and Sub-tropical grasses. 

88. Sporobolus. Tropical and Sub-tropical grasses. 


OWT OUP 9 po ee 


502 ISLAND LIFE PART II 


ne 


do occur with a few remarks. They are sixteen in number, 
as follows :— 


1. Pennantia (1 sp.). This genus has a species in Norfolk Island, indi- 
cating perhaps its former extension to the north-west. 

. Pomaderris (8 sp.). One species inhabits Victoria and New Zealand, 
indicating recent trans-oceanic migration. 

. Quintinia (2 sp.). This genus has winged seeds facilitating migration. 

. Olearia (20 sp.). Seeds with pappus. 

. Craspedia (2 sp.). Seeds with pappus. Alpine; identical with 
Australian species, and therefore of comparatively recent introduc- 
tion. 

6. Celmisia (25 sp.). Seeds with pappus. Only three Australian species, 
two of which are identical with New Zealand forms, probably 
therefore derived from New Zealand. 

7. Ozothamnus (5 sp.). Seeds with pappus. 

8. Epacris (4 sp.). Minute seeds. Some species are sub-tropical, and 
they are all found in the northern (warmer) island of New Zealand. 

9. Archeria (2 sp.). Minute seeds. A species common to E. Australia 
and New Zealand. 

10. Logania (3 sp.). Small seeds. Alpine plants. 

11. Hedycarya (1 sp.). 

12. Chiloglottis (1 sp.). Minute seeds. In Auckland Islands; alpine in 

Australia. 

13. Prasophyllum (1 sp.). Minute seeds. Identical with Australian 

species, indicating 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, 


Or > OO bo 


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. 

Species Common to New Zealand and Australia Mostly 
Temperate Forms.—Let us now take the species 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 


CHAP, XXII THE FLORA OF NEW ZEALAND 503 


—s 


single species which is confined to sub-tropical East 
Australia—a grass (Apera arundinacea) only found ina few 
localities on the New Zealand coast. 

Nowit is clear that the larger portion, if not the whole, 
of these plants must have reached New Zealand from 
Australia (or in a few cases Australia from New Zealand), 
by transmisson across tne sea, because we know there has 
been no actual land connection during late Tertiary times, 
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 600 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 
ereater 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 Colobanthus, Aczna, Gaultheria, 
Pernettya, and Muhlenbeckia, and these may in some cases 
have reached both Australia and New Zealand from some 
now submerged Antarctic island. Again, about one-fourth 
of the whole are alpine plants, and these 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 which, 
having derived the earlier portion of its flora from the side 
of the tropics, would be likely to have its higher mountains 
and favourable alpine stations toa great extent unoccupied, 
or occupied by plants unable to compete with specially 
adapted alpine groups. ; 
LL 


504 | ISLAND LIFE. PART Ii 


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 that these have 
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, wind- fertilised, and are thus independent of any 
peculiar insects, which might be wanting in the new 
country. 

Why Easvly-Dispersed Plants have often Restricted Ranges. 
—This last consideration throws light on a very curious 
point, which has been noted as a difficulty by Sir Joseph 
Hooker, that plants which have most clear and decided 
powers of dispersal by wind or other means, have not 
generally the widest specific range ; and he instances the 
small number of Compositz common to New Zealand and 
Australia. But in all these cases it will, I think, be found 
that although the species have not a wide range the genera 
often have. In New Zealand, for instance, the Composite 
are very abundant, there being no less than 167 species, 
almost all belonging to Australian genera, yet only about 
one-sixteenth of the whole are identical in the two 
countries. The explanation of this 1s not difficult. Owing 
to their great powers of dispersal, the Australian Compositze 
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 


CHAP. XXII THE FLORA OF NEW ZEALAND 505 


with these indigenous and well-established plants, and only 
im a few cases were able to obtain a footing; whence it 
arises that we have many Australian types, but few 
Australian species, in New Zealand, and both phenomena 
are directly traceable to the combination of great powers of 
dispersal with a high degree of adaptability. Exactly the 
same thing occurs with the still more highly specialised 
Orchidez, These are not proportionally so numerous in 
New Zealand (about forty species), and this is no doubt 
due to the fact that so many of them require insect- 
fertilisation often by a particular family or genus (whereas 
almost any insect will fertilise Composite), and insects of 
all orders are rather 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 conditions 
would soon become modified into new species. It 1s thus 
quite intelligible why only three species of orchids are 
identical in Australia and New Zealand, although their 
minute and abundant seeds must be dispersed by the 
wind almost as readily as the spores of ferns. 

Another specialised group—the Scrophularinese— 
abounds in New Zealand, where there are about seventy 
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, and Limo- 
sella, being found in the southern hemisphere. 

Looking at the whole series of these Australo-New 
Zealand plants, we find the most highly specialised 
sroups—Compositz, Scrophularines, Orchidese—with a 
small proportion of identical species (one-thirteenth to one 
twentieth), the less highly specialised—Ranunculacee, 
Onagrariz and Ericee—with a higher proportion (one- 
ninth to one-sixth), and the least specialised—Juncee, 


1 Insects are tolerably abundant in the open mountain regions, but very 
scarce in the forests. Mr. Meyrick says that these are ‘‘ strangely deficient 
in insects, the same species occurring throughout the islands ;” and Mr. 
Pascoe remarked that ‘‘the forests of New Zealand were the most barren 
0," entomologically, he hadever visited.” (Proc, Ent. Soc., 1883. p. 
XX1X, 


506 ISLAND LIFE PART II 


Cyperaceee and Gramineze—with the high proportion in 
each case of one-fourth. These nine are the most 
important New Zealand orders which contain species 
common to that country and Australia and confined to 
them ; and the marked correspondence they show between 
high specialisation and want of specific identity, while the 
generic identity is in all cases approximately equal, points 
to the conclusion that the means of diffusion are, in almost 
all plants ample, when 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. 

Summary and Conclusion on the New Zealand Flora.—Con- 
fining ourselves strictly to the direct relations between the 
plants of New Zealand and of Australia, as I have done in 
the 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- 
gards orders and genera, 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 western and temperate, and New 
Zealand received its immigrants from the eastern island 
which had itself received only a fragment of this flora, and 
from the tropical 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 avery large proportion of tropical forms, for we 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 507 


_ the specially Australian genera in New Zealand are 
largely tropical or sub-tropical, the specially Australian 
species are wholly temperate or alpine; for these are 
comparatively recent arrivals, they must have migrated 
across the sea in the temperate zone, and these temperate 
and alpine forms are exactly such as would be best able to 
establish themselves in a country already stocked mainly 
by tropical forms and their modified descendants. This 
hypothesis further fulfils the conditions implied in Sir 
Joseph Hooker’s anticipation that—‘“ these great differ- 
ences (of the floras) will present the least difficulties to 
whatever theory may explain the whole case,’—for it 
shows that these differences are directly due to the history 
and 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 
prominent Australian genera Acacia, Eucalyptus, Melaleuca, 
Grevillea, &c., have not reached New Zealand in recent 
times along with the other temperate forms that have 
established themselves. But it is doubtful whether any 
detailed explanation of such a negative fact is possible, 
while general explanations sufficient to cover it are not 
wanting. Nothing is more certain than that numerous 
plants never run wild and establish themselves in countries 
_ where they nevertheless grow freely if cultivated ; and the 
explanation of this fact given by Mr. Darwin—that they 
are prevented doing so by the competition of better 
adapted forms—is held to be sufficient. In this particular 
case, however, we have some very remarkable evidence of 
the fact of their non-adaptation. The intercourse between 
New Zealand and Europe has been the means of intro- 
ducing a host of common European plants,—more than 
150 in number, as enumerated at the end of the second 
volume of the Handbook; yet, although the intercourse 
with Australia has probably been greater, only two or 
three Australian plants have similarly established them- 
selves. More remarkable still, Sir Joseph Hooker states: 


508 ISLAND LIFE PART II 


“T am 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 characteristic groups as Acacia 
and Hucalyptus would be among those so scattered, yet we 
have no record of any plants of these or other peculiar 
Australian genera ever having been found wild, still less of 
their having spread and taken possession of the soil in the 
way that many European plants have done. We are, then, 
entitled to conclude that the plants above referred to have 
not established themselves in New Zealand (although 
their seeds may have reached it) because they could not 
successfully 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 


ON THE ARCTIC ELEMENT IN SOUTH TEMPERATE FLORAS 


European Species and Genera of Plants in the Southern Hemisphere— 
Aggressive Power of the Scandinavian Flora—Means by which Plants 
have Migrated from North to South—Newly moved Soil as Affording 
Temporary Stations to Migrating Plants—Elevation and Depression ‘of 
the Snow-line as Aiding the Migration of Plants—Changes of Climate 
Favourable to Migration—The Migration from North to South has been 
long going on—Geological Changes as Aiding Migration—Proofs of 
Migration by way of the Andes—Proofs of Migration by way of the 
Himalayas and Southern Asia—Proofs of Migration by way of the 
African Highlands—Supposed Connection of South Africa and Australia 
—The Endemic Genera of Plants in New Zealand—The Absence of 
Southern Types from the Northern Hemisphere—Concluding Remarks 
on the New Zealand and South Temperate Floras, 


WE have now to deal with another portion of the New 
Zealand flora which presents perhaps equal difficulties— 
that which appears to have been derived from remote parts 
of the north and south temperate zones; and this will lead 
us to inquire into the origin of the northern or Arctic 
element in all the south temperate floras, 

More than one-third of the entire number of New 
Zealand genera (115) are found also in Europe, and even 
fifty-eight species are identical in these remote parts of 
the world. Temperate South America has seventy-four 
genera in common with New Zealand, and there are even 
eleven species identical in the two countries, as well as 
thirty-two which are close allies or representative species, 


510 ISLAND LIFE PART II 


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 Europe and Northern 
Asia, but almost or quite unknown in the warmer regions, 
which yet reappear in temperate Australia. Other genera 
seem altogether Antarctic—that 1s, 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 temperate genera also occur in 
the mountains of South Africa. On the other hand, few if 
any of the peculiar Australian or Antarctic types have 
spread northwards, except some of the former which have 
reached the mountains of Borneo, and a few of the latter 
which spread along the Andes to Mexico. 

On these remarkable facts, of which I have given but 
the barest outline, Sir Joseph Hooker makes the following 
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 from Lapland and Iceland to the tops 
of the Tasmanian Alps, 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 


CHAP. xx11I ARCTIC PLANTS IN NEW ZEALAND 511 


associated with alpine forms of Germanic, Siberian, Oriental, 
Chinese, American, Malayan, and finally Australian, and 
Antarctic types; but whereas these are all, more or less, 
local assemblages, the Scandinavian asserts his prerogative 
of ubiquity from Britain to beyond its antipodes.” } 

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 Joseph 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 he has 
done so much to make known and to elucidate. 

