(navigation image)
Home American Libraries | Canadian Libraries | Universal Library | Community Texts | Project Gutenberg | Children's Library | Biodiversity Heritage Library | Additional Collections
Search: Advanced Search
Anonymous User (login or join us)
Upload
See other formats

Full text of "Island Life: Or, The Phenomena and Causes of Insular Faunas and Floras, Including a Revision and ..."

Google 



This is a digital copy of a book that was preserved for generations on library shelves before it was carefully scanned by Google as part of a project 

to make the world's books discoverable online. 

It has survived long enough for the copyright to expire and the book to enter the public domain. A public domain book is one that was never subject 

to copyright or whose legal copyright term has expired. Whether a book is in the public domain may vary country to country. Public domain books 

are our gateways to the past, representing a wealth of history, culture and knowledge that's often difficult to discover. 

Marks, notations and other maiginalia present in the original volume will appear in this file - a reminder of this book's long journey from the 

publisher to a library and finally to you. 

Usage guidelines 

Google is proud to partner with libraries to digitize public domain materials and make them widely accessible. Public domain books belong to the 
public and we are merely their custodians. Nevertheless, this work is expensive, so in order to keep providing tliis resource, we liave taken steps to 
prevent abuse by commercial parties, including placing technical restrictions on automated querying. 
We also ask that you: 

+ Make non-commercial use of the files We designed Google Book Search for use by individuals, and we request that you use these files for 
personal, non-commercial purposes. 

+ Refrain fivm automated querying Do not send automated queries of any sort to Google's system: If you are conducting research on machine 
translation, optical character recognition or other areas where access to a large amount of text is helpful, please contact us. We encourage the 
use of public domain materials for these purposes and may be able to help. 

+ Maintain attributionTht GoogXt "watermark" you see on each file is essential for in forming people about this project and helping them find 
additional materials through Google Book Search. Please do not remove it. 

+ Keep it legal Whatever your use, remember that you are responsible for ensuring that what you are doing is legal. Do not assume that just 
because we believe a book is in the public domain for users in the United States, that the work is also in the public domain for users in other 
countries. Whether a book is still in copyright varies from country to country, and we can't offer guidance on whether any specific use of 
any specific book is allowed. Please do not assume that a book's appearance in Google Book Search means it can be used in any manner 
anywhere in the world. Copyright infringement liabili^ can be quite severe. 

About Google Book Search 

Google's mission is to organize the world's information and to make it universally accessible and useful. Google Book Search helps readers 
discover the world's books while helping authors and publishers reach new audiences. You can search through the full text of this book on the web 

at |http: //books .google .com/I 



T i'i c T IM OTHY I l o PKtNa-seqw 



\ 


A 
i 

* 


I! 

1 


P- 




^ 


PiK 



IJEiLAHB'SKM''ffl[^i|VmOiR°VNl!VS!?SiniT 
«. .BioLUL 



mi 



/ 



Cf*" 



ff 



ISLAND LIFE 



OR, THE PHENOMENA AND CAUSES OF 



INSULAR FAUNAS AND FLORAS 



XNCLCDIXO 
A REVISION AND ATTEMPTED SOLUTION OP THE PROBLEM OP 

GEOLOGICAL CLIMATES 



BY 

ALFRED RUSSEL WALLACE 

AUTHOR or **THK GEOGRAPHICAL DISTRIBmOS OF AKIMALS" 
*'THS MALAY ARCHIPELAGO** XTC. 



NEW YORK 

HARPER k BROTHERS, FRANKLIN SQUARE 

1881 



WIS 



249253 









• • 






• • 



e k • 






9 



TO 



SIR JOSEPH DALTON HOOKER 

K«C<8tIt| C«B«| <.n*8<| £TC«| ETC* 

WHO, MORE THAN ANT OTHER WRITER, HAS ADVANCED OUR KNOWLEDGE 

OF THE GEOGRAPHICAL DISTRIBL-TION OF PLANTS, AND 

ESPECTALLY OF INSULAR FLORAS 

3 DtVxcatt tl]i0 Uolttme 

ON A KINDRED SUBJECT, AS A TOKEN OF 
ADMIRATION AND REGARD 



PREFACE. 



The present volume is the result of four years' additional 
thought and research on the lines laid down in my " Geograph- 
ical Distribution of Animals," and may bo considered as a pop- 
ular supplement to and completion of that work. 

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

The full statement of the scope and object of the present 
essay given in the " Introductory " chapter, together with the 
" Summary " of the whole work and the general view of the 
more important arguments given in the " Conclusion," render it 
unnecessary for me to oflfer any further remarks on these points. 
I may, however, state generally that, so far as I am able to 



vi PREFACE. 

jadge, a real advance has here been made in the mode of treat- 
ing problems in geographical distribution, owing to the firm 
establishment of a number of preliminary doctrines or " prin- 
ciples," which in many cases lead to a far simpler and yet more 
complete solution of such problems than has been hitherto pos- 
sible. The most important of these doctrines are those which es- 
tablish and define — (1) The former wide extension of all groups 
now discontinuous, as being a necessary result of " evolution ;" 
(2) The permanence of the great features of the distribution of 
land and water on the earth's surface ; and (3) The nature and 
frequency of climatal changes throughout geological time. 

I have now only to thank the many friends and correspond- 
ents who have given me information or advice. Besides those 
whose assistance is acknowledged in the body of the work, I 
am especially indebted to four gentlemen who have been kind 
enough to read over the proofs of chapters dealing with ques- 
tions on which they have special knowledge, giving me the ben- 
efit of valuable emendations and suggestions. Mr. Edward R. 
Alston has looked over those parts of the earlier chapters which 
relate to the mammals of Europe and the north temperate 
zone ; Mr, S. B. J. Skertchley, of the Geological Survey, has 
read the chapters which discuss the glacial epoch and other ge- 
ological questions ; Professor A. Xcwton has looked over the 
passages referring to the birds of the Madagascar group ; while 
Sir Joseph D. Hooker has given me the invaluable benefit of 
hia remarks on my two chapters dealing with the New Zealand 
flora. 



CONTENTS. 



PAET I. 

THE DISPERSAL OP ORGANISMS : ITS PHENOMENA, LAWS, 

AND CAUSES. 

CHAPTER L 

INTRODUCTORY. 

RemarkAble Contrasts in Distribation of Animals. — Britain and Japan. — Australia 
and New Zealand. — Bali and Lombok. — Florida and Bahama Islands. — Brazil 
and Africa. -^Borneo, Madagascar, and Celebes. — Problems in Distribation to be 
Fonnd in every Country. — Can be Solved only by the Combination of many Dis- 
tinct Lines of Inquiry, Biological and Physical. — Islands Offer the Best Subjects 
for the Study of Distribution. — Outline of the Subjects to be Discussed in the 
Present Volume Pages 3-11 

CHAPTER II. 

THE ELEMENTARY FACTS OF DISTRIBUTION. 

Importance of Locality as an Essential Character of Species. — Areas of Distribution. 
— ExtenLand Limitations of Specific Areas. — Specific Range of Birds. — Generic 
Areas. — Separate and Overlapping Areas. — The Species of Tits as Illustrating 
Areas of Distribation. — The Distribution of the Species of Jays. — Discontinuous 
Generic Areas. — Peculiarities of Generic and Family Distribution.^General Feat- 
ures of Overlapping and Discontinuous Areas. — Restricted Areas of Families. — 
The Distribation of Orders. 12-29 

CHAPTER in. 

CLASSIFICATION OF .THE FACTS OF DISTRIBUTION. — ZOOLOGICAL REGIONS. 

The Greographical Divisions of the Globe do not Correspond to Zoological Divisions. 
— The Range of British Mammals as Indicating a Zoological Region. — Range of 
East Asian and North African Mammals. — The Range of British Birds. — Range 
of East Asian Birds. — The Limits of the Palsearctic Region. — Characteristic Feat- 
ures of the PaloMirctic Region. — Definition and Characteristic Groups of the Ethi- 
opian Region.^Of the Oriental Region.— Of the Australian Region. — Of the Ne- 
arctic Region. — Of the Neotropical Region. — Comparison of Zoological Regions 
with the Geographical Divisions of the Globe 30-52 



viii CONTENl^. 



CHAPTER IV. 

EVOLUTION AS THE KE7 TO DISTRIBUTION. 

Importance of the Doctrine of Evolution. — The Origin of New Species. — Variation 
in Animals. — The Amount of Variation in North American Birds. — How New Spe- 
cies Arise from a Variable Species. — Definition and Origin of Genera. — Cause of 
the Extinction of Species. — The Rise and Decay of Species and Genera. — Discon- 
tinuous Specific Areas, why IIslyq. — Discontinuity of the Area of Partis palustria. 
— Discontinuity of Emberlza schanicius, — The European and Japanese Jays. — 
Supposed Examples of Discontinuity among North American Birds. — Distribution 
and Antiquity of Families. — Discontinuity a Proof of Antiquity. — Concluding 
Kemarks Pages 63-67 

CHAPTER V. 

THE POWERS OF DISPERSAL OF ANIMALS AND PLANTS. 

Statement of the General Question of Dispersal. — The Ocean as a Barrier to the 
Dispersal of Mammals. — The Dispersal of Birds. — The Dispersal of Reptiles. 
— The Dispei*Siil of Insects. — The Dispersal of Land Molhisca. — Great An- 
tiquity of Land Shells. — Causes Favoring the Abundance of Land Shells.— The 
Dispersal of Plants. — Special Adaptability of Seeds for Dispei'siil. — Birds as 
Agents in the Dispersal of Seeds. — Ocean Currents as Agents in Plant-dispersal. 
— Dispersal along Mountain-chaius. — Antiquity of Plants as Affecting their Dis- 
tribution C8-78 

CHAPTER VI. 

GEOGRAPHICAL AND GEOLOGICAL CHANGES : THE PERMANENCE OF 

CONTINENTS. 

Changes of Land and Sea, their Nature and Extent. — Shore-deposits and Stratified 
Koci^s. — The Movements of Continents. — Supposed Oceanic Formations; the 
Origin of Chalk. — Fresh -water and Shore Deposits as Proving the Permanence of 
Continents. — Oceanic Islands as Indications of the Permanence of Continents and 
Oceans. — Geneml Stability of Continents with Constant Change of Form. — Effect 
of Continental Changes on the Distribution of Animals. — Changed Distribution 
Proved by the Extinct Animals of Different Epochs. — Summary of Evidence for 
the General Permanence of Continents and Oceans 70-100 

CHAPTER VII. 

CHANGES OF CLIMATE WHICH HAVE INFLUENCED THE DISPERSAL OF 

ORGANISMS : THE GLACIAL EPOCH. 

Pi*oofs of the Recent Occurrence of a Glacial Epoch. — Moraines. — Travelled Blocks. 
— Glacial Deposits of Scotland: the "Till." — Inferences from the Glacial Phe- 
nomena of Scotland. — Glacial Phenomena of North America. — Effects of the Gla- 



CONTENTS. ix 

cial Epoch on Animal Life. — Warm and Cold Periods. — Palaeontological Evidence 
of Alternate Cold and Warm Periods. — Evidence of Interglacial Wann Periods 
on the Continent and in North America. — Migrations and Extinctions of Organ- 
isms Caused by the Glacial Epoch Pages 101-118 

CHAPTER VIIL 

THE CAUSES OF GLACIAL EPOCHS. 

Various Suggested Cause?. — Astronomical Causes of Changes of Climate. — Differ- 
ence of Temperature Caused by Varying Distance of tiie Sun. — Properties of Air 
and Water, Snow and Ice, in Relation to Climate. — Effects of Snow on Climate. — 
High Land and Great Moisture Essential to the Initiation of a Glacial Epoch. — 
Perpetual Snow nowhere Exists on Lowlands. — Conditions Determining the Pres- 
ence or Absence of Perpetual Snow.— EflSciency of Astronomical Causes in Pro- 
ducing Glaciation. — Action of Meteorological Causes in Intensifying Glaciation. 
— Summary of Causes of Glaciation. — Eftect of Clouds and Fog in Cutting off* the 
Sun's Heat. — South Temperate America as Illustrating the Influence of Astronomi- 
cal Causes on Climate. — Geogmphical Changes, how far a Cause of Glaciation. — 
Land Acting as a Barrier to Ocean Currents. — The Tiieory of Interglacial Periods 
and their Probable Character.— Probable Effect of Winter in Aphelion on the Cli- 
mate of Biitain. — Tiie Essential Piinciple of Climatal Change Restated. — Prob- 
able Date of tlie Last Glacial Epoch. — Changes of the Sea-level Dependent on 
Glaciation. — The Planet Mars as Bearing on the Theory of Eccentricity as a 
Cause of Glacial Epochs 119-lCO 

CHAPTER IX. 

ANCIENT GLACIAL EPOCHS, AND MILD CLIMATES IN THE ARCTIC REGIONS. 

Dr. CroU's Views on Ancient Ghicial Epochs. — Effects of Denudation in Destroying 
the Evidence of Remote Ghicial Epochs. — Rise of Sea-level Connected with 
Glacial Epochs a Cause of Further Denudation. — What Evidence of Early Glacial 
Epochs may be Expected. — Evidences of Ice-action during the Tertiary Period. 
— The Weight of the Negative Evidence. — Temperate Climates in the Arctic Re- 
gions. — The Miocene Arctic Flora. — Mild Arctic Climates of the Cretaceous 
Period. — Stratigrnphical Evidence of Long-continued Mild Arctic Conditions. — 
The Causes of Mild Arctic Climates. — Geographical Conditions Favoring Mild 
Northern Climates in Tertiary Times. — ^The Indian Ocean as a Source of Heat in 
Tertiary Times. — Condition of North America during the Tertiary Period. — 
Effect of High Eccentricity on Warm Polar Climates. — Evidences as to Climate 
in the Secondary and Palaeozoic Epochs. — Warm Arctic Climates in Early Sec- 
ondary and Palaeozoic Times. — Conclusions as to the Climates of Secondary and 
Tertiary Periods. — General View of Geological Climates as Dependent on the 
Physical Features of the Plarth*s Surface. — Estimate of the Comparative Effects 
of Geographical and Physical Causes in Producing Changes of Climate.. lGl-199 



X CONTENTS. 

CHAPTER X. 

THE EARTH^S AGE, AND THE RATE OF DEVELOPMENT OF ANIMALS AND 

PLANTS. 

Vaiioas Estimates of Geological Time. — Denudation and Deposition of Strata as a 
Measm'e of Time. — How to Estimate the Thickness of the Sedimentary Rocks. — 
How to Estimate the Average Kate of Deposition of the Sedimentary Rocks. — 
The Rate of Geological Change probably Greater in very Remote Times. — ^Value of 
the Preceding Estimate of Geological Time. — Organic Modification Dependent on 
Change of Conditions. — Geographical Matations as a Motive Power in Bringing 
about Organic Changes. — Climatal Revolutions as an Agent in Producing Organic 
Changes. — Present Condition of the Earth one of Exceptional Stability as regards 
Climate. — Date of Last Glacial Epoch, and its Bearing on the Measurement of 
Geological Time. — Concluding Remarks. Pages 200-226 



PAKT II. 

INSULAR FAUNAS AND FLORAS. 
CHAPTER XI. 

THE CLASSIFICATION OF ISLANDS. 

Importance of Islands in the Study of the Distribution of Organisms. — Classifica- 
tion of Islands with Reference to Distribution. — Continental Islands. — Oceanic 
Islands 229-233 

CHAl^ER XII. 

OCEANIC ISLANDS. — THE AZORES AND BERMUDA. 

The Azores, or Western Islands. — Position and Physical Features. — Chief Zo- 
ological Features of the Azores. — Birds. — Origin of the Azorean Bird Fauna. — 
Insects of the Azores. — Land Shells of the Azores. — The Flora of the Azores. — 
The Dispersal of Seeils. — Birds as Seed-camers. — Facilities for Dispersal of Azo- 
rean Plants. — Important Deduction from the Peculiarities of the Azorean Fauna 
and Flora 234-249 

Bermuda. — Position and Physical Features. — The Red Clay of Bermuda. — Zoology 
of Bermuda. — Birds of Bermuda.— Comparison of the Bird Faunas of Bermuda and 
the Azores. — Insects of Bermuda. — Land MoUusca. — PMora of Bermuda. — Con- 
cluding Remarks on the Azores and Bermuda 249-275 

CHAPTER XIII. 

THE GALAPAGOS ISLANDS. 

Position and Physical Features. — Absence of Indigenous Mammalia and Ampliibia. 
— Reptiles. — Bii-ds. — Insects and Land Shells. — ^The Keeling Islands as Illustrat- 



CONTENTS. xi 

ing the Manner in which Oceanic Islands are Peopled. — Flora of the Galapagos. 
— Origin of the Flora of the Galapagos. — Concluding Remarks. . . .Pages 261-275 

CHAPTER XIV. 

ST. HELENA. 

Position and Physical Features of St. Helena. — Change Effected by European Oc- 
cupation. — The Insects of St. Helena. — Coleoptera. — Peculiarities and Origin of 
the Coleoptera of St. Helena. — Land Shells of St. Helena. — Absence of Fresh- 
water Organisms. — Native Vegetation of St. Helena. — The Relations of the Sr. 
Helena Compositae. — Concluding Remarks on St. Helena 276-293 

CHAPTER XV. 

THE SANDWICH ISLANDS. 

Position and Physical Features. — Zoology of the Sandwich Islands. — Birds. — Rep- 
tiles. — Land Shells. — Insects. — Vegetation of the Sandwich Islands. — Peculiar 
Features of the Hawaiian Flora. — Antiquity of the Hawaiian Fauna and Flora. — 
Concluding Observations on the Fauna and Flora of the Sandwich Islands. — Gen- 
eral Remarks on Oceanic Islands 203-SOG 

CHAPTER XVI. 

CONTINENTAL ISLANDS OF RECENT ORIGIN : GREAT BRITAIN. 

Characteristic Features of Recent Continental Islands. — Recent Physical Changes 
of the Britiiih Isles. — Proofs of Former Elevation. — Submerged Forests. — Buried 
River Channels. — Time of Last Union with the Continent. — Why Britain is Poor 
in Species. — Peculiar British Birds. — Fresh-water Fishes. — Cause of Great Spe- 
ciality in Fishes. — Peculiar British Insects. — Lepidoptera Confined to the British 
Isles. — Peculiarities of the Isle of Man Lepidoptera. — Coleoptera Confined to 
the British Isles. — ^Trichoptera Peculiar to the British Isles. — Land and Fresh- 
water Shells. — Peculiarities of the British Flora. — Peculiarities of the Irish Flora. 
— Peculiar British Mosses and Hepaticae. — Concluding Remarks on the Peculiari- 
ties of the British Fauna and Flora S07-341 

CHAPTER XVn. 

BORNEO AND JAVA. 

Position and Physical Features of Borneo.— Zoological Features of Borneo: Mam- 
malia. — Birds. — The AfiSnities of the Bomean Fauna.— Java, its Position and 
Physical Features. — General Character of the Fauna of Java. — Differences be- 
tween the Fauna of Java and that of the other Malay Islands. — Special Relations 
of the Javan Fauna to that of the Asiatic Continent. — Past Geographical Ciianges 
of Java and Borneo. — The Philippine Islands. — Concluding Remarks on the Malay 
Iilandf 342-356 



xii CONTENTS. 

CHAPTER XVIII. 

JAPAN AND FORMOSA. 

Japan : its Position and Physical Features. — Zoological Features of Japan. — Mam- 
malia. — Birds. — Birds Common to Great Britain and Japan. — Birds Pccnlior to 
Japan. — Japan Birds Recnrring in Distant Areas. — Formosa. — Physical Features 
of Formosa. — Animal Life of Formosa. — Mammalia. — Land Birds Peculiar to 
Formosa.— Formosan Birds Kecuning in India or Molnya. — Comparison of 
Faunas of Hainan, Formosa, and Japan. — General ICemarks on Recent Continen- 
tal Islands. Pages 357-37r> 

CHAPTER XIX. 

ANCIENT CONTINENTAL ISLANDS I THE MADAGASCAR GROUP. 

Remarks on Ancient Continental Islands. — Physical Features of Madagascar. — Bio- 
logical Features of Madngasciir. — Mammalia. — Reptiles. — Rehition of Madagascar 
to Africa. — Early History of Africa and Madagascar. — Anomalies of Distribution, 
and how to Explain them. — The Birds of Madagascar as Indicating a Supposed 
Lemurian Continent. — Submerged Islands between Madagascar and India. — Con- 
cluding Remarks on '* Lemuria." — The Mascarene Islands. — The Comoro Islands. 
— The Seychelles Archipelago. — Birds of the Seychelles. — Reptiles and Amphibia. 
— Fresh -water Fishes. — Land Shells. — Mauritius, Bourbon, and Rodriguez. — 
Birds. — Extinct Birds and their Probable Origin.— Reptiles. — Flora of Madagas- 
car and the Mascarene Islands. — Curious Relations of Mascarene Plants. — En- 
demic Genera of Mauritius and Seychelles. — Fragmentary Character of the Mas- 
carene Flora. — Flora of Madagascar Allied to that of South Africa. — Preponder- 
ance of Ferns in the Mascarene Flora. — Concluding Remarks on the Madagascar 
Group 370-412 

CnAPTER XX. 

ANOMALOUS ISLANDS I CELEBES. 

Anomalous Relations of Celebes. — Physical Features of the Island. — Zoological 
Character of the Islands around Celebes. — The Malnvan and Australian Banks. — 
Zoology of Celebes: Mammalia. — Probable Derivation of the Alainmals of Cele- 
bes. — Birds of Celebes. — Bird-types Peculiar to Celebes. — Celebes not strictly a 
Continental Island. — Peculiarities of the Insects of Celebes. — Himalayan Types of 
Birds and Butterflies in Celebes. — Peculiarities of Shape and Color of Celebesian 
Butterflies. — Concluding Remarks. — Appendix on the Birds of Celebes. . 413-433 

CHAPTER XXI. 

ANOMALOUS ISLANDS : NEW ZEALAND. 

Position and Physical Features of New Zealand. — Zoological Character of New Zea- 
land. — Mammalia. — Wingless Birds Living and Extinct. — Recent Existence of the 
Moa. — Post Changes of New Zealand Deduced from its Wingless Birds. — Birds 



CONTENTS. xiii 

and Reptiles of New Zealand. — Conclusions from the Peculiarities of the New Zen- 
land Fauna Pages 434-448 

CHAPTER XXII. 

THE FLORA OF NEW ZEALAND : ITS AFFINITIES AND PROBABLE ORIGIN. 

Relations of the New Zealand Flora to that of Australia.— General Features of the 
Australian Flora. — 'llie Floras of Southeastern and Southwestern Australia. — Geo- 
logical Explanation of the Differences of these two Floras. — ^The Origin of the Aus- 
tralian Element in the New Zealand Flora. — Tropical Character of the New Zea- 
land Flora Explained. — Species Common to New Zealand and Australia mostly 
Temperate Forms. — Why Easily Dispersed Plants have often Restricted Ranges. — 
Summary and Conclusion on the New Zealand Flora 449-468 

CHAPTER XXIIL 

ON THE ARCTIC ELEMENT IN SOUTH TEMPERATE FLORAS. 

European Species and Genera of Plants in the Southern Hemisphere. — Aggressive 
Power of the Scandinavian Flora. — Means by which Plants have Migrated from 
North to South. — Newly Moved Soil as Affording Temporary Stations to Migrat- 
ing Plants. — Elevation and Depression of the Snow-line as Aiding the Migration 
of Plants. — Changes of Climate Favorable to Migration. — The Migration from 
North to South has been long going on. — Geological Changes as Aiding Migra- 
tion. — Proofs of Migration by Way of the Andes. — ^Proofs of Migration by Way 
of the Himalayas and Southern Asia. — Proofs of Migration by Way of the African 
Highlands. — Supposed Connection of South Africa and Australia. — The Endemic 
Genera of Plants in New Zealand. — The Absence of Southern Types from the 
Northern Hemisphere. — Concluding Remarks on the New Zealand and South 
Temperate Floras 4C9-489 

CHAPTER XXIV. 

SUMMARY AND CONCLUSION. 

The Present Volume is the Development and Application of a Theory. — Statement 
of the Biological and Physical Causes of Dispersal. — Investigation of the Facts of 
Dispersal. — Of the Means of Dispersal. — Of Geographical Changes Affecting Dis- 
persal. — Of Climatal Changes Affecting Dispersal. — The Glacial Epoch and its 
Causes. — Alleged Ancient Glacial Epochs. — Warm Polar Climates and their Causes. 
— Conclusions as to Geological Climates. — How far Different from those of Mr. 
Croll. — Supposed Limitations of GreologicalTime. — Time Amply SuflScient both for 
Geological and Biological Development. — Insular Faunas and Floras. — The North 
Atlantic Islands. — The Galapagos. — St. Helena and the Sandwich Islands. — Great 
Britain as a Recent Continental Island. — Borneo and Java. — Japan and Formosa. 
— Madagascar as an Ancient Continental Island. — Celebes and New Zealand as 
Anomalous Islands. — ^The Flora of New Zealand and its Origin. — ^The European 
Element in the South Temperate Floras.— Concluding Remarks. 490-503 

IKDBX 607-522 



MAPS AND ILLUSTRATIONS. 



PAOB 

1. Map SnowiMO thb Distbidution of the True Jays Frontispiece. 

2. Maf Showixo the Zoological Beoions To/ace 30 

3. Map Showing the Distribution of Parvs Palustris, To face C2 

4. A Glacier with Moraines (From Sir C. Lyell's " Principles of Ge- 

ology"; 103 

5. Map of the Ancient Rhone Glacier (From Sir C. Ljell's '* Autiquity 

of Man") 105 

C. Diagram Showing the Effects of Ecckntricitt and Precession 

on Climate 121 

7. Diagram of Kccentricitt and Precession. . . 122 

8. Map Showing the Extent of the North and South Polar Ice... 131 

9. Diagram Showing Changes of Eccentricity During Three Mill- 

ion Years 1 63 

10. Outline Map of the Azores 235 

1 1. Map of Bermuda and the American Coast 250 

1 2. Section of Bermuda and Adjacent Sea-bottom 251 

13. Map of the Galapagos and Adjacent Coasts of South America.. 2C2 

14. Map of the Galapagos. 263 

15. Map of the South Atlantic, Showing Position of St. Helena.... 277 

16. Map of the Sandwich Islands 294 

17. Map of the North Pacific, with its Submerged Banks 295 

IS. Map Showing the Shallow Bank Connecting the British Isles 

WITH THE Continent 309 



xvi MAPS AND ILLUSTRATIONS. 

PAGB 

19. Map of Borneo and Java, Showing the Great Submarine Bank 

OF Southeastern Asia 343 

20. Map of Japan and Formosa 358 

21. Physical Sketch Map of Madagascar (From Nature) 378 

22. Map of Madagascar Group, Showing Depths of Sea 3£0 

23. Map of the Indian Ocean 389 

24. Map of Celebes and the Surrounding Islands 415 

25. Map Showing Depths of Sea around Australia and New Zea- 

land 435 

26. Map Showing the Probable Condition of Australia during the 

Cretaceous Epoch 458 



Part I. 

THE DISPERSAL OF OEGANISMS: ITS PHENOMENA 

LAWS, AND CAUSES 






• • • 
• • - 



ISLAND LIFE. 



CHAPTER I. 

INTRODUCTORY. 

Remnrknblo Contrnsts in Distribution of Animals. — Brituin and Jnpnn. — Australia 
and New Zealand. — Bali and Lombok. — Florida and Bahama Islands. — Brazil 
and Africa. — Borneo, Madagascar, and Celebes. — Problems in Distribution to bo 
Found in every Country. — Can be Solved only by the Combination of many Dis- 
tinct Lines of Inquiry, Biological and Physical. — Islands Offer the Best Subjects 
for ti)0 Study of Distribution. — Outline of tho Subjects to be Discussed in tho 
Present Volume. 

When an Englishman travels by the nearest sea-route from 
Great Britain to Northern Japan he passes by countries very 
unlike his own, both in aspect and natural productions. Tho 
sunny isles of tho Mediterranean, the sands and date-palms of 
Egypt, the arid rocks of Aden, the cocoa groves of Ceylon, tho 
tiger- haunted jungles of Malacca and Singapore, the fertile 
plains and volcanic peaks of Luzon, the forest-clad mountains 
of Formosa, and the bare hills of China, pass successively in re- 
view ; till after a circuitous voyage of thirteen thousand miles 
he finds himself at llakodadi in Japan, lie is now separated 
from his starting-point by the whole width of Europe and 
Northern Asia, by an almost endless succession of plains and 
mountains, arid deserts or icy plateaux, yet when he visits the 
interior of the country he sees so many familiar natural objects 
that ho can hardly help fancying he is close to his home. lie 
finds the woods and fields tenanted by tits, hedge-sparrows, 
wrens, wagtails, larks, redbreasts, thrushes, buntings, and house- 
sparrows, some absolutely identical with our own feathered 
friends, others so closely resembling them that it requires a 



•"•. 



• • 






• • • 



• • 



ISLAND LIFE. [Paut I. 



• •• • 



practisB^ ornithologist to tell the difference. If he is fond of 
ina^Ats JId notices many butterflies and a host of beetles which, 
ACnj^li on close examination they are found to be distinct from 
onfSy are yet of the same general aspect, and seem just what 
\Vniiglit be expected in any part of Europe. There are also of 
course many birds and insects which are quite new and peculiar, 
but these are by no means so numerous or conspicuous as to re- 
move the general impression of a wonderful resemblance be- 
tween the productions of such remote islands as Britain and 
Yesso. 

Now let an inhabitant of Australia sail to New Zealand, a dis- 
tance of less than thirteen hundred miles, and he will find him- 
self in a country whose productions are totally unlike those of 
liis own. Kangaroos and wombats there are none, the birds are 
almost all entirely new, insects are very scarce and quite unlike 
the handsome or strange Australian forms, while even the veg- 
etation is all changed, and no gum-tree, or wattle, or grass-tree 
meets the traveller's eye. 

But there are some more striking cases even than this, of the 
diversity of the productions of countries not far apart. In the 
Malay Archipelago there are two islands, named Bali and Lom- 
bok, each about as large as Corsica, and separated by a strait 
only fifteen miles wide at its narrowest part. Yet these islands 
differ far more from each other in their birds and quadrupeds 
than do England and Japan. The birds of the one are extreme- 
ly unlike those of the other, the difference being such as to strike 
even the most ordinary observer. Bali has red and green wood- 
peckers, barbets, weaver-birds, and black-and-white magpie-rob- 
ins, none of which are found in Lombok, where, however, we find 
screaming cockatoos and friar-birds, and the strange mound-build- 
ing megapodes, which arc all equally unknown in Bali. Many 
of the kingfishers, crow-shrikes, and other birds, though of the 
same general form, are of very distinct species; and though a 
considerable number of birds are the same in both islands, the 
difference is none the less remarkable — as proving that mere 
distance is one of the least important of the causes which have 
determined the likeness or unlikeness in the animals of different 
countries. 



Chap. I.] INTRODUCTORY. 6 

In the western heraispliere we find equally striking examples. 
The eastern United States possess very peculiar and interesting 
plants and animals, the vegetation becoming more luxuriant as 
we go south, but not altering in essential character, so that when 
we reach the southern extremity of Florida we still find our- 
selves in the midst of oaks, sumachs, magnolias, vines, and other 
characteristic forms of the temperate flora ; while the birds, in- 
sects, and land-shells are almost identical with those found far- 
ther north. But if we now cross over the narrow strait, about 
fifty miles wide, which separates Florida from the Bahama Isl- 
ands, we find ourselves in a totally different country, surrounded 
by a vegetation which is essentially tropical and generally iden- 
tical with that of Cuba. The change is most striking, because 
there is no difference of climate, of soil, or apparently of posi- 
tion, to account for it ; and when we find that the birds, the in- 
sects, and especially the land-shells are almost all West Indian, 
while the North American typ6s of plants and animals have al- 
most all completely disappeared, we shall be convinced that such 
differences and resemblances cannot be due to existing condi- 
tions, but must depend npon laws and causes to which mere 
proximity of position offers no clew. 

Hardly less uncertain and irregular are the effects of climate. 
Hot countries usually differ widely from cold ones in all their 
organic forms; but the difference is by no means constant, nor 
does it bear any proportion to difference of temperature. Be- 
tween frigid Canada and sub -tropical Florida there are less 
marked differences in the animal productions than between 
Florida and Cuba or Yucatan, so much more alike in climate 
and 80 much nearer together. So the differences between the 
birds and quadrupeds of temperate Tasmania and tropical North 
Australia are slight and unimportant as compared with the enor- 
mous differences we find when we pass from the latter country 
to equally tropical Java. If we compare corresponding portions 
of different continents, we find no indication that the almost 
perfect similarity of climate and general conditions has any ten- 
dency to produce similarity in the animal world. The equato- 
rial parts of Brazil and of the west coast of Africa are almost 
identical in climate and in luxuriance of vegetation, but their 



6 ISLAND LIFE. [Part I. 

animal life is totally diverse. In the former we liave tapirs, 
sloths, and prehensile-tailed monkeys ; in the latter, elephants, 
antelopes, and man-like apes ; while among birds, the toucans, 
chatterers, and humming-birds of Brazil are replaced by the 
plantain-eaters, bee-eaters, and sun-birds of Africa. Parts of 
South -temperate America, South Africa, and South Australia 
correspond closely in climate; yet the birds and quadrupeds of 
these three districts are as completely unlike each other as those 
of any parts of the world that can be named. 

If we visit the great islands of the globe, we lind that they 
present similar anomalies in their animal productions, for while 
some exactly resemble the nearest continents, others are widely 
different. Thus the quadrupeds, birds, and insects of Borneo 
correspond very closely to those of the Asiatic continent, while 
those of Madagascar are extremely unlike African forms, al- 
though the distance from the continent is less in the latter case 
than in the former. And if we compare the three great islands 
Sumatra, Borneo, and Celebes — lying, as it were, side by side in 
the same ocean — we find that the two former, although farthest 
apart, have almost identical productions, while the two latter, 
though closer together, are more unlike than Britain and Japan, 
situated in different oceans and separated by the largest of the 
great continents. 

These examples will illustrate the kind of questions it is the 
object of the present work to deal with. Every continent, ev- 
ery country, and every island on the globe offer similar problems 
of greater or less complexity and interest, and the time has now 
airived when their solution can be attempted with some prospect 
of success. Many years' study of this class of subjects has con- 
vinced me that there is no short and easy method of dealing 
with them ; because they arc, in their very nature, the visible 
outcome and residual product of the whole past history of the 
earth. If we take the organic productions of a small island, or 
of any very limited tract of country, such as a moderate-sized 
country parish, we have, in their relations and affinities — in the 
fact that they are there and others are not there, a problem which 
involves all the migrations of these species and their ancestral 
forms — all the vicissitudes of climate and all the changes of sea 



Chap. I.] INTRODUCTORY. 7 

and land which have affected those migratioils — the whole series 
of actions and reactions which have determined the preservation 
of some forms and the extinction of othere — in fact, the whole 
history of the earth, inorganic and organic, throughout a large 
portion of geological time. 

We shall perhaps better exhibit the scope and complexity of 
the subject, and "show that any intelligent study of it was almost 
impossible till quite recently, if we concisely enumerate the great 
mass of facts and the number of scientific theories or principles 
which are necessary for its elucidation. 

We require, then, in the first place, an adequate knowledge of 
the fauna and flora of the whole world, and even a detailed 
knowledge of many parts of it, including the islands of more 
special interest and their adjacent continents. This kind of 
knowledge is of very slow growth, and is still very imperfect ;* 
and in many cases it can never now be obtained, owing to the 
reckless destruction of forests, and with them of countless spe- 
cies of plants and animals. In the next place, we require a true 
and natural classification of animals and plants, so that we may 
know their real aflinities ; and it is only now that this is being 

* I cannot avoid here referring to the enormous waste of labor and money with 
comparatively scanty and unimportant results to natural history of most of the great 
scientific voyages of the various civilized governments during the present centui*}*. 
All these expeditions combined have done fur less than private collectors in making 
known the products of remote lands and islands. They have brought home fragmen- 
tary collections, made in widely scattered localities, and these have been usually do- 
scribed in huge folios, whose value is often in inverse proportion to their bulk and 
cost. The same species have been collected again and again, often described several 
times over under new names, and not unfrequcntly stated to be from places they 
never inhabited. The result of this wretched system is that the productions of some 
of the most frequently visited and most interesting islands on the globe are still very 
imperfectly known, while their native plants and animals are being yearly exterminat- 
ed ; and this is the case even with countries under the rule or protection of Euro- 
pean governments. Such are the Sandwich Islands, Tahiti, the Marquesas, the Phil- 
ippine Islands, and a host of smaller ones ; while Bourbon and Mauritius, St. Helena, 
and several others have only been adequately explored after an important portion of 
their productions has been destroyed by cultivation or the reckless introduction of 
goats and pigs. The employment in each of our possessions, and those of other Eu- 
ropean powers, of a resident naturalist at a very small annual expense, would have 
done more for the advancement of knowledge in this direction than all the expensive 
expeditions that have again and again circumnavigated the globe. 



8 ISLAND LIFE. [Part L 

generally arrived at. We further have to make use of the the- 
ory of " descent with modification " as the only possible key to 
the interpretation of the facts of distribution ; and this theory 
has only been generally accepted within the last twenty years. 
It is evident that, so long as the belief in " special creations " 
of each species prevailed, no explanation of tlie complex facts 
of distribution could be arrived at or even conceived ; for if each 
species was created where it is now found, no further inquiry 
can take us beyond that fact, and there is an end of the whole 
matter. Another important factor in our interpretation of the 
phenomena of distribution is a knowledge of the extinct forms 
that have inhabited each country during the tertiary and sec- 
ondary periods of geology. Xew facts of this kind are daily 
coming to light, but except as regards Europe, North America, 
and parts of India, they are extremely scanty ; and even in the 
best-known countries the record itself is often very defective 
and fragmentary. Yet we have already obtained remarkable 
evidence of the migrations of many animals and plants in past 
ages, throwing an often unexpected light on the actual distri- 
bution of many groups.* By this means alone can we obtain 
positive evidence of the past migrations of organisms ; and when, 
as too frequently is the case, this is altogether wanting, we have 
to trust to collateral evidence and more or less probable hypo- 
thetical explanations. Hardly less valuable is the evidence of 
stratigraphical geology ; for this often shows us what parts of a 
country have been submerged at certain epochs, and thus ena- 
bles us to prove that certain areas have been long isolated, and 
the fauna and flora allowed time for special development. Here, 
too, our knowledge is exceedingly imperfect, though the blanks 
upon the geological map of the world are yearly diminishing in 
extent. Lastly, as a most valuable supplement to geology, we 
require to know the exact depth and contour of the ocean-bed, 
since this affords an important clew to the former existence of 
now submerged lands, uniting islands to continents, or affording 
intermediate stations which have aided the migrations of many 

' The general facts of Palaeontology, as bearing on the migrations of animal 
groups, are summarized in my ** Geographical Distribution of Animals," Vol. L, 
Chapters VL, VH., and VIH.' 



Chap. I.J INTRODUCTORY. 9 

organisms. Tliis kind of information has only begun to be ob- 
tained during the last few years ; and it will be seen in the latter 
part of this volume that some of the most recent deep-sea sound- 
ings have affoi*ded a basis for an explanation of one of the most 
difficult and interesting questions in geographical biology — the 
origin of the fauna and flora of New Zealand. 

Such are the various classes of evidence that bear directly on 
the question of the distribution of organisms; but there are 
others of even a more fundamental character, and the impor- 
tance of which is only now beginning to be recognized by stu- 
dents of nature. These are, firstly, the wonderful alterations of 
climate which have occurred in the temperate and polar zones, 
as proved by the evidences of glaciation in the one and of luxu- 
riant vegetation in the other ; and, secondly, the theory of the 
permanence of existing continents and oceans. If glacial epochs 
in temperate lands and mild climates near the poles have, as now 
believed by men of eminence, occurred several times over in the 
past history of the earth, the effects of such great and repeated 
changes, both on the migration, modification, and extinction of 
species, must have been of overwhelming importance — of more 
importance, perhaps, than even the geological changes of sea and 
land. It is therefore necessary to consider the evidence for 
these climatal changes ; and then, by a critical examination of 
their possible causes, to ascertain whether they were isolated phe- 
nomena, were due to recurrent cosmical actions, or were the re- 
sult of a great system of terrestrial development. The latter is 
the conclusion we arrive at ; and this conclusion brings with it 
the conviction that, in the theory which accounts for both gla- 
cial epochs and warm polar climates, we have the key to explain 
and harmonize many of the most anomalous biological and geo- 
logical phenomena, and one which is especially valuable for the 
light it throws on the dispersal and existing distribution of or- 
ganisms. The other important theory, or rather corollary from 
the preceding theory — that of the permanence of oceans and the 
general stability of continents throughout all geological time — is 
as yet very imperfectly understood, and seems, in fact, to many 
persons in the nature of a paradox. The evidence for it, how- 
ever, appears to mo to be conclusive ; and it is certainly the 



10 ISLAND LIFE. [Pabt L 

raost fundamental question in regard to the subject we have to 
deal witli ; since, if we once admit that continents and oceans 
may have changed places over and over again (as many writei^s 
maintain), we lose all power of reasoning on the migrations of 
ancestral forms of life, and are at the mercy of every wild theo- 
rist who chooses to imagine the former existence of a now sub- 
merged continent to explain the existing distribution of a group 
of frogs or a genus of beetles. 

As already shown by the illustrative examples adduced in this 
chapter, some of the most remarkable and interesting facts in 
the distribution and affinities of organic forms are presented by 
islands in relation to each other and to the surrounding conti- 
nents. The study of the productions of the Galapagos — so pe- 
culiar, and yet so decidedly related to the American continent 
— appears to have had a powerful influence in determining the 
direction of Mr. Darwin's researches into the origin of species ; 
and every naturalist who studies them has always been struck 
by the unexpected relations or singular anomalies which are so 
often found to characterize the fauna and flora of islands. Yet 
their full importance in connection with the history of the earth 
and its inhabitants has hardly yet been recognized ; and it is in 
order to direct the attention of naturalists to this most promis- 
ing field of research that I restrict myself in this volume to an 
elucidation of some of the problems they present to us. By far 
the larger part of the islands of the globe are but portions of 
continents undergoing some of the various changes to which 
they are ever subject ; and the correlative statement, that every 
'7 '^ ' ESJ't ^^ ^^^^ continents have again and again passed through in- 
sular conditions, has not been sufficiently considered, but is, I 
believe, the statement of a great and most suggestive truth, and 
one which lies at the foundation of all accurate conception of 
the physical and organic changes which have resulted in the 
present state of the earth. 

The indications now given of the scope and purpose of the 
present volume render it evident that, before we can proceed 
to the discussion of the remarkable phenomena presented by 
insular faunas and floras, and the complex causes which have 
produced them, we must go through a series of preliminary 



Chap. I.] INTRODUCTORY. 11 

studies, adapted to give us a command of the more important 
facts and principles on wbicli the solution of such problems 
depends. The succeeding eight chapters will, therefore, be de- 
voted to the explanation of the mode of distribution, variation, 
modification, and dispersal of species and groups, illustrated by 
facts and examples; of the true nature of geological change 
as affecting continents and islands; of changes of climate, their 
nature, causes, and effects ; of the duration of geological time 
and the rate of organic development. 



12 ISLAND LIFE. [Part L 



CHAPTER 11. 

THE ELEMENTARY FACTS OF DISTRIBUTION. 

Importance of LocaJity ns an Essential Character of Species. — Areas of Distribution. 
— Extent and Limitations of Specific Areas. — Specific Range of Bird:?. — Generic 
Areas. — Separate and Overlapping Areas. — The Species of Tits as Illustrating 
Areas of Distribution. — The Distribution of the Species of Jays. — Discontinuous 
Generic Areas. — Peculiarities of Generic and Family Distribution. — General Feat- 
ures of Overlapping and Discontinuous Areas. — Restricted Areas of Families. — 
The Distribution of Orders. 

So long as it was believed that the several species of animals 
and plants were "special creations," and had been formed ex- 
pressly to inhabit the countries in which they are now found, 
their habitat was an ultimate fact which required no explana- 
tion. It was assumed that every animal was exactly adapted 
to the climate and surroundings amid which it lived, and that 
the only, or, at all events, the chief, reason why it did not in- 
habit another country was, that the climate or general condi- 
tions of that country were not suitable to it, but in what the 
unsuitability consisted wo could rarely hope to discover. Hence 
the exact locality of any species was not thought of much im- 
portance from a scientific point of view, and the idea that any- 
thing could be learned by a comparative study of different floras 
and faunas never entered the minds of the older naturalists. 

But so soon as the theory of evolution came to be generally 
adopted, and it was seen that each animal could only have come 
into existence in some area where ancestral forms closely allied 
to it already lived, a real and important relation was established 
between an animal and its native countr}*, and a new set of 
problems at once sprang into existence. From the old point of 
view, the diversities of animal life in the separate continents, 
even where physical conditions were almost identical, was the 
fact that excited astonishment; but seen by the light of the 



chap.il] the elementary facts of distribution. 13 

evolution theory, it is the resemhlances rather than the diversi- 
ties in these distant continents and islands that are most difficult 
to explain. It thus comes to be admitted that a knowledge of 
the exact area occupied by a species or a group is a real portion 
of its natural history, of as much importance as its habits, its 
structure, or its affinities ; and that we can never arrive at any 
trustworthy conclusions as to how the present state of the or- 
ganic world was brought about until we have ascertained with 
some accuracy the general laws of the distribution of living 
things over the earth's surface. 

Areas of Distribution, — Every species of animal has a certain 
area of distribution to which, as a rule, it is permanently con- 
fined, althougli, no doubt, the limits of its range fluctuate some- 
what from year to year, and in some exceptional cases may be 
considerably altered in a few years or centuries. Each species 
is moreover usually limited to one continuous area, over the 
whole of which it is more or less frequently to be met with ; 
but there are many partial exceptions to this rule. Some ani- 
mals are so adapted to certain kinds of country — as to forests 
or marshes, mountains or deserts — that they cannot live long 
elsewhere. These may be found scattered over a wide area in 
suitable spots only, but can hardly on that account be said to 
liave several distinct areas of distribution. As an example, we 
may name the chamois, which lives only on high mountains, 
but is found in the Pyrenees, the Alps, the Carpathians, in 
some of the Greek mountains and the Caucasus. The variable 
hare is another and more remarkable case, being found all over 
Northern Europe and Asia, beyond lat. 55°, and also in Scot- 
land and Ireland. In Central Europe it is unknown till we come 
to the Alps, the Pyrenees, and the Caucasus, where it again ap- 
pears. This is one of the best cases known of the discontinuous 
distribution of a species^ there being a gap of about a thousand 
miles between its southern limits in Eussia and its reappearance 
in the Alps. There are, of course, numerous instances in which 
species occur in two or more islands, or in an island and con- 
tinent, and are thus rendered discontinuous by the sea, but these 
involve questions of changes in sea and land which we shall 
have to consider further on. Other cases are believed to exist 



14 ISLAND LIFE. [Pabt L 

of still wider separation of a species, as with the marsh titmice 
and the reed buntings of Europe and Japan, where similar forms 
are found in the extreme localities, while a distinct variety, race, 
or sub-species inhabits the intervening district. 

Extent and Limitations of Specific Areas, — Leaving for the 
present these cases of want of continuity in a species, we find 
the most wide diflEerence between the extent of country occu- 
pied, varying, in fact, from a few square miles to almost the en- 
tire land surface of the globe. Among the mammalia, however, 
the same species seldom inhabits both the old and new worlds, 
unless they are strictly arctic animals, as the reindeer, elk, and 
arctic fox, the glutton, the ermine, and some others. The com- 
mon wolf of Europe and Northern Asia is thought by many 
naturalists to be identical wuth the variously colored wolves of 
North America extending from the Arctic Ocean to Mexico, in 
which case this will have, perhaps, the widest range of any spe- 
cies of mammal. Little doubt exists as to the identity of the 
brown bears and the beavers of Europe and North America ; but 
all these species range up to the Arctic circle, and there is no 
example of a mammal universally admitted to bo identical yet 
confined to the temperate zones of the two hemispheres. Among 
the undisputed species of mammalia, the leopard has an enor- 
mous range, extending all over Africa and South Asia to Bor- 
neo and the east of China, and thus having probably the widest 
range of any known mammal. The winged mammalia have 
not usually very wide ranges, there being only one bat common 
to the Old and New Worlds. This is a British species, Vespe- 
rugo serotinus^ which is found over the larger part of North 
America, Europe, and Asia, as far as Pckin, and even extends 
into tropical Africa, thus rivalling the leopard and the wolf in 
the extent of country it occupies. 

Of very restricted ranges there are many examples, but some 
of these are subject to doubts as to the distinctness of the spe- 
cies or as to its geogmphical limits being really known. In 
Europe we have a distinct species of ibex {Capra Pyrenaica) 
confined to the Pyrenean mountains, while the true marmot is re- 
stricted to the Alpine range. More remarkable is the Pyrenean 
water-mole {Mygale Pijrenaica\ a curious small insectivorous 



Chap. II.] THE ELEMENTARY FACTS OF DISTIUBUTION. 15 

animal found only in a few places in the northern valleys of tho 
PjTcnees. In islands there are many cases of undoubted re- 
striction of species to a small area, but these involve a different 
question from the range of species on continents where there 
is no apparent obstacle to their wider extension. 

Specific Range of Birds. — Among birds we find instances of 
much wider range of species, which is only what might be ex- 
pected considering their powers of flight ; but, what is very 
curious, we also find more striking (though perhaps not more 
frequent) examples of extreme limitation of range among birds 
than among mammals. Of the former phenomenon perhaps 
the most remarkable case is that afforded by the osprey, or fish- 
ing-hawk, which ranges over the greater portion of all the con- 
tinents, as far as Bmzil, South Africa, the Malay Islands, and 
Tasmania. The barn-owl {Strix fiammed) has nearly as wide a 
range, but in this case there is more diversity of opinion as 
to the specific difference of many of the forms inhabiting re- 
mote countries, some of which seem undoubtedly to be distinct. 
Among passerine birds the raven lias probably the widest range, 
extending from the Arctic regions to Texas and New Mexico in 
America, and to North India and Lake Baikal in Asia; while 
the little northern willow-wren {PhyUoscopus horealis) ranges 
from Norway across Asia to Alaska, and southward to Ceylon, 
China, Borneo, and Timor. 

Of very restricted continental ranges the best examples in 
Europe are the little blue magpie {Cyanopica Cooki) confined to 
the central portions of the Spanish peninsula ; and the Italian 
sparrow found only in Italy and Corsica. In Asia, Palestine 
affords some examples of birds of very restricted range — a beau- 
tiful sun-bird {Nectarinea osea\ a peculiar starling {Aniydrus 
Trisiramii)^ and some others, being almost or quite confined to 
the warmer portions of the valley of the Jordan. In the Him- 
alayas there are numbers of birds which have very restricted 
ranges ; but those of the Neilgherries are perhaps better known, 
several species of laughing thrushes and other birds being found 
only on the summits of these mountains. The most wonder- 
fully restricted ranges are, however, to be found among the 
humming-birds of tropical America. The great volcanic peaks 



16 ISLAND LIFE. [Part L 

of Cliimborazo and Pichincha have each a peculiar species of 
humming-bird confined to a belt just below the limits of per- 
petual snow, while the extinct volcano of Chiriqui, in Veragua, 
has a species confined to its wooded crater. One of the most 
strange and beautiful of the humming-birds {Loddigesia mira- 
hilis) was obtained once only, more than forty years ago, near 
Chachapoyas, in the Andes of Northern Peru ; and though Mr. 
Gould lias sent many drawings of the bird to people visiting 
the district, and has for many years offered a high reward for 
a specimen, no other has ever been seen I * 

The above details will sufficiently explain what is meant by 
the "specific area" or range of a species. Tlie very wide and 
very narrow ranges are exceptional, the great majority of spe- 
cies both of mammals and birds ranging over moderately wide 
areas, which present no striking contrasts in climate and physical 
conditions. Thus a large proportion of European birds range 
over the whole continent in an east and west direction, but con- 
siderable numbers are restricted either to the northern or the 
southern half. In Africa some species range over all the conti- 
nent south of the desert, while large numbers are restricted to 
the equatorial forests, or to the upland plains. In North Amer- 
ica, if we exclude the tropical and the arctic portions, a consider- 
able number of species range over all the temperate parts of the 
continent, w^hile still more are restricted to the east, the centre, 
or the west, respectively. 

Generic Areas, — Having thus obtained a tolerably clear idea 
of the main facts as to the distribution of isolated species, let 
us now consider those collections of closely allied species termed 
genera. What a genus is will be sufficiently understood by a 
few illustrations. All the different kinds of dogs, jackals, and 
wolves belong to the dog genus, Canis; the tiger, lion, leopard, 
jaguar, and the wild-cats, to the cat genus, Felis; the blackbird, 
song- thrush, missel -thrush, fieldfare, and many others, to the 
thrush genus, Turdus; the crow, rook, raven, and jackdaw, to 
the crow genus, Corvus; but the magpie belongs to another, 

' Since these lines were written, the report comes tlmt fresh specimens 
hnve been found in the same locality. 



Chap. II.] THE ELEMENTARY FACTS OF DISTRIBUTION. 17 

though closely allied genus, Pica, distinguished by the different 
form and proportions of its wings and tail from all the species 
of the crow genus. The number of species in a genus varies 
greatly from one up to several hundreds. The giraffe, the glut- 
ton, the walrus, the bearded reedling, the secretary-bird, and 
many others, have no close allies, and each forms a genus by 
itself. The beaver genus, Castor, and the camel genus, Camelns, 
each consist of two species. On the other hand, the deer genus, 
Cervus, has forty species ; the mouse and rat genus, Mus, more 
than a hundred species ; and there is about the same number of 
the thrush genus; while among the lower classes of animals 
genera are- often very extensive, the fine genus Papilio, or swal- 
low-tailed butterflies, containing more than four hundred spe- 
cies; and Cicindela, which includes our native tiger beetles, has 
about the same number. Many genera of shells are very ex- 
tensive, and one of them — tlie genus Ilelix, including the com- 
monest snails, and ranging all over the world — is probably the 
most extensive in the animal kingdom, numbering about two 
thousand described species. 

Separate and Overlapping Areas. — The species of a genus are 
distributed in two ways. Either they occupy distinct areas which 
do not touch each other and are sometimes widely separated, or 
they touch and occasionally overlap each other, each species oc- 
cupying an area of its own which rarely coincides exactly with 
that of any other species of the same genus. In some eases, 
-when a river, a mountain-chain, or a change of conditions, as from 
pasture to desert or forest, determines the range of species, the 
areas of two species of the same genus may just meet, one be- 
ginning where the other ends ; but this is comparatively rare. 
It occurs, however, in the Amazon valley, where several species 
of monkeys, birds, and insects come up to the south bank 
of the river, but do not pass it, while allied species come to the 
north bank, which in like manner forms their boundary. As 
examples we may mention that one of the Saki monkeys {Piihe- 
cia mona^chus?) comes up to the south bank of the Upper Ama- 
zon, while immediately we cross over to the north bank we find 
another species {Pithecia rufiharhata ?), Among birds we have 
the green jacamar {Galhda viriJis) abundant on the north bank 

2 



18 ISLAND LIFE. [Part L 

of the Lower Amazon, while on the south bank we have two 
allied species {GaUbxda 7'ufoviridis and G. cj/aneicoUis); and 
among insects we have at Sautarem, on the south bank of the 
Amazon, the beautiful blue butterfly CaUithea sapphira^ while 
almost opposite to it, at Monte-alegre, an allied species, CaUithea 
Leprieuri^ is alone found. Perhaps the most interesting and 
best-known case of a series of allied species whose ranges are 
separate but conterminous is that of the beautiful South Amer- 
ican wading birds, called trun)peters, and forming the genus 
Psophia. There are five species, all found in the Amazon valley, 
but each limited to a well-marked district bounded by great 
rivers. On the north bank of the x\mazon there are two species, 
one in its lower valley extending up to the Kio Negro, and the 
other in the central part of the valley beyond that river; while 
to the south of the Amazon there are three, one above the Ma- 
deira, one below it, and a third near Para, probably separated 
from the last by the Tocantins River. 

Overlapping areas among the species oi a genus is a more 
common phenomenon, and is almost universal where these spe- 
cies are numerous in the same continent. It is, however, ex- 
ceedingly irregular, so that we often find one species extending 
over a considerable portion of the area occupied by the genus, 
and including the entire areas of some of the other species. So 
little has been done to work out accurately the limits of species 
that it is very difficult to give examples. One of the best is to 
be found in the genus Dendroeca, a group of American wood- 
warblers. These little birds all migrate in the winter into the 
tropical regions, but in the summer they come north, each hav- 
ing its particular range. Thus, D. Domhiica comes as far as 
South Caroliuii, D, cchrulea to Virginia, D. discolor to Southern 
Maine and Canada; four other species go farther north in Ca- 
nada, while five more extend to the borders of the Arctic zone. 

The /Species of llts as Illustrating Areas of Distribution, — In 
our own hemisphere the overlapping of allied species may be 
well illustrated by the various kinds of titmice, several of which 
are among our best-known Plnglish birds. The great titmouse 
{Panis major) has the widest range of all, extending from the 
Arctic circle to Algeria, Palestine, and Persia, and from Ireland 



CujLP.ll.] THE ELExMENTABY FACTS OF DISTRIBUTION. 19 

riglit across Siberia to the Ochotsk Sea, probably following tlio 
great northern forest belt. It does not extend into China and 
Japan, where distinct species are found. Next in extent of 
range is the coal tit {Pants ater\ which inhabits all Europe, 
from the Mediterranean to about 64° N. latitude ; in Asia Minor 
to the Lebanon and Caucasus ; and across Siberia to Amoorland. 
The marsh tit {Parua palitstris) inhabits temperate and south 
Europe from 61° N. latitude in Norway to Poland and South- 
west Russia, and in the south from Spain to Asia Minor. Close- 
ly allied to this — of which it is probably only a variety or sub- 
species — is the northern marsh tit {Parus horeaUs)^ which over- 
laps the last in Norway and Sweden, and also in South Russia 
and the Alps, but extends farther north into Lapland and North 
Russia, and thence probably in a southeasterly direction across 
Central Asia to North China. Yet another closely allied species 
(Parus Camtschatkensis) ranges from Northeastern Russia across 
Northern Siberia to Lake Baikal and to Hakodadi in Japan, thus 
overlapping Parus horealis in the western portion of its area. 
Our little favorite, the blue tit {Parus cosruleus)^ ranges over all 
Europe from the Arctic circle to the Mediterranean, and on to 
Asia Minor and Persia, but does not seem to pass beyond the 
Ural Mountains. Its lovely eastern ally, the azure tit {Parus 
cyaneus\ overlaps the range of P. eoeruleus in Western Europe 
as far as St, Petersburg and Austria, rarely straggling to Den- 
mark, while it stretches all across Central Asia between the lati- 
tudes 35° and 56° N. as far as the Amoor valley. Besides these 
wide-ranging species, there are several others which are more re- 
stricted. Panis TeneriffcBj a beautiful dark-blue form of our 
blue tit, inhabits Northwest Africa and the Canaries ; Parus Le- 
douci^ closely allied to our coal tit, is found only in Algeria ; 
Parus Ivguhris^ allied to the marsh tit, is confined to Southeast 
Europe and Asia Minor, from Hungary and South Russia to Pal- 
estine ; and Parus cinctuSy another allied form, is confined to 
the extreme north in Lapland, Finland, and perhaps Northern 
Russia and Siberia. Another beautiful little bird, the crested 
titmouse {Parus crisiatus\ is sometimes placed in a separate ge- 
nns. It inhabits nearly all Central and South Europe, wherever 
there are pine forests, from 64° N. latitude to Austria and North 



20 ISLAND LIFE. [Part I. 

Italy, and in the west to Spain and Gibraltar, while in the east 
it does not pass the Urals and the Caucasus range. Its nearest 
allies are in the high Himalayas. 

These are all the European tits, but there are many others in- 
habiting Asia, Africa, and North America ; so that the genus 
Parus has a very 'wide range, in Asia to Ceylon and the Malay 
Islands, in Africa to the Cape, and in North America to the 
higlilands of Mexico. 

The Dutributioii of the Specie of Jays. — Owing to the very 
wide range of several of the tits, the uncertainty of the specific 
distinction of others, and the difficulty in many cases of ascer- 
taining their actual distribution, it has not been found practica- 
ble to illustrate this genus by means of a map. For this pur- 
pose we have chosen the genus Garrulus, or the jays, in which 
the species are less numerous, the specific areas less extensive, 
and the species generally better defined ; while, being large and 
handsome birds, they are sure to have been collected, or at least 
noticed, wherever they occur. There are, so far as yet known, 
twelve species of true jays, occupying an area extending from 
Western Europe to Eastern Asia and Japan, and nowhere pass- 
ing the Arctic circle to the north, or the Tropic of Cancer to the 
south, so that they constitute one of the most typical of the Pa- 
laearctic' genera. The following are the species, beginning with 
the most westerly and proceeding towards the east. The num- 
bers prefixed to each species correspond to those on the colored 
map which forms the frontispiece to this volume. 

1. Garrulus glundarius, the common jay, inhabits the Brit- 
ish Isles and all Europe except the extreme north, extending 
also into North Africa, where it has been observed in many 
parts of Algeria. It occurs near Constantinople, but apparently 
not in Asia Minor, and in Kussia up to, but not beyond, the 
Urals. The jays, being woodland birds, are not found in open 
plains or barren nplands, and their distribution is hence by no 
means uniform within the area they actually occupy. 

2. Garrulus cetmcalls, the Algerian jay, is a very distinct 



* The Pnlflcarctic region includes tempcnitc Asia and Europe, ns will be explained 
the next choDter. 



in the next chapter 



CiiAP.IL] THE ELEMENTARY FACTS OF DISTRIBUTION. 21 

species inhabiting a limited area in North Africa, and found in 
some places along with the common species. 

3. Garrulus Krynicki^ the black-headed jay, is closely allied 
to the common species, but quite distinct, inhabiting a compara- 
tively small area in Southeastern Europe and Western Asia. 

4. Garrulus atricapiUus^ the Syrian jay, is very closely al- 
lied to the last, and inhabits an adjoining area in Syria, Pales- 
tine, and Southern Persia. 

5. GarrviLus hyrcanus^ the Persian jay, is a small species al- 
lied to our jay, and only known from tlio Elburz Mountains in 
the north of Persia. 

6. Gan^ulus Brandti^ Brandt's jay, is a very distinct species, 
having an extensive range across Asia from the Ural Mountains 
to North China, Mandchuria, and the northern island of Japan, 
and also crossing the Urals into Eussia, where it has been found 
as far west as Kazan in districts where the common jay also 
occurs. 

7. Garrulus lanc€ol<itu8^ the black-throated jay, is a very dis- 
tinct form known only from the Northwesteni Himalayas and 
Nepal, common about Simla, and extending into Cashmere be- 
yond the range of the next species. 

8. Garrulus hispecularis^ the Himalayan jay, is also very dis- 
tinct, having the head colored like the back, and not striped as 
in all tlie western species. It inhabits the Himalayas east of 
Cashmere, but is more abundant in the western tlian the eastern 
division, though, according to the Abbe David, it reaches Mou- 
pin in East Thibet. 

9. Garrulus Sinensis^ the Chinese jay, is very closely allied 
to the Himalayan, of which it is sometimes classed as a sub-spe- 
cies. It seems to be found in all tlie southern mountains of 
China, from Foochow on the east to Sze-chuen and East Thibet 
on the west, as it is recorded from Moupin by the Abbe David 
as well as the Himalayan bird — a tolerable proof that it is a dis- 
tinct form. 

10. Garrulus taivanus^ the Formosan jay, is a very close ally 
of the preceding, confined to the island of Formosa. 

11. Garrulus JaponicuSj the Japanese jay, is very closely 
allied to our common British species, being somewhat smaller 



22 ISLAND LIFE. [Pjlrt L 

and less brightly colored, and with black orbits ; yet these are 
the most widely separated species of the genus. 

12. Garrvliis Lidthi. — This is the handsomest of all the jays, 
the head, neck, and wings being azure blue. Its locality was 
long doubtful, but it has now been ascertained to inhabit Japan, 
where it is evidently very rare, its exact habitat being still un- 
known. 

In the accompanying map (see frontispiece) we have laid down 
the distribution of each species so far as it can be ascertained 
from the works of Sharpe and Dresser for Europe, Jerdon for 
India, Swinhoe for China, and Messrs. Blakiston and Pryer for 
Japan. There is, however, much uncertainty in many places, and 
gaps have to be filled up conjecturally, while such a large part 
of Asia is still very imperfectly explored that considerable mod- 
ifications may have to be made when the country becomes more 
accurately known. But though details may be modified, we can 
hardly suppose that the great features of the several specific 
areas, or their relations to each other, will be much affected ; and 
these are what we have chiefly to consider as bearing on the 
questions here discussed. 

The first thing that strikes us on looking at the map is the 
small amount of overlapping of the several areas, and the isola- 
tion of many of the species ; while the next most striking feat- 
ure is the manner in which the Asiatic species almost surround 
a vast area in which no jays are found. The only species with 
large areas are the European 6r. glandarius and the Asiatic G, 
Brandti, The former has three species overlapping it — in Al- 
geria, in Southeastern and in Northeastern Europe respectively. 
The Syrian jay (No. 4) is not known to occur anywhere with the 
black-headed jay (No. 3), and perhaps the two areas do not meet. 
The Persian jay (No. 5) is quite isolated. The Himalayan and 
Chinese jays (Nos. 7, 8, and 9) form a group which arc isolated 
from the rest of the genus; while the Japanese jay (No. 11) is 
also completely isolated as regards the European jays, to which 
alone it is closely allied. These peculiarities of distribution are 
no doubt in part dependent on the habits of the jays, which live 
only in well-wooded districts, among deciduous trees, and are es- 
sentially non-migratory in their habits, though sometimes moving 



Chap.it.] the elementary facts of DISTKICUTION. 23 

southward in winter. This will explain their absence from the 
vast desert area of Central Asia, but it will not account for the 
gap between the North and South Chinese species, nor for the 
absence of jays from the wooded hills of Turkestan, where Mr. 
N. A. Severtzoff collected assiduously, obtaining 384 species of 
birds, but no jay. These peculiarities, and the fact that jays are 
never very abundant anywhere, seem to indicate that the genus 
is now a decaying one, and that it has at no very distant epoch 
occupied a larger and more continuous area, such as that of the 
genus Parus at the present day. 

Discontinuous Generic Areas, — It is not very easy to find good 
examples of genera whose species occupy two or more quite dis- 
connected areas, for though such cases may not be rare, we are 
seldom in a position to mark out the limits of the several species 
with sufficient accuracy. The best and most remarkable case 
among European birds is that of the blue magpies, forming the 
genus Cyanopica. One species ((7. Coohi) is confined (as already 
stated) to the wooded and mountainous districts of Spain and 
Portugal, while the only other species of the genus (C. cyanus) 
is found far away in Northeastern Asia and Japan, so that the 
two species are separated by about 5000 miles of continuous 
land. Another case is that of the curious little water-moles form- 
ing the genus Mygale, one species, M. Muscovitica, being found 
only on the banks of the Volga and Don in Southeastern Rus- 
sia, while the other, M, Pyrenaica^ is confined to streams on the 
northern side of the Pyrenees. In tropical America there are 
four different kinds of bell-birds belonging to the genus Chas- 
morhynchns, each of which appeare to inhabit a restricted area 
completely separated from the others. The most northerly is 
C tricamncxdatus of Costa Kica and Veragua, a brown bird with 
a white head and three long caruncles growing upwards at the 
base of the beak. Next comes C. variegatus^ in Venezuela, a 
white bird with a brown head and numerous caruncles on the 
throat, perhaps conterminous with the last ; in Guiana, extending 
to near the month of the Kio Negro, we have C. 7iiveus^ the bell- 
bird described by Waterton, which is pure white, with a single 
long fleshy caruncle at the base of the beak ; the last species, C. 
nndicoUisy inhabits Southeast Brazil, and is also white, but with 



24: ISLAND LIFE. [Part I. 

black stripes over the eyes, and with a naked throat. Tliese birds 
are about the size of thrushes, and are all remarkable for their 
loud-ringing notes like a bell or a blow on an anvil, as well as 
for their peculiar colors. They are therefore known to the na- 
tive Indians wherever they exist, and we may be the more sure 
that they do not spread over the intervening areas where they 
have never been found, and where the natives know nothing of 
them. 

A good example of isolated species of a group nearer home is 
afforded by the snow-partridges of the genus Tetraogallus. One 
species inhabits the Caucasus range and nowhere else, keeping to 
the higher slopes from 6000 to 11,000 feet above the sea, and 
accompanying the ibex in its wanderings, as both feed on the 
same plants. Another has a wider range in Asia Minor and 
Persia from the Taurus Mountains to the southeast corner of 
the Caspian Sea ; a third species inhabits the Western Hima- 
layas, between the forests and perpetual snow, extending east- 
ward to Nepal, while a fourth is found on the north side of the 
mountains in Thibet, and the mnges of these two perhaps over- 
lap; the last species inhabits the Altai Mountains, and like the 
two first appears to be completely separated from all its allies. 

There are some few still more extraordinarv cases in which 
the species of one genus are separated in remote continents or 
islands. The most striking of these is that of the tapirs, forming 
the genus Tapirus, of which there are two or three species in 
South America, and one very distinct species in Malacca and 
Borneo, separated by nearly half the circumference of the globe. 
Another example among quadrupeds is a peculiar genus of moles 
named Urotrichus, of which one species inhabits Japan and the 
other British Columbia. The cuckoo-like honey-guides, forming 
the genus Indicator, are tolerably abundant in tropical Africa, 
but there arc two outlying species, one in the Eastern Himalaya 
Mountains, the other in Borneo, both very rare, and quite re- 
cently an allied species has been found in the Malay peninsula. 
The beautiful blue and green thrush -tits, forming the genus 
Cochoa, have two species in the Eastern Himalayas, while the 
third is confined to Java; the curious genus Eupetes, supposed 
to be allied to the dippers, has two species in Sumatra, and the 



Chap. II.] THE ELEMENTARY FACTS OF DISTRIBUTION. 25 

other species two thousand miles distant in New Guinea; lastly, 
the lovely ground-thrushes of the genus Pitta range from Hin- 
dostan to Australia, while a single species, far removed from all 
its near allies, inhabits West Africa. 

Peculiarities of Generic and Family Distribution. — The ex- 
amples now given sufficiently illustrate the mode in which the 
several species of a genus are distributed. We have next to 
consider genera as the component parts of families, and families 
of orders, from the same point of view. 

All the phenomena presented by the species of a genus are 
reproduced by the genera of a family, and often in a more 
marked degree. Owing, however, to the extreme restriction of 
genera by modern naturalists, there are not many among the 
higher animals that have a world-wide distribution. Among 
the mammalia there is no such thing as a truly cosmopolitan 
genus. This is owing to the absence of all the higher orders ex- 
cept the mice from Australia, while the genus Mus, which oc- 
curs there, is represented by a distinct group, Hesperomys, in 
America. If, however, we consider the Australian dingo as a 
native animal, we might class the genus Canis as cosmopolite, 
but the wild dogs of South America are now formed into sep- 
arate genera by some naturalists. Many genera, however, range 
over three or more continents, as Felis (the cat genus), absent 
only from Australia ; Ursus (the bear genus), absent from Aus- 
tralia and tropical Africa ; Cervus (the deer genus), with nearly 
the same range; and Scinrus (the squirrel genus), found in all 
the continents but Australia. Among birds, Turdus, the thrush, 
and Hirundo, the swallow genus, are the only perching birds 
which are truly cosmopolites; but there are many genera of 
hawks, owls, wading and swimming birds which have a world- 
wide range. 

As a great many genera consist of single species, there is no 
lack of cases of great restriction, such as the curious lemur called 
the " potto," which is found only at Sierra Leone, and forms 
the genus Perodicticus ; the true chinchillas, found only in the 
Andes of Peru and Chili south of 9° S. lat. and between 8000 
and 12,000 feet elevation ; several genera of finches, each con- 
fined to limited portions of the higher Himalayas ; the blood- 



ISLAND LIFE. 



CPaht I. 



plicasaiits (Ithaginis), found only above 10,000 feet from Nepal 
to East Thibet ; the bald-licaded starling of the Philippine Isl- 
ands, the lyre-birds of East Australia, and a host of others. 

It ia among the different genera of the eanie family that we 
meet with the moat Btriking examplea of diacontiuuity, although 
these genera are often as nnmistakably allied as are the Epecies 
of A genus ; and it is these cnecs that furnish the most intereat- 
iug problems to the student of distribution. We must, there- 
fore, consider them somewhat more fully. 

Among mammalia the most remarkable of these divided fam- 
ilies is that of the camels, of which one genus. Camel ue, the trne 
eamele, coinpriBing the camel and dromedary, is confined to 
Asia, while the other, Auchenia, comprising the llamas and 
alpacas, is found only in the high Andes and in the plains of 
temperate South Ameriea, Not only wro these two genera sep- 
arated by the Atlantic and by the greater part of the land of 
two continents, but one is eontined to the Northern and the 
other to the Sontheru Hemisphere. The next case, though not 
so well known, is equally remarkable; it is that of the Ccnteti- 
tise, a family of small insectivorous animals, which are wholly 
confined to Madagascar and the large West ludian islands Cubiv 
and Ilayti, the former containing five genera and the latter a 
single genua with a species in each island. Here again we have 
tho whole continent of Africa as well as the Atlantic Ocean sep- 
arating allied genera. Two families of rat like animals, Octo- 
dontidni and Echimyidse, are also divided by the Atlantic, Both 
arc mainly South American, but the former has two genera in 
North and East Africa, and the latter also two in South and 
West Africa. Two other familiea of mammalia, thongh confined 
to the Eaeteni Hemisphere, aro yet markedly discontinuous. 
The Tragiilidai are small deer-like animals, known as chevrotains 
or mousu-decr, abundant in India and the larger Malay islands, 
and forming the genus Traguhts; while another genns, Hyo- 
moschiis, is confined to West Afnea. The other family ia the 
Simiidte or anthropoid apes, in which we have the gorilla and 
chimpanzee confined to West and Central Africa, M'hile the 
allied oranga are found only in tho islands of Sumatra and 
Borneo, the two groups being separated by a greiiter space 



chap.il] the elementary facts of distribution. 27 

than the Echimyidae and other rodents of Africa and South 
America. 

Among birds and reptiles we have several families, which, 
from being found only within the tropics of Asia, Africa, and 
America, have been termed tropicopolitan groups. The Mega- 
Isemidae, or barbets, are gayly colored fruit-eating birds, almost 
equally abundant in tropical Asia and Africa, but less plentiful 
in America, where they probably suffer from the competition 
of the larger sized toucans. The genera of each country are 
distinct, but all are closely allied, the family being a very nat- 
ural one. The trogons form a family of very gorgeously col- 
ored and remarkable insect-eating birds very abundant in trop- 
ical America, less so in Asia, and with a single genus of two 
species in Africa. 

Among reptiles we have two families of snakes — the Den- 
dropliidse, or tree-snakes, and the Dryiophidse, or green whip- 
snakes — which are also found in the three tropical regions of 
Asia, Africa, and America, but in these cases even some of the 
genera are common to Asia and Africa, or to Africa and Amer- 
ica. The lizards forming the small family I^pidosternidae are 
divided between tropical Africa and South America, while 
even the peculiarly American family of the iguanas is repre- 
sented by two genera in Madagascar. Passing on to the Am- 
phibians, the worm-like Cseciliadae are tropicopolitan, as are also 
the toads of the family Phryniscidse. Insects also furnish some 
analogous cases, three genera of Cicindelidse (Pogonostoraa, Cte- 
nostoma, and Peridexia), showing a decided connection between 
this family in South America and Madagascar ; while the beau- 
tiful genus of diurnal moths, Urania, is confined to the same 
two countries. A somewhat similar but better-known illustra- 
tion is afforded by the two genera of ostriches, one confined to 
Africa and Arabia, the other to the plains of temperate South 
America. 

General Features of Overlapping and Discontinuous Areas, — 
These numerous examples of discontinuous genera and families 
form an important section of the facts of animal dispei-sal which 
any true theory must satisfactorily account for. In greater or 
less prominence they are to be found all over the world, and in 



28 ISLAND LIFE. [Part L 

every group of animals, and they grade imperceptibly into 
those eases of conterminous and overlapping areas which we 
have seen to prevail in most extensive groups of species, and 
w^hich are perhaps even more common in those large families 
which consist of many closely allied genera. A suflScient proof 
of the overlapping of generic areas is the occurrence of a num- 
ber of genera of the same family together. Thus in France or 
Italy about twenty genera of warblers (Sylviadae) are found, 
and as each of the thirty-three genera of this family inhabiting 
temperate Europe and Asia has a different area, a great number 
must here overlap. So, in most parts of Africa at least, ten or 
twelve genera of antelopes may be found, and in South Amer- 
ica a large proportion of the genera of monkeys of the family 
Cebidffi occur in many districts ; and still more is this the case 
with the larger bird families, such as the tanagers, the tyrant 
shrikes, or the tree-creepers, so that there is in all these exten- 
sive families no genus whose area does not overlap that of many 
others. Then among the modemtely extensive families we find 
a few instances of one or two genera isolated from the rest, as 
the spectacled bear, Tremarctos, found only in Chili, while the 
remainder of the family extends from Europe and Asia over 
North America to the mountains of Mexico, but no farther 
south ; the Bovidse, or hollow-horned ruminants, which have a 
few isolated genera in the Kocky Mountains and the islands of 
Sumatra and Celebes ; and from these we pass on to the cases 
of wide separation already given. 

liestncted Areas of Families. — As families sometimes con- 
sist of single genem and even single species, they often present 
examples of very restricted range; but what is perhaps more 
interesting are those cases in which a family contains numerous 
species and sometimes even several genera, and yet is confined 
to a narrow area. Such are the golden moles (Chrysochloridoe), 
consisting of two genera and three species, confined to extra- 
tropical South Africa; the hill-tits (Liotrichidie), a family of 
eleven genera and thirty-five species almost wholly limited to 
the Uimalayas, but with a few straggling species in the Malay 
countries ; the Pteroptochidce, large wren-like birds, consisting 
of eight genera and nineteen specioB, almost entirely confined 



Chap. II.] THE ELEMENTARY FACTS OF DISTRIBUTION. 29 

to temperate South America and the Andes ; and the birds-of- 
paradise, consisting of nineteen or twenty genera and about 
thirty-five species, almost all inhabitants of New Guinea and 
the immediately surrounding islands, while a few, doubtfully 
belonging to the family, extend to East Australia. Among 
reptiles the most striking case of restriction is that of the rough- 
tailed burrowing snakes (Uropeltidfle), the five genera and eigh- 
teen species being strictly confined to Ceylon and the southern 
parts of the Indian Peninsula. 

The DiBtrihution of Orders, — When we pass to the larger 
groups, termed orders, comprising several families, we find com- 
paratively few cases of restriction and many of world-wide dis- 
tribution; and the families of which they are composed are 
strictly comparable to the genera of which families are com- 
posed, inasmuch as they present examples of overlapping, or 
conterminous, or isolated areas, though the latter are compara- 
tively rare. Among mammalia the Insectivora offer the best 
example of an order several of whose families inhabit areas 
more or less isolated from the rest ; while the Marsupialia have 
six families in Australia, and one, the opossums, far off in 
America. 

Perhaps, more important is the limitation of some entire 
orders to certain well-defined portions of the globe. Thus the 
Proboscidea, comprising the single family and genus of the ele- 
phants, and the Hyracoidea, that of the Hyrax or Syrian cony, 
are confined to parts of Africa and Asia; the Marsupials to 
Australia and America ; and the Monotrcmata, the lowest of all 
mammals — comprising the duck-billed Platypus and the spiny 
Echidna — to Australia. Among birds the Struthiones, or ostrich 
tribe, are almost confined to the three southern continents. South 
America, Africa, and Australia ; and among Amphibia the tailed 
Batrachia — the newts and salamander — are similarly restricted 
to the Northern Hemisphere. 

These various facts will receive their explanation in a future 
chapter. 



30 ISLAND LIFE. [Pabt 1. 



CHAPTER III. 

CLASSIFICATION OF THE FACTS OF DISTRIBUTION.— ZOOLOGICAL 

REGIONS. 

The Geographical Divisions of the Globe do not Correspond to Zoological Divisions. 
— The Range of British Mammals as Indicating a Zoological Region.— Range of 
East Asian and North African Mammals. — Tlie Range of British Birds. — Range 
of East Asian Birds. — The Limits of the Pala>arctic Region. — Characteristic Feat> 
ures of the Fal^arctic Region. — Definition and Characteristic Groups of the Ethi- 
opian Region. — Of the Oriental Region. — Of the Australian liegion. — Of the Ne- 
arctic Region. — Of the Neotropical Region. — Comparison of Zoological Regions 
with the Geographical Divisions of the Globe. 

Having now obtained some notion of how animals are dis- 
persed over the earth's surface, whether as single species or as 
collected in those groups termed genera, families, and orders, it 
will be well, before proceeding further, to understand something 
of the classification of the facts we have been considering, and 
some of the simpler conclusions these facts lead to. 

Wo have hitherto described the distribution of species and 
groups of animals by means of the great geographical divisions 
of the globe in common use ; but it will have been observed 
that in hardly any case do these define the limits of anything 
beyond species, and very seldom, or perhaps never, even those 
accurately. Thus the term "Europe" will not give, with any 
approach to accuracy, the range of any one genus of mammals 
or birds, and perhaps not that of half-a-dozen species. Either 
they range into Siberia, or Asia ^Minor, or Palestine, or North 
Africa ; and this seems to be always the case when their area 
of distribution occupies a largo portion of Europe. There are, 
indeed, a few species limited to Central or Western or Southern 
Europe, and these are almost the only cases in which we can 
use the word for zoological pui'poses without having to add to 
it some portion of another continent. Still less useful is the 



Chap. III.] ZOOLOGICAL REGIONS. 31 

term Asia for this purpose, since tliere is probably no single 
animal or group confined to Asia which is not also more or less 
nearly confined to the tropical or the temperate portion of it. 
The only exception is perhaps the tiger, which may really be 
called an Asiatic animal, as it occupies nearly two thirds of the 
continent; but this is a unique example, while the cases in 
which Asiatic animals and groups are strictly limited to a por- 
tion of Asia, or extend also into Europe or into Africa or to the 
Malay Islands, are exceedingly numerous. So, in Africa, very 
few groups of animals range over the whole of it without going 
beyond, either into Europe or Asia Minor or Arabia, while those 
which are purely African are generally confined to the portion 
south of the tropic of Cancer. Australia and America are terms 
which better serve the purpose of the zoologist. The former 
defines the limit of many important groups of animals; and the 
same may be said of the latter, but the division into North and 
South America introduces difficulties, for almost all the groups 
especially characteristic of South America are found also beyond 
the isthmus of Panama, in what is geographically part of the 
northern continent. 

It being thus clear that the old and popular divisions of the 
globe are very inconvenient when used to describe the range of 
animals, we are naturally led to ask whether any other division 
can be made which will be more useful, and will serve to group 
together a considerable number of the facts we have to deal 
with. Such a division was made by Mr. P. L. Sclater more than 
twenty years ago, and it has, with some slight modification, come 
into pretty general use in this country, and to some extent also 
on the Continent ; we shall therefore proceed to explain its nat- 
ure and the principles on which it is established, as it will have 
to be often referred to in future chapters of this work, and will 
take the place of the old geographical divisions, whose extreme 
inconvenience has already been pointed out. The primary 
zoological divisions of the globe are called " regions," and we 
will begin by ascertaining the limits of the region of which our 
own country forms a part. 

Tlie Range of British MammaU as Indicating a Zoological 
Region. — We will first take our commonest wild mammalia and 



32 



ISLAND LIFE. 



[Pabt I. 



see how far they extend, and especially whether they are eon- 
fined to Europe or range over parts of other continents : 



1. Wild-cat.. 

2. Fox 

3. Weasel... 

4. Otter 

r>. Badger... 
C. Stag 

7. Hedgehog 

8. Mole 

9. Squirrel . . 

10. Dormouse 

11. Water-rat. 

12. Hare 

13. liabbit. . . . 



Europe 



i( 
t( 
(( 
i( 

it 

4( 
i( 
t( 
(( 
(t 



North Africa 



it 
<t 
t( 
tt 
t( 



it 
(t 
t< 
(t 



North Africa 



Siberia, Afghanistan. 

Central Asia to Amoor. 
it t( tt 

Siberia. 

Central Asia to A moor, 
tt tt (t 

tt tt (t 

Central Asia. 

Central Asia to Amoor. 

Central Asia to Amoor. 
West Siberia, Persia. 



We thus see that out of thirteen of our commonest quadru- 
peds only one is confined to Europe, while seven are found also 
in Northern Africa and eleven range into Siberia, most of them 
stretching quite across Asia to the valley of the Amoor on the 
extreme eastern side of that continent. Two of the above-named 
British species, the fox and weasel, are also inhabitants of the 
New World, being as common in the northern parts of North 
America as they are with us ; but with these exceptions the en- 
tire range of our commoner species is given, and they clearly 
show that all Northern Asia and Northern Africa must be added 
to Europe in order to form the region which they collectively 
inhabit. If now we go into Central Europe and take, for exam- 
ple, the quadrupeds of Germany, we shall find that these too, al- 
though much more numerous, are confined to the same limits, 
except that some of the more arctic kinds, as already stated, ex- 
tend into the colder regions of North America. 

Range of East Asian and North African MammaU, — Let us 
now pass to the other side of the great northern continent, and 
examine the list of the quadrupeds of Amoorland, in the same 
latitude as Germany. We find that there are forty-four terres- 
trial species (omitting the bats, the seals, and other marine ani- 
mals), and of these no less than twenty-six are identical with 
European species, and twelve or thirteen more are closely allied 
representatives, leaving only five or six which are peculiarly 
Asiatic. We can hardly have a more convincing proof of the es- 
sential oneness of the mammalia of Europe and Northern Asia. 



Chap. III.] ZOOLOGICAL REGIONS. 33 

In Northern Africa we do not find so many European species 
(thongh even here they are very numerous), because a consider- 
able number of West Asiatic and Desert forms occur. Having, 
however, shown that Europe and Western Asia have ahnost 
identical animals, we may treat all these as really European, and 
we shall then be able to compare the quadrupeds of North Af- 
rica with those of Europe and West Asia. Taking those of Al- 
geria as the best known, we find that there are thirty-three spe- 
cies identical with those of Europe and West Asia, while twenty- 
four more, thongh distinct, are closely allied, belonging to the 
same genera; thus making a total of fifty-seven of European 
type. On the other hand, we have seven species which are either 
identical with species of tropical Africa or allied to them, and 
six more which are especially characteristic of the African and 
Asiatic deserts, which form a kind of neutral zone between the 
temperate and tropical regions. If now we consider that Algeria 
and the adjacent countries bordering the Mediterranean form 
part of Africa, while they are separated from Europe by a wide 
sea, and are only connected with Asia by a narrow isthmus, we 
cannot but feel surprised at the wonderful preponderance of the 
European and West Asiatic elements in the mammalia which 
inhabit the district. 

The Range of British Birds. — As it is very important that 
no doubt should exist as to the limits of the zoological region of 
which Europe forms a part, we will now examine the birds, in 
order to see how far they agree in their distribution with the 
mammalia. Of late yeara great attention has been paid to the 
distribution of European and Asiatic birds, many ornithologists 
having travelled in North Africa, in Palestine, in Asia Minor, in 
Persia, in Siberia, in Mongolia, and in China ; so that we are now 
able to determine the exact ranges of many species in a manner 
that would have been impossible a few years ago. These ranges 
are given for all British species in the new edition of Yarrell's 
"History of British Birds," now in coui*se of publication under 
the editorship of Professor Newton, while those of all European 
birds are given in still more detail in Mr. Dresser's beautiful 
work on the birds of Europe just completed. In order to con- 
fine our examination within reasonable limits, and at the same 

3 



34: ISLAND LIFE. [Part I. 

time give it the interest attaching to familiar objects, we will 
take the whole series of British Passeres, or perching birds, given 
in Professor Newton's work (118 in number), and arrange them 
in series according to the extent of their range. These include 
not only the permanent residents and regular migrants to our 
country, but also those which occasionally straggle here, so that 
it really comprises a large proportion of all European birds. 

I. British Birds which Extend to North Africa and Central or North- 

east Asia. 

1. Lanius collutio *. . . . . Red-backed Shrike (also all Africa) 

2. Oriolus yalbula Golden Oriole (also all Africa). 

3. Turdus musicus Song-thrush. 

4. ** iliacus Uedwing. 

r». ** pilaris Fieldfare. 

G. Monticola saxatilis Blue-rock Tlirush. 

7. Ruticilla Suecica Blue-throat (also India in winter). 

8. Saricola rubicola Stone-chat (also India in winter). 

9. ** ananlhe Wheat-ear (also North America). 

10. Acrocephalus arundinaceus Great Keed-warblcr. 

I I . Sylvia curruca Lesser White-throat. 

1 2. Parus major Great Titmouse. 

] 3. Motacilla sulphurea Gray Wagtail (also China and Malaya). 

U. " Rait Yellow Wagtail. 

1 5. Anthus trivialis Tree-pipit. 

16. * * spiloletta Water-pipit. 

17. * ' campestris Tawny Pipit. 

18. Ahuda arvensls Skylark. 

19. ** cristata Crested Lark. 

20. Emheriza schctniclus Heed-bunting. 

21. ' * citrinella Yellow-hammer. 

22. Fringilla montifringilla Brambling. 

23. Passer montanus Tree-sparrow (also South Asia). 

24. * * domesticus House-sparrow. 

2'). Cor.cothraustes vulgaris Hawfinch. 

20. Cardueiis spinus. Siskin (also China). 

27. Loxia curvirostra Crossbill. 

28. Sturnus vulgaris Starling. 

29. Pi/rrhocorax graculus Chough. 

30. Corvus corone Crow. 

31 . Hirundo rustica Swallow (all Africa and Asia). 

82. Cotyle riparia Sand-martin (also India and North America). 

2. British Birds which Range to Central or Northeast Asia. 

1 . Lanius excuhitor Great Grnv Shrike. 

2. Turdus varius White's Thrush (also to Japan). 



Chap. III.] ZOOLOGICAL llEGIONS. 35 

3. Turdus atrigularis* Black-throated Thrush. 

4. Acrocephalus noevius Grasshopper-warbler. 

i>. Phylloscopus superdliasus Yellow-browed Warbler. 

C. Certhia familiaris Ti*e©-creeper. 

7. Parus cceruleus Blue Titmouse. 

8. " ater. Coal Titmouse. 

9. ** palustris. Marsh Titmouse. 

10. Acreduia caudata Long-tailed Titmouse. 

1 1. Ampelis garrulus Waxwing. 

1 2. Anthus Richardi Richard's Pipit 

13. Alauda alpestris, Shore- lark (also North America). 

14. Plectrophanes nivalis Snow-buntitig (also North America). 

15. * ' Lapponicus, Jjapland Bunting. 

IG. Emheriza rustica Kustic Bunting (also China). 

17. *' pusilia Little Bunting. 

18. Linota linctria Mealy BedpoU (also North America). 

19. Pyrrhula Erythrina Scarlet Grossbeak (also North India, China). 

20. '* enucleatar Pine Grossbeak (also North America). 

21 . Loxia bifasciata Two-barred Crossbill. 

22. Pastor roseus. Kose-colored Starling (also India). 

23. Corvus corax Raven (also North America). 

24. Pica rustica Magpie. 

25. Nucifraga caryocatactes Nut-cracker. 

3. British Birds Ranging into North Africa and West Asia. 

1. Latdus minor Lesser Gray Shrike. 

2. ** auriculatus Wood-chat (also tropical Africa). 

3. Muacicapa grisola Spotted Flycatcher (also E. and S. Africa). 

4. " atricapilla Pied Flycatcher (also Central Africa). 

r», Tttrdus viscivorus. Mistletoe Thrush (North India in winter). 

6. ** merula Blackbird. 

7. *' torquatus Ring-ouzel. 

8. Accentor modularis Hedge-sparrow. 

9. Krithticus rubectda Redbreast. 

] 0. Daulias luscima Nightingale. 

] I . Ruticilla phanicwrus Redstart. 

12. ** Tithys Black Redstai-t 

] 3. Saxicola rubetra Whinchat. 

1 4. ASdon galactodes Rufous Warbler. 

] .*». Acrocephalus streperus Reed- warbler. 

16. ** schcenobenus Sedge- warbler. 

17. MeHzopkilus undatus Dartford Warbler. 

18. Sylvia ru/a Greater White-throat. 

19. * ' saliearia Garden-warbler. 

20. *' atricapilla Blackcap. 

21. ** orphea Orphean Warbler. 

22. Phylloscopus sibilatrix Wood-wren, 



36 ISLAND LIFE. [Part L 

23. Phylloscopus trochiius Willow-wren. 

24. * ' collyhita Chiffchaff 

25. ReguluB cristatus Golden-crested Wren. 

26. * ' ignicapillta Fire-ci-ested Wren. 

27. Troglodytes parvulus , Wren. 

28. Sitta cctsia Nutlmteh. 

29. Motacilla alba White Wagtail (also West Africa). 

80. ** flava Blue-headed Wagtail. 

8 1 . Anthus praterms, Meadow-pipit. 

82. Alauda arhorea Woodlark. 

83. Calandrella hrachydactyla Short-toed Lark. 

84. Emheriza milaria .*.... Common Buftting. 

85. " cirlus Cirl Banting. 

86. ** horiulana Ortolan. 

37. Fringilla Calebs Chaffinch. 

88. Coccothraustes chloris, Greenfinch. 

89. Serinus hortulanus, Serin. 

40. Carduelis elegans Goldfinch. 

41. Linota cannabina Linnet. 

42. Corvus monedula Jackdaw. 

43. Chelidon urbica House-maitin. 

4. British Birds Ranging to North Africa. 

1. Uypolais icterina Icterine Warbler. 

2. Acrocephalus aquaticus Aquatic Warbler. 

8. ** luscinioides Savi's Warbler. 

4. Motacilla lugubris *. Pied Wagtail. 

5. Pyrrhula Europata Bullfinch. 

C. Gatrulus glandaHus Jay. 

5. British Birds Hanging to West Asia only. 

1 . Muscicapa parva Ked-breasted Flycatcher (to Northwest India). 

2. Panttrus biarmicus Bearded Titmouse. 

8. Melanocorypha Sibirica White-winged Lark. 

4. Euspiza metanocephala Blnck-headed Bunting. 

5. Linota JlavirostHs Twite. 

C. Corvus frugilegus Rook. 

C. British Birds Confined to Europe. 

1. Cinclus aquaticus Dipper. 

2. Accentor collaris Alpine Accentor. 

8. Parus cristatus Crested Titmouse. 

4. Anthus obscurus Rock-pipit. 

5. Linota rufescens. Lesser Redpoll. 

G. Loxia pityopsittacus Parrot Crossbill. 



Chap. III.] ZOOLOGICAL REGIONS. 37 

We find that out of a total of 118 British Passeres there arc : 

32 species which range to North Africa and Central or East Asia. 

25 " *' »» " Central or East Asio, but not to North Afdca. 

43 ** ** ** " North Afnca and Western Asia. 

G *' " ** " North Africa, but not at all into Asia. 

6 ** ** ** *' West Asia, but not to North Africa. 

G ^* *^ do not range oat of Europe. 

These figures agree essentially with those furnished by the 
mammalia, and complete the demonstratioa that all the temper- 
ate portions of Asia and North Africa must be added to Europe 
to form a natural zoological division of the earth. We must also 
note how comparatively few of these overpass the limits thus 
indicated ; only seven species extending their range occasionally 
into tropical or South Africa, eight into some parts of tropical 
Asia, and six into arctic or temperate North America. 

Range of East Asian Birds, — To complete the evidence, we 
only require to know that the East Asiatic birds are as much 
like those of Europe as we have already shown to be the case 
when we take the point of departure from our end of the conti- 
nent. This does not follow necessarily, because it is possible that 
a totally distinct North Asiatic fauna might there prevail ; and, 
although our birds go eastward to the remotest parts of Asia, 
their birds might not come westward to Europe. The birds of 
Eastern Siberia have been carefully studied by Hussian natural- 
ists, and afford us the means of making the required comparison. 
There are 151 species belonging to the orders Passeres and Pica- 
rise (the perching and climbing birds), and of these no less than 
77, or more than half, are absolutely identical with European 
species ; 63 are peculiar to North Asia, but all except five or six 
of these are allied to European forms; the remaining 11 spe- 
cies are migrants from Southeastern Asia. The resemblance is 
therefore equally close whichever extremity of the Euro- Asiatic 
continent we take as our starting-point, and is equally remarkable 
in birds as in mammalia. We have now only to determine the 
limits of this our first zoological region, which has been termed 
the " Palsearctic " by Mr. Sclater, meaning the " northern old- 
world " region — a name now well known to naturalists. 

The Limits of the Palwarctic Begion. — The boundaries of 



38 ISLAND LIFE. [Pabt I. 

this region, as nearly as they can be ascertained, are shown on 
our general map at the beginning of this chapter, but it will be 
evident on consideration that, except in a few places, its limits 
can only be approximately defined. On the north, east, and 
west it extends to the ocean, and inclades a number of islands 
whose peculiarities will be pointed out in a subsequent chapter ; 
so that the southern boundary alone remains ; but as this runs 
across the entire continent from the Atlantic to the Pacific 
Ocean, often traversing little-known regions, we may perhaps 
never be able to determine it accurately, even if it admits of 
such determination. In drawing the boundary-line across Af- 
rica we meet with our first diflSculty. The Euro-Asiatic ani- 
mals undoubtedly extend to the northern borders of the Sahara, 
while those of tropical Africa come up to its southern margin, 
the desert itself forming a kind of dry sea between them. Some 
of the species on either side penetrate and even cross the desert, 
but it is impossible to balance these with any accuracy, and it 
has therefore been thought best, as a mere matter of conven- 
ience, to consider the geographical line of the tropic of Cancer 
to form the boundarv. We are thus enabled to define the Pa- 
Isearctic region as including all north temperate Africa ; and a 
similar intermingling of animal types occurring in Arabia, the 
same boundary-line is continued to the southern shore of the 
Pereian Gulf. Persia and Afghanistan undoubtedly belong to 
the Palsearctic region, and Beloochistan should probably go with 
these. The boundary in the northwestern part of India is again 
difficult to determine, but it cannot be far one way or the other 
from the river Indus as far up as Attock, opposite the mouth of 
the Cabool Eiver. Here it will bend to the southeast, passing 
a little south of Cashmere, and along the southern slopes of the 
Himalayas into East Thibet and China, at heights varying from 
9000 to 11,000 feet, according to soil, aspect, and shelter. It 
may, perhaps, be defined as extending to the upper belt of for- 
ests as far as coniferous trees prevail ; but the temperate and 
tropical faunas are here so intermingled that to draw any exact 
parting-line is impossible. The two faunas are, however, very 
distinct. In and above the pine woods there are abundance of 
warblera of northern genera, with wrens, numerous titmice, and 



CiiAP.ITL] ZOOLOGICAL REGIONS. 39 

a great variety of buntings, grossbeaks, bullfinches, and rosefincli- 
es, all more or less nearly allied to the birds of Europe and 
Northern Asia ; while a little lower down we meet with a host 
of peculiar birds allied to those of tropical Asia and the Malay 
Islands, but often of distinct genera. There can be no doubt, 
therefore, of the existence here of a pretty sharp line of demar- 
cation between the temperate and tropical faunas, though this 
line will be so irregular, owing to the complex system of valleys 
and ridges, that in our present ignorance of much of the coun- 
try it cannot be marked in detail on any map. 

Fartlier east in China it is still more difficult to determine 
the limits of the region, owing to the great intermixture of mi- 
grating birds ; tropical forms passing northward in summer as 
far as the Amoor Kiver, while the northern forms visit every 
part of China in winter. From what we know, however, of the 
distribution of some of the more typical northern and southern 
species, we are able to fix the limits of the Palsearctic region a 
little south of Shanghai on the coast. Several tropical genera 
come as far as Ningpo or even Shanghai, but rarely beyond ; 
while in Formosa and Amoy tropical forms predominate. Such 
decidedly northern forms as bullfinches and hawfinches are 
found at Shanghai ; hence we may commence the boundarj-- 
line on the coast between Shanghai and Ningpo, but inland it 
probably bends a little southward, and then northward to the 
mountains and valleys of West China and East Thibet in about 
32° north latitude; where, at Moupin,a French missionary, Pere 
David, made extensive collections showing this district to be at 
the junction of the tropical and temperate faunas. Japan, as a 
whole, is decidedly Palaearctic, although its extreme southern 
portion, owing to its mild insular climate and evergreen vegeta- 
tion, gives shelter to a number of tropical forms. 

Characteristic Features of the Palmarctic Region. — Having 
thus demonstrated the unity of the Palsearctic region by tracing 
out the distribution of a large proportion of its mammalia and 
birds, it only remains to show how far it is ch»iracterized by pe- 
culiar groups such as genera and families, and to say a few words 
on the lower forms of life which prevail in it. 

Taking first the mammalia, we find this region is distinguished 



40 ISLAND LIFE. [Part L 

by its possession of tlie entire family of Talpidse, or moles, con- 
sisting of eight genera and sixteen species, all of which are con- 
lined to it except one which is found in Northwest America, 
and two which extend to Assam and Formosa. Among carniv- 
orous animals the lynxes (nine species) and the badgers (two spe- 
cies) are peculiar to it in the Old World, while in the New the 
lynxes are found only in the colder regions of North America. 
It has six peculiar genera (with seven species) of deer; seven 
peculiar genera of Bovidae, chiefly antelopes ; while the entire 
group of goats and sheep, comprising twenty-two species, is al- 
most confined to it, one species only occurring in the Rocky 
Mountains of North America and another in the Neilgherries 
of Southern India. Among the rodents there are nine genera 
with twenty-seven species wholly confined to it, while several 
others, as the voles, tlie dormice, and the pikas, have only a few 
species elsewhere. 

In birds there are a large number of peculiar genera, of which 
we need only mention a few of the more important, as the grass- 
hopper-warblers (Locustella) with seven species, the Accentors 
with twelve species, and about a dozen other genera of warblere, 
including the robins ; the bearded titmouse and several allied 
genera; the long-tailed titmice forming the genus Acredula; 
the magpies, choughs, and nut-crackers ; a host of finches, among 
which the bullfinches (Pyrrhula) and the buntings (Emberiza) 
are the most important. The true pheasants (Phasianus) are 
wholly Palflearctic, except one species in Formosa, as are several 
genera of wading birds. Though the reptiles of cold countries 
are few as compared with those of the tropics, the Palaearctic 
region in its warmer portions has a considerable number, and 
among these are many which are peculiar to it. Such are two 
genera of snakes, seven of lizards, eight of frogs and toads, and 
eight of newts and salamanders; while of fresh -water fishes 
there are about twenty peculiar genera. Among insects we 
may mention the elegant Apollo butterflies of the Alps as form- 
ing a peculiar genus (Parnassius), only found elsewhere in the 
Kocky Mountains of North America; while the beautiful genus 
Thais of the South of Europe and Sericinus of North China are 
equally remarkable. Among other insects we can now only refer 



Chap.IIL] zoological REGIONS. 41 

to the great family of Carabidse, or predaceous ground beetles, 
which are immensely numerous in this region, there being 
about fifty peculiar genera; while the large and handsome ge- 
nus Carabus, with its allies Procerus and Procrustes, containing 
nearly three hundred species, is almost wholly confined to this 
region, and would alone serve to distinguish it zoologically from 
all other parts of the globe. 

Having given so full an exposition of the facts which deter- 
mine the extent and boundaries of the Palsearctic region, thei*e 
is less need of entering into much detail as regards the other 
regions of the Eastern Hemisphere; their boundaries being 
easily defined, while their forms of animal life are well marked 
and strongly contrasted. 

Definition and Characteristic Groups of the Ethiopian He- 
ffion, — The Ethiopian region consists of all tropical and South 
Africa, to wliich is appended the large island of Madagascar, and 
the Mascai'ene Islands to the east and north of it, though these 
differ materially from the continent, and will have to be dis- 
cussed in a sepai-ate chapter. For the present, then, we will 
take Africa south of the tropic of Cancer, and consider how 
far its animals are distinct from those of the Palsearctic re- 
gion. 

Taking first the mammalia, we find the following remarkable 
animals at once separating it from the Palaearctic and every oth- 
er region. The gorilla and chimpanzee, the baboons, numerous 
lemurs, the lion, the spotted hyena, the aard-wolf and hyena- 
dog, zebras, the hippopotamus, giraffe, and more than seventy 
peculiar antelopes. Here we have a wonderful collection of 
large and peculiar quadrupeds; but the Ethiopian region is also 
characterized by the absence of others which are not only abun- 
dant in the Patearctic region, but in many tropical regions as 
well. The most remarkable of these deficiencies are the bears, 
the deer, and wild oxen, all of which abound in the tropical 
parts of Asia, while bears and deer extend into both North and 
South America. Besides the large and conspicuous animals 
mentioned above, Africa possesses a number of completely iso- 
lated groups; such are the potamogale, a curious otter-like wa- 



42 ISLAND LIFE. [Pakt L 

ter-sbrew, discovered by Du Chaillu in West Africa, so distinct 
as to constitute a new family, Potamogalidae ; the golden moles, 
also forming a peculiar family, Chrysochloridae ; as do the ele- 
phant-shrews, MacroscelididsB ; the singular aard-varks, or earth- 
pigs, forming a peculiar family of Edentata, called Orycteropo- 
didse; while there are numerous peculiar genera of monkeys, 
swine, civets, and rodents. 

Among birds the most conspicuous and remarkable are the 
great-billed vulture-crows (Corvultnr), the long-tailed whydah 
finches (Vidua), the curious ox-peckers (Buphaga), the splendid 
metallic starlings (Lamprocolius), the handsome plantain-eaters 
(Musophaga), the ground -hornbills (Bucorvus), the numerous 
guinea-fowls belonging to four distinct genera, the serpent-eat- 
ing secretary-bird (Serpentarius), the huge boat- billed heron 
(Balaeniceps), and the true ostriches. Besides these there are 
three quite peculiar African families, the Musophagidse, or plan- 
tain-eatere, including the elegant crested touracos; the curious 
little finch-like colies (Coliidse), and the Irrisoridae, insect-eating 
birds allied to the hoopoes, but with glossy metallic plumage 
and arboreal habits. 

In reptiles, fishes, insects, and land shells, Africa is very rich, 
and possesses an immense number of peculiar forms. These are 
not suflSciently known to require notice in a work of this char- 
acter, but we may mention a few as mere illustrations ; the puff- 
adders, the most hideous of poisonous snakes; the chameleons, 
the most remarkable of lizards ; the goliath-beetles, the largest 
and handsomest of the Cetoniidce ; and some of the Achatinse, 
which are tlie largest of all known land shells. 

Definition and Characteristic Groups of the Oriental Region, 
— The Oriental region comprises all Asia south of the Palae- 
arctic limits, and along with this the Malay Islands as far as the 
Philippines, Borneo, and Java. It was called the Indian region 
by Mr. Sclater ; but this term has been objected to because the 
Indo-Chinese and Malayan districts are the richest and most 
characteristic, while the peninsula of India is the poorest por- 
tion of it. The name " Oriental" has therefore been adopted in 
my work on "The Geographical Distribution of Animals" as 
preferable to either Malayan or Indo-Australiun, both of which 



Chap. III.] ZOOLOGICAL REGIONS. 43 

have been proposed, but are objectionable, as being already in 
use in a different sense. 

The great features of the Oriental region are the long-armed 
apes, the orang-outangs, the tiger, the sun-bears and honey-bears, 
the tapir, the chevrotains or mouse-deer, and the Indian ele- 
phant. Its most conspicuous birds are the immense number and 
variety of babbling-thrushes (Timaliidflp), its beautiful little hill- 
tits (Liotrichidse), its green bulbuls (Phyllornithidee), its many 
varieties of the crow family, its beautiful gapers and pittas 
adorned with the most delicate colors, its great variety of horn- 
bills, and its magnificent Phasianidae, comprising the peacocks, 
argns-pheasants, fire-backed pheasants, and jungle-fowl. Many 
of these are, it is true, absent from the peninsula of Hindostan, 
but suflScient remain there to ally it with the other parts of the 
region. 

Among the remarkable but less conspicuous forms of mam- 
malia which are peculiar to this region are, monkeys of the 
genus Presbyter, extending to every part of it ; lemurs of three 
peculiar genera — ^Nycticebus and Loris (slow lemurs) and Tar- 
sius (spectre lemurs); the flying lemur (Galeopithecus), now 
classed as a peculiar family of Insectivora and found only in the 
Malay Islands ; the family of the Tupaias, or squirrel-shrews, 
curious little arboreal Insectivora somewhat resembling squir- 
rels ; no less than twelve peculiar genera of the civet family, 
three peculiar antelopes, five species of rhinoceros, and the 
round-tailed flying squirrels forming the genus Pteromys. 

Of the peculiar groups of birds we can only mention a few. 
The curious little tailor -birds, of the genus Orthotomus, are 
found over the whole region, and almost alone serve to charac- 
terize it, as do the fine laughing-thrushes, forming the genus 
Garrnlax ; while the beautiful grass-green fruit-thrushes (Phyl- 
lornis), and the brilliant little minivets (Pericrocotns), are almost 
equally universal. Woodpeckers are abundant, belonging to a 
dozen peculiar genera ; while gaudy barbets and strange forms 
of cuckoos and hornbills are also to be met with everywhere. 
Among game birds, the only genus, that is universally distrib- 
uted, and which may be said to characterize the region, is Qal- 
Ins, comprising the true jungle-fowl, one of which, GdUvs Ban- 



ISLAND LIFE. 



iVxKV I 



kiva, is found froiii tlio Iliinalayae and Central India to Ma- 
lacca, Java, and even eastward to Timor, and is the undoubted 
origiu of almost all our domestic poultry. Southern India and 
Ceylon each possess distinct species of jungle-fowl, and a third 
very Iiaiidsoiiio green bird {Gallus wtieus) inhabits Java. 

Iteptiles arc as abundant as in Africa, but they present no 
wcll-kiiown groups whieh cau be considered as specially charac- 
teristic. Among insects we may notice the magnificent golden 
iiiid green Papilionidie of various genera as being unequalled in 
the world; while the great Atlas moth is probably the most 
gigantic of Lepidopteru, being sometimes ten inches across the 
wings, which are also very broad. Among the beetles the 
Btrange fiat-bodied Malayan mormolyce is tlio largest of all the 
Carabidte, while the catoxautha is equally a giant among the 
Bnprestidie. On the whole, the insects of this region probably 
surpass those of any other part of the world, except South 
America, in size, variety, and beanty. 