Aggressive Power of the Scandinavian Flora.—tThe first 
important fact bearing upon this question is the wonderful 
ageressive and colonising power of the Scandinavian flora, 
as shown by the way in which it establishes itself in any 
temperate country to which it may gain access. About 150 
species have thus 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. Darwin’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 import- 
ant an agent it must be in the formation of the floras of 
any lands to which these aggressive plants have been able 
to gain access. 

But not only are these plants pre-eminently capable of 
holding their own in any temperate country in the world, 
but they also have exceptional powers of migration and dis- 

1 Introductory Essay On the Flora of Australia, p. 130, 


512 ISLAND LIFE PART II 


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 XIL, 
there is no reason for supposing that they have ever been 
more nearly connected with it than they are now, since an 
extension of the European coast to the 1,000-fathom line 
would very little reduce the distance. Now it is a most 
interesting and suggestive fact that more than half the 
Kuropean 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 through the air, 
carried by storms in the same way as the European birds 
and insects which annually reach the Azores, a few b 
floating on the waters or by a combination of the two 
methods; while some may os 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 the former existence of intermediate islands, 
so often indicated by shoals in the midst of the deepest 
oceans. 

Means by which Plants have migrated from North to 
South.—But if plants can thus pass in considerable numbers 
and variety over wide seas and oceans, it must be yet more 
easy for them to traverse continuous areas of land, where- 
ever mountain-chains offer suitable stations at moderate 


1 Hooker, On the Flora of Australiz, p. 95.—H. C, Watson, in Godman’s 
Azores, pp. 278-286. 


CHAP. XXIII ARCTIC PLANTS IN NEW ZEALAND 513 


intervals on which 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 debris of torrents, and the moraines deposited 
by glaciers, afford numerous unoccupied stations 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 presented by railway cuttings and embankments, 
often produce plants strange to the locality, which survive 
for a few years, and then disappear as the normal vegeta- 
tion gains strength and permanence.! But such a surface 


1 As this is a point of great interest in its bearing on the dispersal of 
plants by means of mountain ranges, I have endeavoured to obtain a few 
illustrative facts :— 

‘1. Mr. William Mitten, of Hurstpierpoint, Sussex, informs me that when 
the London and Brighton railway was in progress in his neighbourhood, 
Melilotus vulgaris made its appearance on the banks, remained for several 
years, and then altogether disappeared. Another case is that of Diplotaxis 
muralis, 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 thick crop of 
a plant locally known as fire-weed—a species of Senecio, probably S. Aus- 
tralis. It never grows except where the fire has gone over the ground, 
and is unknown except in such places. My correspondent adds :—‘‘ This 
autumn I went back about thirty-five miles through a dense forest, along 
a track marked by some prospectors the year before, and in one spot 
where they had camped, and the fire had burnt the fallen logs, &c., there 
was a fine crop of ‘fire-weed.’ All around for many miles was a forest of 
the largest trees and dense scrub.” Here we have a case in which burnt 
soil and ashes favour the germination of a particular plant, whose seeds 
are easily carried by the wind, and it is not difficult to see how this 
peculiarity might favour the dispersal of the species for enormous distances, 
by enabling it temporarily to grow and produce seeds on burnt spots. 

8. In answer to an inquiry on this subject, Mr. H. C. Watson has been 
kind enough to send mea detailed account of the progress of vegetation 
on the railway banks and cuttings about Thames Ditton. This account is 
written from memory, but as Mr. Watson states that he took a great 
interest in watching the process year by year, there can be no reason to 
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 three years, namely, Jsatis 
tinctoria—a species usually supposed to be one of our introduced, but 
pretty well naturalised, plants. The nearest stations then or since known 
to me for this Zsatis are on chalk about Guildford, twenty miles distant. 


514 ISLAND LIFE PART I 


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 /satis on the railway bank near Vauxhall. 

**Close by Ditton Station three species appeared which may be called 
interlopers. The biennial Barbarea precox, one of these, is the least 
remarkable, because it might have come as seed in the earth from some 
garden, or possibly in the Thames gravel (used as ballast). At first it 
increased to several plants, then became less numerous, and will soon, in 
all probability, become extinct, crowded out by other plants. The biennial 
Petroselinum segetum was at first one very luxuriant plant on the slope of 
the embankment. It increased by seed into a dozen or a score, and is now 
nearly if not quite extinct. The third species is Linaria purpurea, 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 has 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 Arabis hirsuta, likely to become a permanent inhabitant. The 
species is found on the chalk and greensand miles away from Thames 
Ditton; but neither in this parish nor in any adjacent parish, so far as 
known to myself or to the authors of the flora of the county, does it 
occur. Some years after the railway was made a single root of this 
Arabis was observed in the brickwork of an arch by 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. 
Now 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 ? 

‘The Bee Orchis (Ophrys apifera), 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 see 
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. JI 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 Norfolk, 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 Cnothera odorata 


CHAP. xx11II ARCTIC PLANTS IN NEW ZEALAND 515 


where, the general conditions being more favourable, it 
was able to establish itself as a permanent member 
of the flora. Such, generally speaking, was probably the 
process by which the Scandinavian flora has made its way 
to the southern hemisphere ; but it could hardly have done 
so to any important extent without the aid of those 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 south 
across the whole width of the tropics referred to by Sir 
Joseph Hooker. Those causes were, the repeated changes 


and Delphiniwm Ajacis (the latter only known thirty miles off in corn- 
fields in Cambridgeshire), with Atriplex patula and A. deltoidea. Gradually 
the native sand plants—Carices, Grasses, Galiwm verwm, &c., established 
themselves, and year by year covered more ground till the new introduc- 
tions almost completely disappeared. The same phenomenon was observed 
in Cambridgeshire between Chesterton and Newmarket, where, the soil 
being different, SteZlaria 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 Stellaria was to be seen. 

5. Mr. T. Kirk (writing in 1878) states that—‘‘in Auckland, where a 
dense sward of grass is soon formed, single specimens of the European milk 
Thistle (Cardwus marianus\ have been known for the 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 up and flowered. The railway works 
being suspended, the plant increased rapidly, and spread wherever it could 
find disturbed soil.” 

Again :—‘‘ The fiddle-dock (Rumex pulcher) occurs in great abundance 
on the formation of new streets, &c., but soon becomes comparatively rare. 
It seems probable that it was one of the earliest plants naturalised here, 
but that it partially died out, its buried seeds retaining their vitality.” 

Medicago sativa and Apium graveolens, are also noted as escapes from 
cultivation which maintain themselves for a time but soon die out. 

The preceding examples of the temporary establishment of plants on 
newly exposed soil, often at considerable distances from the localities they 
usually inhabit, might, no doubt, by further inquiry be greatly multiplied ; 
but, unfortunately, the phenomenon has received little attention, and is 
not even referred to in the elaborate work of De Candolle (Géographie 
Botanique Raisonnée) in which almost every other aspect of the dispersion 
and distribution of plants is fully discussed. Enough has been advanced, 
however, to show that it is of constant occurrence, and from the point of 
view here advocated it becomes of great importance in explaining the 
almost world-wide distribution of many common plants of the north 
temperate zone. 


1 Transactions of the New Zealand Institute, Vol. X. p. 367. 


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. 

Elevation and Depression of the Snow Lnne as Aiding the 
Migration of Plants—We have endeavoured to show (in an 
earlier portion of this volume) that wherever geographical 
or physical 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 excentricity. But along 
with such depression of the line of perpetual 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 would 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 
ebove 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-slips, berg-falls, and floods, with their 


CHAP. xx11I ARCTIC PLANTS IN NEW ZEALAND 517 


accompanying accumulations of débris and of alluvial soil, 
affording innumerable stations in which solitary wind- 
borne seeds might germinate and temporarily establish 
themselves. 

This lowering and rising of the snow-line each 10,500 
years during periods of high excentricity, would occur in 
the northern and southern hemispheres alternately ; and 
where there were high mountains within the tropics the 
two would probably overlap each other, so that the 
northern depression would make itself felt in a slight 
degree even across the equator some way into the southern 
hemisphere, and vice versd ; and even if the difference of 
the height of perpetual snow at the two extremes did not 
average more than a few hundred feet, this would be 
amply sufficient to supply the new and unoccupied 
stations needful to facilitate the migration of plants. It 
is well known that all great mountain ranges have 
undergone such fluctuations, as proved by ice-marks below 
the present level of snow and ice. 

But the differences of temperature in the two hemi- 
spheres caused by the sun being in perthelion in the 
winter of the one while it was in aphelion during the same 
season in the other, would necessarily lead to increased 
aérial and marine currents, as already explained; and 
whenever geographical conditions were such as to favour 
the production of glaciation in any area these effects would 
become more powerful, and would further aid in the 
dispersal of the seeds of plants. 

Changes of Clumate Favourable to Migration.—It is clear 
then, that during periods when no glacial epochs were 
produced in the northern hemisphere, and even when a 
mild climate extended over the whole polar area, alternate 
changes of climate 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 high 
excentricity which produced an extensive glaciation in 
the northern hemisphere and local glaciations in the 
southern, these risings and lowerings of the snow-line on 
all mountain ranges would have been at a maximum, and 


MM 


518 ISLAND LIFE PART IT 


would have been increased by the depression of the ocean 
which must have arisen from such a vast bulk of water 
being locked up in land-ice, and which depression would 
have produced the same effect as a general elevation of all 
the continents. At this time, too, aérial 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 plumage or 
in the stomachs of birds, smce 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 
Proteacez 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 
Hiring (? Belgium)! Then we have such peculiar genera 


1 Sir Joseph Hooker informs me that he considers these identifications 
worthless, and Mr. Bentham has also written very strongly against the 
value of similar identifications by Heer and Unger. Giving due weight to 
the opinions of these eminent botanists we must admit that Australian 
genera have not yet been demonstrated to have existed in 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 plants which have been noticed by 


CHAP, xx11I ARCTIC PLANTS IN NEW ZEALAND 519 


as Pachychladon and Notothlaspi of New Zealand said to 
have affinities with Arctic plants, while Stilbocarpa— 
another peculiar New Zealand genus—has its nearest 
allies in the Himalayan and Chinese 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 
Kuropean 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 
alternattons of warmer and colder climates in either 
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 of 


different observers should adi be illusory ; while the well established fact 
of the former wide distribution of many tropical or now restricted types of 
plants and animals, so frequently illustrated in the present volume, removes 
the antecedent improbability which is supposed to attach to such identifi- 
cations. I am myself the more inclined to accept them, because, according 
to the views here advocated, such migrations must have taken place at 
remote as well as at recent epochs ; and the preservation of some of these 
types 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 elsewhere in this volume, 
and also repeatedly in my larger work. 

MM 2 


520 ISLAND LIFE PART II 


the plants of the Miocene period of Europe were so much 
like existing species 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-aérial 
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 with an example of 
a continent of vast antiquity, we may be sure that its 
great central plateaux once bore far loftier mountain 
ranges before they were reduced to their present oni 
by long ages of denudation. 

Proofs of Migration by Way of the Andes. ee are now 
prepared to apply 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 im 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 1s to be found in the 
American continent, the only break of importance being 
the comparatively low Isthmus of Panama, where there is 


1 Out of forty-two genera from the Eocene of Sheppey enumerated 
by Dr. Ettingshausen in the Geological Magazine for January 1880, only 
_two or three appear to be extinct, while there is a most extraordinary inter- 
mixture of tropical and temperate forms—Musa, Nipa, and Victoria, with 
Corylus, Prunus, Acer, &c. The rich Miocene flora of Switzerland, 
described by Professor Heer, presents a still larger proportion of living 
genera. 


CHAP. xx1II ARCTIC PLANTS IN NEW ZEALAND 521 


a distance 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 to the 
diffusion of plants; and we should accordingly expect that 
this great continuous mountain-chain has formed the most 
effective agent in aiding the southward migration of the 
Arctic and north temperate vegetation. We do find, in 
fact, not only that a large number of northern genera and 
‘many species are 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 Kurope 
and the Arctic regions. Considering how comparatively 
little the mountains of South Temperate America are yet 
known, this is a very remarkable result, and it proves 
that the transmission of species must have gone on up to 
comparatively recent times. Yet, as only a few of these 
Species are now found along the line of migration, we see 
that they only occupied such stations temporarily ; and we 
-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 
exposed them to the competition of indigenous plants from 
the belt of country immediately below them. 

Now, just as these numerous species and genera have 
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 Horn, at a 
distance of only 500 miles, are the South Shetland Islands 
and Graham’s Land, whence the Antarctic continent or a 


522 ISLAND LIFE PART II 


—————_ = 


group of large islands probably extends across or around the 
south polar area to Victoria Land and thence to Adélie 
Land. The outlying Young Island, 12,000 feet high, is 
about 750 miles south of the Macquarie Islands, which 
may be considered a southern outler 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 we know are 
traversed by plants both by flotation and by aérial currents, 
especially in such a stormy atmosphere as that of the 
Antarctic regions. Now, we may further assume, that 
what we know occurred within 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 steady 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 which 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 


1 The recent discovery by Lieutenant Jensen of arich 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. (See Nature, Vol. XXI. p. 345.) 


CHAP. xx11I ARCTIC PLANTS IN NEW ZEALAND 523 


repeated several times during the Tertiary period, we have 
no difficulty im understanding the general community 
between the European and Antarctic plants found in all 
south temperate lands. Kerguelen’s Land and The Crozets 
are within about the same distance from the Antarctic 
continent as New Zealand and Tasmania, and we need not 
therefore be surprised at finding in each 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 Hooker 
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 these 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 Migration by way of the Himalayas 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, we cannot account for 
the whole of it by this means, because Australia itself con- 
tains a host of European and Asiatic genera of which we 
find no trace in New Zealand or South America, or any 
other Antarctic land. We find, in fact, in Australia two 
distinct sets of European plants. First we have a number 
of species identical with those of Northern Europe or Asia 
(of the most characteristic of which—thirty-eight in 
number—Sir Joseph Hooker gives a list) ; and in the sec- 
ond place a series of European genera usually of a some- 
what more southern character, mostly represented by 
very distinct species, and all absent from New Zealand ; 
such as Clematis, Papaver, Cleome, Polygala, Lavatera, 
Ajuga, &c. Now of the first set—the North European 
species—about three-fourths occur 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-European genera, 
however, and many others characteristic of the South EKuro- 
pean or the Himalayan flora, have probably reached 
Australia by way of the mountains of Southern Asia, 
Borneo, the Moluccas, and New Guinea, at a somewhat 
remote period when loftier ranges and some intermediate 
peaks may have 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 
Palzozoic 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 Migration by way of the African Highlands— 
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 representation 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 IN NEW ZEALAND 525 


is clear, therefore, that South Africa has received its Euro- 
pean plants by the direct route through the Abyssinian 
highlands and the ‘lofty equatorial mountains, and mostly 
at a distant period when the conditions for migration were 
somewhat more favourable than they are now. The much 
greater directness of the route from Northern Europe to 
South Africa than to Australia; and the existence even 
now of lofty mountains and extensive highlands for a large 
portion of the distance, will explain (what Sir Joseph 
Hooker notes as “a very curious fact”) why South Africa 
has more very northern European genera than Australia, 
while Australia has more identical species and a better rep- 
resentation on the whole 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 flora above 
referred to. 

Supposed Connection of South Africa and Australia.— 
There remains, however, the small amount of direct affinity 
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 which 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 differences 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 except 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 that have taken place 


526 ISLAND LIFE PART II 


in the distribution of all forms of life. Just as we explain 
the presence of marsupials in Australia and America and 
of Centetidee in Madagascar and the Antilles, by the pre- 
servation in these localities of remnants of once wide-spread 
types, so we should prefer 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 Restiaceee—or of world-wide distribution, as 
Melanthacee. 

The Endemic Genera of Plants in New 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 Leguminose, Saxifragee, 
Composite, Orchideze, &. We 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 
Paleozamia, Oleandrium, Alethopteris, Camptopteris, Cycadites, Echino- 
strobus, &c., all Indian forms of the same age. Neocomian beds contain 
a true dicotyledonous leaf with Dammara and Araucaria, 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 North Temperate genera which 
have since become extinct. (See p. 499, footnote, and 7’rans. New Zealand 


Inst., Vol. XI. 1879, p. 536.) 


CHAP. xx1II ARCTIC PLANTS IN NEW ZEALAND 527 


the influence of changed conditions, which are manifested 
by the extreme peculiarity of many of these interesting 
endemic forms. 

The Absence of Southern Types from the Northern Hemi- 
sphere.—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 the 
Antarctic lands, New Zealand, South America, or South 
Africa. The furthest northern outliers of the southern 
flora are a few genera of Antarctic type on the Bornean 
Alps; the genus Aczena which has a species in California ; 
two representatives of the Australian flora—Casuarina 
and Stylidium, in the peninsula of India; while China 
and the Philippines have two strictly Australian genera of 
Orchideze—Microtis and Thelymitra, as well as a Resti- 
aceous genus. Several distinct causes appear to have 
combined to produce this curious inability of the southern 
flora to make its way 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, 
we 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—South Tem- 
perate America, South Africa, and Australia—are widely 
separated from each other, and have in all probability 
always been so; whereas the whole of the north temperate 
lands are practically continuous. It follows that, instead of 
the enormous northern area, in which 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 with special adapta- 


528 ISLAND LIFE PART II 


tions to soil, climate, and organic environment, but 
comparatively impotent and inferior beyond their own 
domain. 

Another circumstance which makes the contest between 
the northern and southern forms still more unequal, is the 
much greater hardiness of the former, from having been 
developed in a colder region, and one where alpine and 
arctic conditions 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 grow and flourish even more vigorously than in their 
native land, the southern plants would find in almost 
every part of Kurope, 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.! 

1 The fact stated in the last edition of the Origin of Species (p. 340) on 
the authority of Sir Joseph Hooker, that Australian plants are rapidly 
sowing themselves and becoming 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 favour- 
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 chance 
of success. 


CHAP. xx11I ARCTIC PLANTS IN NEW ZEALAND 529 


Concluding Remarks on the Last Two Chapters——Our 
inquiry into the external relations and probable origin of 
the fauna and flora of New Zealand, has thus led us on to 
a general theory as to the cause of the peculiar biological 
relations between the northern and the southern 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 which has here been given of one of the 
most difficult of this class of problems, has been rendered 
possible solely by the knowledge very recently obtained 
of the form of the sea-bottom in the southern ocean, and 
of the geological 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 Kast from West Australia during a portion of* 
the Cretaceous and Tertiary periods, could never have been 
cuessed till it was established by the laborious explorations 
of the Australian geologists ;+ while the hypothesis of a 
comparatively shallow sea, uniting New Zealand by a long 
route with tropical Australia, while a profoundly deep 
ocean always separated it from 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 


1 Mr. Spencer Moore (in his articles on the “‘ Origin of the Australian 
Flora” in Natural Science, Sept. and Oct. 1899) denies this, on the 
ground that Tertiary deposits are not known to extend far inland. But 
according to the best geological map of Australia (see Stanford’s Com- 
pendium, Vol. I, p. 83), Tertiary formations surround the mountains of 
Central Australia for six hundred miles from north to south, and, with 
but moderate intervening Cretaceous areas (from above which they may 
well have been removed by denudation as the chalk, and the eocene 
from above the chalk, have been removed from above the wealden formation 
in the South of England) distinctly indicate an extensive submersion such 
as I suggest. Mr. Moore speaks of ‘‘ the palpable errors” of my views as 
here expressed, but I cannot find that he has specified them; and I may 
now state, that, after again carefully reading his articles, I can find no 
reason for modifying either the facts or the reasoning of the explanation 
here given. 


530 ISLAND LIFE PART II 


in the flora of Australia and its relation to that of New 
Zealand. 

In the more general explanation of 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 great 
amount, given in Chapters VIII. and [X. ; while the whole 
discussion justifies the importance attached to the theory 
of the general permanence of continents and oceans, as 
demonstrated in Chapter VI., since any rational explana- 
tion based upon facts (as opposed to mere unsupported 
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 
affords a firm 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 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 Mr. Croll— 
Supposed Limitations of Geological Time—Time Amply Sufficient both 
for Geological and Biological Development—Insular Faunas and Floras 
—The North Atlantic Islands—The Galapagos—St. Helena and the 
Sandwich Islands—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, 


THE present volume has gone over a very wide field both 
of facts and theories, and it will be well to recall these to 
the 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 the development of a 
clear and definite theory, and its application to the solution 
of a number of biological problems. That theory is, 
briefly, that the distribution of the various species and 
groups of living things over the earth’s surface, and their 
ageregation in definite assemblages in certain areas, is the 


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 of development 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 physical origin, in three groups or classes, each 


SS 


CHAP. XXIV SUMMARY AND CONCLUSION 533 


of which are shown to exhibit certain well-marked biological 
features. 

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 several, chapters, by 
means of which this general conception has been carried 


out. 