Z>>^nition and CAara-cteristii! Groups of the Australian He- 
ffitMi. — The Australian region is so well marked off from the 
Oriental, as well as from all other parts of the world, by zoologi- 
cal peculiarities that we need not take up much time in describ- 
ing it. especially as some of its component islands will como 
under review at a subsequent stage of our work. Its most im- 
portant portions are Australia and New Guinea, but it also in- 
cludes all the Malayan and Pacific Islands to the cast of Borneo, 
Java, and Bali, the Oriental region terminating with the sub- 
marine bank on which those islands are situated. Tijc island of 
Celubea is inclnded in this region from a balance of considera- 
tions, but it almost equally well belong to the Oriental, and 
must be left out of the account in our general sketch of the zoo- 
logical features of the Australian region. 

The great feature of the Australian region is the almost total 
absence of all the forms of mammalia wliicli abound ia the rest 
of the world, their place being supplied by a great variety of 
marsupials. In Australia and New Guinea there are no Insec- 
tivora, Oarnivora, nor Ungulata, while even the rodents are only 
represented by a few small rats and mice. In the Pacific Islands 
nnimmals are altogether absent (except perhaps in \ew Ze.iland), 



Chap. III.] ZOOLOGICAL REGIONS. 45 

but in the Moluccas and other islands bordering on the Oriental 
region the higher mammals are represented by a few deer, civets, 
and pigs, though it is doubtful whether the two former may not 
have been introduced by man, as was almost certainly the case 
with the semi-domesticated dingo of Australia. These peculi- 
arities in the mammalia are so great that every naturalist agrees 
that Australia must be made a separate region, the only differ- 
ence of opinion being as to its extent, some thinking that New 
Zealand should form another separate region ; but this question 
need not now delay us. 

In birds Australia is by no means so isolated from the rest of 
the world, as it contains great numbers of warblers, thrushes, fly- 
catchers, shrikes, crows, and other familiar types of the Eastern 
Hemisphere ; yet a considerable number of the most character- 
istic Oriental families are absent. Thus there are no vultures, 
woodpeckers, pheasants, bulbuls, or barbets in the Australian 
region ; and the absence of these is almost as marked a feature 
as that of cats, deer, or monkeys among mammalia. The most 
conspicuous and characteristic birds of the Australian region 
are, the piping-crows ; the honey-suckers (Meliphagidae), a family 
quite peculiar to the region ; the lyre-birds ; the great terrestrial 
kingfishers (Dacelo); the great goat-suckers, called more-porks in 
Australia, and forming the genus Podargus ; the wonderful 
abundance of parrots, including such remarkable forms as the 
white and the black cockatoos, and the gorgeously colored brush- 
tongued lories ; the almost equal abundance of fine pigeons more 
gayly colored than any others on the globe ; the strange brush- 
turkeys and mound-builders, the only birds that never sit upon 
their eggs, but allow them to be hatched, reptile-like, by the 
heat of the sand or of fermenting vegetable matter; and, lastlj-, 
the emus and cassowaries, in which the wings are far more rudi- 
mentary than in the ostriches of Africa and South America. 
New Guinea and the surrounding islands are remarkable for 
their tree-kangaroos, their birds-of-paradise, their raquet-tailed 
kingfishers, their great crown-pigeons, their crimson lories, and 
many other remarkable birds. This brief outline being suffi- 
cient to show the distinctness and isolation of the Australian 
region, we will now pass to the consideration of the Western 
Hemisphere. 



[Pawl 

Dejinition and Vharacterintio Groups of (he A'earctic Sfgion. 
— The Neavctic region coinpi-ises all temiierate and arctic North 
America, including Greenland, t!ie only doubt Iviing 8S to its 
BontLern boundiiry, many nortliem types iieiietratiug into the 
tropical zone by means of the bigliland& lutd volcanic peaks of 
Mexico and Guatemala, while a few which are characteristic of 
the tropica extend northward into Texas nnd California. There 
IB, liowever, considerable evidence showing that on the east 
coast the Rio Grande del Norte, and ou the west a point nearly 
opposite Capo St. Lucas, form the most natural boundary; but 
instead of being drawn straight across the line bends to the 
southeast as Boon as it rises on the flanks of tlie table-land, f orm< 
ing a deep loop which extends some distance beyond the city 
of Mexico, and perhaps ought to be continued along the higher 
ridges of Guatemala. 

The Nearctic region is so similar to the Paliearetio in posi- 
tion nnd climate, and the two so closely approach each other at 
Behring Strait, that we cannot wonder at there being a certain 
amount of similarity between them — a similarity whith some 
natui'olists have so far overestimated as to think that the two 
regions ought to be united. Let us therefore carefully examine 
the special zoological features of this region, and see how far it 
resembles, and how far differs from, the Palsearctic. 

At first sight the niauiinnlia of North America do not seem 
to differ much from those of Europe or Northern Asia. There 
are cats, lynxes, wolves and foxes, weasels, beara, elk and deer, 
voles, beavci'6, squirrels, marmots, and bares, all very similar to 
those of the Eastern Hemisphere, and several Iiardly distinguish- 
able. Even tlio bison or "bnffalo" of the prairies, once so 
abundant and characteristic, is a close ally of the now almost 
extinct "aurochs" of Litlinania. Here, then, we undoubtedly 
find a very close resemblance between the two regions; and if 
this wore all, we should have great difficulty in separating them. 
But along wilh these we tind another set of mamnmls, not quite 
60 eonspicuous, but nevertheless very important, Wt- have, first, 
three peculiar genera of moles, one of which, the star-nosed 
mole, is a most extraordinary creature, quite unlike anything 
else. Then there are three genera of the weasel family, inchid- 



Chap. III.] ZOOLOGICAL REGIONS. 47 

ing the well-known skunk (Mephitis), all quite different from 
Eastern forms. Then we come to a peculiar family of carniv- 
ora, the raccoons, very distinct from anything in Europe or 
Asia ; and in the Eocky Mountains we lind the prong-horn an- 
telope (Antilocapra) and the mountain - goat of the trappere 
(Aplocerus), both peculiar genera. Coming to the rodents, we 
find that the mice of America differ in some dental peculiarities 
from those of the rest of the world, and thus form several dis- 
tinct genera ; the jumping-mouse (Xapus) is a peculiar form of 
the jerboa family, and then we come to the pouched rats, Ge- 
omyidse, a very curious family, consisting of four genera and 
nineteen species, peculiar to North America, though not con- 
fined to the Nearctic region. The prairie-dogs (Cynomys), the 
tree - porcupine (Erethizon), the curious sewellel (Haploodon), 
and the opossum (Didelphys) complete the list of peculiar mam- 
malia which distinguish the northern region of the New World 
from that of the Old. We must add to these peculiarities some 
remarkable deficiencies. The Nearctic region has no hedge- 
hogs, nor wild -pigs, nor dormice, and only one wild -sheep in 
the Kocky Mountains, as against twenty species of sheep and 
goats in the Palsearctic region. 

In birds also the similarities to our own familiar songsters 
first strike us, though the differences are perhaps really greater 
than in the quadrupeds. We see thmshes and wrens, tits and 
finches, and what seem to be warblers and flycatchci*s and star- 
lings in abundance; but a closer examination shows the orni- 
thologist that what he took for the latter are really quite dis- 
tinct, and that there is not a single true flycatcher of the family 
Muscicapidse, or a single starling of the family Sturnidae, in the 
whole continent ; while there are very few tnie warblere (Syl- 
viidae), their place being taken by the very distinct families 
Mniotiitidie, or wood-warblens, and Vireonida^, or greenlets. In 
like manner the flycatchers of America belong to the totally 
distinct family of tyrant-birds, Tymnnidse, and those that look 
like starlings to the hang-nests, Icteridse; and these four pecul- 
iar families comprise more than a hundred species, and give a 
special character to the ornithology of the country. Add to 
these such peculiar birds as the mocking-thrushes (Mimus), the 



iS 



ISLAND LIFE. 



[Pa 



blue jays (Cyanoeitta), tlie tanagers, the peculiar genera of cuck- 
oos (Coccygufl and Crotophaga), the humming-birds, the wild- 
tni-kej-s (Ueleagris), and the turkey-buzzards (Cathartes), and we 
see that if there is any doubt as to the mammals of North Amer- 
ica being sufficiently distinct to justify the creation of a sepa- 
rate region, the evidence of the birds would nlono settle the 
question. 

The reptiles, and some othere of the lower animals, add still 
more to this weight of evidence. The true rattlesnakes are 
highly characteristic, and among the lizards are several genera 
of the peculiar American family the IguanidiE. Nowhere in 
the world are the tailed batrachJans so largely developed as in 
this region, the Sirens and the Ainpliiumidfe forming two pe- 
culiar families; wliilo there are nine peculiar genera of salaman- 
ders, and two others allied respectively to tlic Proteus of Europe 
and the Sieboldia, or giant salamander, of Japan. There are 
about twenty-nine peculiar genera of fresh-water fishes; while 
the fresh-water mollnsks are more numerous than in any other 
region, more than thirteen hundred species and varieties having 
been described. 

Combining the evidence derived from all these classes of ani- 
mals, we find the Nearctic region to be exceedingly well char- 
acterized, and to be amply distinct from the Paltearctic. The 
few species that are common to the two are almost all arctic, or 
at least northern, types, and may be compared with those desert 
forms which occuiiy tlie debatable ground between the Paliearc- 
tic. Ethiopian, and Oriental regions. If, however, we compare 
the number of species which are common to tlie Neai-ctic and 
Paltearctic regions with the number common to the western and 
eastern extremities of the latter region, we shall find a wonder- 
ful difference between the two eases; and if we further call to 
mind the number of important groups characteristic of the one 
region but absent from the other, we shall be obliged to admit 
that the relation that undoubtedly exists between the faunas of 
North America and Europe is of a very distinct nature from 
that which connects together Western Europe and Nortbeastcm 
Asia in the bonds of zoological nnitj'. 

Definition ami Charact^rititic Groups of the Neotropical lie- 



Chap. III.] ZOOLOGICAL REGIONS. 49 

gion. — The Neotropical region requires very little definition, 
since it comprises the whole of America south of the Nearctic 
region, with the addition of the Antilles or West Indian Islands. 
Its zoological peculiarities are almost as marked as those of Aus- 
tralia, which, however, it far exceeds in the extreme richness and 
variety of all its forms of life. To show how distinct it is from 
all the other regions of the globe, we need only enumerate some 
of the best known and more conspicuous of the animal forms 
which are peculiar to it. Such are, among mammalia, the pre- 
hensile-tailed monkeys and the marmosets, the blood-sucking 
bats, the coati-mundis, the peccaries, the llamas and alpacas, the 
chinchillas, the agoutis, the sloths, the armadillos, and the ant- 
eaters — a series of types more varied, and more distinct from 
those of the rest of the world, than any other continent can boast 
of. Among birds we have the charming sugar-birds, forming 
the family Cosrebidse, the immense and wonderfully varied 
group of tanagers, the exquisite little manakins, and tho gor- 
geously colored chatterers ; the host of tree-creepers of tho fam- 
ily Dendrocolaptidae, the wonderful toucans, the puff-birds, jaca- 
mars, todies, and motmots; the marvellous assemblage of four 
hundred distinct kinds of humming-birds, the gorgeous macaws, 
the curassows, the trumpeters, and the sun-bitterns. Here again 
there is no other continent or region that can produce such an 
assemblage of remarkable and perfectly distinct groups of birds ; 
and no less wonderful is its richness in species, since these fully 
equal, if they do not surpass, those of tho two great tropical re- 
gions of the Eastern Hemisphere (the Ethiopian and the Ori- 
ental) combined. 

As an additional indication of the distinctness and isolation 
of the Neotropical region from all others, and especially from 
the whole Eastern Hemisphere, wo must say something of the 
otherwise widely distributed groups which are absent. Among 
mammalia we have first the order Insectivora, entirely absent 
from South America, though a few species are found in Central 
America and the West Indies ; the Viverridae, or civet family, are 
wholly wanting, as is every form of §heep, oxen, or antelopes; 
while the swine, the elephants, and the rhinoceroses of the Old 
World are represented by the diminutive peccaries and tapirs. 

4 



50 ISLAND LIFE. [Pabt L 

Among birds wc have to notice the absence of tits, true fly- 
catchei^s, shrikes, sun-birds, starlings, larks (except a solitary spe- 
cies in the Andes), rollers, bee-eaters, and pheasants; while war- 
blers are very scarce, and the almost cosmopolitan wagtails are 
represented by a single species of pipit. 

We must also notice the preponderance of low or archaic 
types among the animals of South America. Edentates, marsu- 
pials, and rodents form the majority of the terrestrial mammalia; 
while such higher groups as tlie carnivora and Iioofed animals 
are exceedingly deficient. Among birds a low type of Passeres, 
characterized by the absence of the singing-muscles, is excessive- 
ly prevalent, tlie enormous groups of the ant-thrushes, tyrants, 
tree-creepers, manakins, and chatterers belonging to it. The 
Picariae (a lower group) also prevail to a far greater extent than 
in any other regions, both in variety of forms and number of 
species; and the chief representatives of the gallinaceous birds 
— the curassows and tinamous — are believed to be allied, the for- 
mer to the brush-turkeys of Australia, the latter (very remotely) 
to the ostriches, two of the least-developed types of birds. 

Wliether, therefore, we consider its richness in peculiar forms 
of animal life, its enormous variety of species, its numerous de- 
ficiencies as compared with other parts of the world, or the prev- 
alence of a low type of organization among its higher animals, 
the Neotropical region stands out as undoubtedly the most re- 
markable of the great zoological divisions of the earth. 

In reptiles, amphibia, fresh-water fishes, and insects, this region 
is equally peculiar, but we need not refer to these here, our only 
object now being to establish by a suflicient number of well- 
known and easily remembered examples tlie distinctness of each 
region from all othere, and its unity as a wliole. The former has 
now been sufficiently demonstrated, but it may be well to say a 
few words as to the latter point. 

The only outlying portions of the region about which there 
can be any doubt are. Central America, or that part of the region 
north of the Isthmus of Panama, the Antilles, or West Indian 
Islands, and the temperate portion of South America, including 
Chili and Patagonia. 

In Central America, and especially in Mexico, we have an in- 



CHAP.m.] ZOOLOGICAL REGIONS. 51 

terinixture of South American and North American animals, 
but the former undoubtedly predominate, and a large proportion 
of the peculiar Neotropical groups extend as far as Costa Rica. 
Even in Guatemala and Mexico we have howling and spider 
monkeys, coati-mundis, tapirs, and armadillos ; while chatterers, 
manakins, ant-thrushes, and other peculiarly Neotropical groups 
of birds are abundant. There is therefore no doubt as to Mexico 
forming part of this region, although it is comparatively poor, 
and exhibits the intermingling of temperate and tropical forms. 

The West Indies are less clearly Neotropical, their poverty in 
mammals as well as in most other groups being extreme, while 
great numbers of North American birds migrate there in winter. 
The resident birds, however, comprise trogons, sugar-birds, chat- 
terers, with many humming-birds and parrots, representing eigh- 
teen peculiar Neotropical genera — a fact which decides the re- 
gion to which the islands belong. 

South temperate America is also very poor as compared with 
the tropical parts of the region, and its insects contain a consid- 
erable proportion of north temperate forms. But it contains ar- 
madillos, cavies, and opossums ; and its birds are all of American 
groups, though, owing to the inferior climate and deficiency of 
forests, a number of the families of birds peculiar to tropical 
America are wanting. Thus there are no manakins, chatterers, 
toucans, trogons, or motmots ; but there are abundance of hang- 
nests, tyrant-birds, ant-thrushes, tree-creepers, and a fair propor- 
tion of humming-birds, tanagers, and parrots. The zoology is 
therefore thoroughly Neotropical, although somewhat poor ; and 
it has a number of peculiar forms, as the chinchillas, alpacas, etc., 
whioh are not found in the tropical regions except in the high 
Andes. 

Comparison of Zoological Regions with the Oeographical Di- 
visions of the Globe. — Having now completed our survey of the 
great zoological regions of the globe, we find that they do not 
differ so much from the old geographical divisions as our first 
example might have led us to suppose. Europe, Asia, Africa, 
Australia, North America, and South America really correspond, 
each to a zoological region, but their boundaries require to be 
modified more or less considerably ; and if ^te remember this, 



62 ISLAND LIFE. [Part L 

and keep tlieir extensions or limitations always in our mind, we 
may use the terms " South American " or " North American " 
as being equivalent to Neotropical and Nearctic, without much 
inconvenience ; while " African " and " Australian " equally well 
serve to express the zoological types of the Ethiopian and Aus- 
tralian regions. Europe and J^sia. require more important mod- 
ifications. The European fauna does indeed well represent the 
Palflearctic in all its main features ; and if instead of Asia we say 
tropical Asia, we have the Oriental region very fairly defined; 
so that the relation of the geographical and the zoological pri- 
mary divisions of the earth is sufficiently clear. In order to 
make these relations visible to the eye and more easily remem- 
bered, we will put them in a tabular form : 

Herons. Gco^p-aphical Eqoivaleut. 

Falffiarctic Ecrope, with north temperate Africa and Asia. 

Ethiopian Africa (south of the Sahara), with Madagascar. 

Oriental Trofical Asia, to Philippines and Java. 

Australian Acstralia, with Pacific islands, Moluccas, etc. 

Nearctic North America, to North Mexico. 

Neotropical South America, with tropical North America and West Indies. 

The following arrangement of the regions will indi(*ate their 
geographical position, and to a considerable extent their relation 
to each other : 

Nearctic Pal-«arctic 

I 

Oriental 
Neo- ETniopiAN 
TROPICAL Australian 



Chap. IV.] EVOLUTION THE KEY TO DISTRIBUTION. 53 



CHAPTER IV. 

EVOLUTION THE KEY TO DISTRIBUTION. 

Importance of the Doctrine of Evolution. — The Origin of New Species. — Variation 
in Animals. — The Amount of Variation in North American Birds. — How New Spe- 
cies Arise from a Variable Species. — Definition and Origin of Genera. — Cause of 
the Extinction of Species. — The Rise and Decay of Species and Genera. — Discon- 
tinuous Specific Areas, why Rare. — ^Discontinuity of the Area o{ Parus palustris, 
— Discontinuity of Emberiza schaniclus, — The European and Japanese Jays. — 
Supposed Examples of Discontinuity among North American Birds. — Distribution 
and Antiquity of Families. — Discontinuity a Proof of Antiquity. — Concluding 
Remarks. 

In the preceding chapters we have explained the general nat- 
ure of the phenomena presented by the distribution of animals, 
and have illustrated and defined the new geographical division 
of the earth which is found best to agree with them. Before we 
go further into the details of our subject, and especially before 
we attempt to trace the causes which have brought about the 
existing biological relations of the islands of the globe, it is ab- 
solutely necessary to have a clear comprehension of the collate- 
ral facts and general principles to which we shall most frequent- 
ly have occasion to refer. These may be briefly defined as the 
powers of dispersal of animals and plants under different condi- 
tions — geological and climatal changes — and the origin and de- 
velopment of species and groups by natural selection. This last 
is of the most fundamental importance, and its bearing on the 
dispersal of animals has been much neglected. We therefore 
devote the present chapter to its consideration. 

As we have already shown in our firet chapter that the distri- 
bution of species, of genera, and of families presents almost ex- 
actly the same general phenomena in varying degrees of com- 
plexity, and that almost all the interesting problems we have to 
deal with depend upon the mode of dispereal of one or other of 
these ; and as, further, our knowledge of most of these groups, 



54 



ISLAND LIFE. 



[Pa«t I. 



in tlio higher auiinals at least, is confined to the Tertiary period 
of geology, it is tlierefore uuneceseary for ub to enter into any 
questions involving tlio origin of more conapreheiisive groups, 
such as classes or orders. This enables ns to avoid most of the 
disputed questions as to the development of animals, and to con- 
fine ourselves to those general principles regulating the origin 
and development of species and genera which were firet laid 
down by Mr. Darwin twenty years ago, and have now come to 
be adopted by naturalists as established propositions in tlie the- 
ory of evolution. 

The Oriijin of New Species. — IIow, then, do new species arise, 
supposing the world to have been, physically, much as wc now 
see it? and what beeomea of them nfler they have arisen? In 
the first place, we must remember that new species can only be 
formed when and where thcro is room for tJicm. If a continent 
is fully stocked with animals, each species being so well adapt- 
ed to its mode of life that it can overcome all the dangers to 
which it is exposed, and maintain on the average a tolerably 
uniform population, then, so long as iio change takes place, no 
new species will arise. For every place or station is supposed 
to -be filled by creatnres perfectly adapted to all surrounding 
conditions, able to defend themselves from all enemies, and to 
obtain food notwithstanding the rivalry of many competitors. 
But such .1 pei-fect balance of organisms nowhere exists upon 
the earth, and probably never has existed. The well-known 
fact that some species are very common, while others are very 
rare, is an almost certain proof that the one is better adapted to 
its position than the other; and this belief is strengthened wlien 
we find the individuals of one spocit^ ranging into difforont 
climates, subsisting on different food, and competing with differ- 
ent seta of animals, while the individuals of another species will 
be limited to a small area beyond which they seem unable to ex- 
tend. When a change occurs, cither of climate or geography, 
some of the small and ill-adapted species will probably diu out 
altogether, and thus leave room for others to increase, or for new 
forms to occupy their places. 

Hut the change will most likely affect even fionrishing species 
in different ways, some benelioialiy, others injnrionsly. Or, 



Chap. IV.] EVOLUTION THE KEY TO DISTRIBUTION. 55 

again, it may affect a great many injuriously, to such an extent 
as to require some change in their structure or habits to enable 
them to get on as well as before. Now "variation" and the 
"struggle for existence" come into play. All the weaker and 
less perfectly organized individuals die out, while those which 
vary in such a way as to bring them into more harmony with the 
new conditions constantly survive. If the change of conditions 
has been considerable, then, after a few centuries, or perhaps 
even a few generations, one or more new species will bo almost 
sure to be formed. 

Variaiion in Animals. — To make this more intelligible to 
those who have not considered the subject, and to obviate the 
difficulty many feel about "favorable variations occurring at the 
right time," it will be well to discuss this matter a little more 
fully. Few persons consider how largely and universally all 
animals are varying. We know, however, that in every genera- 
tion, if we would examine all the individuals of any common 
species, we should find considerable differences, not only in size 
and color, but in the form and proportions of all the parts and 
organs of the body. In our domesticated animals we know this 
to be the case, and it is by means of the continual selection of 
such slight varieties to breed from that all our extremely differ- 
ent domestic breeds have been produced. Think of the differ- 
ence in every limb, and every bone and muscle, and probably in 
every part, internal and external, of the whole body, between a 
greyhound and a bull-dog ! Yet if we had the whole series of 
ancestors of these two breeds before us, we should probably find 
that in no one generation was there a greater difference thau 
now occurs in the same breed, or sometimes even the same litter. 
It is often thought, however, that wild species do not vary suf- 
ficiently to bring about any such change as tliis in the same time ; 
and though naturalists are well aware that this is a mistake, it 
is only recently that they are able to adduce positive proof of 
their opinion. 

T/ie Amount of Variaiion in North American Birds, — An 
American naturalist, Mr. J. A. Allen, has made elaborate obser- 
vations and measurements of the birds of the United States, and 
he finds a wonderful and altogether unsuspected amount of va- 



56 ISLAND LIFE. [Vart L 

riation between individuals of the same species. They differ in 
tlie general tint, and in .the markings and distribution of the 
colors ; in size and proportions ; in the length of the wings, tail, 
bill, and feet; in the length of particular feathers, altering the 
shape of the wing or tail ; in the length of the tarsi and of the 
separate toes ; and in the length, wudth, thickness, and curvature 
of the bill. These variations are very considerable, often reach- 
ing to one sixth or one seventh of the average dimensions, and 
sometimes more. Thus Turdusfascescens (Wilson's thrush) va- 
ried in length of wing from 3.58 to 4.16 inches, and in the tail 
from 3.55 to 4 inches; and in twelve specimens, all taken in 
the same locality, the wing varied in length from 14.5 to 21 per 
cent., and the tail from 14 to 22.5 per cent. In Sialia stalls 
(the blue-bird) the middle toe varied from .77 to .91 inch, and 
the hind toe from .58 to .72 inch, or more than 21.5 per cent, 
on the mean ; while the bill varied from .45 to .56 inch in length, 
and from .30 to .38 inch in width, or about 20 per cent, in both 
cases. In Dendrcsoa coronata (the yellow-crowned warbler) the 
quills vary in proportionate length, so that the first, the second, the 
third, or the fourth is sometimes longest ; and a similar variation of 
the wing involving a change of proportion between two or more 
of the feathers is recorded in eleven species of birds. Color and 
marking vary to an equal extent ; the dark streaks on the under- 
surface of Melospiza weJodia (the American song-sparrow) be- 
ing sometimes reduced to narrow lines, while in other specimens 
they are so enlarged as to cover the greater part of the breast 
and sides of the body, sometimes uniting on the middle of the 
breast into a nearly continuous patch. In one of the small spot- 
ted wood-thrushes, Tiirdus ftiscescenSy the colors are sometimes 
very pale, and the markings on the breast reduced to indistinct 
narrow lines ; while in other specimens the general color is much 
darker, and the breast-markings dark, broad, and triangular. All 
the variations here mentioned occur between adult males, so that 
there is no question of diflferences of age or sex, and the pair last 
referred to were taken at the same place and on the same day.' 

* These facts are taken from a memoir on **The Mammals and Winter Birds of 
Florida/' by J. A. Allen, forming Vol. II., No. 3, of the ** Bulletin of the Museum of 
Comparative Zoology at Uarvaixi College,*' Cambridge, Massachusetts. 



Chap. IV.] EVOLUTION THE KEY TO DISTRIBUTION. 57 

These interesting facts entirely support the belief in the vari- 
ability of all animals in all their parts and organs, to an extent 
amply suflScient for natural selection to work with. We may, 
indeed, admit that these are extreme cases, and that the major- 
ity of species do not vary half or a quarter so much as shown in 
the examples quoted, and we shall still have ample variation 
for all purposes of specific modification. Instead of an extreme 
variation in the dimensions and proportions of the various 
organs of from 10 to 25 per cent., as is here proved to occm*, we 
may assume from 3 to 6 per cent, as generally occurring in the 
majority of species ; and if we further remember that the above 
excessive variations were found by comparing a number of spec- 
imens of each species varying from 50 to 150 only, we may be 
sure that the smaller variations we require must occur in con- 
siderable numbers among the thousands or millions of individu- 
als of which all but the very rare species consist. If, therefore, 
we were to divide the population of any species into three groups 
of equal extent, with regard to any particular character — as length 
of wing or of toes, or thickness or curvature of bill, or strength of 
markings — we should have one group in which the mean or av- 
erage character prevailed with little variation, one in which the 
character was greatly, and one in which it was little, developed. 
If we formed our groups, not by equal numbers, but by equal 
amount of variation, we should probably find, in accordance with 
the law of averages, that the central group, in which the mean 
characteristics prevailed, was much more numerous than the ex- 
tremes; perhaps twice, or even three times, as great as either of 
them, and forming such a series as the following : 10 maximum, 
30 mean, 10 minimum development. In ordinary cases we have 
no reason to believe that the mean characters or the amount of 
variation of a species changes materially from year to year or 
from century to century, and we may therefore look upon the 
central group as the type of the species which is best adapted to 
the conditions in which it has actually to exist. This type will 
therefore always form the majority, because the struggle for ex- 
istence will lead to the continual suppression of the less perfect- 
ly adapted extremes. But sometimes a species has a wide range 
into countries which differ in physical conditions, and then it 



68 



ISLANU LIFE. 



[Pabt I. 



often happens that one or other of the extremes will predomi- 
nate ia a portion of its i-angc. Tliese form loeai varieties ; but 
as they occur mixed with tlie other forms, they are not consid- 
ered to be distinct species, although they may differ from tlie 
other extreme form quite aa mucli as spcuies often do from each 
other. 

now New Species Arise from a Variable Specie«. — It is now 
very easy to understand how, from such a variable species, one 
or more new species may arise. Tlie peculiar physical or organ- 
ic conditions that render one part of the area better adapted to 
an extreme form may become intensified, and the most extreme . 
variations tlius having the advantage, they M'ill multiply at the 
expense of the rest. If the change of conditions spreads over 
the whole area occupied by the species, this one extreme form 
will replace tho others; while if the area should be cut in two 
by subsidence or elevation, tho conditions of the two parts may 
be modified in opposite directions, so aa to be each adapted to 
one extreme form; in whicli case the original type will become 
extinct, being replaced by two species, each formed by a combi- 
nation of certain exti'eme characters which had before existed 
in some of its varieties. 

The changes of conditions which lead to such selection of va- 
rieties ai-e very divcree in nature, and new species may thus be 
formed, diverging in many ways from the original stock. The 
climate may ehauge from moist to dry, or the reverse, or tho 
temperature may increase or diminish for long periods, in cither 
case requiring a corresponding change of constitution, of cover- 
ing, of vegetable or of insect food, to be met by the selection of 
variations of color or of swiftness, of length of bill or of strength 
of claws. Again, competitors or enemies may arrive from other 
regions, giviug the advantage to snclt varieties as can cliangc 
their food, or by swifter flight or greater wariness can escape 
their new foes. We may thus easily understand Low a series of 
changes may occur at distant intervals, each leading to the se- 
lection and preservation of a special set of vtiriations, and thus 
what was a single species may become transformed into a group 
of allied species differing from each other in u variety of ways, 
just as we iind them in nature. 



Chap. IV.] EVOLUTION THE KEY TO DISTRIBUTION. 59 

Among these species, however, there will be some which will 
have become adapted to very local or special conditions, and 
will therefore be comparatively few in number and confined to 
a limited area ; while others, retaining the more general charac- 
ters of the parent form, but with some important change of 
stnicture, will be better adapted to succeed in the struggle for 
existence with other animals, will spread over a wider area, and 
increase so as to become common species. Sometimes these will 
acquire such a perfection of organization by successive favorable 
modifications that they will be able to spread greatly beyond 
the range of the parent form. They then become what are 
termed dominant species, maintaining themselves in vigor and 
abundance over very wide areas, displacing other species with 
which they come into competition, and, under still further 
changes of conditions, becoming the parents of a new set of di- 
verging species. 

Definition and Origin of Ge)iera, — As some of the most im- 
portant and interesting phenomena of distribution relate to gen- 
era rather than to single species, it will be well here to explain 
what is meant by a genus, and how genera are supposed to arise. 

A genus is a group of allied species which differs from all 
other groups in some well-marked characters, usually of a struct- 
ural rather than a superficial nature. Species of one genus usu- 
ally differ from each other in size, in color or marking, in the 
proportions of the limbs or other organs, and in the form and 
size of such superficial appendages as horns, crests, manes, etc. ; 
but they generally agree in the form and stnicture of important 
organs, as the teeth, the bill, the feet, and the wings. When 
two groups of species differ from each other constantly in one 
or more of these latter particulars, they are said to belong to dif- 
ferent genera. AVe have already seen that species vary in these 
more important as well as in the more superficial characters. 
If, then, in any part of the area occupied by a species some 
change of habits becomes useful to it, all such structural varia- 
tions as facilitate the change will be accumulated by natural se- 
lection ; and when they have become fixed in the proportions 
most beneficial to the animal, we shall have the first species of 
a new genus. 



ISLAND LIFE. 



[Pa-t I. 



A creature which has been thus nioJified in importaiit charac- 
ters will be a now tyiie, special! j adapted to fill its place in the 
economy of nature. It will almost certainly have arisen from 
an extensive or dominant group, because only such are sufficient- 
ly rich in individuals to afford an ample supply of the necessary 
variations, and it will inherit tlio vigor of constitntion and adapt- 
ability to a wide nuigo of conditions which gave success to its 
ancestors. It will thercfom have every chance in its favor in 
the struggle for existence; it may spread widely and displace 
many of its nearest allies, and in doing so will itself become 
modified superficially and become the parent of a number of 
subordinate species. It will now have become a dominant genus, 
occupying an entire continent, or perhaps even two or more con- 
tinents, spreading in every direction till it comes in contact with 
competing forms better adapted to the different environments. 
Such a genus may continue to exist during long geological 
epochs; but the time will generally come when eitlier physical 
changes, or competing forms, or new enemies are too much for 
it, and it begins to lose its supremacy. First one, then another, 
of its component species will dwindle away and become extinct, 
till at last only a few species remain. Sometimes these soon 
follow the others, and the whole genus dies out, as thousands of 
genera have died out during the long course of the earth's life- 
history; but it will also sometimes happen that a few species 
will continue to maintain themselves in areas whei-o they are re- 
moved from the intlnences that exterminated their fellows. 

Cause of the Jirtinction of Sjwcies. — There is good reason to 
believe that the most effective agent in the extinction of spcciea 
is the preesiue of otlier species, whether as enemies or merely as 
eompelitora. If tlierefore any portion of the earth is cut ofE 
from the influx of new or more highly organized animals, we 
may there expect to find the remains of groups which have else- 
where become extinct. In islands which have been long sepa- 
rated from their parent continents those conditions are exactly 
fulfilled, and it is in such that wc find the most striking examples 
of the preservation of fragments of primeval gronpa of animals, 
often widely separated from each other, owing to their having 
been jirescrved at remote portions of the area of the once wide- 



Chap. IV.] EVOLUTION THE KEY TO DISTRIBUTION. 61 

spread parental group. There are many other ways in which 
portions of dying-out groups jnay be saved. Nocturnal or sub- 
terranean modes of life may save a species from enemies or com- 
petitors, and many of the ancient types still existing have such 
habits. The dense gloom of equatorial forests also affords means 
of concealment and protection, and we sometimes find in such 
localities a few remnants of low types in the midst of a general 
assemblage of higher forms. Some of the most ancient types 
now living inhabit caves, like the Proteus ; or bury themselves 
in mud, like the Lepidosiren ; or in sand, like the Amphioxus, 
the last being the most ancient of all vertebrates; while the 
Galeopithecus and Tarsius of the Malay Islands, and the potto 
of West Africa, survive amidst the higher mammalia of the Asi- 
atic and African continents, owing to their nocturnal habits and 
concealment in the densest forests. 

The Rise and Decay of Species and Genera, — The preceding 
sketch of the mode in which species and genera have arisen, 
have come to maturity, and then decay, leads us to some very 
important conclusions as to the mode of distribution of animals. 
When a species or a genus is increasing and spreading, it neces- 
sarily occupies a continuous area which gets larger and larger 
till it reaches a maximum ; and we accordingly find that almost 
all extensive groups are thus continuous. When decay com- 
mences, and the group, ceasing to be in harmony with its envi- 
ronment, is encroached upon by other forms, the continuity may 
frequently be broken. Sometimes the outlying species may be 
the first to become extinct, and the group may simply diminish 
in area while keeping a compact central mass ; but more often 
the process of extinction will be very irregular, and may even 
divide the group into two or more disconnected portions. This 
is the more likely to be the case because the most recently 
formed species, probably adapted to local conditions, and there- 
fore most removed from the general type of the group, will 
have the best chance of surviving, and these may exist at sever- 
al isolated points of the area once occupied by the whole group. 
We may thus understand how the phenomenon of discontinuous 
areas has come about, and we may be sure that when allied spe- 
cies or varieties of the same species are found widely separated 



62 ISLAND LIFE. [Pabt I. 

from each other, they wore onec connected by intervening forms 
or by each extending till it overlapped the other's area. 

Discontinuous iSpccijiv Areas, why Rare. — But although dls- 
contitiiions generic ureas, or the separation from each other «f 
species whose ancestore must onca h«vc occnpied conterminous 
or overlapping areas, are of frequent occurrence, yet undoubted 
cases of discontinnous specific areas are very rare, except, as al- 
ready stittod, when one portion of a speeies inhabits an island. 
A few examples among mammalia Lave been referred to in our 
first chapter, but it may be said that these are examples of the 
■sary comuion phenomenon of a species being only fonnd in the 
station for which its organization adapts it; so that forest or 
marsh or mountain animals are of courae only found where there 
are forests, marshes, or mountaina. This may be true ; and when 
the separate forests or mountains inhabited by ihe same species 
arc not far apart, there is little that needs explanation : but in 
one of tlie cases referred to there was a gap of a thousand miles 
between two of the areas occupied by the species ; and this being 
too far for the animal to traverse through an uncongenial terri- 
tory, we are forced to the conclnsiou that it must at some former 
period, and under different conditions, have occupied a consider- 
able portion of the intervening area. 

Among birds such cases of specific discontinuity are very rare, 
and hardly ever qnite satisfactory. This may be owing to birds 
being more rapidly infiiienccd by changed conditions, so that 
when a species is divided tho two portions almost always be- 
come modified into varieties or distinct species; while auotlicr 
reason may be that their powers of flight cause them to occupy, 
on tho average, wider and less precisely defined areas than do 
the speeios of mammalia. It will be interesting, therefore, to 
examine the few cases on record, as we shall thereby obtain ad- 
ditional knowledge of tho steps and processes by which tho dis- 
tribution of varieties and species has been brought about. 

Disconfinuitij of the Area of Paruspalustris. — Mr. Seebohm, 
who has travelled and collected in Europe, Siberia, and India, 
and possesses extensive and accurate knowledge of Paleearctic 
birds, has recently called attention to tho varieties and suh-spc- 
cies of tho marsh tit [Parus palustns)y of which he has exam- 



Chap. IV.] EVOLUTION THE KEY TO DISTRIBUTION. 63 

ined numerous specimens ranging from England to Japan.* The 
curious point is that those of Southern Europe and of China are 
exactly alike, while all over Siberia a very distinct form occurs, 
the sub-species P. horealu. In Japan and Kamtschatka other 
varieties are found, which have been named respectively -P. Ja- 
ponieus and P. CamischcUJcensis. Now it all depends upon these 
forms being classed as sub-species or as true species whether this 
is or is not a case of discontinuous specific distribution. If Pa- 
rus horealin is a distinct species from Partis palustris^ as it is 
reckoned in Gray's " Hand List of Birds," and also in Sharpe and 
Dresser's "Birds of Europe," then Panes palustris has a most re- 
markable discontinuous distribution as shown in the accompany- 
ing map, one portion of its area comprising Central and South 
Europe and Asia Minor, the other an undefined tract in Northern 
China, the two portions being thus situated in about the same 
latitude and having a very similar climate, but with a distance 
of about four thousand miles between them. If, however, these 
two forms are reckoned as sub-species only, then the area of the 
species becomes continuous, while only one of its varieties or 
sub-species has a discontinuous area. It is a curious fact that P, 
palustris and P. horealis are found together in Southern Scan- 
dinavia and in some parts of Central Europe, and are said to differ 
somewhat in their note and their habits, as well as in coloration. 
Discontinuity of Emheriza schosntches. — The other case is that 
of our reed-bunting {Emheriza schoeniclus)^ which ranges over 
almost all Europe and AVestern Asia as far as the Yenisei val- 
ley and Northwest India. It is then replaced by another smaller 
species, E.passerina^ which ranges eastward to the Lena River, 
and in winter as far south as Amoy in China; but in Japan the 
original species appears again, receiving a new name {E.pyrrhu- 
lina)y but Mr. Seebohm assures us that it is quite indistinguish- 
able from the European bird.' Although the distance between 
these two portions of the species is not so great as in the last ex- 
ample, being about two thousand miles, in other respects the 
case is a most satisfactory one, because the forms which occupy 
the intervening space are recognized by Mr. Seebohm himself 
as undoubted species. 

* Ibis, 1879, p. 82. « litis, 1870, p. 40. 



ISLAND LlPt:. 



[pAar I. 



The JCuropean and Jajtanesf Jayg. — Anotlicr ease somewhat 
reaciubling tlint of tlio inareli tit is afforded by the European 
and Japanese jays (6^</rrn^««y/(i«(/«'-*K« and O.Jajionicus). Our 
common jay inhabits the whole of Europe except the extreme 
north, but is not known to extend anywhei-e into Asia, where it 
16 represented by several quite distinct species. (See Map, fron- 
tispiece.) Gut the great central island of Japan is inhabited by 
a jay {G. Japonicm) which is very like ours, and was formerly 
classed as a Biibspeeics only, in which case onr jay would be con- 
sidered to have a discontinuous distribution. But the specific 
distinctness of the Japanese bird is now universally admitted, 
and it is certainly a very remarkable fact that among the twelve 
epecics of jays which togetlier range over all temperate Europe 
and Asia, one which is bo closely allied to onr English bii'd should 
be found at the remotest possible point from it. Looking at tlio 
map exhibiting the dislribntion of the several species, we eau 
hardly avoid the conclusion that a bird very like our jay once 
occupied the whole area of tlie genus, that in various parts of 
Asia it became gi-adually iiioditied into a variety of distinct spe- 
cies in the maimer already explained, a remnant of the original 
type being preserved almost unchanged in Japan, owing prob- 
ably to favorable conditions of climate and protection from com- 
peting forms. 

SuppcMtnl Ei^amph'8 of Di«coniintiili/ among XoHh American 
liirdn. — In North America the eastern and M^eatern provinces 
are so difEcrcnt in climate and vegetation, and are besides sep- 
arated by such remarkable physical barriers — the arid central 
plains and the vast ranges of the Rocky Mountains and Sierra 
Nevada — that we can hardly ex[)ect to Hnd species whose areas 
may bo divided maintaining their identity, ToM-ards the north, 
however, the above-named barrio's disappear, the forests being 
almost continuuns from east to west, while the mountain-range 
is broken up by passes and valleys. It tlius happens that must 
species of birds which inhabit both the eastern and western 
coasts of the North American continent have maintained their 
continuity towards tho north, while even when difforentiutcd into 
two or more allied species their areas are often conterminous or 
overlapping. 



CfiAP.IV.] EVOLUTION THE KEY TO DISTHIBUTION. 65 

Almost the only bird that seems to have a really discontinu- 
ous range is the species of wren Thryothoru^ Bewickii, of which 
the type-form ranges from the east coast to Kansas and Minne- 
sota, while a longer-billed variety is found in the wooded parts 
of California and as far north as Puget Sound. If this really 
represents the range of the species, there remains a gap of about 
one thousand miles between its two disconnected areas. Other 
cases are those of the greenlet, Vireo8ylvia gilvus^ of the Eastern 
States, and its variety V. Swahisonii^ of the Western ; and of the 
purple rediBnch, Carpodaous purpureuSy with its variety C. Cali- 
f amicus. But, unfortunately, the exact limits of these varieties 
are in neither case known ; and though each one is characteristic 
of its own province, it is possible they may somewhere become 
conterminous, though in the case of the redfinches this does not 
seem likely to be the fact. 

In a later chapter we shall have to point out some remarkable 
cases of this kind where one portion of the species inhabits an 
island ; but the facts now given are sufficient to prove that the 
discontinuity of the area occupied by a single homogeneous spe- 
cies, by two varieties of a species, by two well-marked sub-spe- 
cies, and by two closely allied but distinct species, are all differ- 
ent phases of one phenomenon — the decay of ill-adapted and 
their replacement by better-adapted forms, under the pressure 
of a change of conditions either physical or organic. AVo may 
now proceed with our sketch of tlie mode of distribution of 
higher groups. 

Distribution aiid Antiquity of Families, — Just as genera are 
groups of allied species distinguished from all other groups by 
some well-marked structural characters, s>o families are groups 
of allied genera distinguished by more marked and more impor- 
tant characters, which are generally accompanied by a peculiar 
outward form and style of coloration, and by distinctive habits 
and mode of life. As a genus is usually more ancient than any 
of the species of which it is composed, because during its growth 
and development the original rudimentary species becomes sup- 
planted by more and more perfectly adapted forms, so a family 
is usually older than its component genera, and during the long 
period of its life-history may have survived many and great ter- 

5 



ISLAND LIFE. 



[I'AI 



:I- 



restrial and organic clianges. Many families of llie liigber ani- 
nials liaVQ now ati almost world-wide extension, or at least range 
over several continents; and it seems probable tbat nil families 
wliieli liavG eiirvived long enougli to develop a considerable va- 
riety of generic and epeeilie forms bave also at one time or other 
occupied an extensive area. 

Viseoniinuiti/ a Proof of AntiquUy. — Discontinuity will 
llierefore be an indication of antiquity; and tlie more widely 
the fragments are scattered, the more ancient we may usnally 
presnme tbe parent gronp to lie. A striking example is fur- 
nished by tbe strange reptilian fisbes forming the order or enb- 
order Dipnoi, which includes tbe Lepidosiren and its allies. 
Only three or four living species are known, and these inhabit 
tropical rivers gitnated in the remotest continents. The Ja-jjIiIo- 
siren- paradoxa is only known from the Amazon and some oth- 
er South American rivers. An allied species, I^j/idoairen an- 
ned^ts, eometimea placed in a distinct genus, inhabits tbe Oam- 
bia in West Africa; while the recent discovery in Eastern Ans- 
tralia of tbe Ceratodue, or mud-fisb, of Queensland adds another 
form to the same isolated group. Numerous fossil teeth long 
known from thcTriassic. beds of this country, and also found in 
Germany and India in beds of tbe same age, agree so closely 
with those of tbe living Ceratodus that both are referred to tbe 
same gends. No more recent traces of any such animal bave 
been discovered, bnt the Carboniferous Ctenodna and tbe De- 
vonian Diptepiis evidently belong to the same gronp, while in 
North America the Devonian rocks have yielded a gigantic al- 
lied form which has been named Hcliodns by Professor New- 
berry. Tlins an enurmons range in time is accompanied by a 
very wide and scattered distribution of the existing species. 

Whenever, tlicrefore, we find two or more living genera he- 
longing to the same family or order, lint not very closely allied 
to each other, we may bo sure tbat they arc the remnants of 
ft once extensive group uf genera; and if we tind tliem now 
isolated in remote parts of the globe, the natural inference is 
that the family of which they are frngnients once had an area, 
embracing the countries in which they are found. Yet this 
Biniple and very obvious explanation has rarely been adopted 



Chap. IV.] EVOLUTION THE KEY TO DISTRIBUTION. 67 

by naturalists, who Lave instead imagined clianges of land and 
sea to aflford a direct passage from the one fragment to the 
other. If there were no cosmopolitan or very wide-spread fam- 
ilies still existing, or even if such cases were rare, there would 
be some justiiBcation for such a proceeding ; but as about one 
fourth of the existing families of land mammalia have a range 
extending to at least three or four continents, while many which 
are now represented by disconnected genera are known to have 
occupied intervening lands or to have had an almost continuous 
distribution in Tertiary times, all the presumptions are in favor 
of the former continuity of the group. We have also in many 
cases direct evidence that this former continuity was eflfected 
by means of existing continents, while in no single case has it 
been shown that such a continuity was impossible, and that it 
either was or must have been eflfected by means of continents 
now sunk beneath the ocean. 

C<yncludi7i/f Remarks, — ^When writing on the subject of dis- 
tribution, it usually seems to have been forgotten that the theory 
of evolution absolutely necessitates the former existence of a 
whole series of extinct genera filling up tlie gap between the 
isolated genera which in many cases now alone exist ; while it 
is almost an axiom of "natural selection" that such numerous 
forms of one type could only have been developed in a wide 
area and under varied conditions, implying a great lapse of 
time. In our succeeding chapters we shall show that the known 
and probable changes of sea and land, the known changes of 
climate, and the actual powers of dispersal of the diflferent groups 
of animals were such as would have enabled all the now discon- 
nected groups to have once formed parts of a continuous series. 
Proofs of such former continuity are continually being obtained 
by the discovery of allied extinct forms in intervening lands; 
but the extreme imperfection of the geological record as re- 
gards land animals renders it unlikely that this proof will bo 
forthcoming in the majority of cases. The notion that if such 
animals ever existed their remaius would certainly be found is 
a snpei'stition which, notwithstanding the eflforts of Lyell and 
Darwin, still largely prevails among naturalists; but until it is 
got rid of, no true notions of the former distribution of life 
upon the earth can be attained. 



68 ISLAND LIFE. [Pabt L 



CHAPTER V. 

THE POWERS OF DISPERSAL OF ANIMALS AND PLANTS. 

Statement of the General Question of Dispei'snl. — The Ocean as a Barrier to the 
Dispersal of Mammals. — The Dispersal of Birds. — ^IMie Dispersal of Reptiles. — 
The Dispersal of Insects. — The Dispersal of Land Mollusca. — Great Antiquity of 
Land Shells. — Causes Favoring the Abundance of Land Shells. — The Dispersal 
of Plants. — Special Adaptability of Seeds for Dispersal. — Birds as Agents in the 
Dispersal of Seeds. — Ocean Currents as Agents in Plant-dispersal. — Dispersal 
along Mountain-chains. — Antiquity of Plants as Affecting their Distribution. 

In order to nnderstaud tlie many curious anomalies we meet 
with in studying the distribution of animals and plants, and to 
be able to explain how it is that some species and genera have 
been able to spread widely over the globe, while others are con- 
fined to one hemisphere, to one continent, or even to a single 
mountain or a single island, we must make some inquiry into 
the different powers of dispersal of animals and plants, into the 
nature of the barriers that limit their migrations, and into the 
character •of the geological or climatal changes which have fa- 
vored or checked such migrations. 

The first portion of the subject — that which relates to the 
various modes by which organisms can pass over wide areas of 
sea and land — has been fully treated by Sir Charles Lyell, by 
Mr. Darwin, and many other writers, and it will be only neces- 
sary here to give a very brief notice of the best-known facts on 
the subject, which will be further referred to when we come to 
discuss the particular cases that arise in regard to the faunas 
and floras of remote islands. But the other side of the question 
of dispersal — that which depends on geological and climatal 
changes — is in a far less satisfactory condition; for, though 
much has been written upon it, the most contradictory opinions 
still prevail, and at almost every step we find ourselves on the 
battle-field of opposing schools in geological or physical science. 



Chap. v.] DISPERSAL OF ANIMALS AND PLANTS. 69 

As, however, these questions lie at the very root of any general 
solution of the problems of distribution, I have given much 
time to a careful examination of the various theories that have 
been advanced, and the discussions to which they have given 
rise ; and have arrived at some definite conclusions which I vent- 
ure to hope may serve as the foundation for a better comprehen- 
sion of these intricate problems. The four chapters which follow 
this are devoted to a full examination of these profoundly interest- 
ing and important questions, after which we shall enter upon our 
special inquiry — ^the nature and origin of insular faunas and floras. 
The Ocean as a BarAer to the Dispersal of Mammals. — A 
wide extent of ocean forms an almost absolute barrier to the dis- 
persal of all land animals, and of most of those which are aerial, 
since even birds cannot fly for thousands of miles without rest 
and without food, unless they are aquatic birds which can find 
both rest and food on the surface of the ocean. We may be 
sure, therefore, that without artificial help neither mammalia nor 
land birds can pass over very wide oceans. The exact width 
they can pass over is not determined, but we have a few facts to 
guide us. Contrary to the common notion, pigs can swim very 
well, and have been known to swim over five or six miles of sea, 
and the wide distribution of pigs in the islands of the Eastern 
Hemisphere may be due to this power. It is almost certain, how- 
ever, that they would never voluntarily swim away from their 
native land, and if carried out to sea by a flood they would cer- 
tainly endeavor to return to the shore. We cannot, therefore, 
believe that they would ever swim over fifty or a hundred miles 
of sea, and the same may be said of all the larger mammalia. 
Deer also swim well, but there is no reason to believe that they 
would venture out of sight of land. With the smaller, and es- 
pecially with the arboreal, mammalia there is a much more ef- 
fectual way of passing over the sea, by means of floating trees, 
or those floating islands which are often formed at the mouths 
of great rivers. Sir Charles Lyell describes such floating islands 
which were encountered among the Moluccas, on which trees 
and shrubs were growing on a stratum of soil, which even formed 
a white beach round the margin of each raft. Among the Phil- 
ippine Islands similar rafts with trees growing on them have 



ISLAND LIFE. 



[Pa«t 1. 



been setu after hurricanes; and it is easy tu uudcrstaiid liow, if 
the sea were tolerably calm, euch a mft might be carried along 
by a current, aided by the wind acting on the trees, till, after a 
paseage of several weeks, it miglit arrive safely on the shores of 
some land hundreds of miles awny from its starting-point. Such 
small animals as squirrels and mice might have been carried 
away on the trees which formed part of such a raft, and might 
thus colonize a new island; though, as it would require a pair 
of the same species to bo carried away together, sncli accidents 
would no doubt bo rare. Insects, Iiowever, and land shells would 
almost certainly he abundant on such a raft or island, and in this 
way we may account for the wide dispersal of many species of 
both these groups. 

Notwithstanding the occasional action of such causes, wc can- 
not suppose that they have been etfectivc in the dispersal of 
nianiiualia as a whole ; and whenever we find that a considerable 
number of the mammals of two countries e.\hibit distinct niarks 
of relationship, we may be sure that an actual land connection, 
or, at all events, an approach to within a very few miles of each 
other, has at one time existed. IJut a considerable number of 
identical mammalian families, and even genei-a, are actually 
found in all the great continents, and the present distribution 
of land upon tlie globe renders it easy to see how they have 
been able to disperse themselves so widely. All the great land 
masses I'adiate from the arctic regions as a eoiumon centre, the 
only break being at Behring Strait, whicli is so shallow that a 
rise of less than a tliousand feet would form a broad isthmus 
connecting Asia and America as far south as the parallel of 00° 
N. Continnity of land, therefore, may be said to exist already 
for all parts of the world (except Australia and a number of 
large islands, which will he considered separately), and we liavo 
thus no difficulty in the way of that former wide diffusion of 
many groups which we maintain to be the only explanation of 
most anomalies of distribution otlier than such as may be con- 
nected with nnsuitability of climate. 

Tho DUpersal of Birds. — WJicrever mammals can migrate, 
other vertebrates can generally follow with even greater facility. 
Birds, liaving the power of flight, can pass over wide arms of 



Chap, v.] DISPERSAL OF ANIMALS AND PLANTC. 71 

the sea, or even over extensive oceans, when these are, as in the 
Pacific, studded with islands to serve as resting-places. Even 
the smaller land birds are often carried by violent gales of wind 
from Europe to the Azores, a distance of nearly a thousand 
miles, so that it becomes comparatively easy to explain the ex- 
ceptional distribution of certain species of birds. Yet on the 
whole it is remarkable how closely the majority of birds follow 
the same laws of distribution as mammals, showing that they 
generally require either continuous land or an island-strewn sea 
as a means of dispersal to new homes. 

The Dispersal of lieptiles. — Reptiles appear at first sight to 
bo as much dependent on land for their dispersal as mammalia ; 
but they possess two peculiarities which favor their occasional 
transmission across the sea — the one being their greater tenacity 
of life, the other their oviparous mode of reproduction. A large 
boa-constrictor was once floated to the island of. St. Vincent 
twisted round the trunk of a cedar-tree, and was so little injured 
by its voyage that it captured some sheep before it was killed. 
The island is nearly two hundred miles from Trinidad and the 
coast of South America, whence it almost certainly came.* 
Snakes are, however, comparatively scarce on islands far from 
continents, but lizards are often abundant; and though these 
might also travel on floating trees, it seems more probable that 
there is some as yet unknown mode by which their eggs are 
safely, though perhaps very rarely, conveyed from island to isl- 
and. Examples of their peculiar distribution will be given when 
we treat of the fauna of some islands in which they abound. 

The Dispersal of Amphibia and Fresh - water Fishes, — The 
two lower groups of vertebrates, amphibia and fresh-water fishes, 
possess special facilities for dispersal, in the fact of their eggs 
being deposited in water, and in their aquatic or semi-aquatic 
habits. They have another advantage over reptiles in being ca- 
pable of flourishing in arctic regions, and in the power possessed 
by their eggs of being frozen without injury. They have thus, 
no doubt, been assisted in their dispersal by floating ice, and by 
that approximation of all the continents in high northern lati- 

> Lyeirs "Principles of Geology," II., p. 309. 



72 ISLAND LIFE. 

tudes Tvliicli lias been tlio chief agent in producing tlio gencrHi 
uniformity in the animal prodiictione of the globe. Some genera 
of Jlatruchia have almost a world-wide distribtition ; wlule the 
Tailed Batrachia, such as the newts and salamanders, are almost 
entirely confined to the Northern Hemisphere, some of the gen- 
era spreading over the whole of the north temperate zone. Fresh- 
water fishes have often a very wide range, the same species being 
Bometinies found in all the rivers of a continent. This is no 
doubt chiefly dno to the ivant of permanence in river basins, es- 
pecially in their lower portions, where streams belonging to dis- 
tinct systems often approach each other and may bo made to 
change their course from one to the other basin by very elight 
elevations or depressions of the land. Hurricanes and water- 
spouts also often carry considerable quantities of water fi'om 
ponds and rivers, and thus disperse eggs and even small fishes. 
As a rule, however, the same species are not often found in 
countries separated by a considerable extent of sea, and in the 
tropics rarely the earae genera. The exceptions are in the colder 
regions of the earth, where the transporting power of ico may 
have come into play. High ranges of monnlains, if continuous 
for long distances, rarely have the same species of fish in the 
rivers on their two sides. Where exceptions occur, it is often 
due to the great antiquity of the group, which has survived so 
many changes in physical geography that it has been able, step 
by step, to reach countries which are separated by barriers im- 
passable to more recent types. Yet another and more eflicient 
explanation of the distribution of this group of animals is the 
fact that many families and genera inhabit both fi-esh and salt 
water; and there Is reason to believe that many of the fishes 
now inhabiting the tropical rivers of both liemisphcres have 
arisen from allied marine fonus becoming gradually modified 
for a life in fresh water. By some of these various causes, or a 
combination of them, most of the facts in the distribution of 
fishes can be explained without nincli difficulty. 

The Dhpersal of Insects. — In the enormous group of insects 
the means of dispei'eal among land animals reach their maxi- 
mum. Many of them Lave great powers of tliglit, and from 
their extreme lightness they can be carried immense distances 



Chap, v.] DISPERSAL OF ANIMALS AND PLANTS. 73 

by gales of wind. Others can survive exposure to salt water 
for many days, and may thus be floated long distances by ma- 
rine currents. The eggs and larvae often inhabit solid timber, 
or lurk under bark or in crevices of logs, and may thus reach 
any countries to which such logs arc floated. Another impor- 
tant factor in the problem is the immense antiquity of insects, 
and the long persistence of many of the best-marked types. 
The rich insect fauna of the Miocene period in Switzerland con- 
sisted largely of genera still inhabiting Europe, and even of a 
considerable number identical, or almost so, with living species. 
Out of 156 genera of Swiss fossil beetles, no less than 114 are 
still living; and the general character of the species is exactly 
like that of the existing fauna of the Northern Ileniisphere in a 
somewhat more southern latitude. There is, therefore, evidently 
no difficulty in accounting for any amount of dispersal among 
insects ; and it is all the more surprising that with such powers 
of migration they should yet be often as restricted in their range 
as the reptiles or even the mammalia. The cause of this won- 
derful restriction to limited areas is undoubtedly the extreme 
specialization of most insects. They have become so exactly 
adapted to one set of conditions that when carried into a new 
country they cannot live. Many can only feed in the larva state 
on one species of plant ; others are bound up with certain groups 
of animals on which they are more or less parasitic. Climatal 
influences have a great effect on their delicate bodies; while, 
however well a species may be adapted to cope with its enemies 
in one locality, it may be quite unable to guard itself against 
those which elsewhere attack it. From this peculiar combina- 
tion of characters it happens that among insects are to be found 
examples of the widest and most erratic dispersal and also of the 
extremest restriction to limited areas ; and it is only by bearing 
these considerations in mind that we can find a satisfactory ex- 
planation of the many anomalies we meet with in studying their 
distribution. 

The Dispersal of Land MoUusca. — The only other group of 
animals we need now refer to is that of the air-breathing mol- 
lusca, commonly called land shells. These are almost as ubiqui- 
tous as insects, though far less numerous ; and their wide distri- 



ISLAND LlfE. 



[Pakt I. 



bution ia by no moans so easy to expluiit. TIig genera bnve 
usuiilly a very ^-ide, fliid often a cosmopolitan, range, while the 
species are rather restricted, and Eometimes wonderfnlly bo. 
Kot only do single islands, however smnll, often possess peculiar 
species of Iniid sliells, but sometimes single monntains or valleys, 
or even a patticiilar mountain-side, possess species or varieties 
found nowhere else upon the globe. It is pretty certain that 
tbey have no means of passing over the sea but such as ai-e very 
rare and exceptional. Some which possess an operculum, or 
which close the mouth of the shcl! with a diaphragm of secroted 
mucus, may float across narrow anus of the sea. especially when 
protected in the crevices of logs of timber ; while in the young 
state when attached to leaves or twigs they may be carried long 
distances by hurricanes.' Owing to their exceedingly slow mo- 
tion, their powers of voluntary dispersal, even on land, iii"e very 
limited, and this will explain the extreme restriction of their 
range in many cases. 

Great Antiquity of Laiul S/ielfs. — The clew to the almost uni- 
versal distribution of the several families and of many genera 
is to be found, however, in their immense antiquity. In the 
PlioceuQ and Miocene formations most of the land shells arc 
either identicitl with living species or closely allied to them; 
while even in the Eocene almost all are of living genera, and 
ono Britisli Kocene fossil still lives in Te.\as. Strange to say, 
no true land shells havo been discovered in the Secondary for- 
mations ; but they must certainly have abounded, for in the far 
more ancient Paltpozoic coal measures of Nova Scotia two spe- 
cies belonging to the living genera I'upa and Zonites have been 
found in corisiderable abundance. 

Lund shells havo therefore survived all the revolutions the 
earth has undergone since Palaeozoic times. They have been 

' Mr. Dnrwin fuund ihnt Ihe Inrgo Helix pomaiia lived ofier immersion in Bcn- 
wiuor fur iweoiy dnyt, It ia hnnlly likely ihat lliis i* ilie exirema limit of llidr 
powers of oiidurnllci;, but «ren tliii would nitow of tlicir being flonled many linndred 
mllM nt u ■ti'clcli ; and if wc lugijiuse the Bliell to ba pnrtiatly |imiecled in iJie creviee 
nf fl log of wood, nnd to be lliua ont of wntw in cnitn wenllier, tlis distance might 
exieml to it tbousnnd miles or more. The oggi of frwh-waler mollniea nre known 
lo ntinrli ilicmsi-lvM to tlia foet of oquntlc liirda, and ihi« is mpposod to neconnt for 
llieir very wiile ditTuiiun. 




Chap, v.] DISPERSAL OF ANIMALS AND PLANTS. 73 

able to spread slowly but surely into every land that has ever 
been connected with a continent, while the rare chances of trans- 
fer across the ocean, to which we have referred as possible, have 
again and again occurred during the almost unimaginable ages 
of their existence. The remotest and most solitary of the isl- 
ands of the mid-ocean have thus become stocked with them, 
though the variety of species and genera bears a direct relation 
to the facilities of transfer, and the shell fauna is never very 
rich and varied, except in countries which have at one time or 
other been united to some continental land. 

Causes FavorirKj the Ahxuidan^e of Land Shells. — The abun- 
dance and variety of land shells arc also, more than those of any 
other class of animals, dependent on the nature of the surface 
and the absence of enemies; and where these conditions are 
favorable, their forms are wonderfully luxuriant. The first con- 
dition is the presence of lime in the soil, and a broken surface 
of country with much rngged rock offering crevices for conceal- 
ment and hybernation. The second is a limited bird and mam- 
malian fauna, in which such species as are especially shell-eaters 
shall be rare or absent. Both these conditions are found in cer- 
tain largo islands, and pre-eminently in the Antilles, w^hich pos- 
sess more species of land shells than any single continent. If we 
take the whole globe, more species of land shells are found on 
the islands than on the continents — a state of things to which no 
approach is made in any other group of animals whatever, but 
which is perhaps explained by the considerations now suggested. 

The Dispersal of Plants, — The ways in which plants are dis- 
persed over the earth, and the special facilities they often pos- 
sess for migration, have been pointed out by eminent botanists, 
and a considerable space might bo occupied in giving a sum- 
mary of w^hat has been written on the subject. In the present 
work, however, it is only in two or three chapters that I discuss 
the origin of insular floras in any detail ; and it will therefore 
l)e advisable to adduce any special facts when they are required 
to support the argument in particular cases. A few general re- 
marks only will tlierefore be made here. 

Special AdaptabUity of Seeds for Dispersal. — Plants possess 
many great advantages over animals as regards the power of 



70 ISLAND LIFE. [I'*iir !. 

dispersal, since they are all propagated by seeds or spores, wLicli 
are hardier than the eggs of even insects, and retain their vital- 
ity for a much longer time. Seeds may lie dormant for many 
years and then vegetate, while they endure extremes of lieat, of 
cold, of drought, or of moisture which would almost always be 
fatal to animal germs. Among the causes of tlie dispersal of 
seeds J)e Candollo enumerates the wind, rivers, ocean currents, 
icebergs, birds and other animals, and liiiman agency. Great 
MUinbers of seeds are specially adapted for transport by one or 
other of these agencies. Many are very light and have winged 
appendages, pappus, or down, which enables theni to be carried 
enormous distitiiccs. It is true, as De Candolle remarks, that 
we have no actual proofs of their being so carried; but this 
is not surprising when we consider how small and inconspic- 
uous most seeds are. Supposing every year a million seeds 
were brought by the wind to the British Isles from the Con- 
tinent, this would be only ten to a square mile, and the ob- 
servation of a lifetime might never detect one ; yet a hun- 
dredth part of this number would serve in a few centuries to 
stock an island like Britain with a gi-eat variety of Continental 
plants. 

When, however, we consider the enormous quantity of seeds 
produced by plants; that great nnmbers of these are more or 
less adapted to be carried by the wind ; and that winds of great 
violence and long duration occur in most parts of the world, we 
are as sure that seeds must be carried to great distances as if 
we had seen them so carried. Sucli storms carry leaves, hay, 
dust, and many small objects to a great height in the air, while 
many insects have been conveyed by them for hundreds of 
miles out to sea and far beyond what their unaided powcra of 
flight could have effected. 

Jlirili as Affmts in tfie Dispersal of Plants. — Birds are un- 
doubtedly important agents in the dispersal of plants over wide 
spaces of ocean, cither by swallowing fruits and rejecting the 
seeds in a state tit for gcrintnntion, or by the seeds becoming at- 
tached lo the plumage of ground-nesting birds, or to the feet of 
aquatic birds embedded in small quantities of mud or eartli. 
lllustriitions of these variona modes of transport will be found 



CUAP. v.] DISPERSAL OF ANIMALS AND PLANTS. 77 

in Chapter XII. when discussing the origin of tlie flora of the 
Azores and Bermuda. 

Ocean Currents as Agents in Pluntrdispersal. — Ocean currents 
are undoubtedly more important agents in conveying seeds of 
plants than they are in the case of any other organisms, and a 
considerable body of facts and experiments liave been collected 
proving that seeds may sometimes be carried in this way many 
thousand miles and afterwards germinate. Mr. Darwin made a 
series of interesting experiments on this subject, some of which 
will be given in the chapter above referred to. 

Dispersal along Moxmtain-chains. — These various modes of 
transport are, as will be shown when discussing special cases, 
amply sufficient to account for the vegetation found on oceanic 
islands, which almost always bears a close relation to that of the 
nearest continent; but there are other phenomena presented by 
the dispersal of species and genera of plants over very wide 
areas, especially when they occur in widely separated portions of 
the Northern and Southern hemispheres, that are not easily ex- 
plained by such causes alone. It is here that transmission along 
mountain -chains has probably been eflfective; and the exact 
mode in which this has occurred is discussed in Chapter XXIII., 
where a considerable body of facts is given showing that exten- 
sive migrations may be effected by a succession of moderate 
steps, owing to the frequent exposure of fresh surfaces of soil 
or debris on mountain sides and summits, offering stations on 
which foreign plants can temporarily establish themselves. 

Antiquity of Plants as Affecting their Distribution. — ^We have 
already referred to the importance of great antiquity in ena- 
bling us to account for the wide dispersal of some genera and 
species of insects and land shells, and recent discoveries in fossil 
botany show that this cause has also had great influence in the 
case of plants. Eich floras have been discovered in the Miocene, 
the Eocene, and the Upper Cretaceous formation, and these con- 
sist almost wholly of living genera, and many of them of species 
very closely allied to existing forms. We have therefore every 
reason to believe that a large number of our plant species have 
surnved great geological, geographical, and climatal changes ; 
and this fact, combined with the varied and wonderful powers 



78 ISLAND LIFE. [Part L 

of dispersal many of tliem possess, render it far less diflScult to 
underetand the examples of wide distribution of the genera and 
species of plants than in the case of similar instances among an- 
imals. This subject will be further alluded to when discussing 
the origin of the New Zealand flora in Chapter XXII. 



Chap. VI.] GEOGRAPHICAL AND GEOLOGICAL CHANGES. 79 



CHAPTER VI. 

GEOGRAPHICAL AND GEOLOGICAL CHANGES: THE PERMANENCE 

OF CONTINENTS. 

Changes of Land and Sea, their Nature and Extent. — Shore-deposits and Stratified 
Rocks. — The Movements of Continents. — Supposed Oceanic Formations ; the 
Origin of Chalk. — Fresh-water and Shore Deposits as Proving the Permanence of 
Continents. — Oceanic Islands as Indications of the Permanence of Continents and 
Oceans. — General Stability of Continents with Constant Change of Form. — Effect 
of Continental Changes on the Distribution of Animals. — Changed Distribution 
Proved by the Extinct Animals of Different Epochs. — Summary of Evidence for 
the General Permanence of Continents and Oceans. 

The clhinges of land and sea wliicli have occurred in particu- 
lar cases will be described when we discuss the ori<ijin and rela- 
tions of the faunas of the different classes of islands. "We have 
here only to consider the general character and extent of such 
changes, and to correct some erroneous ideas which are prevalent 
on the subject. 

Changes of Land and Sea^ their Nature and Extent. — It is a 
very common belief that geological evidence proves a complete 
change of land and sea to have taken place over and over again. 
Every foot of dry land has undoubtedly, at one time or other, 
formed part of a sea-bottom ; and we can hardly exclude the sur- 
faces occupied by volcanic and fresh -water deposits, since in 
many cases, if not in all, these rest upon a substratum of marine 
formations. At first sight, therefore, it seems a necessary infer- 
ence that when the present continents were under water there 
must have been other continents situated where we now find 
the oceans, from which the sediments came to form the various 
deposits we now see. This view was held by so acute and 
learned a geologist as Sir Charles Lyell, who says, " Continents, 
therefore, although permanent for whole geological epochs, shift 
their positions entirely in the course of ages." * Mr. T. Mellard 

> "Principles of Geology," 1 lih ed., Vol. I., p. 258. 



80 



ISI^HD LIf H. 



[PA«rI. 



Reado, late President of the Geological Society of Livei'iiool, so 
recently as 1878, saj-e, " While believing that the ocean depths 
are of enormotiB age, it is impossible to resist other evidences 
that they have once been land. The very continuity of animal 
and vegetable life on the globe points to it. The molluscous 
fauna of the eastern coast of North America is very similar to 
that of Europe, and this could not liave happened without lit- 
toral continuity ; yet there are depths of 1500 fathoms between 
these continents.'" It is certainly strange that a geologist 
ehould not remember the recent and loug-continucd warm cli- 
mates of the arctic regions, and see that a connection of Noi'tli- 
ern Europe by Iceland witli Greenland and Ijibrador over a sea 
far less than a thousand fathoms deep would furnish the "lit- 
toral continuity" required. Again, in the same pamphlet Mr. 
Ileade says, " It can be uiathematically demonstrated that the 
whole, or nearly the whole, of the sea-bottom has been at one 
time or other dry land. If it were not so, and the oscillations 
of the level of the land with respect to the sea were con&ned 
within limits near the present continents, the results would have 
boon a gradual diminution instead of development of the calcare- 
ons rocks. To state the case in common language, tlie calcareous 
portion of the rocks would have been washed ont during the 
inntations, the destruction and re-deposit of the continental 
rocks, and eventually deposited in the depths of the immutable 
soa far from land. Immense beds of limestone would now exist 
ut the bottom of the ocean, while the land would be composed 
of sandstones and argillaceous shales. The evidence of chemis- 
try tlius confirms the inductions drawn from the distribution of 
animal life npon the globe." 

So far from this being a " mathematical demonstration," it ap- 
pears to me to 1)0 a complete misinterpretation of the facte. 
Animals did not create the limo which tliey secrete from the sea- 
water, and therefore wo have every reason to believe tiiut the 
inorganic sources which originally supplied it still keep np that 
supply, though perhaps in diminished quantity. Again, the 
great lime-secreters — corals — work in water of moderate deptli 



II Inilox of GeoloBicil Time." 



Chap. VI.] GEOGRAPHICAL AND GEOLOGICAL CHANGES. 81 

(that is, near land), while there is no proof whatever that there is 
any considerable accumulation of limestone at the bottom of the 
deep ocean. On the contrary, the fact ascertained by the Chal- 
lenger^ that beyond a certain depth the " calcareous " ooze ceases, 
and is replaced by red and gray clays, although the calcareous 
organisms still abound in the surface waters of the ocean, shows 
that the lime is dissolved again by the excess of carbonic acid 
usually found at great depths, and its accumulation thus pre- 
vented. As to the increase of limestones in recent as compared 
with older formations, it may be readily explained by two con- 
siderations : in the first place, the growth and development of 
the land in longer and more complex shore-lines, and the in- 
crease of sedimentary over volcanic formations, may have offered 
more stations favorable to the growth of coral, while the solubil- 
ity of limestone in rain-water renders the destruction of such 
rocks more rapid than that of sandstones and shales, and would 
thus lead to their comparative abundance in later as compared 
with earlier formations. 

However weak we may consider the above-quoted arguments 
against the permanence of oceans, the fact that these arguments 
are so confidently and authoritatively put forward renders it 
advisable to show how many and what weighty considerations 
can be adduced to justify the opposite belief, which is now rap- 
idly gaining ground among students of earth-history. 

Shore -deposits and Stratified Hocks. — If we go round the 
shores of any of our continents, we shall always find a consid- 
erable belt of shallow water, meaning thereby water from a 
hundred to a hundred and fifty fathoms deep. The distance 
from the coast-line at which such depths are reached is seldom 
less than twenty miles, and is very frequently more than a hun- 
dred, while in some cases such shallow seas extend several hun- 
dred miles from existing continents. The great depth of a 
thousand fathoms is often reached at thirty miles from shore, 
but more frequently at about sixty or a hundred miles. Bound 
the entire African coast, for example, this depth is reached at 
distances varying from forty to a hundred and fifty miles (ex- 
cept in the Ked Sea and the Strait of Mozambique), the aver- 
age being about eighty miles. 

G 



ISLAHD LITE. 



[Paw I. 



iS'ow the iinmerous Epeciiiieiis of sea-bottoms colleeted during 
the voyage of tliu Vkallenger eliow tliat Inie shoi-e-deposits — 
that is, materials deniiJcd from tlie lauil and carried down us 
sedimeut by rivors — aro uliaost always confined witliin a dis- 
tance of fifty or a hundred miles of the coast, the linest mud 
only being sometimes earried a hundred and iifty or, rarely, 
two hundred iiiilcs. As the sediment varies in coarseness and 
density, it is ovideut that it will sink to the bottom at iincqnal 
distances, the hulk of It sinking comparatively near shore, wliile 
only the very finest and (ilmost impalpable mud will he carried 
out to the farthest limits. lieyond these limits the only depos- 
its (with few exceptions) are organic, consisting of the sliells of 
minute calcareous or siliceous organisms with some decomposed 
pumice and volcanic dust which fiouCs out to mid-ocean. It 
follows, tliercforc, that by far the larger part of all etratiticd 
deposits, especially those which consist of sand or pebbles or any 
visible fragments of rock, must have been formed within fifty 
or a hundred miles of then existing continents; or if at a 
greatci' distance, in shallow inland seas receiving deposits from 
more sides than one, or in certain exceptional areas where deep 
ocean currents carry the dohris of land to greater distances,' 

If we now examine the stratified rocks found in the very 
centre of all our great continents, we find them to consist of 
sandstones, limestones, conglomerates, or shales, which must, 
aa wc havo seen, have been deposited witliin a comparatively 
short distance of a sea-ehoro. Professor Archibald (ieikie says, 
" Among the thickest masses of sedimentary rock — those of the 
ancient i'alasozoift systems — no features recur more continnally 
than the alternations of dltferent sediments, and the recurrence 
of BUpfacea covered with well-preserved ripplc-marks, trails and 



' In li>> "Preliminnry Report on Oceanic Deposit," Mr. Murrnvinyt, "Ichnibccn 
ronnd Ihiit llio deposits taking place nenr continent* nnd inlands have racaivcd Iheir 
chief charncteriKtio rrom the preaence of tlie debris of adjacent laiida. In aonie 
cnies these deposits eitlend to n dieliince of over a hundred and Rfry miles ttara 
ihB const."— /Vx-wrfisw <•/ lilt liosal &ei«/y. Vol, XXIV.. |J. CIO. 

"The maturiiili i>i suspension appear tu lie almttat entirely Jepoiilod wiihln tuo 
Uanind miles of the \im<l."—Proc€fdmg$ of lit HoyolSoculga/EiiMmryli, 1870-77, 
p. 2.i3. 




Chap. VI.] GEOGRAPHICAL AND GEOLOGICAL CHANGES. 83 

burrows of annelides, polygonal and irregular desiccation-marks, 
like the cracks at the bottom of a sun-dried muddy pool. These 
phenomena unequivocally point to shallow and even littoral 
waters. They occur from bottom to top of formations which 
reach a thickness of several thousand feet. They can be inter- 
preted only in one way — viz., that the formations in question be- 
gan to be laid down in shallow water; that during their forma- 
tion the area of deposit gradually subsided for thousands of 
feet ; yet that the rate of accumulation of sediment kept pace, 
on the whole, with this depression ; and hence that the original 
shallow-water character of the deposits remained, even after the 
original sea-bottom had been buried under a vast mass of sedi- 
mentary matter." He goes on to say that this general state- 
ment applies to the more recent as well as to the more ancient 
formations, and concludes, " In short, the more attentively the 
stratiKed rocks of the earth are studied, the more striking be- 
comes the absence of any formations among tliem which can 
legitimately be considered those of a deep sea. Tliey have all 
been deposited in comparatively shallow water." * 

The arrangement and succession of the stratified rocks also 
indicate the mode and place of their formation. We find them 
stretching across the country in one general direction, in belts 
of no great width, though often of immense length, just as we 
should expect in shore-deposits; and they often thin out and 
change from coarse to fine in a definite manner, indicating the 
position of the adjacent land from the debris of which they 
were originally formed. Again quoting Professor Geikie, "The 
materials carried down to the sea would arrange tliemselves 
then as they do still, the coarser portions nearest the shore, the 
finer silt and mud farthest from it. From the earliest geolog- 
ical times the great area of deposit has been, as it still is, the 
marginal belt of sea-floor skirting the land. It is there that nat- 
ure has always strewn the dust of continents to be." 

The Movements of Continents. — As we find these stratified 
rocks of different periods spread over almost the whole surface 
of existing continents where not occupied by igneous or meta- 

* ** Geogrnphicnl Evolution," Proceedings of the Royal (Jeographical Society ^ 1871), 
p. 426. 



84 



ISLAND LIFE. 



[Pak* I. 



morpliic rneks, it follows tliat nt one period or another each 
part of tho continent )ms been under tlic eeii, but nt the same 
time not far from the shore. Oeologista now recognize two 
kinds of movements by which the deposits bo formed have been 
elevated into dry land — in the one case the strata remain almost 
]evel and undisturbed, in the other they are contorted and crum- 
pled, often to an enormous extent. The former often prevails 
in plains and plateaus, while the latter ia almost always found 
in the great mountain-ranges. We are thus led to picture the 
land of the globe 113 a flexible area in a state of alow but inces- 
sant change; the changes consisting of low undulations wliich 
creep over the surface so aa to elevate and depress limited por- 
tions in succession witiiout perceptibly affecting their nearly 
horizontal posilion, and also of intense lateral compression, 
supposed to be produced by parlinl subsidence along certain 
lines of weakness in the earth's crust, tiie effect of which is to 
cnimple the strata and force up certain areas in great contorted 
masses, whiuh, wheu carved out liy siibaerial denudation into 
peaks and valleys, constitute oiir great mountain systems.' In 
this way every part of a continent may agaiu and again have 
snnk beneath the sea, and yet as a whole may never have ceased 
to exist as a continent or a vast continental archipelago. And 
as subsidence will always be accompanied by deposition, piles 
of marine strata many thousand feet tliick may have been 
formed in a sea which was never very deep, by means of a slow 
depression either continnous or intermittent, or through alter- 
nate subsidences and elevations, each of moderate amount. 
Supposed Oceanic Formationa; the Orifjuk of Chalk. — There 



' Pioreseor Dunn points oiil llinl llie regions nlik'li. nfler lung iinilvrgoiitg aabsiil- 
enre, nnJ ncciimuinling rust \it\e» of eedimenlnry deiioaiiR, liave hpen elevuled iutu 
■nuunltiin -ranges, liave tiierab; become itilT nnil unyieliliiig, nnd tbal the next de- 
(ireuion nnd Bubiec|uent agibeiivnl will lie Bitunteil on one ur [be olbor side of il; 
n[id he ahows ibitt in North Antnicn ibU is ibu cnw niih all llio mountnins of the 
tmnioNTi; geological funnntionB. Ilius, ileprcasiont anil clevBlions of extreme ilow- 
IW4, bill often of rnsl nmount, have oocunwl aiicceuirelj in realricled nt^cent arens ; 
nnd tlie effect bu been to bring each poition In auccewiion beneiiih tbe occnn, but nl- 
uays bonlereJ on one or Iwlh lidn \>j ilie temoindor of tbe continent, fmin tbe den- 
udnlion of wliicb the deinsita are formed which, on the siibacqaaiit npheaTol, bccoiM 
ii-rnNgcj (" MnnnnI of Geology," r J ed., p. 7r>!). 



Chap. VI.] GEOGKArHlCAL AND GEOLOGICAL CHANGES. 85 

seems very good reason to believe that few, if any, of the rocks 
known to geologists correspond exactly to the deposits now 
forming at the bottom of our great oceans. The white oceanic 
mud, or Globigerina ooze, found in all the great oceans at depths 
varying from 250 to nearly 3000 fathoms, and almost constant- 
ly in depths under 2000 fathoms, has, however, been supposed 
to be an exception, and to correspond exactly to our white and 
gray chalk. Hence some naturalists have maintained that there 
has probably been one continuous formation of chalk in the 
Atlantic from the Cretaceous epoch to the present day. This 
view has been adopted chiefly on account of the similarity of 
the minute organisms found to compose a considerable portion 
of both deposits, more especially the pelagic foraminifera, of 
which several species of Globigerina appear to be identical in 
the chalk and the modern Atlantic mud. Other extremely mi- 
nute organisms, whose nature is doubtful, called coccoliths and 
discoliths, are also found in both formations, while there is a 
considerable general resemblance between the higher forms of 
life. SirWyville Thomson tells us that "sponges are abundant 
in both, and the recent chalk-mud has yielded a largo number 
of examples of the group Porifera vitrea, which find their near- 
est representatives among the Ventriculites of the white chalk. 
The echinoderm fauna of the deeper parts of the.Atlantic basin 
is very characteristic, and yields an assemblage of forms which 
represent in a remarkable degree the corresponding group in 
the white chalk. Species of the genus Cidaris are numerous; 
some remarkable flexible forms of the Diademidae seem to ap- 
proach Echinothuria." * Now, as some explanation of the ori- 
gin of chalk had long been desired by geologists, it is not sur- 
prising that the amount of resemblance shown to exist between 
it and some kinds of oceanic mud should have been at once 
seized npon, and the conclusion arrived at that chalk is a deep- 
sea oceanic formation exactly analogous to that which has been 
shown to cover large areas of the Atlantic, Pacific, and South- 
ern oceans. 

But there are several objections to this view which seem fatal 

^Natttre, Vol IL, p. 297. 



86 ISLAND LIFE. [Part L 

to its acceptance. In the first place, no specimens of Globigerina 
ooze from the deep ocean-bed yet examined agree even approx- 
imately with clialk in chemical composition, only containing 
from 44 to 79 per cent, of carbonate of lime, with from 5 to 11 
per cent, of silica, and from 8 to 33 per cent, of alumina and 
oxide of iron.* Chalk, on the other hand, contains usually from 
94 to 99 per cent, of carbonate of lime, and a very minute quan- 
tity of alumina and silica. This large proportion of carbonate 
of lime implies some other source of this mineral, and it is prob- 
ably to be found in the excessively fine mud produced by the 
decomposition and denudation of coral reefs. Mr. Dana, the 
geologist of the United States Exploring Expedition, found in 
the elevated coral reef of Oahu, one of the Sandwich Islands, 
a deposit closely re^mbling chalk in color, texture, etc. ; while 
in several growing reefs a similar formation of modern chalk, 
undistinguishable from the ancient, was observed.* Sir Charles 



> Sir W. Thomson, ** Voyage of the Challenger,*' Vd. IL, p. 374. 
' The following is the analysis of the chnlk at Oahu : 

Carbonate of lime 92.800 per cent. 

Carbonate of magnesia 2.385 *' 

Alumina 0.250 ** 

Oxide of iron 0.543 ** 

Silica 0.750 " 

rhosphoric nciU and fluorine 2.113 ** 

Water and loss 1.148 ** 

This chalk consists simply of comminuted corals and shells of the reef. It has 
been examined microscopically and found to bo destitute of the minute organisms 
abounding in the chnlk of England (** Geology of the United States Exploring Ex- 
pedition," p. 150). 

This absence of Globigerinoc is a local phenomenon. They arc quite absent in the 
Arafiira Se^i, and no Globigerina ooze was fuund in any of the enclosed sens of the 
Pacific; but with these exceptions the Globigerina; **are really found all over the 
bottom of the ocean ** (Murray on "Oceanic Deposits," Proceedings of the Royal So- 
ciety, Vol. XXIV., p. 523). 

The above analysis shows a far closer resemblance to chalk th.an that of the Glo- 
bigerina ooze of the Atlantic, four specimens of which, given by Sir W. Thomson 
("Voyage of the Cliallenger," Vol. II., Appendix, pp. 374-376, Nos. 9, 10, 11, and 
12), from the mid-Atlantic, show the following ])roi)ortions : 

Carbonate of lime 43.93 to 70.17 per cent. 

Carbonate of magnesia 1.40 to 2.58 ** 

Alnmina and oxide of iron 0.00? to 32.98 ** 

Silica 4.G0 to 11.23 ** 



Chap. VI.] GEOGRAnilCAL AND GEOLOGICAL CHANGES. 87 

Lyell well remarks that the pure calcareous mud produced by 
the decomposition of the shelly coverings of mollusca and zoo- 
phytes would be much lighter than argillaceous or arenaceous 
mud, and being thus transported to greater distances would be 
completely separated from all impurities. 

Now the GlobigerinoB have been shown by the CJiaUenger 
explorations to abound in all moderately warm seas ; living both 
at the surface, at various depths in the water, and at the bot- 
tom. It was long thought that they were surface-dwellers only, 
and that their dead tests sank to the bottom, producing the Glo- 
big6rina ooze in those areas where other deposits were absent or 
scanty. But the examination of the whole of the dredgings and 
surface-gatherings of the Challenger by Mr. H. B. Brady has led 
him to a different conclusion ; for he finds numerous forms at the 
bottom quite distinct from those which inhabit the surface, while, 
when the same species live both at surface and bottom, the lat- 
ter are always larger and have thicker and stronger cell-walls. 
This view is also supported by the fact that in many stations 
not far from our own shores Globigerinje are abundant in bot- 
tom dredgings, but arc never found on the surface in the tow- 



In addition to tho above, there is n qitnntity of insoluble residue consisting of sronll 
particles of sanidinc, nugite, hornblende, and magnetite, supposed to be the product 
of rolcanic dust or ashes carried either in the air or by ocean currents. This volcanic 
matter amounts to from 4. GO to 8.33 per cent, of the Globigerina ooze of the mid- 
Atlantic, where it seems to be always present; and the small proportion of similar 
matter in true chalk is another proof that its origin is difTerenr, and that it was de- 
posited far more rapidly than the oceanic ooze. 

The following analysis of chalk by Mr. D. Forbes will show the difference between 
the two formations : 

Gray Chnlk. White Chalk. 
Folkestone, Shoreham, 

Carbonate of lime 94.09 98.40 

Carbonate of mngnesia 0.31 0.08 

Alumina and phosphoric acid a trace 0.42 

('hloiide of sodium 1.29 

Insoluble debris 3. 6 1 1.10 

(From Quarterly Journal of the Geological Society^ Vol. XX VII.) 

Tiie large proportion of carbonate of lime, and t)ie very small quantity of silica, 

alumina, and in.soliible debris, at once distinguish true chalk from the Globigerina 

ooze of tlic deep ocean- bed. 



ISI.AND LIFE. 



[PjhiL 



iiig-nets.' Tliese orgftnisiiis tiien exist almost universally where 
the waters are pure and are not too cold, and they would Jiatii- 
riiDy abound inoeC where the difiasion of carbonate of lime both 
ill Buspeiision and eolation afforded them an abundant Bupply 
of material for their shelly coverings. Dr. Wallich believes that 
they flourish best where the warm watera of the Gulf Sti-eaiu 
bring organic matter from which they derive nutriment, since 
they are wholly wanting in the eonrso of the arctic current be- 
tween Greenland and Labrador. Ur. Carpenter also assures us 
that thoy are rigorously liuiitcd to warm areas. 

Now, with regard to the depth at which oiip chalk was formed, 
we Lave evidence of sevei-al distinct kinds to show that it was 
not pi-ofoiindly oceanic. Mr. J. Murray, in the Report already 
referred to, says, " The Globigerina oozes which we get in shal- 
low water resemble tlic chalk mnch more than tliose in deeper 
water, say over 1000 fathoms."' This is important and weighty 
evidence, and it is supported in a striking manner by the nature 
of the moiluEcnn fauna of the chalk. Mr. Gwyn Jeffries, one 
of our greatest authorities on shells, who has himself dredged 
largely both in deep and shallow water, and who has no theory 
to support, has carefully examined tliis question. Taking the 
whole scries of genera which arc found in the Chalk formation, 
seventy-one in uuuibcr, he declares that they are all compara- 
tively shallow-water forms, many living at depths not exceeding 
forty to fifty fathoms, while some are confined to etiU shallower 
waters. Even more important is the fact that the genera espe- 
cially characteristic of the deep Atlantic ooze — Leda, Verticor- 
din, Nelera, and the Bulla fnmily^are either very rare or en- 
tirely wanting in the ancient Cretaceous deposits,' 

Let us now see how the various facts already adduced will 
enable us to esplaiu the peculiar characteristics of the Chalk 
formation. Sir Charles Lyelt tells ns that "pure Chalk, of 
nearly uniform aspect and composition, is met with in a north- 



' "Koios on Reliculnrinn ltliUopo(ln,"iii Microtcopicai JoMmul, Vul, XIX., N 
feriflii, p. 81. 
' Proendinti of the Royi-t SecUlf, Vol. XVI V., p. 532- 
* Sea I'lvtiiteniiiil AdJieis in Sect. D of liiilisli Associiuion ni I'lj-mouili, 1877 



CUAP.VI.] GEOGUAPHICAL AND GEOLOGICAL CHANGES. 89 

west and southeast direction, from the north of Ireland to the 
Crimea, a distance of about 1140 geographical miles; and in an 
opposite direction it extends from the south of Sweden to the 
south of Bordeaux, a distance of about 840 geographical miles." 
This marks the extreme limits within which true chalk is found, 
though it is by no means continuous. It probably implies, how- 
ever, the existence across Central Europe of a sea somewhat 
larger than the Mediterranean. It may have been much larger, 
because this pure chalk formation would only be formed at a 
considerable distance from land, or in areas where there was no 
other shore - deposit. This sea was probably bounded on the 
north by the old Scandinavian highlands, extending to Northern 
Germany and Northwestern liussia, where Palaeozoic and an- 
cient Secondary rocks have a wide extension, though now par- 
tially concealed by late Tertiary deposits ; while on the south it 
appears to have been limited by land extending through Aus- 
tria, South Germany, and the South of France, as shown in the 
map of Central Europe during the Cretaceous period in Profess- 
or lleer's "Primeval World of Switzerland," p. 175. To the 
north the sea may have had an outlet to the Arctic Ocean be- 
tween the Ural range and Finland. South of the Alps there 
was probably another sea, which may have communicated with 
the northern one just described, and there was also a narrow 
strait across Switzerland, north of the Alps, but, as might be ex- 
pected, in this only marls, clays, sandstones, and limestones were 
deposited instead of true chalk. It is also a suggestive fact that 
both above and below the true chalk, in almost all the countries 
where it occurs, are extensive deposits of marls, clays', and even 
pure sands and sandstones, characterized by the same general 
types of fossil remains as the chalk itself. These beds imply 
the vicinity of land, and this is even more clearly proved by 
the occurrence, both in the Upper and Lower Cretaceous, of de- 
posits containing the remains of land plants in abundance, indi- 
cating a rich and varied flora. 

Now all these facts are totally opposed to the idea of any- 
thing like oceanic conditions having prevailed in Europe during 
the Cretaceous period ; but it is quite consistent with the exist- 
ence of a great Mediterranean sea of considerable depth in its 



90 



ISLAND LIFE. 



tPAl 



central portions, and ocoiipj'ing, either at one or successive peri- 
ods, tlio whole urea of tlie Cretaceous formation. We may also 
note that the Maestriclit beds in Belgium and the Faxiie chalk 
in Denmnrk are both highly coralline, the latter being, in fact, 
as completely composed of corals as a modern conil reef; so that 
we have hero a clear indication of the sonrce w-lience the white 
ciilcareoua mud was derived which forms the basis of chalk. If 
we suppose that during this period the comparatively shallow 
eedrbottom between Scandinavia and Greenland was elevated, 
forming a land connection between these countries, the result 
wonld be that a large portion of the Gulf Stream would be di- 
verted into the inland European sea, and would bring with it 
that abundance of Globigerinte and other foraininifera which 
form such an important constituent of chalk. This sea was 
probably bordered with islands and coral reefs; and if no very 
large rivers flowed into it, we should have all the conditions for 
the production of the true chalk, as well as tlio other niemlrcrs 
of the Cretaceous formation. The products of the denudation 
of its shores and islands would form the %'arious sandstones, 
marls, and clays which would be deposited almost wholly within 
a few miles of its coasts; while the great central sea, perhaps at 
no time more than a few thousand feet deep, would receive only 
the impalpable mud of tl^e coral reefs and the constantly falling 
tests of foraminifera. Tliese wonld embed and preserve for bs 
the numerous cchinoderms, sponges, and niollusca which lived 
upon the bottom, tho fishes and turtles which swnm in its 
waters, and sometimes the winged reptiles that flew overhead. 
Tiio abundance of ammonites and other ccphalopods in the 
Chalk is another indication that the water in which they live<l 
was not very deep, since Dr. S. P. Woodward ttiinks that these 
organisms were limited to a depth of about thirty fathoms. 

Tho best example of the modern formation of chalk is per- 
hape to be found on the coasts of subtropical North America, 
as described in the following passage: 

"The observations of Ponrtales show that the steep banks of 
Bahama are covered with soft white llme-umd. The limo-bot- 
tom, which consists almost entirely of Polytlmlamia, covers in 
greater depths the entire channel of Florida. This formation 



Chap. VI.] GEOGRAPHICAL AND GEOLOGICAL CHANGES. 91 

extends without interruption over the whole bed of the Gulf 
Stream in the Gulf of Mexico, and is continued along the At- 
lantic coast of America. The commonest genera met with in 
this deposit are Globigerina, Eotalia cultrata, in large numbei's, 
several Textilariee, Marginuliuse, etc. Besides these, small free 
corals, Alcj'onidae, Ophiuiw, MoUusca, Crustacea, small fishes, 
etc., are found living in these depths. The whole sea-bottom 
appears to be covered with a vast deposit of white chalk still in 
formation." * 

There is yet another consideration which seems to have been 
altogether overlooked by those who suppose that a deep and 
open island-studded ocean occupied the place of Europe in Cre- 
taceous times. No fact is more certain than the considerable 
break, indicative of a great lapse of time, intervening between 
the Cretaceous and Tertiary formations. A few deposits of in- 
termediate age have indeed been found, but these have been 
generally allocated either with the Chalk or the Eocene, leaving 
the gap almost as pronounced as before. Now, what does this 
gap mean ? It implies that when the deposition of the various 
Cretaceous beds of Europe came to an end, they were raised 
above the sea-level and subject to extensive denudation, and 
that for a long but unknown period no extensive portion of 
what is now European land was below the sea-level. It was 
only when this period terminated that large areas in several 
parts of Europe became submerged and received the earliest 
Tertiary deposits known as Eocene. If, therefore, Europe at 
the close of the Cretaceous period was generally identical with 
what it is now, and perhaps even more extensive, it is absurd to 
suppose that it was all, or nearly all, under water during that 
period ; or, in fact, that any part of it was submerged except 
those areas on which we actually find Cretaceous deposits, or 
where we have good reason to believe they have existed. 

The several considerations now adduced are, I think, suflBcient 
to show that the view put forth by some naturalists (and which 
has met with a somewhat hasty acceptance by geologists) that 
our white chalk is an oceanic formation strictly comparable 

> Geological Magazine, 1871, p. 42G. 



92 



ISLAND LIFE. 



[T*n* I. 



wUli tliHt now foniiing at <Ioptlts of a thousand fatlioiiis and ii|j- 
waivis ill llic centre o£ tlie Atlantic, gives a totally eiToneous 
idea of the actual condition of Europe during tliat period. In- 
stead of lieing a wide ocean, ivitli a few scattered islands, corn- 
parable to some parts of t!ie Pacific, it formed as truly a portion 
of the great nortliern continent as it does now, although the in- 
land seas of that epoch may have heen more extensive and more 
numerous than they are at the pi-esent day." 

J^resh^oater and Shore Di'ponits as Proving iite Pcmumciice 
of Continctite. — The view here maintained, that all known ma- 
rine deposits have been formed near the coasts of continents and 
islantla, and that our actual continents have been in continuons 
existence under variously modified forms during the whole 
period of known geological history, is further supported by an- 
other and totally distinct series of facts. In almost every period 
of geology, and in all the continents which have been well ex- 
amined, there are found lacustrine, estuarine, or shoro deposits, 
containing the remains of land animals or plants, thus demon- 
etrating the continuous existence of extensive land areas on or 
adjoining the sites of our present continents. Beginning with 
the Miocene, or Middle Tertiary, period, we have such deposits 
with remains of land animals or plants in Devonshire and Soot- 
land, in France, Switzerland, Germany, Croatia, Vienna, Greece. 
North India, Central India, Burinah, North America (both cast 
and west of the Kocky Mountiiins), Greenland, and other parts 
of the arctic regions. In the older Eocene period similar for- 

' [ii liblecinre on " fiooginpliicnl Evolii(ion"(whithwnapi[llishednfic!rlhogteiiicr 
pni'l of iliU clinpior hnJ b«eii nriileii), I'mfcaaor Goikie ex|iress«« rient in coropleie 
nccordnnco with tliosB liere ndiiwiileJ. He »»]■», "Tbo nexi long era, tlie (Jrein- 
cooio, tvot morn reninrkable luralow ■ccumiil.ition of rock tinJci tlio am ttinn for the 
fornitlinn of neiv Iniid. During Ilmt time the AlUntic ieiil its naicrs ni^roM iho 
whole of tCuropa nnd into Abiii. But lliey ncre probubl}' nunhcra more tliuti n fen* 
hunilrcJ fcol doop orar ih« sito of oiir coiiliiient, even at llieir dwpwt pun. L'lion 
ilieir bollotn ihore gntliered n \mi mass of cnkareoua niud, compoEcd in grenl pni'l 
orforaniinifeni, corals, «chiiiodern», nr>J moUiisks. Uur Kngliuli chnlki vrliivb ranges 
ncrosa ilia Monb of Krnni^a, IlelKinm. Denninrk, and Ihe Norlli of Gernuiny, reprc- 
wnu n poriiuii of tli« dspodu of ihnt un-Hoor." Tlio weigtir}' aiidiorit;' of iIis Di- 
rector of llie (ieological Surrey of Sculluiid mny p«rlinpi cutiM lamc geologitis la 
tnoiliry tbeir \ii?w« as la tha d«cp.«ea origin of clialk, wlio would liure ireaied any 
iitguincnls nclrnnccd by myself n* not woriliy of coniiJcmlion. 




Chap. VI.] GEOGRAPHICAL AND GEOLOGICAL CHANGES. 93 

mations are widely spread in the South of England, in France, 
and to an enormous extent on the central plateau of North 
America ; while in the Eastern States, from Maryland to Ala- 
bama, there are extensive marine deposits of the same age, 
which, from the abundance of fossil remains of a large cetacean 
(Zeuglodon), must have been formed in shallow gulfs or estua- 
ries where these huge animals were stranded. Going back to 
the Cretaceous formation, we have the same indications of per- 
sisting lands in the rich plant-beds of Aix-la-Chapelle and a few 
other localities on the Continent, as well as in coniferous fruits 
from the Gault of Folkestone ; while in North America Creta- 
ceous plant -beds occur in New Jersey, Alabama, Kansas, the 
sources of the Missouri, the Kocky Mountains from New Mex- 
ico to the Arctic Ocean, Alaska, British Columbia, California, 
and in Greenland and Spitzbergen ; while birds and land rep- 
tiles are found in the Cretaceous deposits of Colorado and other 
Western districts. Fresh -water deposits of this age are also 
found on the coast of Brazil. In the lower part of this forma- 
tion we have the fresh-water Wealden deposits of England, ex- 
tending into France, Hanover, and Westphalia. In the older 
Oolite or Jurassic formation we have abundant proofs of con- 
tinental conditions in the fresh-water and " dirt "-beds of the 
Purbccks, in the south of England, with plants, insects, and 
mammals ; the Bavarian lithographic stone, with fossil birds 
and insects; the earlier "forest marble" of Wiltshire, with rip- 
ple-marks, wood, and broken shells, indicative of an extensive 
beach ; the Stonesfield slate, with plants, insects, and marsupials ; 
and the Oolitic coal of Yorkshire and Sutherlandshire. Beds 
of the same age occur in the Kocky Mountains of North Amer- 
ica, containing abundance of Dinosaurians and other reptiles, 
among which is the Atlantosaurus, the largest land-animal ever 
known to have existed. Professor O. C. Mai-sh describes it as 
having been between fifty and sixty feet long, and when stand- 
ing erect at least thirty feet high ! * Such monsters could hardly 
have been developed except in an extensive land area. A- small 



' " Introduction nnd Succession of Vertebrate Life in Americn/'by Professor O. C. 
Marsh. Reprinted from the Popular Science Monthly^ March, April, 1S78. 



94 



ISLAND LIFE. 



[Part I. 



mammal, Dryolestes, liaa been diBOOvered in the eauie deposits, 
A rieli Jurassic flora has also beou found io East Siberia and 
the Amoor valley. Tlie older Triassic deposits nre very exlen- 
eively developed in Auierlca, and both in the Connecticut val- 
ley and the lloeky Mountains show tracks or remains of land 
reptiles, Hill phibians, and mammalia; white coal-fields of the same 
age in Virginia and Carolina produce abundance of plants. 
Here, too, is found the ancient mammal Microlestes, of Wiir- 
temberg, with the ferns, conifers, and Labyrinthodonts of the 
Bmiter Sandstone in Germany; while the beds of rock-salt in 
this formation, both in England and in many parts of the Con- 
tinent, could only have been formed in hiland seas or lakes, and 
thns etjually demonstrate continental conditions. 

We now pass into the oldest or Palieozoic fonnations, but 
Jind no diminution in the proofs of continental conditions. The 
Permian formation has a rich flora often producing coal in Eng- 
land, France, Saxony, Tliuringia, Silesia, and Eastern Ilusein. 
Coal-fields of the same ago occur iii Ohio, in North America. In 
tlie still more ancient Carboniferous formation we find the most 
remarkable proofs of the existence of our present continents at 
that remote epoch, in the wonderfid extension of coal-beds in 
all the known continents. Wo find them in Ireland, England, 
and Scotland; in France, Spain, Belgium, Saxony, Prussia, Bo- 
hemia, Hungary, Sweden, Spitzbergen, Siberia, liussia, Greece, 
Turkey, and Persia; in many parts of continental India; cxten- 
eivoly in China ; and in Australia, Tasmania, and New Zealand. 
In North America there are immense coal-fields in Nova Scotia 
and Now Brunswick, from Pennsylvania southward to Alabama, 
in Indiana and Illinois, and in Missouri ; .ind there is also a true 
coal formation in South Brazil. This wonderfully wide distri- 
bution of coal, implying a^ it does a rich vegetation and exten- 
sive land areas, carries hack the proof of the persistence and 
general identity of our continents to a period so remote that 
none of the higher animal types had probably Iteen developed. 
But we can go eveu further hack than this, to the preceding 
Devonian formation, which was almost certainly an inland de- 
posit often containing remains of fresh-water shells, plants, and 
even insects; while Professor Ramsay believes tliat he has 



Chap. VI.] GEOGRAPHICAL AND GEOLOGICAL CHANGES. 95 

found " sun-cracks and rain-pittings " in the Longmynd beds of 
the still earlier Cambrian formation.' If now, in addition to 
the body of evidence here adduced, we take into consideration 
the fresh-water deposits that still remain to be discovered, and 
those extensive areas where they have been destroyed by denu- 
dation, or remain deeply covered up by later marine or volcanic 
formations, we cannot but be struck by the abounding proofs of 
the permanence of the great features of land and sea as they 
now exist ; and we shall see how utterly gratuitous, and how 
entirely opposed to all the evidence at our command, are the 
hypothetical continents bridging over the deep oceans, by the 
help of which it is so often attempted to cut the Gordian knot 
presented by some anomalous fact in geographical distribution. 
Oceanic Islands as Indications of the Permanence of Conti- 
nents and Oceans, — Coming to the question from the other side, 
Mr. Darwin has adduced an argument of considerable weight in 
favor of the permanence of the great oceans. He says (" Origin 
of Species,'* 6th ed., p. 288), " Looking to existing oceans, which 
are thrice as extensive as the land, we see them studded with 
many islands ; but hardly one truly oceanic island (with the ex- 
ception of New Zealand, if this can be called a truly oceanic 
island) is as yet known to afford even a fragment of any Palse- 
ozoic or Secondary formation. Hence we may perhai>8 infer 
that during the Palaeozoic and Secondary periods neither conti- 
nents nor continental islands existed where our oceans now ex- 
tend ; for had they existed. Palaeozoic and Secondary formations 
would in all probability have been accumulated from sediment 
derived from their wear and tear; and these would have been 
at least partially upheaved by the oscillations of level which 
must have intervened during these enormously long periods. If, 
then, we may infer anything from these facts, we may infer that 
where our oceans now extend, oceans have extended from the 
remotest period of which we have any record ; and, on the other 
hand, that where continents now exist large tracts of land have 
existed, subjected, no doubt, to great oscillations of level, since 
the Cambrian period." This argument standing by itself has 



1 (( 



Plnsicnl Geography nnd Geology of Great Bntnin,"5th ctl., p. 61. 



96 ISLAND LIFK. [Pant I. 

not rec-eivef! tlie attention it deserves, liut coming in snpport of 
the long scries of facta of an altogether distinct nature, going to 
show tlie permanence of continents, the cnimilativc effect of the 
whole must, I think, bo admitted to be irresistible." 

General Stability of Continents ■with Constant Change of Form. 
— It will be observed that the very same evidence which has 
been adduced to prove the general stability and permanence of 
onr continental areas aleo goes to prove that they liave been 
subjected to wonderful and repeated changes in detail. Every 
square mile of their surface has been again ami again under 
water, sonietimcs a few linndrt;d feet deep, sonietimea perhaps 
several thousands. Lakes and inland seas have been formed, 
Lave been filled up with sediment, and been subsequently raised 
into hills or even mountains. Aniisi of the sea have existed 
crossing the continents in various directioue, and thus completely 
isolating the divided portions for varying intervala. Seas liave 
been changed into deserts, nnd deserts into seas. Volcanoes 
have grown into mountains, have been degraded and sunk be- 
neath the ocean, have been covered with sedimentary deposits, 

' Of liiia it Una been iho cuaiom to qnnlfl llie lo-cBlled " riilgo " Joivn ilie conlie 
of the Ailnniic at indiFniing an cxieiisivc niicipnt liin J. ICren I'rofoMor Jiidd mlopi* 
llito view. Tar he aprnka tX iho gieitt bell of Tertinry rulcunocB "uiiicli extended 
iliroiigli Greenlnnd. Iceltind. ihe Fiiroe lolnnds, llie Ilcbridei, Irelnnd. Coniml Prance, 
■he Ilnrinn IVninsuU, tlic Aiarc«, Mndoii'o, Cnnnrieii, Cii]ie de Verd I*Iiind», At- 
ceiiaioii, St. Helena, and Trison d'Acunlia, and wliit'h conaliluted. pa slionn br llie 
rei^nt sounding* of H. M. S. CktdUtigtr, a mnunlpin-i-nnee compamble in iia exient, 
elevation, anj volranic cluirncier niili the Andes of Sonlh Amcricn" (Get/)ogiatl 
Mag., I8T(, p. 71). On exntnininK the diagram of the Atlantic Ocean i(i the 
CkallfKi/tr Beporla, No. T. n cnnsidernble part of ihii ridge ia found to he mora 
then IIHK) fnihoma (1ee]i, wliile ilio )ioriion cidleJ the " Connecting Kidge" eecniR to 
be dne in gmrt to the detHMita cnrried oul by Ilia river Amnton. In the nci^ibor- 
hood of the Atorea, Bl. Fanl'e Bucks, Aiccnslon, and Tiitlan d'Acnnha nre coniid- 
erable arcim viirviiig fiom 1200 lo IliOO fnthoma deep, wliile the reit of ttie ridge ia 
niually 1800 or HKM) riitlionia. The ahollower wnter ia no doubt due lo Tolennic m|<- 
heAval and the accnniulnlicin of volcanic ejoeiion*, nnd there may be many other 
dec]ily tDbmHrEeil old volcanoen on the ridges but ihnt it ever formed a i:hnin of 
fnonnlsini "rompamble in clevniion with the Andei" there eeema not n particle of 
evidence tu prcivc. It i*. hon-ever, probable that iliia riJge indicates Iho former ex- 
inlence of looie ronaidcrnblo Altanlic iiluD da, wliicli will aerve lo explain Iho preaence 
uf afew ideiilicnl gencrn. nnd even H[>ccies. of plnnta andiitaecM in ATricnnnd South 
Amerira. while the main body of the buna nnd flora of Iheae Ino contiaenti re- 
muiiia nidlcn.ly dialiocL 



Chap. VI.] GEOGRAPHICAL AND GEOLOGICAL CHANGES. 97 

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

Effect of Continental Changes on the Distribution of Animals, 
— It is impossible to exaggerate, or even adequately to conceive, 
the effect of these endless mutations on the animal world. 
Slowly but surely the whole population of living things must 
have been driven backward and forward from east to west, or 
from north to south, from one side of a continent or a hemi- 
sphere to the other. Owing to the remarkable continuity of all 
the land masses, animals and plants must have often been com- 
pelled to migrate into other continents, where in the struggle 
for existence under new conditions many would succumb ; while 
such as were able to survive would constitute those wide-spread 
groups whose distribution often puzzles us. Owing to the re- 
peated isolation of portions of continents for long periods, spe- 
cial forms of life would have time to be developed, which, when 
again brought into competition with the fauna from which they 
had been separated, would cause fresh struggles of ever-increas- 
ing complexity, and thus lead to the development and preser- 
vation of every weapon, every habit, and every instinct, which 
could in any way conduce to the safety and preservation of the 
several species. 