Beginning with simple and familiar facts relating to 
British and European quadrupeds and birds, I have 
defined and shown the exact character of ‘areas of 
distribution,” as applied to 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, growth, and decay of 
species and genera are traced, and all the 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 which 
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 barriers 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 1t 1s 
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 grand 


features of our globe—the position of the great oceans 
NN 


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, which is so often said to be the exact 
equivalent of the “globigerina ooze” now forming in 
mid-Atlantic, is shown to be a comparatively shallow- 
water deposit formed in inland seas, or in the immediate 
vicinity of land. The general stability of continents has, 
however, been 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 produced the equally well demonstrated mild 
climate in the Arctic regions, we shall. be quite 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 adopting generally 
Mr. Croll’s views 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 AND CONCLUSION 535 


shown, by a variety of evidence, that without high land 
there can be no permanent snow and ice. From these 
facts and principles the very important conclusion is 
reached, that the alternate phases of precession—causing 
the winter of each hemisphere to be in aphelion and 
perrhelion each 10,500 years—would produce a complete 
change of climate only where a country was partially 
snow-clad ; while, whenever a large area became almost 
wholly 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 when 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 the geological 
evidence as to interglacial mild periods. 

Discussing next the evidence for glacial epochs in 
earlier times, it 1s 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 Aretic 
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 amply accounted for, With such 
favourable geographical conditions, it is shown, that 
changes of excentricity and of the phases of precession 
would have no other effect than to cause greater differences 


NN? 


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 explained 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 geographical 
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 favour the 
transfer of warm oceanic currents to the north far in 
excess of those which move towards the south, and 
whenever these currents had free passage through the 
northern land-masses to the polar area, a mild climate 
must have prevailed over the whole northern hemisphere. 
It is only in very recent times that the great northern 
continents have become so completely consolidated as 
they now are, thus shutting out the warm water from 
their interiors, and rendering possible a wide-spread and 
intense glacial epoch. But this great climatal change was 
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 produced 
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 


CHAP. XXIV SUMMARY AND CONCLUSION 537 


and the Himalayas, in Eastern North America and west 
of the Rocky Mountains, in the Andes of South Temperate 
America, in Tasmania, and in New Zealand, huge 
moraines and other unmistakable ice-marks attest the 
universal descent of the snow-line for several thousand 
_ feet below its present level. If we reject the influence of 
high excentricity as the cause of this almost universal 
glaciation, we must postulate a general elevation of all 
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 
destroying agent, forbid the idea that they belong to 
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 strie, 
undisturbed and uneffaced on the slopes and in the 
valleys of these same mountains. 

The theory of geological climates set forth in this 
volume, while founded on Mr. Croll’s researches, differs 
from all that have yet been made public, in clearly 
tracing out the comparative influence of geographical and 
astronomical revolutions, showing that, while the former 
have been the chief, if not the exclusive, causes of the 
long-continued mild climates of the 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 in low latitudes, of which 
there is such an abundance of evidence. 

The next question discussed is that of geological 
time as bearing on the development ofthe organic world. 
The periods of time usually demanded by geologists have 
been very great, and it was often assumed that there was 
no occasion to limit them. But the theory of development 
demands far more; for the earliest fossiliferous rocks 


538 ISLAND LIFE PART II 


prove the existence of many and varied forms of life which 
require unrecorded ages for their development—ages 
probably far longer than those which have elapsed from 
that period to the present day. The physicists, however, 
deny that any such indefinitely long periods are 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 change 
and organic development. It is therefore important to 
inquire whether these processes are either of them so 
excessively slow as has been supposed, and I devote a 
chapter to the 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 
maximum thickness of the known 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 avea 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. Ihave 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.as data, the 


CHAP. XXIV SUMMARY AND CONCLUSION 539 


proportionate change of the species of mollusca affords 
a means of arriving at the whole lapse of time represented 
by the fossiliferous rocks ; and these two estimates agree 
in the order of their magnitudes. 

It is then argued that the changes of climate every 
10,500 years during the numerous periods of high 
excentricity have acted as a motive power in hastening on 
both geological and biological change. By raising and 
lowering the snow-line in all mountain ranges it has 
caused increased denudation ; while the same changes 
have caused much migration and disturbance in the organic 
world, and have thus tended to the more rapid modification 
of species. The present epoch being a period of very low 
excentricity, the earth is in a phase of exceptional stability 
' 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 anomalies 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, both 
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 whose 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 simplest 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, 
we show why it is comparatively poor in species and why 
this poverty is still greater in Ireland. By a careful 
examination of its fauna and florait 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 which 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- 


Ss —_ @ 


CHAP. XXIV SUMMARY AND CONCLUSION 541 


nary studies we have made enable us to afford a simpler 
and more definite interpretation of the peculiar relations 
of Java to the continent and its differences from Borneo 
and Sumatra, than was given in my former work (The 
Geographical Distribution of Animals). 

Japan and Formosa are next taken, as examples of 
islands which are decidedly somewhat more ancient than 
those 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—as 
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 1s shown are 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 paleeontological facts. 

There remain two other islands—Celebes and New 
Zealand—which are classed as “ anomalous,” the one because 
it is almost impossible to place it in any of the six 
zoological regions, or determine whether it has ever been 
actually joined to a continent—the other because it 


542 ISLAND LIFE PART II 


combines some of 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 principles laid down in our First 
Part, lead to a solution of the problem at once more simple 
and more satisfactory than any which have been previously 
proposed. I now look upon Celebes as an 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 characters of some of them remain as mysterious 
as ever, 

New Zealand is shown to be so completely continental in 
its geological structure, and its numerous wingless birds so 
clearly imply a former connection with some other land 
(as do its numerous lizards and its remarkable reptile, 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 by Captain Cook. 
The more accurate knowledge which has recently been 
obtained of the sea bottom around New Zealand enables 
us to determine that the former connection of that island 
with Australia was towards the north, and this is found 
to agree well with many of the peculiarities of its 
fauna. 

The flora of New Zealand and that of Australia are 
now both so well known, and they present so many 
peculiarities, and relations of so anomalous a character, 


CHAP, XXIV SUMMARY AND CONCLUSION 548 


as to present in Sir Joseph Hooker’s opinion an almost 
insoluble problem. Much additional information on the 
physical and geological history of these two countries has, 
however, been obtained since the appearance of Sir Joseph 
Hooker's works, and I therefore determined to apply to 
them the same method of discussion and treatment which 
has been usually successful with similar problems in the 
case of animals. The fact above noted, that New Zealand 
was connected with Australia in its northern and tropical 
portion only, of itself affords a clue to one portion of the 
specialities of the New Zealand flora—the presence 
of an unusual number of tropical families and genera, 
while the temperate forms consist mainly of species either 
identical with those found in Australia or closely allied to 
them. But a still more important 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 highly peculiar 
flora of temperate Australia was developed. This is found 
to explain with great exactness the remarkable absence 
from New Zealand of all the most abundant and 
characteristic Australian genera, both of plants and of 
animals, since these existed at that time only in the 
western island, while New Zealand was in connection with 
the eastern 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 wider, and if possible 
more interesting subject—the origin of the European 
element in the floras of New Zealand and Australia, and 
also in those of South America and South Africa. This is 
so especially a botanical question, that it was with some 
diffidence I entered upon it, yet it arose so naturally from 
the study of the New Zealand and Australian floras, and 
seemed to have so much light thrown 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 ‘PART II 


it. The subject will be so fresh in the reader’s mind that 
a complete summary of it is unnecessary. I venture to 
think, however, that I have shown, not only the several 
routes by which the northern plants have reached the 
various southern lands, but have pointed out the special aids 
to their migration, and the motive power which has urged 
them on. 

In this discussion, if nowhere else, will be found a 
complete justification of that lengthy investigation of the 
exact nature of past changes of climate, which to some 
readers may have seemed unnecessary and unsuited to 
such a work as the present. 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 wide 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 
complete interdependence of organic and morganic nature. 
Not only does the marvellous structure of each organised 
being involve the whole past 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 which cause a periodic variation 
of terrestrial climates—on the apparently 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 various causes 
are far too complex in their combined action to enable us 
to follow them out in the case of any one species, yet 
their broad results are clearly recognisable ; and we are 
thus encouraged to study more completely every detail and 


me: ort tae ‘te — 


“AND Sais | 


aly yj in aed distdibution of living ines in ‘the 
ction that by so doing we shall obtain a fuller 
rer insight into the course of nature, and with 
ed Fetence that the “mighty maze’ ’ of Being we sg 
ary ywhere around us is “not without a plan.” iv 


} 
. 
] 
A : 
' e 
« 
J 
4 ‘ 
cf * 
7 
- iM Lg 
) Ru yy are f 
f Ries -o wt, 
Fe *. ta Sa wali “SY ay) ee af > 
11” inn Te oT CMS ALE  eiaeh dae hey 9 Se 
2 yang i Laeeg Ha ae a a aihlt Ay Ps Bet 


INDEX 


A. 


Acacia, wide range of in Australia, 185 
Acacia heterophylla, and Acacia koa, 443 
Acezena in California, 527 
Accipiter hawaii, 314 
Achatinelline, average range of, 317 
figialitis sanctee-helene, 305 
Africa, characteristic mammalia of, 416 
former isolation of, 418 
Africa and Madagascar, relations of, 418 
early history of, 419 
African highlands as aiding the migra- 
tion 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 
Alectorenas pulcherrimus, 430 
lien, Mr. J. A., on variation, 58 
lied species occupy separate areas, 478 
Alpine plants, their advantages as colo- 
nisers, 503 
Alternations of climate in Switzerland 
and North America, 121 
Alternations of climate, paleontological 
evidence of, 119 
Amazon, limitation of species by, 18 
Amblyrhynchus cristatus, 279 
American genera of reptiles in Mada- 
gascar, 418 
Amphibia, dispersal of, 76 
of the Seychelles, 430 
introduced, of Mauritius, 435 
of New Zealand, 483 
Amphioxus, 63 
Amphisbeenidez, 28 
Amydrus Tristramii, restricted range of, 
16 
Anas Wyvilliana, 314 
Ancient continental islands, 244, 411 
Ancient glacial epochs, 169 
what evidence of may be expected, 
175 
Ancient groups in Madagascar, 419 
Andersson, N. J., on the flora of the 
a. Galapagos, 288 


Andes, migration of plants along the, 520 
Angrecum sesquipedale, 440 
Animal cs effects of glacial epoch on, 
11 
Animal life of Formosa, 401 
Anoa depressi ornis, 455a 
Antarctic continent as a means of plant- 
dispersion, 521 : 
Antarctic islands, with perpetual snow, 
136 
Antelopes, overlapping genera of, 29 
Antiquity of Hawaiian fauna and flora, 
328 
of land-shells, 79 
of New Zealand, 526 
of plants as affecting their dispersal, 
82 


Apera arundinacea, 503 

Apium graveolens 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 hemisphere, 


509 
Arctic regions, mild climates of, 181 
recent interglacial mild period in, 182 
Arctic warm climates of Secondary and 
Paleozoic times, 201 
Areas of distribution, 13 
separate and overlapping, 17, 28 
Ascension, former climate and produc- 
tions of, 303 
Astronomical and geographical causes, 
comparative effects of, on climate, 
207 
Astronomical causes of change of climate 


126 
of glaciation, 140 
Atlantic isles, peculiar mosses of, 368 
Atlantosaurus, the largest land-animal, 


Atriplex patula on a railway bank, 515 
Auchenia, 27 


_Austen, Mr. Godwin, on littoral shells in 


deep water, 337 
O00 


550 


INDEX 


Australia, two sets of Northern plants 
in, 523 
South European plants in, 523 
Australia and South Africa, supposed 
connection of, 525 
Australian Alps, indications of glaciation 
in, 163 
birds 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 
orchidez 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 
_Aylward, 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, 253 
beetles of, 253 
land-shells of, 256 
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. 
Babirusa alfurus in Celebes, 455a, 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 
Barbar a precox on railway bank, 514 
Barn-owl, wide range of, 15 
«Baron, Rev. R., on the flora of Mada- 
gascar, 441 
Barriers to dispersal, 73 
Batrachia, 30 
Bats in Bermuda, 269 
Bears of Europe and America. 


Beaver of Europe and America, 14 
_Beeby, Mr. W. H., on new plants in the 
Shetland Is., 370 
Beetles of the Azores, 253 
remote affinities of some of, 255 
of the Galapagos, 284 
of St. Helena, 298 
of the Sandwich Islands, 318 
Beetles, peculiar British species of, 349 
Bell-birds, distribution of, 24 
.Bennett, Mr. Arthur, on peculiar British 
plants, 361 
ly is vegetation of railway banks, 


.Bentham, Mr., on the composite of the 
Galapagos, 288 
on the compositz of St. Helena, 307 
on the Mascarene compositz, 445 
on Sandwich Island composite, 325 
Bermuda, 262 
soundings around, 263 
red clay of, 265 
zoology of, 266 
reptiles of, 266 
birds of, 266 
insects of, 269 
land-mollusca of, 270 
flora of, 271 
Bermuda and Azores, comparison of 
bird-faunas of, 268 
Bernicla sandvichensis, 314 
Biological causes which determine dis- 
tribution, 532 
Biological features of Madagascar, 416 
Birds as plant-dispersers, 81 
as seed-carriers, 81, 258 
common 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, 378 
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 islands, 436 
of islands east and west of Celebes, 
454 
of Celebes, 457 
peculiar to Celebes, 458 


INDEX bod 


Birds, Himalayan types of, in Celebes, 
462 


list of, land-birds of Celebes, 465 
of New Zealand, 476, 482 
wingless, of New Zealand, 476 
_Blackburn, Mr. T., on the beetles of the 
Sandwich Islands, 317a 
..Blakiston and Pryer on birds of Japan, 
396 


_Bilanford, Mr. W. T., on small effect of 
marine denudation, 225 
..Blanford, Mr. H. F., on former connec- 
tion of Africa and India, 426 
Blocks, travelled and perched, 109 
Blue magpies, range of, 15 
Borneo, geology of, 375 
mammalia of, 376 
birds of, 378 
affinities of fauna of, 380 
Borneo and Asia, resemblance of, 6 
Borneo and Java, 373 
Boulder-beds of the carboniferous forma- 
tion, 201 
Boulder clays of East of England, 118 
Bovidee, 29 
_Brady, Mr. H. B., on habitat of globi- 
gerine, 92 
_Braithwaite, Dr. R., on peculiar British 
mosses, 365 
Britain, probable climate of, with winter 
in a helion, 156 
British birds, range of, 34-38 
British Columbia, interglacial warm 
periods in, 121 
ee 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, 346a 
peculiar Coleoptera of, 351 
peculiar Trichoptera of, 355 
peculiar land and fresh-water shells 
of, 354 
peculiarities of the flora of, 360 
peculiar mosses and Hepatic of, 366 
British mammals as indicating a zoologi- 
cal region, 33 
_Buller, 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, 346a. 


C. 


Caddis-flies peculiar to Britain, 355 
Cecilia, species of in the Seychelles, 432 
wide distribution of, 432 


Ceeciliadze, 28 

Callithea Leprieuri, distribution of, 18 

Callithea sapphira, 18 

Camels as destroyers of vegetation, 296 
former wide distribution of, 420 

Camelus, 17, 27 

Campanula vidalii, 261 

Canis, 17, 26 

Carabus, numerous species of, 42 

Carboniferous boulder-beds, 2U1 
warm Arctic climate, 201 

Carnivora in Madagascar, 417 


Carpenter, Dr., on habitat of globigerinz, 
92 
_Carpenter, Mr. Edward, on Mars and 


glacial periods, 164 
Carduus marianus in New Zealand, 515 
Carpodacus purpureus and P. californicus, 
68 


Castor, 17 

Casuarina, 185 
in India, 527 

Cause of extinction, 63 

Caves of Glamorganshire, 336 

Cebibz, overlapping genera of, 29 

Celebes, physical features of, 451 
map of islands around, 452 
zoology of, 455 
derivation of mammals of, 456 
birds of, 457 
not a continental island, 461 
insect peculiarities of, 462 
Himalayan types in, 462 
peculiarity of butterflies of, 463 
list of land-birds of, 465 

Centetideze, 27 

Centetide, 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 
water, 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, erro- 
neous, 96 
‘‘Challenger” soundings and _ shore-de- 
posits, 86 
“Challenger” ridge in the Atlantic, 101 
Chameleons very abundant in Mada- 
gascar, 430 
Chamois, distribution of, 13 
Changes of land and sea, 83 
Chasmorhynchus, distribution of, 24 
C. nudicollis, 24 
C. tricarunculatus, 24 
C. variegatus, 24 
C. niveus, 24 
Chilomenus lunata, 300 
Chinchillas, 26 
002 


552 


INDEX 


Chrysochloridz, 29 
Cicindela, 17 
Cicindelidze common to South America 
and Madagascar, 28 
Clarke, Mr. W. Eagle, on Philippine 
mammalia, 386 
on Philippine birds, 388 
Clay, red, of Bermuda, 265 
Climate, astronomical causes of changes 
of,. 126 
Climate, properties of snow and ice in 
relation to, 131 
of Britain with winter in aphelion, 
156 
of Tertiary period in Europe and 
N. America, 178 
temperate in Arctic regions, 181 
causes of mild Arctic, 190 
of Tertiary and Secondary periods, 
199, 202 
of the Secondary and Paleozoic 
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, 354 
Cold alone does not cause glaciation, 135 
how it can be stored up, 133 
Coleoptera of the Azores, 253 
of St. Helena, 298 
of the Sandwich Islands, 318 
peculiar British species of, 349 
Comoro Islands, 428 
mammals and birds of, 428 
Compositee of the Galapagos, 288 
of St. Helena, 307 
of the Sandwich Islands, 325 
of the Mascarene Islands, 445 
species often have restricted ranges, 
504 
Conclusions on the New Zealand flora, 
506 
Contemporaneous formation of Lower 
Greensand and Wealden, 221 
zontinental conditions throughout geo- 
logical time, 97-99 
changes and animal distribution, 102 
extensions will not explain anoma- 
lous facts of distribution, 449 


Continental islands, 243 
of recent origin, 331 
general remarks on recent, 408 
ancient, 411 
Continental period, date of, 337 
Continents, movements of, 88 
permanence of, 97 
general stability of, 101, 103 
geological development of, 205 
Continuity of land, 74 
oS of now isolated groups, proof 
of, 70 
Cook, Captain, on a native quadruped in 
New Zealand, 476 
_Cope, oP ies os on the Bermuda lizard, 


Coracias temminckii, in Celebes, 462 
Corvus, 17 
Cossonide, in St. Helena, 299 
Cretaceous deposits in North Australia, 
493, 496 
Cretaceous flora of Greenland, 185 
of the United States, 189 
_Croll, — James, on Antarctic icebergs, 
36 
on winter temperature of Britain in 
glacial epoch, 141 
on diversion of gulf-stream during 
the glacial epoch, 143 
on loss of heat by clouds and fogs, 
145 
on geographical causes as affecting 
climate, 148 
on ancient glacial epochs, 170 
on universality of glacial markings 
in Scotland, 174 
on mild climates of Arctic regions, 
189 
on ocean-currents, 190, 204 
on age of the earth, 213 
on mean thickness of sedimentary 
rocks, 220 
on small amount of marine denuda- 
tion, 225 
on buried river-channels, 336 
Ctenodus, 69 
Cyanopica, distribution of, 24 
Cyanopica cooki, restricted range of, 15, 
24 


Cyanopica cyanus, 24 
Cynopithecus niger, in Celebes, 455a 


D. 


Dacelo, 47 
_.Dana on continental upheavals, 88 
~ on chalk in the Sandwich Islands, 30 
on elevation of land causing the 
glacial epoch, 152 
on elevation of Western America 
194 
on the development of continents 
205 
on shore-deposits, 222 
on life extermination by cold epochs 
230 


INDEX 


553 


ee a reais tipensenaisinenyressiiaese/aesissisanssinigaienstedisaliinssesasisaneiuieensseei> 


Perwin, experiment on Helix pomatia, 
are 8 


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 
Darwin, experiments on seed-dispersal, 
e258 
on natural history of the Keeling 
Islands, 286 
on cultivated plants not running 
wild, 507 
Dawkins, Professor Boyd, on animal mi- 
grations during the glacial epoch, 
120 
_Dawson, Mr. G. M., on alternations of 
~ climate in British Columbia, 121 
Professor, on Palzeozoic boulder-beds 
in Nova Scotia, 201 
De Candolle on dispersal of seeds, 80 
Deep-sea deposits, 219 
Deer in Celebes, 4554 
Delphinium ajacis, on arailway bank, 515 
Dendreca, 19 
D. coerulea, 19 
D. discolor, 19 
D. dominica, 19 
Dendreca coronata, variation of, 58 
Dendrophidez, 28 
Denudation destroys the evidences of 
glaciation, 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 temperance of, 
132 


Diagram of excentricity and precession, 
129 
Diagram of excentricity for three million 
years, 171 
Dididez, how exterminated, 436 
Didunculus, keeled sternum of, 437 
Diospyros, in upper greensand of Green- 
land, 18 
Diplotaxis muralis, on railway banks, 513 
Dipnei, discontinuity of, 69 
Dipterus, 69 
Discontinuity 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 effected, 73,°76 
along mountain-chains, 81 
of seeds by wind, 80, 257 


Dispersal by birds, 81, 258 
by ocean currents, 81, 258 
_ of Azorean plants, facilities for, 260 
Distribution, changes of, shown by ex- 
tinct animals, 102 
how to explain anomalies of, 420 
Drontheim mountains, peculiar mosses 
of, 368 
_Dobson, Mr., on bats of Japan, 394 
on the affinities of Mystucina tuber- 
culata, 474 
Dodo, the, 436 
aborted wings of, 437 
Dryiophide, 28 
Dumeril, Professor, on lizards of Bour- 
bon, 435 


..Duncan, Professor P. M., on ancient sea 


of central Australia, 496 


E. 