Changed Distribution Proved by the Extinct Animals of Dif- 
ferent Epochs, — We thus find that while the inorganic world has 
been in a state of continual though very gradual change, the 
species of the organic world have also, been slowly changing in 
fonn and in the localities they inhabit ; and the records of these 
changes and these migrations are everywhere to be found, in 
the actual distribution of the species no less than in the fossil 
remains which are preserved in the rocks. Everywhere the 
animals which have most recently become extinct resemble 

7 



ISL&NU LIVE. 



[fABT I. 



more or less closelj' those which now live in the Bame coniitrj ; 
and where there are esceptions to the rule we can generally 
trace theui to somo ciianjjed conditioos which have led to the 
extinction of certain tjpes. Eut when we go a little further 
bpj;k, to tho late or middle Tertiary deposits, we almost always 
find, along with forms which might have been the ancestors of 
soma now living, others which are now found only in remote 
regions, and often in distinct continents— clear indications of 
those extensive migrations wliich have ever been going on. 
Every large ialand eontaine in ita animal inhabitants a recot'd of 
the period when it was hist separated from the adjacent conti- 
nent; while some portions of existing continents still show by 
the comparative poverty and specialty of their animals that at 
no distant epoch they wore cnt off by arms of the sea, and formed 
islands. If the geological record were more perfect, or even if 
wo had as good a knowledge of that record in all parts of tho 
world as we have in Europe and North America, we conld arrive 
at much more accui-ate results than we are able to do with our 
present very imperfect knowledge of extinct forms of life ; but 
even with our present scanty information we are able to throw 
much light upon the past history of our globe and its inhabi- 
tants, and can sketch out with confidence many of the changes 
they must have undergone. 

^ummart/ of Evithnee for the General Permanence of Conti- 
nent and Oceans, — As this question of the permanence of our 
continents lies at tho root of all our inquiries into tho past 
citangee of the earth and its inhabitants, and as it is at present 
completely ignored by many writers, and even by naturalists of 
eminence, it will be well to summarize the various kinds of evi- 
dence which go to establish it.' We know as a fact that all scdi- 



' InarevicivofMr. Ren»lo'»"Clieiniail Deiiujniion anJ Gmlaglcnl TiniP,"iii .Vof- 
urt (Octoher 3, IM70>, the \vril«r rem&cki ns folluwt: "One of llie ruiiii}' notion* 
of suins DcieiitiRc itiinkeri meat* with no favor from Mr. Ilenile, ivhoM ^cclogiciil 
knowledge is ptaclicnl ii« well n* ilieoreiicnl. Tliey coniiJar [Iml becniiae the older 
rocki contain notbing like tlie present nnl clnyi, etc., of ilis ocenn-floor, tlie ocona 
Imva always been in itieir present poaitionn. Mr. RciiiIb poinii oat iliet the flmi 
jiroposilion ■■ not yet iiravnil ; nnd tlie Uintri lint ion of nnimnU nml pinnu, nnil the 
fiict tlinl the hulk of the simtn On luiiJ me or nmiiiie origin, iirc upjiused ii> the liy- 



Chap. VI.] GEOGRAPHICAL AND GEOLOGICAL CHANGES. 99 

mentary deposits have been formed under water, but we also 
know that they were largely formed in lakes or inland seas, or 
near the coasts of continents or great islands, and that deposits 
uniform in character and more than a hundred and fifty or 
two hundred miles wide were rarely, if ever, formed at the same 
time. The farther we go from the land, the less rapidly depo- 
sition takes place ; hence the great bulk of all the strata must 
have been formed near land. Some deposits are, it is true, con- 
tinually forming in the midst of the great oceans; but these are 
chiefly organic, and increase very slowly, and there is no proof 
that any part of the series of known geological formations ex- 
actly resembles them. Chalk, which is still believed to be such 
a deposit by many naturalists, has been shown, by its contained 
fossils, to be a comparatively shallow-water formation — that is, 
one formed at a depth measured by hundreds rather than by 
thousands of fathoms. The nature of the formations composing 
all our continents also proves the continuity of those continents. 
Everywhere we find clearly marked shore and estuarine depos- 
its, showing that every part of the existing land has in turn been 
on the sea-shore ; and we also find, in all periods, lacustrine for- 
mations of considerable extent with remains of plants and land 
animals, proving the existence of continents or extensive lands 
in which such lakes or estuaries could be formed. These lacus- 
trine deposits can be traced back through every period, from the 
newer Tertiary to the Devonian and Cambrian, and in every 
continent which has been geologically explored ; and thus com- 
plete the proof that our continents have been in existence under 
ever-changing forms throughout the whole of that enormous 
lapse of time. 

pothcsis." We must leave it to our reatlers to decide whether the "notion" devel- 
oped in this chapter is ** funny," or whether such hnsty and superficinl arguments as 
thoso here quoted from a "practical geologist" have any value as against the differ- 
ent classes of facts, all pointing to an opposite conclusion, which have now been briefly 
laid before them, supported as they are by the expressed opinion of so weighty an 
authority as Professor Archibald Geikie, who, in the lecture already quoted, says, 
" From all this evidence, we may legitimately conclude that the present land of the 
globe, though formed in great measure of maiine formations, has never lain under 
the deep sea ; but that its site must always have been near land. Even its thick 
marine limestones are the deposits of comparniively shallow water." 



100 ISLAND LIFE. [Pabt I. 

On the side of the oceans we have also a great weight of evi- 
dence in favor of their permanence and stability. In addition 
to their enormous depths and great extent, and the circumstance 
that the deposits now forming in them are distinct from any- 
thing found upon the land surface, we have the extraordinary 
fact that the countless islands scattered over their whole area 
(with one or two exceptions only) never contain any Palseozoic 
or Secondary rocks — that is, have not preserved any fragments 
of the supposed ancient continents, nor of the deposits which 
must have resulted from their denudation during the whole pe- 
riod of their existence 1 The exceptions are New Zealand and 
the Seychelles Islands, both situated near to continents, leaving 
almost the whole of the vast areas of the Atlantic, Pacific, Indian, 
and Southern oceans without a solitary relic of the great islands 
or continents supposed to have sunk beneath their waves. 



Chap. VIL] THE GLACIAL EPOCH. 101 






CHAPTER VII. 

CHANGES OF CLIMATE WHICH HAVE INFLUENCED THE DIS- 
PERSAL OF ORGANISMS: THE GLACIAL EPOCH. 

Proofs of the Recent Occurrence of a Glacial Epoch. — Moraines. — Travelled Blocks. 
— Glacial Deposits of Scotland: the "Till." — Inferences from the Glacial Phe- 
nomena of Scotland. — Glacial Phenomena of North America. — Effects of the Gla- 
cial Epoch on Animal Life. — Warm and Cold Periods. — Palasontological Evidence 
of Alternate Cold and Warm Periods. — Evidence of Interglacial Warm Periods 
on the Continent and in North America. — Migrations and Extinctions of Organ- 
isms Caused by the Glacial Epoch. 

We liavo now to consider another set of physical revolutions 
which have profoundly aflEected the whole organic world. Be- 
sides the wonderful geological changes to which, as we have seen, 
all continents have been exposed, and which must, with extreme 
slowness, have brought about the greater features of the dispersal 
of animals and plants throughout the world, there have been also a 
long succession of climatal changes, which, though very slow and 
gradual when measured by centuries, may have sometimes been 
rapid as compared with the slow march of geological mutations. 

These climatal changes may be divided into two classes, which 
have been thought to be the opposite phases of the same great 
phenomenon — cold or even glacial epochs in the temperate zones, 
on the one hand ; and mild or even warm periods extending into 
the arctic regions, on the other. The evidence for both these 
changes having occurred is conclusive; and as they must be 
taken account of whenever we endeavor to explain the past mi- 
grations and actual distribution of the animal world, a brief out- 
line of the more important facts and of the conclusions they lead 
to must be here given. 

Proofs of the Recent Occxtrreiice of a Gldcial Epoch, — The 
phenomena that prove the recent occurrence of glacial epochs 
in the temperate regions are exceedingly varied, and extend over 



102 .'■:■..■*• ISLAND LIFE. [?»«■ I. 

very wifhs-'areas. It will be well, therefore, to state, first, wliat 
those Jireiiare as exhibited in onr own country, referring after- 
Wftcde !o*Biiiiilar phenomena in other parts of the world, 
. PeyJiaps the most striking of nil the evidences of glsciatioii 
.*iO^*lio grooved, scratclied, or striated rocks. These occnr abiin- 
//li^ntlj in Scothind, Cnmberland, and Nortli Wales, and no ra- 
i.'tional explanation of them has ever been given except that tlicy 
were formed hy glaciers. In many valleys — us, for instance, thai 
of Llauherris, in North Wales^ — hondreds of examples may bo 
seen, consisting of deep grooves several inches wide, smaller fur- 
rows, and sti'iffi of extreme fineness wherever the rock is of suf- 
ficiently close and liard tcxtnrc to receive sueh marks. These 
grooves or seratches are often many jui-ds long ; thoy arc found 
in the bod of the valley as well as liigli u]) on its sides, and tliey 
arc almost all without exception in one general direction — that 
of the valley itself, even thongh the particular sni-face they arc 
upon sloiwa in aiiotlier direction. When the native covering of 
tnrf is cleared away from tie rock, the grooves and striie are often 
found in great perfection, and there is reason to believe that 
such markings cover, or have once covered, a liirge part of the 
snrface. Accompanying tlicse markings we find another hardly 
less curious phenomenon, the rounding-off or planing-down of 
the hardest rocks to a smooth undulating surface. Hard crys- 
talline schists with tlieii- strata nearly vertical, and which one 
would expect to find exposing jagged edges, ai-e found ground 
off to a perfectly smootli but never to a flat surface. These 
rounded surfaces are found not only on single rocks, but over 
whole valleys and mountain-sides, and form what are termed 
Toehea motitonnien, from their often having the appearance nt n 
distance of slicep lying down. 

Now these two phenomena are actually produced by existing 
glftciei'B, while there is no other known or even conceivable cause 
that could have produced them. Wlienever the Swiss glncioi's 
i-etreat a little, as they sometimes do, the rocks in the bed of the 
valley they have passed over are found to be rounded, grooved, 
and striated just as are those of Wales and Scotland. The two 
sets of phenomena are so exactly identical that no one who has 
ever compared tiiem can doubt that they are due to the same 



Cbap. YIL) 



THE OL&CIAL ETOCH. 



103 



cauEes. Btit we have fm-ther and even mnro convincing evi- 
dence. Glaciers produce many other effects besides these two ; 
and whatever effects they produce in Switzerland, in Norway, or 
in Greenland, we find examples of similar effects having been 
prodneed in our own country. Tlie most striking of tliese are 
moraines and travelled hloclcs. 




J/rtraiVt^*.— Almost every existing glacier carries down with 
it great masses of rock, stones, and earth, which fall on its sur- 
face from tlie pi-ecipices and mountain -sIoihib which hem it in, 
OP the rocky peaks which rise ahove it. As tlie glacier slowly 
i downward, this dt'bris forms long lines on each side, or 
on the centre whenever two glacier streams unite, and is depos- 
ited at its termination in a linge mound called the terminal mo- 
raine. The decrease of a glacier may often be traced by sncccs- 



104 



liiLAHD LIFE. 



[I'Al 



sivG old iiioriiiiies across tlie valley up which it lins retreated. 
AVlieii once eoeti and c:;iiinined, those moraines can always be 
distinguished almost at a glnnce. Their position is most re- 
markable, Imviiig no apparent natural ixilation to the form of 
the valley or the smTonnding slopes, so that they look like huge 
earthworks formed by man fur purposes of defence. Tiieir 
comijoeition is equally peculiar, consisting of a mixture of earth 
and rocks of all £i>:c3, usually without any arrangement, the 
rocks often being huge angular masses just as they had fallen 
from the surrounding precipices, Some of these rock masses 
often rest on the very lop of the moraine in positions where 
no other natnrul foree but that of ice could have placed them. 
Exactly similar mounds are found in tlic valleys of Nortli Wales 
and Scotland, and always where the other evidences of ice-action 
occur abundantly, 

Trai'dlfd Blocks. — The phenomenon of travelled or perched 
blocks is also a common one in all glacier countries, marking 
out very claarly the former extent of the ice, "When a glacier 
fills a lateral valley, its foot will sometimes ci'oss over the main 
valley and abut against its opposite slope, and it will deposit 
tlicre some portion of its terminal moraine. But in these cir- 
cumstances the end of the glacier, not being confined laterally, 
will spread out, and the moraine niatter will bo distributed over 
a large surface, so that the only well-marked token of its presence 
will bo the larger masses of rock that may have been brought 
down. Sncli blocks are found abundantly in many of the dis- 
tricts of our owu country where other marks of glaciation exist, 
and they often rest on ridges or liilloeks over which the ice has 
passed, these elevations consisting sometimes of loose material 
and sometimes of rock dlffere^it from that oficldeh the blocks are 
cojnposed. These arc called travelled blocks, and can almost al- 
ways be traced to their source in one of the higher valleys from 
which the glacier descended. Some of the must rcuDtrkable ex- 
amples of such travelled blocks are to be found on tlie soutliern 
elopes of the Jura. These consist of enormous angular blocks 
of granite, gneiss, and other crystalline rocks quite foi-eign to 
the Jura Mountains, but exactly agreeing with those of the Al- 
pine range fifty miles sway across the groat central valley of 



THE GLACUL EPOCH. 



105 



Switzerland. Oiio of the largest of these blocks \s forty feet in 
diameter, and is Bitimted 900 feut above the level of the Lake of 
NeufuhiTtel. These blocks have been proved by Swiss geologists 
to have been brought bj the ancient glacier of the Rhone, which 
was fed by the whole Alpine range, from Mont Blanc to tht. 
Furka Pass. This glacier must have been many thousand feet 




thick at the month of the Rhone volley near the head of the 
Lake of Geneva, since it spread over the whole of the great val- 
ley of Switserland, extending from <ieneva to JTeHfchatel, Berne, 
and Solenre, and even on the tlanks of the Jnra reached a max- 
imum height of 21)15 feet above the valley. Tlie numerous 
blacks scattered over the Jura for a distance of about a hundred 



ISLAND LIFE. 

miles vary considerably in tlie material of iviiicli tliey are com- 
poGed ; but they are fouTid to be each ti-aceable to a part of tho 
Aljia corresponding to their position, on the theory that they 
have been brought by a glacier spreading out from the Ghonc 
valley. Tims, all the blocks situated to the east of a central 
point G (see map) can be traced to the cnstcrn side of the lihone 
valley {I e rf), while those found towards Geneva have all come 
from the west side {p A). It is also very suggestive that the 
highest bloeka on the Jura at G have come from the eastern 
shoulder of Mont Blanc in the direct line A B F G. Here the 
glacier would naturally preserve its greatest thickness, wliile, as 
it spread out eastward and westward, it would become thinner. 
We accordingly find that the travelled blocks on either side of 
the central point become lower and lower, till near Soleure and 
Geneva they are not more than about 500 feet above the valley. 
The evidence is altogether 8o conclusive that, after personal ex- 
amination of the distrit't in eouij>any with eminent Swiss geolo- 
gists, Sir Charles Lyell gave up the view he had fii-st adopted— 
that the blocks had been carried by ice during a period of sub- 
inergcm^c— as altogether untenable' 

The phenomena now described demonstrate a change of cli- 
mate sufficient to cover all our higlier mountains with perpetual 
snow, and fill the adjacent valleys wilh huge glaciers at least as 
extensive ns those now found in Switzerland, But there are 
other phenomena, best developed in tho northern part of onr 
islands, which show that even this state of things was but the 
concluding phase of the glacial period, which, during its maxi- 
mum development, nmst have reduced the northern half of our 
island to a condition only to be paralleled now in Greenland 
and the antarctic regions. As few persons besides professed 
geologists arc acquainted with the weight of evidence for this 
gtaleineut, and as it is most important for our purpose to under- 
stand the amount of the cUmatal changes the Northern Ilemi- 
uphcre has undergone, I will endeavor to make the evidence in- 
telligible, referring my readers for full details to Dr. James 
Gcikie's descriptions and illustrations." 

' "Amiqnily orM«n."*tli cil.,pp. 3<0-3i3, 

' "Th« Great Ice Age nnd its Itolnlian to llio Aniiqniiv of Hon;" bv Jniura 
Geikie, F.B.S. (IhiMcr* Co., 1«'4.) 



Chap.VIL] the glacial EPOCH. 107 

Glacial Deposits of Scotland: the ^^ TiU.^^ — Over almost all 
the lowlands and in most of the highland valleys of Scotland 
there are immense superficial deposits of clay, sand, gravel, or 
drift, which can be traced more or less directly to glacial action. 
Some of these are moraine matter, others are lacustrine deposits, 
while others again have been formed or modified by the sea 
during periods of submergence. But below them all, and often 
resting directly on the rock surface, there are extensive layers of 
a very tough clayey deposit known as " till." The " till " is very 
tine in texture, very tenacious, and often of a rock-like hardness. 
It is always full of stones, all of which are of rude form, but 
with the angles rubbed off, and almost always covered with 
scratches and strice often crossing each other in various direc- 
tions. Sometimes the stones are so numerous that there seems 
to be only just enough clay to unite them into a solid mass ; and 
they are of all sizes, from mere grit up to rocks many feet in 
diameter. The " till " is found chiefly in the low-lying districts, 
where it covers extensive areas sometimes to a depth of a hun- 
dred feet; while in the highlands it occurs in much smaller 
patches, but in some of the broader valleys forms terraces which 
have been cut through by the streams. Occasionally it is found 
as high as 2000 feet above the sea, in hollows or hill-sides, where 
it seems to have l>een protected from denudation. 

The "till" is totally unstratified, and the rock surfaces on 
which it almost always rests are invariably worn smooth, and 
much grooved and striated when the rock is hard ; but when it 
is soft or jointed it frequently shows a greatly broken surface. 
Its color and texture, and the nature of the stones it contains, all 
correspond to the character of the rock of the district where it 
occurs, so that it is clearly a local formation. It is often found 
underneath moraines, drift, and other late glacial deposits, but 
never overlies them (except in special cases to be hereafter re- 
ferred to), so that it is certainly an earlier deposit. 

Throughout Scotland, where " till '* is found, the glacial striae, 
perched blocks, roches moutomiies, and other marks of glacial 
action occur very high up the mountains to at least 3000, and 
often even to 3500, feet above the sea, while all lower hills and 
mountains are rounded and grooved on their very summits; and 



108 



ISLAND LIFE. 



[PmwL 



these grooves alwaj's radiate outward from the liighest peaks 
and ridgea towards the valleys or the eea. 

Inferenoea front the Glucial Phenomena ofSooUand. — Xow all 
these phenomena, taken together, vender it certain that the wliole 
of Scotland waa uncc bnried in a vast eea of ice ont of wlticli 
only the highest mountains raised their summits. There is ab- 
solutely no escape from this conclusion ; for tho facts wliich lead 
to it arc not local — fonnd only in one spot or one valley — but 
general thronghout the entire length and breadth of Scotland; 
and are, besides, supported by such a mass of detailed corrobo- 
rative evidence as to amount to abeoluto demonstration. Tlie 
weight of this vast ice -shoot, at least 3000 feet in maximum 
thickness, and continually moving seaward with a slow gi-inding 
motion like that of all existing glaciers, must liave ground down 
the whole surface of the country, especially all the prominences, 
leaving tho rounded rocka as well as the grooves and strife we 
still sec marking the direction of its motion. All tho loose 
stones and rock masses which lay ou the surface would be 
pressed into the ice ; tlie harder blocks would servo as scratch- 
ing and grinding tools, and wonld thus themselves become 
rounded, scratched, and striated as we see tliem, while all the 
softer masses would be ground up into impalpable mud along 
with the material planed off the rocky projections of the coun- 
try, leaving them in the condition of rodiea trtouCmitiecs. 

The peculiar characters of tho " till," its fineness and tenacity, 
correspond closely with tho flue matter which now issues from 
under all glaciera, making the streams milky-while, yellow, or 
brown, according to the nature of the rock. The scdinient from 
sneli water is a fine unctuons sticky deposit, only needing press- 
ure to form it into a tenacious clay ; and when " till " is exposed 
to the action of water it dissolves into a similar soft sticky unct- 
uous mud. Tho present ghiciers of the Alps, being confined to 
valleys which carry off a largo quantity of drainage-water, lose 
this mud perhaps as rapidly as it is formed ; but when the ice 
covered the whole country there was comparatively littlo draiii- 
ngo-water, and thus the mud and stones collected in vast com- 
pact masses in all tho hollows, and especially in the lower flat 
valleys, so that when the ice retreated tho whole country was 



Chap.VIL] the glacial EPOCH. 109 

more or less covered with it. It was then, no doubt, rapidly de- 
nuded by rain and rivers ; but, as we have seen, great quantities 
remain to the present day to tell the tale of its wonderful for- 
mation.* There is good evidence that when the ice was at its 
maximum it extended not only over the land, but far out to sea, 
covering all the Scottish islands, and stretching in one connected 

^ This view of the formation of ** till *' is that adopted by Dr. Geikie, and upheld 
bj almost all the Scotch, Swiss, and Scandinavian geologists. The objection, how- 
ever, is made by many eminent English geologists, including Mr. Searles V. Wood, 
Jr., thnt mud ground off the rocks cannot remain beneath the ice, forming sheets of 
groat thickness, because the glacier cannot at the same time grind down t^olid rock 
and yet pass over the surface of soft mud and loose stones. But this difficulty will dis- 
appear if we consider the numerous fluctuations in the glacier with increasing size, 
and the additions it must have been constantly receiving as the ice from one valley 
after another joined togetlier, and at Inst produced an ice-sheet covering the whole 
country. The grinding power is the motion and pressure of the ice, and the pressure 
will depend on its thickness. Now the points of maximum thickness must have often 
changed their positions, and the result would be that the matter ground out in one 
place would be forced into another place where the pressure was less. If there were 
no lateral escape for the mud, it would necessarily support the ice over it, just as a 
water-bed supports the person lying on it ; and when there was little drainage-water, 
and the ice extended say twenty miles in every direction from a given part of a valley 
where the ice was of less than the average thickness, the mud would necessarily ac- 
cumulate at this part simply because there was no escape for it. Whenever the 
pressure all round any area was greater than the pressure on that area, the debris of 
the surrounding parts would be forced into it, and would even raise up the ice to give 
it room. This is a necessary result of hydrostatic pressure. Duiing this process the 
superfluous water would, no doubt, escape through Assures or pores of the ice, and 
would leave the mud and stones in that excessively compressed and tenacious condi- 
tion in which the **tiir* is found. The unequal thickness and pressure of the ice 
above referred to would be a necessary consequence of the inequalities in the valleys, 
now narrowing into gorges, now opening out into wide plains, and again n.-irrowed 
lower down ; and it is just in these openings in the valleys that the *^ till " is said to 
be found, and also in the lowlands, where an ice-sheet must have extended for many 
miles in every direction. In these lowland valleys the **tiir* is both thickest and 
most wide-spread, and this is what we might expect. At first, when the glaciers from 
the mountains pushed out into these valleys, they would grind out the surface be- 
neath them into hollows, and the drainage- water would carry away the debris. But 
when they spread all over the surface from sea to sea, and there wns little or no 
drainage- water compared to the enormous area covered with ice, the great bulk of 
the de'bris must gather under the ice wherever the pressure was least, and the ice 
would necessarily rise as it accumulated. Some of the mud would, no doubt, be forced 
out along lines of least resistance to the sea, but the friction of the stone-charged 
'* till " would be so enormous that it would be impossible for any large part of it to 
be di^KMed ot in this way. 



110 



ISLAND LIFE. 



[Pam I. 



Gheet to Ireland and Wales, wliere all the evidences of glaciation 
are as well marked a& in Scotlund, thongh the ice did not, of 
course, attain quite so great a tliickness," 

It is evident that the change of cliuiato I'oquisito to jiroduco 
sncli marvelloDs effects in tho Britisli Islea could uot have been 
local, and we accoi-dingly find strikingly similar proofs that 
Scandinavia and all Nortlicrn Kuropo have also been covered 
with a hngo ice-sheet; while wc have already seen that a sim- 
ilar gigantic glacier buried tho Alps, carrying granitic blocks to 
the Jura, wlicro it deposited them at a height of 3150 feet above 
the sea ; white to tlie south, in tho plains of Italy, the terminal 
moraines left by the retreating glaciere have formed extensive 
hills, those of Ivrea, the work of the great glacier from the Val 
d'Aosta, being 15 miles across, and from 700 to 1500 feet high. 

Glacial Pkentymena in North America. — In North America 
the marks of glaciation ara even more extensive and striking 
than in Europe, stretching over the whole of Canada and to the 
south of tlio Great Lakes as far as latitude S'i", There is in all 
these countries a wide-spread deposit like the " till" of Scotland, 
produced by the grinding of the great ice-sheet when it was at 
its maxlmnni thickness; and also extensive beds of moraine- 
matter, true moraines, and travelled blocks, left by the glaciers 
as they retreated towai-da tho mountains and finally withdrew 
into tho upland valleys. There are also, both in Britain, Scan- 
dhiavia, and North America, proofs of the submersion of tho 
land beneath the sea to a depth of upwards of a thousand feet; 
but this is ft subject we need not here enter upon, ns our special 
object is to show the reality and amount of that wondei-ful and 
comparatively recent change of climate termed the glacial epoch. 

Many persons, even among scientific men, who have uot given 



Ireland it prored by tlie 
iniliii' ro ihRt in Smllnnil 
ne rrnm Citmberlnnd mid 



' Tlint ilie icc-slicci uoa continuoui froin Scoilund ci 
glncial phenoDicna in the Isle of Man, vlier« "till" i 
nboiintlfi, and rocki nre found in it which must hnve ec 
Scodind. lu nell ns from Iho Nonh of Ireland. This would show (h&t glncien ftum 
enrh of thuic districu readied the Iile of Man, where ihey met and flotred M>nlll- 
wnrd doivn ihe Irish Ken. Ini-mnrkii are inieed over tho top* of (he munn'nini. 
which are nearly S000fa«t high. (See "A Sketch of ilic GeoloKy of the Iile of 
Mnn," by John Home, F.G.S., THntactioat iff the Edinburi/k Utohgkat Saeieti/, 
Vol. U.,1'1. ill., 1874.) 



Chap. VII.] THE GLACIAL EPOCH. Ill 

much attention to the question look upon the whole subject of 
the glacial epoch as a geological theory made to explain certain 
phenomena which are otherwise a puzzle ; and they would not 
be much surprised if they were some day told that it was all a 
delusion, and that Mr. So-and-so had explained the whole thing 
in a much more simple way. It is to prevent my readers being 
imposed upon by any such statements or doubts that I have 
given this very brief and imperfect outline of the nature, extent, 
and completeness of the evidence on which the existence of the 
glacial epoch depends. There is perhaps no great conclusion 
in any science which rests upon a ^urer foundation than this; 
and if we are to be guided by our reason at all in deducing the 
unknown from the known, the past from the present, we cannot 
refuse our assent to the reality of the glacial epoch of the 
Northern Hemisphere in all its more important features. 

Effects of the Glacial Epoch on Animal Life: Warm and 
Cold Periods. — It is hardly necessary to point out what an im- 
portant eflFect tills great climatal cycle must have had upon all 
living things. When an icy mantle crept gradually over much 
of the Northern Hemisphere till large portions of Europe and 
North America were reduced to the condition of Greenland 
now, the greater part of the animal life must have been driven 
southward, causing a struggle for existence which must have led 
to the extermination of many forms, and the migration of oth- 
ers into new areas. But these eflFects must have been greatly 
multiplied and intensified if, as there is very good reason to be- 
lieve, the glacial epoch itself — or at least the earlier and later 
phases of it — consisted of two or more alternations of warm and 
cold periods. 

The evidence that such was the case is very remarkable. The 
" till," as we have seen, could only have been formed when the 
country was entirely buried under a large ice-sheet of enormous 
thickness, and when it must therefore have been, in all the parts 
so covered, almost entirely destitute of animal and vegetable 
life. But in several places in Scotland fine layers of sand and 
gravel, with beds of peaty matter, have been found resting on 
" till " and again covered by " till." Sometimes these interca- 
lated beds are very thin, but in other cases they are twenty or 



ISLAND IJ?E. 



[P»»Tl. 



thirty feet thick, and in them have been found remains of the 
extinct ox, tlie Irish elk, the horse, reindeer, and mammoth. 
Here we have evidence of two distinL-t periods of intense cold, 
and an intervening milder period snfficiently prolonged for tlie 
country to become covered with vegetation and stocked with 
animal life. In some dietncte borings have proved the cxiet- 
cnce of no less than fonr distinct formations of "till" sepamtcd 
from each other bj beds of sand from two to twenty feet in 
thickness.' Facta of a similar nature have been observed in 
other piirts of our islands. In the East of England, Mr. Skertchly 
(of the Geological Survey) enumerates four distinct boulder 
elays with intervening deposits of gravels and sands.' Mr. 
Searles V. Wood, Jr., classes the most recent (Ilesale) boulder 
day as " postglacial ;" but he admits nn intervening wai-mer 
period, chai-acterized by southern forms of mollusca and insects, 
after which glacial eouditious again prevailed with northern 
types of inol!usea.' Elsewhere bo says, "Looking at the pres- 
ence of snob flnvtatile mollusca as C'l/reva Jiuniinalie and tJmo 
lUtoralis. and of such mammalia as the hippopotamus and other 
great pachyderms, and of such a littoml Lnsitanian fauna as 
that of the Selsea bed, where it is mixed up with the remains of 
some of those pachyderms, as well as of some other features, it 
has seemed to mo that the climate of the earlier part of the 
postglacial period in England was possibly even warmer than 
our prci^^nt climate; and that it was succeeded by a refrigera- 
tion eutlicieDtly severe to cause ice to form all round onr coasts, 
and glaciers to accumulate in the valleys of the monntain dis- 
tricts; and that tliis increased severity of climate was preceded 
and partiiilly accompanied by a limited submergence, which no- 
whore apiiarently exceeded 300 feet, and reached that amount 
only ill the noitliern counties of England."* This decided ad- 



• "The Gi'pni 1m Ako,"p. 1T7. 

' Theso nic nnmod, in dcscemling orJer, Ileule lloiilder Clnr, I'uqile B<jtild< 
Clnj, Cholk^ Boulder <?lnj, nnd Loner Boulder CIny, below wliidi is iliu Nomic 

'"On lliB rlimate of the I'osiglniiiil reiiod," Crolnt/k-iit Mii'ja:inr, 1872, |i] 

ir«, iGo. 

* timhyiml Magntinr, 1871!, p. ^tHl. 



Chap. VII.] THE GLACIAL EPOCH. 113 

mission of au alternation of warm and cold climates since the 
height of the glacial epoch by so cautious a geologist as Mr. 
Wood is very important, as is his statement of an accompany- 
ing depression of the land accompanying the increased cold, be- 
cause many geologists maintain that a greater elevation of the 
land is the true and sufficient explanation of glacial periods. 
Further evidence of this alternation is found both in the Isle of 
Man and in Ireland, where two distinct boulder claj's have been 
described with intervening beds of gravels and sands. 

PaXmontological Evidence of Alternate Cold and War?n Peri- 
ods. — Especially suggestive of a period warmer than the pres- 
ent, immediately following glacial conditions, is the occurrence 
of the hippopotamus in caves, brick-earths, and gravels of palae- 
olithic age. Entire skeletons of this animal have been found at 
Leeds in a bed of dark-blue clay overlaid by gravel. Farther 
north, at Kirkdale cave, in N. lat. 54° 15', remains of the hippo- 
potamus occur abundantly along with those of the ox, elephant, 
horse, and other quadrupeds, and with countless remains of the 
hyenas which devoured them; while it has also been found* in 
cave-deposits in Glamorganshire, at Durham Down, near Bris- 
tol, and in the post-Pliocene drifts of Dorsetshire. It is impor- 
tant to note that where it is associated with other mammals in 
caves — which are hyena -dens, and not mere receptacles of 
water-earned remains — these always imply a mild climate, the 
elephant and rhinoceros found with it being species character- 
istic of temperate latitudes {Elep/tas antiquus and Rhinoceros 
heniiteechus). But when it occurs in gravels or in water-borne 
cave-deposits it is sometimes associated with the mammoth, the 
woolly rhinoceros, and the reindeer — animals which as certainly 
imply a cold or even arctic climate. This diflFerence is intelli- 
gible if we consider that the hyena, which carried the bones of 
all these animals into the caves, is itself indicative of a mild 
climate, and that there is nothing to cause the remains of ani- 
mals of successive epochs to be intermingled in such caves. In 
the gravels, however, it is very different. During the warm 
periods the rivei*s would be inhabited by hippopotami, and the 
adjacent plains by elephants and horses, and their remains would 
be occasionally embedded in deposits formed during floods. 

8 



114 



ISLAND LIFE. 



[Pjii 



But when the (.'old period came on. and these had passed south- 
ward, the same nver-bnnks would be grazed \>y mammotliB and 
reindeer whose remains would soinetinies intertningle witli those 
of the aiiiuials which preceded tliem. It is to bo noted, also, 
tliat in niauy of these river-deposits tliere are proofs of violent 
iloods causing much rearrangement of materials, so that the 
remains of the two periods would be tima still further inter- 
mingled,' 

The fact of the hippoiiotainus having lived at 54° N. lat. in 
England, quite close to the time of the glacial epoch, is abso- 
lutely incousistent with a mere gradual amelioration of climate 
from that time till the present day. The immense quantity 
of vegetable food which this creature requires implies a mild 
and uniform climate with hardly any acvero winter; and no 
theory that haa yet been suggested renders this possible except 
that of alternate cold and warm periods during the glacial epoch 
itself. In order that the hippopotamus could have reached 
Yorkshire and retired again as the climate changed, we may 
suppose it to have been a permanent inhabitant of the Lower 
Khonc, between which river and the Khine there is an easy 
communication by means of the Doubs and the 111, some of 
whose tributaries approach within a mile or two of each other 
about fifteen miles sontliwest of MiiUiausen, Theuce the pas- 
sage would be easy down the Rhine into the great river which 
then flowed up the bed of the North Sea, and thence up the 
Ilumber and Ouse inio Yorkshire. By this route there would 
be only one water -sited to cross, and this might probably 
have been marshy ; but we may also suppose tlie animals to 
liave ascended the Bristol Channel after passing round a long 
extent of French and English coast (whith would tlien have 
consisted of vast plains stretching far beyond the Scilly Isles), 
in which case they would find an equally easy ]>aaeage over a 
low water-slicd from the valley of the Avon to that of the Trent 
and Yorkshire Ouse. A consideration of tlie long and circui- 
tous journey required on any hypothesis will at once convince 



' A, Tjlor, on "Qunieinary Gn 
••/London, \W3, ]>i>. »3, D.'. (wood-ci 



arttrly Jeitnial «f Gtalagiail Socitig 



Chap. VII.] THE GLACIAL EPOCH. 115 

ns tbat it could never have been made (as some have supposed) 
annually during the short hot summer of the glacial period it- 
self ; whereas the interglacial warm periods lasting several thou- 
sand years would allow for the animals' gradual migration into 
all suitable river valleys. Thus, the very existence of the hip- 
popotamus in Yorkshire as well as in the South of England, in 
close association with glacial conditions, must be held to be a 
strong corroborative argument in favor of the reality of an in- 
terglacial warm period. 

Evidence of Interglacial Warm Periods on the Continent and 
in North America. — Besides the evidence already adduced from 
our own islands, many similar facts have been noted in other 
countries. In Switzerland two glacial periods are distinctly rec- 
ognized, between which was a warm period when vegetation 
was so luxuriant as to form beds of lignite sufficiently thick to 
be worked for coal. The plants found in these deposits are sim- 
ilar to those now inhabiting Switzerland — pines, oaks, birches, 
larch, etc. ; but numerous animal remains are also found, show- 
ing that the country was then inhabited by an elephant {Ele- 
phas antiquus), a rhinoceros {lihinoceros Etru8cus\ the urns 
{Bo8 primigenius\ the red deer {Cervus elephas\ and the 
cave-bear {Ursula spel<BU8)\ and there was also abundance of 
insects.* 

In Sweden also there are two " tills," the lower one having 
been in places partly broken up and denuded before the upper 
one was deposited, but no interglacial deposits have yet been 
found. In North America more complete evidence has been 
obtained. On the shores of Lake Ontario sections are exposed 
showing three separate beds of " till" with intervening stratified 
deposits, the lower one of which has yielded many plant re- 
mains and fresh-water organisms. These deposits are seen to 
extend continuously for more than nine miles, and the fossilif- 
erous inter«:lacial beds attain a thickness of 140 feet. Similar 
beds have been discovered near Cleveland, Ohio, consisting, first, 
of " till " at the lake-level ; secondly, of about forty-eight feet of 
sand and loam ; and, thirdly, of unstratitied "till " full of striated 

» Hecr'8 " PrimaevalWorld of SwitzerUnd," VoL XL, pp. 14a-I68. 



116 



ISLAND LIFE. 



stones, six feet tliic-k." On tlia other Bide of the continent, in 
Dritish Columbia, Mr. G. M. Dawson, geologist to the North 
American Bonndnry Commission, has discovered similar evi- 
dence of two glaciations divided from eadi other by a warm 
period. 

This remarkable Beries of observations, spretid over so wide 
an area, Beema to affoi-d ample proof that the glacial epoch did 
not consist merely of one proCMJSs of dmiige from a temperate 
to a cold and arctic climate, which, having reached a masinmm, 
then passed slowly and completely away, but that there were 
certainly two, and probably several more, alternations of arctic 
and temperate climates. 

It is evident, however, that if there have been, not two only, 
but a series of such alternations of climate, we could not pos- 
sibly expect to find more than the most slender indications of 
them, becansc each sncceeding ice-sheet would necessarily grind 
down or otherwise destroy much of the superficial deposits left 
by its predecessors, while the torrents that must always liave ac- 
companied the melting of these huge masses of ice would wash 
away even such fragments as might have escaped the ice itself. 
It is a fortunate thing, therefore, that wo should find any frag- 
ments of these intcrglacial deposits containing animal and veg- 
etable remains ; and, just as we should expect, the evidence they 
afford seems to show that the later phase of the cold period was 
less severe than the eaiiicr. Of such deposits ns were formed 
on land during the eoming-on of the glacial epoch, when it was 
continually increasing in severity, hardly a tiuee lias been pre- 
served, because each succeeding extension of the ice, being 
greater and thicker than llie last, destroyed what had gone bo- 
fore it till the maximum was reached. 

Mi'jra/irma aiid Extinction of Organisms Caused by the Gla- 
cial Epoch. — Our last glacial epoch was accompanied by at least 
two considerable Bubmergences and elevations of the land, and 
there is some reason to think, as we have already explained, that 
the two classes o( phenomena are connected ns cause and effect. 
We can easily see how snch repeated submergences and eleva- 



Chap. VII.] THE GLACIAL EPOCH. 117 

tious would increase and aggravate the migrations and extinc- 
tions that a glacial epoch is calculated to produce. "We can 
therefore hardly fail to be right in attributing the wonderful 
changes in animal and vegetable life that have occurred in Eu- 
rope and North America between the Miocene period and the 
present day, in part at least, to the two or more cold epochs that 
have probably intervened. These changes consist, first, in the 
extinction of a whole host of the higher animal forms; and, sec- 
ondly, in a complete change of types due to extinction and emi- 
gration, leading to a much greater diflFerence between the vege- 
table and animal forms of the Eastern and Western hemispheres 
than before existed. Many large and powerful mammalia lived 
in our own country in Pliocene times, and apparently survived 
a part of the glacial epoch ; but when it finally passed away, they 
too had disappeared, some having become altogether extinct, 
while others continued to exist in more southern lands. Amono: 
the first class are the sabre-toothed tiger, the extinct Siberian 
camel (Merycotherium), three species of elephant, two of rhinoc- 
eros, a hippopotamus, two bears, five species of deer, and the gi- 
gantic beaver ; among the latter are the hyena, bear, and lion, 
which are considered to be only varieties of those which once 
inhabited Britain. Down to Pliocene times the flora of Europe 
was very similar to that which now prevails in Eastern Asia and 
Eastern North America. Hundreds of species of trees and 
shrubs of peculiar genera which still flourish in those countries 
are now completely wanting in Europe ; and we have good rea- 
son to believe that these were exterminated during the glacial pe- 
riod, being cut off from a southern migration, first by the Alps, 
and then by the Mediterranean ; whereas in Eastern America 
and Asia the mountain-chains run in a north and south direc- 
tion, and there is nothing to prevent the flora from having been 
preserved by a southward migration into a milder region. 

Our next two chaptei*8 will be devoted to a discussion of the 
causes which brought about the glacial epoch, and that still more 
extraordinary climatic phenomenon — the mild climate and luxu- 
riant vegetation of the arctic zone. If my readers will follow 
me with the care and attention so diflScult and interesting a prob- 



118 ISLAND LIFE. [Part I. 

leni requires and deserves, they will find that I have grappled 
with all the facts which have to be accounted for, and offered 
what I believe is the first complete and sufficient explanation of 
them. The important influence of climatal changes on the dis- 
persal of animals and plants is a sufficient justification for in- 
troducing such a discussion into the present volume. 



Chap.VIIL] the causes OF GLACIAL EPOCHS, 119 



CHAPTER VIII. 

THE CAUSES OF GLACIAL EPOCHS. 

Various Suggested Causes. — Astronomical Causes of Changes of Climate. — Differ- 
ence of Temperature Caused bj Varying Distance of the Sun. — Properties of Air 
and Water, Snow and Ice, in Kelation to Climate. — Effects of Snow on Climate. — 
High Land and Great Moisture Essential to the Initiation of a Glacial Epoch. — 
Perpetual Snow nowhere Exists on Lowlands. — Conditions Determining the Pres- 
ence or Absence of Perpetual Snow. — Efficiency of Astronomical Causes in Pro- 
ducing Glaciation. — Action of Meteorological Causes in Intensifying Glaciation. 
— Summary of Causes of Glaciation. — Effect of Clonds and Fog in Cutting off the 
Sun*s Heat. — South Temperate America as Illustrating the Influence of Astronomi- 
cal Causes on Climate. — Geo£p*aphical Changes, how far a Cause of Glaciation. — 
Land Acting as a Bamer to Ocean Currents. — The Theory of Interglacial Peiiods 
and their Probable Character. — Probable Effect of Winter in Aphelion on the Cli- 
mate of Britain. — The Essential Principle of Climatal Change Restated. — Pi*ob- 
able Date of the Last Glacial Epoch. — Changes of the Sea-level Dependent on 
Glaciation. — The Planet Mars as Bearing ^n the Theory of Eccentricity as a 
Cause of Glacial Epochs. 

No less than seven diflEerent causes have been at various times 
advanced to account for the glacial epoch and other changes of 
climate which the geological record proves to have taken place. 
These, as enumerated hy Mr. Searles V. Wood, Jr., are as fol- 
lows : 

1. A decrease in the original heat of our planet. 

2. Changes in the obliquity of the ecliptic. 

3. The combined eflFect of the precession of the equinoxes 
and of the eccentricity of the earth's orbit. 

4. Clianges in the distribution of land and water. 

5. Changes in the position of the earth's axis of rotation. 

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

7. A variation in the temperature of space. 

Of the above, causes 1 and 2 are undoubted realities ; but 
it is now generally admitted that they are utterly inadequate 



ISLAND LIFE. 



tPi-tJ. 



to produce the observed effects. Ouses 5, G, and 7 are all 
purely liypotbetical ; for, though eucli changes may have occur- 
ved, tlierc is no evidence that they have oecnrrod during geolog- 
ical time, and it is, besides, certain that they would not, either 
singly or combined, be adequate to explain the whole of the 
phenomena. Thci-e remain cqubcb 3 and 4, which have the 
advantage of being demouBtrated facts, and which are univer- 
sally admitted to be eapabie of producing «oni* effect of the nat- 
ure required, the only question being whether, cither alone or 
in combination, they are adequate to produce all the observed 
effects. It ia tlicrefore to these two causes that we shall con- 
fine our inquiry, taking first those astronomical causes whose 
complex and wide-reaching effects have been so admirably ex- 
plained and discussed hy Dr. CtoII in numerous papers and in 
his work " Climate and Time in tiieir Geological Relations." 

Astronomical Causes of Changes ofClimatf. — The earth moves 
in an elliptical orbit round the sun, which is situated in one of 
the foci of the ellipse, so that tlie distance of the suu from ua 
varies during the year to a considerable amount. Strange to 
say, we are now three millions of miles nearer to the sun in win- 
ter than in summer, while the reverse is the case in the South- 
ern Hemisphere ; and this must have some effect in making our 
northern winters less severe than those of the south temperate 
zone. Hut the earth moves more rapidly in that part of its 
orbit which is nearer to the sun, so that our winter is not only 
milder, but several days shorter, than that of the Southern 
Hemisphere. The distribution of land and sea and other local 
causes prevent us from making any accurate estimate of the 
effects due to these differences; but there can be no doubt that 
if our winter were now !is long as our summer, and we were also 
three million miles farther from the son at the former period, 
a very decided difference of climate would result — our winter 
would he colder and longer, our summer hotter and shorter. 
Now tliere is a eombinalion of astronomical revolutions (the 
precession of the equinoxes ami the motion of the aphelion) 
which actually brings this change about every 10,500 years, so 
that after this interval the condition of the two hemispheres is 
reversed as i-egflrds nearness to the sun in sumnicr, and com- 



Chap. VIIL] • THE CAUSES OF GLACIAL EPOCHS. 121 

parative duration of summer and winter; and this change has 
been going on throughout all geological periods. (See diagram.) 
The influence of the present phase of precession is perhaps 
seen in the great extension of the antarctic ice-fields, and the 
existence of glaciers at the sea-level in the Southern Ilemisphere 
in latitudes corresponding to that of England ; but it is not sup- 
posed that similar effects would be produced with us at the 
last cold period, 10,500 yeai*s ago, because we are exceptionally 
favored by the Gulf Stream warming the whole North Atlantic 
Ocean, and by the prevalence of westerly winds which convey 
that warmth to our shores ; and also by the comparatively small 
quantity of high land around the North Pole, which does not 

N.HEMISPHERE WINTER IN APHELION S .HEMISPHCRC WMTER IN APHELION 





GLACIAL EPOCH IN GLACIAL EPOCH IN 

NJIEMISPHERC 8.HEMISPHERC 

DIAGRAM 8H0WIN0 THE ALTERED POSITION OF THE POLES AT INTERVALS OF 10,500 
YEARS PRODUCED BT THE PRECESSION OF THE EQUINOXES AND THE MOTION OF 
THE APHELION; AND ITS EFFECT ON CLIMATE DURING A PERIOD OF IIIUH EC- 
CENTRICITY. 

encourage great accumulations of ice. But the amount of eccen- 
tricity itself varies very largely, though very slowly, and it is 
now nearly at a minimum. It also varies very irregularly ; but its 
amount has been calculated for several million years back. Fifty 
thousand years ago it was rather less than it is now ; but it then 
increased, and when we come to a hundred thousand yeare ago, 
there is a diflFerence of eight and a half millions of miles between 
our distance from the sun in aphelion and perihelion (as the 
most distant and nearest points of the earth's orbit are termed). 
At a hundred and fifty thousand yeai-s back it had decreased 
somewhat — to six millions of miles; but then it increased again, 
till at two hundred thousand years ago it was ten and a quarter, 
and at two hundred and ten thousand vears ten and a half, mill 



ISLAND UFE. 



[PjuwI. 



ions of uiilea- By reference to tlio accompanying diagram, which 
itidiidGS the last great period of eceentrioity, we tiud that for 
the irumcusc period of a hundred and sixty thoiiEaud years 
(commencing about eighty thousand years ago) the eccentricity 
wiis very great, reaching a maximum of three and a half times 
its present amount at almost the remotest part of this period, at 
which time the length of summer in one hemisphere and of 
winter in the other would be ncai'ly twenty-eight days iu excess. 



rPROBULE DURATION OF TXE CLACIAL EPOCH^ 




Tlie ilark mid li^bt bands miiik ihe p)in»ei of |ireceuion, the dark Bhouing ilinrt 
mild wintera, nnd tlis lieht Icing cold winten, ilie conti'i»t being grcnier aa the 
ecMiitricit}^ IB liiRher. The lioiiioniAl dotted line mnrki llio present eccenlricitr. 
'i'lie Hgares show ilie Rinximn and minima of eccenlriciij duiing ilie liist 3UO,000 
jenrg Fiom Dr. Crolls laUen. 

Now during all this time our position would cliange, as al>ove 
described (and as indicated on the diagram), every ten thousand 
five hundred years ; so that we should have iilteniate periods of 
very long and cold winters with short hot sunnners, and short 
mild winters with long cool Eumniers, In order to undorataiid 
the important elleets which this would produce, we must ascer- 
tain two things — first, what actual difference of temperature 
would he caused by varying distiinces of the sun ; and, secondly, 
what are the properties of snow and ice in regard to climate. 

Diferenix tif Tewpei'ature Cuy«fi/ bi/ Vaci/itiff Di^taticfs qfth^ 
Sitn. — On this subject comparatively few persona have correct 



Chap. VIII.] THE CAUSES OF GLACIAL EPOCHS. 123 

ideas, owing to the unscientific manner in which wo reckon 
heat by our thermometei*s. Our zero is thirty-two degrees be- 
low the freezing-point of water, or, in the centigrade thermom- 
eter, the freezing-point itself, both of which are equally mislead- 
ing when applied to cosmical problems. If we say that the 
mean temperature of a place is 50° F. or 10° C, these figures 
tell us nothing of how much the sun warms that place, because 
if the sun were withdrawn the temperature would fall far be- 
low either of the zero-points. In the last arctic expedition a 
tempemture of —74° F. was registered, or 106° below the freez- 
ing-point of water ; and as at the same time the earth, at a depth 
of two feet, was only —13° F. and the sea-water -f28° F., we 
may be sure that even this intense cold was not near the possi- 
ble minimum temperature. By various calculations and experi- 
ments which cannot be entered upon here, it has been deter- 
mined that the temperature of space, independent of solar (but 
not of stellar) influence, is about —239° F., and physicists al- 
most universally adopt this quantity in all estimates of cosmical 
temperature. It follows that if the mean temperature of the 
earth's surface at any time is 50° F., it is really warmed by the 
sun to an amount measured by 50 + 239 = 289° F., which is 
hence termed its absolute temperature. Now during the time 
of the glacial epoch the greatest distance of the sun in winter 
was 97^ millions of miles, whereas it is now, in winter, only 91 
millions of miles. But the quantity of heat received from the 
sun is inversely as the square of the distance, so that it would 
then be in the proportion of 8281 to 9506 now, or nearly one 
eighth less than its present amount. The mean temperature of 
England in January is about 39° F., which equals 278° F. of ab- 
solute temperature. But the above-named fraction of 278° is 
36°, representing the amount which must be deducted to obtain 
the January temperature during the glacial epoch, which will 
therefore be 3° F. Our actual temperature at that time might, 
however, have been very diiferent from this, because the tem- 
perature of a place does not depend so much on the amount of 
heat it receives directly from the sun as on the amount brought 
to it or carried away from it by warm or cold winds. We often 
have it bitterly cold in the middle of May when we are receiv- 



ISLAND LIFE. 



[PiBiL 



i[ig as iinicSi sim lieat as many parts of the tropics, because we 
get cold winds from the iceberg-ladeu North Atlantic, and this 
partially neutralizes the effect of the eun. So wc often bave it 
very mild in December if son tli westerly winds bring uB warm 
moist nir from the Gulf Stream. Hut though the above method 
does not give correct results for any one time or place, it is 
more nearly correct for very large areaci, because all the sensible 
surface heat which produces climates comes from the sun, and 
its proportionate amount may be very nearly calculated in the 
manner above described. We may therefore say, generally, that 
during our iiortliorn winter, at t!ie time of the glacial epoclj, 
the Northern Hemisphere was receiving bo much less heat from 
the sun as to lower ils surface teinperatiii-e on an average about 
35° F., while during tlie height of summer of the same period 
it would be receiving so much more heat as would snffice to 
raise its mean temperature abont 00* F. above what it is now. 
The winter, however, would be long and the snuimer short, tlie 
difference being twenty-six days. 

We Iiavc here certainly a superabundant amonnt of cold in 
winter to produce a glacial period,' especially as this cold would 



' In a letier lo JVafunt of Oclober 30, 1 @T'J, the Itcv. O, FJ^^Iier mils ntCeniJon to n 
resnlt an-ived nt by I'oulUat. that tlio lenipeiiitLii'e uliicli ihe miriuca of nie graunil 
would OBsurao if the sun were exlinguialieil would L>e —138" F. iiisiend of —iSd" F. 
If iliii corrected nmoaiil ncrc ntcd in our cnlcuin lions, ilio Jnnimr}' tcmperalura of 
Enslnnd duving the gincini epoch would come out 17° F., and llii) Mr. Fialiei' tiiiiika 
not low cnnDgh to canto nny cxireme iliffercnce from the present climnte. In thia 
opinion, lioweTor, I unnot ngive wUh htin. On (he contrar}'. it would, I iliiuk, be 
A relief to the theory wera tlic nroonnts of decrcnso of lamperilure in nioter nnd in- 
crenw in summer rondei-od moid mudernte, litice nccording to llio ubuoI calculation 
(which I have ndnpied) the dilTei-cncei nro unnctiesE^iirily great. I cniiuot, iliererore, 
think that iliia tnodilieaiion of (lie lempemtnres. ihontd it be uliironiely proied to be 
eon'«et (nhich in nitogeiher denied lit Dr. Croll), would be nny seiioua objeciioii In 
the adoption of Dr. CroU'i theory of llic nslronomicnl nnd phiftical ciiu*ea of the 
glHcial epoch. 

The renaon of ihe increnie of ■nmmcr hent being CiO", while )be decnea«e of winter 
cold is only 3u', is because our lummer is now btloa nnd onr winler aiiane the aver- 
age. A large part of Uic W increase of lemperntin'e wouiil, no donbt, be lued up in 
erapomting wiiter, so that there would be a much leu iiici-case of senniblc hem ; 
while only n poiiion of iho 30" lonciing of lemjietniure in niiiier uould be nciunlly 
prodnced, oHing lo eqnnlixing effect of winds nnd currents nnd ihe tloring-up of 
hcnt bv Ihe cnitli nnd ocean. 



Chap.VIIL] the causes OF GLACIAL EPOCHS. 125 

be long continued ; but at the same time we sliould have almost 
tropical heat in summer, although that season would be some- 
what shorter. How, then, it may be asked, could such a climate 
have the effect supposed? Would not the snow that fell in 
winter be all melted by the excessively hot summer? In order 
to answer tliis question, we must take account of certain proper- 
ties of water and air, snow and ice, to which due weight has not 
been given by writers on this subject. 

Properties of Air and Water ^ Snow and Ice^ in Helation to 
Climate. — The great aerial ocean which surrounds us has the 
wonderful property of allowing the heat-i-ays from the sun to 
pass through it without its being warmed by them ; but when 
the earth is heated the air gets warmed by contact with it, and 
also to a considerable extent by the heat radiated from the warm 
earth, because, altliough pure dry air allows such dark heat-rays 
to pass freely, yet the aqueous vapor and carbonic acid in the 
air intercept and absorb them. But the air thus warmed by 
the earth is in continual motion, owing to changes of density. 
It rises up and flows off, while cooler air supplies its place ; and 
thus heat can never accumulate in the atmosphere beyond a 
very moderate degree, the excessive sun heat of the tropics being 
much of it carried away to the upper atmosphere and radiated 
into space. Water also is very mobile ; and although it receives 
and stores up a great deal of heat, it is forever dispersing it over 
the earth. The rain, which brings down a certain portion of 
heat from the atmosphere, and which often absorbs heat from 
the earth on which it falls, flows away in streams to the ocean ; 
while the ocean itself, constantly impelled by the winds, forms 
great currents, which carry off the surplus heated water of the 
tropics to the temperate and even to the polar regions, while 
colder water flows from the poles to ameliorate the heat of the 
tropics. An immense quantity of sun heat is also used up in 
evaporating water, and the vapor thus produced is conveyed by 
tlie aerial currents to distant countries, where, on being con- 
densed into rain, it gives up much of this heat to the earth and 
atmosphere. 

The power of water in carrying away heat is well exhibited 
by the fact of the abnormally high temperature of arid deserts 



ISLAND LIFE. 



[Paw I. 



and of very dry countries geiieriilly; while tlie still more pow- 
erful influence of moving nir may be appreciated by cousider- 
ing tlie effects of even our northern sun in heating a tightly 
closed glass house to far above the temperature produced by the 
vertical sun of the eqnator, wlicre the free air and abundance of 
moisture exert their beneficial influence. Were it not for the 
large proportion of the sun'a heat carried away by air and water, 
the tropics would become uninhabitable furnaces; ae would, in- 
deed, ajiy part of the earth where the fliin shone brightly throngh- 
out a Buinmer's day. 

We see, therefore, tliat the excess of lieat derived from the 
snn at any place cannot be stored up to aii important amount 
owing to the wonderful dispersing agency of air and water ; and 
though some heat does penetrate the ground and ie stored up 
there, this is so little in proportion to the whole amount re- 
ceived, and the larger part of it is so soon given out from the 
surface layers, that any surplus heat that may be thus preserved 
during one snromer rarely or never remains in sufficient quanti- 
ty to affect the temperature of the succeeding summer, so that 
there is no such thing as an accnmulatioii of earth heat from 
year to year. Unt though heat cannot, cold can be stored up 
to an almost unlimited amount, owing to the peculiar property 
water possesses of Incoming solid at a moderately low tempera- 
ture ; and as this is a subject of the very greatest importance to 
niir inquiry — the whole (question of the possibility of glacial 
ppocha and warm periods depending on it — we must consider it 
in some detail. 

liffixi^ of Snmci on Climate. — Let ns, then, examine the very 
diffei'cnt effects produced by water falling as a liqnid in the 
form of rain, or as a solid in the form of snow, although the 
two may not differ from each otiier more than two or three de- 
grees in temperature. The rain, however much of it may fall, 
runs off rapidly into streams and rivers, and soon reaches the 
ocean. If cold, it cools the air and the earth somewhat while 
passing tlirongh or over them, but produces no permanent effect 
on temperature, because a few hours of sunshine restore to the 
air or the eurfaec soil all the heat they had loRt. Ihit If snow 
falls for a long lime, the effect, as wo all know, is very different, 



Chap. VIII.] THE CAUSES OF GLACIAL EPOCHS. 127 

because it has no mobility. It remains where it fell and becomes 
compacted into a mass, and it then keeps the earth below it and 
the air above at or near the freezing-point till it is all melted. 
If the quantity is great, it may take days or weeks to melt ; and 
if snow continues falling, it goes on accumulating all over the 
surface of a country (which water cannot do), and may thus 
form such a mass that the warmth of the w*hoIe succeeding sum- 
mer may not be able to melt it. It then produces perpetual 
enow, such as we find above a certain altitude on all the great 
mountains of the globe ; and when this takes place cold is ren- 
dered permanent, no amount of sun heat warming the air or the 
earth much above the freezing-point. This is illustrated by the 
often-quoted fact that at 80° N. lat. Captain Scoresby had the 
pitch melted on one side of his ship by the heat of the sun, 
while water was freezing on the other side owing to the coldness 
of the air. 

The quantity of heat required to melt ice or snow is very 
great, as we all know by experience of the long time masses of 
snow will remain unmelted even in warm weather. We shall, 
however, be better able to appreciate the great eflfect this lias 
upon climate by a few figures showing what this amount really 
is. In order to melt one cubic foot of ice, as much heat is re- 
quired as would heat a cubic foot of water from the freezing- 
point to 176"^ F., or two cubic feet to 88"^ F. To melt a layer 
of ice a foot thick will therefore use up as much heat as would 
raise a layer of water two feet thick to the temperature of 88° 
F. ; and the effect becomes still more easily understood if we es- 
timate it as applied to air, for to melt a layer of ice only one and 
a half inch thick would require as much heat as would raise a 
stratum of air 800 feet thick from the freezing-point to the tropi- 
cal heat of 88° F. ! We thus obtain a good idea, both of the won- 
derful power of snow and ice in keeping down temperature, and 
also of the reason why it requires so long a time to melt away, 
and is able to go on accumulating to such an extent as to be- 
come permanent. These properties would, however, be of no 
avail if it were liquid, like water; hence it is the state of solid- 
ity and almost complete immobility of ice that enables it to pro- 
duce by its accumulation such extraordinary effects in physical 



ISLAND LIFE. 



[PillT J. 



geograpiiy and in fliinate as we seo in tlie glaciers of Switzer- 
land and the iue-capped iEitcrior of Ureonland. 

High Land and G^renl Moisture Easential to t/te Initiation of 
a Glacial Epoch. — Aiiotber point of great importance in con- 
nection witli tliis subject is the fact that this permanent storing- 
np of cold depends entirely on the annual ainonnt of snow-fall 
in proportion to that of the sun and air heat, and not on the act- 
ual cold of winter, or even on the average cold of the year. A 
place may be intensely cold in winter and tnay Imve a short 
arctic BUinnicr, yet, if so little snow falls that it is quickly melted 
by the returning sun, there is nothing to prevent the summer 
being hot and the earth producing a luxuriant vegetation. As 
an example of this we have great forests in tiie extreme North 
of Asia and America where the wintera are colder and the sum- 
mers shorter than in Greenland, in lat. 62° N., or tiian in ileai-d 
Island and South Georgia, both in lat. 63° S., in the Southern 
Ocean, and almost wholly covered with perpetual snow and ice. 
At the *' Jai'din" on the Mont Blanc range, above the line of 
perpetual snow, a thermometer in an exposed situation marked 
— 6° F. as the lowest winter temperature ; wJiile in many parts 
of Siberia mereury freezes several weeks in winter, showing a 
temperature below —40° F.; yet here the summers are hot, all 
the snow disappears, and there is a luxuriant vegetation. Even 
in the very highest latitudes reached by our last arctic exjiedi- 
tion there is very little perpetual snow or ice, for Captain Nai-es 
tells us that north of Hayes's Sound, in lat. 79° IS., the mountains 
were remarkably free from ice-cap, while extensive tracts of 
land were free from snow during summer, and covered with a 
rich vegetation with abundance of bright flowers. The reason 
of this is evidently the scanty snow-fall, which rendered it some- 
times difficult to obtain enough to form shelter-banks around 
the ships; and this was north of S0° N. lat,, wliere the sun 
was absent for a hundred and forty two days. 

Perpetual Snow nowhere Heists on Lowlands. — It is a very 
remarkable and most suggestive fact that nowhere in the world 
at the present time are there any cstcnsivo lowlands covered 
with perpetual snow. The Tundras of Siberia and the barren 
grounds of Nortli America are all clothed with some kind of 



Chap. VIII.] THE CAUSES OF GLACIAL EPOCHS. 129 

summer vegetation ; * and it is only where there are lofty moun- 
tains or plateaus — as in Greenland, Spitzbergen, and Grinnell's 
Land — that glaciers, accompanied by perpetual snow, cover the 
country, and descend in places to the level of the sea. In the 
antarctic regions there are extensive highlands and lofty moun- 
tains, and these are everywhere exposed to the influence of moist 
sea-air; and it is here, accordingly, that we find the nearest ap- 
proach to a true ice-cap covering the whole circumference of 
the antarctic continent, and forming a girdle of ice-cliffs which 
almost everywhere descend to the sea. Such antarctic islands as 
South Georgia, South Shetland, and Heard Island are often said 
to have perpetual snow at sea-level ; but they arc all very moun- 
tainous, and send down glaciers into the sea, and as they are 
exposed to moist sea-air on every side, the precipitation, almost 
all of which takes the form of snow even in summer, is of 
course unusually large. 

That high land in an area of great precipitation is the neces- 
sary condition of glaciation is well shown by the general state 
of the two polar areas at the present time. The northern part 
of the north temperate zone is almost all land, mostly low but 
with elevated borders ; while the polar area is, with the excep- 
tion of Greenland and a few other considerable islands, almost 
all water. In the Southern Hemisphere the temperate zone is 
almost all water, while the polar area is almost all land, or is at 
least enclosed by a ring of high and mountainous land. The 
result is that in the north the polar area is free from any ac- 
cumulation of permanent ice (except on the highlands of Green- 
land and Grinnell's Land), while in the south a complete barrier 
of ice of enormous thickness appears to surround the pole. Dr. 
CroU shows, from the measured height of numerous antarctic 



' In nil Account of Professor Nordenskjold's recent expedition round the nortiiern 
const of Asiji. given in Nature, November 20, 1879, we have the following passage 
fidly supporting the stnteroent in the text : ^' Along the whole coast, from the White 
Sea to Behring Strait, no glacier was seen. During autumn the Siberian coast is 
nearly free of ice and snow. There are no mountains covered all the year round 
with snow, although some of them rise to a height of mora than two thousand feet." 
It must be remembered thnt the north coast of Eastern Siberia is in the area of sup- 
posed greatest winter cold on the globe. 

9 



icebergs {often miles in ieiigtli) that the ice-sbect from which 
they are the hi-okeu outer Erngmcnts must be from a mile to a 
railo and a half in thickness.' As this is the thickness of the 
onter edge of the ice, it must he far thicker inland; and we 
thus find that the antarctic continent is at this very time suf- 
fering giaciation to quite as great an extent as we have i-caeon 
to believe oceurrcd in the same latitudes of the Noithern llcni- 
isjihcre during the last glacial epoch. 

The accompanying diagrams show the comparative state of 
the two polar areas both as regards the distribution of land and 
Boa, and the extent of the ice-sheet and floating icebergs. The 
nuidi greater quantity of ice at the south pole is nudoubteiily 
due to tlie presence of a large extent of high land, which acta 
«8 a condenser, and an unbroken eiirroundiug ocean, which af- 
fords a constant supply of vapor; and the effect is intensified 
by winter being there in aphelion, and thus several days longer 
than with us, wliile the whole Southern Hemisphere is at that 
time farther from the sun, niid tliei-efore receives less heat. 

We see, however, that with less favorable conditions for the 
production and accumulation of ice, Greenland is glaciated down 
to lat. 01°. Wliat, then, would be the effect if the antarctic 
continent, instead of being confined almost wholly within the 
south polar circle, were to extend in one or two great moun- 
tainous promontoriea far into the temperate zone? The com- 
paratively small Heard Island, in S. lat. 53°, is even now glaci- 
ated down to the sea. What would be its condition were it a 
northerly extension of a lofty antarctic continent? We may 
be quite sure that giaciation wonid then be far more severe, and 
that an ice-sheet corresponding to that of Greenland might ex- 
tend to beyond the parallel of 50' S. lat. Even this is probably 
too low an estimate, for on tbe west coast of New itealand, in S. 
lat. 43° 35', a ghieier even now descends to witiiin seven hundred 
and five feet of the sea-level; and if those islands were the 
northern extension of an niitaretic continent, we may be pretty 
sure that they would be nearly in the icc-covcred condition of 
Greenland, although situated in the hititiidc of Marseilles. 

' "On llie Glarial Epoch," by James Croll, Onlm/Kiil Mnijariai, Juir, Aiigiui, 



13S 



ISLAKD LIFU;. 



[Paw I. 



Vonditi-jns JJderminiiuj the Presence or Ahaence of PerpeUtal 
finoio. — It is clear, then, tliat the vicinity of a sea or ocean to 
supply moisture, together with high land to serve as a condenser 
of that nioistnre into snow, are the prime essentials of a great 
accninnhition of ice ; and it is fully in accordance with this view 
that wc find the most undouhtcd al^ua of extensive glaciation in 
the west of Eui-ope and the east of North Anieriea, both washed 
by thu Atlantic, and both having ahundancQ of high land to 
condense the nioistnre which it supplies, Witliout these condi- 
tions cold alone, however great, can prodnce no glacial epoch. 
This is strikingly shown by the fact that in the very coldest 
portions of the iwo northern continents — Eastern yiberia and 
the northwestern shores of Iliideon's Baj' — there in no peren- 
nial covering of snow or ice whatever. No less remarkable is 
the coincidence of the districts of greatest glaciation with those 
of greatest rainfall at the present time. Looking at a raiu-map 
of the British Isles, we see that the greatest area of excessive 
rainfall is the Highlands of Scotland, then follow the West of 
Ireland, Wales, and tlie North of England; and tiiese were gla- 
ciated pretty nearly in proportion to the area of country over 
which there is an abundant supply of moisture. So in Enrope, 
the Alps and the Scandinaviau mountains have excessive rain- 
fall, and have been areas of excessive glaciation, while the Ui-al 
and Caucasian mountains, with less rain, never seem to Jiave been 
proportionally glaciated. In North Anienca the eastern coast 
has an abundant rainfall, and New England with Kortheastern 
Canada seems to have been the source of much of the glaciation 
of that continent.' 

' '' Tlie genoml obMnce of recenl mniUx of gliii-inl action in l^siam I'iurotM ii ucll 
knnwn ; iinil ilia seriei of cliangis w1ii<:li linvo been lo neEl traced nnd dcscri1i«il by 
I'roftWHir Kinbii an occarring in iIiohi distritti M«nii lo leave no room for lliose pe- 
tiodicnl extension* of ' iee-cn)ni' will) wliicli louie nntliors in thin couniry lincc nmnsed 
tliemsclvu tind Ilic^ir rsntlera, Mr. Canijibell, wliusa alnlily lo nvognite llie phjsicut 
evidence ofglneien will Bcnrcely be qamtioiioil, lindii <|uiie ibe samo absence of tlie 
liraof of nieniive irc-nelinn in Nurtli Ainericn woilwnrd of ilie meridimi of Clii- 
I'dtEo" lI'i'DfvfMir J.W. Jiidd, in Utologieat U'lgatinr, 1676, p. 61)9). 

The uiDie author nuies the diminnlion of mnrlut of ice-action on gainic eoititnrd in 
■he Alp« ; and llie Altai Monnlnini fnr in Centml Aiia ihow no aigni of linviiig been 
largely glnciolcd. West of the Rocliy Mountnina, honever, in tlie tjierm Nevndn nnd 
the const rangci fiii'thernonh, lignit of cxlcniivc old glncieri ngnin nppenr; nil wliieh 



CiiAP.VlIl.] THE CAUSES OF GLACIAL EPOCHS. 133 

The reason why no accumulation of enow or ice ever takes 
place on arctic lowlands is explained by the observations of 
Lieutenant Payer of tlie Austrian Polar Expedition, who found 
that during the short arctic summer of the highest latitudes the 
ice-fields diminished four feet in thickness under the infiuence 
of the sun and wind. To replace this would require a precipi- 
tation of snow equivalent to about forty-five inches of rain, an 
amount which rarely occurs in lowlands out of the tropics. In 
Siberia, within and near the Arctic Circle, about six feet of snow 
covers the country all the winter and spring, and is not sensibly 
diminished by the powerful sun so long as northerly winds keep 
the air below the freezing-point and occasional snow-storms oc- 
cur. But early in June the wind usually changes to southerly, 
probably the southwestern anti-trades overcoming the north- 
ern inflow ; and under its influence the snow all disappears in a 
few days, and the vegetable kingdom bursts into full luxuriance. 
This is very important as showing the impotence of mere sun 
heat to get rid of a thick mass of snow so long as the air re- 
mains cold, while currents of warm air are in the highest degree 
effective. If, Iiowever, they are not of suflBciently high tem- 
perature, or do not last long enough to melt the snow, they are 
likely to increase it from the quantity of moisture they bring 
with them, which will be condensed into snow by coming into 
contact with the frozen surface. We may therefore expect the 
transition from perpetual snow to a luxuriant arctic vegetation 
to be very abrupt, depending as it must on a few degrees more 
or less in the summer temperature of the air; and this is quite 
in accordance with the fact of corn ripening by the sides of Al- 
pine glaciers. 

tJjjicieixcy of Astronomical Causes in Produ<:ing Glaciation. — 
Having now collected a suflicient body of facts, let us endeavor 
to ascertain what would be the state to which the Northern 
IIemisi)here would be reduced by a high degree of eccentricity 
and a winter in aphelion. When the glacial epoch is supposed 
to have been at its maximum, about 210,000 years ago, the cc- 

phenomena are strikingly in accordfince with the theory here advocated of the abso- 
hue dejMindence of glaciation on abundant rainfall and elevated snow condensers and 
accnmuhitors. 



ISU?fD LIFE. 



[pABTt 



ceiitricity was more than three times as gi'cat as it is now ; and, 
according to Dr. Croll's calculations, tliu midwinter temperature 
of the Northern Hemisphere would have been lowered 36" F., 
wliiie the winter Iiulf of the year would have been twenty-six 
days longer than the Bumnier half. This would bring the Jan- 
uary mean tcmiiei-atiire of England and Scotland almost down 
to zero, or about 30° F, of frost, a winter climate correspond- 
ing to that of Labrador, or the coast of Greenland on the Arctic 
Circle. But we niust remember that tlie summer would be just 
as much hotter than it is now, and tlio problem to be solved is, 
whether the snow that fell in winter would accumulate to such 
an extent that it ■would not be melted in summer, and so go on 
increasing year by year till it covered the whole of Scotland, Ire- 
land, and Wales, and much of England. Dr.Crall and Dr. Geikic 
answer without hesitation that it would. Sir Charles Lyell main- 
tained that it would only do so when geographical conditions 
were favorable; while the late Mr. Belt has argued that eccen- 
tricity alone would not produce the effect unless aided by in- 
creased obliquity of the ecliptic, which, by extending the width 
of the polar regions, would increase the duration and severity of 
the winter to such an extent that snow and ice would be formed 
in the arctic and autai-ctic regions at the same time, whether 
the winter were in perihelion or aphelion. 

The problem we have now to solve is a very difficult one, be- 
cause we have no case at all parallel to it from wliicli we can 
draw direct ooncluaiona. It is, however, clear, from the various 
considerations wo have already adduced, that the increased cold 
of winter, when the eccentricity was great and tlie sun in aphe- 
lion during ttiat season, would not of itself produce a glacial 
epoch unless the amount of vapor supplied for condensation was 
also exceptionally great. The greatest quantity of snow falls in 
the arctic regions in summer and autumn, and with us the great- 
est quantity of rain falls in the antunmal months. It seems 
probable, then, that in all northern lands glaciation would com- 
mence when autumn occuned in aphelion. All the rain which 
falls on our mountains at that season would then fall as snow, 
and, being further increased by the snow of winter, would form 
accumulations which the summer might not be iible to melt. 



Chap. VIII.] THE CAUSES OF GLACIAL EPOCHS. 135 

As time went on, and the aphelion occurred in winter, the per- 
ennial snow on the mountains would have accumulated to such 
an extent as to chill the spring and summer vapors, so that tliey 
too would fall as snow, and thus increase the amount of deposi- 
tion; but it is probable that tin's would never in our latitude 
have been sufficient to produce glaciation, were it not for a se- 
ries of climatal reactions which tend still further to increase the 
production of snow. 

Action of Meteorological Causes w Intensifying Glaciation, — 
The trade-winds owe their existence to the great difference be- 
tween the temperature of the equator and that of the poles, which 
causes a constant flow of air towards the equator. The strength 
of this flow depends on the diflference of temperature and the ex- 
tent of the cooled and heated masses of air, and this effect is now 
greatest between the south pole and the equator, owing to the 
much greater accumulation of ice in the antarctic regions. The 
consequence is that the southeast trades are stronger than the 
northeast, the neutral zone or belt of calms between them not 
being on the equator, but several degrees to the north of it. But 
just in proportion to the strength of the trade -winds is the 
strength of the anti - trades, that is, the upper return current 
wliich carries the warm moisture-laden air of the tropics towards 
the poles, descending in the temperate zone as west and south- 
west winds. These are now strongest in the Southern Hemi- 
sphere, and, passing everywhere over a wide ocean, they supply 
the moisture necessary to produce the enormous quantity of 
snow which falls in the antarctic area. During the period we 
are now discussing, however, this state of things would have 
been partially reversed. The south polar area, having its winter 
in perihelion, would probably have had less ice, while the north 
temperate and arctic regions would have been largely ice-clad ; 
and the northeast trades would therefore be stronger than they 
are now. The southwesterly anti-trades would also be stronger 
in the same proportion, and would bring with them a greatly in- 
creased quantity of moisture, which is the prime necessity to 
produce a condition of glaciation. 

But this is only one half of the effect that would be produced, 
for the increased force of the trades sets up another action which 



136 ISLAND LIFE. [I'Anr I. 

still further helps on tlic aecnniulation of snow and ice. It is 
now generally admitted tliat wo owe nmcli of our mild climate 
and our comparative freedom fi-oiii snow to tlie iuflneuce of the 
Gnlf Stream, which also ameliorates the climate of Scandinavia 
and Spitsbergen, as shown by the reiiiavkable northward cnrva- 
tnro of the iaotherniid lines, so that Drontheim, in N, lat. 62", has 
the aamo mean temperature as Halifax (Nova Scotia), in N. lat. 
45°. The quantity of heat now brought info the North Atlantic 
by the Gulf Stream dei>ends mainly on the superior strength of 
the southeast trades. When the northeast trades were the more 
powerful, the Gnlf Strcaui would certainly be of mucli less mag- 
nitude and velocity ; while it is possible, as Dr. CroU thinks, that 
a large portion of it might be diverted aouthward, owing to the 
peculiar form of the east coast of South America, and so go to 
Bwcli the Brazilian current and ameliorate the climate of the 
Southern Hemisphere, 

That effects of this nature would follow fram any increase of 
the arctic and decrease of the Antarctic ice may he considered 
certain ; and Dr. Crotl has clearly shown that in this case cause 
and effect act and react on eaclt other in a remarkable way. 
The increase of snow and ice in the Northern Hemisphere is the 
cause of an increased supply of moisture being brought by the 
more powerful anti-trades; and this greater supply of moisture 
leads to an extension of the ice, which reacts in still further 
increasing tlie supply of moisture. The same increase of snow 
and ice, by causing the northeast to be stronger than tiie south- 
east trade-winds, diminishes the force of the Gulf Stream, and 
this diminution lowers tiic temperature of the North Atlantic 
both in summer and winter, and thus helps on still further the 
formation and perpetuation of the icy mantle. It must also be 
remembered that these agencies are at the same time acting in 
a reverse way in the Southern Hemisphere, diminishing the sup- 
ply of the moisture carried by the anti-trades, and increasing 
the tempcralure by means of uiorc powerful southward ocean 
currents; and all this again reacts on the Northern Hemisphere, 
increasing yet further the supply of moisture by the more pow- 
erful aonthwcsterly winds, while still further lowering the tem- 
perature by ttie eoutitward diversion of the Gulf Stream. 



Chap. VIII.] THE CAUSES OF GLACIAL EPOCHS. 137 

Summary of Principal Causes of Glaciation. — I have now 
suflSciently answered the question why the short hot summer 
would not melt the snow which accumulated during the long 
cold winter. (produced by high eccentricity and winter in aphe- 
lion), althougli the annual amount of heat received from tlie 
sun was exactly the same as it is now, and equal in the two 
hemispheres. It may be well, before going further, briefly to 
summarize the essential causes of this apparent paradox. These 
are — primarily, the fact that solar heat cannot be stored up, ow- 
ing to its being continually carried away by air and water, while 
cold can be so stored up, owing to the comparative immobility 
of snow and ice ; and, in the second place, because the two great 
heat-distributing agencies, the winds and the ocean currents, are 
so affected by an increase of the snow and ice towards one pole 
and its diminution towards the other as to help on the process 
when it has once begun, and by their action and reaction pro- 
duce a maximum of effect which, without tlieir aid, would be 
altogether unattainable. 

But even tliis does not exhaust the causes at work all tending 
in one direction. Snow and ice reflect heat to a much greater 
degree than does land or water. The heat, therefore, of the short 
summer would have far less effect than is due fo its calculated 
amount in melting the snow, because so much of it would be 
lost by reflection. A portion of the reflected heat would, no 
doubt, warm the vapor in the atmosphere ; but this heat would 
l>e carried off to other parts of the eartli, while a considerable 
portion of tlie whole would be lost in space. It must also be 
remembered tliat an enormous quantity of heat is used up in 
melting snow and ice, without raising its temperature; each 
cubic foot of ice requiring as much heat to melt it as would 
raise nearly six cubic feet of water 30° F. It has, however, been 
argued that because when water is frozen it evolves just as much 
heat as it requires to melt it again, there is no loss of heat on 
the whole ; and, as this is adduced as a valid argument over and 
over again in every criticism of Dr. Croll's theory, it may be 
well to consider it a little more closely. In the act of freezing, 
no doubt, water gives up some of its heat to the surrounding 
air; but that air still remains below the freezing-pointy or freez- 



[Pai 

iDg would not take place. The lieat libeiatcil by freezing is, 
til cref ore, what may be termed low-grade heat — Iieat incapable 
of melting snow or ice; while the bent absorbed while ice or 
SHOW is melting is high-grade beat, such rb Is capable of melt- 
ing snow and supporting vegetable growth. Moreover, the low- 
grade heat liberated in the formation of snow is usually libei- 
atod high up in the atmosphero, wbei-c it may be carrietl off by 
winds to more southern latitudes; while the beat absorbed in 
molting the surface of snow and ice is absorbed close to the 
earth, and is thus prevented from warming the lower atmosphere, 
which is in contact with vegetation. The two phenomena, tbei-e- 
fore, by no means counterbalauce or counteract each other, as it 
is so constantly and superficially asserted that thoy do. 

Effect ofClouda aiul Fog in Cutting off the iSuiCs Heat. — An- 
other very important cause of diminution of heat during sum- 
mer in a glaciated country would be the intervention of clonds 
and fogs, wliieli would reflect or absorb a large proportion of 
the sun heat and prevent it reaching the surface of the earth; 
and such a cloudy atmosphere would be a necessary result of 
large areas of high land covered with snow and ice. That such 
a prevalence of fogs and cloud is an actual fact in all ice-clnd 
countries hns been shown by Dp. Groll most conclusively, and 
he has further shown that the existence of perpetual snow often 
depends upon it. South Georgia, in the latitude of Yorkshire, 
is alnioBt, and Sandwich Land, in the latitude of the North of 
Scotland, is entirely, covered with perpetual snow; yet in their 
eummer the sun is three million miles nearer the earth than it 
is in our summer, and the heat actually received from tbu sun 
must bo sufficient to raise the temperature 20° F. higher than 
in the same latitudes in the Northern Jlemispliere, were the 
conditions equal^nstead of which their summer temperature is 
probably fully 20° lower. The chief cause of this can only bo 
that the heat of the sun does not reach the surface of the earth ; 
and that this is the fact is teetifled by all antarctic voyagers. 
Danvin notes the cloudy sky and constant moisture of the soutli- 
eni part of Chili, and in his remarks on the climate and pro- 
ductions of the antaretic islands he says, "In the Southern 
Ocean the winter is not so excessively euld, but the summer is 



CuAP.VIIL] THE CAUSES OF GLACIAL EPOCHS. 139 

far less hot (than in the north), for the clouded sky seldom allows 
the sun to wa)*vi the ocean, itself a bad absorbent of heat ; and 
lience the main temperature of the year, which regulates the 
zone of perpetually congealed under-soil, is low." Sir James 
Ross, Lieutenant Wilkes, and other antarctic voyagei*s speak of 
the snow-storms, the absence of sunshine, and the freezing tem- 
perature in the height of summer; and Dr. CroU shows that 
this is a constant phenomenon accompanying the presence of 
large masses of ice in every part of the world.* 

In reply to the objections of a recent critic. Dr. Croll has 
given a new proof of this important fact by comparing the 
known amount of snow-fall with the equally well-known melt- 
ing power of direct sun heat in diflferent latitudes. He says, 
" The annual precipitation on Greenland in the form of snow 
and rain, according to Dr. Kink, amounts to only twelve inches, 
and two inches of this he considers is never melted, but is car- 
ried away in tlie form of icebergs. The quantity of heat re- 
ceived at the equator from sunrise to sunset, if none were cut 
oflf by the atmosphere, would melt three and a third inches of 
ice, or a hundred feet in a year. The quantity received between 
latitude 60° and 80°, which is that of Greenland, is, according to 
Meech, one half that received at the equator. The heat received 
by Greenland from the sun, if none were cut oflf by the atmos- 
phere, would therefore melt fifty feet of ice per annum, or fifty 
times the amount of snow which falls on that continent. What, 
then, cuts oflE the ninety-eight per cent, of the sun's heat ?" The 
only possible answer is that it is the clouds and fog during a great 
part of the summer, and reflection from the surface of the snow 
and ice when these are absent. 

South Temperate America as Illustrating the Influence of 
Astrojiomi^^al Causes on Climate, — Those persons who still doubt 
the effect of winter in aphelion with a high degree of eccentric- 
ity in producing glaciation should consider how the condition 
of south temperate America at the present day is explicable if 



^ For numerous details and illustrations, see the paper *'0n Ocean Currents in 
Relation to the Physical Theory of Secular Changes of Climate,*' in the Philosophical 
Magazine y 1870. 



ISLAND LIFE. 



[Paui I. 



tliey reject this agency. The line of perpetual snow in the 
Southern Andes is so low as 6O00 feet in the same latitude as 
tlie Pyrenees. In the latitude of the Swiss Alps, mountains only 
6200 feet high [iroduco immense glaciers which descend to the 
sea-Ievel ; wliile, in the latitude of Cumberland, mountains only 
from 31)00 to iOOO feet hiyli have every valley filled with streams 
of ice descending to the sea-coast and giving off abundance of 
huge icebergs.' Here we have exactly the condition of things 
to which England and Western Europe were subjected during 
the latter portion of tlie glacial epoch, when every valley in 
Wales, Cumberland, and Scotland liad its glacier; and to what 
can this state of things be imputed if not to the fact that there 
is now a moderate amount of eccentricity, and the winter of the 
Southern Hemisphere is in aphelion? The mere geographical 
position of the southern extremity of America does not seem 
especially favorable to the production of such a state of glacia- 
tion. The land narrows from the tropics southward, and ter- 
minates altogether in about the latitude of Edinburgh; ttie 
nionutaiuB are of moderate heiglit; while during summer the 
fiitn is three millions of miles nearer, and tlie heat received from 
it is equivalent to a rise of 20° F. as compai'ed with the same 
season in the Northern Hemisphere. Tlie only important dif- 
ferences are the open Southern Ocean, the longer and colder 
winter, and the general low tempeniture caused by the south 
polar ice. But the great accumulation of south polar ice is it- 
self due to the great e.xtent of high land within tlio Antarctic 
Circle acted upon by the long cold winter and furnislied with 
moisture hy the surrounding wide ocean. These conditions of 
high knd and open ocean we know did not prevail to so great 
ail extent in the Northern Hemisphere during the glacial 
epoch as they do in the Southern Hemisphere at the present 
time ; but tlie other acting cause — the long cold winter — existed 
in a far higher degree, owing to the eccentricity being about 
three times as much as it is now. It is, so far as we know or 
are justified in believing, the only efficient cause of glaciation 
which was undoubtedly much more powerful at that time; and 



mi. ilioWorlJ,"2d ed..ii[.. aH-2.11. 



chap.vhi.] the causes of glacial epochs. 141 

we are tliereforc compelled to accept it as the most probable 
cause of the much greater glaciation which then prevailed. 

Geographical ChangetSy how far a Cause of Glaciation, — 
Messre. Croll and Geikie have both objected to the views of Sir 
Charles Lyell as to the preponderating influence of the distribu- 
tion of land and sea on climate ; and they maintain that if the 
land were accumulated almost wholly in the equatorial regions, 
the temperature of the earth's surface as a whole would be low- 
ered, not raised, as Sir Charles Lyell maintained. The reason 
given is that the land being heated heats the air, which rises and 
thus gives off much of the heat to space, while the same area 
covered with water would retain more of the heat, and by means 
of currents carry it to other parts of the earth's surface. But 
although the mean temperature of the whole earth might be 
somewhat lowered by such a disposition of the land, there can 
be little doubt that it would render all extremes of temperature 
impossible, and that even during a period of high eccentricity 
there would be no glacial epochs, and perhaps no such thing as 
ice anywhere produced. This would result from there being no 
land near the poles to retain snow, while the constant inter- 
change of water by means of currents between the polar and 
tropical regions would most likely prevent ice from ever form- 
ing in the sea. On the other hand, were all the land accumulated 
in the polar and temperate regions, there can be little doubt that 
a state of almost i:>erpetual glaciation of much of the land would 
result, notwithstanding that the whole earth should theoretically 
be at a somewhat higher temperature. Two main causes would 
bring about this glaciation. A very large area of elevated land 
in high latitudes would act as a powerful 'condenser of the enor- 
mous quantity of vapor produced by the whole of the equatorial 
and much of the temperate regions being areas of evaporation, 
and thus a greater accumulation of snow and ice would take 
place around both poles than would be possible under any other 
conditions. In the second place, there would be little or no check 
to this accumulation of ice, because, owing to the quantity of 
land around the polar areas, warm oceanic currents could not 
reach them, while the warm winds would necessarily bring so 
much moisture that they would help on instead of checking the 



149 



ISLAND I.IF£. 



[Hab 



process of ice-accnmnlation. If we suppose the continents to be 
of the same total area and to Imve tlie same extent and altitudo 
of moiintain-ranges ns the present ones, these mountains must 
necessarily offer an almost contiwnous barrier to the vapor-hear- 
ing -winds from the south, and the result would probably be that 
three fourths of tlie laud would bo in the ice-clad condition of 
Greenland, while a comparatively narrow belt of the more 
Bouthcro lowlands would alone afford habitable surfaces or pro- 
duce any woody vegetation, 

Notwithstanding, therefore, the criticism above referred to, I 
believe that Sir Charles Lyell was substantially right, and that 
the two ideal maps given in the " Principles of Geology " (lltli 
ed., Vol. I-, p. 270), if somewhat modified so as to allow a freer 
passage of currents in the tropics, do really exhibit a condition 
of the earth which by geographical changes alone would bring 
about a perpetual summer or a» almost nnivei'sal winter. JJnl 
we have seen in our sixth chapter that there is the strongest cu- 
mulative evidence, almost amounting to demonstration, that for 
all known geological periods our continents and oceans have oc- 
cupied the same general position they do now, and tliat no such 
radical changes in tlie distribution of sea and land as imagined, 
by way of hypothesis, by Sir Charles Lyell have ever occurred. 
Such an hypothesis, however, is not without its use in our pres- 
ent inquiry ; for if we obtain thereby a clear conception of the 
influence of such great changes on climate, wo are the better 
able to appreciate the tendency of lesser changes, such as have 
undoubtedly often occurred. 

Land at a linrrirfT to Ocean Curren,t8. — Wo have seen al- 
i-ctidy tlie great importance of elevated land to serve us condens- 
ers aTid ice-aecumulators; but there is another and hardly less 
important effect that may be produced hy an extension of land 
in high latitudes, wliJeh is, to act as a barrier to the fiow of ocean 
currents. In the region with which wo aro more immediately 
interesteil it is easy to sec how a comj>aratively slight alteration 
of land and sen, such as has undoubtedly occurred, would pro- 
duce an enormous effect on climate. Lot us suppose, for in- 
6tHncc, that tho British Isles again became continental, and that 
this continental land extended across tlie Faroe Islands and Ice- 



CuAP.VIIL] THE CAUSES OF GLACIAL EPOCHS. 143 

land to Greenland. The whole of the warm waters of the Atlan- 
tic, with the Gulf Stream, would then be shut out from North- 
ern Europe, and the result would almost certainly be that snow 
would accumulate on the high mountains of Scandinavia till they 
became glaciated to as great an extent as Greenland, and the 
cold thus produced would react on our own country and cover 
the Grampians with perpetual snow, like mountains of the same 
hcisrht at even a lower latitude in South America. 

If a similar change were to occur on the opposite side of the 
Atlantic, very different effects would be produced. Suppose, for 
instance, the east side of Greenland were to sink considerably, 
while on the west the sea-bottom were to rise in Davis's Strait 
so as to unite Greenland with BaflSn's Land, thus stopping alto- 
gether the cold arctic current with its enormous stream of ice- 
bergs from the west coast of Greenland. Such a change might 
cause a great accumulation of ice in the higher polar latitudes, 
but it would certainly produce a wonderful ameliorating effect 
on the climate of the east coast of North America, and might 
raise the temperature of Labrador to that of Scotland. Now 
these two changes have almost certainly occurred, either togeth- 
er or separately, during the Tertiary period, and they must have 
had a considerable effect either in aiding or checking the terres- 
trial and astronomical causes affecting climate which were then 
in operation. 

It would be easy to suggest other probable changes which 
would produce a marked effect on climate ; but we will only re- 
fer to the subsidence of the Isthmus of Panama, which has cer- 
tainly happened more than once in Tertiary times. If this sub- 
sidence were considerable, it would have allowed much of the 
accumulated warm water which initiates the Gulf Stream to 
pass into the Pacific; and if this occurred while astronomical 
causes were tending to bring about a cold period in the North- 
ern liemisphere, the resulting glaciation might be exceptionally 
severe. The effect of this change would, however, be neutralized 
if at the same epoch the Lesser and Greater Antilles formed a 
connected land. 

Now, as such possible and even probable geographical changes 
are very numerous, they must have produced important effects ; 



lU 



ISLAND LIFE. 



[PawtL 



and tliougli wc nmy ndmit tliat tlm astronomical causes already 
explained were the most important in determining tlie last gla- 
cial epocli, vc must also allow that geographical changes must 
often have Jiad an equally important and perhaps even a pre- 
ponderating infinence on climate. We mnst also remember that 
changes of land and sea are ahnost always accompanied by c!e- 
ration or depression of the pre-existing land ; and ivhereaa the 
former prodnees its chief effect by diverting tlio conrse of warm 
or cold oceanic currents, the latter is of not less impoi'tanco in 
adding to or diminishing those areas of condensation and Ice-ac- 
cumulation whicli, as we havo eeeu, are the most efficient agents 
in producing glaciation. 

If, then, Sir Charles Lyeil may have somewhat erred in attach- 
ing too exclusive an importance to geograpliical clianges as 
bringing abont mutations of climate, his critics have, I think, 
attached far too little importance to these clianges. We know 
that they liavo always been in progress to a sufficient extent to 
produce important climatal eifecCs; and we shall probably be 
nctti'cst the truth if wo consider that great extremes of cold have 
only occurred when astronomical and geographical causes were 
acting in the same direction, and thus produced n cunmlative 
result ; while, through the agency of warm oceanic currents, the 
latter alone have been the chief cause of mild climates in high 
latitudes, as we shall prove in onr next chapter.' 



' Tli« influence of gengrnpliicn] changes on climate is nov! held liy tnnnf geologijts 
II lio oppose what tiiey consiitcr tlie extrnvagnni hypotlieses of 1>1'. Croli. Tims, Pro- 
finwor Dnna impnica tlie glacinl epoch cliiefl)', if not wtiollv, to elcvniion of the Und 
uiuseil l>j ihc Iniernl pcesniire due to ■hrinkitiK of (lie eorili'ii crust il>ai lins caused all 
uthcr elevations and depre^Bions. He tayn, "Noiv that elcvaiion of tlie land over 
(lie higher lntitutle« which hroaglit on the glacial ent is A nntural result of ilio tame 
Bgenry, nnd n tiatnral and nlrnoai neceuary cnunierpart of iho coml-ialand tutwid- 
eiice wliii:li rnoBi have been then in proKrets. The accumulating, Tutding, sotidifica- 
tion, nnd crystnli'iBiiioa orrocbe titlendin); all the rock-mxlung and mounmin-making 
through ihc I'alioainic, Memioic, and Conoznic orni had grenlly siilTened the cmsl 
in these parta ; nnd hence, in nfteMimcn, the conlinentnl movements reiutiing frant 
llie lateml picsiure necessnrily nppenrcd over the more nanhem poviintis ot the eon- 
Tinenc, where ilie Bccutnulaiiuns end oilier chnnecs hnd been rolallvely «mnll. Tu 
the siihsidcnce whii-li followed the cUvnlion, the weight of ihn ira-cnp mny hnve con- 
iribnted in some small dogroe. Itui llio grent ludnncing movcmeuu of the crust of 
Iho cunlinemnl nnd oconnic nrus lliun going fonrnrd must hnvp hnd n gtenllr pre- 



Chap. VIII.] THE CAUSES OF GLACIAL EPOCHS. 145 

On the Theory of Interglacial Periods and their Probable 
C/iaracter. — The theory by which the glacial epoch is here ex- 
plained is one which apparently necessitates repeated changes 
from glacial to warm periods, with all the consequences and 
modifications both of climate and physical geography which fol- 
low or accompany such changes. It is essentially a theory of al- 
ternation ; and it is certainly remarkable in how many cases ge- 
ologists have independently deduced some alternations of cli- 
mate as probable. Such are the interglacial deposits indicating 
a mild climate, both in Europe and America ; an early phase of 
very severe glaciation when the "till" was deposited, with later 
less extensive glaciation when moraines were left in the valleys; 
several successive periods of submergence and elevation, the 
later ones becoming less and less in amount, as indicated by the 
raised beaches slightly elevated above our present coast -line; 
and, lastly, the occurrence in the same deposits of animal remains 
indicating both a warm and a cold climate, and especially the 
existence of the hippopotamus in Yorkshire soon after the peri- 
od of extreme glaciation. 

But although the evidence of some alternations of climate 
seems indisputable, and no suggestion of any adequate cause for 
them other than the alternating phases of precession during high 
eccentricity has been made, it by no means follows that these 
changes were always very great — that is to say, that the ice 
completely disappeared and a warm climate prevailed through- 
out the whole year. It is quite evident that during the height 
of the glacial epoch there was a combination of causes at work 
which led to a largo portion of Northwestern Europe and East- 
ern America being buried in ice to a greater extent even than 

ponderating effect in the oscillating agency of all time — lateral pressare within the 
crust.'* — American Jnurnal of Science and Arttt^ 3d Series, Vol. IX., p. 318. 

In the second edition of his '^Manual of Geology," Professor Dana suggests eleva- 
tion of aiTtic hinds sufficient to exclude the Gulf Stream as a source of cold during 
glacial epochs. This, he thinks, would have made an e{K>ch of cold at any era of the 
globe. A deep submergence of Behring Strait, letting in the Pacific warm current 
to the polar area, would have produced a mild arctic climate like that of the Miocene 
))eriod. When the warm current was shut out from the polar area, it would yet reach 
near to it, and bring \\\\\\ it that abundant moisture necessary for glaciation. — 
l*p. i>4 1 , 75."), 7.'»C. 

10 



146 



ISLAND UFE. 



[PiW I. 



Greenland is now, since it certainly extended beyond the land 
and filled up all the shallow seas between our islands and St-an- 
dinavia. Among these causes we must reckon a diminntion of 
the force of tlio Gulf Stream, or its being diverted from the 
northwestern coasts of Europe; and what we have to consider 
is, whether the alteration fi-om a long cold winter and short hot 
summer to a short mild winter and long cool snmnier would 
greatly affect the amount of ice if the ocean currents remaineii 
(he game. The force of these currents are, it is true, by onr hy- 
pothesis, modified by the increase or diminntion of the ice in the 
two hemispheres alternately, and they then react npon climate ; 
but they cannot be tlms changed till after the ice-accumniation 
has been considerably affected by other causes. Tlieir direction 
may indeed be greatly cJianged by slight alterations in the out- 
line of the land, wliile tliey may be barred out altogether by 
otlier alterations of not very great amount ; but such changes as 
these have no relation to the ulteration of climates caused by the 
changing phases of precession. 

Now tiie existence at the present time of an ice-clad Green- 
land is an anomaly in the Northern Hemisphere only to be ex- 
plained by the fact tliat cold currents from the jiolar area flow 
down both sides of it. In Eastern Asia wo have the lofty Sta- 
iiovoi Mountains in the same latitude as the southern part of 
Greenland, which, though their summits are covered with per- 
petual snow, give rise to no ice-slioct, and, apiiarcntly, even to 
no important glaciers — a fact undoubtedly connected with the 
warm Japan current flowing partially into the Sea of Ochotsk. 
So in Northwest America we have the lofty coast range culmi- 
nating in Mt, St. Elias, nearly 15,000 feet high, and an extensive 
tract of high land to tlio north and northwest, with glaciers 
comparable in liize with those of New Zealand, although situated 
in latitude 60" instead of in latitude 45°. Hero, too, wo have tlie 
main body of the Japan current turning east and south, and 
thus producing a mild climate, little inferior to that of Norway, 
warmed by the Gulf Stream. We thus have it made clear that 
could the two arctic currents be diverted from Greenland, that 
country would become free from ice, and might even bo com- 
pletely forest-clad and inhabitable; while if tlie Japan current 



Chap. VIII. ] THE CAUSES OF GLACIAL EPOCHS, 147 

were to be diverted from the coast of Nortli America and a cold 
current come out of Behring Strait, the entire northwestern ex- 
tremity of America would even now become buried in ice. 

Now it is the opinion of the best American geologists that 
during the height of the glacial epoch Northeastern America 
was considerably elevated.* This elevation would bring the wide 
area of the banks of Newfoundland far above water, causing the 
American coast to stretch out in an immense curve to a point 
more than GOO miles east of Halifax ; and this would certainly 
divert nmch of the greatly reduced Gulf Stream straight across 
to the coast of Spain. The consequence of such a state of things 
would probably be that the southward-flowing arctic currents 
would be much reduced in velocity ; and the enormous quantity 
of icebergs continually produced by the ice-sheets of all the lands 
bordering the North Atlantic would hang about their shores and 
the adjacent seas, filling them with a dense ice-pack far surpass-, 
ing that of the antarctic regions, and chilling the atmosphere 
so as to produce constant clouds and fog with almost perpetual 
snow-storms, even at midsummer, such as now prevail in the 
worst portions of the Southern Ocean. 

But when such was the state of the North Atlantic (and, how- 
ever caused, such mvst htivo been its state during the height of 
tlie glacial epoch), can we suppose that the mere change from 
the distant sun in winter and near sun in summer to the reverse 
could bring about any important alteration — the physical and 
(jeographical causes of glaciation remaining unchanged f For, 
certainly, the less powerful sun of summer, even though lasting 
somewhat longer, could not do more than the much more pow- 
erful sun did during the phase of summer in perihelion, while 
during the less severe winters the sun would have far less power 
than when it was equally near and at a very much gi'cater alti- 
tude in summer. It seems to me, therefore, quite certain that 
whenever extreme glaciation has been brought about by high ec- 
centricity combined with favorable geographical and physical 
causes (and without this combination it is doubtful whether ex- 
treme glaciation would ever occur), then the ice-sheet will not be 

» DnnAs '* Manual of Geology," 2d cd., p. r>40. 



ISLAND LIFE. 



[P*. 



removed during the alternate phases of precession so long as 
these geographical nnd phy&iciil causes remaiu unaltered. It is 
true tint tlic warm ami cold oceanic currents, which aro the 
most important agentd in increasing or dimiQishiDg glaciation, 
depend for tlieir strength and efficiency upon the coinpamtivo 
extents of the northern and southern ice-sheets; but these ice- 
slieets cannot, I believe, increase or diminish to any important 
extent unless some geographical or physical change first occurs.' 

If this argument is valid, then it would follow that, so long as 
eccentricity was high, whatever condition of cliiuate was brought 
about by it in combination with geographical canses would per- 
sist through several phases of }treeession; but this wonld not 
neeesearily be the case when the eccentricity itself changed and 
became more moderate. It would then depend upon the pro- 
portionato effect of climatal and geographical causes in produc- 
ing glaciation as to what change would be produced by the 
changing pliasos of procession ; and we can best examine thiit 
question by considering the probable effect of the change in 
precession during the next period of 10,500 years, with the 
present moderate degree of eccentricity. 

Prohabh J^fct of Winler in Aphelion on the Climate of 
Britain.. — ^Let ua tlien suppose the wintera of the Northern 



' In reply (o nn olijeciion of a some'vlint limilnr iintara to lliis, Dr- Croll bns m- 
ceiill^ tinted (titafai/icai Magazinr, Ociober, 18711) llint lio " lias not ntBiimcd ttinl 
the con pnrat lire diiinppcnmura of tlio lea nn llic wnrm hcminphfra iliitiiig ilie pedod 
of high cccenlHcitf U due to imy ndcliiioiinl licut tierired Uora tlic sun in vunsequenm 
of (ho GTcntcr length of llie summer,'' but thnt "the i-onl nnd cITeciive cniiso of the 
diuifJiwnritnce ofihe Iceivoi tlio enormous irnniferrenceotcquotoriiilhcnt to lempor- 
nte and polnr legioni b; ntckna oforcun ctirrenl*." But this it iureir iirRiiingin n 
circle ; far the ocexn currenti nra miiinl/ due lo the difference nf teinperninrs of ilie 
poUir and cqnntoriol «r«ni coTnhinod will) tlic )>eciirtar form and position of ilie conii- 
nenis, nnil aunie ono or mni'e of thCH fiiclnrs nii»t be nlici'cd tr/Lr^ the ocsun cur- 
renu tawnid* ilie north polo (nn be incrDnret), Tlie only fnctor avnilnblo is the anl- 
nrciic ica ; nnd if this were largely increased, the northiTnid-Sawing currciiia might be 
to increased as lo cddU some of the nrciic ice, Bnt ihe very same argampnl applies 
to both poles. Without some gcogrnphicnl chnngo the nnlnrclic ice could not mn- 
terlnlly diminiali during in winter in iicrtlielinn, nor increase to nny importnnt uxlcnt 
dnrinfC the n])pa»ite phase. We iherefui'e twm lo huie no ovailnhle agency by which 
lo gelrii] of I he ice over ■ giscjnied conntry so lanij at the ffmgivphiail conJitloiit r«- 
maineJ «Hf lianyrd nnd llie (trtntririly cimlinual kl'jh. 



Chap.VIII.] the causes OF GLACIAL ErOCIIS. 149 

Hemisphere to become longer and much colder, the summers be- 
ing proportionately shorter and liotter, without any other change 
whatever. The long cold winter would certainly bring down 
the snow-line considerably, covering large areas of high land 
with snow during the winter months, and extending all glaciere 
and ice-fields. This would chill the superincumbent atmosphere 
to such an extent that the warm sun and winds of spring and 
early summer would bring clouds and fog, so that the sun heat 
would be cut off and much vapor be condensed as snow. The 
greater sun heat of summer would, no doubt, considerably reduce 
the snow and ice ; but it is, I think, quite certain that the extra 
accumulation would not be all melted, and that therefore the 
snow-line would be permanently lowered. This would be a nec- 
essary result, because the greater part of the increased cold of 
winter would be stored up in snow and ice, while the increased 
heat of summer could not be in any way stored up, but would 
be largely prevented from producing any effect, by reflection 
from the surface of the snow, and by the intervention of clouds 
and fog which would carry much of the heat they received to 
other regions. It follows that 10,000 years hence, when our win- 
ter occurs in aphelion (instead of, as now, in perihelion), there 
will be produced a colder climate, independently of any change 
of land and sea, of heights of mountains, or the force of currents. 
But if this is true, then the reverse change, bringing the sun 
back into exactly the same position with regard to us as it is in 
now (all geographical and physical conditions remaining un- 
changed), would certainly bring back again our present milder 
climate. The change either way would not probably bo very 
great, but it might be sufficient to bring the snow-line down to 
3000 feet in Scotland, so that all the higher mountains had their 
tops covered with perpetual snow. This perpetual snow, down 
to a fixed line, would be kept up by the necessary supply of 
snow falling during autumn, winter, and spring, and this would, 
as we have seen, depend mainly on the increased length and 
greatly increased cold of the winter. As both the duration and 
the cold of winter decreased, the amount of snow would certain- 
ly decrease; and of this lesser quantity of snow a larger propor- 
tion would be melted by the longer, though somewhat cooler, 



150 



ISLAND LIFE. 



CtART I. 



summer. Tins would follow because tlie total amount of 8im 
lieat received during the eummer would be the eaiiie as before, 
while it would act'on » less quantity of snow ; there would thus 
be a smaller surface to reflect tiie heat, and a mnallcr condensing 
area to produce fogs, while the diiniiiiehed intensity of the Eun 
would produce a less dense canopy of clouds, which have been 
shown to be of prime iinpoi'tancc in cheeking the melting of 
snow by the sun. We liave considered this case, for simplicity 
of reasoning, on the supposition that all geographical and phys- 
ical causes remained imehanged. But if an alteration of the 
climate of the whole north temperate and arctic zones occurred, 
as here indicated, this would certainly affect both the winds and 
enrrents, in the manner already explained (see p. 135), so as to 
react upon climate and increase the differences produced by 
phases of precession. How far that effect wonid be again in- 
creased by corresponding but opposite changes in the Southern 
Hemisphere it is impossible to say. It may be that existing ge- 
ographical and physical conditions are there such potent agents 
in producing a state of glaciation that no change in the phases 
of precession would materially affect it. Still, aa the climate of 
tlie whole Soutliem Hemisphere is dominated by the great mass 
of ice within the Antarctic Circle, it seems probable that if the 
winter were shorter and the summer longer the quantity of ice 
would slightly diminish; and this would again react on the 
northern climate as alitady fully explained. 