Early history of New Zealand, 484 
Earth’s age, 210 
Kast Asian birds, range of, 38 
East and West Australian floras, geologi- 
cal explanation of, 494 _ 
Echidna, 30 
Echimyide, 27 
Elevation of North America during 
glacial period, 154 
causing diversion of gulf-stream, 154 
~Klwes, Mr. H. J., on distribution of 
Asiatic birds, 379a 
Emberiza scheniclus, discontinuity of, 66 
E. passerina, range of, 66 
E. pyrrhulina, 66 
Endemic genera of plants in Mauritius, 
&c., 443 
Endemic genera of plants in New Zea- 
land, 526 
English plants in St. Helena, 297 
Environment, change of, as modifying 
organisms, 225 
Eriocaulon septangulare, 363 
Ethiopian Region, definition of, 42 
birds of, 43 
.Ettingshausen, Baron von, on the fossil 
flora of New Zealand, 499 
on Australian plants in England, 518 
Eucalyptus, wide range of, in Australia, 


Eucalyptus and Acacia, why not in New 
Zealand, 507 
Eucalyptus in Eocene of Sheppey, 518 
Eupetes, distribution of, 25 
Europe, Asia, &c., as zoological terms, 32 
European birds, range of, 16 
in Bermuda, 269 
European occupation, effects of, in St. 
Helena, 294 
European plants in New Zealand, 507 
in Chile and Fuegia, 521 
Everett, Mr., on Bornean birds, 377 
“~~ on raised coral-reefs in the Philip- 
pines, 389 ; 
Evolution necessitates continuity, 70 


654 


INDEX 


Excentricity and precession, diagram of, 
129 


Excentricity, variations of, during three 
million years, 171 

Excentricity a test of rival theories of 
climate, 171 

Excentricity, high, its effects on warm 
and cold climates, 198 

Extinct animals showing changes of dis- 
tribution, 102 

Extinct birds of the Mascarene Islands, 


436 
of New Zealand, 476 
Extinction caused by glacial epoch, 122 


F. 


Families, restricted areas of, 29: 
distribution and antiquity of, 68 
Fauna and flora, peculiarities of British, 

370 


Fauna of Borneo, affinities of, 380 
of Java, 381 
of Java and Asia compared, 383. 
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 great speciality in, 343 
mode of migration of fresh-water, 344 
fresh-water, of New Zealand, 484 
Floating islands, and the dispersal of 
animals, 74 
Flora of the Azores, 256 
of Bermuda, 271 
of the Galapagos, 288 
of St. Helena, 305 
of the Sandwich Islands, 321; pecu- 
liar features of, 323 
peculiarities of the British, 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, 489 
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 
Flowers, beautiful, in Madagascar, 440 
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, 287 
Forests, submerged, 335 
Formosa, 400 
physical features of, 401 
animal life of, 401 
list of mammalia of, 402 
list of land-birds peculiar to, 404 
Fowler, Rev. Canon, on peculiar British 
coleoptera, 346, 349 
Freezing water liberates low-grade heat, 


Fresh-water deposits, extent of, 97 
organisms absent in St. Helena, 304 
snail peculiar to Ireland, 356 
fishes of the Seychelles, 432 

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 
amphibia from, 278 
reptiles of, 278 
birds of, 280 
insects of, 284 
land-shells of, 284 
flora of, 288 
and Azores contrasted, 290 
Galbula cyaneicollis, distribution of, 18 
rufoviridis, 18 
viridis, 18 
Galeopithecus, 63 
Gallinula sandvichensis, 313 
Gardner, Mr. J. 8., on Tertiary changes 
of climate, 203 
Garrulus, distribution of species of, 20 
Garrulus glandarius, 21, 23, 65 
G. cervicalis, 21 
G. krynicki, 21 
. atricapillus, 21 
. hyrcanus, 21 
. brandti, 21, 23 
. lanceolatus, 22 
. bispecularis, 22 
. Sinensis, 22 
. tairanus, 22 
G. japonicus, 22, 65~ 
Geikie, Dr. James, on interglacial de- 
posits, 121 
Sir Archibald on stratified rocks 
being found near shores, 87 
on formation of chalk in shallow 
water, 96 
on permanence of continents, 104 
on horse in rate of denudation, 
173 
on the rate of denudation, 215 
on the small amount of marine de- 
nudation, 225 
on age of buried river channels, 337 
Genera, extent of, 17 
origin of, 61 
rise and decay of, 64 


G2 F2 $2 RR RR 


INDEX 


555 


7 eee eS ee ee ee ee 


Generic areas, 17 
Generic and Family distribution, 25 
Genus, defined and illustrated, 17 
Geographical change as a cause of glacia- 
tion, 148 
changes, influence of, on climate, 
150, 152 
Geographical changes, effect of, on Arctic 
climates, 195 
changes of Java and Borneo, 384 
changes as modifying organisms, 228 
Geological climates and geographical 
conditions, 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 
aimates as affecting distribution, 
34 


climates, summary of causes of, 536 
time, summary of views on, 539 
Geology of Borneo, 375 
of Madagascar, 412 
of Celebes, 451 
of New Zealand, 472 
of Australia, 494 
Geomalacus maculosus, 357 
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 
ee ausing migration and extinction, 


causes of, 125 
the essentials. to the production of, 
iL 


36 
probable date of the, 160 
and the climax of continental de- 
velopment, 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 
widespread in recent times, 536 
Gleichenia in Greenland, 186 
in relation to chalk, 89 
Globigerina-ooze, analysis of, 91 
Globigerinz, where found, 92 
Glyptostrobus, fossil, 186 
Goats, destructiveness of, in St. Helena, 
295 


Godman, Mr., on birds reaching the 
Azores, 248, 250 - 

Gray, Professor Asa, on extinction of 
European plants by the glacial 
epoch, 123 


Great er and Japan, birds common 
0, 396 
Greene, Dr. J. Reay, on chameleons in 
Bourbon and Mauritius, 435 
apenas loss of sun-heat by clouds in, 
14 


Greenland, an anomaly in the Northern 
Hemisphere, 154 
Miocene, flora of, 183 
Cretaceous flora of, 186 
flora of ice-surrounded rocks of, 522 
Grinnell Land, fossil flora of, 184 
Groves, Messrs. H. and J., list of peculiar 
British flowering plants, 361 
Guernsey, peculiar caddis-fly in, 353 
-Gulick, Rev. J. T., on Achatinellinz, 317 
_Giinther, Dr., on gigantic tortoises, 279 
on peculiar British fishes, 341 
on Urotrichus gibsii, 394 
on lizards in the London docks, 431 
on Indian toads in Mauritius, 438 
_Guppy, Mr., on chalk of Solomon Islands, 
91 


a 


Haast, Dr., on otter-like mammal in 
New Zealand, 475 
Habitability of globe due to disproportion 
of land and water, 209 
Haplothorax burchellii, 299 
Hartlaub, Dr., on ‘‘ Lemuria,” 423, 426 
Hatteria punctata, 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 sedimentary rocks, 
219 
Hawaiian fauna and flora, antiquity 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 cloud and fogs, 145 
Hector, Dr., on Triassic and Jurassic 
’ flora of New Zealand, 526 
Heer, Professor, on chalk sea in Central 
Europe, 93 
Heilprin, Professor, on insects of Ber- 
muda, 269 
on Jand-shells of Bermuda, 270 
Helianthemum Breweri, 361 
Heliodus, an American fossil, 69 
Helix, 17 
Hemiptera of St. Helena, 303 , 
.Hemsley, Mr. W. B., on plants peculiar 
to Bermuda, 272 
on number of flowering plants in 
Madagascar, 440 
on additions to the flora of New 
Zealand, 488 
Hepatice, peculiar British, 366 vos) 
non-European genera of, in Britain. 
67 


556 


INDEX 


Hesperomys, 26 
Hesperornis allied to ostriches, 481 
High land essential to the production of 
a glacial epoch, 195 
Hildebrand, Dr. W., on flora of the 
Sandwich Islands, 321 
Himalayan birds and insects in Celebes, 
462 
Hippopotamus in Yorkshire as proving 
a mild climate, 119 
Hochstetter on the aquatic mammal of 
New Zealand, 475 
Hooker, Sir Joseph, on the Galapagos 
af flora, 288 
on affinities of St. Helena plants, 306 
on peculiar British plants, 360, 363 
on the flora of New 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 
Horne, Mr. John, on ice-sheet covering 
the Isle of Man, 115 
Hull, Professor, on Permian breccias in 
“~" Jreland indicating ice-action, 201 
Humming-birds, restricted range of, 16 
Hutton, Captain, on struthious birds of 
$m: New Zealand, 478 
Huxley, Professor, on geological time, 
211 


on European origin of African ani- 
mals, 419 
Hyomoschus, 27 
Hyracoidea, restricted range of, 30 


i, 


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 

Icteridze, 50 

Iguanidee, 50 

Indian birds in Formosa, 406 

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 


Insects 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 conti- 
nent and in North America, 121 
Interglacial periods and their 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, classification of, 242 
importance of, in study of distribu- 
tion, 241 
remote, how stocked with plants 
and animals, 261 
submerged between Madagascar and 
India, 424 
Isle of Wight, peculiar beetle of, 349 
Isatis tinctoria, on railway bank, 513 
Ithaginis, 26 


J. 


Japan, zoological features of, 393 
mammalia of, 393 
birds of, 396 
birds peculiar to, 398 
birds in distant areas, 399 
Japan and Formosa, 391 
Java, fauna of, 381 
Asiatic species in, 383 
Java and Borneo, past changes of, 384 
Jays, distribution of species of, 20 
of Europe and Japan, 67 
Jeffreys, Dr. Gwyn, on shallow-water 
mollusca 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 
audd, Prof. J. W., on absence of glacia- 

tion in east Europe, 139 
on glaciation of the Alps produced by 
elevation, 179 
Jura, travelled blocks on, 110 
Jurassic warm Arctic climate, 202 


K. 


Keeling Islands, animals of, 286 
Kelvin, Lord, on age of the earth, 213 
Kirk, Mr. T., on temporary introduced 

plants, 515 


INDEX 


Knowledge of various kinds required for 
“se of geographical distribution, 


] . 


L. 