The Eis»ential I'rinnple of Vlhimtal Change Restated. — The 
preceding discussion has been somewhat lengthy, owing to tlie 
varied nature of the facts and arguments adduced and the ex- 
treme complexity of the subject. But if, as I venture to hope, 
the principle here laid down is a sound one, it will be of the 
greatest assistance in clearing away some of the many difficulties 
that beset the whole question of geological climates. This prin- 
ciple is, briefly, that the great features of climate are determined 
by a combination of causes, of which geographical conditions 
and the degree of eccentricity of the earth's orbit are by far tlie 
most important; that when these combine to pTOdnee a eevcie 
glacial epoch, the changing phases of precession every 10,500 
years have very little, if any, effect on the character of the cH- 



Chap. VIII.] THE CAUSES OF GLACIAL EPOCHS. 151 

mate, as mild or glacial, though it may modify the seasons ; but 
when the eccentricity becomes moderate and the resulting cli- 
mate less severe, then the changing phases of precession bring 
about a considerable alteration, and even a pai*tial reversal, of 
the climate. 

The reason of this may perhaps be made clearer by consider- 
ing the stability of either very cold or very mild conditions, and 
the comparative instability of an intermediate state of climate. 
When a country is largely cove'red with ice, we may look upon 
it as possessing the accumulated or stored-np cold of a long se- 
ries of preceding winters; and, however much heat is poured 
upon it, its temperature cannot be raised above the freezing, 
point till that store of cold is got rid of — that is, till the ice is 
all melted. But the ice itself, when extensive, tends to its own 
preservation, even under the influence of heat ; for the chilled 
atmosphere becomes filled with fog, and this keeps oflf the sun 
heat ; and then snow falls even during summer, and the stored-up 
cold does not diminish during the year. When, however, only 
a small portion of the surface is covered with ice, the exposed 
earth becomes heated by the hot sun, this warms the air, and the 
warm air melts the adjacent ice. It follows that, towards the 
equatorial limits of a glaciated country, alternations of climate 
may occur during a period of high eccentricity ; while nearer the 
pole, where the whole country is completely ice-clad, no amelio- 
ration may take place. Exactly the same thing will occur in- 
versely with mild arctic climates ; but this is a subject which will 
be discussed in the next chapter. 

This view of the character of the last glacial epoch strictly 
corresponds with the facts adduced by geologists. The inter- 
glacial deposits never exhibit any indication of a climate whose 
warmth corresponded to the severity of the preceding cold, but 
rather of a partial amelioration of that cold ; while it is only the 
very latest of them, which we may suppose to have occurred 
when the eccentricity was considerably diminished, that exhibit 
any indications of a climate at all warmer than that which now 
prevails.* 

' In fi recent number of the Geological Magazine (April, 1880) Mr. SenrleA V. 



Probable Date of the Glacial Epoch. — Tlie state of extreme 
glaciatioii in the Northern Hemisphere, of which we gave a gen- 
eral description at the commencement of the preceding chapter, 
is a fact of which there can be no donbt whatever, and it oc- 
curred at a period so recent, geologically, that all the mollnsca 
were the same as speciea still living. There is clear geological 
proof, however, that considerable changes of sea and land, and a 
large amount of valley -denudation, took place during and since 
the glacial epoch ; wiiile, on the other hand, the surf ace-markings 
produced by the ice have been extensively preserved ; and, tak- 
ing all these facts into consideration, the i)eriod of about 200,000 
years since it reached its maximum, and about 80,000 years 
since it passed away, is generally considered by geologists to be 



Wood nililitco wlinc lia cuiiBidei's to bo the "candusive olijeclion" to Dr. Croll's eo- 
centrkily Elieor]-, ivliitli in, lliat iluiiiig tlie Inst gliicini epocli Eurn|>e aiiij Nnrlli 
j\mctii:a ncre glnciuteil ver; taucli in proportion to tlieir respective climntcs now, 
ivliich are genemlly nilmiited to be due to i)ie distribution of ocennic cnrrcnis. But 
Dr. CroU adinili liit theory "to be liaseluss unleu Iliere iraa n complete diversion of 
ths u'omi ocoun currents from the liemispfaera glnciaied,"in whldi cnse there onght 
10 be nodiHerence in the extant ofglncinlion in Enropennd No it h America. Wlieth- 
eror not tliisisncorrcct ilntement ofDr. Crull's llicory, the abave olijoeiiun cevCninly 
Joes not apply to ilie views licre n<ttocnted; but ns I also hold (bo "cecentridiy 
Tlieory " in a roodiHed form, it mty be as well to show nliy It does nqi apply. Iti 
the first iilnce, I do not believe that tlie Gulf Sd'eAta wns "completely direnod " dur- 
ing the glacial epoch, but that it was diminished in furce, and(Bidcsciibcdon p. ISC) 
partli/ diverted souliin'nrd. A portion of ill intluenco would, however, aiill retnnin 
lu cnuse k diflerence between the climnlca of tlie two sides of llie Allniitic ; and to 
ihi> musi be added two other cansei— -the fiir grenter penelrutiun of warm sea-water 
into the Enropenn than into itie North American continent, and llie proximity to 
America of ilio enorrooiia ice- producing mius of Greenland. Vie linve thus three 
distinct cnuiies, nil combining to produce a mure severe winter climate nn ilie west 
than on the enal of the Atlantic duiins the glndalepiwh ; and though the firil of these 
— ibe Quif Stream—vms not ninrly so powerful ns it b now, neither is the dllTerence 
•ndicnied by the ice-extension in the two conntriei so gi-enl ai the present ditterence 
of winter lempemiurc. which is the eswntini point to bo considered. The icc-shect 
of the United Sinies is usunlly supposed to have extended about ten. or, ni most, 
iwoli-e, degrees farther south ihnn it did in Weilcm Europe, wiiereas we must go 
lu-enty degrees farther south in the former country to ubtnin the same mean winter 
lompemturo ue find In the Inltcr. as miiy be teen by examining any map of winter 
inflliiennnls. Tliis diderenco very f.iirly conespundi to the difierence of conditions 
existing during the ghwini epoch and the present lime, so fat a% wc ni-o able to eiii- 
mnio them, and it certainty ttffurdi no grounds ofohjeciion to the theory by which 
ilic glncintion u hero exphiinod. 



Chap. VIII.] THE CAUSES OF GLACIAL EPOCHS. 153 

ample. There seems, therefore, to be little doubt that in in- 
creased eccentricity we have found one of the chief exciting 
causes of the glacial epoch, and that we are therefore able to fix 
its date with a considerable probability of being correct. The 
enormous duration of the glacial epoch itself (including its in- 
terglacial mild or warm phases) as compared with the lapse of 
time since it finally passed away is a consideration of the great- 
est importance, and has not yet been taken fully into account 
in the interpretation given by geologists of the physical and 
biological changes that were coincident with and probably de- 
pendent on it. 

Changes of the Sea-level Dependent on Glaciation, — It has 
been pointed out by Dr. CroU that many of the changes of 
level of sea and land which occurred about the time of the 
glacial epoch may be due to an alteration of the sea-level caused 
by a shifting of the earth's centre of gravity ; and physicists 
have generally admitted that the cause is a real one, and must 
have produced some effect of the kind indicated. It is evident 
that if ice-sheets several miles in thickness were removed from 
one polar area and placed on the other, the centre of gravity of 
the earth would shift towards the heavier pole, and the sea 
would necessarily follow it, and would rise accordingly. Ex- 
treme glacialists have maintained that during the height of the 
glacial epoch an ice-cap extended from about 50° N. lat. in 
Europe, and 40° N. lat. in America, continually increasing in 
thickness till it reached at least six miles thick at the pole ; but 
this view is now generally given up. A similar ice-cap is, how- 
ever, believed to exist on the antarctic pole at the present day, 
and its transferrence to the Northern Hemisphere would, it is 
calculated, produce a rise of the ocean to the extent of 800 or 
1000 feet. We have, however, shown that the production of 
any such ice-cap is improbable, if not impossible, because snow 
and ice can only accumulate where precipitation is greater than 
melting and evaporation, and this is never the case except in 
areas exposed to the full influence of the vapor-bearing winds. 
The outer rim of the ice-sheet would inevitably exhaust the air 
of so much of its moisture that what reached the inner parts 
would produce far less snow than would be melted by the long 



ISLASD LIFE. 



[P*» 



hot days of Binnnicr. Tlic accnniulntions of ice were therefore 
probahly confined, in tlio Nortlicni Hemisphere, to tlie coasts 
exposed to moist wiiide, and where elevated land and mowntnin- 
rnnges afforded condenaera to initiate the process of gluciation ; 
and we have already seen that the evidence strongly supports 
this view. Eveu with this limitation, however, the mass of ac- 
cumulated ice woiitd be enorinoiis, as indeed we have positive 
evidence tiiat it was, and might have caused a snfBcient shifting 
of the centre of gravity of the earth to produce a submergence 
of about 150 or 200 feet. 

But this would only be the case if the accumnlation of ice on 
one pole was accompanied by a diminution on the other, and 
tJiis may have occurred to a limited extent during the earlier 
stages of the glacial cpocli, when alternations of warmer and 
colder periods would bo caused by winter occurring in perihelion 
or aphelion. If, however, as we maintain, no such alternations 
occurred when the eccentricity was near its maximum, then the 
ice would accumulate in the Southern Ilomisphere at the same 
time as in the Northern, unless changed geographical conditions, 
of which wo have no evidence whatever, prevented such accu- 
mulations. That there was such a greater accunmlation of ice is 
shown by the traces of ancient glaciers in the Southern Andes 
and in New Zealand, and also, according to several writers, in 
South Africa: and the indications in all these localities point to 
a period so recent that it must almost certainly have been con- 
temporaneous with the glacial period of the Northern Hemi- 
sphere.' This greater accumulation of ice in both hemispheres 



■ The reranE exienrive Blnciniion of New Zcnlnnd it generally imputeil hy the local 
g«ologiaiB ta n grenler elevniiun of the land ; bul I connoi lielgi belisvmg that ilia 
high pbaio of eccenirieiiy which caiiied our own glncial epoch wna, nt nil evenu, au 
Msigting cnase. Tliis ia rendei'cd more prohRhle if Inken in connectbn with Iho 
tulloiving very ileliniie Ratement of gUi-inl ranrkingi In Soalh Africa. Capinin 
Arlvard, in tiii "Trnnivuil of To-day" (|). tTI), ajt, "It will be inierratlBK to 
(tfologiits nnd oihera lo learn that ilia entire country, from lite miinmiiB of ihe 
Qunlhlnnitm lo [lie junction of lite VnnI nnd Omngc riven, diowa mnrk* of having 
hnn sne[it over, nnd that at no very diilnnt period, by rnsl mustcs of ice fi^m eatt 
to tvsHl, The virintinns ore plainly vialble, acarring the older rovka, nnd marking 
llie hill-siilcs — getting lower nnd lower nnd Ims viiiUls n*. desecndlng from (lie 
munntiiiiis, the kii]'ji(Mi (smull hlU9]g[nnd uider npavl ; linr, wlieieit-rthe hUlt nniruir 



Chap. VIII.] THE CAUSES OF GLACIAL EPOCHS. 155 

would lower the whole ocean by the quantity of water abstracted 
from it, while any want of perfect synchronism between the 
decrease of the ice at the two poles would cause a movement of 
the centre of gravity of the earth, and a slight rise of the sea- 
level at one pole and depression at the otiier. It is also gener- 
ally believed that a great accumulation of ice might cause sub- 
sidence by its pressure on the flexible crust of the earth, and we 
thus have a very complex series of agents leading to elevations 
and subsidences of limited amount, such as seem always to have 
accompanied glaciation. This complexity of the causes at work 

towards each other, again showing how the vast ice-fields were cliecked, throuTi up, 
and raised nguinst their eastern extremities." 

This passage is evidently written by a person familiar with the phenomena of 
glaciation ; and as Captain A ylward's preface is dated from Edinburgh, lie lias prob- 
ably seen similar markings in Scotland. The country described consists of the most 
extensive and lofty plateau in South Afiica, rising to a mpuntain-knot with peaks 
more than 10,000 feet high, thus offering an appropriate area for the condensation 
of vapor and the accumulation of snow. At present, however, the mountains do not 
reach the snow-line, and there is no proof that they have been much higher in recent 
times, since the coast of Natal is now said to be rising. It is evident that no slight 
elevation would now lead to the accumulation of snow and ice in these motmtains, 
situated as they are between 27° and 30° S. lat. ; since the Andes, which in 32° 
S. lat. reach 23,300 feet high, and in 28° S. lat. 20,000, with far more extensive 
plateaus, produce no ice-fields. We cannot, therefore, believe that a few thourand 
feet of additional elevation, even if it occurred so recently as indicated by the pres- 
ence of striations, would have produced the remarkable amount of glaciation above 
described ; while from the analogy of the Northern Hemisphere we may well believe 
that it was mainly due to the same high eccentricity that led to the glaciation of 
Western and Central Europe and Eastern North America. 

These observations confirm those of Mr. G. W. Stow, who, in a paper published 
in the (^arterly Journal of the Geological Society (Vol. XXVII., p. 539), describes 
similar phenomena in the same mountains, and also mounds and ridges of unstratified 
clay packed with angular boulders; while farther south the Stormberg Mountains 
are said to be similarly glaciated, with immense accumulations of morainic matter in 
all the valleys. We have here all the chief surface phenomena characteristic of a 
glaciated country only a few degrees south of the tropic; and, taken in connection 
with the evidence of Professor Hartt, who describes true moraines near Rio Ja- 
neiro, situated on the tropic itself, we can hardly donbt the occurrence of some 
general and wide-spread cause of glaciation in the Southern Hemisphere at a period 
so recent that the superficial phenomena are as well preserved as in Europe. Such 
evidences of recent glaciation in the Southern Hemisphere are quite inexplicable 
without calling in the aid of the recent phase of high eccentricity ; and they may be 
fairly claimed as adding another link to the long chain of argument in favor of the 
theorv here advocated. 



1S6 



ISLAND XJFB. 



[Paw I. 



may explain the somewhat contradictory evidence as to rise and 
fall of land, some authors muintaining that it stood higher, and 
others lower, during the glacial period. 

The Slate of the Planet Mars, ew Bearing on Vie Theory of 
Jiccentrk-Uy, «# a Valise of Glacial I'erioda. — It is well known 
that tbo polar regions of the planet Mars are covered with white 
patches or disks, which undurgo considerable alterations of size 
according as they are more or less exposed to the sun's rays. 
They have tlierefoi'e been generally considered to be snow or 
ice caps, and to prove that Mars is now nndei;going something 
like a glacial period. It uiust always be remembered, however, 
tliat we are very ignorant of the exact physical conditions of 
the snrface of ifars. It appears to have a cloudy atmosphere 
like our own, but the gaseous composition of that atmosphere 
may be different, and the clouds may be formed of other matter 
besides aqueous vapor. Its much smaller mass and attractive 
power must have an effect on tiie nature and extent of these 
clouds, and the boat of the sun may coUBetinently be modified 
in a way quite different from an)'thing that obtains upon our 
earth. I^earing these diliiculties and uncertainties in mind, let 
us see what arc the actual facts connected witli the supposed 
polar snows of Mars.' 

Mare offers an excellent subject for comparison with the eartli 
as regards this question, because its eccentricity is now a little 
greater than the maximum eccentricity of the earth during the 
last million years (Mars eccentricity, 0.0931 ; earth eccentricity, 
850,000 TCiii-s back, 0,0707) ; the inclination of its axis is also a 
little greater than ours (Mare, 28° 51' ; earth, 23° 27"), and botli 
Mars and the earth are so situated that ihcy now have the win- 
ter of their Jforthern hemispberee in perihelion, that of their 
Southern hemispheres being in aphelion. If, therefore, the phys- 
ical condition of Mars were the same, or nearly the same, as that 
of the earth, all circumstances combine, aecoi-ding to Mr, Croll's 

'Tlie astronomical fiicls connecied wiih ilie morJoTia ntid ii|iponmnrc of llie plnnel 
are laken from « pnper ly Mr. lidwnrd Cnrp»ntor, M.A., in the Grologieal Mtiga- 
tint nf Mnrcli. 1ST7, ciiiiiled " EviJcnfc AtTuriled by Mur* on the Suljoct of GUcUl 
I'eriodi," but I arrire nt (omewhat ilitteKtit concluiioni from tli(w« of the wiiier of 
the pnper. 



Chap. VIII.] THE CAUSES OF GLACIAL EPOCHS. 157 

hypothesis, to produce a severe glacial epoch in its southerriy 
with a perpetual spring or summer in its northern^ hemisphere ; 
while, on the hypothesis here advocated, we should expect gla- 
ciation at both poles. As a matter of fact. Mars has two snow- 
caps of nearly equal magnitude at their maximum in winter, but 
varying very unequally. The northern cap varies slowly and lit- 
tle, the southern varies rapidly and largely. 

In the year 1830 the southern snow was observed, during the 
midsummer of Mars, to diminish to half its former diameter in 
a fortnight (the duration of such phenomena on Mars being 
reckoned in Martian months equivalent to one twelfth of a Mar- 
tian year). Thus on June 23 it was 11° 30' in diameter, and on 
July 9 had diminished to 5® 46', after which it rapidly increased 
again. In 1837 the same cap was observed near its maximum in 
winter, and was found to be about 35° in diameter. 

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

Mftj 4, Diameter of spot, 31° 24' 



June 4, 






28° 0' 


" 17, 






22° 64' 


July 4, 






18° 24' 


** 12, 






15° 20' 


** 20, 






18° 0' 



We thus see that Mars has two permanent snow-caps of nearly 
equal size in winter, but diminishing very unequally in summer, 
when the southern cap is reduced to nearly one third the size of 
the northern ; and this fact is held by Mr. Cai*penter, as it was 
by the late Mr. Belt, to be opposed to the view of the hemi- 
sphere which has winter in aphelion (as the southern now has 
both in the earth and Mars) having been alone glaciated during 
periods of high eccentricity.* 

* In an article in Nature of January 1, 1880, the Rer. T. W. Webb states that in 
1877 the pole of Mars (? the south pole) was, according to Schiaparelli, entirely free 
of snow, lie remarks also on the regular contour of the supposed snows of Mars as 
offering a great contrast to ours, and also the strongly marked dark border which has 
often been observed. On the whole, Mr. Webb seems to be of opinion that there can 
be no really close resemblance between the physical condition of the earth and Mars, 
and that any arguments founded on such supposed similarity are therefore antrust- 
worthv. 



ISLAND LIFE. 



[l'**T L 



Before, liowever, we cnii draw any conclusion from tlic ease 
of Mars, we must carefully scrutinize the facts and the condi- 
tions tbey imply. In the firet place, there is evidently this rad- 
icul difference between the state of Mara now and of the earth 
during a giaeial period — that Mni-s hns no great ice-sheets spread- 
ing over her temperate zone as the earth undoubtedly had. This 
we know from the fact of the rapid disappearance of the white 
patches over a belt three degrees wide in a fortnight (equal to a 
width of abont 100 njiles of our measure), and in the Northern 
Hemisphere of eight degrees wide (about 2S0 miles) between 
May 4 and July 13. Even with our much more powerful snn, 
which gives as more than twice as much lieat as Mars receives, 
no such diminntion of an ice-sheet, or of glaciers of even mod- 
erate thickness, could possibly occur; but the phenomenon is, 
on the contrary, exactly analogous to what actually takes place 
on tho plains of Siberia in summer. These, as I am informed by 
Mr. Sechohm, are covered with snow during winter and spring 
to a depth of six or eight feet, which diminishes very little even 
under tho hot suns of May, till warm winds combine with tlio 
sun in June, when in about a fortnight the whole of it disap- 
pcni'S, and a little later the whole of Northern Asia is free from 
its winter covering. As, liowever, tho snn of Mars is so much 
less powerful than ours, we may be sure that the snow (if it is 
real snow) is much leas thick — -a mere surface-coaling in fact, 
such as occurs iu parts of Russia where the precipitation is less, 
and tho snow accordingly dues not exceed two or three feet in 
thickness. 

We now see the reason why the southern pole of Mars parts 
with its white covering so much quicker and to so nmch greater 
an extent than the northern, for the south pole during summep 
is nearest the sun, and, owing to the great eccentricity of Mars, 
would have about ono third more heat than during the sunmior 
of the Northern Hemisphere ; and this gi-eater heat would cause 
tho winds from the equator to be both warmer and more power- 
ful, and able to produce tho same effects cm tho scanty Martian 
snows as they produce on our northern plains. TJie reason why 
both poles of Mars arc almost equally snow-covered in winter is 
not diliicuU to understand. Owing to the greater obliquity of 



Chap. VIII.] THE CAUSES OF GLACIAL EPOCHS. 159 

the ecliptic, and the much greater length of the year, the polar 
regions will be subject to winter darkness fully twice as long as 
with us, and tlie fact that one pole is nearer the sun during this 
period than the other at a corresponding period will therefore 
make no perceptible difference. It is also probable that the two 
poles of Mars are approximately alike as regards their geograph- 
ical features, and that neither of them is surrounded by very 
high land on which ice may accumulate. With us at the pres- 
ent time, on the other hand, geographical conditions completely 
mask and even reverse the influence of eccentricity, and that of 
winter in perihelion in the Northern and summer in perihelion 
in the Southern Hemisphere. In the north we have a preponder- 
ance of sea within the Arctic Circle, and of lowlands in the tem- 
perate zone. In the south exactly opposite conditions prevail, 
for there we have a preponderance of land (and much of it high 
land) within the Antarctic Circle, and of sea in the temperate 
zone. Ice, therefore, accumulates in the south, while a thin coat- 
ing of snow, easily melted in summer, is the prevalent feature in 
the north ; and these contrasts react upon climate to such an ex- 
tent that, in the Southern Ocean, islands in the latitude of Ire- 
land have glaciers descending to the level of the sea, and con- 
stant snow-storms in the height of summer, although the sun is 
then actually nearer the earth than it is during our northern 
summer! 

It is evident, therefore, that the phenomena presented by the 
varying polar snows of Mars are in no way opposed to that 
modification of Dr. Croll's theory of the conditions which 
brought about the glacial epochs of our Northern Hemisphere 
which is here advocated, but are perfectly explicable on the 
same general principles, if we keep in mind the distinction be- 
tween an ice-sheet — which a summer's sun cannot materially di- 
minish, but may even increase by bringing vapor to be con- 
densed into snow — and a thin snowy covering which may be 
annually melted and annually renewed with great rapidity and 
over large areas. Except within the small circles of perpetual 
polar snow, there can- at the present time be no ice-sheets in 
Mars ; and the reason why this permanent snowy area is more 
extensive around the northern than around the southern pole 



160 ISLAND LIFE. [Part I. 

may be partly dne to higher land at the north, but is perhaps 
sufficiently explained by the diminished power of the summer 
sun, owing to its greatly increased distance at that season in 
the Northern Hemisphere, so that it is riot able to melt so much 
of the snow which has accumulated during the long night of 
winter. 



Chap. IX.] ANCIENT GLACIAL EPOCHS. 161 



CHAPTER IX. 

ANCIENT GLACIAL EPOCHS, AND MILD CLIMATES IN THE ARC- 
TIC REGIONS. 

Dr. Croll's Views on Ancient Glncinl Epochs. — Effects of Denudation in Destroying 
tlie Evidence of Remote Glacial Epochs. — Rise of Sea-level Connected with 
Glacial Ei>ochs a Cause of Further Denudation. — What Evidence of Early Glacial 
Epoclis may be Expected. — Evidences of Ice-action daring the Tertiary Period. 
— The Weight of the Negative Evidence. — Temperate Climates in the Arctic Re- 
gions. — Tlie Miocene Arctic Flora. — Mild Arctic Climates of the Cretaceous 
Period. — Stratigniphical Evidence of I^ng-continued Mild Arctic Conditions. — 
Tiie Causes of JNIild Arctic Climates. — Geographical Conditions Favoring Mild 
Northern C'limates in Tertiary Times. — The Indian Ocean as a Source of Heat in 
Teriiiiry Times. — Condition of North America during the Tertiary Period. — 
EtFect of High Eccentricity on Waim Polar Climates. — Evidences as to Climate 
in the Secondary and Palajozoic Epochs. — Warm Arctic Climates in Early Sec- 
ondary and Palaeozoic Times. — Conclusions as to the Climates of Secondary and 
Tertiary Periods. — General View of Geological Climates as Dependent on the 
Physical Features of the Earth's Surface. — Estimate of the Comparative Effects 
of Geographical and Physical Causes in Producing Changes of Climate. 

If wo adopt tlie view set forth in the preceding cliapter as 
to the character of the glacial epoch and of the accompanying 
alternations of climate, it must have been a very important 
agent in producing changes in the distribution of animal and 
vegetable life. The intervening mild periods, which almost 
certainly occurred during its earlier and later phases, were some- 
times more equable than even our present insular climate, and 
severe frosts were probably then unknown. During the eight 
or ten thousand yeare that each such mild period lasted, some 
portions of the north temperate zone which liad been buried in 
snow or ice would become again clothed with vegetation and 
stocked with animal life, both of which, as the cold again came 
on, would be driven southward, or perhaps partially extermi- 
nated. Forms usually separated would thus be crowded together, 
and a struggle for existence would follow which must have led 

11 



162 ISLAND LIFE. [Part I. 

to the modification or the extinction of many species. When 
the snrvivors in tlie struggle had reached a state of equilibrium, 
a fresh field would be opened to them by the later ameliorations 
of climate; the more successful of tlie survivors would spread 
and multiply ; and after this had gone on for tliousands of gen- 
erations, another change of climate, another southward migra- 
tion, another struggle of northern and southern forms, would 
take place. 

But if the last glacial epoch has coincided with, and has been 
to a considerable extent caused by, a high eccentricity of the 
earth's orbit, we are naturally led to expect that earlier glacial 
epochs would have occurred w henever the eccentricity was un- 
usually large. Dr. CroU has published tables showing the vary- 
ing amounts of eccentricity for three million years back ; and 
from these it appears there have been many periods of high ec- 
centricity, which has often been far greater than at the time of 
the last glacial epoch.* The accompanying diagram has been 
drawn from these tables, and it will be seen that the highest 
eccentricity occurred 850,000 years ago, at which time the dif- 
ference between the sun's distance at aphelion and perihelion 
was thirteen and a half inillions of miles, whereas during the 
last glacial period the maximum difference was ten and a half 
million miles. 

Xow, judging by the amount of organic and physical change 
that occurred during and since the glacial epoch, and that which 
has occurred since the Miocene period, it is considered probable 
that this maximum of eccentricity coincided with some part of 
the latter period ; and Dr. Croll maintains that a glacial epoch 
must then liave occurred surpassing in severity that of which 
we have such convincing proofs, and consisting like it of alter- 
nations of cold and warm phases every 10,500 years. The 
diagram also shows us another long-continued period of high 
eccentricity from 1,750,000 to 1,950,000 years ago, and yet 
another almost equal to the maximum 2,500,000 years back. 
These may perhaps have occurred during the Eocene and Cre- 



* London^ Edinburgh^ and Dublin Philosophical Magazine^ Vol. XXXVI., pp. 144- 
]oO(lS68). 



CHiP.lX] ANCIENT GLACIAL ETOCHS. 

taceous epochs respectively, or nil 
may liavo been included n'ithin the 
limits of the Tertiary period. As 
two of these liigh eccentricities 
greatly exceed that which caused 

our glacial epoch, while the thud is u 

almost equal to it and of longer du- | 

ration, tliey seem to afford us the k 

ineaiis of testing rival theoiies of S 

the causes of glaciation. If, as Dr 3 

Croll argues, higii eccentricity is the S 

great and dominating agency in s 

bringing on glacial epociis, geo- n 

graphical changes being suboidi- z 

nate, then there innst ha\e been g 

glacial epochs of great seventy at § 

all these three periods ; while if lie | 

is also correct in supposing that the « 

alternate phases of precession would » 

inevitably produce glaciation in one s 

hemisphere and a proportionately o 

mild and equable climate in the s 

opposite hemisphere, tlien we sliould ° 

havo to look for evidence of ex- ■= 

ceptioiialty warm and exceptionally ^ 

cold periods occurring alternately, S 

and with several repetitions, with- g 

in a space of time which, geo- " 

logically speaking, is very sliort in- 5 

deed. | 

Let us, then, inqniie first into the ■* 

character of the evidence we shonld f^ 

expect to find of such changes of s* 
climate, if they have occurred; we 
shall tlien be in a better position to 
estimate at its proper value the evi- 
dence that actually exists, and, after 
giving it due weiglit, to arrive at 



^^ 



u Si 



ISLAND LIFE. 



[Paw I, 



some coneliision na to the theory that best exjilains and har- 
monizes it. 

Effects of Dentulaiion in Destroying th£ Emdc-nce of Remote 
Olaeial £poch». — It may be enpposed tliat if earlier glacial 
epochs than the last did really occur, wc ought to meet with 
some evidence of the fact corresponding to that -which has 
satisfied us of tlie extensive recent glaciation of the Nortliern 
Hemisphere; but Dr. Croll and other writers have ably argned 
that no 6uch evidence is likely to be found. It is now generally 
admitted that subaerial denudation is a much more powerful 
agent in lowering and modifying the surface of a country than 
was formerly Bopposcd. It lias, in fact, been proved to he so 
powerful that tho difficulty now felt ia, not to account for the 
denudation whic-h can be proved to have occurred, but to ex- 
plain the apparent persistence of superficial features which 
ought long ago to have been destroyed. 

A proof of the lowering and eating-away of the land surface 
which every one can nndei'stand ia to be fouud in the quantity 
(if solid matter carried down to the eca and to low grounds by 
rivers. This is capable of pretty accflrnte measurement, and has 
been so measured for Beveral rivers, large and sniali, in different 
parts of the world. The details of these measurements will he 
given in a future chapter, and it is only necessary here to state 
that the average of them all gives ns this result — that one foot 
must be taken off the entire surface of the land each 3000 years, 
in order to produce tlie amount of sediment and matter in solu- 
tion which is actually carried into the sea. To give an idea of 
the limits of variation in different rivers, it may bo mentioned 
that the Mississippi is one which denudes its valley at a slow- 
rate, taking COOO years to remove one foot; while tho Po is the 
most rapid, taking only 7'2i) years to do the same work in iu 
valley. Tho cause of this difference is very easy to understand. 
A large part of the area of tho Mississippi basin consists of tlio 
almost rainless prairie and desert regions of the west, while its 
sources are in comparatively arid mountains with scanty snow- 
fields or in a low forest-clad jilatean. The Po, on the other 
hand, is wholly in a district of abundant rainfall, while its 
sources are spread over a great amphitheutre of snowy Alps 



Chap. IX.] ANCIENT GLACIAL EPOCHS. 165 

nearly 400 miles in extent, where the denuding forces are at a 
maximnm. As Scotland is a mountain region of rather abundant 
minfall, the denuding power of its rains and rivers is probably 
rather above than under the average ; but, to avoid any possible 
exaggeration, we will take it at a foot in 4000 years. 

Now, if the end of the glacial epoch be taken to coincide with 
the termination of the last period of high eccentricity, which 
occurred about 80,000 years ago (and no geologist will consider 
this too long for the changes which have since taken place), it 
follows that the entire surface of Scotland must have been since 
lowered an average amount of twenty feet. But over large areas 
of alluvial plains, and wherever the rivers have spread during 
floods, the ground will have been raised instead of lowered ; and 
on all nearly level ground and gentle slopes there will have been 
comparatively little denudation ; so that proportionally much 
more must have been taken away from mountain-sides and from 
the bottoms of valleys having a considerable downward slope. 
One of the very highest authorities on the subject of denuda- 
tion, Mr. Archibald Geikie, estimates the area of these more rap- 
idly denuded portions as ^ly one tenth of the comparatively 
level grounds, and he further estimates that the former will be 
denuded about ten times as fast as the latter. It follows that the 
valleys will be deepened and widened on the average about five 
feet in the 4000 years instead of one foot ; and thus many val- 
leys must have been deepened and widened one hundred feet, 
and some even more, since the glacial epoch, while the more 
level portions of the country will have been lowered, on the av- 
erage, only about two feet. 

Now, Dr. Croll gives us the following account of the present 
aspect of the surface of a large part of the country : 

'' Go where one will in the lowlands of Scotland and he shall 
hardly find a single acre whose upper surface bears the marks 
of being formed by the denuding agents now in operation. He 
will observe everywhere mounds and hollows which cannot be 
accounted for by the present agencies at work. ... In regard 
to the general surface of the country, the present agencies may 
be said to be just beginning to carve a new line of features out 
of the old glacially formed surface. But so little progress has 



ISLAND LIFE. 



[Paki I. 



yet been made tliat the bames, gravel-inoiinds, knoUs of boulder 
cl«j, etc., still retain in moat cases their original form.'" 

Tlie facte here seein a little inconsietctit, and wo must suppose 
that Dr. Croll Laa sotiiewhat exaggerated the universality and 
complete preservation of the glaciated surface. The amount of 
average denudation, however, Is not a matter of opinion, but of 
measurement; aud its conBequenees can in no way be evaded. 
They are, moreover, strictly proportionate to the time elapsed ; 
and if so much of the old surface of the country Las certainly 
been remodelled or carried into the sea since the last glacial 
epoch, it becomes evident that any surface phenomena produced 
by still earlier glacial epochs must have long since entirely dis- 
appeared. 

Jiii^ ofihe lka4evel C<mnecl<tfl with Glacial Epochs a Cause 
of Ji'urther Denudatimi. — There is also another powerful agent 
that must have assisted in the destruction of any such surface 
deposits or markings. During the last glacial epoch itself there 
were several oscillationH of the land, one at least of considerable 
extent, during wliicli shell-bearing gravels were deposited on the 
flanks of the Welsh and Irish mountains, now 1300 feet above 
sea-level; and there is reason to believe that other enbsidencee 
of the same area, thongh perhaps of less extent, may have oc- 
cuired at various times during the Tertiary period. Many writ- 
ers, as we have seen, connect this subsidence with the glacial pe- 
riod itself, tlic unequal amount of ice at the two poles causing 
the centre of gravity of the earth to be displaced, when, of 
course, the surface of the ocean will conform to it, aud appear 
to rise in the one hemisphei'e and sink in the other. If this is 
the case, subsidences of the land are natural concomitants of a 
glacial period, and will powerfully aid in removing all evidence 
of its occurrence. We have seen reason to believe, however, that 
during the height of the glacial epoch the extreme cold persisted 
through the successive phases of procession ; and if so, both polar 
nrcaa wonld probably be glaciated -.yi once. This would cause the 
abstraction of a large quantity of water from the ocean, and « 
proportionate elevation of the land, which would react on the 



' "Climnls nnj Tiiuo in llieir Geologiciil Hclniionc," p. .111. 



CuAP. TX.] ANCIENT GLACIAL EPOCHS. 167 

accumulation of snow and ice, and thus add another to tliat won- 
derful series of physical agents which act and react on each 
other so as to intensify glacial epochs. 

But whether or not these causes would produce any impor- 
tant fluctuations of the sea-level is of comparatively little impor- 
tance to our present inquiry, because the wide extent of marine 
Tertiary deposits in the Northern Hemisphere, and their occur- 
rence at considerable elevations above the present sea-level, af- 
ford the most conclusive proofs that great changes of sea and 
land have occurred throughout the entire Tertiary period ; and 
these repeated submergences and emergences of the land, com- 
bined with subaerial and marine denudation, would undoubtedly 
destroy all those superficial evidences of ice-action on which we 
mainly depend for proofs of the occurrence of the last glacial 
epoch. 

What Evidence of Early Glacial Epochs may be Ej^pected. — 
Although we may admit the force of the preceding argument as 
to the extreme improbability of our finding any clear evidence 
of the superficial action of ice during remote glacial epochs, 
there is, nevertheless, one kind of evidence that we ought to 
find, because it is both wide-spread and practically indestruc- 
tible. 

One of the most constant of all the phenomena of a glaciated 
country is the abundance of icebergs produced by the breaking- 
off of the ends of glaciers which terminate in arms of the sea, or 
of the terminal face of the ice-sheet which passes beyond the 
land into the ocean. In both these cases abundance of rocks 
and debris, such as form the terminal moraines of glaciers on 
land, are carried out to sea and deposited over the sea-bottom of 
the area occupied by icebergs. In the case of an ice-sheet it is 
almost certain that much of the ground-moraine, consisting of 
mud and embedded stones, similar to that which forms the 
"till" when deposited on land, will be carried out to sea with 
the ice, and form a deposit of marine " till " near the shore. 

It has, indeed, been objected that when an ice-sheet covered an 
entire country there would be no moraines, and that rocks or 
debris are very rarely seen on icebergs. But during every gla- 
cial epoch there will be a southern limit to the glaciated area. 



and eveiywLere near tliie limit the mouii tain-tope will rise far 
above the ice and deposit on it great maBBea of debris ; and as 
the ice-sheet spreads, and again as it passes away, this moraiuc- 
forming area will successively occupy the whole country. But 
even such an ice-clad conutry as (Greenland is now known to 
have proti'nding peaks and rocky masses which give rise to mo- 
raines on its surface;' and, as rocks from Cnmberland and Ire- 
land woi-e carried by the ice-shoet to the Isle of Man, there must 
have been a very long period during which the ice-sheets of 
Britain and Ireland terminated in the ocean and sent off abun- 
dance of rock-laden bergs into the surrounding fleas ; and the 
same thing must have occurred along all the coaats of Northern 
Europe .ind Eastern America. 

"VVe cannot, therefore, doubt that throughout the greater part 
of the duration of a glacial epoch the seas adjacent to tlie glaci- 
ated countries would receive continual deposits of large rocks, 
rock-fiagmcuts, and gravel similai- to the material of modern 
and ancient moraines, and analogous to the drift and the numer- 
ous travelled blocks which the ice has undoubtedly scattered 
broadcast over every glaciated country; and these rocks and 
boulders would be embedded in whatever deposits were then 
forming, cither from the matter carried down by rivers or from 
the mud ground off the rocks and carried out to sea by the glac- 
iers themselves. Moreover, as icebergs float far beyond the lim- 
its of the countries which gave them birth, these ice-borne mate- 
rials would be largely embedded in deposits forming from the 
denudation of conutries which had never been glaciated, or from 
which the ice had already disappeared. 

But if every period of high eccentricity produced a glacial 
epoch of greater or lera extent and severity, then, on account of 
the frequent occurrence of a high phase of eccentricity during 
the 3,OliO,'H)0 years for which we have the tiibles, these houlder 
and I'ock-strewn deposits would be both numerous and exten- 
eive. 400,000 years ago the eccentricity was almost exactly the 
eame as it is now, and it continually increased from that time up 
to the glacial epoch. Now, if wc take double the present eccon- 



Chap. IX.] ANCIENT GLACIAL EPOCHS. 169 

ti'icity as being sufficient to produce some glaciation in the tem- 
perate zone, we find (by drawing out the diagram at p. 163 on 
a larger scale) that during 1,150,000 years out of the 2,400,000 
years immediately preceding the last glacial epoch, the eccentric- 
ity reached or exceeded this amount, consisting of sixteen sepii- 
rate epochs, divided from each other by periods varying from 
30,000 to 200,000 years. But if the last glacial epoch was at its 
maximum 200,000 years ago, a space of 3,000,000 years will cer- 
tainly include much, if not all, of the Tertiary period ; and even 
if it docs not, we have no reason to suppose that tlic character 
of the eccentricity would suddenly change beyond the 3,000,000 
years. 

It follows, therefore, that if periods of high eccentricity, like 
that which appears to have been synchronous with our last gla- 
cial epoch, and is generally admitted to have been one of its ef- 
ficient causes, always produced glacial epochs (with or without 
alternating warm periods), then the whole of the Tertiary de- 
posits in the north temperate and arctic zones should exhibit 
constantly alternating boulder and rock-bearing beds, or coarse 
rock-strewn gravels analogous to our existing glacial drift, and 
with some corresponding change of organic remains. Let us, 
then, see what evidence can be adduced of the existence of such 
deposits, and whether it is adequate to support the theory of re- 
peated glacial epochs during the Tertiary period. 

Evidences of Ice -action during the Tertiary Period. — The 
Tertiary fossils both of Europe and North America indicate 
throughout warm or temperate climates, except those of the 
more recent Pliocene deposits which merge into the earlier gla- 
cial beds. The Miocene deposits of Central and Southern Eu- 
rope, for example, contain marine shells of some genera now 
only found farther south, while the fossil plants often resem- 
ble those of Madeira and the Southern States of North America. 
Large reptiles, too, abounded ; and man-like apes lived in the 
south of France and in Germany. Yet in Northern Italy, near 
Turin, there are beds of sandstone and conglomerate full of 
characteristic Miocene shells, but containing in an intercalated 
deposit angular blocks of serpentine and greenstone often of 
enormous size, one being fourteen feet long, and another twen- 



170 



ISLAND LIFE. 



[P*»L 



ty-six fuel. Some of the blocks were observed by Sir Charles 
Lycll to be faintly striated and partly polisiied on one side, and 
they are scattered tJtrougli the beds for a tliickness of nearly one 
hundred and fifty feet. It is interesting tliat the particular bed in 
which the bloi-ks occur yields no organic remains, though these 
are plentifnl both in llie underlying and overlying beds, as if 
tlio cold of the icebergs had driven away the organisms adapted 
to live only in a comparatively warm sea. Rock similar in kind 
to these erratics occurs about twenty miles distant in the Alps. 

The Eocene period is even more characterifetically tropical in 
ils flora and fauna, since palms and Cyeaduceie, turtles, snakes, 
and crocodiles then inhabited England. Yet on the north side 
of the Alps, extending from Switzerland to Vienna, and also 
eoDth of the Alps near Genoa, there is a deposit of lincly strati- 
fied sandstone several thousand feet in thickness, quite destitute 
of organic remains, but containing, in several places in Switzer- 
land, enormous blocks eitiier angniar or partly rounded, and 
composed of oolitic limestone or of granite. Near the Lake of 
Thun some of the granite blocks found in this deposit are of 
enormous size, one of them being one hundred and tive feet 
long, ninety feet wide, and forty-tive feet thick ! The granite 
ie red, and of a peculiar kind which cannot be matched any wliei-o 
in the Alps, or indeed elsewhere. Similar erratics have also been 
found in beds of the same age in the Carpathians and in the 
Apennines, indicating probably an extensive Inland European 
sea into which glaciers descended from the surrounding nionn- 
tains, di'positing these erratics, and cooling the water so as to de- 
etrnytho moUuscaand other organisms which had previously in- 
habited it. It is to be observed thai wherever these erratics oc- 
cur they are always in the vicinity of great mountain-rnnges; 
and although these can be proved to liave been in great pait el- 
evated during the Tertiary period, we must also remember that 
they must have been since very niucli lowered by denudation, 
of the amount of which the enonnously thick Eocene and Mio- 
cene bedt* now forming portiims of them are in some degree a 
measure as well as a proof. It is not, therefore, at all improba- 
ble that during some part of the Tertiary period these moun- 
tains may liave been far higher than they are now, and this wo 



Chap. IX.] ANCIENT GLACIAL EPOCHS. 171 

know might be sufficient for the production of glaciers descend- 
ing to the sea-level, even were the climate of the lowlands some- 
what warmer than at present.* 

The Weight of the Negative Evidence, — But when we proceed 
to examine the Tertiary deposits of other parts of Europe, and 
especially of our own country, for evidence of this kind, not 
only is such evidence completely wanting, but the facts are of 
so definite a character as to satisfy most geologists that it can 
never have existed ; and the same may be said of temperate 
North America and of the arctic regions generally. 

In his carefully written paper on " The Climate Controversy," 
Mr. Searles V. Wood, Jr., remarks on this point as follows : 
"Now the Eocene formation is complete in England, and is ex- 
posed in continuous section along the north coast of the Isle of 
Wight from its base to its junction with the Oligocene (or Low- 
er Miocene according to some), and along the northern coast of 
Kent from its base to the Lower Bagshot Sand. It has been in- 
tersected by railway and other cuttings in all directions and at 
all horizons, and pierced by wells innumerable ; while from its 
strata in England, France, and Belgium the most extensive col- 
lections of organic remains have been made of any formation 
yet explored, and from nearly all its horizons, for at one place 
or another in these three countries nearly every horizon may be 
said to have yielded fossils of some kind. These fossils, however, 

* Professor J.W. Jiidd snys, " In the case of the Alps, I know of no glacial phenom- 
ena which are not capaible of being cxphiined, like those of New Zealand, by a great 
extension of the area of the tracts above the snow-line which would collect more ample 
sup])lies for the glaciers protruded into surrounding plains. And when we survey the 
grand panoramas of ridges, pinnacles, and peaks produced, fur the most part, by sub- 
aerial action, we may well be prepared to admit that before the inter\'ening ravines 
and valleys wei*e excavated, the glaciers shed from the elevated plateaus must have 
been of vastly greater magnitude than at present" ('* Contributions to the Study of 
Volcanoes," Geological Magazine^ 1876, p. i>36). Professor Judd applies these re- 
marks to the last as well as to previous glacial periods in the Alps ; but surely tiiere 
has been no sucii extensive alteration and lowering of the surface of the country since 
the erratic blocks were deposited on the Jura and the great moraines formed in North 
Italy, as tliis theory would im)»ly. We can hardly suppose wide areas to have been 
lowered thousands of feet by denudation, and yet have left other adjacent areas ap- 
fiarently untouched : and it is even very doubtful whether such an extension of the 
STiow-fields would alone suflSce for the effects which were cenainly produced. 



1T2 



ISLAND LIFE. 



[pAirr I. 



ivliethtu' tliey be the remains of a flora such as that of Sliep- 
pey, or of a vertebrate fauna oontaining the crocodilo and alli- 
gator, sach ns is yielded by beds indicative of terrestrial condi- 
tions, or uf a inolluscun assemblage such as is present iii tnarine 
or fluvio-iiiariue beds of tbo formation, are of nnmistaliably tropi- 
cal or subtropical character throughout; and no trace whatever 
Las appeared of the intercalation of ft glacial period, much less 
of successive intercalations indicative of more than one period 
of 10,500 yeare' glaciation. Nor can it be nrged that the glacial 
epochs of the Eocene in England were intervals of di-y land, 
and 60 have left no evidence of their existence behind them, be- 
cause a large part of the continuous sequence of Eocene deposits 
in this counti'y consists of alternations of tluviatile, fluvio-marine, 
und purely marino strata ; so that it seems impossible that dnr- 
ing the accumulation of the Eocene formation in England a gla- 
cial period could have occurred without its evidences being abun- 
dantly apparent. The Oligocene of Northern Germany and Bel- 
gium, and tlio Miocene of those countries and of France, have 
also afforded a rich niolluscan fauna, which, like that of the Eo- 
cene, has aa yet presented no indication of the intrusion of any- 
thing to interfere with its uniformly subti-opieal ebamcter.'' ' 

This is sufficiently striking; but when we consider that this 
enormous series of deposits, many thousand feet in thickness, 
consists wholly of alternations of clays, sands, marls, shales, or 
limestones, with a few beds of pebbles or conglomerate, not one 
of the whole series containing irregular blocks of foreign mate- 
rial, bouldcre, or gravel such as we liave seen to be the essential 
characteristic of a glacial epoch; and when we find that this 
very same general ehai-acter pervades all tiie extensive Tertiary 
dcposiCB of temperate North America — we shall, I think, be forced 
to the conclusion that no general glacial epochs couid have oc- 
curred during their formation. It must be remembered that 
the ''imperfection of the geological record" will not Iielp us 
here, because the series of Tertiary deposits is nnusnaliy com- 
plete, and we nuist snjtpose some deetnictive agency to have se- 
lected all the intercalated glacial beds and to have so completely 



Chap. IX.] MILD ARCTIC CLIMATES. 173 

made away with them that not a fragment remains, while pre- 
serving all, or almost all, the irUerglacial beds; and to have act- 
ed thus capriciously, not in one limited area only, but over the 
whole Northern Hemisphere, with the local exceptions on the 
flanks of great mountain-ranges already referred to. 

Temperate Clhnatea in the Arctic liegions. — As we have just 
seen, the geological evidence of the persistence of subtropical 
or warm climates in the north temperate zone during the greater 
part of the Tertiaiy period is almost irresistible ; and we have 
now to consider the still more extraordinary series of observa- 
tions which demonstrate that this amelioration of climate ex- 
tended into the arctic zone, and into countries now almost 
wholly buried in snow and ice. These warm arctic climates 
have been explained by Dr. CroU as due to periods of high ec- 
centricity with winter in perihelion, a theory which implies al- 
ternating opochs of glaciation far exceeding what now prevails ; 
and it is therefore necessary to examine the evidence pretty 
closely in order to see if this view is more tenable in the case 
of the north polar regions than we have found it to be in that 
of the north temperate zone. 

The most recent of these milder climates is perhaps indicated 
by the abundant remains of large mammalia — such as the mam- 
moth, woolly rhinoceros, bison, and horse — in the icy alluvial 
plains of Northern Siberia, and especially in the Liakhov Islands, 
in the same latitude as the North Cape of Asia. These remains 
occur not in one or two spots only, as if collected by eddies at 
the mouth of a river, but along the whole borders of the Arctic 
Ocean ; and it is generally admitted that the animals must have 
lived upon the adjacent plains, and that a considerably milder 
climate than now prevails could alone have enabled them to do 
so. At what period this occurred we do not know, but one of 
the last intercalated mild periods of the glacial epoch itself 
seems to offer all the necessary conditions. Again, Sir Edward 
Belcher discovered on the dreary shores of Wellington Channel, 
in 75^° N. lat., the trunk and root of a fir-tree which had evi- 
dently grown where it was found. It appeared to belong to 
the species Abies alba, or white fir, which now reaches 68° N. 
lat., and is the most northerly conifer known. Similar trees, one 



174 



ISLAND LIFE. 



CP« 



four feet iu eirciiiufereiico and thirty feet long, were found by 
Lieutenant Mecimni in Prince Patrick's Island, in lat. 76° 12' N. ; 
and other arctic explorers liavc found remains of trees ia higli 
latitudes wliicli iniiy all probably be referred to the eamo mild 
period as that of tlio iee-preserved arctic mammalia. 

Similar indications of a recent milder climate are fonud in 
Spitzbergen. Professor KordenskjOld says, "At various places 
on Spitzbergen, at the bottom of Lomme Bay, at Cape Thord- 
sen. in Biomstrand's strata in Advent Bay, there are found 
large and well-developed sheila of a bivalve, Mijtilus edulis, 
which is not now found living on the coasts of Spitzbergen, 
though on the west coast of Scandinavia it everywhere covers 
the rocks near the sca-sliore. These shells occur most plenti- 
fully in the bed of a river wliicli runs through Ileindeer Viilley 
at Capo Thordsen. They are probably washed out of a thin 
bed of sand at a height of abont twenty or thirty feet above the 
present sen-level, which is intersected by the river. The geologi- 
cal age of this bed cannot be very great, and it has clearly been 
formed since the present basin of tho Ice Sound, or at least the 
greater part of it, has been hollowed out by glacial action,'"' 

Tlie Miocene Arctic Flora. — One of the most startling and im- 
portant of the scientific discoveries of the last twenty years liu 
been that of the relics of a luxuriant Miocene flora in various 
parts of the arctiu regions, It is a discovery that was totally un- 
expected, and is even now considered by many men of science to 
be completely unintelligible ; hut it ia so thoroughly established, 
and it has such ;i direct and important bearing on the subjects we 
are diRciissing in tho present volume, that it is necessary to lay a 
tolerably complete outline of the facts before onr renders, 

The Miocene flora of temperate Europe was very like that of 
Eastern Asia, Japan, and the warmer part of Eastern North 
America of the present day. It is very richly represented iu 
Switzerland by well-preserved fossil remains, and after a close 
comparison with tho flora of other countries Professor Hccr 
concludes that tlic Swiss Lower Miocene flora indicates a climate 
corresponding to that of Louisiana, North Africa, and South 



' Geologieal Ma^jasinr, IB7C, "Geology of Spililjergen," ]>. 267, 



Chap. IX.] MILD ARCTIC CLIMATES. 175 

China, while tlie Upper Miocene climate of the same country 
would correspond to that of the south of Spain, Southern 
Japan, and Georgia (U. S. of America). Of this latter flora, 
found chiefly at Oeninghen, in the northern extremity of Switz- 
erland, 465 species are known, of which 166 species are trees 
or shrubs, half of them being evergreens. They comprise se- 
quoyas like the California giant trees, camphor-trees, cinnamons, 
sassafras, bignonias, cassias, gleditschias, tulip-trees, and many 
other American genera, together with maples, ashes, planes, 
oaks, poplars, and other familiar European trees represented 
by a variety of extinct species. If we now go to the west coast 
of Greenland, in 70° X. lat, we find abundant remains of a flora 
of the same general type as that of Oeninghen, but of a more 
northern character. We have a sequoya identical with one of 
the species founcl at Oeninghen, a chestnut, salisburia, liquid- 
ambar, and sassafras, and even a magnolia. We have also seven 
species of oaks, two planes, two vines, three beeches, four pop- 
lars, two willows, a walnut, a plum, and several shrubs sup- 
posed to be evergreens — altogether 137 species, mostly well and 
abundantly preserved ! 

But even farther north, in Spitzbergen, in 78° and 79° N. lat., 
and one of the most barren and inhospitable regions on the 
globe, an almost equally rich fossil flora has been discovered, in- 
cluding several of the Greenland species, and othere peculiar, but 
mostly of the same genera. There seem to be no evergreens 
here except coniferae, one of which is identical with the swamp- 
cypress (Taxodlmn distichum) now found living in the Southern 
United States! There are also eleven pines, two Libocedrus, 
two sequoyas, with oaks, poplars, birches, planes, limes, a hazel, 
an ash, and a walnut; also water-lilies, pond-weeds, and an iris 
— altogether about a hundred species of flowering plants. Even 
in Grinnell I^md, within eight and a quarter degrees of the 
pole, a similar flora existed, twenty-flve species of fossil plants 
having been collected by the last arctic expedition, of which 
eighteen were identical with the species from other arctic local- 
ities. This flora comprised poplars, birches, hazels, elms, vibur- 
nums, and eight species of conifers, including the swamp-cypress, 
and the Norway spruce {Pinus alies) which does not now extend 
beyond 69i° X. lat. 



ISLAND USE. 



[V*mL 



Fossil plants closely resembling those just mentioned have 
been fonnd at many other arctic localities, eepeeially in Iceland, 
on tho Mackenzie Eiver in 65° N. lat., and in Alaska. As an 
intermediate station we have, in the neighborhood of Dantzie, 
in lat. 55° N., a Gimilar flora, with the swamp-cypress, sequoyas, 
oaks, poplars, and some cinnamons, laurels, and figs. A little 
farther south, near Breslan, north of the Carpathians, a rich flora 
haa been fonnd allied to that of Oeninghen, but wanting in some 
of the more tropical forms. Again, in the Isle of Mull, in Scot- 
land, in about 56^° N. lat. a plant-bed has been discovered con- 
taining a hazel, a plane, and a sequoya, apparently identical with 
a Swiss Miocene species. 

We thus find one weli-markod type of vegetation spread from 
Switzerland and Vienna to North Germany. Scotland, Iceland, 
Greenland, Alaska, and Spitzbergen, some few of tlie species 
even ranging over tho extremes of latitude between Oeninghen 
and Spitzbergen ; but the great majority being diatiuet, and ex- 
hibiting decided indications of a decrease of temperature aecoi-d- 
ing to latitude, though much less in amount tlian now exists. 
Some writers have thought that the great similarity of the fiorns 
of Greenland and Oeninghen is a proof that they wore not con- 
temporaneous, bnt successive; and that of Greenland has been 
Bupposed to be as old as the Eocene. But the arguments yet 
adduced do not seem to prove sneh a difference of age, because 
there is only that amount of specific and generic diversity be- 
tween the two which might be produced by distance and differ- 
ence of temporatnrc, under the exceptionally equable climate of 
the period. We have even now examples of an equally wide 
range of well-marked types; as in temperate South AmerJon, 
where many of tiio genera and some of the species range from 
the Strait of Magellan to Valparaiso — places differing as mnch 
in latitude as Switzerland and West Greenland; and the same 
may be said of North Australia and Tasmania, where, at a greater 
latitudinal distance apart, closely allied forms of Eucalyptus, 
Acacia, Casnarina, Stylidium. Goodonia, and many other genera 
would certainly form n prominent feature in any fossil flora now 
being preserved. 

Milil Arcitc Climaks of the CiriacfoUB I'tTiod. — In the Upper 



Chap. TX.] MILD ARCTIC CLIMATES. 177 

Cretaceous deposits of Greenland (in a locality not far from those 
of the Miocene age last described) another remarkable flora has 
been discovered, agreeing generally with that of Europe and 
North America of the same geological age. Sixty-five species 
of plants have been identified, of which there are fifteen ferns, 
two cycads, eleven conifei'se, three monocotyledons, and thirty- 
four dicotyledons. One of the ferns is a tree-fern with thick 
stems, which has also been found in the Upper Greensand of 
England. Among the conifers the giant sequoyas are found, 
and among the dicotyledons the genera Populus, Myrica, Ficus, 
Sassafras, Andromeda, Diospyros, Myrsine, Panax, as well as mag- 
nolias, myrtles, and leguminosae. Several of these groups occur 
also in the much richer deposits of the same age in North Amer- 
ica and Central Europe; but all of them evidently afford such 
fragmentary records of the actual flora of the period that it is 
impossible to say that any genus found in one locality was ab- 
sent from the other merely because it has not yet been found 
there. On the whole, there seems to be less difference between 
the floras of arctic and temperate latitudes in Upper Cretaceous 
than in Miocene times. 

In the same locality in Greenland (70° 33' N. lat. and 52° W. 
long.), and also in Spitzbcrgen, a more ancient flora, of Lower 
Cretaceous age, has been found; but it differs widely from the 
other in the great abundance of cycads and conifers and the 
scarcity of exogcns, which latter arc represented by a single 
poplar. Of the thirty-eight ferns, fifteen belong to the genus 
Gleichenia, now almost entirely tropical. There are four genera 
of cycads, and three extinct genera of conifers, besides Glypto- 
strobus and Torrcya (now found only in China and California), six 
species of true pines, and five of the genus Sequoya, one of which 
occurs also in Spitzbcrgen. The European deposits of the same 
age closely agree with these in their general character; conifers, 
cycads, and ferns forming the mass of the vegetation, while exo- 
gens are entirely absent, the above-named Greenland poplar be- 
ing the oldest known dicotyledonous plant.* 

' The preceding account is mostly derived from Professor Heer*8 great work '* Flora 
Fossilis Arctica.'* 

12 



178 



ISLA^'D USK. 



£P*btL 



If we take tliese facts as really representing the flora of the 
period, we shsill be forced to condiide that, measured by the 
change effected in its plants, the lapse of time between the Lower 
and Upper Cretaceous deposits was fur greater than between the 
Upper C'retaceoiia and the Miocene — a conclusion quite opposed 
to the indications afforded by the inoihisca and the Iirgher ani- 
mals of the two periods. It seeme probable, therefore, that these 
Lower Cretaceous plants represent local peculiarities of vegeta- 
tion such as now sometimes occur in tropical countries. On 
sandy or coralline islands in the Malay Areliipelago there will 
often be found a vegetation consisting almost wholly of cycads, 
pandani, and palms; while a few miles off, on moderately ele- 
vated land, not a single specimen of either of thfsc families may 
be seen, but a dense forest of dicotyledonous trees covering the 
whole country, A lowland vegetation such as that above de- 
scribed uiiirht be destroyed and its remains preserved by a sjight 
depression, allowing it to be covered np by the detritus of some 
adjacent river; while not only would the subsidence of high 
land ho n less frequent occurrence, but when it did oecnr the 
steep banks would be undermined by the waves, and the trees 
falling down would be floated away, and would either be cast 
on some distant shore, or slowly decay on the surface or in tlio 
depths of the ocean. 

From the remarkable series of facts now briefly summarized, 
we learn that whenever plant-remains have been discovered 
within the arctic regions, either in Tertiary or Cretaeeons de- 
posits, they show that the climate was one capable of support- 
ing a rich vegetation of trees, shrubs, and herbaceous plants, 
similar in general character to that which prarailed in the tem- 
perate zonu at the same periods, but showing the influence of 
A less congenial climate. These deposits belong to at least four 
distinct geological horizons, and have been found widely scat- 
tered within the Arctic Cirelo ; yet nowhere has any proof been 
obtained of intercalated cold periods such as would bo indicated 
by the remains of a stunted vegetation, or a niolluscan fauna 
similar to that which now prevails there. 

Stratiffraphieal Evidence of Zofig-continved Mild Arctic Con- 
diiioHn. — Let us now turn to the stratigraphical evidence, which, 



Chap. IX.] MILD ARCTIC CLIMATES. 179 

as we liave already shown, offers a crucial test of the occurrence 
or non-occurrence of glaciation during any extensive geological 
period ; and here we have the testimony of perhaps the greatest 
living authority on arctic geology — Professor Nordenskjold. In 
his lecture on the " Former Climate of the Polar Regions " he 
says, " The character of the coasts in the arctic regions is es- 
pecially favorable to geological investigations. While the val- 
ley's are, for the most part, tilled with ice, the sides of the moun- 
tains in summer, even in the 80th degree of latitude, and to a 
height of 1000 or 1500 feet above the level of the sea, are 
almost wholly free from snow. Nor are the rocks covered with 
any amount of vegetation worth mentioning, and, moreover, the 
sides of the mountains on the shore itself frequently present 
perpendicular sections which everywhere expose their bare sur- 
faces to the investigator. The knowledge of a mountain's geog- 
nostic character, at which one, in the more southerly countries, 
can only arrive after long and laborious researches, removal of 
soil and the like, is here gained almost at the first glance ; and 
as we have never seen in Spitzbergen nor in Greenland, in these 
sections, often many miles in length, and including, one may say, 
all formations from the Silurian to the Tertiary, any boulders 
even as large as a child's head, there is not the smallest proba- 
bility that strata of any considerable extent containing boulders 
are to be found in the polar tracts previous to the middle of the 
Tertiary period. Since, then, both an examination of the geog- 
nostic condition and an investigation of the fossil flora and 
fauna of the polar lands show no signs of a glacial era having 
existed in those parts before the termination of the Miocene 
period, we are fully justified in rejecting, on the evidence of 
actual observation, the hypotheses founded on purely theoretical 
speculations which assume the many-times-repeated alternation 
of warm and glacial climates between the present time and the 
earliest geological ages." * And again, in his " Sketch of the 
Geology of Spitzbergen," after describing the various forma- 
tions down to the Miocene, he says, " All the fossils found in 
the foregoing strata show that Spitzbergen, during former geo- 

1 Geologioal Magazine, 1875, p. 531. 



180 



ISIAND LIFE. 



[Part I. 



logical ages, enjoyed a magnificent climate, wiiicli, indeed, was 
somewhat colder during tlie Miocene penod, bnt was still favor- 
able for an extraordinarily abundant vegetation, miicli more 
Inxtiriant than that which now occurs even in tlie southern part 
of Scandinavia; and I linve in these strata sought in vain for 
any sign that, as some geologists have of late endeavored to 
render probable, these favorable eliinatie conditions have been 
broken off by intervals of ancient glacial periods. The prolilea 
I have had the opporttinity to examine during my various Spitz- 
bergen expeditions wonld certainly, if laid down on a line, oc- 
cnpy an extent of a thousand EmjUsk miles; and if any former 
glacial period Lad existed in this region there ought to have 
been some trace to be observed of erratic blocks, or other forma- 
tions which dietingnieh glacial action. But this has not been 
the case. In the strata, whose length I have reckoned alone, I 
have not found a single fragment of a foreign rock so large as 
a child's head."' 

Now it is quite impossible to ignore or evade the force of 
this testimony as to the continuous warm climates of the north 
temperate and polar zones throughout Tertiary times. The 
evidence extends over a vast area, both in space and time; it ie 
derived from the work of the most competent living geologists ; 
and it is absolutely consistent in its general tendenej'. We have 
in the Lower Cretaceous period an almost tropical climate in 
France and England, a somewhat lower temperature in the 
United States, and a mild insular climate in the arctic regions. 
In each successive period the climate becomes soEuewhat less 
tropical ; but down to the Upper Miocene it rciimins warm 
temperate in Central Europe, and cold temperate within the 
|H>lar area, with not a trace of any intervening periods of arctic 
cold. It then gradually cools down and merges through the 
Pliocene into the glacial epoch in Europe, while in the arctic 
zone there is a break in tlie record between the Miocene and 
the recent glacial deposits.' 

■ CtiJotiiral Ma-iatint. 18TG. p. SC.G. 

* I( is iiitfli'csling to uWrve tlint llie Crclnceoiis flnra or tlio United Stnics (that 
of (lie Dakritii Bn)U|<) mcltCBItt n (onieHlinl cooler climntc than llinl of ihe fulloning 
Eoi'cni' [leriwl, Mr. Do Rnnce(in llie b«'I"8'''«I rippemlix lo rnpinin SirG. Nnre»9 



Chap. IX.] MILD AHCTIC CLIMATES. 181 

Accepting this as a substantially correct account of the gen- 
eral climatic aspect of the Tertiary period in the Northern Hem- 
isphere, let us SCO whether the principles we have already laid 
down will enable us to give a satisfactory explanation of its 
causes. 

The Causes of Mild Arctic Climates, — In his remarkable 
series of papers on " Ocean Currents," Dr. James CroU has 
proved, with a wealth of argument and illustration whose co- 
gency is irresistible, that the very habitability of our globe is 
duo to the equalizing climatic effects of the waters of the ocean ; 
and that it is to the same cause that we owe, either directly or 
indirectly, almost all the chief diversities of climate between 
places situated in the same latitude. Owing to the peculiar dis- 
tribution of land and sea upon the globe, more than its fair pro- 
portion of the warm equatorial waters is directed towards the 
western shores of Europe, the result being that the British Isles, 
Norwa}', and Spitzbergen have all a milder climate than any 
other parts of the globe in corresponding latitudes. A very 
small portion of the arctic regions, however, obtains this bene- 
fit, and it thus remains, generally speaking, a land of snow and 
ice, with too short a summer to nourish more than a very scanty 
and fugitive vegetation. The only other opening than that be- 
tween Iceland and Britain by which warm water penetrates 
within the Arctic Circle is tlirough Behring Strait ; but this 
is both shallow and limited in width, and the consequence is 
that the larger part of the warm currents of the Pacific turns 
back along the shores of the Aleutian Islands and Northwest 
America, while a very small quantity entei*s the icy ocean. 

But if there were other and wider openings into the Arctic 
Ocean, a vast quantity of the heated water which is now turned 

** Narrative of u Voyage to the Polar Sea **) remarks as follows : ** In the overlying 
American Kocenes occur types of plants occurring in the European Miocenes and 
still living, proving the truth of Trufessor I^esquereux^s postulate, that the plant 
types appear in America a stage in advance of their advent in Europe. These plants 
point to a far higher mean temperature than those of the Dakota group, to a dense 
atmosphere of vapor, and a luxuriance of ferns and palms.** This is very important 
as adding further proof to the view that the climates of former periods are not due 
to any general refrigeration, bnt to causes which were subject to change and alterna- 
tion in former ages as now. 



183 



ISLAND LIFE. 



[P*j«T I. 



backward would entoi- it, and would produce an amelioration of 
tiio (■liiiiate of wliieli we ean hardly form a conception. A great 
amelioratiou of climate would also be caused hy the breakiiig- 
up or the lowering of such arctic highlands as now favor the 
accuuinlntion of ice; while the in terpen etration of the sea into 
any part of the great continents in the tropical or temperate zones 
would again tend to raise ^he winter temperature, and render 
any long continuance of snow in their vicinity almost impossible. 

Now geologists have proved, quite independently of any sneh 
questions as we are Iiere discussing, that changes of the very 
kinds above referred to have occurred during the Tertiary 
period ; and that there has been, Ejieaking broadly, a steady 
change from a comparatively fragmentary and ingular condition 
of the great north temperate land3 in early Tertiary times to 
that more compact and continental condition which now pre- 
vails. It is, no doubt, diHioult and often impossible to deter- 
miue liow long any ]Kirticnlar geograi)hical condition lasted, or 
whether the changes in one country were exactly coincident 
with those in another; but it will be sufficient for our purpose 
briefly to indicate those more important changes of hind and 
sea during the Tertiary period which must have produced r 
decided effect on the climate of the Northern nemisphere. 

Gnoyraphtcal Chamjes Favoring Mild JVorthcrii- Vlimafea in 
Tertiary Times. — The distribution of the Eocene and Miocene 
formations shows that during a considerable portion of the 
Tertiary period an inland sea, more or less occupied by an 
archipelago of islands, extended across Central Europe between 
the Baltic and the Black and Caspian seas, and thence by nar- 
rower channels southeastward to the valley of the Enphrates 
and the Persian Gulf, thus opening a cominnnication between 
the North Atlantic and the Indian Ocean. From the Caspian 
also a wide arm of the sea extended dnring some part of the 
Tertiary epoch nortliward to the Arctic Ocean, and there is 
nothing to show that this sea may not have been in existence 
during the whole Tertiary period. Another channel probably 
existed over Egypt' into the eastern basin of the Mediterranean 

' Mr. S. R. J. Rkenclilc)- infDrros me ilml lie li. 
■1c]iosiu, coDMsling of dnya und anliyiiruii!: f^,\<w 



Chap. IX.] MILD ARCTIC CLIMATES. 183 

and the Black Sea ; while it is probable that there was a eom- 
munication between the Baltic and the White Sea, leaving 
Scandinavia as an extensive island. Turning to India, we find 
tliat an arm of tlio sea of gi*eat width and depth extended from 
the Bay of Bengal to the mouths of the Indus ; while the enor- 
mous depression indicated by the presence of marine fossils of 
Eocene age at a height of 16,500 feet in Western Thibet renders 
it not improbable that a more direcl channel across Afghanistan 
may have opened a communication between the West Asiatic 
and Polar seas. 

It may be said tliat the changes here indicated are not war- 
ranted by an actual knowledge of continuous Tertiary deposits 
over the situations of tlie alleged marine channels ; but it is no 
less certain that the seas in which any particular strata were de- 
posited were always more extensive than the fragments of tliose 
strata now existing, and often immensely more extensive. The 
Eocene deposits of Europe, for example, have certainly under- 
gone enormous denudation, both marine and subaerial, and may 
have once covered areas where we now find older deposits (as 
the chalk once covered the weald), while they certainly exist 
concealed under some Miocene, Pliocene, or recent beds. We 
find them widely scattered over Europe and Asia, and often 
elevated into lofty mountain-ranges; and we should certainly 
err far more seriously in confining the Eocene seas to the exact 
areas where we now find Eocene rocks than in liberally extend- 
ing them so as to connect the several detached portions of the 
formation whenever there is no valid argument against our 
doing so. Considering, then, that some one or more of the sea- 
communications here indicated almost certainly existed during 
Eocene and Miocene times, let us endeavor to estimate the prob- 
able effect such communications would have upon the climate 
of the Northern Hemisphere. 

Hie Indian Ocean as a Source of Heat in Tertiary Times, — 
If we compare the Indian Ocean with the South Atlantic, we 
shall see that the position and outline of the former are both 



Kgypt nnd Niibin, nt a height of about GOO feet nbove the sea-level ; but these may 
have been of fresh-wnter origin. 



very favorable for the aeciiimilation of a large body of warm 
water moving northward. Its eoiithern opening between 
South Africa and Australia is very wide, and the tendency of 
the trade-winds would be to coneentrato the currents towai-da 
its nortiiwestern extremity, just where tlie two great channels 
above described formed an outlet to the nortliern eeas. As will 
be shown in onr nineteenth chapter, there were probably, during 
the earlier portion of the Tertiary period at least, several large 
islands in the space between Madagascar and South India ; but 
these had wide and deep channels between them, and their effect 
would probably have been favorable to the conveyance of heat- 
ed water northward by concentrating the currents, and thus 
producing mnssive bodies of moving water analogous to the 
Gulf Stream of the Atlantic' Less heat would thus be lost by 
evaporation and radiation in the tropical zone, and an impulse 
would be acquired which would carry the warm water into the 
north polar area. About the same period Australia was divided 
into two islands, separated by a wide channel in a north and 
south direction (seo Chapter XXII.), and through tins another 
current would almost certainly set northward, and be directed 
to the northwest by tlie southern extension of Malayan Asia. 
The more insular condition at thi>! period of Australia, India, 
and North Africa, with the depression and probable fertility of 
the Central Asiatic plateau, would lead to the Indian Ocean 
being traversed by regular trade-wintls instead of by variable 
monsoons, and thus the constant vis a tergo, which is so efficient 
in the Atlantic, wonld keep up a steady and powerful current 
towards tlie nortliern parts of liie Indian Ocean, and thence 
through the midst of the European archipelago to the northern 
ecas. 

Now it is quits certain that audi a condition as we have here 
sketched out would produce a wonderful effect on the climate 
of Central Kurope and Western and Northern Asia. Owing to 
the warm currents being concentrated in inland seas, instead of 

' Ry rcrurring to 0111 mnp of ilio Indinn Occnn »\\a\\ mg tlio Biibmnrino ^nnks in- 
dicnliiig oiicioiil islnnds (Clinp. XIX,), U will be oriilwil llini ilio Eoutlienat tmJ«- 
wincli, ihcit cxc!«plionn1lf ponetriil, wonlil c«iis« a roit boJj of wiler la enter tbe 
<]cc]i Ai'nblaii Se*. 



Chap. IX.] MILD ARCTIC CLIMATES. 185 

being dispersed over a wide ocean like tlio North Atlantic, 
much more heat would be conveyed into the Arctic Ocean, and 
this would altogether prevent the formation of ice on the 
northern sliores of Asia, which continent did not then extend 
nearly so far north and was probably deeply interpenetrated by 
the sea. This open ocean to the north, and the warm currents 
along all the northern lands, would so equalize temperature that 
even the northern parts of Europe might then have enjoyed a 
climate fully equal to that of the warmer parts of New Zealand 
at the present day, and might have well supported the luxuriant 
vegetation of the Miocene period, even without any help from 
similar changes in tlie Western Hemisphere.' 

Condition of North America during the Tertiary Period. — 
But changes of a somewhat similar character have also taken 
place in America and the Pacific. An enormous area west of 
the Mississippi, extending over much of the Rocky Mountains, 
consists of marine Cretaceous beds 10,000 feet thick, indicating 
great and long-continued subsidence, and an insular condition 
of Western America with a sea probably extending northward 
to the Arctic Ocean. As marine Tertiary deposits are found 
conformably overlying these Cretaceous strata. Professor Dana 
is of opinion that the great elevation of this part of America 
did not begin till early Tertiary times. Other Tertiary beds in 
California, Alaska, Kamtschatka, the Mackenzie River, the Parry 
Islands, and Greenland indicate partial submergence of all these 
lands with the possible influx of warm water from the Pacific ; 

* In his recently published " r..ectures on Physicnl Geogrnphy," Professor Hnughton 
onlcuhites that more than iialf the solar heat of the torrid zone is carried to the 
temperate zones by ocean cnrrents. 'J*he Gulf Stream itself carries one twelfth of 
the total amount, but it is probable that a very tmsnll fraction of this quantity of heat 
reaches the polar seas, owing to the wide area over which the current spreads in the 
North Atlantic. The corresponding stream of the Indian Ocean in Miocene times 
would have been fully equal to the Gulf Stream in heating power, while, owing to its 
being so much more concentrated, a large proportion of its heat may have reached 
the polar area. But the Arctic Ocean occupies less than one tenth of the area of 
the tropical seas ; so that whatever proportion of the heat of the tropical zone was 
conveyed to it would, by being concentrated into one tenth of the surface, produce 
an enormously increased effect. Taking this into consideration, we can hardly doubt 
that the opening of a sufficient passage from the Indian Ocean to the arctic seas 
would produce the effects above indicated. 



ISLAND LIFE. 



[P« 



and the conBiderable elevation of some of the Miocene beds in 
Greenland and Spitzbergen renders it prabable that theae coun- 
tries were then niucb lesa elevated, in ivliicli case only their 
higher summits would bo covered with porpetnal snow, and no 
glacicra would descend to the eea. 

In the Pacific there was probably an elevation of land eonn- 
terbalancing, to some extent, the great depression of so much of 
the noi-tliern continents. Our map in Chapter XV. shows the 
islands that would be produced by an elevation of the great 
shoals nnder a thousand fathoms deep, and it is seen that these 
all trend in a southeast and northwest direction, and would thus 
facilitate the production of definite currents inipollcd by the 
southeast trades towards the Northwest Pacific, where they wonld 
gain access to tlic polar seas through Behring Strait, which was, 
perhaps, sometimes both wider and deeper than at present. 

Eff'-d of these Changes on the Cliviate of the Arctic Eeffions. 
— These varions clianges of sea and land, all tending towards a 
transferrenco of heat from the equator to the north teniperato 
zone, were not improbably still further angmented by the exist- 
ence of a great inland South American sea occupying what are 
now the extensive valleys of the Amazon and Orinoco, and form- 
ing an additional reservoir of superheated water to add to the 
supply poured into the North Atlantic. 

It is not, of course, supposed that all the modifications hero in- 
dicated coexisted at the same time. We have good reason lo 
believe, fi-om the known distribution of animals in tlie Tertiary 
period, that land commnnications have at times existed between 
Europe or Asia and North America, cither by way of Behring 
Strait, or by Iceland, Greenland, aud Jjibrador. But the same 
e%'idence shows that these land communications wera the excep- 
tion rather than the rule, and that they occurred only at long in- 
tervals and for short periods, so as at no time to bring about any- 
thing like a complete interchange of the productions of the two 
continents.' We may therefore admit that the communication 
between the tropical and arctic oceans was occasionally inter- 

' For Mn nceouni of ihe reMmbl.incos ntid diffuroncea of Ihe mutninoliB of tlie iwo 
cuiitinenta daring )lio Teninry epoch, sic mv " Gengrn|>hicnl Diatribaiion of Ani- 

lnnl«,-Vul. r., ri>. HO. l.-ifi. 



CHAP.IX.J MILD ARCTIC CLIMATES. 187 

rupted in one or other direction ; but if we look at a globe in- 
stead of a Mercator's chart of the world, we shall see that the 
disproportion between the extent of the polar and tropical seas 
is so enormons that a single wide opening, with an adequate im- 
pulse to carry in a considerable stream of warm water, would be 
amply sufficient for the complete abolition of polar snow and 
ice, when aided by the absence of any great areas of high land 
wuthin the polar circle, such high land being, as we have seen, 
essential to the production of perpetual snow even at the pres- 
ent time. 

Those who wish to understand the effect of oceanic currents 
in conveying heat to the north temperate and polar regions 
should study the papers of Dr. Croll already referred to. But 
the same thing is equally well shown by the facts of the actual 
distribution of heat due to the Gulf Stream. The difference 
between tlie mean annual temperatures of the opposite coasts of 
Europe and America is well known and has been already quoted ; 
but the difference of their mean winter temperature is still more 
striking, and it is this which concerns us as more especially af- 
fecting the distribution of vegetable and animal life. Our mean 
winter temperature in the "West of England is the same as that 
of the Southern United States, as well as that of Shanghai in 
China, both about twenty degrees of latitude farther south ; and 
as we go northward the difference increases, so that the winter 
climate of Nova Scotia in lat. 45*^ is found within the Arctic 
Circle on the coast of Norway ; and if the latter country did 
not consist almost wholly of precipitous snow-clad mountains, it 
would be capable of supporting most of the vegetable products 
of the American coast in tlie latitude of Bordeaux.* 

With these astounding facts before us, due wholly to the 
tranferrence of a portion of the warm currents of the Atlantic 
to the shores of Europe, even with all the disadvantages of an 
icy sea to the northeast and ice-covered Greenland to the north- 

' Professor Ilnughton lins mndc an elnbomte cnlculntion of the difference between 
existing climates and those of Miocene times, for all the places where a Miocene flora 
has been discovered, by means of the actual range of corresponding species and gen- 
era of plants. Although this method is open to the objection that the ranges of 
plants and aiiimnlii arc not determined by temperature only, yet the results may be 



188 

west, how can we donbt tlic enonnoiisly greater effect of siicli n 
condition of tliiugs as lias been' shown to liave existed during 
the Tertiary epoch i Instead of oa^ great stream of warm water 
spreading widely over the North Atlantic and thus hisiiig the 
greater part of its stiire of heat before it reaches the arctic sens, 
we should have several etreams conveying the heat of far more 
extensive tropical oceans l>y conipavatively narrow inland chan- 
nels, thus being able to transfer a large proportion of their heat 
inlo the nortliern and arctic seas. Tlie heat that they gave out 
during the passage, instead of being widely dispersed by winds 
and much of it lost in the higher atmosphere, would directly 
ameliorate the climate of the continents they passed through, 
and prevent all accumulation of snow except on the loftiest 
mountains. The formation of ice in tlie arctic seas would then 
be impossible; and the mild winter climate of the latitude of 
North Carolina, which, by the Gulf Stream, is ti-ansferred 20' 
nortliward to our islands, might certainly, under the favorable 
conditions which prevailed during the Cretaceous, Eocene, and 
Miocene periods, have been carried another 30" north to Green- 
land and Spitzbergen; and this would bring about exactly the 
climate indicated by the fossil arctic vegetation. For it must 
be remembered that the arctic summers are, even now, really 
hotter than ours; and if the winter's cold were abolished and all 

np[>roxininlet}' correct, nnd nre ver; interesling. Tlie rullowing tnble, nliicli eiimma.- 
rixBS llieie reaulu.u tuken from liii "Lecturm on I'h^Elual Geogrnphv," p. Stii 



1 1„«,..» 


Pre«i.l 


TemperniLrf. 


DilTercDM. 




Ifc-.'.SO 

on'.oo 

70MK) 

Te'-.oo 


85°.e 

VJ'A 


Cft^.B F. 
62'. fi 
4M'.2 

i-i'-'.a 


Ifi°.2 F. 

ns°.o 

3G°0 
3.-.°. 3 
4<°.0 


2. Danwic 

3. Icdnnd: 

4. Mnckeiiiia Blvor 

n. Disco (Greentmid) 

e. Spiishergon 

7. Grinnell I.niid 



ft is intBrCBtine lo note ilini Icclniid. wliicli is noir exposed to ili« full influence of 
the Gulf SlrentD.vrnaonl)' IS^C F. wnrtner in Miocene Iiine« ; while Mnakenalcltiver, 
now totiilly removed fioni its influence, wns 28^ wnrmer. Tlii«, ns well nn (lie greiiler 
increate of lempernluro at we go nonhnard and Ihe point nroe becomes more limited, 
is qniie in nccoi'dniice nilti tlie view of llie cnuses which broughl about Ihe Miocene 
rlimaie which is liei-c ndvociitcd. 



Chap. IX.] MILD ARCTIC CLIMATES. 189 

ice-accnmulation prevented, the high nortliern lands would be 
able to support a far more luxuriant summer vegetation than is 
possible in our unequal and cloudy climate.* 

Effect of High Eccentricity on the Warm Polar Climates, — 
If the explanation of the cause of tlie glacial epoch given in the 
last chapter is a correct one, it will, I believe, follow that changes 
in the amount of eccentricity will produce no important altera- 
tion of the climates of the temperate and arctic zones so long 
as favorable geographical conditions, such as have been now 
sketched out, render the accumulation of ice impossible. The 
effect of a high eccentricity in producing a glacial epoch was 
shown to be due to the capacity of snow and ice for storing up 
cold, and its singular power (when in large masses) of preserving 
itself unmelted under a hot sun by itself causing the interposi- 
tion of a protective covering of cloud and vapor. But mobile 
currents of warm water have no such power of accumulating and 
storing up heat or cold from one year to another, though they 
do in a pve-eminent degree possess the power of equalizing the 
temperature of winter and summer, and of conveying the super- 
abundant heat of the tropics to ameliorate the rigor of the arc- 
tic winters. However great was the difference between the 
amount of heat received from the sun in winter and summer in 
the arctic zone during a period of high eccentricity and winter 
in aphelion, the inequality would be greatly diminished by the 
free ingress of warm currents to the polar area ; and if this was 

' Tiic objection has been made that the long polar night would of itself be fiital 
to the existence of such a luxuriant vegetation as we know to have existed ns far as 
80^ N. lat., nnd that there must have been some alteration of the position of the pole, 
or diminution of the obliquity of the ecliptic, to permit such plants as magnolias and 
large-leaved maples to flourish. But there appear to be really no valid grounds for 
such an objection. Not only are numbers of Alpine and arctic evergreens deeply 
buried in the snow for many months without injury, but a variety of tropical and sub- 
tropical plants are preserved in the hot-houses of St. Petersburg and other northern 
cities which are closely matted during winter, and are thus exposed to as much 
darkness as the night of the arctic regions. We have, besides, no proof that any of 
the arctic trees or large shrubs were evergreens, and the darkness would ceitninly not 
be prejudicial to deciduous plants. Willi a suitable temperature there is nothing to 
prevent a luxuriant vegetation up to the pole, and the long-continued day is known 
to be highly favorable to the development of foliage, which in the same species is 
larger and better developed in Norway than in the South of England. 



ISLAND UXE. 



[F*nL 



sufficient to j)reveiit any accumnlntion of ice, tlie Biimmers would 
be warmeil to tlie full extent of the powers of tlie aim dnring 
the long polar day, wliich is such «s to give the pole at midsum- 
mer more heat diiniig tlie t wen tj-- four hours than the equator 
receives during its day of twelve hours. The only difference, 
then, that would he directly produced by the clianges of eccen- 
tricity and precession would he that the eummera woidd he Rt 
one period almost tropical, at the other of a more mild and uni- 
form temperate character; while the winters would be at one 
time somewhat longer and colder, but never, prolinbly, more 
severe than they are now in the West of Scotland. 

But though Ligh eccentricity would not directly modify the 
mild climates produced hy the state of the Northern Hemisphere 
which prevailed during Cretaceous, Eocene, and Miocene times, 
it might indirectly affect it hy increasing the mass of antarctic 
icG, and thus increasing the force of the trade-winds and the re- 
sulting north ward- flowing warm currents. Now there are many 
peculiarities in the distribution of plants and of eomo groups of 
animals in the Southern Hemisphere which render it almost cer- 
tain that there has sometimes been a greater exteusiou of the 
nutarctic lands during Tertiary times; and it is therefore not 
improbable that a more or less glaciated condition may have been 
a long-persistent feature of the Southern Hemisphere, due to the 
peculiar distribution of land and eea which favoi-s the production 
of ice-fields and glaciers. And as we have seen that during Uio 
last three million years the eccentricity has been almost always 
much higher than it is now, we should expect that the quantity 
of ice in the Southern Hemisphere will usually have been great- 
ei', and will thus have tended to increase the force of those oce- 
anic currents which produce the mild climates of the Northern 
Hemisphere. 

Jividencea of Climate In the iSdcandar;/ and Paliporoic £j?och8. 
— We have already seen that so far back as the Creiaceous pe- 
riod tliero is the most conclusive evidence of the prevalence of a 
very mild climate not only in tempemte but also in arctic lands, 
while there is no proof whatever, or even any clear indication, 
of early glacial epochs at nil comparable in extent and severity 
with that which has so recently occurred; and we have seen 



Chap. IX.] MILD ARCTIC CLIMATES. 191 

reason to connect this state of things with a distribution of land 
and sea highly favorable to the transferrence of warm water from 
equatorial to polar latitudes. So far as we can judge by the 
plant-remains of our own country, the climate appears to have 
been almost tropical in the Lower Eocene period ; and as we go 
farther back we find no clear indications of a higher, but often 
of a lower, temperature, though always warmer or more equable 
than our present climate. The abundant corals and reptiles of 
the Oolite and Lias indicate equally tropical conditions; but 
further back, in the Trias, the flora and fauna become poorer, 
and there is nothing incompatible with a climate no warmer 
than that of the Upper Miocene. This poverty is still more 
marked in the Permian formation, and it is here that clear indi- 
cations of ice-action are found in the Lower Permian conglome- 
rates of the West of England. These beds contain abundant 
fragments of various rocks, often angular and sometimes weigh- 
ing half a ton, while others are partially rounded, and have pol- 
ished and striated surfaces, just like the stones of the " till." 
They lie confusedly bedded in a red unstratified marl, and some 
of them can be traced to the Welsh hills from twenty to fifty 
miles distant. This remarkable formation was first pointed out 
as proving a remote glacial period by Professor Ramsay ; and 
Sir Charles Lyell agreed that this is the only possible explana- 
tion that, witli our present knowledge, we can give of them. 

Permian breccias are also found in Ireland, containing blocks 
of Silurian and Old Ked Sandstone rocks, which Professor Hull 
believes could only have been carried by floating ice. Similar 
breccias occur in the South of Scotland, and these are stated to 
be '* overlaid by a deposit of glacial age, so similar to the breccia 
below as to be with difliculty distinguished from it."* 

These numerous physical indications of ice-action over a con- 
siderable area during the same geological period, coinciding with 
just such a poverty of organic remains as might be produced by 
a very cold climate, are very important, and seem clearly to in- 
dicate that at this remote period geographical conditions were 
such as to bring about a glacial epoch in our part of the world. 

* Geological Magaanne^ 1S73, p. 320. 



Ida 



ISLAND LIFE. 



[F«n-I. 



Boulder-beds nlso occur in the Carboniferous formation, both 
in Scotland, on tlic continent of Europe, and in Nortli America ; 
and Professor Dawson considei*s tbat he has detected true glacial 
deposits of ttie same ago in Nova Scotia. Boulder-bods also oc- 
cur in ilio Silurian rocks of Scotland and North America, and, 
according to Professor Dawson, even in the Hiironian, older than 
onr Cambrian. None of tlieee indications are, however, so eatie- 
factory as those of Permian age, where we have the very kind 
of evidence wo looked for in vain throughout the whole of the 
Tertiary and Secondary periods. Its presence in several locali- 
ties in eueh ancient rocks as the Permian is not only most im- 
portant as indicating a glacial epoch of some kind in Palieozoio 
times, but confirms us in the validity of our conchision that the 
total' absence of any such evidence thronghout the Tertiary and 
Secondary epochs demonstrates the absence of recurnng glacial 
epochs in the Northern Hemisphere, notwithstanding the fre- 
quent recnrrence of periods of high eccentricity. 

Warm Arctic Vlimaifs In Early Secondary and Palimsoic 
TVni^A— The evidence we have already adduced of the mild cli- 
mates prevailing in the arctic regions thi-oughout the Miocene, 
Eocene, and Cretaceous periods is supplemented by a considera- 
ble body nf facts relating to still oai'lier epochs. 

In the Jurassic period, for example, we have proofs of a mild 
arctic climate in the abundant plant-remains of East Siberia 
and Amoorland. with less pro<lnctive deposits in Spitzbergen, and 
at Andueu in Norway, just within the Arctic Circle. But oven 
more remarkable are the marine remains found in many places 
in high northern latitudes, among which we may especially men- 
tion the numerous ammonites and the vertebne of huge reptiles 
of the genera Ichthyosaurus and Tcleosaurua found in the Ju- 
rassic deposits of the Parry Islands, in 77° N. iat. 

In the still earlier Tn'assic age, nautili and ammonites inhab- 
ited the seas of Spitzbergen, where their fossil remains are now 
found. 

In the Carboniferous formation we again meet with plant-ro- 
mains and liede of true coal in the arctic regions. Lcpidodeu- 
droris and Onlamites, together with large spreading ferns, are 
found at Spitzbergen, and at Bear Island, in the extreme north 



Chap. IX.] GEOLOGICAL CLIMATES. 193 

of Eastern Siberia ; while marine deposits of the same age con- 
tain abundance of large stony corals. 

Lastly, the ancient Silurian limestones, which are widely 
spread in the high arctic regions, contain abundance of corals 
and cephalopodous mollusca resembling those from the same de- 
posits in more temperate lands. 

Canclimons as to the Climates of Tertiary and Secondary 
Periods, — If now we look at the whole series of geological facts 
as to the animal and vegetable productions of the arctic regions 
in past ages, it is certainly difficult to avoid the conclusion that 
they indicate a climate of a uniformly temperate or warm char- 
acter. Whether in Miocene, Upper or Lower Cretaceous, Ju- 
rassic, Triassic, Carboniferous, or Silurian times, and in all the 
numerous localities extending over more than half the polar re- 
gions, we find one uniform climatic aspect in the fossils. This 
is quite inconsistent with the theory of alternate cold and mild 
epochs during phases of high eccentricity, and persistent cold 
epochs when the eccentricity was as low as it is now, or lower, 
for that would imply that the duration of cold conditions was 
greater than that of warm. Why, then, should the fauna and 
flora of the cold epochs never be preserved ? Mollusca and many 
other forms of life are abundant in the arctic seas, and there is 
often a luxuriant dwarf woody vegetation on the land, yet in no 
one case has a single example of such a fauna or flora been dis- 
covered of a date anterior to the last glacial epoch. And this 
argument is very much strengthened when we remember that 
an exactly analogous series of facts is found over all the temper- 
ate zones. Everywhere we have abundant floras and faunas in- 
dicating warmer conditions than such as now prevail, but never 
in a single instance one which as clearly indicates colder condi- 
tions. The fact that drift with arctic shells was deposited dur- 
ing the last glacial epoch, as well as gravels and crag with the 
remains of arctic animals and plants, shows us that there is noth- 
ing to prevent such deposits being formed in cold as well as in 
warm periods; and it is quite impossible to believe that in every 
place and at all epochs all records of the former have been de- 
stroyed, while in a considerable number of instances those of 
the latter have been preserved. When to this uniform testimo- 

13 



t94 



ISLAND LIFE. 



tPiiwrl. 



ny of the pal iEon to logical evidence we add the equally uniform 
abeenee of any indication of those icc-bonic rocks, bonldcre, and 
drift whicli are the constant and necessary accompnnimont of 
every period of glaciation, and wliich must inevitably pervade 
all the marine deposits foruied over a wide area so long as the 
state of glaciation continues, we are driven to the conclusion 
that the last glacial epoch of the Northern lleinispliei-a was ex- 
ceptional, and was not preceded by numerous similar glacial 
epochs throughout Tertiary and Secondary time. 

But, although glacial epochs (with the one or two exceptions 
already referred to) were certainly abscTit, considerable changes 
of chmate may have frequently occuri-edjand these would lead 
to important changes in the organic world. We can hardly 
doubt that some such change occurred between the Lower and 
Upper Cretaceous periods, the floras of which exhibit such an 
extraordinary contrast iu general character. We have also the 
testimony of Mr. J. S. Gardner, who has long worked at the fos- 
sil floras of tlie Tertiary deposits, and who states tliat there is 
strong negative and some positive evidence of alternating warm- 
er and colder conditions, not glacial, contained not only in Eng- 
lish Eocene, but all Tertiary beds thi-onghout the world.' In 
the case of marine faunas it is more difficult to judge, but the 
nnincrous changes in the fossil remains from bed to bed, only a 
few feet and sometimes a few inches apart, may be pometimee 
due to change of climate; and when it is recognized that such 
changes have probably occurred at all geological epochs, and 
their effects ai'e systematically searched for, many peculiarities 
in the distribution of organisms through the different members 
of one deposit may be traced to this cause. 

Oeneral View of Oeolor/lcal Climates as Dependent on the 
Pkysk-ul Features of i/ie EartJis Surfaae. — In the preceding 
chapters I have earnestly endeavored to arrive at an explanation 
of geological climates in the temperate and arctic zones which 
should be in harmony with the great body of geological facts 
now available for their elucidation. If my conclusions as here 
set forth diverge considerably from those of Dr. Croll, it is not 



' Gtolixjiral Magniiur, 1877, p. 137. 



Chap. IX.] GEOLOGICAL CLIMATES. 195 

from any want of appreciation of his facts and arguments, since 
for many years I have upheld and enforced his views to the best 
of my ability. But a careful re-examination of the wliole ques- 
tion has now convinced me that an error has been made in esti- 
mating the comparative effect of geographical and astronomical 
causes on changes of climate, and that, while the latter have un- 
doubtedly played an important pait in bringing about the glacial 
epoch, it is to the former that the mild climates of the arctic 
regions are almost entirely due. If I have now succeeded in 
approaching to a true solution of this difficult problem, I owe it 
mainly to the study of Dr. CroU's writings, since my theory is 
entirely based on the facts and principles so clearly set forth in 
his admirable papers on " Ocean Currents in Relation to the Dis- 
tribution of Heat over the Globe." Tiie main features of this 
theory, as distinct from that of Dr. Croll, I will now endeavor to 
summarize. 

Looking at the subject broadly, we see that the climatic con- 
dition of the Northern Hemisphere is the result of the peculiar 
distribution of land and water upon the globe ; and the general 
permanence of the position of the continental and oceanic areas 
— which we have shown to be proved by so many distinct lines 
of evidence — is also implied by the general stability of climate 
throughout long geological periods. The land surface of our 
earth appears to have always consisted of three great masses in 
the north temperate zone, narrowing southward, and terminating 
in three comparatively narrow extremities represented by South- 
ern America, South Africa, and Australia. Towards the north 
these masses have approached each other, and have sometimes 
become united, leaving beyond them a considerable area of 
open polar sea. Towards the south they have never been much 
farther prolonged than at present ; but far beyond their extrem- 
ities an extensive mass of land has occupied the south polar 
area. 

This arrangement is such as would cause the Northern Hem- 
isphero to be always (as it is now) warmer than the Southern, 
and this would lead to the preponderance of northward winds 
and ocean currents, and would bring about the concentration of 
the latter in three great streams carrying warmth to the north 



ISlMilli IJF£. 



xU. 



polar regions. Tliese sti-eanis wonld, ns Dr. Croll lifts so well 
sliown, be gi'eatly increased in power by the giaciation of the 
eouth polar land; tiiid whenever any conaiderablo portion of 
this land was elevated, such a condition of giaciation would cer- 
tainly be bronglit about, and woidd be heightened whenever a 
high degree of eccentricity prevailed. 

It appears to he the general opinion of geologists that the 
great continents liavc undergone a process of development fi'ora 
earlier to later times. Profes-sor Duua says, " The North Amer- 
ican continent, which since early time had been graduidly ex- 
panding in cacii direction from the Northern Azoic, eastward, 
westward, and southward, and which, after the Palteozoic, was 
flnished in its rocky foundation, excepting on the borders of the 
Atlantic and Pacitic and the area of the Rocky Houn tains, had 
reached its full expatision at the close of the Tertiary period. 
The progress from the first was uniform and systematic: the 
land waa at all times simple in outline; and its enlargement 
took place with almost the regularity of an exogenous plant." ' 

A similar development undoubtedly took place in the Euro- 
pean area, which waa apparently never so compact and so little 
interpenetrated by the sea as it ia now, while Europe and Asia 
liavc only become united into one unbroken mass since late 
Tertiary times. 

If, however, the greater contincuta have become more com- 
pact and massive from age to tige, and have received tlieir chief 
extensions northward at a comparatively recent period, while 
the antarctic lands had a corresponding but somewhat earlier 
development, we have all the conditions requisite to explain the 
persistence, with slight fluctuations, of warm climates far into 
the north polar area throughout Palajozoic, Mesozoic, and Ter- 
tiary times. At length, during the latter part of the Tertiary 
epoch, a considerable elevation took place, closing up several of 
the water passages to the north, and raising up extensive areas 
in the arctic regions to become the receptacle of enow and ice 
fiehls. This elevation is indicated by the abundance of Miocene 
and the absence of Pliocene deposits in the arctic zoTie, and tlie 

' "Mnmifll of Goolofi.''," H J cJ., p. CiS. 



mtL 



Chap. IX.] GEOLOGICAL CLIMATES. 197 

considerable altitude of mauy Miocene rocks in Europe and 
Nortli America ; and the occurrence at this time of a long- 
continued period of high eccentricity necessarily brought on 
the glacial epoch in the manner already described in our last 
chapter. 

We thus see that the last glacial epoch was the climax of a 
great process of continental development which has been going 
on throughout long geological ages ; and that it was the direct 
consequence of the north temperate and polar land having at- 
tained a great extension and a considerable altitude just at the 
time when a phase of very high eccentricity was coming on. 
Throughout earlier Tertiary and Secondary times an equally 
high eccentricity often occurred, but it never produced a glacial 
epoch, because the north temperate and polar areas had less high 
land, and were more freely open to the influx of warm oceanic 
currents. But wherever great plateaus with lofty mountains 
occurred in the temperate zone a considerable local glaciation 
might be produced, which would be specially intense during 
periods of high eccentricity ; and it is to such causes we must 
impute the indications of ice-action in the vicinity of the Alps 
during tho Tertiary period. The Permian glaciation appears to 
have been more extensive, and it is quite possible that at this 
remote epoch a sufficient mass of high land existed in our area 
and northward towards the pole to have brought on a true 
glacial period comparable with that which has so recently passed 
away. 

Estimate of the Comparative Effects of Geographical and 
Astronomical Causes in Producing Changes of Climate. — It 
appears, then, that while geographical and physical causes alone, 
by their influence on ocean currents, have been the main agents 
in producing the mild climates which for such long periods pre- 
vailed in the arctic regions, the concurrence of astronomical 
causes — high eccentricity with winter in aphelion — was neces- 
sary to the production of the great glacial epoch. If we reject 
this latter agency, we shall be obliged to imagine a concurrence 
of geographical changes at a very recent period of which we 
have no evidence. We must suppose, for example, that a large 
part of the British Isles — Scotland, Ireland, and Wales at all 



. ISI.AND UXR. 



tPuxI, 



events — were siinnltaneonsly elevated so as to bring extensive 
areas above the line of perpetual enow; that about the Eanie 
time Scandinavia, the Alps, and tbe Pyrenees received a similar 
incroaeo of altitude; and that, almost Bimiiltanoonsly, Eastern 
North America, the Sierra Nevada of California, the CaQcaeiie, 
Lebanon, the southern mountains of Spain, the Atlas range, and 
the Himalayas were each some thousands of feet higher thnn 
they are now; for all these mountains present ns with indica- 
tions of a recent extension of their glaciers, in snperficial phe- 
nomena so similar to those which occur in our own country and 
in "Western Enrope that we cannot suppose them to belong to 
a different epoch. Snch a supposition is rendered more difficult 
by the general concurrence of scientific testimony to a partial 
submergence during the glacial epoch, not only in all parts of 
Britain, but in North America, Scandinavia, and, as shown by 
the wide extension of the drift, in Northern Europe ; and when 
to this we add the difficulty of understanding how any probable 
addition to the altitude of our islanda could have brought about 
the extreme amount of glacJation which they certainly under- 
went, and when, further, we know that a phase of very high 
eccentricity did occur at a period which is generally admitted 
to agree well with physical evidence of the time elapsed since 
the eoM passed away, there seems no sufficient reason why such 
an agency should be ignored. 

No doubt a prejudice has been excited against it in the minds 
of many geologists, by its being thought to lead neceamrii'y to 
frequently recurring glacial epochs throughout all geological 
time. But I have liero endeavored to show that this is not a 
nccessai-y consequence of tho theory, because a concurrence of 
favorable geographical conditions is essential to the initiatiou 
of a glaciation, which, when once initiated, has a tendency to 
maintain itself throughout the varying phases of precession 
occurring during a period of high eccentricity. Wlion. how- 
ever, geographical conditions favor warm arctic climates — as it 
has been shown they have done throughout tho larger portion 
of geological time — then cliangca of eccentricity, to however 
great an extent, have no tendency to bring about a state of 
glaciation, because warm oceanic currents have a prepondei'atiug 



Chap. IX.] GEOLOGICAL CLIMATES. 199 

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

The theory as now set forth should commend itself to geolo- 
gists, since it shows the direct dependence of climate on pliysical 
processes which are guided and modified by those changes in the 
earth's surface which geology alone can trace out. It is in per- 
fect accord with the most recent teachings of the science as to 
the gradual and progressive development of the earth's crust 
from the rudimentary formations of the Azoic age, and it lends 
support to the view that no important departure from the great 
lines of elevation and depression originally marked ont on the 
earth's surface have ever taken place. 

It also shows us how important an agent in the production of 
a habitable globe, with comparatively small extremes of climates 
over its whole area, is the great disproportion between the ex- 
tent of the land and the water surfaces. For if these propor- 
tions had been reversed, large areas of land would necessarily 
have been removed from the beneficial influence of aqueous 
currents or moisture-laden winds ; and slight geological changes 
might easily lead to half the land surface becoming covered with 
perpetual snow and ice or being exposed to extremes of summer 
heat and winter cold, of which our water-permeated globe at 
present affords no example. We thus see that what are usually 
regarded as geographical anomalies — the disproportion of land 
and water, the gathering of the land mainly into one hemisphere, 
and the singular arrangement of the land in three great south- 
ward-pointing masses — are really facts of the greatest signifi- 
cance and importance, since it is to these very anomalies that 
the universal spread of vegetation and the adaptability of so 
large a portion of the earth's surface for human habitation are 
directly due. 



ISLASU LIFE. 



Vnrioui Eaiiinnlea ofGralugLcnl Time, — Denuiiation and Deposition of Strain as a 
Ueuure of Time. — Hour to KEtimnla Ihe Tliickneu of tlie Sedimcnuiry Itocks, — 
How 10 Entimnlc tEie Average Itnte of Deposition of tlie Sedimentary Kocks. — 
The liaie of Geological Change probnbl; Greater in very RomotQ Times. — Value of 
the Prcccdins Estimate of Geological Time. — Orennic Modification Dependent on 
Cliitnge of Conditions. — GeogrBjihicBl Miitntions as a Motive Power in Bringing 
about Organic Clmngei. — Climatal Revolutions as an Agent in Producing Organia 
Changes. — Present Condition of tlie EaitU one of Exceptional Sinbility as reganli 
Climnlo. — Date of Loiit Glncinl Epoch, and its Bearing on the MensaremenE of 
Geolugical Time. —Coiicl tiding liemnrks. 

The subjects discussed in the last tliree chapters introduce us 
to a ditBculty wliicli has hitherto been considered a very for- 
midable one^tliat the maxiuiuin age of the habitable cartli, as 
deduced from phj-sical considerations, does not afford siiflicient 
time either for the geological or the organic changes of which 
we have evidence. Geologists continually dwell on the slow- 
iiCBs of the processes of npheaval and subsidence, of denudation 
of the earth's snrface, aud of the formation of new strata ; while 
on the theory of development as expounded by llr. Darwin the 
variation and moditicntion of organic forms is also a very slow 
process, and has usually been considered to i-etjuii'o an even 
longer series of ages than might satisfy the requirements of 
physical geology alone. 

As an indication of the periods usually contemplated by geol- 
ogists, wo may i-efer to Sir Charles Lyell's calculation in the 
tenth edition of his "Principles of Geology" (omitted in later 
editions), by which he arrived at two hundred and forty millions 
of years as having probably elapsed since the Cambrian period 
— a very moderate estimate in the opinion of most geologists. 
This cnleulation was founded on the rate of modification of the 



Chap. X.] THE EARTH'S AGE. 201 

species of mollnsca ; but much more recently Professor Haugli- 
ton has arrived at nearly similar figures from a consideration of 
the rate of formation of rocks and their known maximum thick- 
ness, whence he deduces a maximum of two hundred millions of 
years for the whole duration of geological time as indicated by 
the series of stratified formations.* But in the opinion of all our 
first naturalists and geologists, the period occupied in the forma- 
tion of the known stratified rocks only represents a portion, and 
perhaps a small poi*tion, of geological time. In the last edition 
of the " Origin of Species " (p. 286), Mr. Darwin says, " Conse- 
quently, if the theory be true, it is indisputable that before the 
lowest Cambrian stratum was deposited long periods elapsed — as 
long as, or probably far longer than, the whole interval from 
the Cambrian ago to the present day ; and that during these 
vast periods the world swarmed with living creatures." Pro- 
fessor Iluxley, in his anniversary address to the Geological So- 
ciety in 1870, adduced a number of special cases showing that, 
on the theory of development, almost all the higher forms of 
life must have existed during the Palaeozoic period. Thus, from 
the fact that almost the whole of the Tertiary period has been 
required to convert the ancestral Orohippus into the true horse, 
ho believes that, in order to have time for the much greater 
change of the ancestral Ungulata into the two great odd-toed 
and even-toed divisions (of which change there is no trace even 
among the earliest Eocene mammals), wo should require a large 
portion, if not the whole, of the Mesozoic or Secondary period. 
Another case is funiished by the bats and whales, both of which 
strange modifications of the mammalian type occur perfectly de- 
veloped in the Eocene formation. What countless ages back must 
we then go for the origin of these groups — the whales from some 
ancestral carnivorous animal, and the bats from the insectivora! 
And even then we have to seek for the common origin of car- 
nivora, insectivora, ungulata, and marsupials at a far earlier pe- 
riod ; so that, on the lowest estimate, we must place the origin 
of the mammalia very far back in Palaeozoic times. Similar 
evidence is afforded by reptiles, of which Professor Huxley says, 

» Nature, Vol. XVUI. (July, 1878), p. 268. 



aoa 



ISLAim LIFE. 



[T«tJ. 



" If the vcTj small differences which are observable between the 
crocodiles of the older Secondary formations and those of the 
present day furnish any sort of an approximation towards an 
estimate of the average rate of change among reptiles, it is al- 
most appalling to reflect how far back in Palteozoic times we 
ninst go before we can hope to arrive at that common stock from 
which the crocodiles, lizards, OrnithoBcelida, and /*lesio8auria, 
which had attained so great a development in the Triaseic epoch, 
innst have been derived." Pi'ofessor Ilanisay lias ex]>ressed sim- 
ilar views, derived from a geiieritl study of the whole series of 
geological formations and their contained fossils. He says, speak- 
ing of the abnndaiit, varied, and weli-developed fauna of the 
Cambrian period, "In this earliest known varied life we find 
no evidence of its having lived near the beginning of tlie zoo- 
logical scries. In a broad sense, compared with what must have 
gone before, both biologically and physically, all the phenomena 
connected with this old period seem, to my mind, to be of quite 
a recent description ; and the climates of seas and lands were of 
the very same kind as those the world enjoys at the present 
day." ' 

These opinions, and the facts on which they are founded, are 
so weighty that we can hardly doubt that, if the time since the 
Cambrian epoch is correctly estimated at two hundred millions 
of years, the d.tte of the commencement of life on tlie earth can- 
not bo much less than five hundred millions; while it may not 
improbably have been longer, because the reaction of the organ- 
ism under changes of the environment is believed to have been 
less active in low and simple than in high and comple-ii forms 
of life, and thus the processes of organic development may for 
countless ages have been excessively slow. 

But, according to the physicists, no such periods as are here 
contemplated can be granted. From a consideration of the pos- 
sible sources of the heat of the sun, as well as from calculations 
of the period during which the earth can have been cooling to 
bring about the present rate of increase of temperature as we 



■ *'<>n ihc Com |iHrii live Vnlae drCcrrnin Geological ^ges Considel'ed m 
Geologiciil Time," Procetdingii o/ Iht Rayal Socitiy, 1871, p. 331. 