Lagopus scoticus, 340 
Land as a barrier to ocean-currents, 150 
Land and sea, changes of, 83 
gene of, affect climate, 148, 
1 
Land and water, disproportion of, ren- 
ders globe habitable, 209 
Land-birds of Celebes, list of, 465 
Land-connection, how far necessary to 
dispersal of mammals, 73 
Land-shells, great antiquity of, 79 
universal distribution of, 79 
aga favouring the abundance of, 
9 


of the Azores, 256 
of Bermuda, 270 
of the Galapagos, 284 
of St. Helena, 304 
of the Sandwich Islands, 317 
of the Seychelles, 434 
Laurus canariensis, 260 
Legonat on animals of Bourbon, 435 
on the Solitaire, 436 
Leguminose, abundance of, in Australia, 
490 
“ Lemuria,” a supposed submerged con- 
tinent, 422-426 
Lemurs in Madagascar, 416 
Lendenfeld, Dr. R. von, on glaciation in 
~*~ the Australian Alps, 163 
Leopard, enormous range of, 14 
Lepidoptera, list of peculiar British, 346a 
Lepidosiren, 63 
Lepidosiren paradoxa and L. annectens, 


Lepidosternide, 27 

Limestone as indicating change of sea 
and land, 84 

Linnea involuta, 356 

Linaria purpurea, on railway bank, 514 

Liopelma hochstettert, in New Zealand, 
483 

Liotrichide, 29 

List of the land-birds of Celebes, 465 

Lizard peculiar to the Mascarene Islands, 


439 
Lizards of the Galapagos, 278 
local variation of colour of, 431 
of New Zealand, 483 
Lobeliaceze, abundance of, in the Sand- 
wich Islands, 324 
Locality of a species, importance of, 12 
Doddigesia mirabilis, rarity of, 16 
Lord, Mr., on species of Urotrichus, 
804 
Low-grade and high-grade heat, 145 
Lowlands nowhere covered with per- 
petual snow, 136 
Lundy Island, peculiar beetles of, 353 
Lyell, Sir Charles, on permanence of con- 
tinents, 84 


557 


Lyell, Sir Charles, on calcareous mud 90 
“2 on the distribution of chalk, 98 
on geographical causes as modifying 
climate, 148 
as of geological time, 211, 


on classification of sedimentary 


rocks, 217. 
Lynxes, a Palearctic group, 41 


M. 


.McLachlan, Mr., on peculiar British 


caddis-flies, 353 
Madagascar, physical features of, 412 
former condition of, 414 
biological features of, 416 
mammalia of, 416 
reptiles of, 417 
relation of, to Africa, 418 
early history of, 419 
birds of, in relation to ‘“‘ Lemuria,” 
422 
flora of, 439 
apr aseey on fauna and flora of, 
44 
great antiquity of, 446 
Madagascar and Africa, contrast of, 6 
Maillard on animals of Bourbon, 435 
Malay Islands, local peculiarities of flora 
in, 187 
past history of, 389 
Malayan birds in Formosa, 406 


Mammalia of East Asia, range of, 34 


of North Africa, range of, 34 
Mammalia, dispersal of, 73 
of Britain, range of, 33 
poverty of, 329 
of Borneo, 376 
of Java, 382 
of the Philippines, 386 
of Japan, 393 
of Formosa, 402 
common to Formosa and India, 403 
of Madagascar, 416 
of Comoro Islands, 428 
of Celebes, 455a, whence derived, 456 
of New Zealand, 474 
Maori legend of origin of the forest-rat, 
475 
Maoris, their accounts of the moa, 477 
Map of the old Rhone glacier, 110 
of North and South Polar Regions, 
138 
of the Azores, 248 
of Bermuda, 263 
of the Galapagos, 276, 277 
of the South Atlantic Ocean, 293 
of the Sandwich Islands, 311 
of the North Pacific with its sub- 
merged banks, 312 
of British Isles and the 100-fathom 
bank, 333 
of Borneo and Java, 374 
of Japan and Formosa, 392 
physical, of Madagascar, 413 
of the Madagascar group, 415 


558 


INDEX 


Map of the Indian Ocean, 425 
of Celebes, 452 
of i bottom around New Zealand, 
472 
of Australia in Cretaceous period, 


’s 
Marcou, Professor Jules, on the Pliocene 
and glacial epochs, 233 
Marmot, range of, 15 
Mars as illustrating glacial theories, 164, 
8 


no true ice cap on, 166 
Marsupials, range of, 30 
Marsh, Prof. O. C., on the Atlantosaurus, 
, 98 
on Hesperornis, 481 
Marsh, Mr., on camels as desert-makers, 
z 296 


Mascarene Islands, 428-445 
Mascarene plants, curious relations of, 


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 New Zealand, 515 
Megalzemide, 27 
Meleagris, 50 
Melilotus vulgaris, on railway banks, 


513 
Meliphagide, 47 
Mellis, Mr., on the early history of St. 
Helena, 295 
Melospiza melodia, variation of, 58 
Merycotherium, 123 
Meteorological causes as intensifying 
glaciation, 142 
Meyer, Dr. A. B., list of mammals of 
Celebes, 455a 
on birds of Celebes, 457, 459b 
Migration caused by glacial epoch, 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 a 
of plants from north to south, long 
continued, 518 
of plants aided by geological changes, 
519 


of plants by way 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, 198 
summary of causes of, 537 


$e 
— 


Miocene Arctic flora, 183 
flora of Europe, 123 
or Eocene floras, 185 
deposits of Java, 385 
ee of Europe and North India, 
4 
Mississippi, matter carried away by, 172 
Mitten, Mr. William, on peculiar British 
mosses and hepaticee, 365, 368 
On. Loran appearance of plants, 


Mniotiltidz, a nearctic group, 49 
Mnium, peculiar species of, in the Dront- 
heim mountains, 368 
Moas of New Zealand, 476 
Mollusca, dispersal of, 78 
Monotremata, restricted range of, 30 — 
Moraines, 108 
of Ivrea, 116 
More, Mr. A. G., on peculiar Irish plants, 


364 
Morgan, Mr. C. Lloyd, on thickness of 


formations not affected by denu- 
dation, 220 
Moseley, Mr. H. N., on seeds carried by 
=" pirds, 259 
on the flora of Bermuda, 272 
Mosses, peculiar British, 366 
non-European genera of, in Britain, 
3 


how diffused and why restricted, 
68 


Mt. St. Elias, why not ice-clad, 154 
Mountain chains aiding the dispersal of 
plants, 61 
as aids to migration of plants, 513 
Mueller, Baron von, census of Australian 
plants, 492 
Murray, Sir J., on oceanic deposits, 86 
~ onchalk-like globigerina-ooze, 92 
on mean height of continents, 216 
on land-area of the globe, 221 
Mus, 17, 26 
Mygale pyrenaica, range of, 15, 24 
M. muscovitica, 24 
Myrica faya, 260 
Myrsine, fossil in Greenland, 186 
Mytilus edulis, sub-fossil in Spitzbergen, 
182 


N. 


_Nares, Capt. Sir G., on snow and ice in 


high latitudes, 135 
on abrupt elevation of Bermuda, 264 
Nearctic Region, definition of, 48 
mammailia of, 48 
birds of, 49 
reptiles of, 50 
Nectarinea osea, restricted range of, 16 
Neilgherries, Australian plants, natura- 
lized in, 528 
Neotropical Region, definition of, 51 
low types of, 52 


Nevill, Mr. Geoffrey, on land-shells of 


the Seychelles, 434 
on destruction of Seychelles flora, 
445 


INDEX 


559 


New species, origin of, 56 
Newton, Mr. E., on short wings of the 
“’" Seychelles dove, 437 
Newton, Professor, on recently extinct 
— birds, 487 
Newts, restricted range of, 30 
New Zealand, recent glaciation of, 163 
New Zealand, 471 
geology of, 472 
form of sea-bottom around, 473 
zoological character of, 473 
mammalia of, 474 
wingless birds of, 476 
past changes of, 478 
winged birds and lower vertebrates 
of, 482 
deductions from peculiarities of 
fauna of, 484 
period of its union with N. Australia, 
484 
the flora of, 487, 506 
origin of Australian element in the 
flora of, 498 
tropical character 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, 526 
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 8. temper- 
ate America, 521 
hemisphere, absence of southern 
plants from, 527 
flora, hardiness of, 528 


O. 


Ocean-currents as carriers of plants, 81 
as affecting interglacial periods, 152 
as determining climate, 153 
effects of, in Tertiary times, 196 
Oceans, Darwin on permanence of, 100 
fresh arguments for permanence 
of, 105 
Oceanic and continental islands, 242 
Oceanic islands a proof of the perman- 
ence of oceans, 100 
Oceanic islands, 244 
—the Azores, 247 
géneral remarks on, 329 
Octodontide, 27 
Gnanthe fluviatilis, 362 
(ninghen, Miocene flora of, 183 
Gnothera odorata, on a railway bank, 
514 


Ophrys apifera, temporary appearance of, 
514 


papa species have restricted ranges, 
505 ; 
Orchids, abundance of, in Bourbon and 
Mauritius, 446 
bars Baas universal in the tropics, 
44 
Orders, distribution of, 30 
Organic change dependent on change 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, 289 
of the beetles of St. Helena, 298 
of the 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 
Overlapping and discontinuous areas, 28 


FP. 


Palearctic Region, limits of, 39 
characteristic features of, 41 
Paleozoic formations, depths of, round 
London, 218 

Palm confined to Round Island, 444 
Panax, fossil in Greenland, 186 

Papilio, 17 

Paraguay, no wild horses or cattle in, 226 
Parnassius, Palearctic, 42 
Parus ater, 19 
. borealis, 19, 64 

britannicus, 321 

camtschatkensis, 19 

cinctus, 20 

ceruleus, 20 

cyaneus, 20 

cristatus, 20 

ledouci, 20 

lugubris, 20 

major, 19 
palustris, 19; discontinuous area of, 65 
. (acredula) rosea, 340 
P. teneriffe, 20 
Passeres of the Sandwich Islands, 315 
Past changes of New Zealand, 478 
Payer, Lieut., on evaporation of ice dur- 

~ ing the Arctic summer, 140 
Peculiar fauna of New Zealand, deduc- 
tions from, 484 
Pengelly, Mr., on submerged forests, 334 
“Pennula ecaudata, in Sandwich Islands, 
313 
Permanence of continents, summary of 
evidence for, 103 
Permian formation, indications of ice- 
action in, 200 


hhh hhh hhh: 


~ 


560 


INDEX 


Perodicticus, a local genus, 26 
Petroselinum segetum, on railway bank, 
514 
Philippine Islands, 386 
mammalia of, 386 
birds of, 387 
past history of, 389 
Phyllodactylus galapagensis, 279 
Phylloscopus borealis, range of, 15 
Physical causes which determine distri- 
bution, 533 
features of Formosa, 401 
Pica, 17 
Pickering, Dr., on the flora of the Sand- 
wich Islands, 323 
on temperate forms on mountains of 
the Sandwich Islands, 323 
Pithecia monachus, distribution of, 18 
P. rufibarbata, 18 
Pitta, distribution of, 25 
Piants, dispersal of, 80 
seeds of, adapted for dispersal, 80 
wide range of species and genera of, 
1 


poverty of, in Ireland, 339 

peculiar British, 361 

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 they migrate from north to 
south, 512 

of existing genera throughout the 
Tertiary period, 520 

southern migration of, by way of the 
Himalayas, 523 


southern migration of, through 
Africa, 524 

endemic genera of, in New Zealand, 
526 


Platypus, 30 
Plestiodon longirostris of Bermuda, 266 
Po, matter carried away by, 173 
Podargus, Australian genus, 47 
Peecilozonites, peculiar to Bermuda, 271 
Poinciana regia in Madagascar, 440 
Populus, fossil in Spitzbergen, 184 
~Rourtales, 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, 18 
Pteroptochide, 29 
Pyrenean ibex, restricted range of, 15 


R. 
Railways, new plants on, 513 


Ramsay, Mr. Wardlaw, on Philippine 
™ birds, 388 


Ramsay, Professor, on ancient land sur- 
faces, 99 
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 the Seychelles, 430 
of Mauritius and Round Island, 438 
of New Zealand, 483 
Rhodolena altivola in Madagascar, 440 
Ridgway, Mr., on birds of Galapagos, 281 
River-channels, buried, 336 
Roches moutonnées, 108 
Rodents in Madagascar, 417 
Round Island, a snake and a palm pecu- 
liar to, 438, 444 
Rumex pulcher in New Zealand, 515 
e, Mr. E. C., on peculiar British in- 
sects, 345, 351 , 


8. 


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 
Sandwich Islands, the, 310 
zoology of, 313 
birds of, 313 
reptiles of, 316 
land-shells of, 317 
insects of, 318 
vegetation of, 321 
antiquity of fauna and flora of, 328 
Sassafras, in Swiss Miocene, 183 
Scandinavian flora, aggressive power of, 
511 
Scientific voyages, comparative results 
or, 
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 
ioe tuberculatus in New Zealand 
474 


INDEX 


Scrophularineze, why few species are 
common to Australia and New 
Zealand, 505 

Sea, depth of, around Madagascar, 414 

depth of, around Celebes, 452 

Sea-bottom around New Zealand and 
Australia, 473 

Sea-level, changes of, dependent on gla- 
ciation, 161 

gam effects of glaciation on, 162, 
4 
rise of, a cause of denudation, 174 

Seas, inland, in Tertiary period, 191 

Section of sea-bottom near Bermuda, 264 

Sedges and grasses common to Australia 
and New Zeaiand, 504 

Sedimentary rocks, how to estimate 
thickness of, 217 

thinning out of, 217 
how formed, 218 
thickness of, 217, 221 
summary of conclusions on the rate 
of formation of the, 221 
Seebohm, Mr., on Parus palustris, 65 
on Emberiza scheniclus, 66 
on snow in Siberia, 166 
on birds of Japan, 396 
Seeds, dispersal of, 257 
carried by birds, 258 
Senecio australis, on 


burnt ground, 


Sericinus, Palearctic, 42 
Seychelles Archipelago, 429 
birds of, 430 
reptiles and amphibia of, 430 
fresh-water fishes of, 432 
land-shells of, 434 
Sharp, Dr. D., on beetles of the Sand- 
=~ wich Islands, 319 
on peculiar British beetles, 345 
Shelford, Mr. R., on peculiar mammals 
~™ "and birds of Borneo, 376 
Shells, peculiar to Britain, 357 
Shetland Isles, peculiar beetle of, 352 
plants new to Britain in, 370 
Shore deposits, 85, 211 
proving the permanence of conti- 
nents, 97 
distance from coast of, 221 
Sialia sialis, variation of, 58 
Siberia, amount of snow and its sudden 
disappearance in, 166 
Silurian boulder-beds, 201 
warm Arctic climate, 202 
Simiidae, 27 
Sisyrinchium bermudianum, 272 
Skertchley, Mr., on four distinct boulder- 
“Clays, 118 
on Tertiary deposits in Egypt and 
Nubia, 191 
on climatic stability of present epoch, 


233 
Slug peculiar to Ireland, 357 
Snake peculiar to Round Island, 438 
Snakes of the Galapagos, 280 
of the Seychelles, 431 
Snow and ice, properties of, in relation 
to climate, 131 


561 


Snow, effects of, on climate, 188 
— of heat required to melt, 
often of small amount in high lati- 

tudes, 135 
never perpetual on lowlands, 136 
oe determining perpetual, 
maintains cold by reflecting the solar 
heat, 144 
Snow-line, alterations of, causing migra- 
tion of plants, 516 
Sollas, Mr. J. W., on greater intensity of 
telluric action in past time, 223 

South Africa, recent glaciation of, 163 
mene northern genera of plants in, 
its supposed connection with Aus- 

tralia, 525 
South Pm aacieyae plants in New Zealand, 
South Temperate America, poor in 
species, 53 
climate of, 146 
Southern flora, comparative tenderness 
of, 528 
Southern plants, 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, 63 
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, 64 

Spiranthes romanzoviana, 365 

Spitzbergen, Miocene flora of, 184 
absence of boulder-beds in, 187 


Spruce, Dr. Richard, on the dispersion 


of hepaticee, 369 

Stability of extreme glacial conditions, 
159 

Stainton, Mr. H. T., on peculiar British 
moths, 346 

Stanivoi mountains, why not ice-clad, 


Starlings, genera of, in New Zealand, 
482 

Stellaria media, temporary appearance 
of, 515 

Sternum, process of abortion of keel of, 
437 

Stow, Mr. G. W., on glacial phenomena 

in South Africa, 163 

Stratified rocks formed near shores, 85, 

8 


deposits, how formed, 218 
Striated rocks, 107 
blocks in the Permian formation, 
200 
Strix flammea, range of, 15 
Struthiones, 30 
Struthious birds of New Zealand as indi- 
cating past changes, 478 
Stylidium wide range of, 185 


562 


INDEX 


Submerged forests, 334 

Subsidence of Isthmus of Panama, 151 
Sumatra, geology of, 385 

Sweden, two deposits of “ till ” in, 121 
Swimming powers of mammalia, 74 
Swinhoe, Mr. Robert, researches in For- 
mosa, 400 

Switzerland,interglacial warm periods in, 


Sykes, Mr. E. R., on land-shells of Ber- 
muda, 270 
of the Sandwich Is., 317a 
Sylviade, overlapping genera of, 29 


T 


Talpide, a Palearctic group, 41 
Tapirs, distribution of, 25 
former wide range of, 393 
Tarsius, 63 
Tarsius fuscus in Celebes, 455a 
Tasmania and North Australia, resem- 
blance of, 5 
route of Arctic plants to, 520 
Taylor, J. W., on endemic land and 
fresh water mullusca of the British 
Isles, 354 
List of ditto, 375 
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 
aia 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 Palearctic genus, 42 

-Thomas, Mr. Oldfield, on mammalia of 
Japan, 394 

.Thomson, Sir Wyville, on organisms in 
the globigerina-ooze, 89 

analysis of globigerina-ooze, 91 
Thryothorus bewickii, discontinuity of, 


68 
“Till” of Scotland, 112 
several distinct formations of, 121 
Tits, distribution of species of, 19 
Torreya, fossil in Spitzbergen, 186 
Tortoises of the Galapagos, 278 
Trade-winds, how modified by a glacial 
epoch, 142 
Tragulide, 27 
Travelled blocks, 109 
Tremarctos, an isolated genus, 29 
Triassic warm Arctic climate, 200 
Tribonyx not a New Zealand genus, 
483 
Trichoptera peculiar to Britain, 353 
Trogons, distribution of, 28 


Tropical affinities of New Zealand birds, 
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 
Tutt, Mr. W., on peculiar British 
Lepidoptera, 346a. 


Tylor, A., on estimating the rate of denu- 


dation, 214 
Tyrannidez, an American family, 50 


U 


Uraniidez, 28 

Uropeltide, 30 

Urotrichus, distribution of, 25 
Ursus, 26 


¥. 


Variation in animals, 57 
amount of, in N. 
58 
Vegetation, local peculiarities of, 185 
effects of Polar night on, 198 
Vesperugo serotinus, range of, 14 
Vireo bellii, supposed discontinuity of, 
68 


American birds, 


Vireonidz, an American family, 49 


W. 
Wallich, Dr., on habitat of globigerine, 
92 


Warm climates of northern latitudes, long 
persistence of, 201 

Warren, Mr. W., information on British 
lepidoptera, 346a 

Water,properties of,in relation to climate, 
131, 133 

Waterhouse, Mr., on Galapagos beetles, 
284 


Wales, peculiar fish of, 341 


Watson, Mr. H. C., on the flora of the 


Azores, 256 
on peculiar British plants, 359 
on vegetation of railway banks, 513 
Webb, Mr., on comparison of Mars and 
the Earth, 166 
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, 
* 378 
Wilson, Mr. Scott B., on birds of the 
~  §§andwich Islands, 814 


INDEX 


568 


Winged birds of New Zealand, 482 
Wingless birds never inhabit continents, 


their evidence against ‘‘ Lemuria,” 
438 
of New Zealand, 476 
Wings of struthious birds show retrograde 
development, 437 
Winter temperature of Europe and Amer- 
ica, 196 
Wolf, range of, 14 
Wollaston, Mr. T. V., on insular character 
of St. Helena, 294 
on St. Helena shells and insects, 


297 
Wood, Mr. Searles V., jun., on formation 
of ‘‘ till,” 114 


on alterations of climate, 118 

on causes of glacial epochs, 125 

conclusive objection to the excen- 
tricity theory, 160 

on continuous warm Tertiary cli- 
mates, 180 

Woodward, Dr. S. P., on Ammonites 
“ living in shallow water, 95 


THE 


| Woodward, Mr., on ‘f Lemuria,” 426 


Wright, Dr. Percival, on lizards of the 
umn" Seychelles, 431 


Be 


Young, Professor J., on contemporaneous 
formation of deposits, 221 
Young Island, lofty Antarctic, 522 


Z. 


Zoology of the Azores, 248 
of Bermuda, 266 
of the Sandwich Islands, 313 
of Borneo, 376 
of Madagascar, 416 
of islands round Celebes, 453 
of Celebes, 455 
Zoological and geographical regions com- 
pared, 32, 54 
Zoological features of Japan, 393 
character of New Zealand, 473 


END 


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