Chap. X.] THE EARTH'S AGE. 203 

descend beneath the surface, Sir William Thomson concludes 
that the crust of the earth cannot have been solidified much long- 
er than one hundred million years (the maximum possible be- 
ing four hundred millions), and this conclusion is held by Dr. 
CroU and other men of eminence to be almost indisputable.* It 
will therefore be well to consider on what data the calculations 
of geologists have been founded, and how far the views here set 
forth as to frequent changes of climate throughout all geolog- 
ical time may affect the rate of biological change. 

Denudation and Depodtian of Strata as a Measure of Time. 
— The materials of all the stratified rocks of the globe have been 
obtained from the dry land. Every point of the surface is ex- 
posed to the destructive influences of sun and wind, frost, snow, 
and rain, which break up and wear awa}^ the hardest rocks as 
well as the softer deposits, and by means of rivens convey the 
worn material to the sea. The existence of a considerable depth 
of soil over the greater part of the earth's surface ; of vast heaps 
of rocky debris at the foot of every inland cliff; of enormous 
deposits of gravel, sand, and loam ; as well as the shingle, peb- 
bles, sand, or mud of every sea-shore, alike attest the univer- 
sality of this destructive agency. It is no less clearly shown by 
the way in which almost every drop of running water — whether 
in gutter, brooklet, stream, or large river — becomes discolored 
after each heavy rainfall, since the matter which causes this dis- 
coloration must be derived from the surface of the country, must 
always pass from a higher to a lower level, and must ultimately 
reach the sea, unless it is first deposited in some lake, or by the 
overflowing of a river goes to form an alluvial plain. The uni- 
versality of this subaerial denudation, both as regards spac^ and 
time, renders it certain that its cumulative effects must be very 
great; but no attempt seems to have been made to determine 
the magnitude of these effects till Mr. Alfred Tylor, in 1853,* 
pointed out that by measuring the quantity of solid matter 
brought down by rivers (which can be done with considerable 



* Transactions of the Royal Societjf of Edinburgh^ Vol. XXIII., p. 101 ; Quarterly 
Journal of Science^ 1877 (Croll, on the ** Probable Origin and Age of the Sun "). 

* Philosophical Magazine^ April, 1858. 



ao4 



ISLAND LIE-E. 



[7uCTl. 



acetiracy), we may obtnin the amount of lowering of the land 
area, and also the viae of tbe ocean-level, owing to the quantity 
of matter deposited on its floor. A few jeara later Dr. Croll 
applied the eanie method in more detail to an estimate of the 
amount by which the land is lowered in a given period ; and 
the validity of this method has been upheld by Professor Geikie, 
Sir Charles Lyell, and all onr best geologists, as affording a means 
of actually determining with some approach to accuracy the 
time occupied by one importaut phase of geological change. 

The quantity of matter carried away from the land by a river 
is greater than at first sight appears, and is more likely to be 
under- than over-estimated. By taking samples of water near 
tlie month of a river (but above the influence of the tide) at a 
sufficient number of points in its channel and at different depths, 
and repeating this daily or at other short intervals throughout 
the year, it is easy to determine the quantity of solid matter 
Iield in auspcusion and solution; and if corresponding observa- 
tions determine the quantity of water that is discharged, the 
total amount of solid matter brought down annually may be 
calculated. But, besides this, a considerable quantity of sand, 
or even gravel, is carried along the bottom or bed of tlie river, 
and this has rarely been estimated, so thnt the figures hitherto 
obtained are usnally under the real quantities. There is also 
another source of error caused by the quantity of matter the 
river may deposit in lakes or in flooded hinds during its course; 
for this adds to the amount of denudation performed by the 
river, although the matter so deposited does not come down to 
the sea. After a careful examination of all the best records, 
Professor A, Geikie arrives at the following results as to the 
quantity of matter removed by seven rivers from their basins, 
estimated by the number of years required to lower the whole 
surface an average of one foot : 



The MiBbiHirpi ™mov 


eionefootinGOOO 


ThoGnngM 


H3.-.8 


TheUonnsIIo " 


nut 


The Rhono 


1628 


The l>n»ubo 


0848 


The Po 


T29 


The Mill 


472a 



Chap. X.] THE EARTH'S AGE. 205 

Here we see an intelligible relation between the character of 
the river basin and the amount of denudation. The Mississippi 
has a large portion of its basin in an arid country, and its sources 
are either in forest -clad plateaus or in mountains free from 
glaciers and with a scanty rainfall. The Danube flows through 
Eastern Europe, where the rainfall is considerably less than in 
the West, while comparatively few of its tributaries rise among 
the loftiest Alps. The proportionate amounts of denudation be- 
ing, then, what we might expect, and as all are probably under 
rather than over the truth, we may safely take the average of 
them all as representing an amount of denudation which, if not 
true for the whole laud surface of the globe, will certainly be so 
for a very considerable proportion of it. This average is almost 
exactly one foot in three thousand years.' The mean altitude 
of the several continents has been estimated to be as follows: 
Europe, 671 feet; Asia, 1132 feet; Africa, 900 feet; North 
America, 748 feet ; and South America, 1151 feet. At the rate 
of denudation above given, it results that, were no other forces 
at work, Europe would be planed down to the sea-level in about 
two million years ; while, if we take a somewhat slower rate for 
North America, that continent might last about three million 
years.' This also implies that the mean height of these conti- 

' It has usually been the practice to take the amoant of denudation in the Missis- 
sippi yalley, or one foot in six thoasnnd years, as a measure of the rate of denuda- 
tion in Europe, from an idea apparently of being on the "safe side," and of not over- 
estimating the rate of change. But this appears to me a most unphilosopliical mode 
of proceeding, and unworthy of scientific inquiry. What should we think of astron- 
omers if they always took the lowest estimates of planetary or stellar distances, in- 
stead of the mean results of observation, **in order to be on the safe side?'* As if 
error in one direction were any worse than error in another. Yet this is what geolo- 
gists do systematically. Whenever any calculations are made involving the antiquity 
of man, it is those that give the lowest results that are always taken, for no reason 
apparently except that there was, for so long a time, n prejudice, both popular and 
scientific, against the great antiquity of roan ; and now that a means has been found 
of measuring the rate of denudation, they take the slowest rate instead of the mean 
rate, apparently only because there is now a scientific prejudice in fiivor of extremely 
slow geological change. I take the mean of the whole ; and, as this is almost ex- 
actly the same as the mean of the three great European rivers — the lihone, Danube, 
and Po — I cannot believe that this will not be nearer the truth for Europe than tak- 
ing one North American river as the standard. 

' These figures are merely used to give an idea of the rate at which denudation is 



206 



ISLAND LIFE. 



[PamI. 



iients would have Leen double wliat it is now two million and 
three million years ago respectively ; and, as we have no reason 
to suppoBo this to have been the case, we are led to infer the 
constant action of that upheaving force whicli tlie presence of 
sedimentary fonnations even on the highest monntains also 
demonstrates. 

Wo have already discussed the unequal rate of denudation on 
hills, valleys, and lowlands in connection with the evidence of 
remote glacial epochs (p. 104); what we have now to consider 
is, what becomes of all this denuded matter, and how far the 
known rate of denudation affords ns a nieasnre of the rate of 
deposition, and thus gives us some indication of tlie lapse of 
geological time from a comparison of this rate with the observed 
thickness of stratified rocks on the earth's surface. 

lloio to Ultimate tlie Thichnesa of the Sedimentari/ Hocks. — 
The sedimentary rocks, of which the earth's crust is mainly com- 
posed, consist, according to Sir Charles Lyell's classiHcation, of 
fourteen great formations, of which the most ancient is the Lati- 
i-cntinn, and the most recent the Post-tertiary; with thirty im- 
portant subdivisions, each of which again consists of a more or 
less considerable number of distinct beds or strata. Thus, the 
Silurian formation is divided into Upper and Lower Silnriaa, 
each characterized by a distinct set of fossil remains; and the 
Upper Silurian again consists of a large number of separate 
beds, such as the Wenlock Limestone, the Upper Llandovery 
Sandstone, the Lower Llandovery Slates, etc., each usually char- 
acterized by ft difference of mineral composition or mechaQical 
structure as well as by some peculiar fossils. These beds and 
formations vary greatly in extent, both above and beneath the 



Bclunll V going on now ; lint if no elevnwry forces were nt vrovls, ihe rnie of (leonthi- 
tioti would cui'tniiiljr dimiuLili aa iIjb tnoiintaing »era lowered and tlio elope of Ibe 
ground ererywliore rendered 6niter. TliU would follow not onlv from the ditniniihed 
power of min and rirors, but bwniisa the climnle would beromB more iinifbmi, ths 
ninfall probnbly less, nnd no rocLy pcnks would be left lo be frncliireJ nnd liroken np 
b; iho nciion of frosts, Ii ii eerlnin, bowcvar, tlint no conilncnl Iidh ever romoined 
long iiibjecl to tlie influences of ttena Jation alone ; fur, as we hnvo Bccn in our uxth 
clinpMr, elevation and depreuion linve nlirnyi been going on in one pnrt or oilier of 
tb« •urface. 



Chap.X.] the EARTH'S AGE. 207 

surface, and are also of very varioas thicknesses in different lo- 
calities. A thick bed or series of beds often thins out in a 
given direction, and sometimes disappears altogether, so that 
two beds which were respectively above and beneath it may 
come into contact. As an example of this thinning-out, Amer- 
ican geologists adduce the Palaeozoic formations of the Appa- 
lachian Mountains, which have a total thickness of 42,000 feet, 
but as they are traced westward thin out till they become only 
4000 feet in total thickness. In like manner, the Carbonifer- 
ous grits and shales are 1800 feet thick in Yorkshire and Lan- 
cashire, but they thin out southward, so that in Leicestershire 
they are only 3000 feet thick; and similar phenomena occur 
in all strata and in every part of the world. It must be ob- 
served that this thinning-out has nothing to do with denuda- 
tion (wliich acts upon the surface of a country so as to produce 
great irregularities of contour), but is a regular attenuation of 
the layers of rock, due to a deficiency of sediment in certain 
directions at the original formation of the deposit. Owing to 
this thinning-out of stratified rocks, they are, on the whole, of far 
less extent than is usually supposed. When we see a geological 
map showing successive formations following each other in long 
irregular belts across the country (as is well seen in the case of 
the Secondary rocks of England), and a corresponding section 
showing each bed dipping beneath its predecessor, we are apt 
to imagine that beneath the uppermost bed we shall find all the 
others following in succession like the coats of an onion. But 
this is far from being the case, and a remarkable proof of the 
narrow limitation of these formations has been recently obtained 
by a boring at Ware through the Chalk and Ganlt clay, which 
latter immediately rests on the Upper Silurian Wenlock Lime- 
stone, full of characteristic fossils, at a depth of only 800 feet. 
Here we have an enormous gap, showing that none of earlier 
Secondary or late Palaeozoic formations extend to this part of 
England, unless, indeed, they had been all once elevated and 
entirely swept away by denudation.* 

* The follo^iing stAtement of the depths at which the Pnloeozoic formations have 
been reached in various localities in and around London was given by Mr. H. B. 
Woodward in his address to the Norwich Greological Society in 1S79 : 



fi08 ISLAND LIFE. [Past I. 

But if we corsider liow such deposits are now forming, wc 
eliall find tiiat the thinning-out of the beds of each formation, 
and tlicir restriction to irregnlar bands and patches, is exactly 
what we should expect. The enormous cjuantity of sedioient 
continually poured into the eea by rivers gradually subsides to 
the bottom as soou ss the motion of tiie water is checked. All 
the heavier material must be deposited near the shore or in 
those areas over which it is first spread by the tides or currents 
of the ocean ; while only the very tine mud and clay arc carried 
out to considerable distances. Tims all stratified deposits will 
form most quickly near the shores, and will thin out riipidly at 
greater distances, little or none being formed in the depths of 
tlie great oceans. This important fact was demonstrated by tlie 
specimens of sea-bottom examined during the voyage of the 
CliaUenger, all the " shore-depositfi " being usually confined with- 
in a distance of one hundred or one hundred and fifty miles 
from the coast, while the "deep-sea" deposits are either purely 
organic, being formed of the calcareous or siliceous slceletons of 
Globigerime, radiolarians, and Diatomaceip, or are clays formed 
of undissolved portions of these, together with the disintegrated 
or dissolved materials of pumice and volcanic dust, which, being 
very light, are carried by wind or by water over the widest 
oceans. 

From the preceding considerations we shall be better able to 
appreciate the calculations as to the thickness of stratified de- 
posits made by geologists. Professor Ramsay lias calculated 
that the sedimentary rocks of Britain alone have a totjil maxi- 
mum thickness of 72,600 feet ; while Professor Ilaughton, from 
a survey of the whole world, estimates the maximnm thicknesa 

L}erp Wtlh Ihrovyh ike Terliarg and Cretareoui Formatimu. 

Harwich nt 1032 feet I'euclied rnibntiiferoUH Hock. 

Kenliih Tonn "I1U " " Olil Kcd Snndtione. 

ToUenham Conn Koail " 1064 " " Ueronian. 

BlacknaU " 10O4 " " Devonum orOIJ Red Snndstone. 

Ware " flOO " " Silurinn (Weiilock Plialc). 

We thus Rni] that over a wide nrea, extonding from LonJon lo W'ni'o niid Hanrieh, 
the nhola oS Llie rurinnlionB TrDni Ilia OaJJre to the I'enninn nrc wnnliiig, the Creinceoua 
railing on iho CnrbonireroDa or older Pnlnozoic rocki ; nnd tlie inme deficieni^j ex- 
Iciidi nentsa to Belgium, where the TortJsij bods are foitnd rwling on Cnrbonifuwa 
at II dc|>lh ul kfs than 410 feel. 



Chap.X.] TUE EARTH'S AGE. 209 

of the known stratified rocks at 177,200 feet. Now these max- 
immn thicknesses of each deposit will have been produced only 
where the conditions were exceptionally favorable, either in deep 
water near the mouths of great rivers, or in inland seas, or in 
places to which the drainage of extensive countries was con- 
veyed by ocean currents; and this great thickness will necessa- 
rily bo accompanied by a corresponding thinness, or complete 
absence of deposit, elsewhere. IIow far the series of rocks found 
in any extensive area, as Europe or North America, represents 
the wliole series of deposits which have been made there we 
cannot tell ; but there is no reason to think that it is a very in- 
adequate representation of their maximum thickness, though it 
undoubtedly is of their extent and bulk. When we see in how 
many distinct localities patches of the same formation occur, it 
seems improbable that the whole of the deposits formed during 
any one period should have been destroyed, even in such an area 
as Europe, while it is still more improbable that they should be 
so destroyed over the whole world ; and if any considerable por- 
tion of them is left, that portion may give a fair idea of their 
average, or even of their maximum, thickness. In his admira- 
ble paper on " The Mean Thickness of the Sedimentary Rocks," * 
Dr. James CroU has dwelt on the extent of denudation in di- 
minishing the mean thickness of the rocks that have been 
formed, remarking, " Whatever the present mean thickness of 
all the sedimentary rocks of our globe may be, it must be small 
in comparison to the mean thickness of all the sedimentary 
rocks which have been formed. This is obvious from the fact 
that the sedimentary rocks of one age are partly formed from 
the destruction of the sedimentary rocks of former ages. From 
the Laurentian age down to the present day the stratified rocks 
have been undergoing constant denudation." This is perfectly 
true, and yet the mean thickness of that portion of the sediment- 
ary rocks which remains may not be very different from that of 
the entire mass, because denudation acts only on those rocks 
which are exposed on the surface of a country, and most largely 
on those that are upheaved ; while, except in the rare ease of an 

* Geolofjical Magazine, Vol. VIII., March, 1871. 

14 



910 



ISLANH LIFE. 



[P*IIT L 



extensive formation being quite horisontid, and wliolly exposed 
to the seu or to tlio atmospiierc, (lenudntion can have no tenden- 
cy to diminish the thickness of any entire deposit.' ITnlesa, 
tlierefore, a f-oi'ination is completely destroyed by dcnudaliou in 
every part of the world {a thing very improbable), we may have 
in existing roeks a not \cry inadcqnate representation of the 
mean thickness of all that Jiavo been formed, and even of the 
innximiim thickness of the larger portion. This will be the 
more likely because it is almost certain that many rocks con- 
temporaneously formed are counted by geologist* as distinct 
formations whenever they differ in lithological character or in 
organic remains. Bat we know that limestones, sandstones, and 
shales are always forming at tiie same time; while a great dif- 
ference in organic remains may arise from comparatively slight 
changes of geographical features, or from difference in the depth 
or purity of the water in which the animals lived.' 

Ifow to Eatimate the Avera</e Rat^ of Deposition of the Sed- 
imentary liocks. — But if we take the estimate of Profrasof 
Ilanghton (177,200 feet), which, as we have seen, is probably ex- 
cessive, for the maximum thickness of the sedimentary rocks of 
the globe of all known geological ages, can we arrive at any es- 
timate of the rate at which tliey were formed! Dr. CroU lias 
attempted to make such an estimate, hut he has taken for liis 
basis the menu thickness of the rocks, which we hare no means 
whatever of arriving at, and which he guesses, allowing for den- 
udation, to be ecjunl to the maximum thickness as measured by 
geologists. The land area of the globe is, according to Dv. Croll, 



' Mr. C. Lloyd Moignn lm» ivell illujiiniieJ ihis poinl liy comparinp th* eenornllj 
tilicdnp simta denuded on iheir cilgca to n librar; in wliirh n fire Unit ocied on tiM 
esiKiud edgei if ilie books, doiniyii'g n giiaii Tnnis ot llientiiiri!, but lenvlnE n por- 
tion c>r«nL-li b"ok in '«» ptnccwlikh ponion ra]>n>»ciii3 ibeibickiiesi,but nut ibe aiie, 
of the book {dtoloijicat Maagxiiir.. 1878, p. nil). 

' ProTussor J, yonng iliinki it blKbly probnUe ibnt "iho I^oivcr Greensnnd !■ 
contempornncoui wiili jmrt or iho Clinlk, co wore pnrts of ilie Woolden ; nny, even 
oflbe Purbeck n pniiiun mual have bean formiiig w|iile the CrtftnceouB sea niLs gnul- 
iinll; d«e|ieninB uvuibniirtl und tveslwnrd." Yet llie«e ilejiosits nra nhrnys uminged 
naccesMvely, nnd their sevaml ibieknesiea added togelbor to obliiin tiie lotnl lliiok- 
ne<s of itie formntiont of tlie couiirry. (9m Fresideiiliui Addrasi, Sect. C. Britidi 
Aasociniioii, IS 'IS.) 



Chap.X.] the EARTH'S AGE. 211 

57,000,000 square miles, and he gives the coast-line as 116,000 
miles. This, however, is, for onr purpose, rather too much, as it 
allows for bays, inlets, and the smaller islands. An approxi- 
mate measurement on a globe shows that 100,000 miles will be 
nearer the mark, and this has the advantage of being an easily 
remembered even number. The distance from the coast to 
which shore-deposits usually extend may be reckoned at about 
one hundred or one hundred and fifty miles, but by far the 
larger portion of the matter brought down from the land will 
be deposited comparatively close to the shore ; that is, within 
twenty or thirty miles. If we suppose the portion deposited 
beyond thirty miles to be added to the deposits within that dis- 
tance, and the whole reduced to a uniform thickness in a direc- 
tion at right angles to the coast, we should probably include all 
areas where deposits of the maximum thickness are forming at 
the present time, along with a large but unknown proportion of 
surface where the deposits were far below the maximum thick- 
ness. This follows, if we consider that deposit must go on very 
unequally along different parts of a coast, owing to the distance 
from each other of the mouths of great rivers and the limita- 
tions of ocean currents; and because, compared with the areas 
over which a thick deposit is forming annually, those where 
there is little or none are probably at least twice as extensive. 
If, therefore, we take a width of thirty miles along the whole 
coast-line of the globe, as representing the area over which de- 
posits are forming, corresponding to the maximum thickness 
as measured by geologists, we shall certainly over- rather than 
under-estimate the possible rate of deposit.' 

' As by far the larger portion of the denuded matter of the globe passes to the sen 
through comparatively few great rivers, the deposits must often be confined to very 
limited areas. Thus the denudation of tiie vast Mississippi basin must be almost aU 
deposited in a limited portion of the Gulf of Mexico, that of the Nile within a small 
area of the Eastern Mediterranean, and that of the great rivers of China — the Iloang 
Ho and Yang-tse-kiang — in a small portion of the Eastern Sea. Enormous lengths 
of coast, like those of Western America and Eastern Africa, receive very scanty de- 
posits; so that thirty miles in width along the whole of the coasts of tiie globe will 
probably give an area greater than that of the area of average deposit, and certainly 
greater than that of maximum deposit, which is the basis on which I have here made 
my estimates. In the cose of the Mississippi, it is stated by Count Pourtales that 



218 



ISLAND LIFE. 



{Ptasl. 



Now a coast-line of 100,000 miles with a widtli of 30 gives an 
area of 3,UOO,000 eqiiare miles, on wliieli the denuded matter of 
the whole land urea of 57,000,000 eijuare miles is deposited. As 
these two areas ate as 1 to 19, it follows that deposition, as meas- 
ured by maximuiu thickness, goes on at least nineteen times as 
fast as denudation — probably very much faster. Uut the mean 
rate of denudation over the whole earth is about one foot in 
lliree thousand years ; therefore the mte of maximum deposition 
will be at least nineteen feet in the same time ; and as the total 
inaximam thickness of all the stratified rocks of the globe is, ac- 
eording to Professor Hangliton, 177,200 feet, the time reijiiired 
to produce this thickness of rock at the present rate of denuda- 
tion and deposition is only 28,000,000 years." 

T/ie Hate of Geological C'fiange Prohahhj Greater in very lie- 
mote Times. — The opinion that denudation and deposition went 
on more rapidlj'in early times owing to the frequent occurrence 
of vast convulsions and cataclysms was strenuously opposed by 
Sir Charlea Lyell, who so well showed that causes of the very 
same nature as those now in action were sufficient to account for 
all the phenomena presented by the rocks throughout the whole 
series of geological formations. Kut while upholding the sonnd- 



ntoiiK tlie plfltenu between ilie momh of [lie river nnd Ihe floiirliorn extremitrof Ilor. 
idn, Tur Itvo liundred nnil llfly miles in niilth,lho boilom consisls ofclnr with some 
dnnil nnd lut few Ithiiopods ; but beyond this distance iho noiindingB brought ap el- 
tlier KhUopod fhelli olune, or these mixed niih coml innd, Nullipons), and other 
calcareoni organisms (Diina'i "Manual of Geuloe;," Sd ed., p. GT1J. It i» probable, 
therefore, that n birgo proponlon of the entire moM of lediment brouglit down bj 
tlio Mississippi ii deposiied on tlio IJtnited area above indicated. 

Professor Dunn fitrtber remmki, "Over inteiior ocennie lasina, na ivcl] ns ofTa 
tonsi in quiet depllis, fifteen or tnenly fiiihoms and beyond, tho deposila are mostly 
uffine silt, fliled Kir lanking line nrf[illnc«oiisrovk>,nsihnles or slates. When, hoir. 
ever, the depth of ilio occnn fulls off below a hundred fjiilionu, the dqiosiiion of silt 
in our existing oceans motlly censes, unlcu In the cnso of a gieat bank along the 
lionlerorni 

' From tlie «i 
million jenrt for the duration nl illogical lime; but be ai 
•ntiposing tliG prodacts of denudation to be uniromily spread ov 
lorn instead of over n nnrrow bell ncnr the consis — a supposilioi 



ir Ilnughlon Ci 



of two h nnd red 

this CDnclasion by 
tlie whole ita-l/ol- 
inlirely opposed in 
■II the kiinun faeis, nnd which had been eiiown by Dr. Croll Are yenn previously to 
be altngetber erroneauf. (Sec Nalyre. Vol. XVIJI., p. 3G8, nbere frofossor Uaugh- 
ton's |<i>[>ei' is i^ven as read bcfiirc the Itoynl Society.) 



Ohap.X.] the EAUTH'S AGE. 213 

ness of the views of the ^^ unif ormitarians " as opposed to the 
" convulsionists," we must yet admit tliat tliere is reason for be- 
lieving in a gi*adaally increasing intensity of all telluric action 
as we go back into past time. This subject has been well treated 
by Mr. W. J. SoUas,* who shows that if, as all physicists main- 
tain, the sun gave out perceptibly more heat in past ages than 
now, this alone would cause an increase in almost all the forces 
that have brought about geological plienomena. With greater 
heat there would be a more extensive aqueous atmosphere, and 
a greater difference between equatorial and polar temperatures ; 
hence, more violent winds, heavier rains and snows, and more 
powerful oceanic currents, all producing more rapid denudation. 
At the same time, the internal heat of the earth being greater, 
it would be cooling more rapidly, and thus the forces of con- 
traction — which cause the upheaving of mountains, the eruption 
of volcanoes, and the subsidence of extensive areas — would be 
more powerful and would still further aid the process of denu- 
dation. Yet again, the earth's rotation was certainly more rapid 
in very remote times, and this would cause more impetuous 
tides and still further add to the denuding power of the ocean. 
It thus appears that as we go back into the past, all the forces 
tending to the continued destruction and renewal of the earth's 
surface would be in more powerful action, and must, therefore, 
tend to reduce the time required for the deposition and upheav- 
al of the various geological formations. It may be true, as many 
geologists assert, that the changes here indicated are so slow 
that they would produce comparatively little effect within the 
time occupied by the known sedimentary rocks; yet, whatever 
effect tliey did produce would certainly be in the direction here 
indicated, and as several causes are acting together, their com- 
bined effect may have been by no means unimportant. It must 
also bo remembered that such an increase of the primary forces 
on whicli all geologic change depends would act with great ef- 
fect in still further intensifying those alternations of cold and 
warm periods in each hemisphere, or, more frequently, of exces- 
sive and equable seasons, which have been shown to be the re- 

• 

' See Geological MagcLziM for 1877, p. 1. 



314 



ISLAXD UPE. 



Stilt of astroDouiical combined with geograpliical rerolntloDs; 
and this would again increase the rapidity of denudation and 
depofiition, and tUua still fnrtlier reduce the time required for 
tbe production of the known eedimentary rocts. It k evident, 
therefore, that tlieee various considerations all combine to prove 
that, in supfwaing that the rate of denudation has been on tbc 
average only what it is now, we are almost certainly overesti- 
mating the time re(inired to have prodnced the whole scries of 
forniatione from the Cambrian upwards. 

Value of the Preceding Ultimate of Oeological Time. — It is 
not, of course, supposed that the calculation here given makes 
any approach to accuracy, but It is believed that it does indicate 
the order of magnitude of the time required. We have a certain 
number of data which are not guessed, but the result of actual 
racasuremeut; such are, the amount of solid matter carried down 
by rivers, the width of the belt within which this matter is miiiu- 
ly deposited, and the maximum tbickne^ of the known stratitied 
rucks.' A considerable but miknown amount of denudation is 
effected by the waves of the ocean eating away coast-lines. This 
was once thought to be of more importance than sobacrial denu- 
dation, bnt it is now believed to be comparatively slow in its ac- 
tion.' Whatever it may be, however, it adds to the rate of for- 
mation of new strata, and its omission from the calculation is 
again on the side of making the lapse of time greater rather than 
lees than the trne amount. Even if a considerable modification 



' Tn lii> reply to Sir W. Thomson, I'mfeimr Huxley owmBfrf one foot iti n lliou- 
Hniiil .veori oa a not improbibla raia of (lepositlon. Tlie nbuve u'timntu inilirnics a 
fur lilglicr rate ; and tliia fullowt fr<>m llie «cll-nicGniiineil fuel that ibc area of depo- 
*ilinn i« many ilmca imnller ll>nn ilie nron of denudniion. 

' Dr. Croll and ProfoMr Geiki« havt shomi tlmt mnrine denudation is very small 
In amnunt u com)iaTed niili labneriiil, lince it acts only locnily on tlie tJje cf the 
lanil, wliercaa the tnllor acts over every fi>ot of the nuface. Mr. W. T. lllnnfoid ar- 
Bueit ihnl the dtflercnce is ilill erenier in tropicnl than in icmpernie laliludes, and ar- 
rive* Dl the concliiiinn that "if over Ilriiish Indiii the effects or marine lo those of 
freiih-wi>t«r denudation in removing tho roclts of the country be estimated at 1 to 
100, I Uilieve that the result of marina action wiH ba grenily overstated "("Geoli^ey 
and Zoology of Ahy»»inia," p. I ns, note). Now, as our estimate of the mle of »ulw 
oerial deiiucjniion cannot pretend lo any jireciiio nccuracy, we nro justificil in neglect- 
i>i|t marine denudation allogvilior. e»]>ecially na we linvc no merhod of Bstimaiin({ It 
For ilia iihole earth witli any approach to coirGctnesj. 



Chap,X.] the rate of ORGANIC CHANGE. 215 

should be needed in some of tlie assumptions it lias been neces- 
sary to make, the result must still show that, so far as the time re- 
quired for the formation of the known stratified rocks, the hun- 
dred million years allowed by physicists is not only ample, but 
will permit of even more than an equal period anterior to the 
lowest Cambrian rocks, as demanded by Mr. Darwin — a demand 
supported and enforced by the arguments, taken from indepen- 
dent standpoints, of Professor Huxley and Professor Ramsay. 

Organic Modification Dependent on Change of Conditions, — 
Having thus shown that the physical changes of the earth's sur- 
face may have gone on much more rapidly and occupied much 
less time than has generally been supposed, we have now to in- 
quire whether there are any considerations which lead to the 
conclusion that organic changes may have gone on with corre- 
sponding rapidity. 

Tliere is no part of the theory of natural selection which is 
more clear and satisfactory than that which connects changes of 
specific forms with changes of external conditions or environ- 
ment. If the external world remains for a moderate period un- 
changed, the organic world soon reaches a state of equilibrium 
througli the struggle for existence; each species occupies its 
place in nature, and there is then no inherent tendency to 
change. But almost any change whatever in the external world 
disturbs this equilibrium, and may set in motion a whole series 
of organic revolutions before it is restored. A change of climate 
in any direction will be sure to injure some and benefit other 
species. The one will consequently diminish, the other increase, 
in number; and the former may even become extinct. But the 
extinction of a species will certainly affect other species which 
it either preyed upon, or competed with, or served for food; 
while the increase of any one animal may soon lead to the ex- 
tinction of some other to which it was inimical. These changes 
will in their turn bring other changes; and before an equilibrium 
is again established the proportions, ranges, and numbers of the 
species inhabiting the country may be materially altered. The 
complex manner in which animals are related to each other is 
well exhibited by the importance of insects, which in many 
parts of the world limit the numbers or determine the very ex- 



ISLAND LIPE. 



[Paw I. 



isteiice of some of tlie Itigticr animals. Mr, Dai-win savs, " Per- 
haps Paraguay offers the most cnrious instance of tliis ; for here 
neither cattle nop horses nor dogs have ever nm wild, though 
tliey swai-Li southward and northward iira wild state ; and Aza- 
ra and Ketiggcr have shown that this is caused by tlie greater 
numbor in Paragnay of a certain fly which lays its eggs in the 
navels of these animals wlien first born. The increase of these 
liiee, numei'oiia as tliey are, must be habilnally checked by some 
means, probably by other parasitic insects. Hence, if certain in- 
sectivorous birds were to decrease in Paraguay, tlie parasitic in- 
sects would probably increase; and this would lessen llie nnm- 
ber of navel-frequenting flies ; then cattle and lioraea would run 
wild ; and this would certainly alter (as, indeed, I liave observed 
in parts of Sonth America) the vegetation ; this, again, would 
largely affect the insects, and this, as we have seen in Stafliord- 
shire, the insectivorous birds, and so onward in ever-increasing 
circles of complexity." 

Geographical changes wonid be still move important, and it is 
almost impossible to exaggerate the modiflcations of the organic 
world that might result from them. A subsidence of land sep- 
arating a large island from a continent would affect the animals 
and plants in a variety of ways. It would at once modify the 
climate, and so produce a series of changes from tJiis cause alone ; 
but moi-e important would be its effect by isolating small groups 
of individuals of many species, and tlins altering their relations 
to the rest of the organic world. Many of these would at once 
be exterminated, while others, being relieved from competition, 
might flonrish and become modified into new species. Even 
more striking would be the effects when two continents, or any 
two land areas which had been long separated, were united by an 
upheaval of tlio strait which divided them. Numbers of ani- 
mals would now be brouglit into competition for tlie first time. 
New enemies and new competitors would appear in every part 
of the country; and a struggle would commence which, after 
many fluetnations, would certainly result in tho extinction of 
some species, the moditlcation of others, and a considerable al- 
teration in llie proportionate numbers and the geograpjiical dis- 
tribution of almost all. 



Chap.X.] the rate of ORGANIC CHANGE. 217 

Any otlier changes which led to the intermingling of species 
whose ranges were usually separate would produce correspond- 
ing results. Thus, increased severity of winter or summer tem- 
perature, causing southward migrations and the crowding to- 
gether of the productions of distinct regions, must inevitably 
produce a struggle for existence which would lead to many 
changes both in the characters and the distribution of ani- 
mals. Slow elevations of the land would produce another set of 
changes, by affording an extended area in which the more domi- 
nant species might increase their numbers ; and, by a greater 
range and variety of Alpine climates and mountain stations, af- 
fording room for the development of new forms of life. 

Geographical Mutations as a Motive Power in Bringmg about 
Organic Changes, — Now, if we consider the various geographical 
changes which, as we have seen, there is good reason to believe 
have ever been going on in the world, we shall find that the 
motive power to initiate and urge on organic changes has never 
been wanting. In the first place, every continent, though per- 
manent in a general sense, has been ever subject to innumerable 
physical and geographical modifications. At one time the total 
area has increased, and at another has diminished ; great plateaus 
have gradually risen up, and have been eaten out by denudation 
into mountain and valley ; volcanoes have burst forth, and after 
accumulating vast masses of eruptive matter have sunk down 
beneath the ocean, to be covered up with sedimentary rocks, and 
at a subsequent period again raised above the surface ; and the 
loci of all these grand revolutions of the earth's surface have 
changed their position age after age, so that each portion of 
every continent has again and again been sunk under the ocean 
waves, formed the bed of some inland sea, or risen high into 
plateaus and mountain-ranges. How great must have been the 
effects of such changes on every form of organic life ! And it is 
to such as these we may perhaps trace those great changes of 
the animal world which have seemed to revolutionize it, and 
have led us to class one geological period as the age of reptiles, 
another as the age of fishes, and a third as the age of mammals. 

But such changes as these must necessarily have led to re- 
peated unions and separations of the land masses of the globe, 



S18 



ISLAND LIFE. 



[P*B» I. 



joining together continents wliicli were before divided, and 
breaking up others into great islands or extensive archipelagoes. 
Such alterations of the means of transit would probably affect 
the organic world even moi'e profoundly than tlie changes of 
area, of altitude, or of climate, since they afforded the means, at 
long intervals, of bringing the most diverse forma into competi- 
tion, and of spreading all the great animal and vegetable types 
widely over the globe. But the isolation of considerable masses 
of land for long periods also afforded the means of preservation 
to many of the lower types, which tlius had time to beeome 
modified into a variety of distinct forms, some of which became 
8o well adapted to special modes of life that they have continued 
to exist to the present day, thus affording us examples of the 
life of early ages which would probably long since have becouio 
extinct, had they been always subject to the competition of the 
more highly organized animals. As examples of sncli excessive- 
ly archaic forms, we may mention the mnd-tishes and the ganoids, 
coiitiued to limited fresh-water areas : the frogs and toads, wbioh 
still maintain theniselvcB vigorously in competition with higher 
forms; and among mammalB the Ornithorhynchns and EchiduR 
of Auatralia; the whole oi-der of Marsiipiala — which, out of 
Australia, where they are (^uite free from competition, only exist 
abundantly in Sonth America, which was certainly long isolated 
from the nortliern continent; the Insoctivora, which, though 
widely scattered, are generally noetnrnul or subterranean in their 
habits; and the I^emurs, which are most abundant in Madagas- 
car, where they have long been isolated, and almost removed 
from the comjictilion of higher forms. 

Climatal Jieco/utions as an A(/erit in Producing Organic 
Cfitini/c. — The geographical and geological changes we have 
been considering are probably those which have been most ef- 
fective in bringing abont the great features of the distribution 
of animals, as well us the larger movements in the development 
of organized beings; b[it it is to the alternations of warm and 
cold, or of unifortn and excessive climates — of almost perpetual 
spring in arctic as well as in temperate lands, with occasional 
phases of cold culminating at remote intervals in glacial epochs 
— that wo must impute some of the more remarkable cbiinges 



Chap.X.] THb RATE OF ORGANIC CHANGE. 219 

both in the specific characters and in the distribution of organ- 
isms.* Although the geological evidence is opposed to the be- 
lief in early glacial epochs except at very remote and distant in- 
tervals, there is nothing which contradicts the occurrence of re- 
peated changes of climate, which, though too small in amount 
to produce any well-marked physical or organic change, would 
yet be amply sufficient to keep the organic world in a constant 
state of movement, and which, by subjecting the whole flora and 
fauna of a country at comparatively short intervals to decided 
changes of physical conditions, would supply that stimulus and 
motive power which, as we have seen, is all that is necessary to 
keep the processes of "natural selection" in constant operation. 
The frequent recurrence of periods of high and of Jow eccen- 
tricity must certainly have produced changes of climate of con- 
siderable importance to the life of animals and plants. During 
periods of high eccentricity with summer in perihelion, that 
season would be certainly very much hotter, while the winters 
would be longer and colder than at present ; and although geo- 
graphical conditions might prevent any permanent increase of 
snow and ice even in the extreme North, yet we cannot doubt 
that the whole Northern Hemisphere would then have a very 
different climate than when the changing phase of precession 
brought a very cool summer and a very mild winter — a perpet- 
ual spring, in fact. Now such a change of climate would cer- 
tainly bo calculated to bring about a considerable change of 
species^ both by modification and migration, without any such 
decided change of type^ either in the vegetation or the animals, 
that we could say from their fossil remains that any change of 
climate had taken place. Let us suppose, for instance, that the 
climate of England and that of Canada were to be mutually ex- 
changed, and that the change took five or six thousand years to 
bring about ; it cannot be doubted that considerable modifications 
in the fauna and flora of both countries would be the result, al- 
though it is impossible to predict what the precise changes would 

' Agnssiz appears to have been the first to suggest that the principal epochs of life- 
extermination were cpoclis of cold ; and Dana thinks that two at least such epochs 
may be recognized, at the clo}»e of the Palieozoic and of the Cretaceous periods, to 
which we may add tlie hist ghicial epoch. 



320 ISLAND LIFE. [Paki Z 

be. We call safely say, however, that some speeiea wonld stand 
the change better than otlierci, nliile it is highly probable tlint 
some ■would be actually beuelited by it, and others would bo 
injured. 13nt the benefited would certainly increase and the 
injured decrease in consequence, and thns ft series of changes 
wonld be initiated that might lead to most important rcBiilts. 
Again, we are sure that some species would become modified in 
adaptation to the change of climate more readily than others, 
and these modified species would therefore increase at the ex- 
pense of others not so readily modified ; and hence would arise, 
on the one hand, extinction of species, and, on the other, the pro- 
dnction of new forms. 

But thi^ is the very least amount of change of climate that 
would certainly occni- every 10,500 years when there was a high 
eccentricity, for it is impossible to doubt that a varying distance 
of the sun in enmmer from 86 to 89 millions of miles (which 
is what occurred during — as supposed — the Miocene period, 
850,000 yeara ago) would produce an important difference in 
the summer temperature and in the actinic inliucuco of sunshine 
on vegetation. For the intensity of the sun's rays would vary 
as tilt) wjiiarc of the distance, or nearly as 74 to 98, so that the 
earth wonld be actually receiving one fourth less sun heat dur- 
ing summer at one time than at the other. An etjnally high 
eccentricity occurred 2,500,000 years back, and, no doubt, was 
often reached during etill earlier epochs, while a lower but still 
very high eccentricity has frequently prevailed, and is probably 
near its average value. Changes of climate, therefore, every 
10,500 years, of the character above indicated and of varying 
intensity, have been the rule rather than the exception in past 
time; and these changes must have been variously modified by 
changing geographical conditions so as to produce climatic alter- 
ations in different directions, and giving to the ancient lands 
either dry or wet seasons, storms or calms, equable or excessive 
tenipenitures, in a variety of combinations of which the earth 
perhaps affords no example under the present low phase of ec- 
centricity and consequent slight inequality of sun heat. 

J'reseiit Ct»uIition of the Earth one of Excepiionjd StahUlty 
as ivt/ards Vli/nafe. — It will be seen by a reference to the dia- 



Chap.X.] the rate of ORGANIC CHANGE. 221 

gram at page 163 that during the last 3,000,000 years the eccen- 
tricity has been less than it is now on eight occasions, for short 
periods only, making up a total of about 280,000 years ; while 
it has been more than it is now for many long periods, of from 
300,000 to 700,000 years each, making a total of 2,720,000 years, 
or nearly as 10 to 1. For nearly half the entire period, or 
1,400,000 years, the eccentricity has been nearly double what it 
is now, and this is not far from its mean condition. We have 
no reason for supposing that this long period of 3,000,000 years 
for which we have tables was in any way exceptional as regards 
the degree or variation of eccentricity ; but, on the contrary, we 
may pretty safely assume that its variations during this time 
fairly represent its average state of increase and decrease during 
all known geological time. But when the glacial epoch ended, 
72,000 years ago, the eccentricity was about double its present 
amount ; it then rapidly decreased till, at 60,000 years back, it 
was very little greater than it is now, and since then it has been 
uniformly small. It follows that, for about 60,000 years before 
our time, the mutations of climate every 10,500 years have been 
comparatively unimportant, and that the temperate zones have 
enjoyed an exceptional stability of climate. During this time 
those powerful causes of organic change which depend on con- 
siderable changes of climate, and the consequent modifications, 
migrations, and extinctions of species, will not have been at 
work ; the slight changes that did occur would probably be so 
slow and so little marked that the various species would be able 
to adapt themselves to them without much disturbance; and 
the result would be an epoch of exceptional stability of species. 

But it is from this very period of eocceptional stability that we 
obtain our only scale for measuring the rate of organic change. 
It includes not only the historical period, but that of the Swiss 
Lake dwellings, the Danish shell -mounds, our peat-bogs, our 
sunken forests, and many of our superficial alluvial deposits — 
the whole, in fact, of the iron, bronze, and neolithic ages. Even 
some portion of the palaeolithic age and of the more recent 
gravels and cave-earths may come into the same general period, 
if they were formed when the glacial epoch was passing away. 
Now throughout all these ages we find no indication of change 



328 



ISLAND LIFK. 



of speciee, and biit little, comparatively, of migration. Wc tliuB 
get an erroDeous idea of the permanence and aUihility of specijic 
forms, due to tlie period immediately autecedent to oui- own 
h&m^a period of exceptiontU permanence and ainhiliti/ as regards 
climatic and geographical conditions.' 

Date of Lodi Glacial Epochs and its Bearing on the Measure- 
ment of Geological Time. — Dinictly we go back fi-oni this stable 
period, wc come upon changes both in the forms and in the dis- 
tribntion of species; and when we pass beyond the last glacial 
epoch into the Pliocene period, we lind onrselves in a compara- 
tively new world, surrounded by a considerable number of spe- 
cies altogether different from any which now exist, together 
■with niauy others which, though still living, now inhabit distant 
regions. It seenie not improbable that what is termed the Pli- 
ocene period was really the coining-on of the glacial epoch, and 
tliis is the opinion of Professor Jules Marcou.' According to 
our views, a considerable amount of geographical cliange must 
have occnrred at the change from tlie Miocene to the Pliocene, 
favoring the refrigeration of tlie Northern Hemisphere, and 
leading, in the way already pointed out, to the glacial epoch 
whenever a high degree of eccentricity prevailed. As many 
reasons combine to make us fix the height of the glacial epoch 
at the period of high eccentricity which occurred 200,000 yeara 
back, and as the Pliocene period was proliably not of long dura- 
tion, we must suppose the next great phase of very liigh cccen- 
tpicity (860,000 yeare ago) to fall within the Miocene epoch. 
Dr. Croll believes that this must have produced a glacial period, 
but we have shown strong reasons for believing that, in concur- 
rence with favorable geographical conditions, it led to uninter- 
rupted warm climates in the temperate and northern zones. 



' Tills view wns, I helicre, flnt put forlli hy myse\{ In n popor reiid bebre the Geo- 
logical Section of ibe Briiiih Anocintion in ISCU, nnd iiitiKiiiieiiily in nn ariirle in 
ffitfHn. Vol. I..p.4nt. ll WHS nl«> EtAi«d by Mr. S. B. K. Skeruliley )n liis "I'lij-a- 
icnlSrslcta of ihe Univercc," p. aca (IS7S}; but we luth foiiiided iion ivlmt 1 now 
cvaaidsr tiic emineoni dociriiio ihni nclunl einrini cpoclis rccuri'cd cncli 10,.iOO jaan 
during period* of liigli wcentricirv, 

' " Kxplicnlion d'uneSocandQ^diilon ds laC*rte GtfologiquedelnTorro"(ldTfi), 



Chap.X.] measurement OF GEOLOGICAL TIME. 223 

This, however, did not prevent the occurrence of local glacia- 
tion wherever other conditions led to its initiation, and the 
most powerful of such conditions is a great extent of high land. 
Now we know that the Alps acquired a considerable part of 
their elevation during the latter part of the Miocene period, 
since Miocene rocks occur at an elevation of over 6000 feet, 
w^hile Eocene beds occur at nearly 10,000 feet. But since that 
time there has been a vast amount of denudation, so that these 
rocks may fii-st have been raised much higher than we now find 
them, and thus a considerable portion of the Alps may once 
have been more elevated than now. This would certainly lead 
to an enormous accumulation of snow, which would be increased 
when the eccentricity reached a maximum, as already fully ex- 
plained, and may then have caused glaciers to descend into the 
adjacent sea, carrying those enormous masses of rock which are 
buried in the Upper Miocene of the Superga in Northern Italy. 
An earlier epoch of great altitude in the Alps, coinciding with 
the very high eccentricity 2,500,000 years ago, may have caused 
the local glaciation of the Middle Eocene period when the enor- 
mous erratics of the Flysch conglomerate were deposited in the 
inland seas of Northern Switzerland, the Carpathians, and the 
Apennines. This is quite in harmony with the indications of 
an uninterrupted warm climate and rich vegetation during the 
very same period in the adjacent low countries, just as we find 
at the present day in New Siealand a delightful climate and a 
rich vegetation of Metrosideros, fuchsias and tree-ferns on the 
very borders of huge glaciers, descending to within seven hun- 
dred feet of the sea-level. It is not pretended that these esti- 
mates of geological time have any more value than probable 
guesses; but it is certainly a curious coincidence that two re- 
markable periods of high eccentricity should have occurred at 
such periods and at such intervals apart as very well accord with 
the comparative remoteness of the two deposits in which un- 
doubted sisjis of ice-action have been found, and that both these 
are localized in the vicinity of mountains which are known to 
have acquired a considerable elevation at about the same period 
of time. 

In the tenth edition of the "Principles of Geology," Sir 



ISLAND LIFS. 

Charles Lyell, taking tlie amount of change in the species of 
inollusca as a guide, estimated the time elapsed since tlie com- 
meuccment of the Miocene as one third that of tlie whole Ter- 
tiary epoch, and the latter at one fourth that of geological time 
since the Cambrian period. Professor Dana, on the other liaud, 
estimates the Tertiary as only one fifteenth of the Mesozoic and 
Paljeozoic combined. On the estimate above given, founded on 
the dates of phases of high eccentricity, we shall arrive at about 
four million years for the Tertiary epoch, and &i.\teen million 
years for the time elapsed since the Cambrian, accoi-ding to Lyell, 
or sixty millions according to Dana. The estimate arrived at 
from the rate of denudation and deposition (twenty-eight million 
years) is nearly midway between these, and it is, at al! events, 
satisfactory that the various measures result in figures of the 
same order of magnitude, which is all one can expect on so dif- 
ficult and exceedingly speculative a subject. 

The only value of such estimates is to define our notions of 
geological time, and to show that the enormous periods of hun- 
dreds of millions of years which have sometimes becu indicated 
by geologists are neither necessary nor warranted by the facts 
at our command; while the pi-esent result places ns more in 
harmony with the calculations of physicists, by leaving a very 
wide margin between geological time as defined by the fossilif- 
erous rocks and that fur more extensive period which includes 
all possibility of life upon the earth. 

Vondiidimj iieincwhs. — In the present chapter I have endeav- 
ored to show that, combining the measured i-ate of denudation 
with the estimated thickness and probable extent of the known 
scries of sedimentary rocks, we may arrive at a rude estimate of 
the time occupied in the formation of those rocks. From hii- 
other point of departure — that of the probable date of the Mio- 
cene period as determined by the epoch of high eccentricity 
supposed to have aided in the production of the Alpine glncia- 
tiou during that period, and taking the estimate of geologists as 
to the proportionate amount of change in the animal world since 
that epoch — wo obtain another estimate of the duration of geo- 
logicnl time, which, though founded on far less secure data, agrees 
pretty nearly with the former estimate. The time thus arrived 



^BQ^. 



Chap.X.] MEASUliEMENT OF GEOLOGICAL TIME. 225 

at 18 immensely less than the usual estimates of geologists, and 
is so far within the limits of the duration of the earth as cal* 
culated by Sir William Thomson as to allow for the develop- 
ment of the lower organisms an amount of time anterior to the 
Cambrian period several times greater than has elapsed between 
that period and the present day. I have further shown that, in 
the continued mutations of climate produced by high eccentric- 
ity and opposite phases of precession, even though these did 
not lead to glacial epochs, we have a motive power well calcu- 
lated to produce far more rapid organic changes than have hith- 
erto been thought possible; while in the enormous amount of 
specific variation (as demonstrated in an earlier chapter) we have 
ample material for that power to act upon, so- as to keep the 
organic world in a state of rapid change and development pro- 
portioned to the comparatively rapid changes in the earth's sur- 
face. 

We have now finished the series of preliminary studies of the 
biological conditions and physical changes which have afiooted 
the modification and dispersal of organisms, and have thus 
brought about their actual distribution on the surface of the 
earth. These studies will, it is believed, place us in a condition 
to solve most of the problems presented by the distribution of 
animals and plants, whenever the necessary facts both as to their 
distribution and their affinities are sufficiently well known ; and 
we now proceed to apply the principles we have established to 
the interpretation of the phenomena presented by some of the 
more important and best known of the islands of our globe, 
limiting ourselves to these for reasons which have been already 
suflSciently explained in our preface. 

15 



Part IL 



INSULAR FAUNAS AND FLORAS 



CHAPTER XI. 

THE CLASSIFICATION OF ISLANDS. 

Importance of I&lands in the Study of the Distribution of Organisms. — Classification 
of Islands with lieference to Distribution. — Continental Islands. — Oceanic Islands. 

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

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

Importance of Idands in the Study of the Distribution of 
Organisms. — Islands possess many advantages for the study of 
the laws and phenomena of distribution. As compared with 
continents they have a restricted area and definite boundaries, 
and in most cases their geographical and biological limits coin- 
cide. The number of species and of genera they contain is 
always much smaller than in the case of continents, and their 
peculiar species and groups are usually well defined and strictly 
limited in range. Again, their relations with other lands are of- 
ten direct and simple, and even when more complex are far 
easier to comprehend than those of continents ; and they ex- 
hibit, besides, certain influences on the forms of life and certain 
peculiarities of distribution which continents do not present, and 
whose study offers many points of interest 



230 



ISLAND LIFE. 



Vfxxt IL 



In islands wc liave tlio facts of distriliuticni often presented 
to lis in tlicir simplest forms, along with otliere which become 
gmdnall^ more and more complex ; luid we are therefore able to 
proceed step by step in the solution of the problems tlioj present. 
But as in studying these problems we have uecessarilj to take 
into acconnt tbc relations of the insular and continental faunas, 
wc also get some knowledge of the latter, and acquire besides so 
much command over the general principles which underlie all 
problems of distribution that it is nut too mnch to say that when 
we have mastered the difficuUies presented by the pecuHarittes 
of island life we shail find it comparatively easy to deal with the 
more complex and less clearly defined problems of continental 
distribution. 

Vlaasifii^tion ofhlamh with liefr-ivitee to Diniribution. — Isl- 
ands have had two distinct modes of origin : they have cither 
boon separated from continents of which they ^va but detached 
fragments, or they have originated tn the ocean and have never 
formed part of a continent or any large mass of land. This 
difference of origin is fundameutal, and leads to a most im- 
portant difference in their animal inhabitants; and we may 
therefore first distinguish the two classes — oci-anic and conti- 
nental islands. 

Mr. Darwin appeare to have been the first writer who called 
attention to the number and importance, both from n geological 
and biological point of view, of oceanic islands, ]Ie showed 
that with very few exceptions all the remoter islands of the 
great oceans were of volcanic or coralline formation, and that 
none of them contained indigenous mammalia or amphibia. lie 
also showed the connection of these two phenomena, and inain- 
taiucd that none of the islands bo characterized Iiad ever formed 
part of a continent. This was quite opposed to the opinions of 
llie Bcientilic men of the day, who almost all held the idea of 
continental extensions, and of oceanic islandB being their frag- 
ments, and it was long before Mr. Darwin's views obtained gen- 
eral acceptance. Even now the belief still lingers; and we con- 
tinually hear of old Atlantic or Pacific continents, of " Atlantis " 
or "Lemuria,'' of which hypothetical lands many existing isl- 
ands, atthnugli wholly volcanic, arc tliouglit to be iho reujnants. 



Chap. XL] THE CLASSIFICATION OF ISLANDS. 231 

We have already seen that Darwiii connected the peculiar geo- 
logical structure of oceanic islands with the permanence of the 
great oceans which contain them, and we have shown that sev- 
eral distinct lines of evidence all point to the same conclusion. 
We may therefore define oceanic islands as follows : Islands of 
volcanic or coralline formation, usually far from continents, and 
alwaj's separated from them by very deep sea ; entirely without 
A indigenous land mammalia or amphibia, but with abundance of 
birds and insects, and usually with some reptiles. This defini- 
tion will exclude only two islands which have been sometimes 
>^ classed as oceanic — Xew Zealand and the Seychelles. Kodri- 
guez, which was once thought to be another exception, has been 
shown by the explorations during the Transit of Venus Expedi- 
tion to be essentially volcanic, with some upraised coralline lime- 
stone. 

CmitinenioX Inlands. — Continental islands are always more 
varied in their geological formation, containing both ancient 
and recent stratified rocks. They arc rarely very remote from 
a continent, and they always contain some land mammals and 
amphibia, as well as representatives of the other classes and 
orders in considerable variety. They may, however, be divided 
into two well-marked groups — ancient and recent continental 
islands — the characters of which may be easily defined. 

Recent continental islands arc always situated on submerged 
banks connecting them with a continent, and the depth of the 
intervening sea rarely exceeds 100 fathoms. They resemble the 
continent in their geological structure, while their animal and 
vegetable productions are either almost identical with that of 
the continent, or, if otherwise, the difference consists in the pres- 
ence of closely allied species of the same types, with occasionally 
a very few peculiar genera. They possess, in fact, all the charac- 
teristics of a portion of the continent, separated from it at a 
recent geological period. 

Ancient continental islands differ greatly from the preceding 
in many respects. They are not united to the adjacent conti- 
nent by a shallow bank, but are usually separated from it by a 
depth of sea of a thousand fathoms or upwards. In geological 
structure they agree generally with the more recent islands; 




laL&ND LIFE. 



[P»ltT U. 



like them they poeseaa mammalia and amphibia, uenally in con- 
eiderable abundance, as well aa all other claases of aniiuala ; but 
these are higlilj peculiar, almost all being diatiiict species, and 
many forming distinct and peculiar genera or families. They 
arc also well characterized by the fragmentary nature of their 
fauna, many of the most characteristic continental oi-ders or 
families being quite unrepresented, while some of their animals 
arc allied, nut to such forma as inhabit the adjacent continent, 
but to others found only in remote parts of the world. This 
very remarkable set of characters mark off the islands which 
exhibit them as a distinct class, which often present the great- 
est anomalies and most difficult problems to tlie student of dis-, 
tribntion. 

Oceanic Jdaiids. — The total absence of warm-blooded terres- 
trial animals in an island otherwise well suited to maintain 
them is held to prove that such island is no mere fragment 
of any existing or submerged continent, but one that lias been 
actually produced in mid-ocean. It is true that if a continental 
island were to be comjileteiy submerged for a single day and 
then again elevated, its higher terrestrial animals would be 
all destroyed; and if it were situated at a considerable dis- 
tance from land, it would be reduced to the same zoological 
condition as an oceanic island. But such a complete snb- 
roergeuce and re-elevation appears never to have taken place, 
for there is no single island on the globe which has the phyei- 
cal and geological features of a continental combined with 
the roological features of an oceanic island. It is true that 
some of the coral islands may be formed upon submerged lands 
of a continental character, but we have no proof of this; and 
even if it were so, the existing islands arc to all intents and pur- 
poses oceanic. 

We will now pass on to a consideration of some of the more 
interesting examples of these three classes, beginning with oce- 
anic islands. 

All the animals which now inhabit such oceanic islands must 
either themselvos have reached them by erossiug the ocean, or 
be the descendants of ancestors who did so. lit us, then, see 
what are, in fiict, the animal and vegetable inhnbitnnts of these 



Chap. XL] THE CLASSIFICATION OF ISLANDS. 233 

islands, and bow far their presence can be accounted for. We 
will begin with the Azores, or Western Islands, because they 
have been thoroughly well explored by naturalists, and in their 
peculiarities aflFord us an important clew to some of the most 
efficient means of distribution among several classes of animals. 



234 ISLAND LIFE. [Pabt IL 



CHAPTER XII. 

OCEANIC ISLANDS.— THE AZORES AND BERMUDA. 

The AzorkS) or Western Islands. — Position and Physicnl Featares. — Chief Zo- 
ological Features of the Azores. — Birds.— Origin of the Azorean Bird Fauna. — 
Insects of the Azores. — Land Shells of tlie Azores. — The Flora of the Azores. — 
The Dispersal of Seeds. — Birds as Seed-camers. — Facilities for Dispersal of Azo- 
rean Plants. — Important Deduction from the Peculiarities of the Azorean Faana 
and Flora. 

Bermuda. — Position and Physical Featui-es. — The Red Clay of Bermuda. — Zoology 
of Bermuda. — Birds of Bermuda.— Comparison of the Bird Faunas of Bermuda and 
tiie Azores. — Insects of Bermuda. — Land MoIIusca. — Flora of Bermuda. — Con- 
cluding Remarks on the Azores and Bermuda. 

We will commence our investigation into the phenomena pre- 
sented by oceanic islands with two groups of the North Atlan- 
tic, in which the facts are of a comparatively simple nature, and 
such as to afford us a valuable clew to a solution of the more dif- 
iicult problems we shall have to deal with further on. The 
Azores and Bermuda offer great contrasts in physical features, 
but striking similarities in geographical position. The one is 
volcanic, the other coralline ; but both are surrounded by a wide 
expanse of ocean of enormous depth, the one being about as far 
from Europe as the other is from America. Both are situated 
in the temperate zone, and they differ less than six degrees in 
latitude, yet the vegetation of the one is wholly temperate, while 
that of the other is almost tropical. The productions of the one 
are related to Europe, as those of the other are to America, but 
they present instructive differences; and both afford evidence of 
the highest value as to the means of dispersal of various groups 
of organisms across a wide expanse of ocean. 

THE AZORES, OR WESTERN ISLANDS. 

These islands form a widely scattered group, nine in number, 
situated between 37° and 30° 40' N. lat., and stretching in a 



CHAr. XII.] 



OCEANIC ISLANDS. 



SQuUieast and nortiiwest direction over a distance of iionHy 400 
miles. Tlie largest of the islauds, San Miguel, is about 40 miles 
long, mid is oue of tlio nearcet to Europe, being rather under 
900 miles from the coast of Portugal, from which it la separated 
hy an ocean 2500 fathoms deep. Tlic depth between tlie ieluTids 
does not seem to be known, but tlio 1000-fatlioui line endoses 
the whole group pretty olostly, while a depth of about 1800 




—The liglit linl b1 
Tho figures slio 






ileptba in futlioni!. 



L...... ^. 

^^1 great depths render it in the highcBt dcgi-ee improbable that the 

^^1 Azores have ever been united with the Earopcan continent; 

^^H while their being wholly volcanic is eqnally opposed to the view 

^^M of their liuviiig farmed part of an estensive Atlantis including 

^^1 Madeira and the Canaries. The only exception to their volcanic 

^^H etrnctiiro is the occurieuce in one small iijland only (Santa Ma- 



ISLAND LIFE. 



[Piax II. 



ria) of Boiiic triai'ino deposits of Upper Miocene age — a fact 
wLicli proves some alteralious of level, and perhaps a greater 
extension of this island at some former period, but in no way 
indii'atca a former nuion of the islands, or any greater extension 
of the whole group. It proves, however, that the gronp is of 
considerable antiquity, since it must date back to Miocene times ; 
and this fact may be of importance in considering the origin and 
peculiar features of the fiinna and flora. It thus appears that in 
all physical features the Azores correspond strictly with oar 
deHnition of " oceanic islands ;" while their great distance from 
any other land, and the depth of the ocean around them, make 
them typical examples of the class. We shonld therefore expect 
them to be equally typical in their fauna and flora ; and this is 
the case as regards the most important charaetenstics, although 
in some points of detail they present exceptional phenomena. 

Chief ZiKihiijlcal J'entnres of the Azores' — Tiie great feature 
of oceanic islands — the absence of all indigenous land mammalia 
and amphibia — is well shown in this group; and it is even car- 
ried further, so as to include all terrestrial vertebrata, there being 
no snake, lizard, frog, or fresh-water fish, although the islands 
are sutticiently extensive, possess a mild and equable climate, and 
are in every way adapted to support all these groups. On the 
other hand, flying creatnres, as birds and insects, are abundant ; 
and tliere is also one flying mammal — a small European bat. It 
is true tliat i-abbits, weasels, rats and mice, and a email lizard 
peculiar to Madeira and Teneriffe are now found wild in the 
Azores, but there is good reason to believe that these have all 
been introduced by liuman agency. The same may be said of 
the gold-flsh and eels now found in some of tiie lakes, there be- 
ing not a single fresli-waler fish which is truly indigenous to the 
islands. When we consider that the nearest part of tlio gi-oup 
is about BOO miles from Portugal and moi-e than 550 miles from 
Madeira, it is not surprising that none of these terrestrial ani- 
mals can have passed over sucti a wide expanse of ocean unas- 
sisted by man. 



' For mnai of ilie fiicW as t 

In Mr. Goilmim'a vnliiabls ii 
jmUs," by Frecleriik Ma Ciiiie 



laionlogy oad botnn.roriheseiKlniidilm 
. " Xnltiral Hi«lory of tliG A^orej, or W 
idm-in, F.L.S., F.Z.S., etc., London. IB? 



nU- 




Chap. XII.] THE AZORES. 237 

Let us now sec what animals are believed to have reached the 
group by natural means, and thus constitute its indigenous fauna. 
These consist of birds, insects, and land shells, each of which 
must be considered separately. 

Birds, — Fifty-three species of birds have been observed at the 
Azores, but the larger proportion (thirty-one) are either aquatic 
or waders — birds of great powei^s of flight, whose presence in 
the remotest islands is by no means remarkable. Of these two 
groups twenty are residents, breeding in the islands, while eleven 
are stragglers, only visiting the islands occasionally, and all are 
common European species. The land birds, twenty-two in num- 
ber, are more interesting, four only being stragglers, while eigh- 
teen are permanent residents. The following is a list of these 
resident land birds : 

1 . Common Buzzard Buteo vulgaris, 

2. Long-eared Owl Asio otua, 

3. Barn Owl Strixjiammea. 

4. Blackbird Turdus merula, 

5. liobin Erithacut rubecula, 

6. Blackcap Sylvia airicapilla, 

7. Gold-crest Regulus cristatus. 

8. Wheat-ear Saxicola ctnanthe, 

9. Grajr Wagtail Motacilla sulphurea. 

1 0. Atlantic Chaffinch FnngiUa tintilion, 

11. Azorean Ballfinch Pyrrhula murina, 

1 2. Canary Serinus Canarius, 

13. Common Starling Stumus vulgaris, 

1 4. I.,esser Spotted Woodpecker Dryohates minor, 

14. Wood -pigeon Columha palumbus. 

IG. Rock-dove Columha livta, 

17. Red-legged Partridge Caccabis rufa. 

1 8. Common Quail Cotumix communis. 

All the above-named birds are common in Europe and North 
Africa except three — the Atlantic chaffinch and the canary, 
which inhabit Madeira and the Canary Islands, and the Azorean 
bullfinch, which is peculiar to the islands we are considering. 

Origin of the Azorean Bird Fauna. — The questions we have 
now before us are — how did these eighteen species of birds first 
reach the Azores, and how are we to explain the presence of a 
single peculiar species while all the rest are identical with Euro- 
pean birds? In order to answer them, let us first see what 



ISLAND LIFE. 



CI'Airt II. 



stragglers now actually visit the Azores from the nearest conti- 
nents. The four Bpecies given in Mr. Ooduian'a list are tlie 
kestrel, the oriole, tlio snow-bunting, and the hoopoe; but he 
also tells lis that there are certainly others, and adds, "Scarcely 
a storm occurs in spring or autntnn without bringing one or 
more species foreign to the ishmds ; and I have frequently been 
told that swallows, larks, grebes, and other species not referred 
to here are not nncoininonly seen at those seasons of tJie 
year." 

We Iiave therefore every reason to believe that the biids 
which are now residents originated as stragglers, which occa- 
sionally fonnd a haven in these remote islands when driven ont 
to sea by storms. Some of tlicm, no donbt, still often arrive 
fron] the continent, bnt these cannot easily be distinguished as 
new arrivals among those which are residents. Many facts men- 
tioned by Mr. Godman show that this is the case. A barn 
owl, much exhausted, Hew on board a whaling-ship when 500 
miles Eonthwest of the Azores; and even if it had come froin 
Madeira it must have travelled quite as far as from Portugal tu 
the islands. Mr. Godniau also shot a single specimen of tlic 
wheat-ear in Flores after a strong gale of wind ; and as no one on 
the island knew the bird, it was almost certainly a recent arrival. 
Subsequently a few wore found breeding in the old crater of 
Corvo, a small adjacent island ; and as the species is not found 
in any other island of the group, we may infer that this bird is 
A recent immigrant in process of establisliing itself. 

Another fact which is almost eonelnsive in favor of the bii-d- 
population having arrived as stragglers is that they are most 
abundant in the islands nearest to Eurepe and Africa. The 
Azores consist of three divisions — an eastern, consisting of two 
islands, St. Michael's and St. Mary's; a central, of five, Tercoira 
Graciosa, St. George's, Pico, and Fayal ; and n western, of two, 
Flores and Corvo. Now, had the whole group once been united 
to the continent, or oven formed [wrts of one extensive Atlantic 
island, wc should certainly expect the central group, which is 
more compact and has a much larger area than all ihe rest, to 
have the greatest nnmbor and variety of birds. Bnt the fact 
that bird^ are most numerous in the eastern group, and diminish 



Chap. XII.] THE AZORES. 23J) 

as we go westward, is entirely opposed to this theory, while it 
is strictly in accordance with the view that they are all strag- 
glers from Europe, Africa, or the other Atlantic islands. Omit- 
ting oceanic wanderers, and including all birds which have prob- 
ably arrived involuntarily, the numbers are found to be forty 
species in the eastern group, thirty-six in the central, and twenty- 
nine in the western. 

To account for the presence of one peculiar species, the bull- 
finch (which, however, does not diflfer from the common Euro- 
pean bullfinch more than do some of the varieties of North 
American birds from their type-species), is not difficult, the 
wonder rather being that there are not more pecuh'ar forms. In 
our third chapter we have seen how great is the amount of in- 
dividual variation in birds, and how readily local varieties be- 
come established wherever the physical conditions are sufficient- 
ly distinct. Now we can hardly have a greater difference of 
conditions than between the continent of Europe or North Af- 
rica and a group of rocky islands in mid-Atlantic, situated in 
the full couree of the Gulf Stream and with an excessively mild 
though stormy climate. We have every reason to believe that 
special modifications would, soon become established in any ani- 
mals completely isolated under such conditions. But tliey are 
not, as a rule, thus completely isolated, because, as we have seen, 
stragglers arrive at short intervals ; and these, mixing with the 
residents, keep up the purity of the breed. It follows that only 
those species which reach the Azores at very remote intervals 
will be likely to acquire well-marked distinctive characters ; and 
this appears to have happened with the bullfinch alone, a bird 
which docs not migrate, and is therefore less likely to bo blown 
out to sea, more especially as it inhabits woody districts. A few 
other Azorean birds, however, exhibit slight diflferences from 
their European allies. 

There is another reason for the very slight amount of peculi- 
arity presented by the fauna of the Azores as compared with 
many other oceanic islands, dependent on its comparatively re- 
cent origin. The islands themselves may be of considerable an- 
tiquity, since a few small deposits, believed to be of Miocene 
age, have been found on them ; but there can be little doubt that 



ISLAND LIFE. 



[PawIL 



their present fauna, at all events as eoncernB the birds, bad its 
origin since the date of the last glacial epoch. Eveu now ice- 
bergs reach tlie latitude of the Azores only a little to the west- 
ward; and when we consider the proofs of extensive ice-action 
in North America and Europe, we can hardly doubt that these 
islands were at that time surrounded with pack-ice, while their 
own mountains, reaching 7600 feet high in Pico, would almost 
certainly have been covered with perpetual snow and havo 
sent down glaciei-s to the sea. They might then have had a 
elimste almost as bad as that now endured by the Prince Ed- 
ward Islands in the Southern llemisphere, nearly ten degrees 
farther from the equator, wliere there are no land bii-ds what- 
ever, although the distance from Africa is not much greater 
tjjan that of the Azores from Europe, white the vegetation 
is limited to a few alpine plants and mosses. This recent ori- 
gin of the birds accounts, in a great measure, for their identity 
with those of Europe, because, whatever change has occurred 
must have been effected in the islands themselves, and in a time 
limited to that which has elapsed since the glacial epoch passed 
away. 

//(«(■<.*» of the Azores. — Having thus found no difficulty in ac- 
counting for the peculiarities presented by the birds of these 
Islands, wo have only to see how far the same general principles 
will apply to the insects and land shells. The buttcrliies, moths, 
and hynienoptera are few in number, and almost all seem to be 
common European si>ecies, whose presence is explained by tlie 
same causes as those which have Introduced the birds. Beetles, 
however, are more numerous, and have been better studied, and 
these present some features of interest. The total nnmber of 
species yet known is :il2, of which 17j are European ; but out 
of these 101 are believed to have been introduced by human 
agency, leaving seventy-four really indigenous. Twenty-three of 
these indigenous &ix^cies are not found in any of the other Atlan- 
tic islands, showing that tlicy have been introduced directly from 
Europe by causes which have acted more powerfully here than 
farther south. Besides these, there are thlity-six species not 
found in Europe, of which nineteen are natives of JIadoira or 
the Canaries, three are Anieriean, and fuiirtcen are altogether 



Chap. XII.] THE AZORES. 241 

pecnliar to the Azores. These latter are mostly allied to spe- 
cies found in Europe or in the other Atlantic islands, while one 
is allied to an American species, and two are so distinct as to 
constitute new genera. The following list of these peculiar spe- 
cies will be interesting : 

CARABlDiE. 

Anchomenus aptinoides Allied to a species from the Canaries. 

Bembidium htsperus Allied to the European B. Icetum. 

DlTIRCID^. 

Agahua Godmanni, Allied to the European A, dispar. 

COLTDlID-«. 

Tarphius Wollastoni A genus almost peculiar to the Atlantic Islands. 

Elate BiD.«. 

Heteroderes Azorictts Allied to a Brazilian species. 

Elastrus dolosus Belongs to a peculiar Madagascar genus. 

Meltrid^. 
Attains miniaticollis Allied to a Canarinn species. 

Rhyncophora. 

Phlatophagus variabilis Allied to European and Atlantic species. 

Acalles Lh-oueti A Mediterranean and Atlantic genus. 

Laparocerus Azoricus Allied to Madeiran species. 

Asynonychus Godmanni. A peculiar genus, allied to Brachyderes of the 

South of Europe. 
Neocnemis occidentalis A peculiar genus, allied to the European genus 

Strophosomus, 

Heteromera. 
Helops Azoricus Allied to U, vulcanus of Madeira. 

Staphylinid*. 
Xenomma melanocephala Allied to X.fiUforme from the Canaries. 

This greater amount of speciality in the beetles than in the 
birds may be due to two causes. In the first place, many of 
these small insects have, no doubt, survived the glacial epoch, 
and may, in that case, represent very ancient forms which have 
become extinct in their native country ; and, in the second place, 
insects have many more chances of reaching remote islands than 
birds, for not only may they be carried by gales of wind, but 
sometimes, in the egg or larva state, or even as perfect insects, 
they may be drifted safely for weeks over the ocean, buried in 

16 



s^ 



ISLAXD LIFE. 



[PaktIL 



the liglit Btema of plants or in tlie solid wood of trees in wliicli 
many of them undergo their trnnEformntions, Thoa wo may 
explain the presence of three common South American epeciea 
(two elaters and a longiuorn), ail wood-eaters, and tliereforo 
liable to be occasionally hronght in Uoating timber by the Gnlf 
Stream. But insects are also immensely more numcvoue in spe- 
L-ies than are land birds, and tJieir ti-ansmission M'onid bo in most 
cases qnitc invohintary, and not dependent on their own powers 
of Hight.ns ^vitli birds; and tliiis the chances against iJiu same 
species being frequently carried to the same island would be 
considerable. If wo add to this the dependence of so many in- 
sects on local conditions of climate and vegetation, and their 
iiability to Ije destroyed by insectivorous birds, we shall see that, 
although there may be a greater probability of insects as a whole 
reaching the islands, the chances against any particular insect 
arriving there, or against the same species arriving fitquently, 
are mucli greater tlian in the case of birds. Tlie i-cstilt is that 
(us compared with Britain, for example) the birds are propor- 
tionately much more iinmcrous than the beetles; while the pe- 
culiar species of beetles are innch more numerous than among 
birds, both facts being quite in accordance with what we know 
of the habits of the two f^roups. We may also remark that the 
small size and obscure characters of many of the beetles render 
it probable that species now supposed to be peculiar really in- 
habit some parts of Europe or North America. 

It is interesting to note that tlie two families which are pre- 
eminently wood, loot, or seed eatere arc those which present the 
greatest amount of speciality. Tlie two ElatcridsB alone exhibit 
remote affinities, the one with a Brazilian, the other with a Mad- 
agascar gronp; while the only peenliar genera belong to the 
Rhynoophora, but are allied to European forms. These last al- 
most certainly form a portion of the more ancient fauna of the 
islands which migrated to them in proglacial times, while the 
Brazilian elater appears to be the solitary example of a living 
insect brought by the Gnif Stream to these remote shores. The 
elater, having its nearest living ally in Madagascar {J^la^trua 
(lologtis), cannot be held to indicate any independent communi- 
cition between these distant islands; but is more probably a 



Chap.XIL] the AZORES. 243 

relic of a once more wide-spread type which has only been able 
to maintain itself in these localities. Mr. Crotch states that 
there are some species of beetles common to Madagascar and 
the Canary Islands, while there are several genera common to 
Madagascar and South America, and some to Madagascar and 
Australia. The clew to these apparent anomalies is found in 
other geneiti being common to Madagascar, Africa, and South 
America, while others are Asiatic or Australian. Madagascar, 
in fact, has insect relations with every part of the globe, and 
the only rational explanation of such facts is that they are in- 
dications of very ancient and wide-spread groups, maintaining 
themselves only in a few widely separated portions of what was 
at one time or another the area of their distribution. 

Land Shelh of the Azores. — Like the insects and birds, the 
land shells of these islands have a generally European aspect, 
but with a larger proportion of peculiar species. This was to 
be expected, because the means by which mollusks are carried 
over the sea are far less numerous and varied than in the case of 
insects;* and we may therefore conclude that their introduction 
is a very rare event, and that a species once arrived remains for 
long periods undisturbed by new arrivals, and is therefore more 
likely to become modified by the new conditions, and then fixed 
as a distinct type. Out of the sixty-nine known species, thirty- 
seven are connnon to Europe or the other Atlantic islands; while 
thirty-two are peculiar, though almost all are distinctly allied to 
European types. The majority of these shells, especially the 
peculiar forms, are very small, and many of them may date back 
to beyond the glacial epoch. The eggs of these would be ex- 
ceedingly minute, and might occasionally be carried on leaves 
or other materials during gales of exceptional violence and dura- 
tion, while others might be conveyed with the earth that often 
sticks to the feet of birds. There are also, probably, other un- 
known means of conveyance; but, however this may be, the 
ffcneral character of the land mollusks is such as to confirm the 
conclusions we have arrived at from a study of the birds and 
insects — that these islands have never been connected with a 

* See Chap. V., p. 74. 



244 



ISLAND LrPK. 



[Part II. 



continent, and have been peopled with living things by such 
forms only as in some way or other have been able to reacli 
them across many hundred miles of ocean. 

The Flora of the Azores. — The flowering plants of the Aaores 
have been gtiidied by one of our first botanists, Mr, H. C.Wat- 
eon, who lias himself vigited the islands and made extensive col- 
lections; and he lias given a complete catalogue of the species 
in Mr. Godmaii's volume. As our object iu the present work is 
to trace the past history of the mora important islands by means 
of the forms of life that inhabit them, and as for this purpose 
plants are sometimes of more vulne than any class of animals, 
it will be well to take advantage of the valuable materials here 
available in order to ascertain how far the evidence derived from 
the two organic kingdoms agrees in character; and also to ob- 
tain some general results which may be of service in onr dis- 
cussion of more difficult and more complex problems. 

There are in the Azores 480 known species of flowering plants 
and ferns, of which no less than 440 are found also in Europe, 
Madeira, or the Canary Islands ; while forty are peculiar to the 
Azores, but are more or less closely allied to European species. 
As botanists are no less prone than zoologists to invoke former 
land-connections and continental extensions to account for the 
wide dispersal of objects of their stndy, it will be well to ex- 
amine somewhat closely what these facts really imply. 

The Di«peraai of Seeds. — The seeds of plants are liable to bo 
dispersed by a greater variety of agents than any other organ- 
isms, while their tenacity of life, under varying conditions of 
heat and cold, drought and moisture, is also exceptionally great. 
They have also an advantage, in that the great majority of flovr- 
ering plants Iiave the sexes united in the same individual, so 
that a single seed in a state fit to germinate may easily stock a 
whole island. The dispersal of seeds has been studied by Sir 
Joseph Hooker, Mr. Darwin, and many other writers, who have 
made it suflieicntly clear that they are in many cases liable to be 
carried enormous distances. An immense number are specially 
adapted to bo carried by the wind, through the possession of 
down or hairs or memhrimoiis wings or processes; while otliere 
are so minute, and produced in such profusion, that it is difficult 



Chap. XII.] THE AZORES. 245 

to place a limit to the distance thej might be carried by gales 
of wind or hurricanes. Another class of somewhat heavier 
seeds or dry fruits are capable of being exposed for a long time 
to sea-water without injury. Mr. Darwin made many experi- 
ments on this point, and he found that many seeds, especially 
of atriplex, beta, oats, capsicum, and the potato, grew after one 
hundred days' iinmei*8ion, while a large number survived fifty 
days. But he also found that most of them sink after a few 
daj's' immersion, and this would certainly prevent them being 
floated to very great distances. It is very possible, however, 
that dried branches or flower-heads containing seeds would float 
longer, while it is quite certain that many tropical seeds do float 
for enormous distances, as witness the double cocoa-nuts which 
cross the Indian Ocean from the Seychelle Islands to the coast 
of Sumatra, and the West Indian beans which frequently reach 
the west coast of Scotland. There is therefore ample evidence 
of the possibility of seeds being conveyed across the sea for great 
distances by winds and surface currents.* 

Birds as Seed-carriers. — The great variety of fruits that are 
eaten by birds afford a means of plant-dispersal in tlie fact that 
seeds often pass through the bodies of birds in a state well fitted 
for germination; and such seeds may occasionally be carried 
long distances by this means. Of the twenty-two land birds 



* Some of Mr. Darwin's experiments nre very interesting and suggestive. Ilii>e 
hazel-nuts sank immediately, but when dried they floated for ninety days, and after- 
wards germinated. An asparagus-plant with ripo berries, w lien dried, floated for 
eighty-five days, and the seeds afterwards germinated. Out of ninety-four dried 
plants experimented with, ciglitecn floated for more than a month, and some for 
three months, and their powers of germination seem never to have been wholly de- 
stroyed. Now, as oceanic currents vary from thirty to sixty miles a day, snch plants 
under the most favorable conditions might be carried 90 X GO — 5400 miles ! But even 
lialf of this is ample to enable them to reach any oceanic island, and we must remem- 
ber that till completely water-logged they might be driven along at n much gi-eater rate 
by the wind. Mr. Danvin calculates the distance by the average time of flotation to 
lie *J24 miles; but in such a case as this we are entitled to take the extreme cases, 
because such coinitless thousands of plants and seeds must be carried out to sea an- 
nually that the extreme cases in a single experiment with only ninety-four plants 
must hn])pen hundreds or thousands of times, and with hundreds or thousands of spe- 
cies, naturally, and thus aflurd ample opportunities for successful migration. (See 
** Origin of Species," Gth ed., p. 325.) 



ISLAND lATO. 



IPamt 11. 



fonnd ill the Azores, balf arc more or less frnit-eaters, and these 
may have been the means of introducing some plants into the 
islande. 

Birds also frequently have small portions of earth on their 
feet J and Mr. Darwin has shown by actual experiment that al- 
moet all such earth contains seeds. Thus, in nine grains of earth 
on the leg of a woodcock a seed of the toad-riish was found 
which germinated; while n wounded red-logged partridge had 
A ball of earth weighing six and a half ounces adhering to its 
leg. and from this earth Mr. Darwin raised no less than eighty- 
two separate plants of about five distinct species. Still mora 
remarkable was the experiment wilh six and three -qnarter 
ounces of nmd from the edge of a little pond, which, carefully 
treated under glass, produced 537 distinct plahts! This is 
equal to a seed for every six grains of mud ; and when we 
consider how many birds freqnent tlio edges of ponds in search 
of food, or come thcro to drink, it is evident that great num- 
bers of seeds may be dispersed Ity this means- 
Many seeds have hispid awns, hooks, or prickles which readily 
attach them to the feathers of bii-ds, and a great number of 
aquatic birds nest inland on the ground; and as these- are pre- 
eminently wanderers, they ranst often aid in the dispersal of 
such plants.' 

' Tlio fuUowiiig rcmarbK, kindly communicnlcd lo me by Mr. II. N. Moseley, 
nnlum11«i lo ilia CAnlltaijrr, titrou miicli light on the ngency uf birils in itie dinribu- 
tlonof|i1aiiu; "OiiwI>nch("Veg, JerEiile,"VuLII., p.41Hi)lnrsinucliilres»onllie 
niile rnnging of ilio ntlMiiroai (nioniaticii) ucnm* iho eqiulor from Cupe Horn to the 
Karile IeIhiiiI*, and tliinki tlini the prcMnce of ttie aaina ptnnls in Krclic nnJ niUDrctic 
I'exions mny be accounted for, ]>0KEib1y, by this fuel. I wui tniich struck nt .Mniion 
lalnnd, of liia Pilnco I^n'ird eroiip, by observing ihnl liio grcnt nlbiitrosa breeds in 
the miJit of It ilenie, law hevbnKe, nnd constriictj it* nett of n monnd of Inrf niid 
herbage. Some of the indigenous plnnts, e. g. Arivnn, hnvo flowor-liainis ivliicli slirlt 
like bniTs lo fentticni, elo., and scctn epecinlly adnjiled for imn9|<onnlion by birdn. 
Beaides the nlbntrosMs, vnriotu ipecies of Fiiwclbtria and Pufflnus, birds wliicli mnga 
ov«r injQiange distnncei, mny, I iliink, hare played a B>wt port in Iho disiribution of 
planM, and opecinlij nccount, in some menaure, far the oiheniisQ difficult fuct (nlien 
occurring in tlie tropica) ihnt nidely dislnnt iilnndi linrs sirailnr monntain pinnti. 
Tlie I'mcellnriii* nnd Paffinni, in neiting, bamnv in ihe emiiiiJ. as fur ni 1 have 
•e«n cliooting often places irhcro llic rcgetnliun is llie lliickesL Tlio birds in bur- 
ruwinf; gel llicir fenibci! corered uiiti vesciiible motihl, wliidi must incbido sporo) 
nnd vttail scuJi. In bigli Intitiidrs llio binU uftcn b.irroiT near ilic ■e.vlevcl, ns at 



Chap. XII.] THE AZORES. 247 

Facilities for Dispersal of Azorean Plants, — Now, in the 
course of very long periods of time, the various causes here 
enumerated would be sufficient to stock the remotest islands 
with vegetation, and a considerable part of the Azorean flora 
appears well adapted to be so conveyed. Of the 439 flowering 
plants in Mr. Watson's list, I find that about 45 belong to genera 
that have either pappus or winged seeds ; 65 to such as have 
very minute seeds; 30 have fleshy fruits such as are greedily 
eaten by birds ; several have hispid seeds; and 84 are glumaceous 
plants, which are all probably well adapted for being carried partly 
by winds and partly by currents, as well as by some of the other 
causes mentioned. On the other hand, we have a very suggestive 
fact in the absence from the Azores of most of the trees and 
shrubs with large and heavy fruits, however common they may 
be in Europe. Such are oaks, chestnuts, hazels, apples, beeches, 
aldei-s, and firs; while the only trees or large shrubs are the 
Portugal laurel, myrtle, laurestinus, elder, Laurus Canariensis, 
MyricaFaya, and a doubtfully peculiar juniper — all small berry- 
bearers, and therefore likely to have been conveyed by one or 
other of the modes suggested above. 

There can be little doubt that the truly indigenous flora 
of the islands is far more scanty than the number of plants 
recorded would imply, because a large but unknown propor- 
tion of the species are certainly importations, voluntary or in- 
voluntary, by man. As, however, the general character of the 
whole flora is that of the southwestern peninsula of Europe, 
and as most of the introduced plants have come from the 

Tristan d'Acunha or Kerguelcn Land ; but in the tropics they choose the mountains 
for their nestiug-phice (Finsch and Ilarthiub, "Ornith. der Viti- und Tonga-Inseln,** 
18G7, Einlcitung, p. xviii.). Thus, Puffinus Megasi nests at the top of the Korobasa 
basnga mountain, Viti Levu, fifty miles from tlio sea. A Procellaria breeds in like 
manner in the high mountains of Jamaica, I believe at 7000 feet. Peale describes 
the same habit of Procellana rostrata at Tahiti, and I saw the burrows myself 
amidst a dense growth of fern, etc., at 4400 feet deration in that island. Phaethon 
has a similar habit. It nests at the crater of Kilauea, Hawaii, at 4000 feet elevation, 
and also high up in Tahiti. In order to account for the transportation of the plants, 
it is not, ot course, necessary that the same species of Procellaria or Diomedea should 
now range between the distant points where the plants occur. The ancestor of the 
now ditlei ing sjiecies might have carried the seeds. The range of the genns is suf- 
ficient." 



848 



ISLAND LIFE. 



tPABTH. 



eume coiintrj', it ia alinost iiiipoeeible now to eepiirate tliem, 
and Mr. Wateon lias not attempted to do so. Tlie whole flora 
contains representatives of 80 natural orders and 250 genera; 
and even if we euppose that one half the species only aro truly 
indigenous, tliere will still remain a wonderfully rich and varied 
flora to have been carried, by the various natural means above 
indicated, over 900 milea of ocean, more especially as the 
large proportion of species identical with those of Europe 
shows that their introduction lins been comparatively recent, 
and that it is probably (as in the case of the birds) still going 
on. We may therefore feel eure that we have liere by no nioana 
reached the limit of distance to which plants can bo conveyed 
by natural means across the ocean ; and tins concUieion will be 
of great value to us in inveatignting other cases wlicre the evi- 
dence at our command is less complete and the iudifations of 
origin more obscnre or conflicting. 

Of the forty species which nre considered to be peculiar to 
the islands, all are allied to European plants except six, whoso 
nearest affinities are in the Canaries or Madeira, Two of the 
Oonipositfe are considered to be distinct genera, but in this or- 
der generic divisions rest on slight technical distinctions; and 
the t'ampantda VidtUii is veiy distinct from any otJier known 
species. With these exceptions, most of the peculiar Azorean 
species nre closely allied to European plants, and are in several 
cases little more than varieties of them. While, therefore, we may 
believe that the larger part of the existing flora reached the isl- 
ands since the glacial epoch, a portion of it may be more ancient, 
as there is no doubt that a majority of the species could withstand 
Eome lowering of temperature; while in such a warm latitude, 
and surrounded with sea, tliere would always be many sunny 
iind sheltered spots in which even tender plants might flourish. 

Jiii-porinnt Deduction from the Ptfculiaril'ws of the Asorean 
J^auiui and Flora.— TXiato is one conclusion to be drawn from 
the almost wholly European character of the Azorean fauna and 
flora which deserves special attention — namely, that the peopling 
of remote islands is not duo so ranch to ordinary or normal as 
to extraordinary and exceptional causes. These islands lie in 
tho coui-se of the southwesterly return trades and also of tlte 



Chap. XIL] BERMUDA. 249 

Gulf Stream, and we should tlrcrefore naturally expect that 
American birds, insects, and plants would preponderate if thej 
were conveyed by the regular winds and currents, which are 
both such as to prevent European species from reaching them. 
But the violent storms to which the Azores are liable blow from 
all points of the compass ; and it is evidently to these, combined 
with the greater proximity and more favorable situation of the 
coasts of Europe and North Africa, that the presence of a fauna 
and flora so decidedly European is to be traced. 

The other North Atlantic islands — Madeira, the Canaries, and 
the Cape Verds — present analogous phenomena to those of the 
Azores, but with some peculiarities dependent on their more 
southern position, their richer vegetation, and, perhaps, their 
greater antiquity. These have been sufficiently discussed in my 
" Geographical Distribution of Animals" (Vol. I., pp. 208-215); 
and as we are now dealing with what may be termed typical ex- 
amples of oceanic islands, for the purpose of illustrating the 
laws and solving the problems presented by the dispersal of 
animals, we will pass on to other cases which have been less fully 
discussed in that work. 

BERMUDA. 

The Bermudas are a small group of low islands formed of 
coral and blown coral-sand consolidated into rock. They are 
situated in 32° N. lat., about seven hundred miles from North 
. Carolina, and somewhat farther from the Bahama Islands, and are 
thus rather more favorably placed for receiving immigrants from 
America and its islands than the Azores are with respect to Eu- 
rope. There are about one hundred islands and islets in all, but 
their total area does not exceed fifty square miles. They are 
surrounded by reefs, some at a distance of thirty miles from the 
main group ; and the discovery of a layer of earth with remains 
of cedar trees forty-eight feet below the present high-water mark 
shows tliat the islands have once been more extensive, and prob- 
ably included the whole area now occupied by shoals and reefs.' 



* Nature, Vol. VI., p. 262; "Kecent Observations in the Bermudas," bjr Mr. J. 

Matthew Jones. 



250 



ISLAND LIFE. 



[Pabt H. 



Immediately beyond these reefs, however, entends a very deep 
ocean, while about four lumdreJ and fifty miles diatfliit in u 
Boiitheftst direction the deepest part of the North Atlantic is 
reached, where Bouiidiiigs of 3S25 and 3S75 fathoms have been 
obtained. It is clear, therefore, that these islands nre tvpieally 




IE.— The light lint indirulet 
'I'lia (Inrk tint " 
Tlio flcurcB allow tlia dcplli i 



fnthom*. 



Soundings were taken by tlic VhnUfngur in fonr different di- 
rections around Bcrmnda, and always showed a rapid deepening 
of the aea to about 2500 fathoms. This was bo remarkjiblo 
that, in his rcjwrts ti> tlio Admiralty, Captain Narcs epoko of 



Chap. XII.] 



BERMUDA. 



251 



Bermuda as " a solitary peak rising abruptly from a base only 
120 miles in diameter," and in another place as "an isolated 
peak rising abruptly from a very small base." These expres- 
sions sliow that Bermuda is looked upon as a typical exam- 
ple of an " oceanic peak ;" and on examining the series of offi- 
cial reports of the Challenger soundings, I can find no similar 
case, although some coasts, both of continents and islands, de- 
scend more abruptly. In order to show, therefore, what is the 
real character of this peak, I have drawn a section of it on a true 
scale from the soundings taken in a north and south direction 



N 



BERMUDA 



8 




-5S MILES- 



->^I8 MILCt-:>^ 



■46 MILES. 



SECTION OF BERMUDA Ain> ADJACENT SEA-BOTTOM. 

The figures sIiow the depth in fathoms nt fifty-fire miles north nnd furty-six miles 

south of the islands respectively. 

where the descent is steepest. It will be seen that the slope is 
on both sides very easy, being 1 in IC on the soutli, and 1 in 
19 on the north. The portion nearest the islands will slope 
more rapidly, perhaps reaching in places 1 in 10 ; but even this 
is not steeper than many country roads in hilly countries, while 
the remainder would be a hardly perceptible slope. Although 
generally very low, some parts of these islands rise to 250 
feet above the sea-level, consisting of various kinds of lime- 
stone rock, sometimes soft and friable, but often very hard and 
even crystalline. It consists of beds which sometimes dip as 
much as 30°, aild exhibit, besides, great contortions, so that at 
first sight the islands appear to exhibit on a small scale the phe- 
nomena of a disturbed Palaeozoic district. It has, however, long 
been known that these rocks are all due to the wind, which 
blows up the fine calcareous sand, the product of the disintegra- 
tion of coral, shells, serpulae, and other organisms, forming sand- 
hills forty and fifty feet high, which move gradually along, over- 
whelming the lower tracts of land behind them. These are con- 
solidated by the percolation of rain-water which dissolves some 



ISLAIID LIFE. 



[PaetIL 



of the lime from the more porous tracts aiid deposits it lower 
down, filling every fissure with stalagmite. 

The lied Clay of Bifmiuda. — Besides the calcareous rocks, 
there is found in many parts of tiie islands a layer of red earth 
or clay, containing about thirty per cent, of oxide of iron. This 
very closely resembles, both in color and chemical composition, 
the red clay of the ocean-floor, found widely spread in the At- 
lantic at depths of from SiSOO to 3150 fathoms, and occurring 
abundantly all ronnil Bermuda. It appears, therefore, at first 
Bight, as if the ocean-bed itself Ii,ie been Iiere raised to the sur- 
face, and a portion of its covering of red clay preserved ; and 
this is the view adopted by Mr. Jones in his paper ou the " Bot- 
any of Bermuda." lie sitys, after giving the analysis, ''Tiiia 
analysis tends to convince us that the deep ehocolate-colored 
red clay of the islands found in the lower levels, and from high- 
water mnrk some distance into the sea, originally came from the 
ocean-floor ; and that when by volcanic agency the Bermuda col- 
umn was raised from the depths of the sen, its summit, most 
probably broken in outline, appeared above the surface covered 
with this red mud, which in the course of ages has but slightly 
changed its composition, and yet possesses suflicient evidence to 
prove its identity with that now lying contiguous to the base of 
the Bermuda column." But in his "Guide to Bermuda" Mr. 
Jones tells us that this same red earth lias been found, two feet 
thick, under coral rock, at a depth of forty-two feet below low- 
wnter uiai'k, and that it "rested on a bed of compact oalcareons 
sandstone." Now it is quite certain that this "calcareous sand- 
stone" was never formed at the bottom of the deep ocean TOO 
miles from land; and the oeenrrence of the red earth at differ- 
ent levels upon coralline sand rock is therefore more probably 
due to some process of dccompositiou of the rotk itself, or of 
the minute organisms which abound in the blown sand. The 
fortlieoming volumes on the results of the ChaUengifp expedition 
will probably clear up the difficulty. 

Zotiogy of Bermuda. — As might be expected from their ex- 
treme isolation, these islands possess no indigenous land mam- 
malia, frogs, or snakes. There is. liowcver, one lizard, which 
Professor Cope considers to be distinct from any American spe- 



Chap. XII. ] BERMUDA. 253 

cies, and which he has named Plestiodon longirostris. It is said 
to be most nearly allied to P. fasciatus of the Southeastern 
States, from which it differs in having nearly ten more rows of 
scales, the tail thicker, and the muzzle longer. In color it is ashy 
brown above, greenish blue beneath, with a white line black- 
margined on the sides, and it seems to be tolerably abundant in 
the islands. This lizard is especially interesting as the only ver- 
tebrate animal which exhibits any peculiarity. 

Birds. — Notwithstanding its small size, low altitude, and re- 
mote position, a great number of birds visit Bermuda annually, 
some in large numbers, others only as accidental stragglers. Al- 
together, over a hundred and eighty species have been recorded, 
rather more than half being wading and swimming birds, whose 
presence is not so much to be wondered at, as they are great 
wanderers; while about eighty-iive are land birds, many of 
which would hardly be supposed capable of flying so great a 
distance. Of the hundred and eighty species, however, about 
thirty have only been seen once, and a great many more are 
very rare ; but about twenty species of land birds are recorded 
as tolerably frequent visitors, and nearly half these appear to 
come every year. 

There are only ten species which are permanent residents on 
the island — eight land and two water birds — and of these one has 
been almost certainly introduced. These resident birds are as 
follows : 

1. Gaieosroptes CaroHnensis. (The Catbird.) Migrates nloiig the east coast of 

the United States. 

2. Si alia si a f is. (The Bhiebird.) Migrates along the east coast. 

3. Vireo Novirboracensis, (Tiie White-eyed Green Tit.) Migrates along the east 

coast. 

4. Passer domesturus. (The English Sparrow.) ? Introduced. 

5. Corvus Atnericanus. (The American Crow.) Common over all North Amer- 

ica. 
G. Cardinalis Virgifdanus, (The Cardinal-bird. ) Migrates from Carolina south- 
ward. 

7. ChatfKppeiia passerina, (The Ground-dove.) Louisiana, West Indies, and 

Mexico. 

8. Orfi/x Virginianus. (The American Quail.) New England to Florida. 
0. Ardea herodias. (The Great Blue Heron.) All North America. 

10. Fulir.a Americana, (The American Coot.) Temperate and tropical North 
America. 



S54 



ISLAND LtFK. 



[I'abt II. 



It will be seen that those arc all very cQiiimon North Ameri- 
can birds, and most of them are constant visitors from the inaiii- 
Iiiiid, so thiit, liowever long they may linve inhabited the islands, 
there has been no chance for them to have acquired nny distinc- 
tive chamctere through isolation. 

Among the most regular visitants which are not resident are 
the common North American kingfisher (Ctryle alcifon), the 
wood-WHgtail {Siurus JVov^oracetisi-s), tlie wido-rauging rice- 
bird {Voliclionyx ori/sivora), and a moor-hen [OaUlitu/u galea- 
hi); the first three being very common over almost all North 
America, and the last abundant in the Boiithcrn portion of it. 

Com^rlaoii of the Bird Faunm of Bvrm'tda and the Azores. 
— The bird fauna of Bermud.i tiius diffcra from that of the 
Azores in the much smaller number of resident epecies and the 
presence of several regular migrants. This is due, first, to the 
small area and little-varied surfnce of these islands, as weJl as to 
their limited flora and small supply of insects not affording con- 
ditions suitable for the residence of many species all the year 
round ; and, secondly, to the peculiarity of the climate of North 
America, which causes a much Iarj;er number of its birds to be 
migratory than in Europe. The Northern United States and 
Canada, with a sunuy climate, luxuriant vegetation, and abun- 
dant insect life during tlie summer, snpply food and shelter to nn 
immense number of insectivorous and frugivorous birds; so that 
during the breeding season Canada is actually richer in bird life 
than Florida. But as the severe winter comes on, all these are 
obliged to migrate southward — some to Carolina, Georgia, and 
Florida, otliora as far as the West Indies, Mosico, or even to 
Guatemala and South AmeriiM. 

Every spring and autumn, therefore, a vast multilnde of birds, 
belonging to more than a hundred distinct species, migrate 
northward or southward in Eastern America. A large piftpor- 
tion of tlicsc pass along the Atlantic const; and it has been ob- 
served that many of them fly some distance out to sea, passing 
straigiit across bays from headland to headland by tlic shortest 
route. 

Now. as the time of these migrations is the season of storms, 
especially the autumnal one, which nearly coincides with the 



Chap. XII.J BERMUDA. 255 

liurricanes of the West Indies and the northerly gales of the 
coast of America, the migrating birds are very liable to be car- 
ried out to sea. Sometimes they may, as Mr. Jones suggests, be 
carried up by local whirlwinds to a great height, where, meeting 
with a westerly or northwesterly gale, they are rapidly driven 
seaward. The great majority, no doubt, perish, but some reach 
the Bermudas and form one of their most striking autumnal feat- 
ures. In October, Mr. Jones tells us, the sportsman enjoys more 
shooting than at any otlier time. The violent revolving gales, 
which occur almost weekly, bring numbers of birds of many 
species from the American continent, the different members of 
the duck tribe forming no inconsiderable portion of the whole; 
while the Canada goose and even the ponderous American 
swan have been seen amidst the migratory host. With these 
come also such delicate birds as the American robin {Turdua 
inigr atari U8\ the yellow-rumped warbler {Dendrceca caroncUa)^ 
the pine-warbler {Detidrceca pinus), the wood-wagtail {Siurus 
Nov(jeborac€n8is\ the summer redbird {Pyranga cestiva\ the 
snow-bunting {Plectrophanes nivalis)^ the redpoll {^giothus 
linarius\ the king-bird {Tyrannies Carolinenais)^ and many oth- 
ers. It is, no doubt, in consequence of this repeated immigration 
that none of the Bermuda birds have acquired any special pecu- 
liarity constituting even a distinct variety; for the few species 
that are resident and breed in the islands are continually crossed 
by individual immigrants of the same species from the mainland. 

Four European birds also have occurred in Bermuda — the 
wheat-ear {Saxicola cenanthe\ which visits Iceland and Lapland 
and sometimes the Northern United States; the skylark {Alavr 
(la arvensis\ but this was probably an imported bird or an es- 
cape from some ship; the land-rail {Crex praten8is\ which also 
wanders to Greenland and the United States ; and the common 
snipe {Scolopax gaUinago\ which occure not unfrequently in 
Greenland, but has not yet been noticed in North America. It 
is, however, so like the American snipe {S. WUsoni) that a strag- 
gler might easily be overlooked. 

Two small bats of North American species also occasionally 
reach the island, and these are the only wild mammalia except 
rats and mice. 



256 ISLAND LIFE. [Pabt IF. 

Insects of Bermuda, — Insects appear to be veiy scarce ; but 
it is evident from the lists given by Mr. Jones that only the 
more conspicuous species have been yet collected. These com- 
prise nineteen beetles, eleven bees and wasps, twenty-six butter- 
flies and moths, nine flies, and the same number of Hemiptera, 
Orthoptera, and Neuroptera respectively. All appear to be com- 
mon North American or West Indian species ; but until some 
competent entomological collector visits the islands it is impos- 
sible to say whether there are or are not any peculiar species. 

Land Mollusca. — The land shells of the Bermudas are some- 
what more interesting, as they appear to be the only group of 
animals except reptiles in which there are any peculiar species. 
The following list has been kindly furnished me by Mr. Thomas 
Bland, of New York, who has made a special study of the ter- 
restrial molhisks of the West Indian Islands. The species which 
are peculiar to the islands are indicated by italics : 

L18T OF THE Land Shells of Bebmcda. 

1. Succinea fulgens. (Ijea.) Also in Cuba. 

2. ** Bermudensis. (Pfeiffer.).. ** Bnrbndoes? 
8. " Margarita. (Pfr.) *' Hayti. 

4. Hyalina Bermudensis, (Pfr.) A peculiar form which, according to Mr. 

Binney, ** cannot be placed in any recog- 
nized genns." A larger sub-fossil variety 
also occurs, named H. Nelsoni by Mr. 
Bland, and which appears sufficiently 
distinct to be classed as another species. 

/i. ** cii'cunifii'mata. (Red field.) 

6. *' discrepans. (l*fr.) 

7. Patula Reiniana. (Pfr.) 

8. ** hypolepta. (Shuttleworlh.). .Probably the same as P. luinuscula (Bin- 

ney), a wide-spread American species. 

9. lleli.x vortex. (Pfr.) Southern Florida and West Indies. 

10. ** niicrodonta. (Desh.) Bahama Islands. 

11. ** appressa. (Ssiy.) Virginia and adjacent States : perhaps in- 

troduced into Beimuda. 

12. ** pulchella. (Miill.) Europe; very close to If. minuta (Say) of 

the United States. Introduced into Ber- 
muda? 

13. ** ventricosa. (l)rap.) Azores, Canary Islands, and South Europe. 

14. Bulimulus nitidulus. (Pfr.) Cuba, Hayti, etc. 

15. Stenogyra octona. (Ch.) West Indies and South America. 

IG. Cionclla acicula. (Miill.) Florida, New Jersey, and Europe. 



Chap. XII.] BERMUDA. 257 

1 7. Pupa pelliicidn. (l*fi*.) West Indies, generallr. 

18. '* Barbndensis. (Ffr.) Bnrbndoes? 

19. '* Jamaicensis. (C.B. Ad.). Jamaica. 

20. Ilelicina convexa. (Pfr.) Barbuda. 

Mr. Bland indicates only four species as certainly peculiar to 
Bermuda, and another sub-fossil species ; while one or two of the 
remainder are indicated as doubtfully identical with those of 
other countries. We have thus at least one fourth of the land 
shells peculiar, while almost all the other productions of the isl- 
ands are identical with those of the adjacent continent and isl- 
ands. This corresponds, however, with what occurs generally 
in islands at some distance from continents. In the Azores only 
one land bird is peculiar out of eighteen resident species; the 
beetles show about one eighth of the probably non-introduced 
species as peculiar, the plants about one twentieth ; while the 
land shells have about half the species peculiar. This difference 
is well explained by the much greater difficulty of transmission 
over wide seas, in the case of land shells, than of any other ter- 
restrial organisms. It thus happens that when a species has 
once been conveyed it may remain isolated for unknown ages, 
and has time to become modified by local conditions unchecked 
by the introduction of other specimens of the original type. 

Flora of Bermuda. — Unfortunately, no good account of the 
plants of these islands has yet been published. Mr. Jones, in 
his paper " On the Vegetation of the Bermudas," gives a list of 
no less than 480 species of flowering plants; but this number 
includes all the culinary plants, fruit-trees, and garden flowers, 
as well as all the ornamental trees and shrubs from various 
parts of the world which have been introduced, mixed up with 
the European and American weeds that have come with ag- 
ricultural or garden seeds, and the really indigenous plants, in 
one undistinguished series. It appears, too, that the late gov- 
ernor, Major-general Lefroy, " has sown and distributed through- 
out the islands packets of seeds from Kew, representing no less 
than 600 species, principally of trees and shrubs suited to sandy 
coast soils'' — so that it will be more than ever difficult in fut- 
ure ycai*s to distinguish the indigenous from the introduced 
vegetation. 

17 



18LANU J-lFli. 



tPAHT li. 



From tlio researches of Dr. Eeiii and Mr. Moseley there ap- 
pear to lje about two hundred and fifty flowering plants in a, wild 
state, and of tboBe Mr. Moscley thinks less than half are indig- 
enous. The majority are tropical and West Indian, while oth- 
ers are common to tiie isouthecn States of North America ; the 
former class having been largely brought by means of the Gulf 
Stream, the latter by the agency of birds or by winds. Mr. 
Jones tells ua that the currents bring numberless objects ani- 
mate and inanimate from the'Caribbean Sea, including the seeds 
of trees, shrubs, and other plants, wiiich arc continually cast 
ashore and Bometimcs vegetate. The soapberry-tree {Sapindus i 
saponaria) has been actually observed to originate in this way. 

Professor Oliver informs me that ho knows of no undoubtedly 
distinct 8])ecie8 of flowering plants peculiar to Bermuda, though 
there are some local forms of continental species^instancing 
Siayvinchium.jBerjn'udlanum, and Rhus toxicodendron. Tliere 
arcjhowever, two ferns — an AdiantumandaNephrodinm— which 
are unknown from any other locality, and this rendere it prob- 
able that some of the flowering plants are also peculiar. The 
juniper, which is so conspicuous a feature of the islands, is said 
to be a West Indian species (Junijwug Jiarhadeneis) found in 
Jamaica and the Bahamas, not the North American red cedar; 
but there seems to be still some doubt about this common plant. 

Mr. Moseloy, who visited Bermuda in tlie ChaUengev, has well 
explained the probable origin of the vegetation. The large 
number of West Indian plants is, no doubt, due to the Gulf 
Stream and constant surface drift of warm water in this direc- 
tion, while others have been brought by the annual cyclones 
which sweep over the intervening ocean.- The great number of 
American migratory birds, including large flocks of the Ameri- 
can golden plover, Mith ducks and other aquatic species, no doubt 
occasionally bring seeds, either in the mud attached to their feet 
or in their stomachs.' As these causes are either constantly in 
action or recur annually, it is not surprifiing that almost all the 
species should be unchanged owing to the frei^nent intercroeaing 



" Ni'ies oil ilio Vegclniion of Bermiidn," !■? II. N. Mo»ele», Journal 0/ the Lin- 
% A'oclXy.Vol. XIV., Botanv, p. 317. 



Chap. XII. J BERMUDA. 259 

of freshly arrived specimens. If a competent botanist were 
thoroughly to explore Bermuda, eliminate the species introduced 
by human agency, and investigate the source from whence the 
others were derived and the mode by which they had reached 
so remote an island, we should obtain important information as 
to the dispersal of plants, which might afford us a clew to the 
solution of many ditficult problems in their geographical distri- 
bution. 

Concluding Remarks, — The two groups of islands we have 
now been considering furnish us with some most instructive 
facts as to the power of many groups of organisms to pass over 
from seven hundred to nine hundred miles of open sea. There 
is no doubt whatever that all the indigenous species have thus 
reached these islands, and in many cases the process may be seen 
going on from year to year. We find that, as regards birds, mi- 
gratory habits and the liability to be caught by violent storms 
are the conditions which determine the island population. In 
both islands the land birds are almost exclusively migrants ; and 
in both the non-migratory groups — wrens, tits, creepers, and 
nuthatches — are absent ; while the number of annual visitors is 
greater in proportion as the migratory habits and prevalence of 
storms afford more cfiicient means for their introduction. 

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

Plants are represented by a considerable variety of orders and 
genera, most of which show some special adaptation for dispersal 
by wind or water, or through the medium of birds ; and there is 
no reason to doubt that, besides the species that have actually 
established themselves, many others must have reached the isl- 
ands, but were not suited to the climate and other physical con- 
ditions, or did not find the insects necessary to their fertiliza- 
tion. 

If, now, we consider the extreme remoteness and isolation of 



260 ISLAND LIFE. [Past IL 

these islands, their small area, and comparatively recent origin, 
and that, notwithstanding all these disadvantages, they have ac- 
quired a very considerable and varied flora and fauna, we shall, 
I think, be convinced that, with a larger area and greater an- 
tiquity, mere separation from a continent by many hundred 
miles of sea would not prevent a country from acquiring a very 
luxuriant and varied flora, and a fauna also rich and peculiar 
as regards all classes except terrestrial mammals, amphibia, and 
some groups of reptiles. This conclusion will be of great im- 
portance in many cases where the evidence as to the exact ori- 
gin of the fauna and flora of an island is less clear and satis- 
factory than in the case of the Azores and Bermuda. 



CiiAP.XIlI.] THE GALAPAGOS ISLANDS. 261 



CHAPTER XIII. 

THE GALAPAGOS ISLANDS. 

Position and Physical Features. — Absence cf Indigenous Mammalia and Amphibia. 
— Reptiles. — Birds. — Insects and Land Shells. — ^The Keeling Islands as Illustrat- 
ing the Manner in which Oceanic Islands are Peopled. — Flora of the Galapagos. 
— Origin of the Flora of the Galapagos. — Concluding Hemarks. 

The Galapagos differ in many important respects from the 
islands we liave examined in our last chapter, and tbe differ- 
ences are such as to hare affected tlie whole chamcter of their 
animal inhabitants. Like the Azores, they are volcanic, but they 
are much more extensive, the islands being both larger and more 
numerous; while volcanic action has been so recent and exten- 
sive that a large portion of their surface consists of barren lava- 
fields. They are considerably less distant from a continent than 
either the Azores or Bermuda, being about six hundred miles 
from the west coast of South America and a little more than 
seven hundred from Veragua, with the small Cocos Islands in- 
tervening; and they are situated on the equator instead of being 
in the north temperate zone. They stand upon a deeply sub- 
merged bank, the lOOOfathom line encircling all the more im- 
portant islands at a few miles' distance, whence there appears to 
be a comparatively steep descent all round to the average depth 
of that portion of the Pacific, between 2000 and 3000 fathoms. 

The whole group occupies a space of about three hundred by 
two hundred miles. It consists of five largo and twelve small 
islands ; the largest (Albemarle Island) being about eighty miles 
long and of very irregular shape, while the four next in impor- 
tance — Chatham, Indefatigable, James, and Narborough Islands 
— are each about twenty-five or thirty miles long, and of a 
rounded or elongate form. The whole are entirely volcanic, 
and in the western islands there are numerous active volcanoes. 



ISLAND LIFE. 



[lU. 



Unlike the otliei" groups of islands we Lave been conBidcriiig;, 
these are situated iu a comparatively calni sea, ^heie storms are 
of i-are occurrence and even strong winds almost unknown. 
Tliej are traversed by ocean ctirrenla which are strong and con- 




stant, flowing towai-da the northwest from the coast of Pern J 
and these physical conditions have had a powerful inflnence oikl 
the animal and vogotable forms by which tlio islands arc novl 
inhabited. The Galapngos have also, during three centnne8,4 
been frequently visited by EiiropeanB, and were long a favoi 



^ L-B*!-. XIII.] THE GALAPAGOS ISLANDB. 26S ^M 


^M reeort of buccaneers an<l traders, wlio found an ample sapiAy 
^H food in the large tortoises whidi abound there; and to tlie 
^1 vieiu WD may peiliapa trace the introdnction of some anima 
^H whose presence it is otherwise difflcult to account for. The veg 


t 
e 

s 




MJ iH • act Ml _ 










^^^^k <)WC^^^^^^^^^^^^^^^^^^^^H 






7^^^^^^^^^^^^^|Hi|^^^^^^^^^^^^Hi 






^^^^^^^^^^^^^^r r,<>,aMi:coH :. ^^^^^^^^^^^^M 






J^^K f: '^^^^L 






^^m/r'-:^^"^^^'' ^1 


















«»r o. iB« 0.1..-.OO.. 


^H Tl<« liitht tint ilioug n deplh of leu thxn 1000 ru1hon». ^M 
^^H The Ggurei iliow ibe ilciHh in fiHbomi. ^H 


^^M tation ie generally ecunty, but etill amply enfficlent for tlie enp- ^| 
^1 port of a considei-able ainonnt of animal life, as shown by the H 


^^1 cattle, horses, nssee, goats, pigs, doge, and cats n'liieh now niii ^| 
^H wild iu some of the islands. H 
^^M Absence of Indigeno»ia Mammalia and Amphibia. — As in ail ^H 
^H other oceanic islands, we find hero no truly indigenous mam- ^M 



264 ISLAND LIFE, [I'jinT U, 

malia, for llioiigli tlierc is a inonse of tlie American genus 
Ilesperomys, wliicli differs Eomewlint from any known species, 
we can ImiiJIy consider tliis to be indigenous; iirat, because tlieso 
creatures have been little studied in South America, and there 
may yet be many nndescribed species; and, in the second place, 
because, even had it been introduced by some European or native 
vessel, there is ample time in two or tlii-ee Imndred years for the 
very different conditions to liave established a marked diversity 
in the charactere of the species. This is the more probable be- 
cause there is also a true rat of the Old World genua Mus, which 
is said to differ slightly from any known species; and as this 
genus is nut a native of the American continents, wo are siii'e 
that it mnsl have been recently introduced into tlio Galapagos. 
Tlicre can be little doubt, therefore, that the islands are com- 
pletely destitute of truly indigenous mammalia; and frogs and 
toads, the only tropical representatives of the Amphibia, are 
equally unknown. 

J^fj)(ileii,-^Rept\\e5, however, which at first sight appear as 
nnsnited as mammals to pass over a wide expanse of ocean, 
abound in the Galapagos, though the species are not very nu- 
merous. TJiey consist of land -tortoises, lizai'ds, and finakee. 
The toi'toisea consist of two pecul lar species, Testudo micr&phyes, 
found in most of the islands, and T. Ahingdoni, recently dis- 
covered on Abingdon Island, na well as one extinct species, T. 
ephij^piuin, found on Indefatigable Island. Tiicso are all of 
very large size, like the gigantic tortoises of tlie Masearene 
Islands, fi'om which, however, tliey differ in structural eliarae- 
Icrs; and Dr. Giintlier believes that they have been originally 
derived from the American continent.' Considering the well- 
known tenacity of life of these animals, and the large number 
of allied forms which have aquatic or eubaquatie habits, it is 
not a very extravagant supposition that some ancestral form, 
carried out to sea by a flood, was oueo or twice safely drifted as 
far fls the Galapagos, and thus originated the races which now 
inhabit them. 



n (lio CoUeciion of ilie Biiiiuli 



Chap. XIII.] THE GALAPAGOS ISLANDS. 265 

The lizards are five in number — a peculiar species of gecko, 
PhyUodaetylxis Galapagerisis^ and four species of the American 
family Iguanidse. Two of these are distinct species of the genus 
Liocephahis, the other two being large, and so very distinct as to 
bo classed in peculiar genera. One of these is aquatic and found 
in all the islands, swimming in the sea at some distance from the 
shore, and feeding on seaweed ; the other is terrestrial, and is 
confined to the four central islands. These were originally de- 
scribed by Mr. Bell as Amhlyrhynchua cristatus and A. subana- 
taius ; they were afterwards placed in two other genera, Tra- 
chycephalns and Oreocephalus (see British Museum Catalogue 
of Lizards) ; while in a recent paper by Dr. Giinther the marine 
species is again classed as Amblyrhynchus, while the terrestrial 
form is placed in another genus, Conolophus. 

How these lizards reached the islands we cannot tell. The 
fact that they all belong to American genera or families indi- 
cates their derivation from that continent, while their being all 
distinct species is a proof that their arrival took place at a re- 
mote epoch, under conditions perhaps somewhat different from 
any which now prevail. It is certain that animals of this order 
have some means of crossing the sea not possessed by any other 
land vertebrates, since they are found in a considerable number 
of islands which possess no mammals nor any other land reptiles; 
but Avhat those means are has not yet been positively ascertained. 

It is unusual for oceanic islands to possess snakes, and it is 
therefore somewhat of an anomaly that two species are found 
in the Galapagos. Both are closely allied to South American 
forms, and one is hardly different from a Chilian snake, so that 
they indicate a more recent origin than in the case of the liz- 
ards. Snakes, it is known, can survive a long time at sea, since 
a living boa-constrictor once reached the Island of St. Vincent 
from the coast of South America, a distance of two hundred 
miles by the shortest route. Snakes often frequent trees, and 
might thus be conveyed long distances if carried out to sea on 
a tree uprooted by a flood such as often occurs in tropical cli- 
mates, and especially during earthquakes. To some such acci- 
dent we may perhaps attribute the presence of these creatures 
in the Galapagos, and that it is a very rare one is indicated by 



266 ISLAND LIFE. [Pabt II. 

the fact that only two species have as yet succeeded in obtaining 
a footing there. 

Birds. — We now come to the birds, whose presence here'may 
not seem so remarkable, but which yet present features of inter- 
est not exceeded by any other group. Fifty-seven species of 
birds have now been obtained on these islands, and of these 
thirty-eight are peculiar to them. But all the species found else- 
where, except one, belong to the aquatic tribes or the waders, 
which are pre-eminently wanderers, yet even of these eight are 
peculiar. The true land birds are thirty-one in number, and all 
but one are entirely confined to the Galapagos ; while more than 
half present such peculiarities that they are classed as distinct 
genera. All are allied to birds inhabiting tropical America, some 
very closely ; while one — the common American rice-bird, which 
ranges over the whole northern and part of the southem conti- 
nent — is the only land bird identical with those of the main- 
land. The following is a list of these land birds taken from Mr. 
Salvin's memoir in the Transactions of the Zoological Society 
for the year 1876 : 

TuKDlD-fi. 

.. , / This nnd the two allied species are related 

2. melanotus > , ,, • y- ■% w- , • j 

3. ** parvulus ) ^ 

Mniotiltid^. 

4. Dendraca aureola Closely allied to the wide - ranging Z>. 

a^stiva. 

HlRUNDIXIDiE. 

ii. Prognc concolor Allied to P. purpurea of North and South 

America. 

C<EREBIDiE. 

6. Certhidea olivacea > A peculiar genus allied to the Andean 

7. ** fusca > genus Coi»Vo»/rMW/. 

Frinoillid^ic. 



8. Geospiza magnirostris. 

strenua 

dubia 



9. 




10. 




11. 




12. 




13. 




H. 


i * 


15. 


44 



/ortis ^ A distinct genus, huL allied to the Soiiili 



nebulosa 
fuliginosa . . 
parvula .... 
dentiroitris 



American genus Guiraca. 



Chap.XIIL] the GALAPAGOS ISLANDS. 267 

16. Cactomis icandens 

17. '* assimilis . «• i * .i i ^ 

,o iL 'jf J ' >A genus allica to the last. 

1 8. " Abingdoni ' 

19. ' " pallida 

20. Camarhynchus psittaculas., 

Q,^ J J . (A very pecnliar genus allied to iVisorAjfii- 

""* ,, ^ '^ff ** "f I ckus of the TFest coast of Peru. 

23. ' ' prosthemelas 

21. " Habeii 

ICTKBIDJE. 

2o. Dolichonyx oryzivora Ranges from Canada to Paraguay. 

TTRAMMIDiE. 

26. Pyrocephalus nanus Allied to P, rubineua of Ecuador. 

27. Myiarchus magniroslris Allied to West Indian species. 

COLUMBIDiE. 

28. Zenaida Galapagotntii A peculiar species of a South American 

genus. 

FALCOMIDiE. 

20. Butto Galapagoensis A buzzard of peculiar coloralion. 

STRIGIDiE. 

30. Aslo Galapagoensis Hardly distinct from the wide-spread A. 

brachyotus. 

31 . Strix punctatissima Allied to S.Jlammea, but quite distinct. 

We have here every gradation of difference, from perfect 
identity with the continental species to genera so distinct that 
it is difficult to determine with what forms they are most nearly 
allied ; and it is interesting to note that this diversity bears a 
distinct relation to the probabilities of, and facilities for, migra- 
tion to the islands. The excessively abundant rice-bird, which 
breeds in Canada and swarms over the whole United States, mi- 
grating to the West Indies and South America, visiting the dis- 
tant Bermudas almost every year, and extending its range as far 
as Paraguay, is the only species of land bird which remains 
completely unchanged in the Galapagos ; and we may therefore 
conclude that some stragglers of the migrating host reach the 
islands sufficiently often to keep up the purity of the breed. 
Next, we have the almost cosmopolite short-eared owl {Asio 
brac/iT/otus), which ranges from China to Ireland, and from 
Greenland to the Strait of Magellan, and of this the Galapagos 



ISLAND LIFE. 



[PuiTlL 



bird 16 probably only one of the nuineroua varieties. Tlie little 
wood-warbler {Dendrwca amvola) is closely allied to a species 
which ranges over the whole of North America and as far eonth 
as New Granada. It has also been occasionally met with in Ber- 
muda, an indication that it Las considerable powei-s of flight and 
cndm-ance. The more distinct species — as the inocking-thrushes 
(Mimus), the tyrant fly-catchers (Pyroeephaliis and Myiarchns), 
and the ground-dove (Zenaida) — are all allied to non-migratory 
species peculiar to tropical America, and of a mure restricted 
range; while the distinct genera are allied to South American 
groups of finches and sugar-birds which have usually restricted 
ranges, and whose habits are such as not to render them likely 
to be carried out to sea. The remote nncesti'al forms of these 
birds which, owing to somo exceptional canses, reached the tial- 
apagos, have thus remained nninflnenced by later migrationti, 
and have iu consequence been developed into a variety of dis- 
tinct types adapted to the peculiar conditions of existence under 
which they have been placed. Sometimes the different species 
thus formed are conlined to one or two of the islands only, as 
the two species of Certhides, which are divided between the isl- 
ands, hut do not appear ever to occur together. Mimus parvulus 
19 confined to Albemarle Island, and M. tr-ifaaciatus to Charles 
Island J C'actornis paU'ula to Indefatigable Island, and C. Abinff- 
doni to Abingdon Island. 

Now all these phenomena arc strictly consistent with the tlie- 
ory of the peopling of the islands by accidental migrations, if 
we only allow them to have existed for a sufficiently long peri- 
od ; and the fact that volcanic action has ceased on many of the 
islands, as well as their great extent, would certainly indicate a 
considerable antiquity. 

■The great difference presented by the birds of these islands 
as compared with those of the equally remote Azoi-es and Ber- 
mudas is snfiSciently explained by the difference of cliinatal con- 
ditions. At the Ualapagos there are none of those periodic 
storms, gales, and hurricanes which prevail in the North Atlan- 
tic, and which every year carry some straggling biids of Europe 
or North America to the former islands; while, at the same 
time, the majority of the tropical American birds are non-migra- 



W»'%'i 



Chap. XIII.] THE GALAPAGOS ISLANDS. 261> 

tory, and thus afford none of the opportunities presented by the 
countless hosts of migrants which pass annually northward and 
southward along the European and especially along the North 
American coasts. It is strictly in accordance with these different 
conditions that we find in one case an almost perfect identity 
with, and in the other an almost equally complete diversity 
from, the continental species of birds. 

Insects and Land Shells. — The other groups of land animals 
add little of importance to the facts already referred to. The 
insects are very scanty; the most plentiful group, the beetles, 
only furnishing about thirty-five species, belonging to twenty- 
nine genera and eighteen families. The species are almost all 
peculiar, as are some of the genera. They are mostly small 
and obscure insects, allied either to American or to world-wide 
groups. The CarabidflB and the Heteromera are the most abundant 
groups, the former furnishing six and the latter eight species.* 

* The following list of the beetles yet known from the Gnlnpngos shows their 
scanty proi)ortiuiis and accidental character; the thirty-seven siiecies bch)nging to 
thirty-one genera and eighteen families. It is taken from Mr. Waterhouse's enu- 
meration in the Proceeding of the Zoological Society for 1877 (p. 81) : 

Carabid^. Nkcropraoa. 

Feronia cahuhoides. Acribis semitix-entris. 

** insiiiaiis. Phalacriis Darwinii. 



i( 



Gahipagoensis. Dermestes vulpinus. 
Amblygnnilius obscuricomis. CcRCOUoNiDiE. 

Solcnophorns Galapagoensis. Otiorhynchus cnneiformis. 

Notapims Galapagoensis. Anchouus Galapag«»en»is. 

Dyti8cid.£. Loxoicounia. 

Eunectes occidenUilis. Ebuiia araabilis. 

Malacodkrms. Hetkromrba. 

Ablechrus Darwinii. Stomion lielopoides. 
Coryneies rufii^s. ** lasvigiitum. 

Bos'tricliiia nnciniatus. Ammophorus obscums. 

Lambllicornks. ** Cookaoni. 

^ . I , . bifoveatns. 

Copns 1"«"»«. PedonoBces Galupag.Hsnsis. 
Orycies Galapagoensis. ., pubeiceus. 

hLATKRiDiC. Phalerin manicata. 
Physorhinus Galapagoensis. Anthribidje. 

AciliuH incisus. Ormiscus vaiiegaius. 
Copelatiis Gahipagoensis. Phytopiiaoa. 

Pai.picornes. Piabrotica limbata, 

Tro])i8tcniiis lateralis. Docema Galapagoensis. 

Philhydriis sp. Longitiirsus lunatus. 

STAPIlYLlNIDiB, SkcURIPALPES. 

Creophilus villosus. Scymnus Galapagoensis. 



arc 



ISLAND LIFE. 



[P*M II. 



The land shells are not abundant — about twenty in all, most 
of them peculiar species, but not otherwise remarkable. The 
observation of Captain Collnet, quoted by Mr, Darwin in hie 
"Journal," that drift-wood, bamboos, canes, and the nuts of a 
palm are often ^vaslied on the soutlieastern shores of the isl- 
ands, furnisiies an excellent clew to the manner in which many 
of the insects and land shells may have rciiched the Galapagos. 
Whirlwinds also have been known to carry quantities of leaves 
and other vegetable debris to great heiglits in the air, and these 
might bo tlien carried away by strong upper currents and 
dropped at great distances, and with tlieni small insects and 
niollusca, or their eggs. We must also remember that volcanic 
islands are subject to subsidence as well as elevatiou ; and it is 
quite possible tliat during the long period the Galapagos have 
existed soine islands may liavo intervened between them and 
the coast, and have served as stepping-stones by which the pas- 
sage to them of various organisms would be greatly f.icilitated. 
Sunken banks, the relics of such islands, are known to exist in 
many parts of the ocean, and countless others, no doubt, remain 
undiscovered. 

Tfie Keding Ixlamh as lUustratiny the Maimer in which 
Oceanic /elands are Peopled. — That such causes as have been 
here adduced are those by which oceanic islands have been peo- 
pled is further shown by the condition of equally remote islands 
which we know are of comparatively recent origin. Sncb are 
the Keeling or Cocos Islands in the Indian Ocean, situated 
about the same distance from Sumatra as the Galapagos from 
South America, but mere coral reefs, supporting abundance of 
cocoa-nut palms as their chief vegetation. These islands were 
visited by Mr. Darwin, and tlieir natural history enrefnily ex- 
amined. The only mammals are rata brought by a wrecked 
vessel, and said by Mr. Wateriiouse to be common EnglisJi i-ats, 
"but smaller and more brightly coloi-ed;" so that wc have here 
an illustration of how soon a difference of race ia established 
under a constant and uniform difference of conditions. There 
are no true land birds, bnt there are snipes and rails, both ap- 
parently common Malayan species. Ilcptiles are represented by 
one small lizard, but no account of this is given in tlie " 2!oology 



Chap.XIIL] the GALAPAGOS ISLANDS. 271 

of the Voyage of the Beagle," and we may therefore conclude 
that it was an introduced species. Of insects, careful collect- 
ing only produced thirteen species belonging to eight distinct 
orders. The only beetle was a small Elater, the Orthoptera 
were a Gryllus and a Blatta ; and there were two flies, two ants, 
and two small moths, one a Diopsea which swarms everywhere 
in the eastern tropics in grassy places. All these insects were, 
no doubt, brought either by winds, by floating timber (which 
reaches the islands abundantly), or by clinging to the feathers 
of aquatic or wading birds; and we only require more time, to 
introduce a greater variety of species, and a better soil and more 
varied vegetation, to enable them to live and nmltiply, in order 
to give these islands a fauna and flora equal to those of the Ber- 
mudas. Of wild plants there were only twenty species, belong- 
ing to nineteen genera and to no less than sixteen natural fami- 
lies, while all were common tropical shore plants. These islands 
are thus evidently stocked by waifs and strays brought by the 
winds and waves ; but their scanty vegetation is mainly due to 
unfavorable conditions — the barren coral rock and sand, of which 
they are wholly composed, together with exposure to sea-air, be- 
ing suitable to a very limited number of species which soon 
monopolize the surface. With more variety of soil and aspect 
a greater variety of plants would establish themselves, and these 
would favor the preservation and increase of more insects, birds, 
and other animals, as we And to be the case in many sniall and 
remote islands.* 

' Junn Fernandez is a good cxnmple of a smaU island wliich, with time and favor- 
able conditions, has acquired a tolerably rich and highly peculiar flora and fauna. It 
is situated in 34^ 8. lat., 400 miles from tlie coast of Chili, and, so far as facilities for 
the transport of living organisms arc concerned, is by no means in a favorable posi- 
tion, for the ocean currents come from the southwest in a direction where there is 
no land but the antarctic continent, and the prevalent winds are also westerly. No 
doubt, however, there are occasional storms, and there may have been intermediate 
islands; but its chief advantages are, no doubt, its antiquity and its varied surface, 
ortering many chances for the preservation and increase of whatever plants and ani- 
mals have chanced to reach it. The island consists of basalt, greenstone, and other 
ancient rocks, and, though only about twelve miles long, its mountains are three 
thousand feet high. lOnjoying a moist and temperate climate, it is especially adapted 
to the growth of ferns, which are very abundant ; and as the spores of these plants 
are as fine as dust, and very easily carried for enormous distances by winds, it is not 



am 



JSLANO XJITE. 



[PuTlL 



Flora of t/us Galapagos. — The plants of tlicae ielands are eo 
niiicli moro nnmeroiis tlian the known animals, even including 
the insects, they have been so carefully stndiad hy eminent 
botanists, and their relations throw so much light on tlie past 
history of the gi'oup, that no apology is needed for giving a 
brief outline of iho peculiarities and affinities of the fioi-a. The 
stnteincnta we sliall make on this subject will be taken from the 
memoir of Sir Joseph Hooker in the Limiixan Transactions for 
1851, founded on Mr. Darwin's collections, and a later paper by 
N. J, Andersson in the Linnmt of 1861, embodying more recent 
discoveries. 

Tlie total number of flowering plants known at the latter date 
was 332, of which 174 were peculiar to the islands, while 158 
wore common to other countries. Of these latter abont 20 have 
been introduced by man, while the remainder arc all natives of 
some part of America, tliougli abont a tliird part are species of 
wide range extending into botli hemispheres. Of those confined 
to America, 42 are found in both the northern and southern 
continents, 21 are confined to South America, while 20 are 
found only in North America, the West Indies, or Mexico. 
This equality of North American and South American Epecics 
in the Galapagos is a fact of great significance in connection 
with the observation of Sir Joseph Hooker, that the peculiar 
species are allied to the plants of temperate America or to those 
of the high Andes, while the non-peculiar species are mostly 



turpriaing rlinl there arv ttrcnty-foiir spcciet on (he i<i1nnd, nliiln llic remote period 
when il Hot leceireJ im vegetnlioii may ba inilieiiled b; llio Tiict llmt fuiir oC ilia 
■|ie('l(u nil] qiiiie peculiar. The Mine genernl charncter pervades the whole flurn 
nnil r»iiiiit. For so sroiill an Islniid it is rii:h, coninimng a conaiilcrnUe number of 
Boweriiig pliiiits four inie lnn<l birilt, nhnnt fifty upecie* of insecta, nnd Iwenir ti( 
binil fihallR. AlntiiBi nil lliete ticliiiig to Soiilli Ainericnii genem, nnd a Inrge prapui- 
liun RTe SiHilli Ameticnn 8|>etic8i but sereral of llie ])lnnu nnd insects, liair ilia 
birdi, and the n hole oT ilia Innd ilicUn nre peviilinr. 'J'hia seems to indicnie thni ilia 
■nemtg uf imiisniiMioii (reiti fiinnerlr grcmer (hiu) titty me nniv, nnd tlini in th* can 
oTIniid ahells ni>i>e hnve tteeii iiitrodupod fur to lung a |«Hod that nil hnve become 
modidod into Uistlitcl furmi, or have been prcaerved on the island nhile tliey hava 
bocomc exiliiei on tlie coniinenl. For n delailod nxiitninnlion of ilia cuimes wliieh 
hav« led to ihe modi lien Hnii Dflhe hiimtniiiQ- birds of Jiian Fernandea. see the an- 
ihor'i "Trupirid Nniure,"p. 110; white n Rvncral lu-coiini ofilic faDiinorilie isUtid 
Ugivon ill Ilia " Geogrnphical Uiirribuiion of Anintiil*," Vol, 11., p. tU. 



Chap.XIH.] TUE GALAPAGOS ISLANDS. 273 

such as inliabit the Iiotter regions of the tropics near the level 
of the sea. He also observes that the seeds of this latter class 
of Galapagos plants often liave special means of transport, or 
belong to groups whose seeds are known to stand long voyages 
and to possess great vitality. Mr. Bentham, also, in his elaborate 
account of the Compositse,* remarks on the decided Central 
American or Mexican affinities of the Galapagos species, so that 
we may consider this to be a thoroughly well-established fact. 

The most prevalent families of plants in the Galapagos are 
the Compositae (40 species), Gramineae (32 species), Leguminos© 
(30 species), and Euphorbiaceae (29 species). Of the Compositae 
most of the species, except such as are common weeds or shore 
plants, are peculiar, but there are only two peculiar genei*a allied 
to Mexican forms and not very distinct ; while the genus Lipo- 
chaeta, represented here by a single species, is only found else- 
where in the Sandwich Islands, though it has American affin- 
ities. 

OrUjin of the GoLapagos Flora. — These facts are explained by 
the past history of the American continent, its separation at va- 
rious epochs by arms of the sea uniting the two oceans across 
what is now Central America (the last separation being of re- 
cent date, as shown by the identical species of fishes on both 
sides of the isthmus), and the influence of the glacial epoch in 
driving the temperate American flora southwai*d along the 
mountain plateaus.' At the time when the two oceans were 
united, a portion of the Gulf Stream may have been diverted 
into the Pacific, giving rise to a current, some part cf which 
would almost certainly have reached the Galapagos, and this 
may have helped to bring about that singular assemblage of 
West Indian and Mexican plants now found there. And as we 
now believe that the duration of the last glacial epoch in its suc- 
cessive phases was much longer than the time which has elapsed 
since it finally passed away, while throughout the Miocene epoch 
the snow-line would often be lowered during periods of high 
eccentricity, we are enabled to comprehend the nature of the 

* Journal of the Linnaan Society^ Vol. XIII., Botnny, p. 556. 
' ** Geographical Distribution of Animnla," VoL II., p. SL 

18 



97+ 



ISLAND LIFR, 



Tir. 



canses wliieli may Jiave lot! to tlie islands being etoeked with 
those northern or eubalpine types which are so ehamctcristic a 
feature of that portion of the Galapagos flora which conei&ts of 
peculiar species. 

On the whole, the flora agrees with the fauna in indicating a 
moderately remote origin, great isolation, and changes of condi- 
tlona affording facilities for the introdnction of organisma from 
various parts of the Ameriean coast, and oven from the West 
Indian Islands and Gulf of Mexico. Aa in the case of the birds, 
tl)e several islands differ considerably in their native plants, 
many species being limited to one or two islands only, while 
others extend to several. This is, of course, what might be ex- 
pected on any theory of their origin ; because, even if the whole 
of the islands had once been united and afterwards separated, 
long-continued isolation would often load to the differentiation 
of species, while the varied conditions to be found upon islands 
differing in sizo and altitude as well as in Insuriance of vegeta- 
tion would often lead to the extinction of a species on one isl- 
and and its preservation on another. If the several islands had 
been eijually well explored, it might be interesting to see wheth- 
er, as in the case of the Azores, the number of species diminished 
in those more remote from the coast; but, unfortunately, our 
knowledge of the productions of the various islands of tlie group 
in exceedingly nne<]ual, and, except in those cases in which re\> 
resentative species inhabit distinct islands, we have no certainty 
on the subject. All the more interesting problems in geograph- 
ical distribution, however, arise from the relation of the fauna 
and flora of the group as a whole to those of the surrounding 
continents ; and we shall therefore, for the moat part, confine our- 
selves to this aspect of the question in our discussion of tlic phe- 
nomena presented by oceanic or continental islands. 

Conclvding lianarkv. — The Galapagos offer an instructive 
contrast with the Azores, showing how a difference of conditions 
that might be tliought unimportant may yet produce very strik- 
ing results in the forms of life. Although the Galapagos are 
much nearer a continent than the Azores, the number of speelea 
of i)lant8 common to the continent Is mucli Jess in the former 
case than in the latter, and thia is still more prominent a clmrnc- 



Chap. XIII.] THE GALAPAGOS ISLANDS. 275 

teristic of the insect and the bird fauna. This difference has 
been shown to depend almost entirely on the one archipelago 
being situated in a stormy, the other in a calm, portion of the 
ocean ; and it demonstrates the preponderating importance of 
the atmosphere as an agent in the dispei*sal of birds, insects, and 
plants. Yet ocean currents and surface drifts are undoubtedly 
efficient carriers of plants, and, with plants, of insects and shells, 
especially in the tropics ; and it is probably to this agency that 
we may impute the recent introduction of a number of common 
Peruvian and Chilian littoral species, and also at a more remote 
period of several West Indian types when the Isthmus of Pana- 
ma was submerged. 

In the case of these islands we see the importance of taking 
past conditions of sea and land and past changes of climate into 
account, in order to explain the relations of the peculiar or en- 
demic species of their fauna and flora ; and we may even see an 
indication of the effects of climatal changes in the Northern 
Hemisphere, in the north temperate or Alpine affinities of so 
many of the plants, and even of some of the birds. The relation 
between the migratory habits of the biixis and the amount of 
difference from continental types is strikingly accordant with 
the fact that it is almost exclusively migratory birds that annu- 
ally reach the Azores and Bermuda ; while the corresponding 
fact that the seeds of those plants which are common to the 
Galapagos and the adjacent continent liave all — as Sir Joseph 
Hooker states — some special means of dispersal is equally intel- 
ligible. The reason why the Galapagos possess four times as 
many peculiar species of plants as the Azores is clearly a result 
of the less constant introduction of seeds, owing to the absence 
of storms; the greater antiquity of the group, allowing more 
time for specific change; and the influence of cold epochs and 
of alterations of sea and land in bringing somewhat different sets 
of plants at different times within the influence of such modi- 
fied winds and currents as might convey them to the islands. 

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



ISLAND LIFE. 



CHAPTER SIV. 

ST. IlKLESA. 

1*0*111011 mid I'hj'siciil Feaiures of Si, Ueleiin.— Change Effected by ILiiropoan Oc- 
cupftlion.— Tlie liisecia of St. Helena. — C'-uIeojireru. — reculinrJLlea and Oiigin iif 
the Coleoplei'A of St. Helena. — Land SJielli of Si. Helenn. — ALcence of Fresli- 
w«ier Oripinunis. — Xnilve Vegeiation of St. Uelenn. — The Belnliona of tli« Sr. 
Ileleiiit Cumposiia. — CODcludliig Itemarka on St. Uelenn. 

In order to illustrate as completely as possible tiie peculiar 
phenomena of oceanic ielanda, we will next examine the organie 
productions of St. Helena, and of the Sandwich lelande, since 
these combine in a higher degree than any other spots upon tlio 
globe extreme isolation from all more extensive lands ^vitll a 
tolerably rich fauna and fiora whose peculiarities are of surpass- 
ing interest. Both, too, have received considerable attention 
from naturaiiets; and though much still remains to be done in 
the latter group, our knowledge is sufficient to enable lis to ar- 
rive at many interesting results. 

I'ou'dion and Physical Features of St. Helena. — This island 
is situated nearly in the middle of the South Allantic Ocean, 
being more than 1100 miles from the coast of Africa, and 1800 
from South America. It is about ten miles long by eight wide, 
and is wholly volcanic, consisting of ancient basalts, lavas, and 
other volcanic products. It is very mountainous and rugged, 
bounded, fur the most part, by enormous precipices, and rising to 
a, height of 2700 feet above the sea-level. An ancient crater, 
about four miles across, is open on the south side, and its north- 
ern rim forms the highest and central ridge of the island. 
Many other bills and peaks, liowever, are more than two thou- 
sand feet high, and a considerable portion of the snvface consists 
of a rugged plateau, having an elevation of about fifteen hundred 
to two thousand fcot. Everything indicates that St, Helena is 



SYS 



ISJJ&ND LIFB. 



[Pabi IL 



ail isolateii volcanic lunsa built up from the depths of tlic ocean. 
Mr. WoUastoii remarkB, " Tliere are the strongest reasons for 
believing that the area of St. Helena was never -cenj much larger 
than it is at present — the comparatively shallow sea-sou ntl in t[3 
within about a mile and a half from the shore revealing an 
ahniptly delincd ledge, beyond which no bottoin is reached at a 
depth of 250 fathoms; so that the original basaltic mass, wiiich 
was gradiially piled up by means of successive eruptions from 
beneath the ocean, would appciir to Jiavo its limit definitely 
marked out by this suddenly terminating submarine cliff — the 
space between it and the existing coast-lUie being reasonably re- 
ferred to that slow process of disintegration by which the ishmd 
has been reduced, tlirongh the eroding action of the elements, 
to its present dimensions." If we add to this that between the 
island and the coast of Africa, in a southeasterly direction, is a 
profound oceanic gnlf known to reach a depth of 286U fulhoms, 
or 17,100 feet, while an ei^iially deep, or perhaps deeper, ocean 
extends to the west and sontliwcst, we shall bo satisfied that St. 
Helena is a true oceanic island, and that it owes none of its pe- 
ciilinritics to a former union with any continent or other distant 
land. 

Chawje Efftdfid hy European Occupation. — When firat dis- 
covered, 37S years ago, St. Helena was densely covered with a 
Inxiiriant forest vegetation, the trees overhanging the seaward 
precipices and covering every part of the surface with an ever- 
green mantle. This indigenous vegetation lias been almost 
wholly destroyed ; ami although an immense number of foreign 
plants have been introduced, and have more or less completely 
established themselves, yet the general aspect of llio island is 
now so barren and forbidding that some persons find it diflicnlt 
to believe that it was once all green and fertile. The cause of 
the change is, however, very easily explained. Tlie rich soil 
formed by decomposed volcanic rock and vegetable deposits 
could only be retained on the steep slopes so long us it was pro- 
tected by the vegetation to whicli it in great part owed its origin. 
When this was destroyed, the heavy tropical rains soon washed 
away the soil, and has left a vast expanse of bare rock or sterile 
clay. This irreparable destruction was cansed, in the first pLice, 



Chap. XIV.] ST. HELENA. 279 

by goats, which were introduced by the Portuguese in 1513, 
and increased so rapidly that in 1588 they existed in thousands. 
These animals are the greatest of all foes to trees, because they 
eat oflE the young seedlings, and thus prevent the natural resto- 
ration of the forest. They were, however, aided by the reckless 
waste of man. The East India Company took possession of the 
island in 1651, and about the year 1700 it began to be seen that 
the forests were fast diminishing, and required some protec* 
tion. Two of the native trees, redwood and ebony, were good 
for tanning, and, to save trouble, the bark was wastefully stripped 
from the trunks only, the remainder being left to rot ; while in 
1709 a largo quantity of the rapidly disappearing ebony was 
used to burn lime for building fortifications ! By the MS. rec- 
ords quoted in Mr. Melliss's interesting volume on St. Helena,* 
it is evident that the evil consequences of allowing the trees to 
be destroyed were clearly foreseen, as the following passages 
show : " We find the place called the Great Wood in a flourish- 
ing condition, full of young trees, where the hogs (of which there 
is a great abundance) do not come to root them up. But the 
Great Wood is miserably lessened and destroyed within our 
memories, and is not near the circuit and length it was. But wo 
believe it does not contain now less than fifteen hundred acres 
of fine woodland and good ground, but no springs of water but 
what is salt or brackish, which we take to be the reason that that 
part w^as not inhabited when the people first chose out their 
settlements and made plantations; but if wells could be sunk, 
which the governor says he will attempt when we have more 
hands, we should then think it the most pleasant and healthiest 
part of the island. But as to healthiness, we don't think it will 
hold so if the wood that keeps the land warm were destroyed ; 
for then the rains, which are violent here, would carry away 
the upper soil, and, it being a clay marl underneath, would pro- 
duce but little ; as it is, we think in case it were enclosed it 
might be greatly improved. . . . When once this wood is gone, 
the island will soon be ruined. . . . We viewed the wood's 



* ** St. Helena: a Pliysical, Ilistoricnl, and Topograpliical Description of the Isl- 
and," etc., by John Charles Melliss, F.G.S., etc. London, 1875. 



ISLAND LIFK 



[PiBTlI. 



end wbicli joins the Honorable Company's plantation called the 
Hutts, but the wood is so destroyed that the beginning of the 
Great Wood is now a whole mile beyond that place ; and all the 
Boil being washed away, that distance is now entirely barren" 
(MS, llccords, 1716). In 1709 the governor reported to the 
Court of Uirectoi-B of the East India Company that tlio timber 
was rapidly disappearing, and that the goats should be destroy- 
ed for the preservation of the ebony wood, and because the isl- 
and was suffering from droughts. The reply was, "The goats 
are not to be destroyed, being more valuable than ebony." Thus, 
through tiic gross ignorance of those in power, the last oppor- 
tunity of preserving the peculiar vegetation of St. Ilelena, and 
preventing the island from becoming the comparatively rocky 
desert it now is, was allowed to pass away.' Even in a mere 
pecuniary point of view, the error was a fatal one, for in the next 
eentnry (iu 1810) another governor reports the total destruction 
of the great forests by the goats, and that in coneequeueo the 
cost of importing fuel for government use was £2729 7s. 8d. for 
a single year I- About this time large numbers of European, 
American, Australian, and South African plants wero imported, 
and many of these ran wild and increased so rapidly as to drive 
out and exterminate mncli of the relics of tho native Hora; so 
that now English broom, gorso and brambles, willows and pop- 



I Mr. Mnrali. in hia intorwlidg work entitled "The Earth as MoJlflcd by Hiiuuin 
Aciiini"(p. Gl). tlimreranrki mi tlia c^Tect of browsing qiisd raped a in dcsi roving nnd 
cliecking woody vegotation : " I am convinced ihot htetu noald BOon cover many jinrts 
of ihB Arnbiun and Africnn dcwns if mnii and domestic animals, eHpeciallr ilie gont 
nnd the cAmel, vtMi banitlied from llicm. The hnrd paliiie and inngue nnd Btrong 
teeth and jnwi of Ibis latter qundniped enable liim lo brcnk off and mnstlente tough 
nndibomybrancliesnslnrgenBihBflneer. Ileisparticulnrlyfondof iheamollertwigF, 
tenvea, nndaeed-podiof lliG^anfond olUer aonclni, whicfi.likeihe American Kobinin, 
lUriie well on dry and sandy loils ; and he ipnrM no tree the branclies of wliich are 
within hi] readi, except, if I lemcnibcr right, t)ic tamarisk that producei mnnnn. 
Young trees iproul plentifully around ilid «|irine> |fid along the winter wBter-eouraei 
of tho desert, and Iheae are just ih« ha[ting-»tai<on> of the cnravana and tlicir roulo* 
of travel. In the shade of these iroci, antinni gmases and perennial ebrubs thool tip, 
but ma mown down by the hungry coiiIe of the Itedouin ns fust as they grow. A 
few yean of undialurbcd vegetation would siiHIce to cover such points with (trores, 
and thioe would Bnidually extend tliemMlve* over soils where now scarcely nny greeu 
thing lint the bitter colocynih nnJ the poifonons fox-glove is ever seen." 



Chap. XIV.] ST. HELENA. 281 

lars, and some common American, Cape, and Australian weeds, 
alone meet the eye of tlie ordinary visitor. These, in Sir Joseph 
Hooker's opinion, render it absolutely impossible to restore the 
native flora, which only lingers in a few of the loftiest ridges 
and most inaccessible precipices, and is rarely seen except by 
some exploring naturalist. 

This almost total extirpation of a luxuriant and highly pecul- 
iar vegetation must inevitably have caused the destruction of a 
considerable portion of the lower animals which once existed on 
the island, and it is rather singular that so much as has actually 
been discovered should be left to show us the nature of the 
aboriginal fauna. Many naturalists have made small collections 
during short visits, but we owe our present complete knowledge 
of the two most interesting groups of animals — the insects and 
the land shells — mainly to the late Mr. T. Vernon Wollaston, 
who, after having thoroughly explored Madeira and the Cana- 
ries, undertook a voyage to St. Helena for the express purpose 
of studying its terrestrial fauna, and resided for six months 
(1875-76) in a high central position, whence the loftiest peaks 
could be explored. The results of his labors are contained in 
two volumes,* which, like all that he wrote, aiX3 models of accu- 
racy and research, and it is to these volumes that we are indebt- 
ed for the interesting and suggestive facts which we here lay 
before our readers. 

Insects — Coleoptera. — The total number of species of beetles 
hitherto observed at St. Helena is 203 ; but of these no less 
than 74 are common and wide-spread insects, which have cer- 
tainly, in Mr. Wollaston's opinion, been introduced by human 
agency. There remain 129, which are believed to be truly ab- 
origines, and of these all but one are found nowhere else on the 
globe. But, in addition to this large amount of specific pecu- 
liarity (perhaps unequalled anywhere else in the world), the 
beetles of this island are equally remarkable for their generic 
isolation, and for the altogether exceptional proportion in which 
the great divisions of the order are represented. The species 
belong to thirty-nine genera, of which no less than twenty-five 



1 (t 



Coleoptera Sanct» Helenic," 1877; "Testocea Atlnntica," 1878. 



ISLAND LIFE, 



[PiBlU. 



are peculiar to tlie island; and mnny of these are siicli isoluted 
forms that it k impossililo to linJ their allies ia any particular 
country. Still more rciniirkahle is thu fact that more than two 
thirds of the whole nimiher of itidigenoua sjjeciijs are Ithyiicoph- 
ora, or weevils, while more than two tifths (tifty-fonr speuies) be- 
long to one family, the Cossonidie. Now, although the Jlhyn- 
cophora are an immensely numerons group and always form a 
large portion of the insect population, they nowhere else ap- 
proach such a proportion as this. For example, in Madeira they 
form one si.xth of the whole of the iudigeuous Coleoptera, in 
the Azores less than one tenth, and in Britain one Beventli. 
Even more interesting is the fact that the twenty genera to 
which these insects belong are every one of them peculiar to 
tlie island, and in many cases have no near allies elsewhere, so 
that we cannot hot look on this group of beetles as forming the 
most characteristic portion of the ancient insect fauna. Now, 
as the groat majority of these are wood-borers, and all arc closely 
attached to vegetation, and often to particular epecics of plants, 
we might, as Mr. Wollaston well observes, dcduco the former 
Inxuriant vegetation of the island from the great preponderance 
of this group, oven had wo not positive evidence that it was 
at no distant epoch densely forest-chid. We will now proceed 
briefly to indicate the numbers and peculiaiitiea of each of the 
families of liectles which enter into the St, Helena fauna, taking 
them, not in systematic order, hut according to their importance 
in the island. 

1. ItuyNL-QPuoBA. — This great division includes the weevils 
and allied groups, and, as above stated, exceeds in number of 
species all the other beetles of tlio island. Four families are 
represented; the Cossonidie. with fifteen peculiar genera com- 
prising fifty-four species, aud one minute insect {Sl^noscdts hy- 
Uuitoi<Je») forming a peculiar genus, hut ■which has been found 
also at the Cape of Good IJope. It is therefore impossible to 
say of which country it is really a native, or whether it is indig- 
enous to both, aud dates back to the remote period when St. 
Helena received its early immigrants, All tho Coesonida; are 
found in the highcEt and wildest parts of the island where the 
native vegetation still lingers, aud many of them are only found 



CiLiP. XIV.] ST. HELENA. 283 

in the decaying steins of tree-ferns, box-wood, arborescent Com- 
positae, and otlier indigenous plants. They are all pre-eminently 
peculiar and isolated, having no direct affinity to species found 
in any otlier country. The next family, the Tanyrhynchidae, has 
one peculiar genus in St. Helena, with ten species. This genus 
(Xesiotes) is remotely allied to European, Australian, and Ma- 
deiran insects of the same family : the habits of the species are 
similar to those of tlie Cossonidce. The Trachyphloeidse are repre- 
sented by a single species belonging to a peculiar genus not very 
remote from a European form. The Anthribidae, again, are high- 
ly peculiar. There are twenty-six species, belonging to three 
genera, all endemic, and so extremely peculiar that they form 
two new sub-families. One of the genera, Acarodes, is said to 
bo allied to a Madeiran genus. 

2. Geodepiiaoa. — These are the terrestrial carnivorous beetles, 
very abundant in all parts of the world, especially in the tem- 
perate regions of the Northern Hemisphere. In St. Helena 
there are fourteen species, belonging to three genera, one of 
which is peculiar. This is the llaplothorax BurcheUii^ the largest 
beetle on the island, and now very rare. It resembles a large 
black Carabus. There is also a peculiar Calosoma, very distinct, 
though resembling in some respects certain African species. 
The rest of the Geodephaga, twelve in number, belong to the 
wide-spread genus Bembidium ; but they are altogether peculiar 
and isolated, except one, which is of European type, and alone 
has wings, all the rest being wingless. 

3. IIetkeomera. — This group is represented by three peculiar 
genera containing four species, with two species belonging to 
European genera. They belong to the families Opatridte, Mor- 
dellid^e, and Anthicidse. 

4. Bkaciiyelytka. — Of this group there are six peculiar spe- 
cies, belonging to four European genera — Homalota, Philonthus, 
Xantholinus, and Oxytelus. 

5. Priocerata. — The families Elateridre and Anobiidae are 
each represented by a peculiar species of a European genus. 

0. PiiYTopiiAOA. — There are only three species of this tribe, 
belonging to the European genus Ix)ngitarsu8. 

7. Lamellicornis. — Here are three species, belonging to two 



964 



ISLAND LIFE. 



[P*B 



genera. Oiic is a peculiar species of Trox, allied to South Afri- 
can forms; tbe other two belong to the pecnliar genus Meliseiiis, 
which Mr. AVollaston considers to be remotely allied to Austra- 
lian insects. 

8. PsErDo-TRraERi. — Here mg liave the fine lady-bird Chtlo- 
vienus lunata, also found in Africa, but apparently indigenous 
in St. Helena ; and a peculiar species of Eusestes, a genua only 
found elsewhere in Madeii'a. 

9. TiucuopTERVGiD^. — Tliese, the minutest of beetles, are rep- 
resented by one species of the European and Madeiran genus 
Ptinella. 

10. Neckophaga, — One indigenous apeeioe of Cryptophnga 
inhabits St. Helena, and this is said to be very closely allied to 
a Cape species. 

Peculiarities arid Origin of the Cohoptera of St. Helena. — 
We see that the great mass of the indigenous species are not 
only peculiar to the island, but so isolated in their characters as 
to show no close affinity with any existing insects ; while a small 
number (about one third of the whole) have some relations, 
though often very remote, with species now inhabitiug Europe, 
Madeira, op South Africa. These facts clearly point to the very 
great antiquity of the insect fauna of St. Helena, which has al- 
lowed time for the modification of the originally introduced spe- 
cies, and their special adaptation to the conditions prevailing in 
this remote island. This antiquity is also shown by the remark- 
able specific modification of a few types. Thus the whole of 
the Cossonidffi may be referred to three types, one species only 
(Ilexacoptiig femtgineva) being allied to the European Cossoni- 
dte, though forming a distinct genus ; a group of three genera 
and seven species j'eniolely allied to the Htf^noscelis hylastoides, 
which occnrs also at the Capo : while a group of twelve genera 
with forty-six species have their only (remote) allies in a few 
insects widely scattered in South Africa, New Zealand, Europe, 
and the Atlantic islands. In like manner, eleven species of 
Bembidium form a group by themselves; and the HeteroTuera 
form two groups — one consisting of three genera and species of 
Opatridffi allied to a type found in Madeira; the other, Antbico- 
des, altogether peculiar. 



Chap. XIV.] ST. HELENA. 285 

Now each of these types may well be descended from a single 
species which originally reached the island from some other 
land ; and the great variety of generic and specific forms into 
which some of them have diverged is an indication, and to some 
extent a measure, of the remoteness of their origin. The rich 
insect fauna of Miocene age found in Switzerland consists mostly 
of genera which still inhabit Europe, with others which now in- 
habit the Cape of Good Hope or the tropics of Africa and South 
America ; and it is not at all improbable that the origin of the 
St. Helena fauna dates back to at least as remote, and not im- 
probably to a still earlier epoch. But if so, many diflBculties in 
accounting for its origin will disappear. We know that at that 
time many of the animals and plants of the tropics of North 
America, and even of Australia, inhabited Europe ; while during 
the changes of climate which, as we have seen, there is good 
reason to believe periodically occurred there would be much 
migration from the temperate zones towards the equator, and 
the reverse. If, therefore, the nearest ally of any insular group 
now inhabits a particular country, we are not obliged to suppose 
that it reached the island from that country, since we know that 
most groups have ranged in past times over wider areas than 
they now inhabit. Neither are we limited to the means of trans- 
mission across the ocean that now exist, because we know that 
those means have varied greatly. During such extreme changes 
of conditions as are implied by glacial periods and by warm polar 
climates, great alterations of winds and of ocean currents are in- 
evitable ; and these are, as we have already proved, the two great 
agencies by which the transmission of living things to oceanic 
islands has been brought about. At the present time the south- 
east trade-winds blow almost constantly at St. Helena, and the 
ocean currents flow in the same direction, so that any transmis- 
sion of insects by their means must almost certainly be from 
South Africa. Now there is undoubtedly a South African ele- 
ment in the insect fauna, but there is no less clearly a European, 
or at least a north temperate element, and this is very difficult 
to account for by causes now in action. But when we consider 
that this northern element is chiefly represented by remote ge- 
neric affinitj', and has therefore all the signs of great antiquity, 



ISLASD LIFK 



CPiarlL 



we find n po3sil>!e meaos of accounting for it. "We liave Been 
that during early Tertiary times an ahiiogt tropical climate ex- 
tended fur into tlio Northern Hemisphere, and a temperate cli- 
mate to the arctic regionB. But if at this time (as is not im- 
probable) the antarctic regions were as mtich ice-clad as they are 
now, it is certain that an enormous change must have been pro- 
duced in the winds. Instead of a great diiference of tempera- 
ture between each pole and the equator, the difference would be 
mainly between one hemisphere and the other, and this might so 
disturb the trade-winds aa to bring St. Helena within the south 
temperate region of storms — a position corresponding to that of 
the Azores and Madeira in the North Atlantic, and thus subject 
it to violent gales from all points of the compass. At tiiis re- 
mole epoch, the monntains of e'|iiatoriaI Africa may have been 
more extensivo than they are now, and may have served as in- 
termediate stations by which some northern insects may Imvc 
migrated to the Sonthern Hemisphero. 

We mnat reniember,also,that these peculiar forms are said to 
be northern only because their nearest allies are now found in 
the North Atlantic islands and Southern £urope; but it is not 
at all improbable that tliey are really wide-spread Miocene types 
which have been preserved mainly in favorable insular stations. 
They may, therefore, have originally reached St. Helena from 
Southern Africa, or from some of the Atlantic islands, and may 
have been convoyed by oceanic currents aa well as by winds.' 

'OiiPeteiinaiin'iiinnpcifAfrici»inthenewoiiilionofSiielBr'ii''Uainl-AHiia"(IB79), 
iha Inland ot A>cen«ii>ii it Bhonn ns aenicd on o mucli Inrger nnil ilia1lu\ver lubinit- 
rine bank tlinii Si. Helenn. Tho lOOO-fiitliom line ronnil Aicension enrlii««s nn oiril 
■)sce ITO miles tong by 70 wide, nnd even ilie ai)0-riuhom lino one over GO milea 
tongi nnd it i> thererure probable thnt n much larger Ulnnd onfe occupied thU 
■ite. Now Aiwensiun is nearly eqnidisinm lictween Si. Helena nnd Liberi*. and »ucU 
Mti itland might liKva saned oi nn iniermeiJiiite ainlian through nliith many o( the 
immigrntiu lo SL Helena pnsseJ. As the dislancei aro hnrdly grsnter limn in th« 
CMS of the Axoi'e!!, ihia removes whatever difficult]' mnj' hnvo been fell of ihe poui- 
hilii; of (uijr organiRins reaehing so remole an island. The prewnt Island ot Aieen- 
tlon is prolinbly only Ihs summit of a linge volcanic maas, nnd any remnant ot tbo 
original faimn nnd florn it might linve pi'escn'cd inny hnve been dettrorcd by gitKt 
volcanic sruptioni. Mr. Dnrnin collecicd some miissos of tufa which were found lo 
ba mainly orgnnic, coninining, be^iides remiiini; of fii»li-iviiier infiinorin, ihe uliccnns 
lissiie of plunli ! In tlio liglii of ibc great exieni of tbo lubmnrinc bnnk on ivhieli 



Chap. XIV.] ST. HELENA. 287 

This 18 the more probable, as a large proportion of the St. Helena 
beetles live even in the perfect state within the stems of plants 
or trunks of trees, while the eggs and larvae of a still larger 
number are likely to inhabit similar stations. Drift-wood might 
therefore be one of the most important agencies by which these 
insects reached the island. 

Let us now see how far the distribution of other groups sup- 
ports the conclusions derived from a consideration of the beetles. 
The Hemiptera have been studied by Dr. F. Buchanan White; 
and though far less known than the beetles, indicate somewhat 
similar relations. Eight out of twenty-one genera are peculiar, 
and the thirteen other genera are, for the most part, widely dis- 
tributed, while one of the peculiar genera is of African type. 
The other orders of insects have not been collected or studied 
with sufficient care to make it worth while to refer to them in 
detail ; but the land shells have been carefully collected and mi- 
nutely described by Mr. Wollaston himself, and it is interesting 
to see how far they agree with the insects in their peculiarities 
and affinities. 

Land Shells of St, Helena, — The total number of species is 
only twenty-nine, of which seven are common in Europe or the 
other Atlantic islands, and are, no doubt, recent introductions. 
Two others, though described as distinct, are so closely allied to 
European forms that Mr. Wollaston thinks they have probably 
been introduced and have become slightly modified by new con- 
ditions of life ; so that there remain exactly twenty species which 
may be considered truly indigenous. No less than thirteen of 
these, however, appear to be extinct, being now only found on 
the surface of the ground or in the surface soil in places where 
the native forests have been destroyed and the land not culti- 
vated. These twenty peculiar species belong to the following 
genera : Hyalina (3 sp.), Patula (4 sp.), Bulimus (7 sp.), Subulina 
(3 sp.), Succinea (3 sp.) ; of which one species of Hyalina, three 
of Patula, all the Bulirai, and two of Subulina are extinct. Tlie 

the island 8tnnds, Mr. Darwin's remark, that **we may feel sure that at some former 
epoch the climate and productions of Ascension were very different from what they 
are now," has received a striking confirmation. (See ** Naturalist's Voyage round 
the World," p. 405.) 



388 ISUUID LIF£. [PaiitIL 

three HyaliDas arc allied to European species, but all tlie rest ap- 
pear to be iiiglily peculiar, and to liavu no near allies with the 
species of any other country. Two of tlio Bulimi {B.auris -eul- 
pinm and B. Darwinianui) are said to somewhat resemble Bm- 
zilian, Kew Zealand, and Solomon Island forms, while neither 
JJuInitUB nor Suceinea occurs at all in the Madeira group. 

Omitting the speeies that have probably been introdnced Ity 
human agency, we have here indications of a somewhat recent 
immigration of European types which may perhaps he referred 
to the glacial period; and a much more ancient immigration 
from unknown lands, which must certainly date back to Miocene, 
if not to Eocene, times. 

Absence of Ft'csh-waUr Organisms. — A singular phenomenon 
is the total absence of indigenous aquatic forms of life in St. 
Helena. Not a single water-beetle or fresh-water shell has been 
discovered; neither do there seem to be any water-plants in tlie 
Btreama except the common water-ci-ess, one or two species of 
Cyperus, and the Australian laapis proll/era. The same ab- 
sence of fresh-water shells characterizes the Azores, where, how- 
ever, there is one indigenous water-beetle. In the Sandwich 
Islands also recent observations refer to the absence of water- 
beetles, though here there are a few fresh-water shells. It would 
appear, therefore, that the wide distribution of the same generic 
and specific forms which so generally characterizes fresh-water 
organisms, and which has been so well illustrated by Mr. Darwin, 
has its limits in the very remote oceanic islands, owing to causes 
of wLiicli we are at present ignorant. 

The other classes of animals in St. Helena need occupy us lit- 
tle. Tiiere are no indigcnons mammals, reptiles, fresh-water 
I £sltes, or true land birds; but there is one species of wader — a 
Binall plover {j£gialitis •Sanctm ffdejid) very closely allied to u 
species found in South Africa, but presenting certain differences 
which entitle it to the rank of a ])cculiar species. The plants, 
however, are of especial interest from a geographical point of 
view, and we must devote a few pages to their consideration as 
supplementing the scanty materials afforded by the animal life, 
thus enabling us bettor to undei-stand the biological relations 
and probable history uf the island. 



Chap. XIV.] ST. HELENA. 2S9 

Native Vegetation of St, Helena. — Plants have certainly more 
varied and more effectual means of passing over wide tracts of 
ocean than any kinds of animals. Tlieir seeds are often so mi- 
nute, of such small specific gravity, or so furnished with downy 
or winged appendages, as to be carried by the wind for enor- 
mous distances. The bristles or hooked spines of many small 
fruits cause them to become easily attached to the feathers of 
aquatic birds, and they may thus be conveyed for thousands of 
miles by these pre-eminent wanderers ; while many seeds are so 
protected by hard outer coats and dense inner albumen that 
months of exposure to salt water does not prevent them from 
germinating, as proved by the West Indian seeds that reach the 
Azores or even the west coast of Scotland, and, what is more to 
the point, by the fact stated by Mr. Melliss, that large seeds 
which have floated from Madagascar or Mauritius round the 
Cape of Good Hope have been tlirown on the shores of St. 
Helena and have then sometimes germinated ! 

We have therefore little difficulty in understanding how the 
island was firet stocked with vegetable forms. IVhen it was so 
stocked (generally speaking) is equally clear. For, as the pecul- 
iar Coleopterous fauna, of which an important fragment remains, 
is mainly composed of species which are specially attached to 
certain groups of plants, we may be sure that the plants were 
there long before the insects could establish themselves. How- 
ever ancient, then, is the insect fauna, the flora must be more 
ancient still. It nmst also be remembered that plants, when 
once established in a suitable climate and soil, soon take posses- 
sion of a country, and occupy it almost to the complete exclusion 
of later immigrants. The fact of so many European weeds hav- 
ing overrun New Zealand and temperate North America may 
seem opposed to this statement, but it really is not so. For in 
both these cases the native vegetation has first been artificially 
removed by man and the ground cultivated; and there is no 
reason to believe that any similar effect would be produced by 
the scattering of any amount of foreign seed on ground already 
completely clothed with an indigenous vegetation. We might 
therefore conclude, a priori^ that the fiora of such an island as 
St. Helena would be of an excessively ancient type, preserving 

19 



390 



ISLAND LIFE. 



[PabtIL 



for lis in a slightly modified form exainplee of tlie vegetation 
of tbo globe at the time when the island first rose above tbe 
ocean. Let us see, then, what botanists tell ns of its character 
and affinities. 

The truly indigenons flowering plants are abont fifty in num- 
ber, besides twenty-eix ferns. Forty of the former and ten of 
the latter are absolutely peculiar to the island, and, ag Sir Josepli 
Ilooker tells iia, " with scarcely an exception, cannot be i-egardcd 
as very close specific allies of any other plnnta at all. Seven- 
teen of them belong to peculiar gener,i, and of the others all 
differ so markedly as species from their congeners that not one 
comes under the category of being an insular form of a conti- 
nental species." Tlie affinities of this flora are, Sir Joseph 
Hooker thinks, mainly African and especially South African, aa 
indicated by the presence of the genera Phylica, Pelargonium, 
Mesoinbryantbeiuiun, Oteospermum, and Wableiibergia, which 
are eminently cliaracteristie of eoutliern extratropical Africa. 
Tbe sixteen ferns which are not peculiar are common either to 
Africa, India, or America, a wide range sufficiently explained by 
the dust -like spores of ferns, capable of being carried to un- 
known distances by the wind, and the great stability of their 
generic and specific forme, many of those found in tbe Miocene 
deposits of Switzerland being hardly distinguishable from liv- 
ing species. This shows tliat identity of species of ferns be- 
tween St. Uelcna and distant countries does not necessarily im- 
ply a recent origin. 

Thu Helation of the SI. Ilehma dmiposit^.—Ia an elaborate 
paper on the Composite,' Mr. Bentham gives ns some valuable 
remarks on the affinities of the seven endemic species belonging 
to the genera Commidendron, Melanodeudron, Petrobium, and 
Pisiadia, which form so important a portion of the exieting 
flora of St. Helena. He saya, "Although nearer to Africa than 
to any other continent, those composite denizens wliicli bear ev- 
idence of the greatest antiquity have their affinities, for the most 
part, in South America, while the colonists of a more recent 
character are South African. . . . Commidendron and Melano- 

' "Noies oil the Clnsiiflcalioii. lllitoiT, mid Geogrnphknl Distribmion of Compo- 
tits," Jtmraai »/ Iht I-Uiufai, S«riely. Vol, XIU., p. Ji03 (1878), 



Chap. XIV.] ST. HELENA. 291 

dendroQ are among the woody Asteroid forms exemplified in 
the Andine Diplostephiam, and in the Australian Olearia. Pe- 
trobium is one of three genera, remains of a group probably of 
great antiquity, of wliich the two others are Podanthus ia Chili 
and Astemma in the Andes. The Pisiadia is an endemic spe- 
cies of a genus otherwise Mascarene or of Eastern Africa, pre- 
senting a geographical connection analogous to that of the St. 
Helena Melhanise ' with the Mascarene Trochetia." 

Whenever such remote and singular cases of geographical af- 
finity as the above are pointed out, the first impression is to im- 
agine some mode by which a communication between tlie dis- 
tant countries implicated might be effected; and this way of 
viewing the problem is almost universally adopted, even by nat- 
uralists. But if the principles laid down in this work and in 
my "Geographical Distribution of Animals" are sound, such a 
course is very unphilosophical. For, on the theory of evolution, 
nothing can be more certain than that groups now broken up 
and detached were once continuous, and that fragmentary groups 
and isolated forms are but the relics of once wide-spread types, 
which have been preserved in a few localities where the phys- 
ical conditions were especially favorable, or where organic com- 
petition was less severe. The true explanation of all such re- 
mote geographical affinities is that they date back to a time 
when the ancestral group of which they are the common de- 
scendants had a wider or a different distribution ; and they no 
more imply any closer connection between the distant countries 
the allied forms now inhabit than does the existence of living 
EquidiB in South Africa and extinct Equidse in the Pliocene 
deposits of the Pampas imply a continent bridging the South 
Atlantic to allow of their easy communication. 

Concluding Remarks on St Helena, — The sketch we have now 
given of the chief menribers of the indigenous fauna and flora 
of St. Helena shows that by means of the knowledge we have 
obtained of past changes in the physical history of the earth, and 
of the various modes by which organisms are conveyed across 



' The Melhnnioe comprise the two finest timber trees of St. Helena, now nlmost 
extinct — the red-wood iind native ebonj. 



292 ISLAND LIFE. [Part II. 

the oceaD, all the more important facts becomo readily intelligi- 
ble. We have here an island of small size and great antiquity, 
very distant from every other land, and probably at no time 
very much less distant from surrounding continents, which be- 
came stocked by chance immigrants from other countries at 
some remote epoch, and which has preserved many of their 
more or less modified descendants to the present time. When 
first visited by civilized man, it was in all probability far more 
richly stocked with plants and animals, forming a kind of nat- 
ural museum or vivarium in which ancient types, perhaps dating 
back to the Miocene period, or even earlier, had been saved from 
the destruction which has overtaken their allies on the great 
continents. Unfortunately, many — we do not know how many — 
of these forms have been exterminated by the carelessness and 
improvidence of its civilized but ignorant rulers ; and it is only 
by the extreme ruggedness and inaccessibility of its peaks and 
crater-ridges that the scanty fragments have escaped by which 
alone we are able to obtain a glimpse of this interesting chapter 
in the life-history of our earth. 



Chap. XV.] THE SANDWICH ISLANDS. 293 



CHAPTER XV. 

THE SANDWICH ISLANDS. 

Position and Physical Features. — Zoolog}' of the Sandwich IsUnds. — Bird«. — Ke|>- 
tiles. — Land Shells. — Insects. — Vegetation of the Sandwich Islands. — Peculiar 
Features of the Hawaiian Flora. — Antiquity of the Hawaimn Fauna and Flora. — 
Concluding Ohsenrations on the Fauna and Flora of the Sandwich It^Iands. — Gen- 
eral Remarks on Oceanic Ishinds. 

The Sandwich Islands are an extensive group of large islands 
situated in the centre of the North Pacific, being 2350 miles 
from the nearest part of the American coast — the Bay of San 
Francisco — and about the same distance from the Marquesas and 
the Samoa Islands to the south, and the Aleutian Islands a little 
west of north. They are therefore wonderfully isolated in mid- 
ocean, and are only connected with the other Pacific islands by 
widely scattered coml reefs and atolls, the nearest of which, how- 
ever, are six or seven hundred miles distant, and are all nearly des- 
titute of animal or vegetable life. The group consists of seven 
large inhabited islands besides four rocky islets; the largest, 
Hawaii, being seventy miles across, and having an area of 3800 
square miles — being somewhat larger than all the other islands 
together. A better conception of this large island will be formed 
by comparing it with Devonshire, with which it closely agrees 
both in size and shape, though its enormous volcanic mountains 
rise to nearly 14,000 feet. Three of the smaller islands are 
each about the size of Hertfordshire or Bedfordshire, and the 
Avhole group stretches from northwest to southeast for a distance 
of about 350 miles. Though so extensive, the entire archipelago 
is volcanic, and the largest island is rendered sterile and com- 
paratively uninhabitable by its three active volcanoes and their 
wide-spread deposits of lava. 

The ocean depths by which these islands are separated from 
the nearest continents are enormous. North, east, and south, 



294 



ISLAND LIFE. 



UPABt U. 



fionndingB have been obtained a little over or under 3000 fatli- 
oms, and these profound deeps extend over a large part of the 
North Pacific. We may be quite sure, tliei-efore, that the Sand- 
wich Islands have during their wiiole existence been as com- 
pletely severed from the great contiucuts as they are now ; but 
on the west and south there is a possibility of more extensive 







islands having existed, serving ns stepping-stones to the island 
groups of the mid-Pacitic. This is indicated by a few widely 
scattered coral islets, around which extend considenihie areas of 
less depth, varying from 2oO to 1000 fathoms, and which mat/ 
therefore indicate the sites of submerged islands of considerable 
extent. When we consider that cast of New Zealand and New 
Caledonia all the larger and loftier islands are of volcanic origin, 



_ki^ 



Chap. XV.] 



THE SANDWICH ISLANDS. 



20G 



witli no traee of any ancient Btratificd rocks (except, perhaps, in 
tlie Marquesas, where, according tu Jules Marcou, gniiiito and 
gnoiiis are Baid to occur), it seenm probable that the ianunicrabic 
coral reefs and atolls, which occur in groups on deeply Bnb- 

nicrged banks, mark the silea of bygone vulfauic ielandu similar 



I 





to tliotio which now exist, bnt whidi, nflcr becoming extinct, 
have been lowered op desti-oyed by denudation, and tinally, by 
snbsidence of tlio earth's emat, have altogether diitappeartd, ex- 
cept where their sites are indicated by the upward-growing coral 
recfa. If this view is correct, we should give np all idea of there 



ISLAND LIFE. 



[Past II. 



ever having been a Pacific contineut, but should look upon that 
vast ocean as having from the i-einotest geological epoche been 
the scat of volcanic forces, which from its profound depths have 
gradnallj built up the islands which now dot its surface, as well 
as many others which have suuk beneath its waves. The nnm- 
ber of islands, as well as the total quantity of land stii'face, uiay 
sometimes have been greater than it is now, and may thus have 
facilitated the transfer of organisms from one group to another, 
and, more rarely, even from the Aniericnn, Asiatic, or Australian 
continent. Keeping these various facts and considerations in 
view, we may now proceed to examine the fauna and flora of 
the Sandwich Islands, and dlscQSs the special phenomena they 
present. 

Zoology of the Sanihcich Jifandif: Birds. — It need hardly be 
said that indigenous manjiualiu arc quite unlcnown in the Sand- 
wich Islands, the most interesting of the higher animals being 
the birds, which arc tolerably nnmcrons and highly peculiar. 
Many aquatic and wading birds wlucii range over tho whole Pa- 
cific visit these islands, twenty-four epecies having been ob- 
served ; but even of these five are peculiar — a coot, Fulka ala! ,- 
H, inoor-hen, Oallin'ul.a Handvichenniii f & rail with rudimentary 
wings, I'cnmtla viiUei ; and two ducks, Ana8 Wyvilllana and 
Scmicla fiantlvichen»i«. The birds of jirey are also great wan- 
derers. Four have been found in the islands — the short-eared 
owl, Oliu imt'AyoiiM, which ranges over the greater part of the 
globe, but ii< here said to resemble the variety found in Chili 
and the Galapagos; the harn-o-wl, Stnx Jlamniea, oi a variety 
common in t!io Pacilic; a peculiar sparrow-hawk, Aevipil^ir JIa- 
xcaii ; and Uuteo sotitarius, a buzzard of a peculiar species, and 
colored so as to resemble a hawk of the American enb-family 
Polyborinte. It is to be noted that the genus Buteo abounds in 
America, but is not found in the Pacific; and this fact, com- 
bined with the remarkable coloration, renders it almost certain 
that this peculiar species is of American origin. 

Coming now to the Passeres, or true perehing-birds, we find 
sixteen species, all peculiar, belonging to ten genera, all but one 
of which are also peculiar. The following is a list of tlicse ex- 
tremely interesting birds: 



CuAP. XV.] 



THE SANDWICH ISLANDS. 



297 



I. 


MusciCAFiDA (Flycatchers). 


1. 


Chasiempis Sandvichensis, 


Ma 


Phceornis obscura. 


[r. 


Melipuaoidjb (Honeysackers). 


3. 


Mohoa nobilis. 


4. 


" braccata. 


r». 


** apicalis. 


6. 


Chatoptila angusti}*luma. 




III. Drepanididje. 


7. 


Drepanis coccinea. 


8. 


** rosea. 


9. 


** Jlava. 


10. 


*^ tanguinea. 



Drepanididfe — Continued. 

1 1. Hendgnathus olivaceus, 

12. ** obacunu. 

13. <' /aici(f««. 

14. Lorops coccinea, 

15. ** Aurea. 
] 6. Loxioides bailloni, 

1 7. Psittirottra psittacea, 

18. Fringilla anna (recently de- 
scribed, perhaps belongs 
also to this group). 

IV. CoRviDJE (Crows). 

19. Cor V us Hawaiensis, 

Taking the above in the order here given, we have, first, two 
peculiar genera of flycatchers, a family confined to the Old 
World, but extending over the Pacific as far as the Marquesas 
Islands. Next we have two peculiar genera (with four species) 
of honeysuckers, a family confined to the Australian region, and 
also ranging over all the Pacific islands to the Marquesas. We 
now come to the most important group of birds in the Sandwich 
Islands, comprising five peculiar genera, and eleven or twelve 
species, which are believed to form a peculiar family allied to 
the Oriental flower-peckers (Diceidse), and perhaps remotely to 
the American greenlets (Vireonidse) or tanagers (Tanagridae). 
They possess singularly varied beaks, some having this organ 
much thickened like those of finches, to which family some of 
them have been supposed to belong. In any case, they form a 
most peculiar group, and cannot be associated with any other 
known birds. The last species, and the only one not belonging 
to a peculiar genus, is the Hawaiian crow, belonging to the al- 
most universally distributed genus Corvus. 

On the whole, the affinities of these birds are, as might be ex- 
pected, chiefly with Australia and the Pacific Islands; but they 
exhibit in the buzzard, one of the owls, and perhaps in some of 
the Diepanididffi, slight indications of very rare or very remote 
communication with America. The amount of speciality is, how- 
ever, wonderful, far exceeding that of any other islands ; the 
only approach to it being made by New 2^aland and Madagas- 
car, which have a much more varied bird fauna and a smaller 



ISUND UFE. 



tPAaxIL 



proportionate number of peculiar genera. These fuels undoubt- 
edly indicate an iniracnsQ antiquity for this group of islands, ov 
the vicinity of some very ancient land (now submerged), from 
wliich some portion of their peculiar fauna might be derived. 

lieptlUs. — The only other vertebrate animals are two lizards. 
One of these ia a very wide-spread species, Ahltfpliarua pacilo- 
pleurus, Buid by Dr. (riinther to be found in Timor, Australia, 
the Samoa Islands, and the Sandwicli Islands. It seems hai-dly 
likely tliat such a i-ange can be due to natural causes. The 
other is said to form a peculiar genus of geckoes, but both its 
locality and aflinitios appear to bo somewhat doubtful. 

Laiul SluslU. — The only other group of animals which has 
been carefully studied, and which presents features of esjiecial in- 
terest, are the land shells. These are very numerous, about thirty 
genera and between three and four hundred species having been 
described; and it is remarkable that this single group contains 
as many species of land shells as all the other Pulynesian islands 
from tlie Felow Islands and Samoa to the Marquesas. All the 
species are peculiar, and about throe fourths of the whole belong 
to peculiar genera, fourteen of which constitute the sub-family 
Achatiuellinie, entirely contined to tliis group of islands and con- 
stituting its most distinguishing feature. Thirteen genera (com- 
prising sixty -four species) are found also in the other Polynesian 
islands, but three genera of Auriculidie (Pleootroma, Pedipes, 
and Elanneria) are not found in the Piicitie, but inhabit — the 
former genus Anstralia, China, Bourbon, and Cuba, the two lat- 
ter the West Indian Islands. Another remarkable peculiarity 
of these islands is the small number of Operculata, which are 
represented by only one genua and live species, while the other 
Pacilic islands have twenty genera and 115 species, or more 
than half the number of the Inoperculata. Tliis difference is 

LKO remarkable that it is worth stating in a comparative form : 
laoptrciilnl*. OparcnlKU. AaricnlidiK 

Snndwicli Mnndi iVi-l T, 9 

Ucal of I'ndlic island* .. SOO IIS 16 

When we remember that in the West Indian Islands the 
Operculata abound in a greater proportion than even in the 
IZZI 



Chap. XV.] THE SANDWICH ISLANDS. 299 

stone, which is plentiful in both these areas, is especially favor- 
able to them, while the purely volcanic rocks are especially un- 
favorable. The other peculiarities of the Sandwich Islands, 
however, such as the enormous preponderance of the strictly 
endemic Achatinellinse, and the presence of genera which occur 
elsewhere only beyond the Pacific area in various parts of the 
great continents, undoubtedly point to a very remote origin, at a 
time when the distribution of many of the groups of Mollusca 
was very different from that which now prevails. 

A very interesting feature of tlie Sandwich group is the ex- 
tent to which the species and even the genera are confined to 
separate islands. Thus the genera Carelia and Catinella, with 
eight species, are peculiar to the island of Kaui ; Bulimella, 
Apex, Frickella, and Blauneria to Oahu; Perdicella to Maui; 
and Eburnella to Lanai. The Rev. John T. Gulick, who has 
made a special study of the Achatinellinse, informs us that the 
average range of the species in this sub-family is five or six 
miles, while some are restricted to but one or two square miles, 
and only very few have the range of a whole island. Each val- 
ley, and often each side of a valley, and sometimes even every 
ridge and peak, possesses its peculiar species.* The island of 
Oahu, in which the capital is situated, has furnished about half 
the species already known. This is partly due to its being more 
forest-clad, but also, no doubt, in part to its being better ex- 
plored ; so that, notwithstanding the exceptional riches of the 
group, we have no reason to suppose that there are not many 
more species to be found in the less explored islands. Mr. Gulick 
tells us that the forest region that covers one of the mountain- 
ranges of Oahu is about forty miles in length, and five or six 
miles in width, yet this small territory furnishes about 175 spe- 
cies of Achatinellinae, represented by 700 or 800 varieties. The 
most important peculiar genus, not belonging to the Achatinella 
group, is Carelia, with six species and several named varieties, 
all peculiar to Kaui, the most westerly of the large islands. This 
would seem to show that the small islets sti*etching westward, 

* Journal of the LinrKran Society^ 1873, p. 406, '* On Diversity of Evolution 
ander one Set of External Conditions." Proceedings of the Zoological Society of 
London^ 1873, p. 80, " On the Classification of the Achatinellinn.*' 



800 ISLAND LIFE. [I'Adt II. 

and Bittiatcd on an extensive bank with less tlian a thotieand 
fathoms of water over it, may indicate the position of a large 
submerged island whence some portion of the Sandwich Island 
fauna was derived. 

Insects. — Unfortunately we have as yet no 6uch knowledge 
of the insects of these islands as we possess in tlic ease of the 
Azores and St. Helena, but some considerable collections have 
been sent over by Mr. T. Blackburn, now resident there, and we 
may therefore soon possess fuller and more accurate information, 
Although insects are said to be very scarce, yet all the chief 
tribes of Coleoptera appear to be represented, though as yet by 
very few species. These appear to be, for the most part, peculiar, 
but to have wide-spread affinities. The majority, as might be ex- 
pected, are allied to Polynesian, Australian, or Malayan forms; 
some few are South American (perhaps introduced), while others 
show north temperate affinities. There are several new genera, 
and one peculiar group of six species is said to form a new family 
allied to the Anthribidis. A new genus of Lucanidfe is said to 
be allied to a Chilian genus. If we consider the greater facilities 
of insects for dispersal when compared with birds or land shells, 
the characteristics of the insect fauna, so far as yet known, are 
sufficiently in harmony with the amount of speciality and isola- 
tion presented by the latter groups. 

Vetfdation of the Sandwich Islands. — The flora of these isl- 
ands is in many respects so peculiar and remarkable, and so well 
supplements the information derived from its interesting but 
scanty fauna, that a brief account of its more striking features 
will not be out of place; and wo fortunately have a pretty full 
knowledge of it, owing to the researches of the American bota- 
nist Horace Mann, and of Dr. Pickering, who accompanied the 
United States Exploring Expedition. 

Considering their extreme isolation, their uniform volcanic 
soil, and the large proportion of the chief island which consists 
of barren lava-flelds, the flora of the Sandwich Islands is ex- 
tremely rich, consisting, so far as at present known, of 554 spe- 
cies of flowering plants and 135 ferns. This is considerably 
riclier than the Azores (439 Phanerogams and 39 ferns'), which, 
though less extensive, are far better known, or than the Gain- 



Chap. XV.] THE SANDWICH ISLANDS. 801 

pagos (332 Phanerogams), which are more strictly comparable, 
being equally volcanic, while their somewhat smaller area may 
perhaps be compensated by their proximity to the American 
continent. Even New Zealand, with more than twenty times 
the area of the Sandwich group, whose soil and climate are 
much more varied, and whose botany has been thoroughly ex- 
plored, has not double the number of flowering plants (935 spe- 
cies), while in ferns it is barely equal. 

Pecxdiar Feaiures of the Flora. — This rich insular flora is 
wonderfully peculiar, for if we deduct 69 species, which are 
believed to have been introduced by man, there remain 620 spe- 
cies, of which 377, or more than three fifths, are quite peculiar 
to the islands. There are no less than 39 peculiar genera out of 
a total of 253, and these 39 genera comprise 153 species, so that 
the most isolated forms are those which most abound and thus 
give a special character to the flora. Besides these peculiar 
types, several genera of wide range are here represented by 
highly peculiar species. Such are Lobelia, the Hawaiian species 
of which are woody shrubs from six to twenty feet high, one 
even being a tree reaching a height of forty feet. Shrubby 
geraniums fifteen feet high grow as epiphytes on forest trees, as 
do some Yacciuiums and Epacrids. Violets and plantains also 
form tall shrubby plants, and there are many strange arbores- 
cent Compositse, as in other oceanic islands. 

The affinities of the flora generally are very wide. Although 
there are many Polynesian groups, yet Australian, New Zealand, 
and American forms arc equally represented. Dr. Pickering 
notes the total absence of a large number of families found in 
Southern Polynesia, such as Dilleniacese, Anonaceae, Olacacese, 
Aurantiaceae, Guttiferae, Malpighiacese, Meliaceae, Combretacefle, 
Ehizophoraccae, Melastomaceee, Passifloraceae, Cunoniaceae, Jas- 
minaceae, Acanthaceae, Myristicaceae, Casuaraceae, Scitamineae, 
and Aracae, as well as the genera Clerodendrum, Ficus, and epi- 
dcndric orchids. Australian aflinities are shown by the genera 
Exocarpus, Cyathodes, Melicope, Pittosporum, and by a phyl- 
lodinous Acacia. New 2^aland is represented by Ascarina, Co- 
prosma, Acaena, and several Cyperaceae ; while America is rep- 
resented by the genera Nama, Gunnera, Phyllostegia, Sisyrin- 



302 



ISLASD LIFE. 



[Pabt II. 



diium, and by a red-flowered Rnbus and a yellow-flowered Sanic- 
u!a allied to Oregon species. 

There is no true alpiae flora on the higher enmmits, but sev- 
ei-al of the temperate forms extend tu a great elevntiuii. Thus 
Mr. Pickering records Vaccinium, Ranmiculua, Sileiie, Gnapha- 
Huni, and Geranium as occnmng above ten lhonB.iiid feet ele- 
vation; while Viola, Drosera, Actenn, Lobelia, Edwardsia, Do- 
donsea, Lycopodium, and many CorapositEe range above six 
thousand feet. Vaccinium and Silene are veiy interesting, as 
they are peculiar to the north temperate zone, except one Sileny 
in South Africa. 

The proportionate abundance of the different families in this 
interesting flora is as follows: 



1. Compodlffi 47ii>acies. 

2. Cjiierflcea! 3D " 

8. LobeliaceiB 85 " 

i. RuluceB! 83 " 

5. Lnbiotie 27 " 

6. LcgnminiwB SO " 

7. Huweae 17 " 

8. Caryo]iliyllaceu 14 " 

9. GcsiioriiicoK. 1* " 

10. UrticaccK 13 " 



II. Piperacea 

la. CollVQlvulttfOtt! .. 

13. Miilviicca 

II. Amnrnntncon.-. 

IS. AmliaceRi 

18. Violneo* 

IT. riiionimracett,.. 

IS. MvflnreiB 

IS), GiMHleninceic 

'2t>. Th) melauen 






Four other orders — Geraniaceffi, Riiamnacete, RosacetP, and 
CncurbitaeeiE — have Ave species each ; and among the more im- 
portant oi'dera which have less than live species each are Ranun- 
cnlaceie, Eiicaceae, Prinmlacese, Polygonaccte, Orchidaceie, and 
Juncaceffi. In the above enumeration the grasses (Graminacete) 
are omitted, as they were not described at the time Mr. Mann's 
article was written, Tlie most remarkable feature here is the 
great abundance of Lobeliaccffi, a character of the flora which is 
probably unique; while the superiority of Labiatw to Legnnii- 
noBie and the scarcity of Rosacese and Orcliidaccfc are also very 
nnusual. Composites, as in most temperate floras, stand at the 
head of the list, and as these have been carefully studied by Mr. 
Bcntham, it will be interesting to note the afSnitics which they 
indicate. Omitting four genera and species wliieli are cosmo- 
politan, and have no doubt entered with civilized man, there re- 



Chap. XV.] THE SANDWICH ISLANDS. 303 

main twelve genera and forty-fonr species of Composit© in the 
islands. All the species are peculiar, as are six of the genera ; 
and in another genus, Coreopsis, the six species form a peculiar 
named section or sub-genus, Campylotheca ; while the genus 
Lipocheeta, with ten species, is only known elsewhere in the 
Galapagos, where a single species occurs. We may therefore 
consider that eight out of the twelve genera of Hawaiian Com- 
positsB are really confined to the archipelago. The relations of 
the genera are thus given by Mr. Bentham : 

No. of Species. External Relations of the Species. 

Lflgenopliora 1 Witli the Old World and Extmtropical America. 

Aster 1 American and Extratropical Old World. 

Tetramolubium G South Extratropical American. 

Vittadinia 1 South Extratropical American and Australian. 

Campylotheca (s.g.). . G With the Tropical American and very few Old World 

species of Coreopsis and Bidens. 

Bidens 1 The IVopicnl American species. 

Lipochaeta 10 American Wedelioidos and Helianthioidse. 

Argyroxiphium 2 With Madica of the Mexican region. 

Wilkesia 1 With Madieie of the Mexican region. 

Dubantin 3 Distantly with Madieas and Galinsogen of the Mexi- 
can region. 

Baillardia 11 W^ith Riiillnrdella of the Mexican region. 

Hesperomannin 1 With Stifftin and Wunderlichia of the Brasilian re- 
gion. 

The great preponderance of American relations of the Com- 
positffi, as above indicated, is very interesting and suggestive. 
It is here that we meet with some of the most isolated and re- 
markable forms, implying great antiquity ; and when we con- 
sider the enormous extent and world-wide distribution of this 
order (comprising ten thousand species), its distinctness from all 
others, the great specialization of its flowers to attract insects, 
and of its seeds for dispersal by wind and other means, we can 
hardly doubt that its origin dates back to a very remote epoch. 
We may therefore look upon the Compositae as representing the 
most ancient portion of the existing flora of the Sandwich Isl- 
ands, carrying us back to a very remote period when the facili- 
ties for communication with America were greater than they 
are now. This may be indicated by the two deep submarine 
banks in the North Pacific, between the Sandwich Islands and 



304 



ISLAND LIFE. 



tir. 



San Francisco, wliicb, from an ocean-floor nearly 3000 fatboitis 
deep, rise np to within a few hundred fathoms of the snrface, 
and eeeni to indicate the subsidence of two islands, each about 
as large as Hawaii. The plants of north tempemte affinity may- 
be nearly as old, but these may have been derived from North- 
ern Asia by way of Japan and the extensive line of elioala 
which run nortliweatwai'd from the Sandwicli Islands as shown 
on our uiap. Those which exhibit Polynesian or Australian 
affinities, consisting, for the most part, of less highly modified 
species usually of the same genera, may have had their origin at 
II later, though still somewhat remote, period, when large islands, 
indicated by the extensive shoals to the south and southwest, 
offered facilities for the transmission of plants from the tropical 
portions of the Pacific Ocean. 

Antiquity I'f the Hawaiian Fauna and Flora. — The great an- 
tiquity implied by the peculiarities of the fauna and tlors, no 
less than by the geographical conditions and surroundings, of 
this group will enable us to account for another peculiarity of 
its flora— the absence of so many families found in other Pacific 
islands. For the earliest immigrants would soon occupy much 
of the snrface, and become specially modified in accordance with 
the conditions of the locality, and these would serve ns a bar- 
rier against the intrusion of many forms which at a later period 
Bpi-ead over Polynesia. The extreme remoteness of the islands, 
and the probability that they have always been more isolated 
than those of the Central Pacific, would also necessarily result 
in an imperfect and fragmentary representation of the flom of 
sun'ounding lands. 

Vonchuliiuj Observations on tfie Fauna nud Flora ofthe&iml' 
wich Inlands. — The indicationa thus aflforded by a study of the 
flora seem to accord well with what we know of the fauna of 
the islands. Plants, having so much greater facilities for disper- 
sal than animals, and also having greater specific longevity and 
greater powers of endurance under adverse conditions, ciihibit 
in a considerable degree the influence of the primitive slate of 
the islands and their surroundings; while members of the ani- 
mal world, passing across the sea with greater difficulty, and 
subject to extermination by a variety of adverse conditions, re- 



Chap. XV.] OCEANIC ISLANDS. 305 

tain much more of the impress of a recent state of things, with, 
perhaps, here and there an indication of that ancient approacli 
to America so clearly shown in the Compositse and some other 
portions of the flora. 

General Remarlcs on Oceanic Inlands, — We have now reviewed 
the main features presented by the assemblages of organic forms 
which characterize the more important and best-known of the 
oceanic islands. They all agree in the total absence of indig- 
enous mammalia and amphibia ; while their reptiles, when they 
possess any, do not exhibit indications of extreme isolation and 
antiquity. Their birds and insects present just that amount of 
specialization and diversity from continental forms which may be 
best explained by the known means of dispei^sal acting through 
long periods ; their land shells indicate greater isolation, owing 
to their admittedly less effective means of conveyance across 
the ocean ; while their plants show most clearly the effects of 
those changes of conditions which we have reason to believe 
liave occurred during the Tertiary epoch, and preserve to us in 
highly specialized and archaic forms some record of the prime- 
val immigration by which the islands were originally clothed 
with vegetation. But in every case the series of forms of life 
in these islands is scanty and imperfect as compared with far 
less favorable continental areas, and no one of them presents 
tuicli an assemblage of animals or plants as we always find in an 
island which we know has once formed part of a continent. 

It is still more important to note that none of these oceanic 
archipelagoes present us with a single type which we may sup- 
pose to have been preserved from Mesozoic times ; and this fa'ct, 
taken in connection with the volcanic or coralline origin of all 
of them, powerfully enforces the conclusion at which we have 
arrived in the earlier portion of this volume, that during the 
whole period of geologic time, as indicated by the fossiliferous 
rocks, our continents and oceans have, speaking broadly, been 
permanent features of our earth's surface. For had it been oth- 
erwise — had sea and land changed place repeatedly, as was once 
supposed ; had our deepest oceans been the seat of great conti- 
nents, while the site of our present continents was occupied by 
an oceanic abyss — is it possible to imagine that no fragments 

20 



306 ISLAND LIFE. [Pabt II. 

of Bucli continents would remain in the present oceans, bringing 
down to us some of their ancient forms of life preserved with 
but little change ? The correlative facts that the islands of our 
great oceans are all volcanic (or coralline built, probably, upon 
degraded and submerged volcanic islands), and that their pro- 
ductions are all more or less clearly related to the existing in- 
habitants of the nearest continents, are hardly consistent with 
any other theory than the permanence of oceanic and continental 
areas. 

We may here refer to the one apparent exception, which, 
however, lends additional force to the argument. New Zealand 
is sometimes classed as an oceanic island, but it is not so really ; 
and we shall discuss its peculiarities and probable origin further 
on. 



Chap. XVI.] TUE BRITISH ISLES. 307 



CHAPTER XVI. 

CONTINENTAL ISLANDS OF RECENT ORIGIN: GREAT BRITAIN. 

Characteristic Features of Recent Continental Islands. — Recent Physical Changes 
of tlie British Isles. — Proofs of Former Elevation. — Submerged Forests. — Buried 
River Channels. — Time of Last Union with the Continent. — Why Britain is Poor 
in Species. — Peculiar British Birds. — Fresh-water Fishes. — Cause of Great Spe- 
ciality in Fishes. — Peculiar Biitish Insects. — Lepidoptera Confined to the British 
Isles. — Peculiarities of the Isle of Man Lepidoptera. — Coleoptera Confhied to 
the British Isles. — Trichoptera Peculiar to the British Isles. — Land and Fresh- 
water Shells. — Peculiarities of the British Flora. — Peculiarities of the Irish Flora. 
— Peculiar British Mosses and Hepaticie. — Concluding Remarks on the Peculiari- 
ties of the British Fauna and Flora. 

We now proceed to examine those islands which are the very 
reverse of the " oceanic " class, being fragments of continents or 
of larger islands from which they have been separated by sub- 
sidence of the intervening land at a period which, geologically, 
must be considered recent. Such islands are always still con- 
nected with their parent land by a shallow sea, usually, indeed, 
not exceeding a hundred fathoms deep; they always possess 
mammalia and reptiles either wholly or in large proportion 
identical with those of the mainland ; while their entire flora 
and fauna are characterized either by the total absence or com- 
parative scarcity of those endemic or peculiar species and genera 
which are so striking a feature of all oceanic islands. Such isl- 
ands wull, of course, differ from each other in size, in antiquity, 
and in the richness of their respected faunas, as well as in their 
distance from the parent land and the facilities for intercom- 
munication with it; and these divereities of conditions will man- 
ifest themselves in the greater or less amount of speciality of 
their animal productions. 

This speciality, when it exists, may have been brought about 
in two ways. A species or even a genus may on a continent 
have a very limited area of distribution, and this area may be 



ISLAND LIFE. 



[Part 11. 



wholly, or iilinoat wholly, contained in t!ie sepamteJ portion op 
island, to wliidi it will hencefortJi be peculiar. Even when the 
area occupied by a species is pretty equally divided at tho time 
of eeparatioii between the island and the continent, it may hop- 
pen that it will become extinct on the latter, while it may eur- 
vive on the former, because the limited number of individuals 
after division may be unable to maintain themselves against the 
severer competition or more contrasted climate of the coutinent, 
while they may flourish under the more favorable insular condi- 
tions. On the other hand, when a species continues to exist in 
both areas, it may on the island be subjected to some modifica- 
tions by the altered conditions, and may thus come to present 
chamcters which differentiate it from its continental allies and 
constitute it a new species. We shall in the couree of our sur- 
vey meet with eases illustrative of both these processes. 

The best examples of recent continental islands are Great 
Britain and Ireland, Japan, Formosa, and the larger Malay isl- 
ands, especially Borneo, Java, and Celebes ; and as each of these 
presents special features of interest, wo will give a short outline 
of their zoology and past liistory in relation to that of the con- 
tinents from wliieh they have recently been separated, com- 
mencing with our own islands, to which the present chapter will 
bo devoted. 

J^ecent Phym-al Changes in tJus Bntl«h Idf-8. — Great Britain 
is perhaps the most typical example of a large and recent con- 
tinental island now to be found upon the globe. It is joined to 
the continent by a shallow bank which extends from Dtninark 
to the Bay of Biscay, tlie lOO-fathom line from these c\tremc 
points receding from the coasts so as to include the whole of 
the British Isles and aboot fifty miles beyond them to the west- 
wai-d. (See map.) Beyond this line the sea deepens rapidly to 
the 600 and 1000 fathom lines, the distance between 100 and 
1000 fathoms being fram twenty to fifty miles, except where 
there is a grout outward curve to include the Porcupine Bank, 
170 miles west of Galwny, and to the northwest of Caithness, 
where a narrow ridge less than 500 fathoms bolow the surface 
joins the extensive bank under 300 fathoms, on which are situ- 
ated the Faroe Islands and Iceland, and which stretches across 



CHif.STL] THE BRITISH 18LE8. SOft 

to Greenlnnd. In the Nortli Chauuel between Ii-elaiid and Scot- 
liind, and in t!ic Minch between tlie onter Ilebndea and Skye, 
are a series of ludl.uvs in tlie Sfu-bottmn from lOU tu IHO f.itliotns 




'i'li« liglit tint indicniGs ■ depdi of Ust (lian 100 fiithoms. 

The fiKurci thaw liie depth in ritthnm*. 

Tlie iian'uiv cliatinel beliveen Noin'n/ nnJ Denmnvli is 2180 fvcl Jvcp. 

deep. Tliese correspond exactly to the points between tlie op- 
posing htgtdande where the greatest accnmulations of ice wonid 
necessarily occur during the glacial cpoclt. and they may well 



310 



ISLAND LIFE. 



[PARTlr. 



be termed Eiibmariiie lakes, of exactly tlie same nature as those 
wliicli occur in similar positiung on land. 

Proof 8 nf Former EUvation—Sulmerifed Forests. — Wliat ren- 
ders Britain particultirly ingtriictivo as an example of a recent 
continentnl island is the amount of direct evidence that exists, of 
several distinct kinds, showing that tiic land has been sufficiently 
elevated (ov the sea depressed) to unite it witL the continent — ■ 
and tliis at a very recent period. The first class of evidence ia 
the existence, all round onr coasts, of the remains of submarine 
forests often extending far below the present low-water mark. 
Such arc the submerged forests near Tor<i»ay in Devonshire, 
and near Falmouth in Cornwall, both containing stumps of trees 
in tlieir natural position rooted in the soil, with deposits of peat, 
brnncJies, and nnts, and often with remains of insects and other 
land animalB. These occur in very different conditions and sit- 
uations, and some have been explained by changes in the height 
of the tide, or by pebble banks shutting out tlie tidal waters 
from estuaries; but there are nnmerous examples to which such 
hypotheses cannot apply, and which can only be explained by an 
actual subsidence of tlie land (or rise of the sea-level) since the 
trees grew. 

We eannot give a better idea of those forests than by quoting 
the following account by Mr. I'engclly of a visit to one which 
liad been exposed by a violent storm on the coast of Devonshire, 
at Blackpool, near Dartmouth ; 

•'We were so fortunate as to reach the beach nt spring-tide 
low water, and to find, admirably exposed, by far the finest ex- 
ample of a submerged forest which I have ever seen. It occu- 
pied a rectangular area, extending from the small river or stream 
at the western end of tlie inlet about one furlong eastward, 
and from the low-water lino thirty yards np the strand. The 
lower or seawaivl portion of the forest area, ocenpying about 
two thirds of Its entire breadth, eonsisted of a brownish drab- 
colored clay, which was crowded with vegetable dubris, such ee 
small twigs, leaves, and nnts. Tliero were also numerous pros- 
trate trunks and branches of trees, lying partly eml)edded in the 
clay, williout anything like a prevalent direction. The trunks 
varied from six inclics to uiiivurde of two feet in iliameter. 



Chap. XVI.] TUB BRITISH ISLES. 811 

Much of the wood was found to have a reddish or bright-phik 
hue when fresh surfaces were exposed. Some of it, as well as 
many of the twigs, had almost become a sort of ligneous pulp ; 
while other examples were firm, and gave a sharp crackling 
sound on being broken. Several large stumps projected above 
the clay in a vertical direction, and sent roots and rootlets into 
the soil in all directions and to considerable distances. It was 
obvious that the movement by which the submergence was ef- 
fected had been so uniform as not to destroy the approximate 
horizontality of the old forest ground. One fine example was 
noted of a large prostrate trunk having its roots still attached, 
some of them sticking up above the clay, while others were buried 
in it. Hazel-nuts were extremely abundant — some entire, others 
broken, and some obviously gnawed. ... It has been stated that 
the forest area reached the spring-tide low-water line ; hence as 
the greatest tidal range on this coast amounts to eighteen feet, 
we are warranted in inferring that the subsidence amounted to 
eighteen feet as a minimum, even if we suppose that some of 
the trees grew in a soil the surface of which was not above the 
level of high water. There is satisfactory evidence that in Tor- 
bay it was not less than forty feet, and that in Falmouth harbor 
it amounted to at least sixty-seven feet."* 

On the coast of the Bristol Channel similar deposits occur, as 
well as along much of the coast of Wales and in Holyhead har- 
bor. It is believed by geologists that the whole Bristol Channel 
was, at a comparatively recent period, an extensive plain, through 
which flowed the river Severn ; for, in addition to the evidence 
of submerged forests, there are on the coast of Glamorganshire 
numerous caves and fissures in the face of high sea-cliffs, in one 
of which no less than a thousand antlere of the reindeer were 
found, the remains of animals which had been devoured there 
by bears and hyenas — facts wliich can only be explained by the 
existence of some extent of dry land stretching seaward from 
the present cliffs, but since submerged and washed away. This 
plain may liave continued down to very recent times, since the 
whole of the Bristol Channel to beyond Lundy Island is under 

• Geological Maf/azine, 1870, p. 165. 



313 



ISLAND LIFE. 



[l'*m 11. 



twetitj'-fivc fiitlioms deep. In tlio Eiist of Enghnd wc liavc a 
similar forest-bed at Cromer in Norfolk ; and in the North of 
Holland an old land sarface has been fonnd fifty-six feet helow 
liigli-walcr mark. 

Bui'ifd liiver Channel. — Still more remarkable are the buried 
river channels whieh Im%'e been ti'sced oti many parts of our 
coasts. In order to-facilitato tlie Btiidy of the glacial deposits 
of Scotland, Dr. James Croll obtained the details of about two 
hundred and fifty bores put down in all parts of the mining dis- 
tricts of Scotland for the purpose of discovering minerals.' These 
revealed the interesting fact that there arc ancient valleys and 
river channels at depths of from lOO to 200 feet below the pres- 
ent sea-level. TJiese old rivers sometimes run in quite different 
directions from the present lines of drainage, connecting what 
are now distinct valleys ; and they are so completely filled np 
and hidden by boulder clay, drift, and sands that there is no in- 
dication of their presence on the surface, which often consists of 
mounds or low bills more than 100 feet high. One of these old 
valleys connects the Clyde near Dumbarton with the Forth at 
. Grangemouth, and appears to have contained two streams flow- 
ing in opposite directions from a watcr-sbcd abont midway at 
Kilsith. At Grangemouth the old channel is 260 feet below 
the sea-level. The water-shed at Kilsith is now 160 feet above 
the sea — the old valley-bottom being 120 feet deep, or 40 feet 
above the sea. In some ])Iace6 the old valley was a ravine witli 
precipitous rocky walls, which have been found in mining cxcsxQ 
vations, Br. Geikie, who has himself discovered many t 
buried valleys, is of opinion that "they nnqucstionabjy belongf 
to the period of the boulder clay." 

We have here a clear proof that when these rivers were form- 
ed the land must have stood in relation to the sea at ha»t 260 
feet higlier than it does now, and probably much more ; and this 
is sufficient to join England to the continent. Supporting this 
evidence, we have fresh-water or littoral sheila found at great 
depths off our coasts. Mr. (iodwin Austen recoi-da the dredging- 
up of a fi-esh-water shell {Unio pietorutn) oS the mouth of the 

' Trantarlioni n/rA(. RHnlmrs/, C^rgiml Sxritls. Vol. I, 




Chap. XVI.] THE BRITISH ISLES. 813 

English Channel between the 50-fathom and lOO-fathom lines, 
while in the same locality gravel banks with littoral shells now lie 
under sixty or seventy fathoms water/ More recently Mr. G wyn 
Jeffreys has recorded the discovery of eight species of fossil arc- 
tic shells off the Shetland Isles in about ninety fathoms water, 
all being characteristic shallow-water species, so that their asso- 
ciation at this great depth is a distinct indication of considerable 
subsidence.' 

Time of Last Union with the Continent. — The period when 
this last union with the continent took place was comparatively 
recent, as shown by the identity of the shells with living species, 
and the fact that the buried river channels are all covered with 
clays and gravels of the glacial period, of such a character as to 
indicate that most of them were deposited above the sea-level. 
From these and various other indications geologists are all agreed 
that the last continental period, as it is called, was subsequent to 
tlic greatest development of the ice, but probably before the 
cold epoch had wholly passed away. But if so recent, we should 
naturally expect our land still to show an almost perfect com- 
munity with the adjacent parts of the continent in its natural 
productions ; and such is found to be the case. All the higher 
and more perfectly organized animals are, with but few excep- 
tions, identical with those of France and Germany ; while the 
few species still considered to be peculiar may be accounted for 
either by an original local distribution, by preservation here ow- 
ing to favorable insular conditions, or by slight modifications 
having been caused by these conditions resulting in a local race, 
sub-species, or species. 

Why Bintain is Poor in Species. — The former union of our 
islands with the continent is not, however, the only recent change 
they have undergone. There is equally good evidence that a 
considerable portion, if not the entire area, had been submerged 
to a depth of nearly 2000 feet (see Chap. IX., p. 166), at which 
time only what are now the highest mountains would remain as 
groups of rocky islets. This submersion must have destroyed 



» Quarter!^ .Journal of Geological Society^ 1 8oO, p. 9G. 
• ** British Association Report," Dundee, 18C7, p. 431. 



8U 



ISLASD LIFE. 



[PiBTlL 



the gi-eater part of the life of our country; and ns it certainly 
occurred during the latter part of the glacial epoch, the siibse- 
queut elevation and union with the continent cannot have been 
of very long duration, and this fact must have had an important 
bearing on the character of the existing fauna and flora of Brit- 
ain. We know that just before and during the glacial period 
we posseesed a fauna ahnost or quite identical with that of ad- 
jacent parts of the continent, and e()iially rich in species. The 
submergence destroyed this fauna ; and the peniianent change 
of climato on the passing-away of the glacial conditions appears 
to have led to the extinction or migration of many species in 
the adjacent continental areas, where they were succeeded by the 
assemblage of animals now occupying Central Europe. Wlicn 
England became continental, these entered our country; hut 
sufficient time does not seem to have elapsed for the migration to 
have been completed before subsidence again occurred, cutting 
off the further influx of purely terrestrial animals, and leaving 
us withont the number of species which our favorable climato 
and varied surface entitle na to. 

To this cause wo must impute our comparative poverty in 
mammalia and reptiles — more marked in the latter than thefoi"- 
mer, owing to their lower vital activity and smaller powers of 
dispersal. Germany, for example, possesses nearly ninety species 
of land mammalia, and even Scandiuavia about sixty, while Brit- 
ain has only forty, and Ireland only twenty-two. The depth of 
tho Irish Sea being somewhat greater than that of the German 
Ocean, the connecting land would thus probably be of small ex- 
tent and of lees duration, thus offering an additional barrier to 
migration, whence has arisen tho comparative zoological poverty 
of Ireland. This poverty attains its maximum in the reptiles, aa 
sliown by the following fignres: 

Bulgiiim has 22 epecics of reptiles nnd amjihibi.i. 



Where the power of flight existed, and thns the period of n 
gratiou was prolonged, tho difference is leas marked; so that 
Ireland has seven bats to twelve in Britain, and about 110 as 

a":iinst 130 land birds. 



OiiAP.XVI.J THE BRITISH ISLES. 315 



Plants, which have considerable facilities for passing over the 
sea, are somewhat intermediate in proportionate numbers, there 
being about 970 flowering plants and ferns in Ireland to 1425 
in Great Britain — or almost exactly two thirds, a proportion 
intermediate between that presented by the birds and the mam- 
malia. 

Peculiar Brituh Birds, — Among our native mammalia, rep- 
tiles, and amphibia, it is the opinion of the best authorities that 
we possess neither a distinct species nor distinguishable variety. 
In birds, however, the case is diflEerent, since some of our spe- 
cies, in particular our coal-tit {Parus ater) and long-tailed tit 
{Parus caudatm) present well-marked diflferences of color as 
compared with continental specimens; and in Mr. Dresser's 
work on the " Birds of Europe " they are considered to be dis- 
tinct species; while Professor Newton, in his new edition of 
Yarrell's " British Birds," does not consider the difference to be 
suflieiently great or sufficiently constant to warrant this, and 
tlierefore classes them as insular races of the continental species. 
We have, however, one undoubted case of a bird peculiar to the 
British Isles in the red grouse {Lagopus Scoticms)^ which abounds 
in Scotland, Ireland, the North of England, and Wales, and is 
very distinct from any continental species, though closely allied 
to the willow-grouse of Scandinavia. This latter species resem- 
bles it considerably in its summer plumage, but becomes pure 
white in winter; whereas our species retains its dark plumage 
throughout the year, becoming even darker in winter than in 
summer. We have here, therefore, a most interesting example 
of an insular form in our own country ; but it is difficult to de- 
termine how it originated- On the one hand, it may be an old 
continental species which during the glacial epoch found a ref- 
uge here when driven from its native haunts by the advancing 
ice ; or, on the other hand, it may be a descendant of the North- 
ern willow-grouse, which has lost its power of turning white in 
winter owing to its long residence in the lowlands of an isl- 
and where there is little permanent snow, and where assimila- 
tion in color to the heather among which it lurks is at all 
times its best protection. In either case it is equally interest- 
ing, as the one large and handsome bird which is peculiar to 



316 



ISLAND LIFE. 



[Haf 



our islands, iiotwitiistanduig their recent sepnmtion fi'oiii tlie 
continent. 

The following is a list of birds now held to be peculiar to the 
British Isles : 



t. Parut Si 



oflhe 






M. .Closely allieJ to P. 

2. " roiea Allied W P. raiirfadaof iliecouiinem. 

3. Lajopnu SH)tiBtu...Ai\\vd Ut L. a^Wof Sonnilmnvm, but VGI7 dint i net. 

Freeh-waier Fishes. — Altlioiigli the productions of fresli wa- 
ters have generally, as Mr. Darwin has shown, a wide range, 
fishes appear to form an exception, many of them being ex- 
tremely liinited in distribution. Some are confined to particu- 
lar river valleys or even to single rivers, others inhabit the lakes 
of a limited district only, while Bomo are eoniiued to single lakes 
— often of small area — and these latter offer examples of the 
most restricted distribntion of any organisms whatever. Cases 
of this kind are found in our own islands, and deserve our es- 
jiQcial attention. It has long been known that some of our lakes 
possessed peculiar siiecies of trout and char ; but liow far these 
were unknown on the continent, and how many of these in dif- 
ferent parts of our islands were really distinct, had not been 
ascertained till Dr. Oiinthcr, so well known for his extensive 
knowledge of the s})eeios of fishes, obtained numerous speci- 
mens fro[n every part of the onntry, and by comparison with 
all known continental species determined their speciHc differ- 
ences. The striking and une.\pected result has thus been at- 
tained that no less than fifteen well-marked 6|5ecies of frosh-wa- 
tcr fiahcs are altogetlier peculiar to the British Islands. The fol- 
lowing is the list, with their English names and localities : ' 



FiiKsn-WATBB FisuEi TKCtHAn t 



E Bni 






Ijiirii Nnme. Ensllab N»m<'. laeaWtj. 

1. Salmo Arr7i^%ieMa..,Shorl-hM(la(l anlmon... .Firth of Fortli, Tivcci], Onte. 

8. " Gal/iunah. . .Gnlwiiy Ma-troiit Gnlwny, West of Irolun J. 

8. " OrrailfHtit. . .hovb Swniiis trout Lnkes of Orkney. 



I Tlio li 



r nnmea niu fonii&licJ to me liy ])r. Giiniher, nnd 1 linve ndJn] the 
llic piipcn cDninining llie uigliml JeKripiions, and fiam Dr. Ilaiigli- 



5. 




C. 




7. 




8. 




9. 


• 


10. 




11. 





Chap. XVI.] THE BRITISH ISLES. 317 

Lntin Name. English Name. Locality. 

4. Salmoferox Great lake-troat Larger lakes of Scotland, the 

North of England, nnd Wales. 
* ' stomachicus, . . Gillaroo trout Lakes of Ireland. 

ni^rt/)«nnij.... Black-finned trout. Mountain lochs of Wales and 

Scotlond. 

Levenensis, . . .Loch Leven trout Loch Leven, Loch Lomond, Win- 
dermere. 

Peinsii Welsh char Llanberris lakes, North Wales. 

ir<V/i/<7A6tt.... Windermere char Lake Windermere, and others in 

North of England, and Lake 
Bruiach in Scotland. 

Killinensis,. . .Lough Killin char Killin Lake, in Mayo, Ireland. 

Coin Cole's char Lough Eske and Lough Dan, Ire- 
land. 

12. *' (Srayi Gray 'a char Lough Melvin, Leitrim, Northwest 

of Ireland. 

13. Cortgonua clupeoides, The gwyniad, or scheIl3'..Loch Lomond, Ulleswater, Hawes- 

water, and Bala Lake. 

14. *' vandesius. . The vendace Lochmaben, Dumfriesshire. 

15. ** poilan The pollan Lough Neagh and Lough Erne, 

North of Ireland. 

These fifteen peculiar fishes differ from each other and from 
all British and continental species, not in color only, but in such 
important structural characters as the form and size of the fins, 
the number of the fin-rays, and the form or proportions of the 
head, body, or tail. They are, in fact, as Dr. Giinther assures me, 
just as good and distinct species as any other recognized species 
of fish. It may, indeed, be objected that, until all the small lakes 
of Scandinavia are explored and their fishes compared with 
ours, we cannot be sure that we have any peculiar species. But 
this objection has very little weight if we consider how our own 
species vary from lake to lake and from island to island, so that 
the Orkney species is not found in Scotland, and not one of the 
peculiar British species extends to Ireland, which has no less 
than six species altogether peculiar to it. If the species of our 
own two islands are thus distinct, what reason have we for be- 
lieving that they will be otherwise than distinct from those of 
Scandinavia? At all events, with the amount of evidence we 
already possess of the very restricted ranges of many of our spe- 
cies, we must certainly hold them to be peculiar till they have 
been proved to be otherwise. 



318 



ISLAND LIFE. 



[Pa. 



Tlio great spedulity of tlie Irish fislics is vtjrj' iiiterfstiiig, be- 
cause it is just wlmt we ehoiild expect on the tlieory of evola- 
tion. In Ireland the two main causes of epccitic change — isol:t- 
tion and altered c-onditioiis — are each more powerful than in 
Britain, Whatever difficulty continental fishes may have in pass- 
ing over to Britain, that difficulty will certainly be increased by 
the second eea passage to Ireland; and the latter country has 
been longer isolated, for the Irish Sea with its northern and 
southern channels is considerably deeper than the German Ocean 
and the eastern half of the Eugllsli Channel ; so that, when the 
last subsidence occurred, Ireland would have been an island for 
some length of time wiien England and Scotland still formed 
part of the continent. Again, whatever differences have been 
produced by the exceptional climate of onr islands will have 
been greater in Ireland, where insular conditions are at a maxi- 
mum, the abundance of moisture and the equability of tern- 
peratui-e being far more pronounced than in any other part of 
Europe. 

Among the remarkable instances of limited distribution af- 
forded by these fishes, we have the Loch Stennis trout confined 
to the little group of lakes in the mainland of Orkney, occupy- 
ing altogether an area of about ten miles by three; the Welsh 
char confined to tlie Llanborris lakes, about three mites in 
length; Gray's char confined to Lough Mel vin, about seven miles 
long; while the Lough Killin char, known only from a small 
mountain lake in Ireland, and the vendace, from the equally 
small lakes at Lochmabcn in Scotland, arc two examples of re- 
stricted distribution which can hardly be surpassed. 

Cause of Great !:<pectnU-tij in Flith^ii. — Tlie reason why fishes 
alone should e.\hibit such remarkable local modifications in lakes 
and islands is sufficiently obvious. It is dne to the extreme 
rarity of their transmission from one lake to another. Just as 
we found to be the case in oceanic islands, where the means 
of transmission were iimple hardly any modification of species 
occurred ; while, where these means were deficient, and individ- 
nala once transported remained isolated during a long sneccseion 
of ages, their forms and characters became so much changed as 
to bring about what wo term distinct species or even distinct 



Chap. XVI.] TUE BRITISH ISLES. 319 

genera — so these lake fishes have become modified because the 
means by which they are enabled to migrate so rarely occur. It 
is quite in accordance with this view that some of the smaller 
lakes contain no fishes, because none have ever been conveyed 
to them. Others contain several ; and some fishes which have 
peculiarities of constitution or habits which render their trans- 
mission somewhat less difficult occur in several lakes over a wide 
area of country, though none appear to be common to the Brit- 
ish and Irish lakes. 

The manner in which fishes are enabled to migrate from lake 
to lake is unknown, but many suggestions have been made. It 
is a fact that whirlwinds and waterspouts sometimes carry living 
fish in considerable numbers and drop them on the land. Here 
is one mode which might certainly have acted now and then in 
the couree of thousands of years, and the eggs of fishes may have 
been carried with even greater ease. Again, we may well sup- 
pose that some of these fish have once inhabited the streams that 
enter or flow out of the lakes, as well as the lakes themselves ; 
and this opens a wide field for conjecture as to modes of migra-. 
tion, because we know that rivers have sometimes changed their 
courses to such an extent as to form a union with distinct river 
basins. This has been effected either by floods connecting low 
water-sheds, by elevations of the land changing lines of drain- 
age, or by ice blocking up valleys and compelling the streams to 
flow over water-sheds to find an outlet. This is known to have 
occurred during the glacial epoch, and is especially manifest in 
the case of the Parallel Koads of Glenroy, and it probably af- 
fords the true solution of many of the cases in which existing 
species of fish inhabit distinct river basins whether in streams or 
lakes. If a fish thus wandered out of one river basin into an- 
other, it might then retire up the streams to some of the lakes, 
where alone it might find conditions favorable to it. By a com- 
bination of the modes of migration here indicated, it is not diffi- 
cult to undei'stand how so many species are now common to the 
lakes of Wales, Cumberland, and Scotland, while others less able 
to adapt themselves to different conditions have survived only 
in one or two lakes in a single district; or these last may have 
been originally identical with other forms, but have become 



ISLAND LIKE. 



riM 



nioJified by tlie parlieuliir conditions of tlic lukc in which they 
btivti found theuiBelvGB isolated. 

Peculiar lint'ish /it^-cts. — We now come to tiie class of in- 
sects, and here we hiive much more difficulty in deteriiiiiiing 
what are the actual facte, because uew species are still bein^r 
yearly discovered, and considernbie portions of Europe are but 
imperfectly explored. It often happens that an insect is discov- 
ered in onr islands, and for some years Britain is its only record- 
ed locality; btit at length it is found on some part of the con- 
tinent, and not unfrequently has been all the time known there, 
but disguised by another name, or by being classed as a variety 
of some other species. This has occurred so often that our best 
entomologists have come to take it for granted that aU our sup- 
posed peculiar British species are really natives of the continent, 
and will one day be found there; and, owing to tiiis feeling, little 
trouble has been taken to bring together the names of such as 
from time to time remain known from this country oidy. The 
view of the probable identity of our entire insect-fauna with that 
of the continent is held by such well-known authorities a& Mr. 
E. C Byo and Dr. D. Sharp for the beetles, and by Mr. li. T. 
Stainton fur butterflies and mollis; but as we have already seen 
that among two orders of vertebrates — birds and fishes — tbere 
are nudoubtcdly peculiar British species, it seems to nic that 
all tlie probabilities are in faror of there being a mnch larger 
number of peculiar species of insects. In every other island 
■where some of the vertebrates are peculiar — as in the Azores, 
the Canaries, the Andaman Islands, and Ceylon — the insects 
show an equal, if not a higher, proportion of speciality, and tliere 
seems no reason whatever why tlio saino law should not apply 
to us. Our climate is undoubtedly very distinct fi-om that of 
any part of the continent, and in Scotland, Ireland, and Wales 
■we possess extensive tracts of wild inoiintainous country where 
a moist uniform climato. an alpine or northern vegetation, and a 
considerable amount of isoiution offer all the conditions requi- 
site for the preservation of some species which may have bo- 
come extinct elsewhere, and for the slight niodilication of others 
since our last separation from the continent. I think, therefore, 
that it will be very interesting to take stock, as it were, of onr 



Chap. XVI.] THE BRITISH ISLES. 321 

recorded peculiarities in the insect world, for it is only by so 
doing that we can hope to arrive at any correct solution of the 
question on wliich there is at present so much difference of opin- 
ion. For tlie list of Coleoptera with the accompanying notes I 
am indebted to Mr. E. C. Kye ; and Dr. Sharp has also given me 
valuable information as to the recent occurrence of some of the 
supposed peculiar species on the continent. For the Lepidop- 
tera I first noted all the species and varieties marked as British 
only in Staudinger's " Catalogue of European Lepidoptera." 
This list was carefully corrected by Mr. Stainton, who weeded 
out all the species known by him to have been since discovered, 
and funiished me with valuable information on the distribution 
and habits of the species. This information often has a direct 
bearing on the probability of the insect being peculiar to Britain, 
and in some cases may be said to explain why it should be so. 
For example, the larvae of some of our peculiar species of Tine- 
ina feed during the winter, which they are enabled to do owing 
to our mild and insular climate, but which the severer conti- 
nental winters render impossible. A curious example of the 
effect this habit may have on distribution is afforded by one of 
our commonest British species, Elachista rufocinerea^ the larva 
of which mines in the leaves oi Holcus mollis and other grasses 
from December to March. This species, though common every- 
where with us, extending to Scotland and Ireland, is quite un- 
known in similar latitudes on the continent, but appears again 
in Italy, the South of France, and Dalmatia, where the mild 
winters enable it to live in its accustomed manner. 

Such cases as this afford an excellent illustration of those 
changes of distribution, dependent probably on recent changes 
of climate, which may have led to the restriction of certain 
species to our islands. For should any change of climate lead 
to the extinction of the species in South Europe, where it is far 
less abundant than with us, we should have a common and 
wide-spread species entirely restricted to our islands. Other 
species feed in the larva state on our common gorse, a plant 
found only in limited portions of Western and Southern Eu- 
rope; and the presence of this plant in a mild and insular cli- 
mate such as ours may well be supposed to have led to the pres- 

21 



323 ISLAND LIFE. [Pim II. 

ervation of some of tlie miiucroiis species wliicli iiru or Lave 
Ijcen dependent on it. 

Mr. MeLaclilan Lab kindly fiirnislted me with Eonic valnabic 
information on certain species of Triclioptera, or caddis-fllee, 
which seem to be pecnliar to onr islands; and this eoinpletea 
the iist of orders which have been studied with snllicient care 
to afford materials for such a comparison. We will now give 
the list of peculiar British insects, beginning with tlie Lepidop- 
tera, and adding siicli notes as Litvc been kindly supplied by the 
gentlemen already referred to. 

Lisr OF TUB Spkciks on Vahibties or Lefidopteba which, so faii as at rnes- 

UNt KMOWX, *Utl CuXnSED TO TUB BRITISH I»I.ANPS. 

(.Tie Fiyura SAow Ike Data when the SpfcUi leere Pint DttcriM.) 

1. Poli/ommatia ditjitir. "Tlie Inrger copper." This fine inacct, once common in 

■lie funo, but nov extinct oninB to extensire draiimgo, is genorallj' adinideJ 
lo Lb pecalinr lo oar iilund, r1 iiU events as a, vnnelj or local foim. Its can- 
lineiiut ally ilifiers consttmily in beinj; sTiialler nnd in Iiaving smxllcr ipoti; 
lilt llic difference, tliaiish constant, is eo aliglit that it is now ciaastid ns u va- 
liety under tlie nnmo of niiVim. Our insect may itierefore be iinied to be a 
wcll-tnarkcd local farm of n coniincninl species. 

2. Lycicna nsUarclie, var, Artaierxu. Tliis very dislincc Torm is conRiicd In Scot- 

land and ilie North of England. The species of nhich it ii considered n vn- 
Tia.y (more eenernllf known to English entamolosiils as P. a^islh) is found 
in the Bouihcrn liatf o( Englnnd, and almost cven'ivlteie on tlic continent. 

BoMntcKS. 
a. Lilhoaa urieta. Norlli orii;ngliind(18Cl). 

4. Ile|iialas liamull. rar. Beihlaailiia, .Shellnnd IsUnils (ISGii). A remni'kibl« 

r>irm, in whicli the male is usiinliy yellow and bulT instead of pnro while, as in 
the common funn.bul exceedingly variable In tint Bnd maikrugs. 
C, £pieknBiileri/i rctietUa. SheemeiiB, Grnvescnd, nnd oilier localities along the 
Thnrae* {1647}. 

5. E. pnlla, rar. MiAVf/ii. Nenrl-ondon (1830?). Itnre; the iipecies in Central and 

tjuiitliern Europe. (Doubtfully peculiar, in Mr. Sininton's opinion.) 

NlXTD*. 

T. AeroHiii-ln msririr. Scoilnnd only (I8n2). A dixlinL-t RpeciL-;. 

8. Affraiii mlmtta. Canitiriilgcshire nnd llunling<lun8lilre funs, peilinps extinct 

(18»fi.) The car. Mbnmlea U found in Finland and Lironin. 
!l. A. AtiuiorHiii. Soutli and West (I8ii5). Distinct and not uncommon. 
10. lHaMthfria liarrelH. Ireland (1864). Periinpt a form of the coniinentnl D. 

lutea'jo, Mr. McLacliInn thinks. 



Chap. XVI.] THE BRITISH ISLES. 323 

11. Aporophyla aiistralis, var. Pascuea. South of England (1830?). This is a vr- 

riety of a species othei'wise confined to the StnUh of Europe, and is thus espe- 
cially interesting. 

Geometry. 

12. Boarmia gcmmaria, var. perfamaria. Near London (18CC). A large dark va- 

riety of a common species, distinctly marked ; perhaps a good species, ns the 
1ar\'a feeds on ivy, while the larva of B. gemmaria is said to refuse this plant, 
and to die if it has nothing else to eat ; but Mr. McLachlan thinks this wants 
confirmation. 

13. Cidaria albulata, var. t/riseata. East of England (1835). A variety of a spe- 

cies otherwise confined to Central and Southern Europe. 

14. EupUhecia constrictata. Widely spread, but locol (1857). Lan'a on thyme. 

Pyralidina. 

15. Aglossa pinguinalis, var, Streatjieldi. Mendip Hills; unique (1830 ?). A re- 

markable and distinct variety of the common ** tabby.'' 
10. Asopia pictalis. Unique (1830?). Perhaps an imported species. 

17. Scoparia atpina, Scotland (1859). 

TOBTRICIXA. 

18. Teras Shepherdana. Fens of Cambridgeshire (1852). 

19. Cochjflis dUucidana. South of England (1829). Scarce; larva in stems of the 

wild parsnip. 

20. Aphelia nigrovittana, Scotland (1852). A local foqpo of the generally distrib- 

uted A. lanceolana. 
2\. EudemisfuUgatM. Southeast of England (1828). Hare; on fleabane. 
w2. Grapholitha navana. Generally distributed (1845). Doubtfully distinct from 

continental species, in Mr. Stainton's opinion. 

23. G. parvulana. Isle of Wight (1858?). Rare; a distinct species. 

24. G. Weirana. South of England (1850). A distinct species. 

TiN'EINA. 

25. Tinea cochylidella, Sanderstead, near Croydon (1854). Unique. 

2G. 7\ pallescentella. Near Liverpool (1854). Abundant; probably imported in 
wool, Mr. Stainton thinks. 

27. T. flavescentella. Near London (1829). Scarce; perhaps imported. 

28. Acrolepia hettdeteUa. Yorkshire and county of Durham (1840). liare. 

29. Argyresthia semifusca. North and West of England (1829). Scarce ; a distinct 

species. 
:\0. Geiechia divisella. A fen insect (1854). Rare. 

3 1 . (i. ceUrella. West of Enghind (1854). 

32. Bryophila poUtella. Moors of North of England (1854). 

33. Lita fraterneUa. Widely scattered (1834). Lan-a feeds in shoots of Stellaria 

uliginosa in spring. Mr. Stainton thinks it has been overlooked abroad. 

34. Anacampsis sircomella. North and West of England (1854). Perhaps a mclanic 

variety of the more widely spread A. tanioUUa. 
^n. A. immaculatella. West Wickham (1834). Unique; a distinct species. 
3G. Glyphipteryx cladiella. Eastern counties (1859). Abundant. 



324 ISLAND LIFE. [Part IL 

87. Glyphipteryx gchcmicolella. In several localities (1859). 

2)8. Gracillaria straminella, Noith Britain (1850). Perhaps a local form of the 

more southern G. elongeUa, 
89. Ornix Loganella, Scotland (1848). Abundant, and a distinct species. 
40? O. Devoniella. In Devonshire (1854). Unique. 

41. Coleophora albicosta. Widely spread (1829). Common on furze (CJiex Euro* 

pceus). May probably be found in the Northwest of France, where the food- 
plant abounds. 

42. C. mturateiia. South of England (1850). Abundant on broom. 

43. C, inflatcL South of England (1857). On Silene ir^flata, 

44. C. squamoselia. Surrey (1856). Very rare, but an obscure species. 

45. C. aa/inella. On sea-coast (1 859). Abundant. 

46. Perittia obscurepunctella. Widely scattered (1848). Larva feeds on common 

honeysuckle in July. Mr. Stainton thinks it must have been overlooked on 
the continent. 

47. ElachUta flavicomella, Dublin (1856). Excessively rare, two specimens only 

known. 

48. E. coruortella, Scotland (1854). A doubtful species. 

49. E. megerlella. Widely distributed (1854). Common. Larva feeds in grass 

during winter and early spring. 

50. E, obliquelia. Near London (1854). Unique. 

51. E, eleockariella. North and East of England (1854). An obscure form. 

52. E. subocellea. Widely distributed (1835). An obscure form ; perhaps mixed 

on the continent with other species. 

53. E. iriatomea. In chalk and limestone districts (1812). Abundant and distinct. 

54. E. (riseriatelia. South of England (1854). Very local ; an obscure species. 

55. Lit hocof lefts nigrescentella, Nortiiumberland (1850). liare ; a dark form of 

L. Bremiella^ which is widely distributed. 

56. L. irradiella. North Bntain (1854). A northern form of the more southern 

and wide-spread L. iautella. 

57. L. Iriguttel/a, Sandei-stend, near Croydon (1848). Unique; very peculiar. 
68. L. ulicioUlla, In a few wide-spread localities (1854). A peculiar form. 

59. L. Caledoniella. North Britain (1854). A local variety of the more wide-spread 

L. corylifoHella. 

60. Xr. Dunningtella, North of England (1852). A somewliat doubtful species. 

61. Bucculatrix demaryella. Widely distributed (1848). liathcr common. 

62. Tri/nrcttla squamatetla. South of England (1854). A doubtful species. 

63. T. atrifroniella. South of England, also in Lancashire (1854). Very rare and 

peculiar. 

64. Nepticula ignohUieUa. Widely scattered (1854). On hawthorn ; not common. 

65. A^. poterii. South of fingland ( 1 858). Bred from larvoj in Poterium sangutsorba. 

66. N. quinquella. South of England (1848). On oak-leaves, very local. 

67. N, apicella. Local (1854). Probably confused with allied species on the con- 

tinent. 

68. N. UeadlegtUa. Local (1854). A rare species. 

Pterophorina. 

69. Agdiitis Benntttii, East coast (1840). Common on Statice limontwn. 



Chap. XVI.] THE BRITISH ISLES. 325 

Wo have here a list of sixty-niue species, which, according to 
the best authority, are, in the present state of our knowledge, 
peculiar to Britain. It is a curious fact that only five of these 
have been described less than twenty years ago ; and as during 
all that time they have not been recognized on the continent, 
notwithstanding that good colored figures exist of almost all of 
them, it seems highly probable that many of them are really 
confined to our island. At the same time, wo must not apply 
this argument too rigidly ; for the very day before my visit to 
Mr. Stainton, he had received a letter from Professor 2feller an- 
nouncing the discovery on the continent of a species of our last 
family, Pteropliorina, which for more than forty years had been 
considered to be exclusively British. This insect, Plaiyptilia 
siiniliddctyla (Pterophoriis isodactf/lus^ Stsiinton^B "Manual"), 
had been taken rarely in the extreme nortli and south of our isl- 
ands — Teignmouth and Orkney — a fact which seemed somewhat 
indicative of its being a straggler. Again, seven of the species 
are unique — that is, have only been captured once ; and it may 
be supposed that as they are so rare as to have been found only 
once in England, they may be all equally rare and not yet found 
on the continent. But this is hardly in accordance with the 
laws of distribution. Widely scattered species are generally 
abundant in some localities; while, when a species is on the 
point of extinction, it must for a time be very rare in the single 
locality where it last maintains itself. It is then more probable 
that some of these unique species represent such as are almost 
extinct than that they have a wide range and are equally rare 
everywhere ; and the peculiarity of our insular climate, com- 
bined with our varied soil and vegetation, offers conditions which 
may favor the survival of some species with us after they have 
become extinct on the continent. 

In the list here given nine are recorded as varieties, while ten 
more, in Mr. Stainton's opinion, ought probably to be classed as 
varieties or local forms of other species, making nineteen in all. 
This leaves no less than fifty undoubted species not yet found 
beyond our islands ; and though Mr. Stainton thinks that most 
of these will ultimately be found on the continent, we can hardly 
doubt, both from general considerations dependent on the laws 



ISLAND LIFE. 



[PutU 



of dietplbiitioii, and from the peculiar liabits, eonspiciiouB ap- 
pearance, and restricted range of many of our species, tliut a 
very cousidernble nnniber will remain permanently as peculiar 
British ineects. 

Peculiarities of the hie of Man I^epidoptera. — Before quit- 
ting the Lepidoptera, it will be well to notice some very inter- 
esting examples of local modification, appareutly brought about 
by extreme conditions of CNposure and insulation, and which 
throw some light on the way in which local forms, varieties, or 
species may ho produced. This interesting phenomenon occurs 
in the Isle of Man, where Mr. Edwin Birchall lias collected 
Lepidoptera assiduously, and has discovered a number of varie- 
ties, apparently peculiar to the island, of which he has been so 
good as to send me specimens accompanied by some valuable 
notes. 

The Isle of Man has no woods, bogs, or heaths, the mountains 
being mostly covered with grass and rocks, so that a very abun- 
dant insect fauna cannot be expected. Sixteen species of butter- 
flies have been observed, and of these only one — the common 
tortoise-shell ( Vaiiesaa urticcE) — presents any peculiarity. This, 
Iiowcver, la always remarkably small, a specimen rarely being 
found to equal the smallest: English specimens ; so that we must 
look upon it as n dwarf raeo developed in tho islnnd and con- 
fined to ic. 

Tho following moths also present definite peculiarities; 
1. Apvtli laeertea. var. I'his is nrn (-niTisb-Uack color, witliliardit aiiTmnL'kinen, 

All arc alike, and are verv ilistiiR't from Ilie cominoii trpe of llie upccies, nhieli 

U nbunilniit la Wiil«j, 
a. Cirrhadia xtramptlina, var. Tliia is mucli darker nnd more ricEilj colored tlinn 

tliu English fujin, ihe j-ellnff Imtid being redooed to a nan-ow line, tKunolimcs n 

mere tlii'end. This noiild doiibileia be rcgsrdeil ns a (iistinct Rpccica if it uc- 

curicJ niili equni oonstnnc]' in some more remolo inland. 
3. Dianihtcda captupktii, i-ar. TliiMi* an exceedingly dnrk and richly mnrked form 

at tlio Irlnh 1>. capm/ikUa, ilKtf n local variety, Mr. Birclioll thinks, ■o( /J. e-ir- 

i. Z>iantkaeia tatia, var. This \» anoiher dntk form of n rnre Irlah and conliiicniiil 

J>. Ttphratia bivndularia, var. Tliis is an eTEcecdingly dark foim. nnd difleri bo muvli 
trom North uf F.nglnnd ipecimens n» lu hnvo nil ilic ni>[«Brancc of another ipo- 
cioa. Mr. Birchnll hnt hred ii from captured poreiitt, nnd fitids that the produce 
is this durk furni only. 




Chap. XVI.] THE BRITISH ISLES. 327 

We will now pass on to the Coleoptera, or beetles, an order 
which has been of late years energetically collected and carefully 
studied by British entomologists. 

List of tue Species of Beetles which, so fab as at Present Known, abb 

Confined to the Bbitisu Islands. 

CABABIDiE. 

1 . Dromius vectensis (Rye). Common in the Isle of Wight, not known elsewhere. 

2. *Hnrpalu8 latus, var, metallescens (Rye). Unique, but very marked. South 

coast. 

3. Stenolophus derelictus (Dawson). Unique. North Kent. 

IlELOrHORIDiE. 

4. ^Ochthehius Poweri (Rye). Very marked. South coast. A few specimens only. 

Brachtklttra. 

r». ^Aleochara IHhernica (Rye). Ireland. Mountain-tops. 

G. * Oxypoda rupicola (Rye). Scotland. Mountain-tops. Several specimens. 

7. * *' Edinensis (Sharp). Scotland. 

8. *' verecunda (Sharp). Scotland. 

9. ** Waterhousei (Rye). London district. 
10. Homalota eximia (Shar])). 

clavipes (Sharp). Scotland ; on mountains. Not rare. 

ohlongiuscula (Sharp). Scotland, perhaps also Swiss. 

princeps (Sharp). A coast insect. 

curtipennis (Sharp). 

eiarata (Shorp). 

puberula (Sharp). 

indiscreta (Sharp). "^ 

a/nco/or (Sharp). fSome Continental authors deny that there are 

(/*!rmana (Sharp). ( good species (Sliarp). 

setigera (Sharp). J 

Sharpi (Rye). Very marked ; unique. 

22. *Bn/oporus castaneus (Hardy and Bold). Very marked; unique. Northumber- 

land hills. 

23. *Stenu8 oscillator (Rye). Unique. South coast 

2*. *Srop(puit Ryti (Wollaston). Very distinct. Dorset coast. Several specimens. 
25. *Trogopnlaus spinicollis (Rye). Mei*sey estuary. Unique. Most distinguisha- 
ble ; nothing like it in Europe. 
2C. L^steva Shnrpi (Rye). Scotch hills. 

27. Kudectus Whitei (Sharp). Scotch hills. Probably a variety of E. Giraudi of 

Austria (the only European species) ^fif« Kraatz (Sharp). 

28. ^Homalium rugullpenne (Rye). Exceedingly marked form. Northern, western, 

and southern coasts, liare. 

rSELAPlIID^. 

20. Bryaxis cotus (Sharp). Coast. 
30. " Waterhousei {Rye). Coast. 



n. 




12. 




13. 




14. 




15. 




10. 




17. 




18. 




10. 




20. 




21. ♦ 





328 ISLAND LIFE. [Pabt IL 

81. ^Bythinta glahratus (Rjc). Sussex coast A few specimens; very distinguish- 

able ; myrmecophilous OXses \\\ ants' nests). 

TsiCHOPTERYOIDiB. 

82. Ptinelh maria (Matthews). 
38. Trichopteryx Sara ** 

34. ** Poweri ** 

35. " Edithia " 

36. ** cantiana ** 

37. ** fuBcula ** 

38. '* Kirhii ** 

39. '* fratercula '* 

40. ** Waterhousei " 

41. ** championis ** 

42. ♦* Jansoni ** 
48. '* seminitent '* 

44. '* suffocata (Halidaj). Ireland. 

45. ** dispar (Matthews). 

46. '* carbonaria (Matthews). 

47. Ptilium HaUdayi (Matthews). 

48. *' CaUdonicum (Sharp). Scotland. Very marked form. 

49. ** insigne (Matthews). 

50. Actidium concolor (Sharp). Scotland. Very marked. 

51. Ptenidium Kraatzii (Matthews). 

Anisotomidje. 

62. ^Agathidium rhinoceros (Sharp). Old fir-woods in Perthshire. Local ; many 
specimens. A very marked species. 

53. Anisotoma similaia (Rye). Uniqne. South of England. 

54. *^ lunicollis (Rye), Northeast and South of England. A very marked 
form. Several specimens. 

55. * Anisotoma clavicomis (Kye). Unique. Scotland. 

PlIALACRID.B. 

56. ^Phalacrus Brisouti (Rye). A few specimens. South of England. 

Crtptophagid-e. 

57. Atomaria Wollastoni (Sharp). Unique. Scotland. 

58. " </*risa (Rye). Unique. South of England. 

Lathrididje. 

59. Corticaria Wollastoni (Waterhouse). South coast. 

BTRRHIDiE. 

60. Syncalypta hirsuta (Sharp). 

Elaterid^. 

61. Elater coccinatus (Rye). Very marked, bnt possibly a variety of the European 

E. pranutus. South of England. 



Chap.XVLJ the BRITISH ISLES. 329 

Telephosidjs. 

C2. *Telephortis Darmnianus (Sharp). Scotland, sea-coast. A stunted form, of ab- 
normal habits. 

Ctphonidje. 

C3. Cifphon punctipennit (Sharp). Scotland. 

Amthicidje. 

64. Anthicus salinits (Crotch). South coast 

G5. * *' Scoticus (Rje). Loch Leven. Very distinct. Many specimens. 

CCRCULIONIDJS. 

C6. *Cathormiocerus maritimus (Rye). A few specimens on our south coast. A cu- 
rious genus, only found elsewhere on the coasts of the Mediterranean. 

67. *Ceuthorhynchus contractus, rar.//a///pe« (Crotch). Lundy Island. Several spec- 

imens. A curious variety only known from this island. 

68. *Lio8omu8 troglodytes (Rye). A very queer foiin. Two or three specimens. 

South of England. 

69. *Apion Jtyei (Blackburn). Shetland Islands. Several specimens. 

IIaltxcid^. 

70. Thyamis agilis (Rye). South of England. Many specimens. 

** (listinguenda {Uye), South of England. Many specimens. 

71. *Psylliodes luridipennis (Kutschern). Lundy Island. A very curious form, not 

uncommon in this small island, to which it appears to be confined. 

CoCCINELLIDA. 

72. Scymnut lividus (Bald). Northumberland. A doubtful species. 

Of the seventy-two species of beetles in the preceding list, a 
considerable number, no doubt, owe their presence there to the 
fact that they have not yet been discovered or recognized on the 
continent. This is almost certainly the case with many of those 
which have been separated from other species by very minute 
and obscure characters, and especially with the excessively mi- 
nute TrichopterygidoB described by Mr. Matthews. There are 
others, however, to which this mode of getting rid of them will 
not apply, as they are so marked as to be at once recognized by 
any competent entomologist, and often so plentiful that they can 
be easily obtained when searched for. Of this class are the 
twenty-three species whose names are marked with an asterisk 
(*), being those which, in Mr. Rye's opinion, are most likely to 
be peculiar to the localities where they are found, if any are ; 
but of this he is still somewhat sceptical. Six of these are unique, 
leaving seventeen which have occurred cither rarely or in some 



380 



ISI.AND LIFE. 



[Pabt 1L 



abnudiiiH-c. Dividing the probaLly pcculiitr species according 
to locality, we find that the South of England has produced 9, 
North o£ England 2, Scotland 6, Ireland 1, Shetland Islands 1, 
and Lundy Ishind 2. These nuinbei-a are, generally speaking, 
proportionate to the ricbnesB of the district and the amount of 
work bestowed upon it; Scotland, however, giving more than 
its dnc proportion m this reepeet, which must be imputed to its 
really possessing a gi'eatei* amonnt of speciality. The single pe- 
culiar Irish species stands as a luonnment of our comparative ig- 
norance of the entomology of the sister isle. The pccnliur spe- 
cies of Apion in the Slielland Islands is interesting, and may be 
connected ivith the very peculiar cliinatal conditions there pre- 
vailing, which liave led in some cases to a change of habits, bo 
that a species of weevil {Otiorhynchus maurus) &\viay& found on 
mountain-sides in Scotland, hero ocem-s on the sea-shore. Still 
more curious is the occurrence of two distinct forms (a species 
and a well-marked variety) on the small granitic Lundy Island 
in the Bristol Channel. This island is about three miles long, 
and twelve from the coast of Devonshire, consisting mainly of 
granite with a little of the Devonian formation, and the pres- 
ence here of peculiar insects can only be duo to isolation with 
special conditions, and immunity from enemies or competing 
forms. When we consider the similar islands off the coasts of 
Scotland and Ireland, with the Isle of Man and the Scilly Isl- 
ands, none of wliieh have been yet thoroughly explored for bee- 
tles, it is probable that many similar e:[amples of peculiar isor | 
latcd forma remain to be discovered. 

Mr. Kyo hardly thinks it possible that the Droinim vectem 
can really bo peculiar to the Isle of "Wight, although it is abua< 
dant there, and has never been found elsewhere; I)ut the cu 
of Lundy Island renders it less improbable; and when we conJ 
sider that the Aru?n ItaUcuin, Valandntha fi/h-atica, and peft 
haps one or two other plants are found nowhei-e else 
British Isles, we must admit that the same causes which havi 
acted to restrict the range of a plant may liavo had a similar ef^f 
feet witli a beetle. 

I must also notice tho Cathormtocerits mariitmus, becanse itfV 
only near ally inliabits the coasts of tho Mediterranean ; and it 



CuAP.XVL] THE BRITISH ISLES. 331 

thus offers an analogous case to the small moth, Elachista rufo- 
cinereaj which is found only in Britain and the extreme South 
of Europe. Looking then at what seems to me the probabilities 
of the case from the standpoint of evolution and natural selec- 
tion, and giving due weight to the facts of local distribution as 
they are actually presented to ns, I am forced to differ from the 
opinion held by our best entomological authorities, and to be- 
lieve that some considerable proportion of the species which in 
the present state of our knowledge appear to be peculiar to our 
islands are, not only apparently, but really, so peculiar. 

I am indebted to Mr. Robert McLachlan for the following: in- 
formation on certain Trichopterous Neuroptera, or caddis-flies, 
which appear to be confined to our islands. The peculiar aquatic 
habits of the larvse of these insects — some living in ponds or 
rivers, others in lakes, and others again only in clear mountain 
streams — render it not improbable that some of them should 
have become isolated and preserved in the mountain districts 
of our western coasts, or that they should be modified owing to 
such isolation. In these insects the characters depended on to 
separate the species are wholly structural, and the care with 
which Mr. McLachlan has studied them renders it certain that 
the species here refeiTed to are not mere varieties of known con- 
tinental forms, however closely they may resemble them in form 
and coloration. 

Tkichopteba Peculiar to the British Isles. 

1 . Setodes argentipuncteJla, — Tliis species is known only from the lakes Winder- 
mere and Killamey. It has recently been described by Mr. McLachlan, and is quite 
distinct from any known species, though allied to S, punctata and S. viridiSy which 
inhabit France and Western Euroi>e. 

2. Rhyacophila munda. — Described by Mr. McLachlan in 18G3. A very distinct 
species, found only in mountain streams in Wales and Devonshire. 

3. Philopotamus instdaris (? a variety of P. montanus). — This can hardly be 
termed a British species or variety, because, so far as at present known, it is peculiar 
to the island of Guernsey. It agrees structurally with P, montanu$^ a species found 
both in Britain and on the continent, but it differs in its strikingly yellow color, and 
less pronounced markings. AW the specimens from Guernsey are alike, and resident 
entomologists assured Mr. McLachlan that no other kind is known. Strange to say, 
some examples from Jersey differ considerably, resembling the common European 
and British form. Even should this peculiar variety be at some future time found 
on the continent, it would still be a remarkable fact that the form of insect inhabit- 



333 ISLAND LIFE. [['Anr II. 

ing two small itJands only liveiiiy miles npnrt should conscanlly difTer ; but as Jenty 
is between Guernsey nnil ilie const, it seems jiisi jiosfibte ihnt iha mora insutnr con- 
diliuns, mid pei'linps some pociilinrity uf tlio soil nnd wnter in ihc former island, liuTe 
I'enlly led to the produclion ur prvsei-ration of u well-marked rari«ty of insect. 

Za»rf and Fresh-water S/iells. — As regards the land and f resli- 
water moUiieca, it seems difficult to obtain accurate information. 
Several species Iiave been recorded as British only ; but I am 
informed by Mr, Gwyn Jefiries that most of these are decidedly 
continental, wiiile a few may be classed as varieties of continental 
Bjieeies. ATOordlng to the late Mr. Lovell Keeve, the following 
species nro peculiar to our islands; and although the lirst two 
seem exceedingly doubtful, yet the last two, to which alone we 
accord the dignity of capital type, may not improbably be pecul- 
iar to Ireland, being only found in the remote southweeteru 
mountain region, where the climate possesses in the highest 
degree the insular characteristics of a mild and uniform tem- 
perature with almost perpetual moisture, and where several of 
the peculiar Irish plants alone occur. 

1. Cgclai pisidiaidet.-^A small Lividre shell found iu cnniils. rcrlmpa 
of C. cnrweiiM or C. r, 

2. AniinUia Grai, 
on tlie banks of lii 

3. GKOXALtcus VACULOSUS.— A beautiful slug, blnck, spottsJ vrilh jellonr or 
white. It is found on rocbs on ihe shores ofLoke CuTDgh, south of Cnsllemain Bny, 
in Kerry. It wna discovered in ISiS, nnd bus never been funnd in any olher IocbI- 
iry. An allied species is fonnd in Portognl and France, uhich Mr, Uwyn Jefiriei 
IhinliB may be identical. 

4. Iauvxx itivoLUTi. — A beautiful pond-snnil witli a small polished ambcr-coloreilfl 
chell, found only in a sinnll alpine hike nnd i 

Mountain, near Ihe Lakes orKillarncy. It appears to be a very distinct gpcclea, m 
nearly allied to L. gUiiaota, wiiicli is not found in Ireland. It was discovered in 
1832, and has frequently been obtained since in the same locolily. 

The facts — that these two last-named species Lave been known i 
for about forty or fifty years respectively ; that they have neveq 
been found in any other locality than the above-named vei 
restricted stations ; nnd that they have not yet been clearly idenJ 
tified with any continental species — all point to the eonclusioifl 
that they are the last remains of peculiar forms wliicli hav^ 
everywhere else become extinct. 



—A small bivalve aheli found in en 

ico/n, according to Sir. Gwyn Jeffrie 

iiiana. — A small univalve shell allied to llie periwinkles, fonnd 

Thames lietivccn Greenwich and Giavesend, on the mud at Ura 



Chap. XVI.] THE BRITISH ISLES. 333 

Peculiarities of the British Flora. — Thinking it probable that 
there must also be some peculiar British plants, but not finding 
any enumeration of such in the British Floras of Babington, 
Hooker, or Bentham, I applied to the greatest living authority 
on the distribution of British plants, Mr. II. C. Watson, who 
has very kindly given me all the information I required, and I 
cannot do better than quote his words. He says, " It may be 
stated pretty confidently that there is no ' species ' (generally 
accepted among botanists as a good species) peculiar to the Brit- 
ish Isles. True, during the past hundred years, nominally new 
species have been named and described on British specimens 
only, from time to time. But these have gradually come to be 
identified with species described elsewhere under other names; 
or they have been reduced in rank by succeeding botanists, and 
placed or replaced as varieties of more widely distributed species. 
In his ' British Rubi,' Professor Babington includes as good spe- 
cies some half-dozen which he has, apparently, not identified 
with any foreign species or variety. None of these are accepted 
as * true species,' nor even as * sub-species,' in the ' Students' Flora,' 
where the brambles are described by Baker, a botanist well ac- 
quainted with the plants of Britain. And as all these nominal 
species of Rubi are of late creation, they have truly never been 
subjected to real or critical tests as ' species.' " 

But besides these obscure forms, about which there is so much 
difference of opinion among botanists, there arc a few flowering 
plants which, as varieties or sub-specieSy are apparently peculiar 
to our islands. These are: (1) Ileliantheninm Breweri^ an an- 
nual rock-rose found only in Anglesea and Holyhead Island 
(classed as a sub-species of IL guttatutn by Hooker and Babing- 
ton) ; (2) liosa Ilibemica^ found only in North Britain and Ire- 
land (a species long considered peculiar to the British Isles, but 
said to have been recently discovered in France) ; (3) (Enanthe 
fluviatilisy a water-drop wort, found only in the South of Eng- 
land and in one locality in Ireland (classed as a sub-species of (E. 
phellandrixim by Hooker) ; (4) Hieracium iricuin, a hawkweed 
found in North Britain and Ireland (classed by Hooker as a 
sub-species of U, Lawsotiij and said to be " confined to Great 
Britain"). 



331: ISLAND LIEE. [PutU. 

Two othef species are, so far as tlie Europenn flora is con- 
cerned, peculiar to Britaiit, being iiativce of Nortli America, 
and they are very interesting because they are certainly both 
truly indigenous ; that is, not introduced by human agency. 
These are: (1) SpirajUliea liomttmoviana, an orchid allied to 
our lady's -tresses, widely distributed in North America, but 
only found elsewhere in the extreme southwest corner of Ire- 
land : and (2) Erlocaalon 8eptangui.are^ the pipewort — a cnrlous 
North American water-plant, found in lakes in the Ilebrides and 
the West of Ireland. Along with these we may perhaps class 
the beautiful Irish filmy fern TricAomanc^ j-adicana, which in- 
liabits the Azores, Madeira, and Canary Islands, the Southwest 
of Ireland, Wales, and formerly Yorkshire, but is not certainly 
known to occur in any part of continental Europe (except, per- 
haps, the Sonthwest of Spain), though found in many tropical 
countries. 

We may liere notice the intei'estiiig fact that Ireland possesses 
no less than twenty species or sub-species of flowering plants 
not found in Britain, and some of these tna// be altogether pe- 
culiar. As a whole they show the effect of tlie pre-eminently 
mild and insular climate of Ireland in extending the range of 
some Soutli European species. The following lists of these 
plants, with a few remarks on their distribution, will be found 
interesting: 

I.19T or Imsu I'loiveuino I'lants which ark not I'oi'su is Ubitain, 

1. IMimtitmun gatialum. IrelnnJ, nenr Cotk, nnd on an island off iha coast of 

Uiilwny (iilso Chonnol Inlands, Fi'aiicc, Ilnly). 

2, Arevaria ciliatii. Soutliwcst of Irelnml (nUo AiivBrgne, Pyrenees, Crele). A 

viti'iet^r oflliie sp«cieii Im* been reconily found in PembrokeiiUire. 
8. Sanfraya nmbrovi. West of Irelnnd {x\to Nonliern fipain, I'oi'lugil). 
4. ■■ gemn. Soutlmut of Irelnnd (uliHi I'yreneei). 
fi. " hiftuta. Soutlmest of Irelnnil (nliia Pyrenees). 
6. Saxi/raga hiria (hi/pnoiJei iub-tp.). Souili of Ireland, nppnrcntly unknoivn an 



7. Inula talieiiui. West of Ireland (Middle urn] Sonili riurore). 

8. Krica 3Ueditrrranta. West oflrelnnd (West of Frnnce, Spnin, 
». •' Haetiana (ttlmliz eub-ap.) Went of IreUnd (Spnin). 

10. Arbvtiti vaah. Soutliweti of Iieliind (Nouih of KmtiM nnd .Spnin). 

11. ttaliriii-iii poli/ali-i. West of IMnnJ (We« of France nnd Spnlri)- 

VI, Pinguicvla graiiJiJiora, Southwest orirolaiid(We«HifFnince,S|wi«, Alps, etc.). 



Chap. XVI.] THE BRITISH ISLES. 335 

i;^. Neotinea intacta. West of Ireland (France, South of Europe). 

14. Spiranthea Romanzoviana. Southwest of Ireland (North America). 

Ii>. Sisyrinchium Dermwiianum. West of Ireland (? introduced; North America). 

IG. Potamogeton longifolius (JucenB var.). West of Ireland, unique specimen. 

17. ** Kirkii (natans sub-sp.). West of Ireland (Arctic Europe). 

18. Erlocaulon aeptangulare. West of Ireland, Skye, Hebrides (North America). 

1 i). Carex liuxbaumii. Northeast of Ireland, on island in Lough Neagh (Arctic and 

Alpine Europe, North America). 
20. Ciilamagi'ostis si ric ta, rar. //oo^-erl. On the shores and i>lands of Lough Neagh. 

The species occurs at one locality in Cheshire (Germany, Arctic Europe, and 

North America). 

We find Iiere nine Southwest European species which probably 
liad a wider range in mild preglacial times, and have been pre- 
served in the South and West of Ireland owing to its milder 
climate. It must be remembered that during the height of the 
glacial epoch Ireland was continental, so that these plants may 
have followed the retreating ice to their present stations and 
survived the subsequent depression. This seems more probable 
than that, so many species should have reached Ireland for the 
lirst time during the last union with the continent subsequent 
to the glacial epoch. The arctic, alpine, and American plants 
may all be examples of species which once had a wider range, 
and which, owing to the more favorable conditions, have con- 
tinued to exist in Ireland while becoming extinct in the adjacent 
parts of Britain and Western Europe. 

As contrasted with the extreme scarcity of peculiar species 
among the flowering plants, it is the more interesting and unex- 
]>ected to find a considerable number of peculiar mosses and 
Ilepatica?, some of which present us with phenomena of distri- 
bution of a very remarkable character. For the following lists 
and the information as to the distribution of the genera and 
species I am indebted to Mr. William Mitten, one of the first 
authorities on these beautiful little plants. 

List of the Species op Mosses and Hepaticje which are Pkcuuar to the 

British Isles or not found in Europe. 

{Those belonging to non- European genera in italics.) 

Mosses. 

1 . Syste^iam mtiliicapsniare Central and South England. 

2. ** Mittenii South of England. 



336 ISLAND LIFE. [Pabt II. 

3. Campylopus Slmwii North Britain. 

4. *' setifolius Ireland. 

5. Seligeria calcicola South of England. 

6. Pottia viridifolia South of England. 

7. Leptodontiiim recurvifulinm Ireland and Scotland. 

8. Tortilla Woodii Ireland. 

9. *' Hibernica Ireland. 

10. Streptopogon gemmasrtns Sussex. 

11. Grimmia subsquarrosa. North Britain. 

12. ** Siirtoni North Britain. 

13. Glyphomiirium Davicsii On basalt generally. 

14. Zygodon Nowellii North Britain. 

15. Bry iim Barnesii North Britain. 

16. Hookeria latevirens Ireland and Cornwall (also Madeira). 

1 7. Daltonia splachnoides Ireland. 

HlSPATICiE. 

1. Gymnomitrium crenulatum West of England, Ireland. 

2. Radula voluta Ireland and Wales. 

8. Acrobolbus WUsoni Ireland. 

4. Lejeunia cafi/ptri/olia Cornwall, Lake district, Ireland. 

5. ** microKopica Ireland. 

6. Lophccolea spicata Ireland. 

7. Juiigermannia cuneifolia Ireland. 

8. ** doniana Scotland. 

9. Pelalophyllum RaJfsii West Biitain, Ireland. 

Many of tlie above are minute or obscure plants, and are 
closely allied to other European species with which they may 
have been confounded. We cannot, therefore, lay any stress on 
these individually as being absent from the continent of Europe, 
80 much of which is imperfectly explored, though it is probable 
that some of them are really confined to Britain. But there are 
a few — indiciited by italics — which are in a very diflFerent cate- 
gory ; for they belong to genera which are altogether unknown 
in any other part of Europe, and their nearest allies are to be 
found in the tropics or in the Southern Hemisphere. The three 
non-European genera of mosses to which we refer all have their 
maximum of development in the Andes, while the three non- 
European IlepaticoB appear to have their maximum in the tem- 
perate regions of the Southern Hemisphere. Mr. Mitten has 
kindly furnished me with the following particulars of the dis- 
tribution of these genera : 



Chip. XVI.] THE BRITISH ISLES. 337 

Streptopogon is a comparatiyely small genus, with seven species in the Andes, 
one in the Ilimalayns, and three in the south temperate 2M>ne, besides our English 
species. 

Daltonia is ft large genus of inconspicuous mosses, having seventeen species in 
the Andes, two in Brazil, two in Mexico, one in the Galapagos, six in India and 
Ceylon, five in Java, two in Africa, and three in the antarctic islands, and one in 
Ireland. 

HooKERiA (restricting that term to the species referable to Cjclodictjon) is still a 
large genus of handsome and remarkable mosses, having twenty-six species in the 
Andes, eleven in Brazil, eight in the Antilles, one in Mexico, two in the Pacific isl- 
ands, one in New Zealand, one in Java, one in Indin, and five in Africa — besides our 
British species, which is found also in Madeira and the Azores, but in no part of 
Europe proper. 

These last two are very remarkable cases of distribution, since 
Mr. Mitten assures ine that the plants are so markedly different 
from all other mosses that they would scarcely be overlooked in 
Europe. 

The distribution of the non-European genera of Hepaticse is 
as follows : 

AcROBOLBCB. A Small genus found only in New Zealand and the adjacent isl- 
ands, besides Ireland. 

Lejeunia. a very extensive genus abounding in the tropical regions of America, 
Africa, the Indian Archipelago, and the Pacific islands, reaching to New Zealand and 
anbuctic America, sparingly represented in the British and Atlantic islands and in 
North America. 

Petalophyllum. a small genus confined to Australia and New Zenlnnd in the 
Southern Hemisphere, and Ireland in the Northern. 

We have also a moss — Myurium Hebridarum — foimil only in Scotland and the At- 
lantic islands ; and one of the Hcpaticoe — Mastitjophara Woodsii — foimd in Ireland 
and the Himalayas, the genus being most developed in New Zealand and unknown 
in any part of continental Europe. 

These are certainly very interesting facts^ but they are by no 
means so exceptional in this group of plants as to throw any 
doubt upon their accuracy. The Atlantic islands present very 
similar phenomena in the Rhamphidium purpuratum^ whose 
nearest allies are in the West Indies and South America; and 
in three species of Sciaromium, whose only allies are in New 
Zealand, Tasmania, and the Andes of Bogota. An analogous 
and equally curious fact is the occurrence in the Drontheim 
mountains, in Central Norway, of a little group of four or five 
peculiar species of mosses of the genus Mnium, which are found 

22 



»LAKD LIFE. 



an. 



nowhere else; althoiigli tlie genus extends over Europe, lotlia, 
and the Soutliern lleuiisphere, Liit always represented by a very 
few wide-ranging species except in this one mountain gronp," 

SncU facts eliow us tbe wonderful delicacy of the balance of 
conditions which determine the existence of particular species 
in any locality. The spores of mosses and HepaticiB are so mi- 
nute that they must be continually carried through the air to 
great distances, and we can hardly doubt that, so far as its pow- 
ers of difEnsion are concerned, any species which fruits freely 
might soon spread itself over tbe whole world. That they do 
not du so must depend on peculiarities of liabit and constitution, 
which lit the diEEcrent Bpeciefl for restricted stations and special 
climatic conditions ; and accoi'ding as the adaptation is more 
general, or the degree of specialization extreme, species will have 
wide or restricted ranges. Although their fossil remains have 
been i-arely detected, wc can hardly doubt that mosses have as 
high an antiquity as ferns or Lycopods; and, coupling this an- 
tiquity with their great-powers of dispersal, we may understand 
how many of the genera have come to occupy a number of de- 
tached areas scattered over the whole earth, but always such as 
afford the peculiar fonditious of climate and soil best suited to 
them. The repeated changes of temperature and other climatic 
conditions, which, as we have seen, occurred through alt the later 
geological epochs, combined with those slower changes caused 
by geographical mutations, mnet have greatly affected the dis- 
tribution of such ubiquitous yet delicately organized plants as 
mosses. Throughout countless ages they muet have been in a 
constant state of comparatively rapid migration, driven to and 
fro by every physical and organic change, often subject to mod- 
ification of structure or habit, but always seizing upon every 
available spot in which they could even temporarily raurntain 
themselves. 

Here, then, we have ft group in which there is no question of 
the means of dispersal, and where the difUeulties that present 
themselves arc not how the species reached the remote localities 
in which they are now found, but rather why they have not cs- 



n indebred lu Mr. Mitt 



Chap. XVI.] THE BRITISH ISLES. 339 

tablished themselves in many other stations which, so far as we 
can judge, seem equally suitable to them. Yet it is a carious 
fact that the phenomena of distribution actually presented by 
this group do not essentially difEer from those presented by the 
higher flowering plants which have apparently far less diffu- 
sive power, as we shall find when we come to treat of the floras 
of oceanic islands ; and we believe that the explanation of this 
is, that the life of species, and especially of genera, is often so 
prolonged as to extend over whole cycles of such terrestrial mu- 
tations as we have just referred to; and that thus the majority 
of plants are afforded means of dispersal which are usually suffi- 
cient to carry them into all suitable localities on the globe. 
Ilence it follows that their actual existence in such localities de- 
pends mainly upon vigor of constitution and adaptation to con- 
ditions, just as it does in the case of the lower and more rapidly 
diffused groups, and only partially on superior facilities for dif- 
fusion. This important principle will be used further on to af- 
ford a solution of some of the most difficult problems in the 
distribution of plant-life. 

Concluding Remarks on the Peculiarities of the British Fauna 
and Flora. — The facts, now, I believe, for thfe first time brought 
together, respecting the peculiarities of the British fauna and 
flora are sufHcient to show that there is considerable scope for 
the study of geographical distribution, even in so apparently un- 
promising a field as one of the most recent of continental islands. 
Looking at the general bearing of these facts, they prove that 
the idea so generally entertained as to the biological identity of 
the British Isles w^ith the adjacent continent is not altogether 
correct. Among birds we have undoubted peculiarities in at 
least three instances; peculiar fishes are much more numerous, 
and in this case the fact that the Irish species are all different 
from the British, and those of the Orknevs distinct from those 
of Scotland, renders it almost certain that the great majority of 
the fifteen peculiar British fishes are really peculiar, and will 
never be found on the Etiropeau continent. The mosses and 
Ilepaticoe also have been sufficiently collected in Enroi)e to ren- 
der it pretty certain that the more remarkable of the peculiar 
British forms are not found there. Why, therefore, it may well 



840 



ISLANn LIFE. 



Til. 



be asked, eIiouUI tliere not be a. proportionate number of pecul- 
iar Britisli insects! It is true that numerous species have been 
first discovered in Britain, and Bubsoquently on tbe continent; 
but we have many species which have been known for twenty, 
thirty, or forty jeure, some of which are not rare with us, and 
yet have never been found on tlie continent. We liave also 
the curious fact of our outlying islands, such as the Shetland 
Isles, the Isle of Man, and the little Lundy Island, possessing 
each some peculiar forms which certainlij do rot exist on onr 
jmncipal island, which has been so very thoroujjhly worked. 
Analogy, therefore, would lead us to conclnde that many other 
species would exist on our islands and not on the continent ; and 
wlien we find that a very large number (150), in three orders 
only, are eo recorded, we may, I think, be aura that a considera- 
ble portion of these (though how many we cannot say) are really 
endemic British species. 

The general laws of distribution also lead us to expect such 
phenomena. Very rare and very local species are such as are 
becoming extinct; and it is among insects, which are so exces- 
sively varied and abundant, which present bo many isolated 
forms, and which, dven on continents, afford numerous examples 
of very rare species confined to restricted areas, that we should 
have the best chance of meeting with every degree of rarity 
down to the point of almost complete extinction. But we know 
that in all parts of the world islands are the refuge of species 
or groups which Iiave become extinct elsewhere; and it is tlierc- 
fore in the highest degree probable that some species which 
have ceased to exist on the continent shonld be preserved in 
eomc part or other of our islands, especially as these present 
favorable climatic conditions such as do not exist elsewhere. 

There is therefore a considerable amonnt of harmony in tlie 
various facts adduced in this chapter, as well as a complete ac- 
cordance with what the laws of distribution in islands would 
lead lis to expect. In proportion to the species of birds and 
fresh-water fishes, the number of insect-forms is enormously 
great, eo that the numerous species licre recorded ns not yet 
known on the continent arc not to be wondered at; while it 
would, I think, be almost an anomaly if, with peculiar birds and 



CiLiP.XVI.] THE BRITISH ISLES. 341 

fisbos there were not a fair proportion of peculiar ineecta. Our 
entomologists should therefore give up the assumption that all 
our insects do exist on the continent, and will some time or 
other be found tliere, as not in accordance with the evidence ; 
and when this is done, and the interesting peculiarities of some 
of our smaller islands are remembered, the study of our native 
animals and plants in relation to those of other countries will 
acquire a new intei*est. The British Isles are said to consist of 
more than a thousand islands and islets. How many of these 
have ever been searched for insects? With the case of Lundy 
Island before us, who shall say that there is not yet scope for 
extensive and interesting investigations into the British fauna 
and flora 2 



ISLAND LIFE. 



CHAPTER XVn. 

BORNEO AND JAVA. 

Potiiion anil Physicnl Fealurea of Borneo.— Zoolagicnl Fonttires of Bnrreo; Mnm- 
mnlia.— Birds.— Tlie Afflnities of tiie Borncan ynuna.-Jnva, ils Piisiiion and 
I'hj'iicnl Features. ^-General Clinracier of the Fauna of Java. — DUTerenciM be- 
tivean iheFanim of Jnvn mid (hot of ilia otlicr Malay iBlnnds.— Special Rclalioiis 
ofllie Jaran Fauna to thai of ibe Asiatic Conlinont. — Fa» Geographical Cltangee 
ofjavnnnil Borneo. — TliePliilippine islands, — Concluding RcoiarksoD iIibMoIbj 



As a representative of reccut continental islands situated in 
tlio tropics, we will taiic Borneo, since, although perhuiis not 
much more ancient than Great Britain, it presents a consider- 
able amount of Epeciality, and, in its relations to the surround- 
ing islands and the Asintie continent, offers us some problems 
of great interest and considerable difficulty. 

The accompanying map ebowB that Borneo ia situated on the 
eastern side of a submarine bauk of enormous extent, being 
about 1200 miles from north to south, and 1500 from east to 
west, and embracing Java, Sumatra, and the Malnj' Peninsula. 
This vast area is all included within the 100-fathom line ; but by 
far the larger part of it — from the Gnlf of Siam to the Java 
Sea — is under fifty fathoms, or about the same depth as the sea 
that separates our own island from the continent. The distance 
from Borneo to the southern extremity of the Malay Peninsula 
is about 350 miles, and it is nearly as far from Sumatra and 
Java, while it is more than 600 miles from tlie Siamese Penin- 
sula, opposite to which its long northern coast extends. There 
18,1 believe, nowhere else npon the globe an island bo far from 
a continent, yet separated from it by so shallow a sea. Recent 
changes of sea and land must have occurred here on a grand 
scale, and this adds to the interest attaching to the study of tbia 
large island. 




i 



344 



ISLAND LIFE. 



Tlie internal geogrnpliy of Borneo is Bomewliat peculinv. A 
large portion of its surface is lowland, consisting of great allu- 
vial valleys wUieli penetrate far into the interior ; while the 
]Doiintaing, except in the north, are of no great elevation, and 
there are no extensive plateaus. A subsidence of 500 feet 
would allow the sea to fill the great valleys of the Pontianak, 
Banjerninssin, and Coti rivci-s, almost to the centre of the isl- 
and, greatly reducing its extent, and causing it to resemble in 
form the island of Celebes to tlic east of it. 

In geological structure Borneo is thoroughly continental, pos- 
eessing formations of ail ages, with basalt and crystalline rocks, 
bnt no recent volcanoes. It possesses vast beds of coal of Ter- 
tiary age; and these, no less than the great extent of alluvial 
deposits in its valleys, indicate great changes of level in recent 
geological times. 

Having thus briefly indicated those physical features of Bor- 
neo which are necessary for our iuriuiry, let us turn to the or- 
ganic world. 

Neither as regards this great island nor those which surround 
it have we the amount of detailed information in a convenient 
form tliat is required for a full elucidation of its past history. 
We have, however, a tolerable acquaintance with the two higher 
groups — mammalia and birds — both of Borneo and of all the sur- 
rounding countries, and to these alone will it be necessary to 
refer in any detail. The most convenient coui-sc, and that which 
will make the subject easiest for the reader, will be to give, 
first, a connected sketch of what is known of the zoology of 
Borneo itself, with the main conclusions to which they point; 
and then to discuss the mutual relations of some of the adjacent 
islands, and the series of geographical changes that seem re- 
quired to explain them. 

ZooLOOtCAL FeATDBEB OF BoH.VEO. 

Mammalia. — About ninety-six species of mammalia have 
been discovered in Borneo, and of these nearly two thirds are 
identical with those of the surronnding countries, and nearly 
one half with those of the continent. Among these are two 
lemurs, three civets, three cats, three deer, the tapir, the ele- 



Chap. XVIL] 



BORNEO AND JAVA. 



345 



phant, and several squirrels — an assemblage which could cer- 
tainly only have reached the country by land. The following 
species of mammalia are supposed to be peculiar to Borneo : 





QUADRUMANA. 


16. Sciuras ephippium. 




1. 


Simia morio. A small orang-outang 


17. *' 


pluto. 






with large incisor teeth. 


18. " 


macrotis. 




2^ 


Hylobates concolor. 


19. ** 


Sarawakensis. 




3. 


Kasalis larvatus. 


20. " 


Bomeonensis. 




4. 


Semnopitliecus rubicundus. 


21. 


rufogularis. 




5. 


*' chiysomelos. 


22. '* 


atricapillns. 




G. 


*' frontatus. 


23. " 


rufogaster. 




7. 


Macacos melanotus. 


24. Acantbion crassispinis. 






Cabnivora. 


25. Trichys lipara. 




8. 


Cvnogale Bennettii. 




iNBECnVORA. 




9. 
10. 
11. 
12. 


m ^9 

Paradoxarus stigmaticas. 
Ilerpestes semitorquatus. 

** brachyuras. 
Felis badia. 


26. Tupaia splendidula. 

27. " minor (Gunther, 
1876, p. 426). 

28. Dendrogale miirina. 


P. Z, o.| 


13. 


Lutra Lovii (Gtinther, P. Z. 5., 1876, 


29. Ptilocerus Lowii. 






p. 736). 




Chiroftbba. 






Unoulata. 


30. Phyllorina dorite. 




14. 


Sus barbatas. 


31. Vesperugo stenoptems. 








32. 


donaB. 






RODENTIA. 


33. " 


tjlopus. 




15. 


Pteromys plisomelas. 


34. Tapliozous aflSnis. 





Of the thirty-four peculiar species here enumerated, it is prob- 
able that when they are more carefully studied some will be 
found to be identical with those of Malacca or Sumatra ; but 
there are also four peculiar genera which are less likely to be 
discovered elsewhere. These are Nasalis, the remarkable long- 
nosed monkey ; Cynogale, a semi-aquatic civet ; Trichys, a tail- 
less porcupine ; and Ptilocerus, a feather-tailed arboreal insecti- 
vore. These peculiar forms do not, however, imply that the 
separation of the island from the continent is of very ancient 
date, for the country is so vast, and so much of the connecting 
land is covered with water, that the amount of speciality is 
hardly, if at all, greater than occurs in many continental areas 
of equal extent. This will be more evident if we consider that 
Borneo is as large as the Indo-Chinese Peninsula, or as the In- 
dian Peninsula south of Bombay ; and if either of these countries 
were separated from the continent by the submergence of the 



846 



ISLAND LIFE. 



m 



whole area north of it as far as the JlimalayRB, it would be 
foand to contain about as many peculiar geiierii anil species 
as Borneo actually does now. A more decisive test of the lapee 
of time since the separation took place is to be found in the 
presence of a number of representative species closely allied 
to those of the surrounding countries, such a& the tailed mon- 
keys and the numerous squirrels. These, however, are best seen 
anioug the birds, which have been more thoronghly collected 
and more carefully studied than the mammalia. 

Birds. — About 400 species of birds are known to inhabit 
Borneo, of which 340 are land birds. There are about 70 pe- 
culiar species; and, according to Count Salvadori, 34 of these 
(39 with Liter additions) are 'very distinct forms, while no less 
than 31 are slight moditications of species found in Sumatra or 
the Malay Peninsula. The following are the species of birds 
considered by Count Salvadori to be peculiar to Borneo, with 
the addition of a few species since added : 



t Upeda. 



\. IndlcAior Brchipelngiis. 
!. Ueleracocrjx nuglecliiB. 



I. Cevx Slinrpei. 
,. ■'• Uillnj-iii. 



UtptHeatanti SpKia. 
m\ax <OivlbJ. 

I 1. Kiiiox BomDOTieniiis. 

I 2. CiCGuba leptaeraiDmici. 
.EM ID A (Barbcts). 

I 8. CholorcB chrfsopalB. 

I 4. CulorbamlihuB futigiDosas. 
E <\Vooiip8ckerii). 

Ill, Ueniilci|ihui Ifisclieii. 
G. JimgipicDS aurnntiivcniriii. 
7. Micropternus bndiiuus. 
[,in.« (Cuckoos). 

I B, Bbcil>o<lrtes Bonieoneiitis. 



(Kingflsben). 



I II. BnlracliMtomiti nilfiperaiu. 
Caphiuclqidx (Go«igncker>). 
. CnprJmulgui arundinncetu. IBS. Cnprimultfiia Bulweri, 



Chap. XVII.] 



BORNEO AND JAVA. 



347 



FnwT flxiirvB. 
Very Diatinci Species. 



Seookd Skbiks. 
Representative Species. 



8. Delichon dasrpiis. 



IIlRUNDINIDJC (Swallows). 

I 
MusciCAPiDA (Flycatchers). 



9. 
10. 
11. 
12. 



Cvornis rafifrons. 

*' tarcosa. 

*^ beccariana. 
Schwaneria csrolata. 



13. Artnmus clemencia:. 



Ahtamida (Swallow-shrikes). 

I 

Laniidje (Shrikes). 

13. VolvociTora SchicrbraDdi. 



14. Lnnius Schwnneri. 

15. Pityriasis gymnocephala. 

NKCTARiNiiDiE (Sunbirds). 
IG. Arnchnothera crassirostris. | 

DiCEiDJC (Flower-peckers). 

14. PrioDochilos xanthopygius. 



17. Zosterops melanura. 



15. Diceam nigrimentum. 
IG. Zosterops panrala. 

PrcNONOTiDJC (Bolbuls). 



18. 
10. 
20. 

21. 



Pycnonotiis Gourdinii. 
Criniger Diardi. 
Finschii. 



4i 



Tiirdinus leucogramroiciis 
Setaria pectoralis. 

ciiiereicapilla. 



(( 



TiMALiiDJc (Babblers). 

17. Pomatorhinus Bomeonensis. 

1 8. Mixomis Bomeonensis. 

19. Drymocataphus capistratioides. 

20. Brachypterjx umbratilis. 

21. Malacocincla nxfiventris. 

PiTTiDjE (Pittas). 



24. 


Pitta BertflB. 




22. Pitta granatina. 


2r». 


** arcuata. 




23. ** Schwaneri. 


20. 


" Baudii. 




24. ** Usheri. 






Stlviidjs 


(Warblers). 


27. 


Abrornis Schwaneri. 






28. 


Prinitt superciliaris. 




25. Orthotomus Bomeonensis. 


29. 


Calamodyta donaj. 






30. 


Kittaciiiela Stricklandi. 




2G. Kittacincla suavis. 



CoBViDJE (Crows and Jays). 

27. Dendrocitta cinerascens. 

28. Platysmurus aterriroos. 



ISLAND LIFE, 



31. Mii'nfraBoi 



H'preaeatative Sprcia. 



PuAaiiNiuf (PlieoBanta). 



33. I'oljplectron cm[j1ianuiii (Itlnnd of 

I'ainwnn). 
31. P. SchlBlcrranplieri. 
5'>. LobiqphaEis Bulweri. 
SC. " caauineicouiln. 



no. Eoploe. 
SI. 
IUllid.g (Itnils). 



37. Itiilliini ruflgenis. | 

Tetbaomu* (rarlriiigea, etc.). 
3S, IletnftlOL'lyx annguinicepa. I 

39. Bnmbusicola h.'porTllira. | 

Representative forms of tho eaiiie character as these are, no 
doubt, foil lid in all extensive continental areas, but they are rarely 
6o numerous. Thus, in Mr. Elwes's paper on tlie " Bietribntion 
of Asiatic Bii-ds," lie states that 12.5 per cent, of tho land birds 
of Burniah and Tenasserini are peculiar species, whereas wo find 
that in Borneo they are about 20 per cent., and the differeneo 
may fairly be imputed to the greater proportion of slightly 
modified representative epecies due to a period of complete 
iGoIntion. Of jieculiar genera, the Indo-Chinese Peninsula has 
one — AmpelicepB, a i-emarkable yellow-crowned starling, with 
bare pink-colored orbits ; while two others, Temnarns and Cryp- 
sirliina — singular bii-ds nllietl to the jays — are found in no otlier 
part of tho Astatic continent, though they occur in some of the 
Malay Islande. Borneo has three irecnliar genera — Schwaneria, 
a flycatcher; Ileiuatortyx, a crested partridge ; andLobiophasis, 
H pjieaeant hardly distinct from Euplocamus; while two others, « 
Pityriasis, an extraordinary bare-headed bird between a jay and 
a shrike, and Carpococcyx, a pheasant-like ground-cuckoo, for- 
merly thought to be peculiar, arc said to have been discovered 
also in Sumatra. 

The insects and land shells of Borneo and of the surrounding 
countries are too imperfectly known to enable iisto arrive at any 



Chap. XVU.] BORNEO AND JAVA. 349 

accurate results with regard to their distribution. They agree, 
however, with the birds and mammals in their general approxi- 
mation to Malayan forms, but the number of peculiar species is 
perhaps larger. 

The proportion here shown of one tliird peculiar species of 
mammalia to about one fifth peculiar species of land birds teach- 
es us that the possession of the power of flight only affects the 
distribution of animals in a limited degree, and gives us confi- 
dence in the results we may arrive at in those cases where we 
have, from whatever cause, to depend on a knowledge of the 
birds alone. And the difference we here find to exist is almost 
wholly due to the wide range of certain groups of powerful 
flight — as the birds of prey, the swallows and swifts, the king- 
crows, and some others ; while the majority of forest birds ap- 
pear to remain confined, by even narrow watery barriers, to al- 
most as great an extent as do the mammalia. 

The Affinities of the Bornean Fauna. — The animals of Borneo 
exhibit an almost perfect identity in general character, and a 
close similarity in species, with those of Sumatra and the Malay 
Peninsula. So great is this resemblance that it is a question 
whether it might not be quite as great were the whole united ; 
for the extreme points of Borneo and Sumatra are 1500 miles 
apart — as far as from Madrid to Constantinople, or from Bombay 
to Rangoon. In this distance we should expect to meet with 
many local species, and even representative forms, so that we 
hardly require a lapse of time sufficient to have produced specific 
change. So far as the forms of life are concerned, Borneo, as an 
island, may be no older than Great Britain ; for the time tliat has 
elapsed since the glacial epoch would be amply sufficient to pro- 
duce such a redistribution of the species, consequent on their 
mutual relations being disturbed, as would bring the islands into 
their present zoological condition. There are, however, other 
facts to be considered, which seem to imply much greater and 
more complex revolutions than the recent separation of Borneo 
from Sumatra and the Malay Peninsula, and that these changes 
must have been spread over a considerable lapse of time. In or- 
der to understand what these changes probably were, we must 
give a brief sketch of the fauna of Java, the peculiarities of 



DLUTD UFB. 



tr- 



whieh introdace a new element into tlie qoestion tc hare to 

Jata. 

Tbe rich and beantifal island of Java, interesting alike to tlie 
poHtician, the geograplier, and the natnralist, i& more eepeciallr 
attractive to the fitndent of geographical dUtribotion, because it 
fnroiehes him with home of tlie most cnrioas anomalies and dif- 
ficult probleRU in a place where each wonld be least expected. 
As Java furuia with Hninatra one almost nnbrokcn hoc of vol- 
canoes and volcanic moimtains, iuterrnpted only by the narrow 
Strait of 8unda, wo ehould naturally expect a close resemhlance 
between tlic productions of the two islands. Bat in point of fact 
there it a much greater difference between tlicm than between 
Sumatra and Borneo, eo much farther apart, and &o very unlike 
in pliyHical features. Java differs from the three great land 
maeseii Borneo, Snmatra, and the Malay I'cninEnla far more 
tlian either of these does from each other; and this is the firet 
anomaly we encounter. But a more serious difficulty than this 
remaiUA to be stated. Java has certain close rescrahlunccs to the 
Siamese Beninaiila, and also to the Himalayas, which Borneo and 
Huinnti'ii (lu not exhibit; and, looking at the relative position of 
tlicBC lands respectively, this seems most incomprehensible. In 
order fully to appreciate tlie singalarity and difficulty of the 
problem, it will be necessary to point out the exact nature and 
umunnt of tlieso peculiarities in the fauna of Java. 

Oeiieral Charactr^r of the Fauna of Java.~li we were only 
to take account of tlic numlier of peculiar species in Java, and 
tlio relations of its fanna generally to that of tho surrounding 
lands, wo miglit pass it over as a less interesting island than Bor- 
neo or Sumatra. Its matnmnlin (ninety species) arc nearly as nu- 
merous as those of Borneo, bu*. iirc apparently less peculiar, none 
of tlio genera niid only five or six of tlie species being confined 
to ttio island. In land birds it is decidedly less ricli, having only 
270 species, (if which 40 are peculiar, and only one or two be- 
long to peculiar genera; so tliat here again the amount of spe- 
ciality is less tliHu in lioriieo. It is only when wo proceed to an- 
alyze tho species of the Javan fauna, and trace tlicir distribution 
and affinities, tlmt wo disi^over its interesting nature. 



CBAt. XVU.] 



BOBNEO ASD JAVA. 



351 



Dijft-iVHce between i/ie Fauna of Java, and that of the other 
Great Maiay Islands. — Comparing tlie fuiuia of Juva witli that 
which may be called the typical Malayan fauna as exiiibited in 
Borneo, Sumatra, and the Malay Peninsula, we find tJie follow- 
ing differences. No tcss than thirteen genera of mammalia, 
each of which is known to inhabit at least two, and generally 
all three, of the above-named Malayan conntrice, are yet totally 
absent from Java ; and they include snch important forms as the 
elephant, the tapir, and the Malay bear. It cannot be said tliat 
this difference depends on imperfect knowledge, for Java is one 
of the oldest liiiropean settlements in the East, and lias been 
explored by a long succession of Dutch and EngliBh natnralists. 
Every part of it is thoroughly well known, and it would be al- 
most as difficult to find n new mammal of any size in Europe as 
in Java. Of birds there are twenty-five genera, all typically 
Malayan, and occurring at least in two, and for the most part in 
all three, of the Malay countries, which are yet absent from Java. 
Most of these are large and conspicuous forms, such as jays, 
gapers, bee-eaters, woodpeckers, hurnbills, cuckoos, parrots, pheas- 
ants, and partridges, as impossible to have remained undiscover- 
ed in Java as the large marauialia above referred to. 

lie^ides these absent genera, there are some curious illnstra- 
tloiis of Javau isolation in the species: there being several eases 
in which the same species occurs in all three of the typical Ma- 
lay countries, while in Java it is represented by an allied species. 
Such appear to be the Malayan monkey, StminopiUwcua crista- 
tu8, replaced in Java by S. maurui ; and the large Malay deer, 
/ium equinus, represen ted in Java by H. hippeJaphug. Among 
birds there are more numerous examples, no less than seven 
species which are common to the three great Malay countries 
being represented in Java by distinct but closely allied species. 

From these facts it is impossible to doubt that Java has had a 
history of its own, quite distinct from that of the other portions 
uf the Malayan area. 

Special Jirl-ationa of tfie Jatian Fauna to that of ths Asiatic 
Contitt/mt. — These relations are indicated by comparatively few 
examples, but they are very clear and of great importance. 
Among uiauinmlia, the gcuus Helictis is found in Java, but in no 



ISLAND UFK. 



[Pah IL 



other Malay country, tliougli it inliabita also Nortli ludia ; while 
two Bpecies, Rhinoceros Javanicns and Zfpu3 Kurffmaj&TcinttWiia 
of Indo-Chinese countries and Java, but not of typical Malaya. 
Iq birdfi, there are three genera— Zootliera, ITotodelu, and Cryp- 
sirhina — which inhabit Java and Indo-China; while four others 
— Brachypteryx, AUotrina, Cochoa, and Pealtria — inhabit Java 
and the llimalayaa, but no intervening country. There are also 
two species of birds — a trogon (//a/ymcfc^ Oreskioa) and the Jav- 
anese peacock {Pavo muticm) — which inhabit only Java and the 
Indo-Chinese Peninsula. 

Here, then, we find a series of remarkable similarities between 
Java and the Asiatic continent, quite independent of tlie typical 
Malay countries, Borneo, Sumatra, and the Malay rciiinsiiln, 
which latter have evidently formed one connected land, and thus 
appear to preclude any independent union of Java and Siam. 

The great difficulty in explaining these facts ie that all the 
required clianges of sea and land must have occnrred within the 
period of existing species of mammalia. Sumatra, Borneo, and 
Malacca are, aa we have seen, almost precisely alike as regards 
their species of mammals and birds; while Java, though it dif- 
fers from them in so eurions a innnner, has no greater degree of 
speciality, since its species, when not Malayan, are almost all In- 
dian or Siamese. 

There is, however, one consideration which may help us over 
this difficulty. It seems highly probable that in tho equatorial 
regions species liave changed less rapidly than in the north tem- 
perate zone, on account of tho equality and stability of the equa- 
torial climate. "We liave seen, in Chapter X., how important an 
agent in producing extinction and modification of species must 
have been the repeated changes from cold to warm and from 
warm to cold conditions, with the inevitable migrationB and 
crowding-together that must have been their necessary conse- 
quence. But in the lowlands near the equator these changes 
would he very little felt, and thus one great cause of specific 
modification would be wanting. Let us now see whether wc 
ran sketch out a series of not iraprobabJo changes which may 
have brought about the existing relations of Java and Borneo to 
the continent. 



Chap. XVII.] BOKNEO AND JAVA. 353 

Past Geographical Changes of Java and Borneo, — Altliougli 
Java and Siiiimtra are mainly volcanic, they are by no means 
wholly 80. Sumatra possesses in its great mountain masses 
ancient crystalline rocks with much granite, while there are ex- 
tensive Tertiary deposits of Eocene age, overlying which are 
numerous beds of coal now raised up many thousand feet above 
the sea.* The volcanoes appear to have burst through these 
older mountains, and to have partly covered them, as well as 
great areas of the lowlands, with the product of their eruptions. 
In Java either the fundamental strata were less extensive and 
less i*aised above the sea, or the period of volcanic action has 
been of longer duration ; for here no crystalline rocks have been 
found except a few boulders of granite in the western part of 
the island, perhaps a relic of a formation destroyed by denuda- 
tion, or covered up by volcanic deposits. In the southern part 
of Java, however, there is an extensive range of low mountains, 
about 3000 feet high, consisting of basalt with limestone appar- 
ently of Miocene age. 

During this last-named period, then, Java would have been 
at least 3000 feet lower than it is now, and such a depression 
would probably extend to considerable parts of Sumatra and 
Borneo, so as to reduce them all to a few small islands. At 
some later period a gradual elevation occurred which ultimately 
united the whole of the islands with the continent. This may 
have continued till the glacial period of the Northern Hemi- 
sphere, during the severest part of which a few Himalayan spe- 
cies of birds and mammals may have been driven southward, 
and ranged over suitable portions of the whole area. Java was 
then separated by subsidence, and these species became im- 
prisoned there ; while those in the remaining part of the Ma- 
layan area again migrated northward when the cold had passed 
away from their former home, the equatorial forests of Borneo, 
Sumatra, and the Malay Peninsula being more especially adapted 
to the typical Malayan fauna, which is there developed in rich 
profusion. A little later the subsidence may have extended 
farther north, isolating Boraeo and Sumatra, but probably leav- 

* *' On the Geology of Sumatra," by M. R. D. M. Verbeck, Gtolwjical Mag,, 1877. 

23 



ing the Malay Peninaula ns a ridge between tbem as far as the 
islands of Banca and Biliton. Otiier sliglit elwngea of diinato 
followed, when a further siibsiJence separated these last-named 
islands from the Malay Peninsula, and left them with two or 
three species which hare since become elightty modified. Wo 
may thus explain how it is that a species is sometimes common 
to Sumatra and Borneo, while the intorveniug island (Banca) 
possesses a distinct form.' 

In my " Geographical Distribution of Animals," Vol. I., p. 357, 
I have given a somewhat different hypothetical explanation of 
the relations of Java and Borneo to the continent, in which I 
took account of changes of land and sea only; hut a fuller con- 
Bidciution of the influence of changes of climate on the migra- 
tion of animals lias led me to the much simpler, and, I think, 
more probable, explanation above given. The amount of the re- 
lationship between Java and Siam, as well as of that between 
Java and the Himalayas, is too small to be well accounted for 
by an independent geographical connection in which Borneo 
and Sumatra did not take part. It is, at the same time, too dis- 
tinct and indisputable to be ignored; and a change of climate 
which shonld drive a portion of the Himalayan fauna sooth- 
ward, leaving a few species in Java (from which they conld not 
return, owing to its subsequent isolation by eubsidencc), seems to 
bo a cause exactly adapted to produce the kind and amount of 
affinity between these distant countries that actually exist. 

The Phillj^ine Inlands. — A sufficiently detailed account of 
tlie fauna of these islands, and their relation to the countries 
which form the subject of this chapter, has been given in my 
" Geographical Distribution of Animals," Vol. I., pp. 34r}-349 ; 
hilt since that time considerable additions have been made to 
their fauna, and these have had the effect of diminishing their 
isolation from the other islands. Si-x genera have been added 
to the terrestrial mammalia — Crocidura, Felis, Ti-agnlus, Hystrix, 
Fteromys, and Mus, as well as two additional scjuirrels; while 
the black ape {VijtwpilAi'-nui niffer) has been struck out as not 



' Pilta mffiarhgnrhui (Baava), nl1i<Ml to P, &i-nrAyiini>(DornEO. Sumulrn, Mulaccn). 
nnd Pilla Baitgknn<it (ISnncn). iilliod to /*. lordidiu {Womv> lint] Siimntrn). 



Chap. XVII.] THE nilLIPPINES. 355 

inhabiting tlie Pliilippines. This brings the known mammah'a 
to twenty-one species, and no doubt several others remain to be 
discovered. The birds liavo been increased from 219 to 288 spe- 
cies, and the additions include many Malayan genera which were 
thought to be absent. Such are Phyllornis (green bulbnl) ; Eu- 
rylcemus (gaper), Malacopteron, one of tlie babblers ; and Crini- 
ger, one of the fruit-thrushes ; as well as Batrachostomus, the 
frog-mouthed goatsucker; There still remain, however, a large 
number of Malayan genera absent from the Philippines, while 
there are a few Australian and Indian or Chinese genera which 
are not Malayan. We must also note that about nine tenths of 
the mammalia and two thirds of the land birds are peculiar spe- 
cies, a very much larger proportion than is found on any other 
Malay island. 

The origin of these peculiarities is not difficult to trace. The 
Philippines are almost surrounded by deep sea, but are connected 
with Borneo by means of two narrow submarine banks, on the 
northern of which is situated Palawan, and on the southern the 
Sooloo islands. Two small groups of islands, the Bashees and 
Babuyanes, have also afforded a partial connection with the con- 
tinent by way of Formosa. It is evident that the Philippines 
once formed part of the great Malayan extension of Asia, but 
that they were separated considerably earlier than Java; and 
liaving been since greatly isolated and much broken up by vol- 
canic disturbances, their species have, for the most part, become 
modified into distinct local species. They have also received a 
few Chinese types by the route already indicated, and a few 
Australian forms, owing to their proximity to the Moluccas. 
The reason of their comparative poverty in genera and species 
of the higher animals is tliat they have been subjected to a great 
amount of submersion in recent times, greatly reducing their 
area, and causing, no doul)t, the extinction of a considerable por- 
tion of their fauna. This is not a mere hypothesis, but is sup- 
ported by direct evidence; for I am informed by Mr. Everett, 
who has made extensive explorations in the islands, that almost 
everywhere are found large tracts of elevated coral reefs con- 
taining shells similar to those living in the adjacent seas — an in- 
disputable proof of recent elevation. 



356 ISLAND LIFE. [Part IL 

Concluding Remarks cm the Malay Islands. — This completes 
our sketch of the great Malay islands, the seat of the typical 
Malayan fauna. It has been shown that the peculiarities pre- 
sented by the individual islands may be all sufficiently well ex- 
plained by a very simple and comparatively unimportant series 
of geographical changes, combined with a limited amount of 
change of climate towards the northern tropic. Beginning in 
late Miocene times, when the deposits on the south coast of Java 
were upraised, we suppose a general elevation of the whole of 
the extremely shallow seas uniting what are now Sumatra, Java, 
Borneo, and the Philippines with the Asiatic continent, and 
forming that extended equatorial area in which the typical 
Malayan fauna was developed. After a long period of stability, 
giving ample time for the specialization of so many peculiar 
types, the Philippines were firet separated ; then at a considera- 
bly later period Java ; a little later Sumatra and Borneo ; and 
finally the islands south of Singapore to Banca and Biliton. This 
one simple scries of elevations and subsidences, combined with 
the changes of climate already referred to, and such local eleva- 
tions and depressions as must undoubtedly have occurred, ap- 
pears sufficient to have brought about the curious, and at first 
sight puzzling, relations of the faunas of Java and the Philip- 
pines as compared with those of the larger islands. 

We will now pass on to the consideration of two other groups 
which offer features of special interest, and which will complete 
our illustrative survey of recent continental islands. 



CuAP.XVni.] JAPAN AND FORMOSA. 357 



CHAPTER XVIII. 

JAPAN AND FORMOSA. 

Japnn : its Position nnd Physical Features. — Zoological Features of Japan. — Mam- 
malia. — Birds. — Birds Common to Great Britain and Japan. — Birds Peculiar to 
Japan. — Japan Birds Recurring in Distant Areas. — Formosa. — Physical Features 
of Formosa. — Animal Life of Formosa. — Mammalia. — Land Birds Peculiar to 
Formosa. — Formosan Birds Recurring in India or Malaya. — Comparison of 
Faunas of Hainan, Formosa, and Japan. — General Remarks on Recent Continen- 
tal Islands. 

Japan. 

The Japanese Islands occupy a very similar position on the 
eastern shore of the great Euro- Asiatic continent to that of the 
British Islands on the western, except that they are about six- 
teen degrees farther south, and, having a greater extension in 
latitude, enjoy a more varied as well as a more temperate cli- 
mate. Their outline is also much more irregular and their 
mountains loftier, the volcanic peak of Fnsiyama being 14,177 
feet high ; while their geological structure is very complex, their 
soil extremely fertile, and their vegetation in the highest degree 
varied and beautiful. Like our own islands, too, they are con- 
nected with the continent by a marine bank less than a hundred 
fathoms below the surface — at all events, towards the north and 
south ; but in the intervening space the Sea of Japan opens out 
to a width of 600 miles, and in its central portion is very deep ; 
and this may be an indication that the connection between the 
islands and the continent is of rather ancient date. At the 
Strait of Corea the distance from the mainland is about 120 
miles, while at the northern extremity of Yesso it is about 200. 
The island of Saghalie'n, however, separated from Yesso by a 
strait only twenty -five miles wide, forms a connection with 
Amoorland in about 52° N. lat. A southern warm current flow- 
ing a little to the eastward of the islands ameliorates their cli- 
mate much in the same way as the Gulf Stream does ours, and. 



Chap. XVIII.] JAPAN AND FORMOSA. 359 

added to their insular position, enables them to support a more 
tropical vegetation and more varied forms of life than are found 
at corresponding latitudes in China. 

Zoological Featurea of Japan, — As we might expect from the 
conditions here sketched out, Japan exhibits in all its forms of 
animal life a close general resemblance to the adjacent conti- 
nent, but with a considerable element of specific individuality ; 
while it also possesses some remarkable isolated groups. It also 
exhibits indications of there having been two or more lines of 
migration at different epochs. The majority of its animals are 
related to those of the temperate or cold regions of the conti- 
nent, either as identical or allied species; but a smaller number 
have a tropical character, and these have in several instances no 
allies in China, but occur again only in Northern India or the 
Malay Archipelago. There is also a slight American element 
in the fauna of Japan, a relic probably of the period when a 
land communication existed between the two continents over 
what are now the shallow seas of Japan, Ochotsk, and Kamt- 
schatka. We will now proceed to examine the peculiarities and 
relations of the fauna. 

Mammalia, — The mammalia of Japan at present known are 
forty in number; not very many when compared with the rich 
fauna of China and Manchuria, but containing monkeys, bears, 
deer, wild goats and wild boars, as well as foxes, badgers, moles, 
squirrels, and hares, so that there can be no doubt whatever that 
they imply a land connection with the continent. No complete 
account of Japan mammals has been given by any competent zo- 
ologist since the publication of Von SieboWs " Fauna Japonica" 
in 1844 ; but by collecting together most of the scattered observa- 
tions since that period the following list has been drawn up, and 
will, it is hoped, be of use to naturalists. The species believed 
to be peculiar to Japan are printed in italics. These are very 
numerous, but it nmst be remembered that Corea and Manchu- 
ria (the portions of the continent opposite Japan) are compara- 
tively little known, while in very few cases have the species of 
Japan and of the continent been critically compared. Where 
this has been done, however, the peculiar species established by 
the older naturalists have been in many cases found to be correct. 



360 ISLAND LIFE. [Fast II 



List of the Mammalia of the Japaxese Islands. 

1. Macacta sjteciosus. A monkej with rudimentary tail and red face, allied to the 

Barbary ape. It inhabits the island of Niphon up to 41° N. lat, and has 
thus the most northern range of any living monkey. 

2. Pteropus dasymallu$, A peculiar fruit-bat, found iu Kiusiu Island only (lat. 

9^"* N.), and thus ranging farther north of the eqnator than any other species 
of the genus. 
8. Rhinoloplius ferrnm-eqninum. The great horseshoe -bat, ranges from Britain 
across Europe and temperate Asia to Japan. It is the R. nippon of the ** Fau- 
na Japonica,'* according to Mr. Dobson^s '* Monograph of Asiatic Bats." 

4. B. minor. Found also in Burmali, Yunnan, Java, Borneo, etc. 

5. Vesperugo pipistrellus. From Britain across Europe and Asia. 

6. ** abramus. Also in India and China. 

7. *' noctula. From Britain across Europe and Asia. 

8. '* molossus. Also in China. 

9. Vespertilio capaccinii. Philippine Islands and Italy. This is V, macrodactylus 

of the ** Fauna Japonica," according to Mr. Dobson. 

10. Miniopterus Schreibersii. Philippines, Burmah, Malay Islands. This is Vesper' 

tiiio blepotis of the ** Fauna Japonica." 

11. Talpa wogura. Closely resembles the common mole of Europe, but has six in- 

cisors instead of eight in the lower jaw. 

1 2. Urotrichua ta/poides. A peculiar genus of moles confined to Japan and the 

northwest const of North America. The American species has been numetl 
Urotrichus Gibsii ; but Mr. Lord, after comparing the two, says that he *' can 
find no difference whatever, cither generic or specific. In shape, size, and col- 
or they are exactly alike. 

13. Sorex mvosurus. A shrew, found also in India and Mulnva. 

1 4. Sorex dzi-nezumi, 
ir». ** umbrinus. 

ly. " plahjcephnlus, 

17. Ursns arctos, var. A peculiar variety of the European brown bear, which in- 

habits also Anioorland and Kamtschatka. It is the Ursusferox of the *' Fau- 
na Japonica." 

18. Ur&us Japonirus. A peculiar ppccies allied to the Himalayan and Formosan spe- 

cies. Named U. Tibetanus in the *' Fauna Japonica." 
10. Meles anakuma. Differs from the European and Siberian badgers in the form 
of the skull. 

20. Mustela brachynra. A peculiar marten found also in the Kurilc Islands. 

21. ** rnelampus. The Japanese sable. 

22. ** Japonica, A peculiar marten (see Proc. Zool. Soc.y 18Cr», p. 104). 

23. ** Sibericus. Also Siberia and China. This is the M. italsi of the 
** Fauna Japonica," occording to Dr. Gray. 

24. Lutronectes WInteleyi. A new genus and species of otter {Proc. Zool. Soc.^ 

18G7, p. 180). In the *' Fauna Japonica" named Lulra vit/garis. 

25. Enhydris marina. The sea-otter of California and Kamtschatka. 

26. Cam's hodophylax. According to Dr. Gray, allied to Cuon Sumatranus of the 



Chap.XVIII] japan AND FORMOSA. 361 

Malaj Islands, and C, alpinm of Siberia, if not identical with one of them 
{Proc, ZooL Soc.f 1868, p. 600). 

27. Vulpes Japonica, A peculiar fox. Cams vulpcs of ** Fauna Japonica." 

28. Nyctereutes procyonoidcs. The raccoon-dog of Northern China and Amoorland. 

29. Lepus hrachyurus, A peculiar hare. 

30. Sciunts lis. A peculiar squirrel. 

31. Pteromys leucogenys. Tlie white-cheeked flying squirrel. 

32. *' momoga. Perhaps identical with a Cambojan species {Proc. ZooL 
i&)c.,1861,p.l37). 

33. MyoTus Japonicus. A peculiar dormouse. Af. elegans of the ''Fauna Japoni- 

ca ;" M. Javanicusj Schinz (*' Synopsis Mammalium," ii., p. 530). 

34. Mus argenteus. China. 

35. *' molossinus. 

36. ** nezumi. 

37. ** speciosus. 

38. Cervus sika. A peculiar deer allied to C pseudaxis of Formosa and C. Man' 

churicus of Northern China. 
3D. Nemorhedus crispa. A goat-like antelope allied to N. Sumatranus of Sumatra, 

and N, Swinhoei of Formosa. 
40. Sm leucomystax. A wild-boar allied to S. Taivanus of Formosa. 

We thus find that no less than twenty-six out of the forty 
Japanese mammals are peenliar ; and if we omit the aerial bats 
(nine in number) as well as the marine sea-otter, we shall have 
remaining only thirty strictly land mammalia, of which twenty- 
five are peculiar, or five sixths of the whole. Nor does this rep- 
resent all their speciality ; for we have a mole differing in its 
dentition from the European mole; another closely allied to an 
American species ; a peculiar genus of otters ; and an antelope 
whose nearest allies are in Formosa and Sumatra. The impor- 
tance of these facts will be bestninderstood when we shall have 
examined the corresponding affinities of the birds of Japan. 

Birds. — Owing to the recent researches of some English resi- 
dents, we have probably a fuller knowledge of the birds than of 
the mammalia ; yet the number of true land birds ascertained 
to inliabit the islands cither as residents or migrants is only one 
hundred and sixty-five, which is less than might be expected 
considering the highly favorable conditions and the extreme 
riches of the adjacent continent — Mr. Swinhoe's list of the birds 
of China containing more than four hundred land species, after 
deducting all that are peculiar to the adjacent islands. Only 
sixteen species, or about one tenth of the whole, are now consid- 



362 



ISLAND LIFE. 



[Pakt II. 



ercd to be peculiar to Japan ; but even of these five are classed 
by Mr. Seebolira as sub-species or slightly modified forms of 
continental birds, so that eleven only are well-marked species, 
undoubtedly distinct from those of any other country. 

The great majority of the birds are decidedly temperate 
forms identical with those of Northern Asia and Europe ; while 
no less than forty of the species are also found in Britain, or are 
such slight modifications of British species that the difference is 
only perceptible to a trained ornithologist. The following list 
of the birds common to Britain and Japan is very interesting, 
when we consider that these countries are separated by the 
whole extent of the European and Asiatic continents, or by al- 
most exactly one fourth of the circumference of the globe : 



Birds Common to Great Britain and Japan.' 



1. 

2. 
3. 
4. 
6. 
6. 
7. 

8. 

J). 
10. 
11. 

12. 
13. 
14. 

ir.. 

IG. 
17. 

18. 

19. 
20. 



Common Creeper {Cert/iia /uinilia- 

ris). 
Nuthatch (Sitta Europcea), 
Coal Tit (Pants ater). 
Marsh Tit, siib-sp. (P. Juponlcus). 
Long-tailed Tit QAcredula caudata). 
Great Gray Shrike (Laniua excubitor). 
Nutcracker {Nucifraga caryocatac- 

tea). 
Carrion-crow (Corvus coroue), 
Kavcn (Corvus corar). 
Waxwing (Ampelis f/arrulus). 
Swallow, sub-sp. (Ilirundo (juttura- 

lis). 
Sand-martin (Cotyle rijmrid). 
n rambling (FringUla uiontijrinrjiUu). 
Siskin {Chrysomitris spinus). 
Lesser Hcdpole (.I'Jgiot/ius linaria'). 
Tree-sparrow {Passer ynnntanus). 
l*inc-grossbejik {PgiThula enucleatoi'). 
llced- bunting, t>ub-sp. (Embeviza 

pyrrhtilina). 
Snow-bunling (Plectrophnnes nivcdis). 
Gray AVugtail, sub-sj). {Mutacilla me- 

l(nopc). 



21. Great Spotted Woodpecker (Picus 

major), 

22. Great Black Woodpecker (Z)ryocopt« 

martius). 

23. Cuckoo (Cuculus canorus). 

24. Hoopoe (Upupa epops), 

25. ]iock-dove (Columba livid). 
2G. Hen-harrier (Circus cyuneus). 

27. Goshawk (Astur palumbiirius). 

28. Sparrow-hawk (Accipiter nisus). 

29. Uongij-legged Buzzard (Buteo iago- 

pus). 

30. Golden Kagle (Aquila chrysnetos). 

31. White- tailed Kagle (llaliirtus albi- 

cillu). 

32. Kestrel (Palco tinnunculus). 

33. Hobby (F. subbutco). 

34. Merlin (F. astdon). 

3."). Teregrine Falcon (F. peregrinus). 
3G. Greenland Falcon (F. candicans), 

37. Osprey (Pandion haliatus). 

38. Eagle-owl (Bubo maximus). 

39. Short - eared Owl (Asia acripitri- 

nus). 

40. Long-eared Owl (^4. otus). 



* Extracted from Messrs. Blakision and Fryer's *' Catalogue of Birds of Japan'' 
(Ibis^ 1878, p. 209), with Mr. Scebohm's additions and correciions (//>m, lf>79, 
p. 18). 



Chap. XVUL] JAPAN AND FORMOSA. 363 

But these forty species by no means fairly represent the 
amount of resemhlaiice between Britain and Japan as regards 
biiKls; for there are also wrens, hedge-sparrows, gold -crests, 
sedge-warblers, pipits, larks, rock-thrushes, jays, and many oth- 
ers, which, tliough distinct species from our own, have the same 
general appearance, and give a familiar aspect to the ornithol- 
ogy. There remain, however, a considerable body of Chinese 
and Siberian species, which link the islands to the neighboring 
parts of the continent ; and there are also a few which are Ma- 
layan or Himalayan rather than Chinese, and thus afford us an 
interesting problem in distribution. 

The sixteen species and sub-species which are altogether pe- 
culiar to Japan are, for the most part, allied to birds of North 
China and Siberia, but three are decidedly tropical, and one of 
them — a fruit-pigeon {Treron ISieboldi) — has no close ally nearer 
than Java and tlie Himalayas. In the following list the affini- 
ties of the species are indicated wherever they have been ascer- 
tained : 

List of the Species op Land Birds Peculiar to Japan. 

1. Parus Japonicus, A sub-species of P, palustvis, very like Siberian varieties. 

2. ** varlus. Veiy distinct. Its nearest ally is in Formosa. 

3. Ifijpsipetes amaurosis. A tropical genus. Allied to species of Sontb China and 

India. 

4. Garrulus Jajtonicus, Allied to our European jay. In Niphon only. 

r>. *' Lidthi. A very distinct and handsome species. (J?'ee Ibisy 1873, p. 

478.) 
(J. Zosterops Jnponica. Allied to a migratory Chinese species. 

7. C/ie/idon BlakUtoni. Allied to C. White'Uyi of North China. 

8. Chlorospiza Kawarahiba. Allied to C, Sinica of China and Japan. 
I). Emberiza ciopsis. A snl)-specie8 of tlie E. cioides of North China. 

10. ** Yessoensis, Allied to the Siberian JET. />aMertna. 

1 1. Enspiza variabilis. A very distinct species. 

1 2. Picus KisuL'i. Allied to P. pyrjmvtus of Central Asia. 

1:J. (mecinus awokera. Allied to (/. canus (North China) and G. riVit/w (Europe). 

1 4. Mulleripicus Richardtii. Allied to M. Crawfurdi of Pegu. In Tzus Sima Island 
(^Proc. Zool. Soc., 1870, p. 366). 

ir>. Treron Sieboldi. Allied to 71 irpA«nura (Himalayas) and 7*. JTor/Aa/st (Java). 

1(). Accipiter gularis. A sub-species of the Malayan A. virgatus (also in For- 
mosa). 

17. Buteo Hcmilasius. A distinct s|>ecies. 

1 8. Syr Ilium ru/escens. A sub-species of S. UraUnse of East Europe and Siberia. 



su 



ISLAND LIFE. 



[Part II. 



Japa?i Birds li^currinffin Distant Areas. — The most interest- 
ing feature in tlie ornithology of Japan is undoubtedly tliu pres- 
ence of several speeiea which indicate an alliance with such re- 
mote diatriets as tlio Himalayas, the Malay Islands, and Europe. 
Among the peculiar species, the most remarkable of this class 
are tlie fruit-pigeon of the genus Treron, entirely unknown in 
China, but reappearing in Formosa and Japan ; the Hypsipetes, 
whose nearest ally is in South China at a distance of nearly five 
hundred miles; and the jay {Garndus Jajxmicus), whose close 
ally {G.glandurius) inhabits Europe only, at a distance of 3700 
miles. But even more extraoi-dinary are the following non- 
peeuliar species ; — Spisastus orientalls, a crested eagle, inhabit- 
ing the Himalayas, I-'orniosa, and Japan, but unknown in Chi- 
na ; Ceryh guttata, a spotted kingfisher, entirely confined to the 
Himalayas and Japan ; and JIaleyon Coromanda, a brilliant ret] 
kingfisher inhabiting Northern India, the Halay Islands to Cel- 
ebes, Formosa, and Japan. We have here an excellent illustra- 
tion of the favonible conditions which islands afford both for 
species which elsewhere live farther south {^Ilalojon Coromunda), 
and for the preservation in isolated colonics of species wliicli 
are verging towards extinction ; for such wc must consider the 
above-named eagle and kingfisher, both confined to a very limit- 
ed area on the continent, bnt surviving in remote islands. The 
spotted kingfisher, indeed, affords ns one of the best examples of 
that raro phenomenon — a species witli a discontinuous range; 
for although an island is considered, for purposes of distribution, 
to form part of one continuous ai-ea with the adjacent continent 
(us when u species is found in France and Britain, or in Siam 
and Borneo, we do not say that the area of distribution is dia- 
continunns), yet in this case we have to pass over three thousand 
miles of hind after quitting the island, before we come to the 
continental portion of the area occupied by the species. Re- 
ferring to our account of the birth, growth, and death of a spe- 
cies (in Chapter IV.), it can hardly be doubted that the (.Wyi« 
fftillata formerly ranged from the Himalayas to Japan, and has 
now died out in the intervening area, owing to geogrnphical and 
physical changes — a subject which will be better discussed when 
we have examined the interesting fauna of the island of Formosa. 



Chap. XVIII.] JAPAN AND FORMOSA. 365 

The other ordere of animals are not yet sufficiently known to 
enable us to found any accurate conclusions upon them. The 
main facts of their distribution have already been given in my 
" Geographical Distribution of Animals" (Vol. I., pp. 227-231), 
and they sufficiently agree with the birds and mammalia in show- 
ing a mixture of temperate and tropical forms, with a considerable 
proportion of peculiar species. Owing to the comparatively easy 
passage from the northern extremity of Japan through the isl- 
and of Saghalien to the mainland of Asia, a large number of 
temperate forms of insects and birds are still able to enter the 
country, and thus diminish the proportionate number of pecul- 
iar species. In the case of mammals this is more difficult; and 
the large proportion of specific difference in their case is a good 
indication of the comparatively remote epoch at which Japan 
was finally separated from the continent. How long ago this 
separation took place we cannot, of coureo, tell, but we may bo 
sure it was much longer than in the case of our own islands, and 
therefore probably in the earlier portion of the Pliocene period. 

Formosa. 

Among recent continental islands, there is probably none that 
surpasses in interest and instructiveness the Chinese island 
named by the Portuguese Formosa, or the "Beautiful." Till 
quite recently it was a terra incognita to naturalists, and we owe 
all our present knowledge of it to a single man, the late Mr. 
Robert Swinhoe, who, in his official capacity as one of our con- 
suls in China, visited it several times between 1856 and 1866, 
besides residing on it for more than a year. During this period 
he devoted all his spare time and energy to the study of natural 
history, more especially of the two important groups, birds and 
mammals ; and by employing a large staff of native collectors 
and hunters he obtained a very complete knowledge of its fauna. 
In this case, too, we have the great advantage of a very thorough 
knowledge of the adjacent parts of the continent, in great part 
due to Mr. Swinhoc's own exertions during the twenty years of 
his service in that country. Wo possess, too, the further advan- 
tage of having the whole of the available materials in these two 
classes collected together by Mr. Swinhoe himself after full ex- 



ISLAND LIFE. 



tP*wn. 



animation and comparison of epecimene; so that there is prob- 
ably no part of the world (if we except Europe, North Araerica, 
and Bi'itieh India) of whose warm-blooded vertebrates wo pos- 
sess fuller or more accurate knowledge than we do of those of 
the coast districts of China and Its islands.' 

Physwal Features of Fonnom.— The island of Formosa is 
nearly half the size of Ireland, being 230 miles long, and from 
twenty to eighty miles wide. It is traversed down its centre by 
a fine mountain-range, which reaches an altitude of about SCit'O 
feet in the sonth and 12,000 feet in the northern half of the isl- 
and, and whose higher slopes and valleys are everywhere clothed 
with magnificent forests. It is crossed by the line of the Tropic 
of Cancer a little south of its centre; and this position, com- 
bined with its lofty mountains, gives it an unusual variety of 
tropical and temperate climates. These circumstances are all 
highly favorable to the preservation and development of animal 
life ; and, from what we already know of its productions, it seems 
probable that few, if any, islands of approximately the same size 
and equally removed from a continent will be found to equal it 
in the number and variety of their higher animals. The outline 
map on page 358 shows that Formosa is connected with the 
mainland by a submerged bank, the 100-fathoni line including 
it along with Hainan to the southwest and Japan on the north- 
east ; while the line of 200 fathoms includes also the Madjico- 
sima and Loo-choo Islands, and may perhaps mark out proxi- 
mately tlio last great extension of the Asiatic continent, the sub- 
mergence of which isolated these islands from the mainland. 

Animal Life of Formosa., — We are at present acquainted with 
35 species of mammalia and 128 species of land birds from 
Formosa, 14 of the former and 43 of the latter being pecul- 
iar, while the remainder inhabit also some part of the continent 
or adjacent islands. This proportion of peculiar species is per^ 



' Mr. Swhiliue diet] in October, I8TT, at the earlj ige of forty- Ino. Iliii writing! 
on naturiil liislar}' nre cliicHy ocnitered ilirough the Tolunm of the Procttdliiy* oflkt 
Zooloriieal Snrirli/ nnd 7^" Ibiii tlie kJioId bving iiiinmnriied in liii "Cntslajnis 
of ihfl Mammnls of South Cliinn imil FormoKs" (Piik. Xml. Soc,, 18T0, p. GIA), and 
bU"Catklogaeoftl)eBir(bofCliiaaaaditilid>u(lB"(/'nici;uB/.At>c,,ie;i,fkitS7). 



Chap. XVIIL] JAPAN AND FORMOSA. 367 

haps (as regards the birds) the highest to be met with in any 
island which can be classed as botli continental and recent, and 
this, in all probability, implies that the epoch of separation is 
somewhat remote. It was not, however, remote enough to reach 
back to a time when the continental fauna was very different 
from what it is now, for we find all the chief types of living 
Asiatic mammalia represented in this small island. Thus we 
have monkeys ; insectivora ; numerous carnivora ; pigs, deer, an- 
telopes, and cattle among ungulata; numerous rodents, and the 
edentate Manis — a very fair representation of Asiatic mammals, 
all being of known genera, and of species either absolutely iden- 
tical with some still living elsewhere, or very closely allied to 
them. The birds exhibit analogous phenomena, with the excep- 
tion that we have here two peculiar and very interesting genera. 
But besides the amount of specific and generic modification 
that has occurred, we have another indication of the lapse of 
time in the peculiar relations of a large proportion of the For- 
mosan animals, which show that a great change in the distribu- 
tion of Asiatic species must have taken place since the separa- 
tion of the island from the continent. Before pointing these 
out, it will be advantageous to give lists of the mammalia and 
peculiar birds of the island, as we shall have frequent occasion 
to refer to them. 

List of the Mammalia of Formosa. 
{The pemliar species are printed in italics.) 

1. Macacus cyclopis, A rock-monkey more allied to M. rhesus of India thnn to 

M. Sancti'Johannis of South China. 

2. Pteropus formosus. A frait-bat closelr allied to the Japanese species. None 

of tlio genus are found in China. 

3. Vcsperiigo abramus. China. 

4. Ve9pertilio formosus. Black and orange bnt. China. 

r>. Nyctinomus cestonii. Large-eared bat. China, South of Europe. 
G. Talpo insularis, A blind mole of a peculiar species. 

7. Sorcx murinus. Mnskrat. China. 

8. ** sp. A shrew, undescribed. 

9. firinaceus sp. A hedgehog, undescribed. 

10. Ursus Tibetanus. The Thibetan bear. Himalayas and North China. 

1 1 . Helictis suhaurantiaca. The orange-tinted tree-civet. Allied to //. Nipalensis 

of the Himalayas more than to JI. moschata of China. 

12. Martes flavigulfl, var. The yellow-necked marten. India, China. 



I3LXSD LITE. 



fPittT II. 



). Felii macrosoeli:!. Tlia doaded liger of Siam and Matnva. 

I. " viverriiin. The Asintic wild-cat. UJivinlnjns nnJ KLilLi::t.'a. 

I. " CliinensiB. The Chinese liger-cnL Chinn. 

i. VirerHcuIa Malaccensrs. Spotted civet- Chinn, Iildi.i. 

r. Pngumii larvata. Gem-faced civet, China. 

), Sm TaiBaatit, Allied U> the wild-pig of Jnpan. 

). Cervuliis Rcevenii. Reeve's iamitj«e. Cliiiia. 

). Crroui pieuilaiii, Formoann gpotted deer. Allied to C, Sika of Jiijinn. 

1. " Sieiphofi. Swinhoc'n Itusa deer. Allied to Indian and Mnlnyan apeeJea. 

i. NtmoThailif SwinAoti. SuioliMi goat-antelope. Allied to the species o( Su- 
matra find Jiipiin. 

t. TX<}$ Ciilnon»i«. South Cliinn ivjld-cow. 

I. Mus bnndicoin. The hnndiuoot rnt. I'eiiiapa introduced Troin India. 

>. " Indicus. Indian rnt. 

I. JIfwt coiinga. Spinous country- rat. 

'. ■' canaa. Silken counirv-rDt. 

\. " losea. Brown con nirj'-rat. 

>. Eciiimi ciistaneoTeniri*. Cbeiitint-l>«Uied Rquirrel. Clilnn and llninnn. 

I. " MacClvllnndi. MncClellntid's squiiTel. HimolnjaK, Chinn. 

. Sfiuropltrua Kateeruis. Small Foimosnii flving-Bquirrol. Allied to S. atbcuiftr 
of Nepal. 

!. PicFemift prandii. Large red Bying-Bi[uirTel. Allied to llimnliijon and Bor- 
nean tpecics. From Noitb FonnoKa- 

i, Pltromy pecioralit. While- breasted flving-fquirrel. From South Formosa. 

L Lepus Sinensis. Chinese hare. Inhabits Soaih Chinn. 

i, Mania Dalmanni. ticoly nnt-eoler. Cliina and the Iliinnlnyiis. 



The most interesting anil suggestive feature connected witii 
tlicse ForniOEan iiiammale is the identity or affinity of eeveral 
of them with Indian or Malayan rather than witli Ciiiiiese spe- 
cies. We have the rock-monkey of Formosa allied to tlie rhesiiB 
monkeys of India and Bnrniah, not to those of South China and 
Hainan, Tlie tree-civet (/leh'ctia eubatirantiaea) and tlie small 
flying-sfjuirrel {Sciuropterua Kalf^naia) are both allied to Hima- 
layan species. Swinhoe's deer and goat-antelope are nearest to 
Malayan species, as are the red and white-breasted flying-sqnir- 
rcls; while the fruitrbat, the wild-pig, and the spotted deer are 
all allied to peculiar Japanese species. Tlie clouded tiger is a 
Malay species unknown in Cliina, while the Asiatic wild-cat is 
a native of the Himalayas and Malacca. It is clear, therefore, 
that before Formosa was separated from the mainland the above- 
named animals or their ancestral types must have ranged over 
the intervening country as far as the Himalayas on tiie west, 



Chap. XVIII.] JAPAN AND FORMOSA, 369 

Japan on the north, and Borneo or the Philippines on tlie south ; 
and that, after that event occurred, the conditions were so mate- 
rially changed as to lead to the extinction of these species in 
what are now the coast provinces of China, while they or their 
modified descendants continued to exist in the dense forests of 
the Himalayas and the Malay Islands, and in such detached isl- 
ands as Formosa and Japan. We will now see what additional 
light is thrown upon this subject by an examination of the 
birds. 

List of tub Land Birds Peculiar to Formosa. 

ToRDiDA (Thrushes). 

1. Turdus albiceps. Allied to Chinese species. 

Stlviid^ (Warblers), 

2. Ciiticola volitans. Allied to C. schcenicola of India and China. 

3. Uerhivox cantans. Sub-species of U, cantUlans of North China and Japan. 

4. Notodela montium. Allied to N, leucura of the Himalayas ; no ally in China. 

TiMAUiDJS (Babblers). 

r>. Pomatorhinus musicus. Allies in South China and the Himalnvas. 
«. *' erylhrocnemis. ** " ** 

7. Garrulax ntjiceps. Allied to G. albogularis of North India and East Thibet, 

not to the species of South Ciiiiia {Q, aannio). 

8. Janthocinda pctcilorhyncha. Allied to*/, ccerulata of the Himalayas. None of 

tlic genus in China. 

9. Trochalopteron Taivanus, Allied to a Chinese species. 

10. Alcippe Morrisoniana.\ Near the Himalayan A. Nipalenais. None of tlie genus 

11. *' Brunnea. i in China. 

12. Siltia auricularis. Allied to the Himalayan S. capislrata. The genus not 

known in China. 

Panuridje (Bearded Tits, etc.). 
] 3. Suthora hulomachus. Allied to the Chinese S. suffusa, 

CiKCLiDJS (Dippers and Whistling- thrushes). 

14. Mt/iophoneus insularis. Allied to M. Ilorsjiddi of South India. 

Parida: (Tit»). 

15. Parua insperatus. Sub-species of P. monticola of the Himalayas and East 

Thibet. 

16. P. castaneoventris. Allied to P. varius of Japan. 

Liotrichida (Hill Tits). 

17. Liocichla Steerii. A peculiar genus of a specially Himalayan family, quite an- 

known in China. 

24 



370 ISLAND LIFE. [Part U. 



Pycnonotid^ (Balbals). 

] 8. Pifcnonotut (Spizixos) cinereir.apillus. Very near P, cemitorques of China. 

19. Hypsipetes nigerrimus. Allied to H. concolor of Assam, not to H. MacCleilandi 

of China. 

Oriolid^ (Orioles). 

20. Analcipus ardens. Allied to A, Traillii of the Himalayas and Tenasserim. 

Campephaoid^ (Caterpillar Shrikes). 

21. Graucaius rex-pineti. Closely allied to the Indian G. Macei, No ally in China. 

DiCRURiD^ (King Crows). 

22. Chaptia Brauniana, Closely allied to C. anea of Assam. No ally in China. 

MusciCAPiDA (Flycatchers). 

23. Cymmis vivida. Allied to C. rubeculoides of India. 

CoRViDA (Jays and Crows), 

24. Garrulus Taivanus, Allied to G^. Sinensis of South China. 

2r>. Urocissa carulea, A very distinct species from its Indian and Chinese allies. 
2G. Dendi'ocitta Formotcf, A sub-species of the Chinese Z>. Sinensis, 

Ploceid.k (Weaver Finches). 

27. Munia Formotana, Allied to M. rubronigra of India and Burroah. 

ALAtiDiOiG (Larks). 

28. Alauda Saja, > ^^j^^ .^ ^^^^^ ^^.^^^ 
20. ** WattereiJ 

PiTTlDJE (Pittas). 

30. Pitta oreas. Allied to P. cyanoptera of Mnlnya and South China. 

Picii)^. (Woodj)ecker»). 

31. Picus insularis. Allied to P, iettcofwtus of Jaimn and Siberia. 

MEOAL;KMID;f;. 

32. Megahnnn Nnrhalis, Allied to AL Oortii of Sumatra and M./aber of Hainan. 

No allies in China. 

CAPRtMCLOiD.f: (Goatsuckers). 

33. Caprimufgtts stictomua, A sub-species of C. ttwnticolus of India and China. 

CoLiTMniD.Tc (Pigeons), 

34. Treron Formoscf, Allied to Malayan species. 

S."). Sphenorercus sororius. Allied to Malayan 8j)ccic8 and to S. Sieboldi of Jnpan. 

No allies of these two birds inhabit (^hina. 
86, Chafi'ophapn Formotana* Allied to the Indian species which extends to Tenna- 

serim and Hainan. 



Chap. XVIII.] JAPAN AND FORMOSA. 371 

TKTRAONiDiE (Grouse and Partridges). 

37. Oreoperdix crudigularis. A peculiar genas of partridges. 

38. Bambuticola sonorivox. Allied to the Chinese B. ihoracica. 
3!). Areotwmix rostrata. Allied to the Chinese^. Blakistonii, 

PuASiAMiDJE (Pheasants). 

40. Phasianus Formosanus. Allied to P, torguatns of China. 

4 1 . Euplocamus Swinhoei, A very peculiar and beautiful species allied to the tropical 

fire-backed pheasants, and to the silver pheasant of North China. 

Strigid.c (Owls). 

42. Athene pardalota. Closely allied to a Chinese species. 

43. Lempigius Hamhroekii, Allied to a Chinese species. 

This list exhibits to us the marvellous fact that more than 
half the peculiar species of Formosan birds have their nearest 
allies in such remote regions as the Himalayas, South India, the 
Malay Islands, or Japan, rather than in the adjacent parts of 
the Asiatic continent. Fourteen species have Himalayan allies, 
and six of these belong to genera which are unknown in China. 
One has its nearest ally in the Nilgherries, and five in the Malay 
Islands ; and of these six, four belong to genera which are not 
Chinese. Two have their only near allies in Japan. Perhaps 
more curious still are those cases in which, though the genus is 
Chinese, the nearest allied species is to be sought for in some 
remote region. Thus, we have the Formosan babbler {Garrvlax 
rvficeps) not allied to the species found in South China, but to 
one inhabiting North India and East Thibet; while the black 
bulbul {IIyp8ipetes nigerrimus) is not allied to the Chinese spe- 
cies, but to an Assamese form. 

In the same category as the above we must place eight species 
not peculiar to Formosa, but which are Indian or Malayan in- 
stead of Chinese, so that they ojBfer examples of discontinuous 
distribution somewhat analogous to what we found to occur in 
Japan. These are enumerated in the following list: 

Species of Bihds Common to Formosa and India or Ma lata, but Not 

Found in China. 

1. Siphia superciUaris, The rufoas- breasted flycatcher of the Soatheast Hima- 

iHvas. 

2. Halcyon Coromanda, The great red kingfisher of India, Malnjn, and Jnpnn. 

8. Palutnbus pulchricolUs, The Darjeeiiog i\-ood- pigeon of the Soatheast Hima- 
layas. 



372 



ISLAND LIFE. 



i. TuraU Dus,mm,yi. TliB larger butlon-qunil of IiiJiH. 

B. Spiiictat NipaUaiii. Tlie spotted ImiYk-Engle orXejinl and j\Fi«im. 

6. LopAoi/iUa Irivirpalit. The crafted eoshawk of ifie Maliiy Islnniis. 

7. Bnlaca AViFurtwiV, Tlie brown wood-owl of tlie Hinmlnyas. 
B. Slrtji riadidit. Tho groBS-oivI of Jndia and Mnlnvii. 

The most interesting of the above are the pigeon and the fly- 
catcher, both of which are, bo far as yet known, etrictly conflncd 
to the Himalayan mountains and Formosa. They thus afford 
examiiles of discontiniions epeeitic distribution exactly parallel 
to that of tlie great spotted kingfisher, already referred to as 
fonnd only in the Himalayas and Japan. 

Comparison of the Faunas of Hainan, Formosa, and Japan, 
— Tlie island of Hainan, on the extreme sontli of China, and 
only separated from the mainland by a strait fifteen miles wide, 
appears to have considerable similarity to Formosa, inasmuch as 
it possesses seventeen peculiar land birds (out of 130 obtained 
by Mr. Swinlioe), two of wliicli aro close allies of Foruiosan spe- 
cies, while two others are identical. We also find four species 
wliose nearest allies are in the Himalayas. Our knowledge of 
this island and of the adjacent coast of China is not yet sufficient 
to enable us to form an accurate judgment of its relations, bnt it 
«;ema probable that it was separated from the continent at, np- 
pro.\imatoly, the same ei»ch as Formosa and Japan, and that 
the special features of each of tJiese islands arc mainly due to 
their gcograpliical position. Formosa, being more completely 
isolated than citlier of the others, possesses a larger proportion 
of peculiar species of birds ; while its tropical situation and lofty 
mountain-ranges have enabled it to preserve an nnusual number 
of Himalayan and Malayan forms. Japan, almost equally iso- 
lated towards tiio south, and having a much greater variety of 
climate iis well as n nmch larger area, possesses about an equal 
number of nmmniulia with Formosa, and an even larger propor- 
tion of peculiar species. Its birds, however, though more nu- 
nterouB, are less peculiar; and this is probably duo to the large 
number of species' which migrate northward in summer, and 
find it easy to enter Japan through the Kunle Isles or Sagha- 
licn. Japan, too, is largely peopled by those iiorlhern typos 
wliieh have an unusually wide range, and which, being almost 



Chap. X VIII.] JAPAN AND FORMOSA. 373 

all migratory, are accustomed to cross over seas of moderate ex- 
tent. The i*egnlar or occasional influx of these species prevents 
the formation of special insular races, such as are almost always 
produced when a portion of the population of a species remains 
for a considerable time completely isolated. We thus have ex- 
plained the curious fact that while the mammalia of the two 
islands are almost equally peculiar (those of Japan being most 
so in the present state of our knowledge), the birds of Formosa 
show a far greater number of peculiar species than those of 
Japan. 

General Remarks on Recent Continental Islands. — We have 
now briefly sketched the zoological peculiarities of an illustrative 
series of recent continental islands, commencing with one of the 
most recent — Great Britain — in which the process of formation 
of peculiar species has only just commenced, and terminating 
with Formosa, probably one of the most ancient of the series, 
and which accordingly presents us with a very large proportion of 
peculiar species, not only in its mammalia, which have no means 
of crossing 'the wide strait which separates it from the main- 
land, but also in its birds, many of which are quite able to cross 
over. 

Here, too, we obtain a glimpse of the way in which species 
die out and are replaced by others, which quite agrees with what 
the theory of evolution assures us must have occurred. On a 
continent, the process of extinction will generally take effect on 
the circumference of the area of distribution, because it is there 
that the species comes into contact with such adverse conditions 
or competing forms as prevent it from advancing farther. A 
very slight change will evidently turn the scale and cause the 
species to contract its range, and this usually goes on till it is 
reduced to a very restricted area, and finally becomes extinct. 
It may conceivably happen (and almost certainly has sometimes 
happened) that the process of restriction of range by adverse 
conditions may act in one direction only, and over a limited dis- 
trict, so as ultimately to divide the specific area into two sepa- 
rated parts, in each of which a portion of the species will con- 
tinue to maintain itself. We have seen that there is reason to 
believe that this has occurred in a very few cases both in North 



374 



ISLAND LIFE. 



Til. 



i and ill Nortticrn Asia (sec pp. 62, Gi). But the same 
tiling lins certuiiily occun-ed in a considerable nnmber of cases, 
only it lias resulted in tlie divided areas being occupied by rep- 
resentaliec forma iustend of by tbc very same species. The 
cause of this is very easy to understand. We have already 
shown that there is a large amonnt of local variation in a con- 
siderable number of species, and we may be sure that were It 
not for the const-int intermingling and intercrossing of tlie in- 
dividuals inhabiting adjacent localities, this tendency to local 
variation would soon form distinct races. But as soon as the 
area is divided into two portions, the intei'crossing is stopped, 
and the usual result is that two closely allied races, classed as 
repn^sentative species, become formed. Such pairs of allied 
species on the two sides of a continent, or in two detached areas, 
are very numerous; and their existence is only explicable on 
the snpposition that tiiey are descendants of a parent form 
which once occupied an area comprising that of both of them ; 
that this ai-ea then became discontinuous; and, lastly, that, as a 
consequence of the discontinuity, the two sections of the parent 
species became segregated into distinct races or new species. 

Now, when the division of the area leaves one portion of the 
species in an island, a similar modification of tiie species, either 
in the island or in the continent, occurs, resulting in closely al- 
lied but distinct forms; and sucli forms are, as we have seen, 
highly characteristic of island faunas. But islands also favor 
the occasional preservation of the unchanged species — a phe- 
nomenon which very rarely occurs in continents. This is prob- 
ably due to the absence of competition in islands, so that the 
parent species there maintains itself unchanged, while the conti- 
nental portion, by the force of that competition, is driven back 
to some remote mountain area, where it too obtains n compara- 
tive freedom from competition. Thus may be explained the 
cnrious fact that tlie species common to Formosa and India are 
generally confined to limited areas in the Himalayas, or in other 
cases are found only in remote islands, as Japan or Hainan. 

The distribution and atHnities of the animals of continental 
islands thus throw much light on that obscure subject— the de- 
cay and extinction of s|iccies: while tho numerous and delicate 



Chap.XVIU.] japan and FORMOSA. 875 

gradations in tho modification of the continental specieg — from 
perfect identity, through slight varieties, local forms, and insular 
races, to well-defined species and even distinct genera— afford an 
overwhelming mass of evidence in favor of the theory of " de- 
scent with modification." 

We shall now pass on to another class of islands, which, 
though originally forming parts of continents, were separated 
from them at very remote epochs. This antiquity is clearly 
manifested in their existing faunas, which present many peculi- 
arities, and offer some most curious problems to the student of 
distribution. 



376 ISLAND UFE. [Part II. 



CHAPTER XIX. 

ANCIENT CONTINENTAL ISLANDS: THE MADAGASCAR GROUP. 

Remcrks on Ancient Continental Islands. — Physical Features of Madagascar. — Bio- 
logical Featares of Madagascar. — Mammalia. — Reptiles. — Relation of Madagascar 
to Africa. — Early History of Africa and Madagascar. — Anomalies of Distribution, 
and bow to Explain them. — The Birds of Madagascar as Indicating a Supposed 
Lemurian Continent. — Submerged Islands between Madagascar and India. — Con- 
cluding Remarks on **Lemuria." — The Mascarene Islands. — The Comoro Islands. 
— The Seychelles Archipelago. — Birds of the Seychelles. — Reptiles and Amphibia. 
— Fresh -water Fishes. — Land Shells. — Mauritius, Bourbon, and Rodriguez. — 
Birds. — Extinct Birds and their Probable Origin. — Reptiles. — Flora of Madagas- 
car and the Mascarene Islands. — Curious Relations of Mascarene Plants. — En- 
demic Genera of Mauritius and Seychelles. — Fragmentary Character of tlic Mas- 
carene Flora. — Flora of Madagascar Allied to that of South Africa. — Preponder- 
ance of Ferns in the Mascarene Flora. — Concluding Remarks on the Madagascar 
Group. 

We have now to consider the phenomena presented by a veiy 
distinct chiss of islands — those which, although once forming 
part of a continent, have been separated from it at a remote 
epoch wlien its animal forms were very unlike what they are 
now. Such islands preserve to lis the record of a bygone world 
— of a period when many of the higher types had not yet come 
into existence, and when the distribution of others was very dif- 
ferent from what prevails at the present day. The problem 
presented by these ancient islands is often complicated by the 
changes they themselves have undergone since the period of 
their separation. A partial subsidence will have led to the ex- 
tinction of some of the types that were originally preserved, and 
may leave the ancient fauna in a very fragmentary state; while 
subsequent elevations may have brought it so near to the conti- 
nent that some immigration even of mammalia may have taken 
place. If these elevations and subsidences occurred several times 
over, though never to such an extent as again to unite the island 
with the continent, it is evident that a very complex result 



Chap. XIX.] THE MADAGASCAR GROUP. 377 

might be produced ; for, besides the relics of the ancient fauna, 
we might have successive immigrations from surrounding lands 
reaching down to the era of existing species. Bearing in mind 
these possible changes, we shall generally be able to arrive at a 
fair conjectural solution of the phenomena of distribution pre- 
sented by these ancient islands. 

Undoubtedly the most interesting of such islands, and that 
which exhibits their chief peculiarities in the greatest perfec- 
tion, is Madagascar, and we shall therefore enter somewhat fully 
into its biological and physical history. 

J^lujsical Features of Madagascar. — This great island is situ- 
ated about 250 miles from the east coast of Africa, and extends, 
from 12^ to 25^"" S. lat. It is almost exactly 1000 miles long, 
with an extreme width of 3G0 and an average width of more 
than 260 miles. A lofty granitic plateau, from SO to 100 miles 
wide, and from 3000 to 5000 feet high, occupies its central por- 
tion, on which rise peaks and domes of basalt and granite to a 
height of nearly 9000 feet ; and there are also numerous extinct 
volcanic cones and craters. All round the island, but especially 
developed on the south and west, are plains of a few hundred 
feet elevation, formed of rocks which are shown by their fossils 
to be of Jurassic age, or, at all events, to belong to somewhere 
near the middle portion of the Secondary period. The higher 
granitic plateau consists of bare undulating moors, while the 
lower Secondary plains are more or less wooded ; and there is 
here also a continuous belt of dense forest, varying from six or 
eight to fifty miles wide, encircling the whole island, usually at 
about thirty miles' distance from the coast, but in the northeast 
coming down to the sea-shore. 

The sea around Madagascar, when the shallow bank on which 
it stands is passed, is generally deep. This 100-fathom bank is 
only from one to three miles wide on the east side, but on the 
west it is much broader, and stretches out opposite Mozam- 
bique to a distance of about eighty miles. The Mozambique 
Channel varies from less than 500 to more than 1500 fathoms 
deep, the shallowest part being where the Comoro Islands and 
adjacent shoals seem to form stepping-stones to the continent 
of Africa. The 500 -fathom line includes Aldabra and the 



Chap. XIX.] THE MADAGASCAR GROUP. 379 

small Farquliar Islands to the north of Madagascar, while to 
the east the sea deepens rapidly to the 1000-fathoin line, and 
then more slowly, a profound cliannel of 2400 fathoms separat- 
ing Madagascar from Bourbon and Mauritius. To the north- 
east of Mauritius are a series of extensive shoals, forming four 
large banks less than 100 fathoms below the surface, while the 
1000-fathom line includes them all, with an area about half that 
of Madagascar itself. A little farther north is the Seychelles 
group, also standing on an extensive 1000-fathom bank, while 
all around the sea is more than 2000 fathoms deep. 

It seems probable, then, that to the northeast of Madagascar 
there was once a series of very large islands, separated from it 
by not very wide straits; while eastward across the Indian 
Ocean we find the Chagos and Maldive coral atolls, marking the 
position of other large islands, which together would form a line 
of communication by comparatively easy stages of 400 or 500 
miles each between Madagascar and India. These submerged 
islands, as shown in our map on page 389, are of great impor- 
tance in explaining some anomalous features in the zoology of 
this great island. 

If the rocks of Secondary age which form a belt around the 
island are held to indicate that Madagascar was once of less ex- 
tent than it is now (though this by no means necessarily fol- 
lows), we have also evidence that it has recently been considera- 
bly larger ; for along the east coast there is an extensive barrier 
coral reef about 350 miles in length, and varying in distance 
from the land from a quarter of a mile to three or four miles. 
This is good proof of recent subsidence ; while we have no rec- 
ord of raised coral rocks inland which would certainly mark 
any recent elevation, because fringing coral reefs surround a 
considerable portion of the northern, eastern, and southwestern 
coasts. We may therefore conclude that during Tertiary times 
the island was usually as large as, and often probably much 
larger than, it is now. 

Biological Features of Madagascar, — Madagascar possesses 
an exceedingly rich and beautiful fauna and flora, rivalling in 
some groups most tropical countries of equal extent, and, even 
when poor in species, of surpassing interest from the singularity, 



ISLAND LIFK. 




In lliis innp the Jcptli of tho sen is shown liv ilirec lints; i!'e lie'ne't ii"t imii'-sting 
fiom 10 ion r^iibiinij, ihc medium lint fiom lUu lo lOUO fiiltiutas, ilie cjork tint 
more tlinn 1000 rulioms. 



Chap. XIX.] THE MADAGASCAR GROUP. 381 

the isolation, or the beauty of its forms of life. In order to ex- 
liibit the fnll peculiarity of its natural history and the nature 
of the problems it offers to the biological student, we must give 
an outline of its more important animal forms in systematic 
order. 

Mammalia. — ^Madagascar possesses no less than sixty-six spe- 
cies of mammals — ^a certain proof in itself that the island has 
once formed part of a continent ; but the character of these ani- 
mals is very extraordinary and very different from the assem- 
blage now found in Africa or in any other existing continent. 
Africa is now most prominently characterized by its monkeys, 
apes, and baboons ; by its lions, leopards, and hyenas ; by its ze- 
bras, rhinoceroses, elephants, buffaloes, giraffes, and numerous 
species of antelopes. But no one of these animals, nor anything 
like them, is found in Madagascar, and thus our first impression 
would be that it could never have been united with the African 
continent. But as the tigers, the bears, the tapii*s, the deer, and 
the numerous squirrels of Asia are equally absent, there seems 
no probability of its having been united with that continent. 
Let us, then, see to what groups the mammalia of Madagascar 
belong, and where we must look for their probable allies. 

First and most important are the lemurs, consisting of six 
genera and thirty-three species, thus comprising just half the 
entire mammalian population of the island. This group of 
lowly organized and very ancient creatures still exists scattered 
over a wide area ; but they are nowhere so abundant as in the 
island of Madagascar. They are found from West Africa to 
India, Ceylon, and the Malay Archipelago, consisting of a num- 
ber of isolated genera and species, which appear to maintain 
their existence by their nocturnal and arboreal habits, and by 
haunting dense forests. It can hardly be said that the African 
forms of lemui-s are more nearly allied to those of Madagascar 
than are the Asiatic, the whole series appearing to be the discon- 
nected fragments of a once more compact and extensive group 
of animals. 

Next, we have about a dozen species of Insectivora, consisting 
of one shrew, a group distributed over all the great continents ; 
and five genera of a peculiar family, Centetidse, which family 



ISLAND LIFE. 



il'*«T II. 



exists nowhere olee on the globe except in the two largest West 
Indian islands, Cuba and Uajti, thns adding etill fiii'tlicr to our 
embarraeament in seeking for the original home of the Madar' 
gascar fnuna. 

We then come to the Carnivorn, whicli are represented by a 
peculiar cat-like animal, CrjptoproctH, forming a distinct family, 
and having no allies in any part of the globe; and eight civets 
belonging to fonr pecnliar genera. Here we lirst meet with some 
decided indications of an African origin ; for the civet family 
is more abundant in this continent than in Asia, and some of 
the Madagascar genera seem to be decidedly allied to African 
groups — as, for example, Euplerea to Snricata and Crossarchus.' 

Tiie Rodents consist only of four rata and mice of pecnliar 
genera, one of which is said to be allied to an American genus ; 
and, lastly, we have a river-hog of the African genus Potanio- 
chsems, and a small sub-fossil hippopotamns, both of which, be- 
ing sotni-aquatic animals, might easily have reached the island 
from Africa, by way of the Comoros, witliout any actual land- 
connection. 

Jieptilea of Jiadaff(Mcar.^PtiBait)g over the birds for the pres- 
ent, as not fio clearly demonstrating land-connection, let »a see 
what indications are afforded by the reptiles. The large and 
universally distributed family of Coltibrine snakes is represent- 
ed in Madagascar not by African or Asiatic genera, but by two 
American genera — Philodryss and Heterodon, and by Herpeto- 
dryas, a genns fonnd in America and China. The other genera 
are all pecnliar, and belong mostly to wide-spread tropical fami- 
lies ; but two families — L3'codontidiB and Viperida;, botJi abun- 
dant in Africa and the Eastern tropics — are absent. Lizai-ds 
are mostly represented by peculiar genera of African or tropi- 
cal families, bnt several African genera are represented by pe- 
culiar species, and there are also some species belonging to two 
American genera of the Iguanida?,a family which is exclusively 
American j while a genus of geckoes, inhabiting America and 
Anslralia, also occurs in Madagascar. 



' Sao l)r, .1. E. Griijs "l{evi^ioll ofilie VWetridec," in Pi-ocitdinf'/' itie Zoolog- 
ical Soeietj. 18IJ4. p. 007. 



Chap. XIX.] THE MADAGASCAR GROUP. 383 

Relation of Madagaacar to Africa. — These facts, taken all 
together, are certainly very extraordinary, since they show in a 
considerable number of cases as much affinity with America as 
with Africa ; while the most striking and characteristic groups 
of animals now inhabiting Africa are entirely wanting in Mad- 
agascar. Let us first deal with this fact, of the absence of so 
many of the most dominant African groups. The explanation 
of this deficiency is by no means difficult, for the rich deposits 
of fossil mammals of Miocene age in France, Germany, Greece, 
and Northwest India have demonstrated the fact that all the 
great African mammals then inhabited Europe and temperate 
Asia. We also know that a little earlier (in Eocene times) trop- 
ical Africa was cut off from Europe and Asia by a sea stretch- 
ing from the Atlantic to the Bay of Bengal, at which time 
Africa must have formed a detached island-continent such as 
Australia is now, and probably, like it, very poor in the higher 
forms of life. Coupling these two facts, the inference seems 
clear that all the higher types of mammalia were developed in 
the great Euro-Asiatic continent (which then included Northern 
Africa), and that they only migrated into tropical Africa when 
the two continents became united by the upheaval of the sea- 
bottom, probably in the latter portion of the Miocene or early 
in the Pliocene period.* 



* This view was, I believet first advanced by Professor Huxley in his "Anniver- 
sary Address to the Geological Society" in 1870. He says, **In fact, the Miocene 
mammalian fauna of Europe and the Himalayan regions contain, associated togeth- 
er, the types which are at pi-esent separately located in the South African and Indian 
provinces of Arctogo^a. Now there is every reason to believe, on other grounds, that 
both Hindostan south of the Ganges, and Africa south of the Sahara, were separated 
by a wide sea from Europe and North Asia during the Middle and Upper Eocene 
epochs. Hence it becomes highly probable that the well-known similarities, and no 
less remarkable differences, between the present faunae of India and South Africa 
have aiiscn in some such fiishion as the following. Some time during the Miocene 
epoch, the bottom of the nummulitic sea was upheaved and converted into dry land 
in the direction of a line extending from Abyssinia to the mouth of the Ganges. By 
this means the Dekkan, on the one hand, and South Africa, on the other, became con- 
nected nirh the Miocene drv land and with one another. The Miocene mammals 
spread gradually over this intermediate dry land; and if the condition of its eastern 
and western ends offei*ed as wide contrasts as the valleys of the Ganges and Arabia 
do now, many forms which made their way into Africa must have been different 



It is clear, tlierefore, tliat if Madagascar Ijad once formed part 
of Africa, but had been separated from it bufure Africa was 
united to Europe and Asia, it would not contain any of those 
kinds of nnlmals which then first entered the conntry. But, 
besides the African mammals, we know that some birds now 
contiiied to Africa tRen inhabited Europe, and we may therefore 
fnirly ussumo that all the more important groups of birds, I'ep- 
ti!c», and insects, now abundant in Africa, but absent from Mad- 
agascar, formed no part of the original African fauna, hut en- 
tered the country only after it was joined to Europe and Asia, 

Eiirh/ Iliatori/ of AfvU'.a, and Maiiag(iscar.—\fe have seen 
that Madagascar contains an abundance of iiiamnialB, aud that 
most of them are of types either peculiar to, or existing also in, 
Africa; it follows that that continent must have had an earlier 
union with Europe, Asia, or America, or it could never have ol>- 
tnined any ninmuials at all. Kow tlieso ancient African mam- 
mals are Leuiui's, Insectivora, aud small Carnivora, chiefly Viver- 
ridiB ; and all these groups are knowm to liavo inhabited Europe 
ill Eocene and Miocene times; and that the unioa was with 
Europe rather than with America is clearly proved by the fact 
that even the Insectivorous Ceutctidie, now coutined to Mada- 
gascar and the West Indies, inhabited France in tlie Lower 
Miocene period; while the ViverridiE, or civets, which form so 
important a part of the fauna of Madagascar as well as of Afri- 
ca, were abundaut iu Euiupe throughout tlio whole Tertiary 
period, but are not known to have ever lived in any part of the 
American continent. "Wo here see the application of the prio- 
ciple which wo have already fully proved and illustrated (Chap- 
ter IV., p. 61), that all extensive groups have a wide range at 
the period of their maximum development; but as they decay 



fl'oni llio»e wlik'h reoclieil llic nekknn, while others miglit ]Kin inio botli (liew inli- 
provinew." 

This question is full; discussed in my " Geografihlcnl DiKtrihulJoii of Atkimnls" 
(Vol. I., p. 38.'i), wlicre I expreucd views somewhat difi'ei'oiit frum thuso or i'rofensoT 
Hiixlev. nnd iimde some alight eiTors wiiiuh nre torrecied in iho presonntnik, A*l 
dill not then rorer lo Hrufewnr IloKlev's prior atittement of ihe llieorv ofMiiicene im- 
niigrntion into Africa (wliicli I iiiid rand, but the reference lo whicb 1 eould not rs> 
call), I am hniipy lu t{iva hii \ien'8 hero. 




Chap. XIX.] THE MADAGASCAR GROUP. 385 

their area of distribntion diminishes or breaks up into detached 
fragments, which one after another disappear till the group be- 
comes extinct. Those animal forms which we now find isolated 
ill Madagascar and other remote portions of the globe all belong 
to ancient groups which are in a decaying or nearly extinct con- 
dition, while those which are absent from *t belong to more re- 
cent and more highly developed types, which range over exten- 
sive and continuous areas, but have had no opportunity of reach- 
ing the more ancient continental islands. 

Anomalies of DiMrihution^ and how to Explain them. — If these 
considerations have any weight, it follows that there is no rea- 
son whatever for supposing any former direct connection be- 
tween Madagascar and the Greater Antilles merely because the 
Insectivorous Centetidse now exist only in these two groups of 
islands; for we know that the ancestors of this family must 
once have had a much wider range, which almost certainly ex- 
tended over the groat northern continents. Wc might as rea- 
sonably suppose a land-connection across the Pacific to account 
for the camels of Asia having their nearest existing allies in the 
llamas and alpacas of the Peioivian Andes, and another between 
Sumatra and Brazil, in order that the ancestral tapir of ono 
country might have passed over to the other. In both these ' 
cases we have ample proof of the former wide extension of the 
group. Extinct camels of numerous species abounded in North 
America in Miocene, Pliocene, and even Post -pliocene times, 
and one has also been found in Northwestern India, but none 
whatever among all the rich deposits of mammalia in Europe. 
We are thus told, as clearly as possible, that from the North 
American continent as a centre the camel tribe spread west- 
ward, over now-6ubmerged land at the shallow Behring Strait 
and Kamtschatka Sea into Asia, and southward along the Andes 
into South America. Tapira are even more interesting and in- 
structive. Their remotest known ancestors appear in Western 
Europe in the early portion of the Eocene period ; in the later 
Eocene and the Miocene other forms occur both in Europe and 
North America. These seem to have become extinct in North 
America, while in Europe they developed largely into many 
forms of true tapirs, which at a much later period found their 

25 



ISLAND UVK. 



[PunU. 



way again to North and tlieiiee to South America, where their 
remains are found in eaves and gravel-deposits. It is nn in- 
structive fact that in the Eastern continent, where they were 
once 80 abundant, they have dwindled down to a single species. 
existing in flinall niimberg in the Malay Penineula, Sumatra, and 
Borneo only; while* in the Western continent, where they arc 
comparatively recent immigrants, they occupy a much larger 
area, and are represented by three or four distinct species. Who 
could possibly have imagined such migrations, and extinctions, 
and changes of distribution as are demonstrated in the case of 
the tapirs if we had only the distribution of the existing species 
to found an opinion upon i Such cases as these — and there are 
many others equally striking — show ua with the greatest dis- 
tinctness how nature has worked in bringing about the exam- 
ples of anomalouB distribution that everywhere meet us; and 
we must, on every ground of philosophy and common-sense, 
apply the same method of interpretation to the more nnnieroua 
instances of anomalous distribution we discover among such 
gi-oups as reptiles, birds, and insects, where we rarely have any 
direct evidence of their past migrations through the discovery 
of fossil i-cmains. Whenever we can trace the past liistory of 
any group of terrestrial animals, wc invariably iind that its 
actual distribution can be explained by migrations effected by 
means of comparatively slight modifications of our existing con- 
tinents. In no single case have we any direct evidence that the 
distribution of land and sea has been radically changed during 
the whole lapse of the Tertiary and Secondary periods, while, 
as we have already shown iu onr tifth chapter, the testimony 
of geology itself, if fairly interpreted, upholds the same theory 
of the stability of our continents and the permanence of our 
oceans. Yet so easy and pleasant is it to specnlafe on former 
changes of land and sea with which to cut the Gordian knot 
offered by anomalies of distribution that M'e still continually 
meet with suggestions of former continents stretching in every 
direction across the deepest oceans, in oi-der to explain the pres- 
ence in remote parts of the globe of the same genera even of 
plants or of insects — organisms which possess such exceptional 
facilities both for terrestrial, aerial, and oceanic transport, and of 



Chap. XIX.] THE MADAGASCAR GKOUP. 387 

whose distribution in past ages we generally know absolutely 
nothing. 

The Birds of Madagascar as Indicating a Supposed Leinu- 
rian Cmitinent — Having thus shown how the distribution of 
the land mammalia and reptiles of Madagascar may be well ex- 
plained by the supposition of a union with Africa before the 
greater part of its existing fauna had reached it, we have now 
to consider whether, as some ornithologists think, the distribu- 
tion and affinities of the birds present an insuperable objection 
to this view, and require the adoption of a hypothetical conti- 
nent — Lemuria — extending from Madagascar to Ceylon and the 
Malay Islands. 

There are about one hundred land birds known from the isl- 
and of Madagascar, all but four or five being peculiar ; and 
about half of these peculiar species belong to peculiar genera, 
many of which are extremely isolated, so that it is often diffi- 
cult to class tliera in any of the recognized families, or to de- 
termine their affinities to any living birds. Among the other 
moiety, belonging to known genera, we find fifteen which have 
undoubted African affinities, while five or six are as decidedly 
Oriental, the genera or nearest allied species being found in In- 
dia or the Malay Islands. It is on the presence of these pecul- 
iar Indian types that Dr. Hartlaub, in his recent work on the 
" Birds of Madagascar and the Adjacent Islands," lays great 
stress, as proving the former existence of "Lemuria;" while 
he considers the absence of such peculiar African families as 
the plantain-eaters, glossy-starlings, ox-peckers, barbets, honey- 
guides, hombills, and bustards, besides a host of peculiar Af- 
rican genera, as sufficiently disproving the statement in my "Ge- 
ographical Distribution of Animals" that Madagascar is "more 
nearly related to the Ethiopian than to any other region," and 
that its fauna was evidently " mainly derived from Africa." 

But the absence of the numerous peculiar groups of African 
birds is so exactly parallel to the same phenomenon among mam- 
mals that we are justified in imputing it to the same cause, the 
more especially as some of the very groups that are wanting — 
the plantain-eatera and the trogons, for example — are actually 
known to have inhabited Europe along with the large mamma- 



ISLAND LIFE. 



[Piar II. 



lia w]iicli subsequently migrated to Africa. As to tlm peculiarly 
Eastern genera — siicli as Copsycbus and llypsipetes, witli a Di- 
cnirue, Ploccus, a Oisticoln, and a ^^cops, all closely allied to In- 
dian or Malayan species — althougli very strikiug to tlio orni- 
thologist, tlioy certainly do not outweigh the fourteen African 
genera found in ifadagascar. Their presence may, moreover, 
bo accounted for more satisfactorily tlian by means of an an- 
cient Leinurian continent, wliicli, even if granted, would not ex- 
plain the very facts adduced in its support. 

Let ua firet prove this latter statement. 

The supposed "Lemuria" ninst have existed, if at all, at so 
remote a period that the higher animals did nut then inhabit 
either Africa or Southern Asia, and it must have become par- 
tially or wholly submerged before tbey reached those countries; 
otherwise wo should find in Madagascar many other iiiiimala 
besides I-emure, Insectivora, and Viverridie, especially sneU ac- 
tive arboreal creatures as monkeys and squirrels, such hardy 
grazers as doer or antelopes, or such wide-ranging carnivores as 
foxes or bears. This obliges us to date the disappearance of 
the hypothetical continent about the earlier part of the Miocene 
epoch nt latest, for during the latter part of that period we 
know that such animals existed in abundance in every part of 
the great northern continents wherever we have found organic 
remains. But the Oriental birds in Madagascar, by whose pres- 
ence Dr. ITartlanb upholds the theory of a Lenmria, are slightly 
modified forms of existing Indian genera, or Bometimes, as Dr. 
Ilartlaub himself points out, species hardlij distinguishabli'. from 
thone of India. Now all tlie evidence at our command leads 
u8 to conclude that, even if these genera and species wore in 
existence in the early Miocene period, tJiey must have had a 
widely different distribution from what they have now. Ahmg 
with so many African and Indian genem of mammals, they then 
probably inhabited Europe, which at that epoch enjoyed a sub- 
tropical climate; and this is rendered almost certain by the dis- 
covery in the Miocene of France of fossil remains of trogona 
and jungle-fowl. If, then, these Indian birds date back to the 
very period during which alone Lemuria could have existed, 
that continent was quite unnecessary for their introiluction into 



i^U. 



CHir. XIX.} 



THE MADAGASCAlt GllOtJI'. 



Madagascar, as tliey conM have followed tlie same track as the 
mammalia of Miocene Europe and Asia; while if, as I main- 
tain, they ni-e of more recent date, then I^mnria liad ceased to 
esist, and conld not have been tlie means of their introduction. 




Submerged Idwnds iciween Madoffoscar and India. — Look- 
ing at the Accompanying map of the Indian Ocean, we gee that 
between Madagascar and India there are now extensive shoals 
and coral reefs, such as are always lield to indicate subsidence ; 
iiiid we may therefore fairly j»ostnlate the former existence hei'c 
of several large islands, some of them not much inferior to 
Madagascar itself. These reefs arc all separated from each other 
by very deep sea — mnch deeper than that wliicli divides Mada- 
gascar from Africa, and wo have tlierefore no reason to imagine 
their former nnion. Bnt they wunld. neverthulese, greatly facili- 
tate tlie introdnctton of Indian birds into the Maecarenc Islands 
and Madagascar ; and these facilities existing, such an iminigra- 



ISLAND LIFE. 



tO. 



tioii woiiKI be sure to tiike place, just as surely as American 
birds iiave entered tlie Galapagos and Junn Fernandez, a& Euro- 
pean Iiiitis now reach tlie Azores, and as Australian birds reach 
Biieh a distant island as New Zealand, This wonid take place 
the more certainly because the Indian Ocean is a region of vio- 
lent periodical storms at the changes of the monsoons, and we 
have seen in the case of the Azores and Bermnda Low impor- 
tant a fai:tor this is in determining the transport of birds across 
the ocean. 

Mr. Darwin's theory of tho fornjation of atolls is now almost 
universally accepted as the true one, and this theory implies 
that the arciis in question are still, or have very recently been, 
subsiding. The final disappearance of these now sunken islands 
does not, therefore, iu all pi'obability, date back to a very remote 
epoch; and this exactly at-cords with the fact that some of the 
birds, as well as the frnit-bats of tho genus Pteropus, are very 
closely allied to Indian species, if not actually identical, others 
being distinct species of the same genera. The fact that not 
one closely allied species or even genua of Indian or Malayan 
mammals is found in Madagascar eufBciently ])roves that it is 
no land-connection that has brought about this sjnall infusion of 
Indian birds and bats; while we have sufficiently shown that, 
when we go back to remote geological times, no land-connection 
in this direction was necessary to explain the phenomena of the 
distribution of the Lemurs and Inseetivora. A land-connection 
with some continent was undoubtedly neeessnry, or there would 
have been no mammalia at all in Madagascar; and the nature 
of its fauna, on the whole, no less than the moderate depth of 
the intervening strait and the eomparativD approximation of the 
opposite shores, clearly indicate that the connection was with 
Africa, 

CondutViiiij Itemarlf^ on " Lemnria." — I have gone into this 
question in some detail, because Dr. Hartlaul/e criticism on my 
views has been reproduced in a seientific periodical,' and the 
supposed licmurian continent is constantly referred to by <]uasi- 
scientitic writers, as well as by natnnilists and geologists, as if its 



Chap. XIX.] THE MADAGASCAR GROUP. 391 

existence had been demonstrated by facts, or as if it were abso- 
lutely necessary to postulate such a land in order to account for 
the entire series of phenomena connected with the Madagascar 
fauna, and especially with the distribution of the Lemuridae/ 
I think I have now shown, on the other hand, that it was essen- 
tially a provisional hypothesis, very useful in calling attention 
to a remarkable series of problems in geographical distribution, 
but not affording the true solution of those problems, any more 
than the hypothesis of an Atlantis solved the problems present- 
ed by the Atlantic Islands and the relations of the European 
and North American flora and fauna. The Atlantis is now rare- 
ly introduced seriously except by the absolutely uuscientitic, hav- 
ing received its death-blow by the chapter on Oceanic Islands in 
the " Origin of Species," and the researches of Professor Asa 
Gray on the affinities of the North American and Asiatic floi^as. 
But " Lemuria" still keeps its place — a good example of the sur- 
vival of a provisional hypothesis which offers what seems an 
easy solution of a diflieult problem, and has received an appro- 
priate and easily remembered name, long after it has been proved 
to be untenable. 

It is now more than four yeare since I first showed, by a care- 
ful examination of all the facts to be accounted for, that the 



» In a paper read before the Geological Society in 1874, Mr. II. F. Blanford, 
from the Himihirity of the fossil plants and reptiles, supposed that India and South 
Africa had been connected by a continent, **and remained so connected with some 
short intervals from the Permian up to the end of the Miocene period,'* and Mr. 
Woodward expressed his satisfaction with ''this further evidence derived from the 
fossil flora of tlie Mesozoic series of India in con'oboration of the former existence 
of an old submerged continent — Lemuria." 

Those who have read the preceding chapters of the present work will not need to 
have pointed out to them how utterly inconclusive is the fragmentary evidence de- 
rived from such remote periods (even if there were no evidence on the other side) as 
indicating geographical changes. The notion that a similarity in the productions of 
widely separated continents at any past epoch is only to be explained by the exist- 
ence of a direct land-connection, is entirely opposed to all that we know of the wide 
and varying distribution of all types at different periods, as well as to the great pow> 
crs of dispersal over moderate widths of ocean possessed by all animals except mam- 
malia. It is no less opposed to what is now known of the general permanency of the 
l^reat continental and oceanic areas ; while in this particular case it is totally incon- 
^istent (as has been shown above) with the actual facts of the distribution of animals. 



399 



ISLAND LIFE. 



[PiBT n. 



Iiypotliesis of a Lenniriaii continent was .ilike unnecessary to ex- 
plain one portion of the facts, and inadequate to explain the re- 
inuining portion.' Since that time I have seen no attempt even 
to discuss the question on general grounds in opposition to my 
views, nor, on the other liand, have those who have hitherto 
supported the hypothesis taken nny opportunity of acknowledg- 
ing its weakness and inutility. I iiave therefore here explained 
uiy i-easons for rejecting it somewhat more fully and in a more 
popular form, in the hope thjit a cheek may thus be placed on 
the continued restatement of this unsound tlieory us if it were 
one of tlie accepted conclusions of modern Bcience. 

The Jfascarene /glands'— In the " Geographical Distribntion 
of Animals," a summary is given of all that was known of the 
zoology of the various islands near Madagascar, which to some 
extent partake of its peculiarities, and with it form tlie Malagasy 
sub-region of tiie Ethiopian region. As no great additions havo 
since been made to our knowledge of the fauna of these inlands, 
and my object in this voiume being more especially to illustrate 
the mode of solving distrihutional problems by means of the 
most suitable examples, 1 shall now confine myself to pointing 
nut how far the fads presented by these outlying islands sup- 
port the views already enunciated with regard to the origin of 
the Madagascar ftuina. 

The Comoro Islaiuls. — This group of islands is situated nearly 
midway between the northern extremity of Madagascar and tlie 
coast of Africa. The four chief islands vary between sixteen 
and forty miles in length, the largest being ISO miles from llie 
const of Africa, while one or two smaller islets are less than 
100 miles from Madagascar. All are volcanic, Great Comoro 
being an active volcano 8500 feet high ; and, as already stated, 
they are situated on a submarine bank with less than .'lOO fath- 
oms soundings, oouuecting Madagascar with Africa. There is 
reason to believe, however, that these islands are of compara- 
tively i-ecent origin, and that the bank has been formed by mat- 



' " Oeogrnpliicnl DiMribnlion of Animnis," Vol. L.p- S72-29S. 
' The term " Mnscai'ene " ii used here in an e.'clenileil icnie lo incliiile nil ilie isl- 
mill* ncai' Mndngnscnr nliidi resemble it in tlieir nniinnl .ind vogctabla jiroiliii-iioiii. 



Chap. XIX.] THE MADAGASCAR GROUP. 393 

ter ejected by the volcanoes or by upheaval. Anyhow, there is 
no indication whatever of there having been here a land-con- 
nection between Madagascar and Africa, while the islands them- 
selves have been mainly colonized from Madagascar, to the 100- 
fathom bank surrounding which some of them make a near ap- 
proach. 

The Comoros contain two land mammals, a lemur and a civet, 
both of Madagascar genera and the latter an identical species, 
and there is also a peculiar species of fruit-bat {Pteropus Como- 
renms\ a group which ranges from Australia to Asia and Mada- 
gascar, but is unknown in Africa. Of land birds forty-one spe- 
cies are known, of which sixteen are peculiar to the islands, 
twenty-one are found also in Madagascar, and three found in 
Africa and not in Madagascar ; while of tlu3 peculiar species six 
belong to Madagascar or Mascarene genera. 

These facts point to the conclusion that the Comoro Islands 
have been formerly more nearly connected with Madagascar 
than they are now, probably by means of intervening islets and 
the former extension of the latter island to the westward, as in- 
dicated by the extensive shallow bank at its northern extrcm- - 
ity, so as to allow of the easy passage of birds, and the occasion- 
al transmission of small mammalia by means of floating trees.* 

The ISei/chellea Archipelago. — This interesting group consists 
of about thirty small islands situated 700 miles N.N.E. of Mada- 
gascar, or almost exactly in the line formed by continuing the 
centi-al ridge of that great island. The Seychelles stand upon a 
rather extensive shallow bank, the 100-fathom line around them 
enclosing an area nearly 200 miles long by 100 miles wide, while 
the 500-fathom line shows an extension of nearly 100 miles in a 
southern direction. All the larger islands are of granite, with 
mountains rising to 3000 feet in Mahe, and to from 1000 to 
2000 feet in several of the other islands. We can therefore 
hardly doubt that they form a portion of the great line of up- 
heaval which produced the central granitic mass of Madagascar, 
intervening points being indicated by the Amirantes, the Provi- 



* For the birds of the Comoro I.^lnnd?, see Proceedings of the Zoological Society^ 
1877, p. 295, and 1879, p. G73. 



ISLAND LIFIi:. 



[I'ARi ir. 



dence, ami the Fai-quliar lelands, wliicli. iboitgh all cornUine, 
probably rest on a gi'anitic ba&is. Deep cbannek of mure tlian 
1000 fathoms now aeiiarate tlicse lelnnds from each otlicr, and i£ 
they were ever aufficicntly elevated to be united, it was probably 
at ft very remote epoeb. 

Tile Seyehelles may tluia have had ample facilities for receiv- 
ing from Madagascar such immigrants as can pass over narrow 
eeae; and, on the other hand, tliey were eqmilly favorably elta- 
iited as rcgai-ds the exteneive !^aya do Mnllta and Cargados banks, 
which were probably once large islands, and may iiave supported 
a rich insular flora and fauna of mixed Mascarene and Indian 
type. The existing fnniia and flora of the Seychelles must there- 
fore be looked npon an the remnants wliich have Bnrvived the 
partial submergence of a very exteneive island ; and the entire 
absence of mammalia may be due either to this island having 
never been actually united to Madagascar, or to its having since 
undergone so much submergence as to have led to the extinc- 
tion of such mammals as may once have inhabited it. The birds 
and reptiles, liowever, thoufrh few in number, are very interest- 
ing, and tlirow some further light on the past history of the 
Seychelles. 

Blrd^ of f/te Seyelu.-U<'8. — Fifteen indigenous land birds are 
known to inhabit the gronp, thirteen of wliich are peculiar spe- 
cies,' belonging to genera which occur also in Madagascar or 
Africa. The genera which are more peculiarly Indian are, Cop- 
sychus and Idypsipetes, also found in Madagascar; and PalBe- 
ornis, which has species in Hanritius and Kodrigiiez, as well 
as one on the continpnt of Africa. A black parrot (Goracopsia), 
congeneric with two species that inhabit Madagascar and with 



■ '['he fulloiving U a lis! at tlicsc peculini 
and IHIII, JbD;]: 

KUiiin Seycliollenaii. 
Coptj'chu* Sovcliellanim. 
llfiwipctBi criiisinMiTit. 
Tcliitre* i'orvina. 
N«ctnriiita Ilunuirieri. 
ZotMrop* moileiin. 

FoiiJiii Nojclicllnriiin. 



Iiii'dii (>«e Itie Hit fur tRI!7, p. 8u9i 



CuLVituA 
Alectornnini pulclierriinut. 
'I'unur RHtniiiu. 

Tiimanciiliiii p^cilifc 




CuAP. XIX.] THE MADAGASCAR GROUP. 395 

one tliat is peculiar to the Comoros ; and a beautiful red-headed 
blue pigeon {Alectorcencut pidcfierrimxi^) allied to those of Mad- 
agascar and Mauritius, but very distinct, are the most remarka- 
ble species characteristic of this group of islands. 

Reptiles and Amphibia of the Seychelles. — The reptiles and 
amphibia are rather numerous and very interesting, indicating 
clearly that the islands can hardly be classed as oceanic. There 
are five species of lizards, three being peculiar to the islands, 
while the two others have a rather wide range. The first is a 
chameleon — a defenceless slow-moving lizard, especially abundant 
in Madagascar, from which no less than twenty-one species are 
now known, about the same number as on the continent of Af- 
rica. Tiie Seychelles species {Chanieleo tigris) is peculiar to the 
islands. The next is one of the skinks {Eaprepes cyanoga8ter\ 
small ground-lizards with a very wide distribution in the Eastern 
Hemisphere. This species is, however, peculiar to the islands. 
The other peculiar species is one of the geckoes {Phelsuma Set/- 
chellefisis). An East African species (P. cepedianus) is also found 
in the Seychelles, as well as in the Comoro Islands, Bourbon, 
Mauritius, Madagascar, and Ilodriguez ; and there is also a third 
gecko of another genus {Peropus mutilatm) which is found also 
in Mauritius, Bourbon, Rodriguez, and Ceylon, and even in 
Penang and the Philippine Islands. These lizards, clinging as 
they do to trees and timber, are exceedingly liable to be carried 
in ships from one country to another, and I am told by Dr. 
GUnther that some are found almost every year in the London 
Docks. It is therefore probable that when species of this fam- 
ily have a very wide range they have been assisted in their mi- 
grations by man, though their habit of clinging to trees also rcn- 
tlere them likely to be floated with large pieces of timber to con- 
siderable distances. Dr. Percival Wright, to whom I am in- 
debted for much information on the productions of the Sey- 
chelle Archipelago, informs me that the last-named species 
varies greatly in color in the different islands, so that he could 
always tell from which particular island a specimen had been 
brought. This is analogous to the curious fact of certain lizards 
on the small islands in the Mediterranean being always very 
different in color from those of tlic mainland, usually becoming 



BLAND LIFE. 



CPaiit ir. 



rleli blue or black (see Nature, Vol. XIX., p. 97); and we thus 
learn bow readily in some cases differencea of color are brought 
about by local conditions. 

Snakes, aa is usually tbe case in 8rii,ill or remote islands, are 
far less niimorous than lizards, only two species being known. 
One, Dromieus Sirychellensis, is » peculiar species of the family 
Colubridte, the rest of tbe genus being found in Madagascar and 
South America. The other, Boodon. geometricus, one of the 
Lycodontidie, or fanged ground-snakes, inhabits also South and 
West Africa. So far, then, as the reptiles are concerned, there 
is nothing bnt what is easily explicable by what we know of the 
general means of distribution of these animals. 

We now come to the amphibia, which are represented iu the 
Seychelles by two tailless and two serpent -like forms, Tho 
frogs are, I^ana Maacar'tenmH, found also in Mauritius, Bourbon, 
Angol.% and Abyssinia, and probably all over tropical Africa ; 
and Megali^aliia infrarufiis, a tree-frog altogether peculiar to 
the islands, and forming a peculiar genus of the wide-spread 
tropical family Polypedatidte. It is found. Dr. Wright informs 
inc, on the Pundani, or screw-pines; and as these form a ve\y 
characteristic portion of tlie vegetation of the Mascavene Islands, 
all the species being peculiar and coufined each tu a single isl- 
and or small group, we may perhaps consider it as a relic of the 
indigenous fauna of that more extensive land of which tlie pres- 
ent islands are the remains. 

Tho serpentine amphibia are represented by two epeciea of 
Cfficilin. These creatures externally resemble large worms, ex- 
cept that they have a true head with jaws and rudimentary 
eyes, while intoraally they have, of coui-sc, a true vertebrate skel- 
eton. They live underground, burrewing by means of the ring- 
like folds of the skin, whicli simulatQ the jointed aegnients of a 
■worm's body ; and when caught they exude a viscid slime. The 
young have external gills which are afterwai-ds replaced by triio 
lungs, and this peculiar metamorphosis shows that thcr belong; 
to tho amphibia rather than to the reptiles, Tije Camellias are 
widely but very sparingly distributed through all the tropical 
regions — a fact which may, as we have seen, bo taken as an in- 
dication of the great antiipiity of the group, and that it is now 



Chap. XIX.] THE MADAGASCAR GUOUP. 397 

verging towards extinction. In the Seychelle Islands two spe- 
cies have been found, named respectively Ccecilia oxyura and 
C. ro8traia. The former also inhabits the Malabar coast of 
India, while the latter has been found in West Africa and also 
South America.* Tliis is certainly one of the most remarkable 
cases of the wide and discontinuous distribution of a species ^ 
known ; and when we consider the habits of life of these ani- 
mals, and the extreme slowness with which it is likely they can 
migrate into new areas, we can hardly arrive at any other con- 
clusion than that this species once had an almost world-wide 
range, and that in the process of dying out it has been left 
stranded, as it were, in these three remote portions of the globe. 
The extreme stability and long persistence of specific form 
which this implies is exti*aordinary, but not unprecedented, 
among the lower vertebrates. The crocodiles of the Eocene 
period diflfer but slightly from those of the present day, while a 
small fresh-water turtle from the Miocene deposits of the Siwalik 
Hills is absolutely identical with a still living Indian species, 
Emya tectus. The mud-lish of Australia, Ceratodus Forsterij is 
a very ancient type, and may well have remained specifically 
unchanged since early Tertiary times. It is not, therefore, in- 
credible that the Seychelles C(6cilia may be the oldest land 
vertebrate now living on the globe — dating back to the early 
part of the Tertiary period, when the warm climate of the 
Northern Hemisphere in high latitudes, and the union of the 
Asiatic and American continents, allowed of the migration of 
such types over the whole Northern Hemisphere, from which 
they subsequently passed into the Southern Hemisphere, main- 
taining themselves only in certain limited areas where the phys- 
ical conditions were especially favorable, or where they Were 
saved from the attacks of enemies or the competition of higher 
forms. 
Frtsh-waUr Ftsfves, — The only other vertebrates in the Sey- 

* Specimens nre recorded from West Africa in the Proceedingn of the Academy of 
Natural Science^ Pliilndelpliin, 1857, p. 72, while specimens in the I'nris Museum 
were brought by D'Orbigny from South America. Dr. Wright's s|)ecimcns from the 
Seychelles hnve, ns he informs me, been determined to be the same species by Dr. 
Peters, of Berlin. 



I&IiAHD IrlFS. 



[paei ir. 



chellee ai-e two fresh-water fishes abounding in the streams and 
rivHleta, One, IliiplochUus Playfairli, is peculiar to the islands, 
but tliei-o are allied species in Madagascar. It is a pretty little 
Jieh about four inches long, of an olive color, with rows of red 
spots, and is very abundant in some of the mountain streams. 
The iishes of this genus, as I am iuformed by Dr. Giinther, often 
inhabit both aea and freph water, so tliat their migration from 
Madagascar to the Seychelles and subsequent modilication offer 
no diliiculty. The other species is Fundulua orthonotus, found 
also on the east coast of Africa ; and as both belong to the same 
family — Cyprinodontidie — this may possibly have migrated in a 
similar manner. 

IaxwI Sftdla. — The only other group of animals inhabiting the 
Seychelles which we know with any approach to completeness 
are the iand and fresli-water mollusca, but they do not furnish 
any facts of special interest. About forty species are known ; and 
Mr, Geoffrey Nevill, who has studied them, thinks their meagre 
number is chiefly owing to the destniction of so much of the 
forests which once covered the islands. Seven of the species — 
and among them one of the luost conspicuous, Achalina fulica 
— have almost certainly been introdneed; and the remainder 
show a mixture of Madagascar and Indian forms, with a prepon- 
derance of the latter. Five genera — Streptaxis, Cyiithoponea, 
Onchidiuni, Helicina, and I'aludonius — arc mentioned as being 
especially Indian, while only two — Tropidophora and Gibbus — 
are found in Madagasc-ar, but not in India.' About two thirds 
of the species appear to be peculiar to the islands. 

Mauritius, jSoufbim, and Rodrigties. — These three islands are 
somewhat out of place in this chapter because they really belong 
to the oceanic group, being of volcanic formation, surrounded by 
deep sea, and possessing no indigenous mammals or amphibia. 
Tet their productions are so closely related to those of lladngas- 
car, to which they may be considered as attendant satclliteti, that 
it is absolutely necessary to associate them together if wc wish 
to comprehend and explain their many interesting features. 



' " A'litiiiunnI Noten on ilie f^inrl Slivlli of Hie SFydiKlle UlnmlH," by Geoffi^ 
Koiill. C.M.Z.S.. ill Proetediagi Bflhe Zuolnffiral Sorifty, I8C», [i. 01. 



Chap. XIX.] THE MADAGASCAR GROUP. 399 

Mauritius and Bourbon arc lofty volcanic islands, evidently of 
great antiquity. They are about 100 miles apart, and the sea be- 
tween them is less than 1000 fathoms deep, while on each side 
it sinks rapidly to depths of 2400 and 2600 fathoms. We have 
therefore no reason to believe that they have ever been connect- 
ed ^vith Madagascar, and this view is strongly supported by the 
character of their indigenous fauna. Of this, however, we have 
not a very complete or accurate knowledge, for though both isl- 
ands have long been occupied by Europeans, the study of their 
natural products was for a long time greatly neglected, and, ow- 
ing to the rapid spread of sugar cultivation, tlie virgin forests, 
and with them, no doubt, many native animals, have been almost 
wholly destroyed. There is, however, no good evidence of there 
ever having been any indigenous mammals or amphibia, though 
both are now found and are often recorded among the native 
animals.* 

The smaller and more remote Eodriguez is also volcanic ; but 
it has, besides, a good deal of coralline rock — an indication of par- 
tial submergence, and helping to account for the poverty of its 
fauna and flora. It stands on a 100-fathom bank of considerable 
extent, but beyond this the sea rapidly deepens to more than 

' In Maillnrd's ** Notes sur Tile de Reunion/' n considerable number of ranrnmnlia 
are given ns ** wild/' such as Lemur mongoz and Centetes selosus, botli Mndn^isvar 
species, with such undoubtedly introduced animnls as a wild-cat, a linrc, and several 
mts and mice. He also gives two species of frogs, seven lizards, and two snakes. 
The latter are both Indian species and certainly imported, as are most probably the 
frogs. Legouat, who resided some years in the island nearly two centuries ago, and 
who was a close observer of nature, mentions numerous birds, large bats, land tor- 
toises, and lizards, but no other reptiles or venomous animals except scorpions. We 
may be pretty sure, therefore, that the land mammalia, snakes, and frogs now found 
wild have all been introduced. Of lizards, on the other hand, there are several spe- 
cies, some peculiar to the island, others common to Africa and the other Mascarene 
Islands. Tiie following list by Professor Dumeril is given in Maillard*s work: 

riaty dactyl us cepedianns. Ilemidactylns frenatus. 

*' ocellatus. Gongylus Bojerii. 

Ilemidactylns Peronii. Ablepharus Peronit 

** ' mutilatns. 

Four species of chameleon are now recorded from Bourbon and one from Mauri- 
tius (J. Reay Greene, M.D., in Popuiar Science Review^ April, 1880) ; but as they are 
not mentioned by the old writers, it is pretty certain that these creatures are recent 
introductions, and this is the more probable as they are favorite domestic pets. 



400 



ISLAND LIFE. 



2000 fatlioms; so tliat it is truly oceanic, like its larger sister- 
isles. 

Birds. — Tlie liviug birds of these islands arc few in nitinbsr, 
Aud cousigt mainly uf peculiar species of Mascureiic types, to- 
gether witli two peculiar genera — Oxynotus belonging to the 
Cnuipephngidte or caterpillar-catchers, a family abnnduut in the 
Old World tropics; aud a dove, Trocazza, forming a peculiar 
sub-geniie. The origin of these birds ofEers no difficulty, look- 
ing at the position of the islands and of the eurrounding shoals 
and islets. 

Jictinct Birtls. — These three islands are, however, pre-eini- 
nently remarkable as being tlie home of a group of large ground- 
birds, quite incapable of Hight, and altogether nnlike anything 
found elsewbero on the globe; and which, tJiough once very 
abundant, have become totally extinct within the last two hun- 
dred years. The best-known of these birds is the dodo, which 
inhabited Manritins; while allied species certainly lived in 
Bourbon and Kodrigiiez, abundant remains of the species of 
the latter island — the "solitaire" — -having been discovered, cor- 
responding with tho figure and description given of it by Le- 
guat, who i-esidcd in Rodriguez in ltil>2. These birds constitute 
a distinct family, Dididfe, allied to the pigeons, but very isolat- 
ed. They were quite helpless, and were rapidly exterminated 
when man introduced dogs, pigs, and cats into tlie islands, and 
himself sought them for food. The fact that such perfectly de- 
fenceless ereutiu'es survived in great abundance to a quite recent 
period in these three islands only, while there is no evidence of 
their ever having inhabited any other countries whatever, is it- 
self almost demonstrative that Mauritins, Bourbon, and Eodri- 
giiez are very ancient but truly oceanic islands. Fmm what we 
know of the general similarity of Miocene bii-ds to living genera 
aud f.iniilies, it seems clear that the origin of so remarkable a 
type as the dodos must date back to early Tertiary times. If we 
suppose some ancestral ground- feeding pigeon of large size to 
have reached the group by means of intervening islands after- 
wards submerged, and to have thenceforth remained to increase 
and multiply, unchecked by the attacks of any more powerful 
animals, we can well understand that the wings, being useless, 



Chap. XIX.] THE MADAGASCAR GKOUP. 401 

would in time become almost aborted.* It is also not improbable 
tliat this process would be aided by natural selection, because 
the use of wings might be absolutely prejudicial to the birds in 
their new home. Those that flew up into trees to roost, or tried 
to cross over the moutlis of rivers, might be blown out to sea 
and destroyed, especially during the hurricanes which have 
probably always more or less devastated the islands ; while, on 
the other hand, the more bulky and short-winged individuals, 
who took to sleeping on the ground in the forest, would be pre- 
served from such dangers, and perhaps also from the attacks of 
birds of prey which may always have visited the islands. But 
whether or not this was the mode by w^hich these singular birds 
acquired their actual form and structure, it is perfectly certain 
that their existence and development depended on complete iso- 
lation and on freedom from the attacks of enemies. We have 
no single example of such defenceless birds having ever existed 
on a continent at any geological period, whereas analogous though 
totally distinct forms do exist in New 2^aland, where enemies 
are equally wanting. On the other hand, every continent has 
always produced abundance of carnivora adapted to prey upon 
the herbivorous animals inhabiting it at the same period ; and 
we may therefore be sure that these islands have never formed 
part of a continent during any portion of the time when the 
dodos inhabited them. 

* That the dodo is really nn iibortioii from a more perfect ty|>o, and not n direct 
development from some lower form of wingless bird, is shown by its possessing a 
keeled sternum, though the keel is exceedingly reduced, being only three quarters 
of an inch dee]) in a length of seven inches. The most terrestrial pigeon — the Didnn- 
culus of the Sarooan Islands — has a far deeper and better-developed keel, showing 
that in the case of the dodo the degradation has been extreme. We have also anal- 
ogous examples in other extinct birds of the same group of islands, such as the flight- 
less rails, Aphanapteryx of Mauiitius and Erythromachus of Kodriguez, as well as 
the large parrot, Lopljopsittacas of Mauritius, and the night heron, Nycticorax me- 
(jnrtphala of Kodriguez, the last two birds probably having been able to fly a little. 
'J1ie commencement of the same process is to be seen in the peculiar dove of the Soy- 
cliclles, Turtur rostratus, which, as Mr. Edward Newton has shown, has much short- 
er wings than its close ally, T. picUtratus^ of ^fadagascar. For a full and interesting 
account of these and other extinct birds, see Professor Newton's article on ** Fossil 
Birds," in the Enr.ycloptvdia Britnnnica, 9th ed., Vol. III., p. 732, and that on 
** The Extinct Birds of liodriguez,*' by Dr. A. Giinther and Mr. E. Newton, in the 
Royal Societv's volume on the *• Transit of Venus Expedition." 

2G 



409 



ISLAND LIFE. 



[Paht ir. 



It is a remarkable thing that an ornithologist of Dr. Uart- 
laiib's reputation, looking at the subjoct from a purely ornitLo- 
logical point of view, should yet entirely ignore the evidence of 
these wonderful and unique bii-ds against hia own theory, when 
he 6o coniidently characterizes Lcmuria as "that sunken land 
which, containing parts of Africa, must have extended far east- 
ward over Southern India and Ceylon, and the highest points of 
which we recognize in the volcanic peaks of Bourbon and Mau- 
ritius, and in the eentral range of Madagascar itself — -the last re- 
sorts of the mostly extinct Lemurine race which formerly peo- 
pled it." ' It is here implied that lemurs formerly inhabited 
Bourbon and Mauritius, but of this there is not a particle of ev- 
idence ; and we feel pretty sure that had they done eo, the dodos 
would never have been developed there. In Madagascar there 
are no traces of dodos, while there are remains of extinct gigan- 
tic strnthious birds of the genus ^Epyornis, which were, no 
doubt, as well able to protect tiieiusclves against the smaller car- 
nivora as are the ostriches, cnms, and cassowaries in their re- 
spective countries at the present day. 

The whole of tlie evidence at onr command, therefore, tends 
toestablisli in avery complete manner the "oceanic "character of 
the three islands — ^Mauritius, Bourbon, and Bodriguez, and that 
they have never formed part of " Lemuria," or of any continent. 

JieptU'ea, — Mauritius, like Bourbon, has lizards, some of which 
are peculiar species; but no snakes, and no frogs or toads but 
such as have been introduced.* Strange to say, however, a email 
islet called Itound Island, only about a mile across, and situated 
about fourteen mih's northeast of Mauritius, possesses a snake 
which is not only unknown in Munritins, bnt also in any other 
part of the world, being altogether contiued to this minute islet 1 
It belongs to the Python fiintily, and forms a peculiar and very 
distinct genus, Casarca, whose nearest allies seem to be the Un- 
galia of Cuba and Bolgeria of Australia. It is hardly possible to 
believe that this ser|)ent has very long maintained itself on so 



!0 IbU, 1877. p. flM4. 



iiifurmcd by Dr. UUnl 



CuAP. XIX.] TUE MADAGASCAU GROUP. 403 

small an island ; and thongh we have no record of its existence 
on Mauritius, it may very well have inhabited the lowland for- 
ests without being met with by the early settlers ; and the intro- 
duction of swine, which soon ran wild and effected the final de- 
struction of the dodo, may also have been fatal to this snake. It 
is, however, now almost certainly confined to the one small islet, 
and is probably the land vertebrate of most restricted distribu- 
tion on the globe. 

<.)n the same island there is a small lizard, Thyinis Boyeri^ also 
a peculiar species and genus, but this is recorded from Mauritius 
and Bourbon as well, though it appears to be rare in both islands. 
As Round Island is connected with Mauritius by a bank under 
a hundred fathoms below the surface, it has probably been once 
joined to it, and when first separated would have been both 
much larger and much nearer the main island — circumstances 
which would greatly facilitate the transmission of these reptiles 
to their present dwelling-place. 

Flora of Madagascar and the Mascarene Idands. — The bot- 
any of the great island of Madagascar has been perhaps more 
thoroughly explored than that of the opposite coasts of Africa, 
so that its peculiarities may not be really so great as they now 
appear to be. Yet there can be no doubt of its extreme richness 
and grandeur, its remarkable speciality, and its anomalous exter- 
nal relations. It is characterized by a great abundance of forest 
trees and shinibs of peculiar genera or species, and often adorned 
with magnificent flowers. Some of these are allied to African 
forms, others to those of Asia, and it is said that of the two af- 
finities the latter preponderates. But there are also, as in the an- 
imal world, some decided South American relations, while others 
point to Australia, or are altogether isolated. 

Among the most prominent characteristics of the Madagascar 
flora is the possession of a peculiar and isolated family, Chlse- 
naceoe, allied somewhat to the balsams, but presenting very anom- 
alous characters. It consists of four genera and a number of spe- 
cies all entirely confined to the island. They are handsome trees 
or shrubs, mostly with showy red flowers. One of them, Rho- 
dolcEna altivola, is a semi-scandent shrub with magnificent cam- 
panulate flowei*s the size of a camellia, and of a brilliant purple 



404 



ISLAND LIFE. 



rPjutr n. 



color. Tlie genns Chrysopia consists of large forest trees with 
Bpreading crowns adorned with umbels or corymbs of lai^ pnr- 
ple flowers. It belongs to the Clusiaeea?, nnd is most nearly al- 
lied to tlie Soatb American genus Moronobea. Tbe Colvillea, a 
peculiar genus of Leguminosie, is a tree with splendid scarlet 
flowers; and there are a large number of other peculiar genera 
more or less remarkable. Combretacese with splendid flowers 
iibotind in l^ladagascar itself, though they arc rare in the Mss- 
oarene Islands ; while the Bavenala, or " travellers tree ;'' the ex- 
ti-aordinary lattiee-Icat-ed Ouvirandra; the Poitieianrt r-j^ia, oae 
of the most gorgeous of flowering trees; and the long-spurred 
Angraieitm. senquljiedaU, one of the most elegant and remarkable 
of orchids, are among its vegetable wondere." 

Of the flora of the smaller Madagasearian islands wo possess 
A much fuller account, owing to the recent publication of Mr. 
Baker's "Flora of the Mauritius and the Seychelles," including 
also ilodrigiiez. The tutal number of species in this flora is 1058, 
more than half of which (536) are exclusively Mascarenc — that 
i*, found only in some of the islands of the Madagascar group, 
while nearly a third (304) are ondemic or confined to single iel- 
ands. Of the wide-spread plants, fiO are found in Africa but 
not in Asia, and 86 in Asia but not in Africa, showing similar 
Asiatic preponderance to what is said to ticcnr in Madagascar. 
With tho genera, however, the proportions are different, for I 
find by going through the whole of the generic distributions as 
given by Mr. IJakcr, that out of tho 440 genera of wild plants 
50 are endeniio, 22 nro Asiatic but not African, while 28 arc 
African but not Asiatic. Tins implies that the more ancient 
connection has been on tho side of Africa, white a more recent 
immigration, shown by identity of species, has come from the 
side of Asia ; and it is probable tliat when the flora of Madagas- 
car is moro thoroughly worked out, the same or a still greater 
African prepomlepaneo will be found in that island. 

A few Mascarene genera arc found elsewhere only in South 
America, Anstmlia, or Polynesiii; and there are also a consid* 



' TIii> ikulcli of Ihn Horn of Mfldii^ii-cnr U tubrn cliioily ri-oni n ttriii of nrtldei 
l>v M. fiiiiilo Bli.iu'l.iirU. In iIjb Rtew ilt4 iJ^jr Jfn«./*j, V..I. CI, (1872). 



Chap.XIX] the MADAGASCAR GllOUP. 405 

crable number of genera whoso metropolis is South America, 
but which are represented by one or more species in Madagas- 
car, and by a single often widely distributed species in Africa. 
This fact throws light upon the problem oflfered by those mam- 
mals, reptiles, and insects of Madagascar which now have their 
only allies in South America, since the two cases would bo ex- 
actly parallel were the African plants to become extinct. Plants, 
however, are undoubtedly more long-lived specifically than ani- 
mals, especially the more highly organized groups, and are less 
liable to complete extinction through the attacks of enemies or 
through changes of climate or of physical geography ; hence we 
find comparatively few cases in which groups of Madagascar 
plants have their ordy allies in such distant regions as America 
and Australia, while such cases arc numerous among animals, 
owing to the extinction of the allied forms in intervening areas, 
for which extinction, as we have already shown, ample cause can 
be assigned. 

Curious Relations of Mascarene Plants. — Among the curious 
affinities of Mascarene plants we have culled the following from 
Mr. Baker's volume. Trochetia, a genus of Sterculiacese, has 
four species in Mauritius, one in Madagascar, and one in the 1x5- 
moto island of St. Ilelena. Mathurina, a genus of Turneraceip, 
consisting of a single species peculiar to liodriguez, has its near- 
est ally in another monotypic genus, Erblichia, confined to Cen- 
tral America. Siegesbeckia, one of the Compositae, consists of 
two species, one inhabiting the Mascarene Islands, the other 
Peru. Labourdonasia, a genus of Sapotaceffi, has two species in 
Mauritius, one in Natal, and one in Cuba. Nesogenes, belonging 
to the verbena family, has one species in Rodriguez and one in 
Polynesia. Mespilodaphne, an extensive genus of I^uraccffi, has 
six species in the Mascarene Islands, and all the rest (about fifty 
species) in South America. Nepenthes, the well-known pitcher- 
plants, are found chiefly in the Malay Islands, South China, and 
Ceylon, with species in the Seychelle Islands and in Madagascar. 
Milla,a large genus of Liliaceae, is exclusively American, except 
one species found in Mauritius and Bourbon. Agauria, a genus 
of Ericaceae, is confined to the Mascarene Islands and the Cama- 
roon Mountains in West Africa. An acacia found in Mauritius 



406 ISLAND LIFE. [Part II. 

and Bourbon {A, heterophylla) can hardly be separated specif- 
ically from Acacia hoa of the Sandwich Islands. The genus 
Pandanus, or screw-pine, has sixteen species in the three islands 
— ^Mauritius, Rodriguez, and the Seychelles — all being peculiar, 
and none ranging beyond a single island. Of palms there are 
fifteen species belonging to ten genera, and all these genera are 
peculiar to the islands. We have here ample evidence that 
plants exhibit the same anomalies of distribution in these islands 
as do the animals, though in a smaller proportion ; while they 
also exhibit some of the transitional stages by which these anom- 
alies have, in all probability, been brought about, rendering quite 
unnecessary any other changes in the distribution of sea and land 
than physical and geological evidence warrants.* 



* It mny be interesting to botanists and to students of geograpliical distribution to 
give here an enumeration of the endemic genera of the ** Flora of the Mauritius and 
the Seychelles/' as they are nowhere separately tabulated in that work. 

Aphloia (Bixaceo:) 1 sp., a shrub, Mauritius, Kodriguez, Seychelles, also 

Madagascar. 

Medusagyne (Ternstromiacete). 1 sp., a shrub, Seychelles. 

Astiria (Sterculiaceie) 1 sp., a shrub, Mauritius. 

Qnivisia (Meliaceae) 3 sp., shrubs, Mauritius (2 sp.), Rodriguez (I sp.), 

also Bourbon. 

Cossignya (Sapindnceac) 1 sp., a shrub, Mauritius, also Bourbon. 

Hornea ** 1 sp., a shrub, Mauritius. 

Stadtmannia ** 1 sp., a shrub, Mauritius. 

Doratoxylon ** 1 sp., a shrub, Mauritius and Bourbon. 

Gngnebina (Leguminosic) 1 sp., a shrub, Mauritius, also Madagascar. 

Roussea (Saxitragacea;) 1 sp., a climbing shrub, Mauritius and Bourbon. 

Tetrataxis (Lythraceai) 1 sp., a shrub, Mauritius. 

Psiloxylon ** 1 sp., a shrub, Mauritius and Bourbon. 

MathuVina (Tumeracea;) 1 sp., a shrub, Rodriguez. 

Faetidia (Myrtaccffi) 1 sp., a tree, Mauritius. 

Dnnais (liubiacca?) 4 sp., climbing shrubs, Mauritius (I sp.), Rodriguez 

(I sp,), also Bourbon and Madagascar. 

Fernelia '* 1 sp., a slnub, Mauritius and Rodriguez. 

I'yrostria " 6 sp., shrubs, Mauritius (3 sp.), also Bourbon and 

Madagascar. 

Scyphochlamys '* 1 sp., a shrub, Rodriguez. 

Myonima ** Jl sp., shrubs, Mauritius, also Bourbon. 

Cylindroclino (Composita?) 1 sp., a shrub, Mauritius. 

Monarrhenus *' 2 sp., shrubs, Mauritius, also Bourbon and Mada- 

gascar. 

Fanjasia ** 3 sp., shrubs, Mauritius, also Bourbon and Mada- 

gascar. 

Iletcrochaenia (Campanulacca*). 1 sp., a shrub, Mauritius, also Bourbon. 

Tauulepi? (Asclepiadacexc) 1 sp., a climber, Rodriguez. 

Decaucma ** 1 sp., a climber, Mauritius, also Madagascar. 



Chap. XIX.] THE MADAGASCAR GllOUP. 407 

Fragmentary Character of the Mascarene Flora, — Al though 
the peculiar character and affinities of the vegetation of these 
islands are sufficiently apparent, there can be little doubt that we 
only possess a fragment of the rich flora which once adorned 
them. The cultivation of sugar and other tropical products has 
led to the clearing-away of the virgin forests from all the low- 
lands, plateaus, and accessible slopes of the mountains, so that 
remains of the aboriginal woodlands only linger in the recesses 
of the hills, and numbers of forest-haunting plants must inevi- 
tably have been exterminated. The result is that nearly three 
hundred species of foreign plants have run wild in Mauritius, 
and have in their turn helped to extinguish the native species. 



Nicodemia (Lognnincete) 2 sp., shrubs, Mnurititis (1 sp.), also Comoro Islands 

niid Madagascar. 

Bryodes (Serophulariaceje) 1 sp., herb, Mauritius. 

liadamaca *^ 2 sp., herb, Seychelles (1 sp.) and Madagascar. 

Colea (Rignoniaceae) 10 sp., Mauritius (I sp.), Seychelles (1 sp.), also 

Bourbon and Madagascar. (Shrubs, trees, or 
climbers.) 

Obetia (Crticaces) - sp* shrubs, Mauritius, Seychelles, and Madagascar. 

Bosquiea (Moreae) 3 sp., trees, Seychelles (1 sp.), also Madagascar. 

Monimia (Moniminceae) 3 sp., trees, Mauritius (2 sp.), also Bourbon. 

Cynorchis (Orchideie) 3 sp., herb, ter., Mauritius. 

Amphorchis '^ 1 sp** herb, ter., Mauritius, also Bourbon. 

Amottia ** 2 sp., herb, ter., Mauritius, also Bourbon. 

Aplostellis ** 1 sp., herb, ter., Mauritius. 

Cryptopiis ** 1 sp., herb, Epiphyte, Mauritius, also Bourbon and 

Madagascar. 

Lomatophvllum (Liliaceie) 3 sp., shrubs (succulent), Mauritius, also Bourbon. 

Lodoicca (Palma;) 1 sp., tree, Seychelles. 

Latauia '* 3 sp., trees, Mauritius (2 sp.), Rodriguez, also Bour- 

bon. 

Hyophorbe ** 3 sp., trees, Mauritius (2 sp.), Rodriguez, also Bour- 

bon. 

Dictyosperma ** 1 ^Pm ^r^^t Mauritins, Rodriguez, also Bourbon. 

Acantiiophoenix ** - sp., trees, Mauritius, also Bourbon. 

Deckenia ** 1 «*?•» tree, Seychelles. 

Ncphrosperma ** 1 sp., tree, Seychelles. 

lioscheria *' 1 8P-> tree, Seychelles. 

Verschaffeltia ** 1 ^Pm tree, Seychelles. 

Sfevensonia ** 1 ^Pm tree, Seychelles. 

Ocliropieris (Filices) 1 pp., herb, Mauritius, also Bourbon and Madagas- 
car. 

Among the curious features in this list are the great number of endemic shrubs in 
Mauritius, and the remarkable assemblage of five endemic genera of palms in tlie 
Seychelle Islands. We may also notice that one palm {Latania Loddigesti) is con- 
fined to Round Island and two other adjacent islets, offering a singular analogy Co 
the peculiar snake also found there. 



ISLAND LIFE. 



[PiMU. 



In the Sej'cbellea, too, the indigenous flora has hecn almost en- 
tirely (leetroyed in most of tlie ielaiicis, although tlie peculiar 
palms, from their longevity and comparative hardiness, have 
survived. Mr. Geoifrey Nevill tells na that nt Mahe and most 
of the other islands visited by liim, it was only in a few spots 
near the summits of the hills that he could perceive any remains 
of the ancient fiora. Pineapples, cinnamon, bamboos, and other 
plants have obtained a firm footing, covering large tracts of 
country, and killing the more delicate native tlowei's and ferns. 
The pineapple, especially, grows almost to tlio tops of the 
moantaioB. Where the timber and shrubs have been destroyed, 
the water falling on the surface immediately cuts channels, rune 
off rapidly, and caueee the land to become dry and arid ; and the 
same effect is largely seen both in Mauritius and Bourbon, 
where, originally, dense forest covered the entire surface, and 
perennial moisture, with its ever-accompanying luxuriance of 
vegetation, prevailed. 

Flora of Madagascar Allied to that of South Africa. — In my 
" Geognipliieal Distribution of Animals," I have rcmarlied on 
the relation between the insects of Madagascar and those of 
south temperate Africa, aud have speculated on a great aouthern 
extension of the continent at the time when Madagascar was 
united with it. As supporting this view I now quote Mr. Hent- 
ham's remarks on the Compositte. He eays, "The connections 
of the Mascarene endemic Compositie, especially those of Mada- 
gascar itself, are eminently with the southern and subtropical 
African races ; the more tropical races, Plucheineee, etc., may be 
rather more of an Asiatic type." lie further says that the Com- 
posite flora is almost as strictly endemic as that of the Sandwich 
Islands, and that it is much diversified, with evidences of great 
antiquity, while it shows insular characteristics in the tendency 
to tall shrubby or arborescent forma in several of the endemic or 
prevailing genera. 

PrejHmderaiic^ of Ferns in the Ma%carenc Flora. — A striking 
character of the flora of these smaller Mascarene islands is the 
great preponderance of ferns, and next to tliem of Oi-chideje, 
The following figures arc taken from Mr. Baker's "Flora" for 
Mauritius and the Seychelles, and from an estimate by M. Frap- 



CiiAP.XIX.] THE MADAGASCAR GROUP. 409 

pier of the flom of Bourbon given in Maillard's volume already 
quoted : 

Mauritius, etc. Bom bon. 

Ferns 1G8 1 Ferns 240 

Orchideo; 71) Orchideas 120 



Gramineic CO 

CyperaceiB G2 

Rabiacexc r>7 



Gramineie GO 

Composita; GO 

Jjeguminosa} 30 



Eaphorbiacea: 4.'i i Rubiaccxe 24 

Composita;. 43 Cyperaceae 24 

Leguminosae 41 1 Euphorbiaceoe. 18 

The cause of the great preponderance of ferns in oceanic isl- 
ands has already been discussed in my book on " Tropical Nat- 
ure ;" and we have seen that Mauritius, Bourbon, and Rodri- 
guez must be classed as such, though from their proximity to 
Madagascar they have to be considered as satellites to that great 
island. The abundance of orchids may be in part due to analo- 
gous causes. Their usually minute and abundant seeds would 
be as easily carried by the wind as the spores of ferns, and their 
frequent epiphytic habit affords them an endless variety of sta- 
tions on which to vegetate, and at the same time removes them, 
in a great measure, from the competition of other plants. When, 
therefore, the climate is sufficiently moist and equable, and there 
is a luxuriant forest vegetation, we may expect to find orchids 
abundant on such tropical islands as are not too far removed 
from other lands or continents from which their seeds might be 
conveyed. 

Concluding Remarks on Madagascar and the Mascarene Isl- 
ands, — There is probably no portion of the globe that contains 
wfthin itself so many and such varied features of interest con- 
nected with geographical distribution, or which so well illus- 
trates the mode of solving the problems it presents, as the com- 
paratively small insular region which comprises the great island 
of Madagascar and the smaller islands and island-grOups which 
immediately surround it. In Madagascar we have a continental 
island of the first rank, and undoubtedly of immense antiquity; 
we have detached fragments of this island in the Comoros and 
Aldabra ; in the Seychelles we have the fragments of another 
very ancient island, which may perhaps never have been conti- 



410 



ISLAND LIFE. 



[Pm 



[lental ; in Muuritiiis, Eoiirbon, and Rodriguez we have three 
iiiidonbtediy oceanic islands ; while in tlie extensive banks and 
eoral reefs of Cargados, Saya de Maiha, the Chagos, and the Mal- 
dive Isles we have indications of the submergence of many large 
islands which may have aided in the transmission of organisms 
from the Indian Peninsula. But between and around all these 
islands we liave depths of 25LH> fathoms and upwards, which 
renders it very improbable that there has ever been here a con- 
tinuous land surface, at all events during the Tertiary or Sec- 
ondary period of geolon:y. 

It is most interesting and satisfactory to find that this conclu- 
sion, arrived at solely by a study of the form of the sea-bottom 
and the general principle of oceanic permanence, is fully snp- 
ported by tie evidence of the organic productions of the several 
islands; because it gives us contidenee in those principles, and 
helps to supply us with a practical demonstration of them. We 
find that the entire group contains just that amount of Indian 
forms wliicli could well have passed from island to island ; that 
many of these forms are slightly modified species, indicating 
that the migration occurred during late Tertiary times; while 
others are distinct genera, indicating a more ancient connection. 
Bat in no one case do we fiud animaU which necessitate an actual 
land-connection ; while the numerous Indian types of mammalia, 
reptiles, birds, and insects, which must certainly have passed over 
had there been sncli an actual land-connection, are totally want- 
ing. The one fact which has been supposed to require such a 
connection — the distribution of the lemurs^ — can be far more 
naturally explained by a general dispersion of the group from 
Europe, where we know it existed in Eocene times; and such 
an explanation applies equally to the affinity of the Insectivora 
of Madagascar and Cuba, the snakes (I lerpetodryas, etc.) of 
Madagascar and America, and the lizards (Cryptoblepharns) of 
Manritius and Australia, To suppose, in all these cases, and in 
many others, a dii-ect land-connection is really abenrd, because 
we havo the evidence afforded by geology of wide differences 
of distribution directly wn pass lieyond the most recent deposits; 
and when wo go back to Mesozoic, and still more to Palfeozoic, 
times, the majority of the groups of animals and plants appear 



Chap. XIX.] THE MADAGASCAR GROUP. 411 

to have liad a world-wide range. A large number of our Euro- 
pean Miocene genera of vertebrates were also Indian or African, 
or even American ; the South American Tertiary fauna con- 
tained many European types ; while many Mesozoic reptiles and 
mollusca ranged from Europe and North America to Australia 
and New Zealand. 

By direct proof (the occurrence of wide areas of marine de- 
posits of Eocene age), geologists have established the fact that 
Africa was cut off from Europe and Asia by an arm of the sea 
in early Tertiary times, forming a large island-continent. By 
the evidence of abundant organic remains we know that all the 
types of large mammalia now found in Africa (but which are 
absent from Madagascar) inhabited Europe and Asia, and many 
of them also North America, in the Miocene period. At a still 
earlier epoch Africa may have received its lower types of mam- 
mals — lemurs, insectivora, and small carnivora, together with 
its ancestral struthious birds, and its reptiles and insects of 
American or Australian affinity ; and at this period it was joined 
to Madagascar. Before the later continental period of Africa, 
Madagascar had become an island ; and thus, when the large 
mammalia from the northern continent overran Africa, they 
were prevented from reaching Madagascar, which thenceforth 
was enabled to develop its singular forms of low-type mamma- 
lia, its gigantic ostrich-like j^lpyornis, its isolated birds, its re- 
markable insects, and its rich and peculiar flora. From it the 
adjacent islands received such organisms as could cross the sea; 
while they transmitted to Madagascar some of the Indian birds 
and insects which had reached them. 

The method we have followed in these investigations is to ac- 
cept the results of geological and palseontological science, and 
the ascertained facts as to the powere of dispereal of the various 
animal groups ; to take full account of the laws of evolution as 
affecting distribution, and of the various ocean depths as imply- 
ing recent or remote union of islands with their adjacent conti- 
nents ; and the result is that wherever we possess a sufficient 
knowledge of these various classes of evidence, we find it possi- 
ble to give a connected and intelligible explanation of all the 
most striking peculiarities of the organic world. In Madagas- 



112 



ISLAND LIFE. 



CPJOT It 



oar we liave iiiKlovibtedly one of tlie most difficult of these prob- 
lems; but we have, I tliink, fnirlj met and conquered most of 
its difficulties. The coini)le.xUj of the organic relations of this 
igland is due jwirtly to its having derived its animal forms from 
two distinct sources — from one continent throngh a direct land- 
connection, and from another by ine.ana of intervening islands 
now eulimerged ; but mainly to the fact of its having been BCp- 
arated from a continent which is now, zoologically, in a very dif- 
ferent condition from what it was at the time of the separation ; 
and to its having been thus able to preserve a number of types 
which may date back to the Eocene, or even to the Ci'etaceous, 
period. Sonic of ihcse types liavo become altogether extinct 
elsewhere ; others have spread far and wide over the globe, and 
have survived only in a few remoto countries, and especially in 
those which have been more or less secured by their isolated po- 
sition from the incursions of the more highly developed forms 
of later times. This explains why it is that the nearest allies 
of the Madagascar fauna and flora are now so often to be found 
in South America or Australia — countries in which low forms 
of mammalia and birds still largely prevail — it being on account 
iif the long-continued isolation of all these countries that simi- 
lar forms (descendants of ancient types) are preserved in tliem. 
Had the numerous suggested continental extensions connecting 
these remote continents nt various geological periods been resli- 
ties, the result wonld havo been that all these interesting archaic 
forms, all these helpless insular types, would long ago have been 
exterminated, and one comparatively monotonous fauna have 
reigned over the whole earth. So far from explaining the anom- 
alous facts, the alleged continental extensions, had they existed, 
would have left no such fiicfs to be explained. 



i 



Chap. XX.] CELEBES. 413 



CHAPTER XX. 

ANOMALOUS ISLANDS: CELEBES. 

Anomalous Relations of Celebes. — Physical Featnres of the Island. — Zoological 
Character of the Islands around Celebes. — The lilalnvan and Australian Banks. — 
Zoology of Celebes: Mararaalia. — Probable Derivation of the Mammals of Cele- 
bes. — Birds of Celebes. — Bird-types Peculiar to Celebes. — ^Celebes not strictly a 
Continental Island. — Peculiarities of the Insects of Celebes. — Himalayan Types 
of Birds and Butterflies in Celebes. — Peculiarities of Shape and Color of Celebe- 
sian Butterflies. — Concluding Bemarks. — Appendix on the Birds of Celebes. 

The only other islands of the globe which can be classed as 
"ancient continental" are the larger Antilles (Cuba, Hayti, Ja- 
maica, and Porto Kico), Iceland, and perhaps Celebes. Tlie An- 
tilles have been so fully discussed and illustrated iu my former 
work, and there is so little fresh information about them, that 
I do not propose to treat of them here, especially as they fall 
short of Madagascar in all points of biological interest, and offer 
no problems of a different character from such as have already 
been sufficiently explained. 

Iceland, also, must apparently be classed as belonging to the 
"Ancient Continental Islands," for though usually described as 
wholly volcanic, it is more probably an island of varied geolog- 
ical structure buried under the lavas of its numerous volcanoes. 
But of late years extensive Tertiary deposits of Miocene age 
have been discovered, showing that it is not a mere congeries 
of volcanoes ; it is connected with the British Islands and with 
Greenland by seas less than 500 fathoms deep; and it possesses 
a few mammalia, one of which is peculiar, and at least three pe- 
culiar species of birds. It was therefore almost certainly united 
with Greenland, and probably with Europe by way of Britain, 
in the early part of the Tertiary period, and thus afforded one 
of the routes by which that intermigration of American and 
European animals and plants was effected which we know oc- 



414: ISLAND LIFE. [Part IL 

cuiTed during some portion of the Eocene and Miocene periods, 
and probably also in the Pliocene. The fauna and flora 'of this 
island are, however, so poor, and offer so few peculiarities, that 
it is unnecessary to devote more time to their consideration here. 

There remains the great Malay island Celebes, which, owing 
to its possession of several large and very peculiar mammalia, 
must be classed, zoologically, as "ancient continental," but 
whose central position and relations both to Asia and to Aus- 
tralia render it very difficult to decide in which of the primary 
zoological regions it ought to be placed, or whether it has ever 
been united with either of the great continents. Although I 
have pretty fully discussed its zoological peculiarities and past 
history in my " Geographical Distribution of Animals," it seems 
advisable to review the facts on the present occasion, more es- 
pecially as the systematic investigation of the characteristics of 
continental islands we have now made will place us in a better 
position for determining its true zoo-geographical relations. 

Physical Features of Cehhes, — This large and still compara- 
tively unexplored island is interesting to the geographer on ac- 
count of its remarkable form, but much more so to the zoologist 
for its curious assemblage of animal forms. The geological 
structure of Celebes is almost unknown. The extremity of the 
northern peninsula is volcanic; while in the southern peninsula 
there are extensive deposits of a crystalline limestone, in some 
places overlying basalt. Gold is found in the northern penin- 
sula and in the central mass, as well as iron, tin, and co])per in 
small quantities ; so that there can be little doubt that the moun- 
tain-ranges of the interior consist of ancient stratifted rocks. 

It is not yet known whether Celebes is completely separated 
from the surrounding ijjlands by a deep sea, but the facts at our 
command render it probable that it is so. The northern and 
eastern portions of the Celebes Sea have been ascertained to be 
from 2000 to 2(500 fathoms deep, and such depths ma}^ extend 
over a considerable portion of it, or even be much exceeded in 
the centre. In the Molucca passage a single sounding on the 
Gilolo side gave 1200 fathoms, and a large part of the ilolucca 
and Baiula Seas probably exceeds 2000 fathoms. The southern 
portion of the Strait of ^lacassar is full of coral reefs, and a 



Cmr. XX.] 



CELEBES. 



415 



bIiiiIIow Bea of less than 100 fatlioins extends from Borneo to 
within about furtj miles of tlic western promontory of Celebes ; 
but further iiortii there is deej) water close to the sliore, iind it 




Tlia depth ofKU iiahown by ihree tinia; tlie ll];lil«9[ iiiitienlitig IcM ihnn 100 Tiitli. 
iiin«. tlie BiFilium iiii( lets ilmn lOOtl fuilioniR, aiiJ tlie tlortL tiul more tlinii JOUO 
laiLoms. Tlie ligurea iboiv depth* iu fiulioms, 

soems probable that a deep channel extends quite through the 
strait, which has, no doubt, been miidi shallowed hy the dcpoails 
from the great Bornean rivers as well as by t\yose of Celebes 
itself. Southward again, tlie chain of volcanic islands from Bali 



416 



ISLAND UFE. 



[P*« W. 



to Timor appear to rise out of a deep ocean, the few Eoundings 
wo possess showing depths of from 670 to 1300 fathonia almost 
close to their northern shores. We seem justified, therefore, in 
concluding that Celebes is entirety surrounded hy a deep sea, 
which has, however, become partially filled np by river deposits, 
by volcanic upheaval, or by coral reefs. Such shallows, whei-c 
they exist, may thei-efore he due to antiquity and isolation, in- 
Etead of being indications of a former union with any of the 
surrounding i&lnnds. 

Zoolof/ical Character of the fffamh around Cdeheg. — In oi-der 
to have & clear conception of the peculiar character of the Cele- 
bcsian fauna, we must take into account that of the surrounding 
countries from which we may suppose it to liave received ini- 
migrants. Tliese we may divide broadly into two groups, those 
on tlie west belonging to the Oriental region of our zoological 
geography, and those on the east belonging to the Australian 
region. Of the first group Borneo is a typical repi-esentativo; 
and from its proximity and the extent of its opposing coasts it 
is the island wliich we should expect to show most resemblance 
to Celebes. We have already seen that the fauna of Borneo is 
essentially the same as that of Southern Asia, and that it is ex- 
cessively rich in all the Malayiin types of mammalia and birds. 
Java and Bali closely i-escmble Borneo in general character, 
though somewhat less rich and with several peculiar forms; 
while the Philippine Islands, though very much poorer, and 
Avitb n greater amount of speciality, yet exhibit essentiftl!y the 
same character. These islands, taken as a whole, may be de- 
scribed as having a fauna almost identical with that of Southern 
Asia; for no family of mammalia is found in llie one which is 
absent from the other, and the same may be said, with very few 
and unimportant exceptions, of the birds; while hundreds of 
genera and of species are common to both. 

In the islnnds east and south of Celebes — the MoluccjiSj New 
Oninoa, and the Timor group from Lonibok eastward — we find, 
on the other hand, the most wonderful contrast in the forms of 
life. Of twenty-seven families of terrestrial mammals found in 
the great Malay islands, all have disappeared but fonr, and of 
these it is doubtfnl whether two have not been introduced by 



Chap. XX.J CELEBES. 417 

man. We also find here four families of Marsupials, all totally 
unknown in the western islands. Even birds, though usually 
more widely spread, show a corresponding difference, about 
eleven Malayan families being quite unknown east of Celebes, 
where six new families make their appearance which are equally 
unknown to the westward.' 

We have here a radical difference between two sets of islands 
not very far removed from each other, the one set belonging 
zoologically to Asia, the other to Australia. The Asiatic or 
Malayan group is found to be bounded strictly by the eastward 
limits of the great bank (for the most part less than fifty fath- 
oms below the surface) which stretches out from the Siamese 
and Malayan peninsulas as far as Java, Sumatra, Borneo, and 
the Philippines. To the east another bank unites New Guinea 
and the Papuan Islands as far as Aru, Mysol, and Waigiou, with 
Australia; while the Molucca and Timor groups are surrounded 
by much deeper water, which forms, in the Banda and Celebes 
seas, and perhaps in other parts of this area, great basins of 
enormous depths (2000 to 3000 fathoms, or even more) en- 
closed by tracts under 1000 fathoms, which separate the basins 
from each other and from the adjacent Pacific and Indian 
oceans (see map). This peculiar formation of the sea-bottom 
probably indicates that this area has been the seat of great local 
upheavals and subsidences; and it is quite in accordance with 
this view that we find the Moluccas, while closely agreeing with 
New Guinea in their forms of life, yet strikingly deficient in 



' Families of Malayan Birds not Found 
in Islands East of Celebes. 

Troglodytidse. 

Sittidae. 

Pandas. 

Liotrichidse. 

PbjUornithidie. 

EurylsemidiB. 

Picidffi. 

Indicatoridn. 

Megalieroidfle. 

Trogonidie. 

Phasianidie. 



Families of Moluccan Birds not Fonnd 
in Islands West of Celebes. 

ParadiseidsB. 

Meliphagidje. 

CacatuidsB. 

Platycercidae. 

Trichoglossidxe. 

Nestoiidie. 



27 



418 



ISLAND LlFi:. 



rll. 



many important groups, and exhibiting an altogetlier poverty- 
stricken appearance as regards tlie liigher animals. It is » sug- 
gestive fact that the Philippine Ishinds bear a» exactly parallel 
ixjlation to Borneo, being equally deficient in many of the higher 
groups; and hero too, in the Sooloo Sea, we find a similar en- 
closed basin of great depth. Hence wo may in both cases con- 
nect, on the one hand, tlie extensive area of land surface and of 
adjacent slitillow sea with a long period of stability and a con- 
sequent I'icb development of the forms of life; and, on the 
other hand, a highly broken land surface, with the adjacent seas 
of gre.1t but very unequal depths, with a period of disturbance, 
probably involving extensive Bubniersions of the land, resulting 
in a scanty and fragmentary vertebrate fauna. 

Zoolofjij of Cdfhes. — The zoology of Celebes differs so remark- 
ably from that of both the great divisions of the archipelago 
above indicated that it is very diflSenlt to decide in which to 
place it. It possesses only about sixteen species of terrestrial 
niauimalia,so tliat it is at once distinguished from Borneo and 
Java by its extreme poverty in this class. Of this small number 
fonr belong to the Molncean and Australian fauna — there being 
two marsnpiuls of the genus Cnsctis, and two forest rats said to 
bo allied to Australian types. 

The remaining twelve species are, generally speaking, of Ma- 
layan or Asiatic types, but some of them arc so peculiar that 
they have no near allies in any part of the woild ; while the 
rest are of the ordinary Malay type, or even identical with Ma- 
layan species, and some of these may be recent introductions 
through Iniinan agency. These twelve apecies of Asiatic typo 
will be now enumerated. They eoueist of five peculiar squirrels 
— a group imknown farther east; a peculiar species of wild-pig; 
ft deer bo closely allied to the Cervua /n'jipehp/ius of IJomeo 
that it may well have been introduced by man both here and in 
the Moluccas; a civet, Viivrra tangalnnija, common in all the 
Malay islands, and also perhaps introduced ; the curious Malayan 
tarsier{7rtraiw**^jet'//'um),said to bo only found in a small island 
oS the coast ; and, besides these, three remarkable animals, all of 
large size, and all qnite unlike anything found in the Malay Isl- 
ands or even in Asia. These arc a black and almost tailless 



Chap. XX.] CELEBES. 419 

baboon-like ape (Oj/nopit/iecus nigrescens); an antelopean buf- 
falo {Anoa depr€88icomu\ and the strange babirusa {Babirusa 
alfurus). 

None of these three animals last mentioned have any close 
allies elsewhere, and their presence in Celebes may be considered 
the crucial fact which must give us the clew to the past history 
of the island. Let us, then, see what they teach us. The ape 
is apparently somewhat intermediate betw^een the great baboons 
of Africa and the short-tailed macaques of Asia, but its ci*anium 
shows a nearer approach to the former group in its flat project- 
ing muzzle, large superciliary crests, and maxillary ridges. The 
anoa, though anatomically allied to the buffaloes, externally 
more resembles the bovine antelopes of Africa; while the 
babirusa is altogether unlike any other living member of the 
swine family, the canines of the upper jaws growing directly 
upward like horns, forming a spiral curve over the eyes, instead 
of downward, as in all other mammalia. An approach to this 
peculiarity is made by the African wart-hogs, in which the upper 
tusk grows out laterally and then curves up ; but these animals 
are not otherwise closely allied to the babirusa. 

ProbahU Derivation of the Mammals of Celebes. — It is clear 
that we have here a group of extremely peculiar, and in all 
probability very ancient, forms, which have been preserved to 
us by isolation in Celebes, just Jis the monotremes and mar- 
supials have been preserved in Australia, and so many of the 
lemurs and Insectivora in Madagascar. And this compels us 
to look upon the existing island as a fragment of some ancient 
land, once perhaps forming part of the great northern continent, 
but separated from it far earlier than Borneo, Sumatra, and Java. 
The exceeding scantiness of the mammalian fauna, however, re- 
mains to be accounted for. We have seen that Formosa, a much 
smaller island, contains more than twice as many species ; and 
we may be sure that at the time when such animals as apes 
and buffaloes existed, the Asiatic continent swarmed with varied 
forms of mammals to quite as great an extent as Borneo does 
now. If the portion of separated land had been anything like 
as large as Celebes now is, it would certainly have preserved a 
far more abundant and varied fauna. To explain the facts we 



420 



ISLAND LIFE. 



[P*nr n. 



have the choice of two theories — either that the origiual island 
has since its scparatiou been gieatly reduced by snbiuersion, eo 
as to lead to the extinction of most of the higher land animals; 
or that it originally formed part of an independent land stretch- 
ing eastward, and was only united with the Asiatic continent 
for a short period, or perhaps even never united at all, but so 
connected by intervening islands separated by narrow straits 
that a few mammals might find tlieir way across. The latter 
supposition apjtears best to explain the facts. The three animals 
in question are such as might readily pass over narrow straits 
from island to island ; and we are thus better enabled to under- 
stand the complete absence of the arboreal monkeys, of the In- 
Bcctivora, and of tlie very numerous and varied Carnivora and 
llodents of Borneo, all of which are entirely uii represented in 
Celebes by any peculiar and ancient forms except the squirrels. 
The question at issue can only be finally determined by geo- 
logical iuvosligations. If Celebes has once formed part of Asia, 
and participated in its rich mammalian fauna which has been 
since destroyed by submergence, then some remains of this fauna 
must certainly be preserved in caves or late Tei'tiary deposits, 
and proofs of the submergence itself will be found when sought 
for. If, on the other hand, the existing animals fairly represent 
those which bare ever reached the island, then no sueb remains 
will bo discovered, and there need bo no evidence of any great 
and extensive subsidence in late Tertiary times. 

Birth of Cdehes. — Having thus clearly placed before us the 
problem presented by the mammalian fauna of Celebes, we may 
proceed to see what additional evidence is afforded by the birds, 
and any other groups of which we have sufficient information. 
About 164 species of true land birds are now known to inhabit 
tlie island of Celebes itself. Considerably more than half of 
these (94 species) are peculiar to it ; 29 ai-o found also in Borneo 
and the other Malay islands, to which thoy specially belong; 
while IG are common to the Moluccas or other islands of the 
Australian region ; the remainder being species of wide range, 
and not characteristic of either division of the archipelago. We 
have here a large prepontlerance of Western over Eastern species 
of birds inhabiting Celebes, though not to qnite so great an ex- 



CiiAF. XX.] CELEBES. 421 

tent as in the mammalia; and the inference to be drawn from 
tills fact is, simply, that more birds have migrated from Borneo 
than from the Moluccas — which is exactly what wo might ex- 
pect, both from tlie gi'eater extent of the coast of Borneo oppo- 
site that of Celebes, and also from the much greater richness in 
species of the Bornean than the Moluccan bird fauna. 

It is, however, to the relations of the peculiar species of Cele- 
besian birds that we must turn in order to ascertain the origin 
of the fauna in past times ; and we must look to the source of 
the generic types which they represent to give us this informa- 
tion. The ninety-four peculiar species above noted belong to 
about sixty-six genera, of which about twenty-three are common 
to the whole archipelago, and have therefore little significance. 
Of the remainder, twelve are altogether peculiar to Celebes ; 
twenty-one are Malayan, but not Moluccan or Australian ; while 
ten are Moluccan or Australian, but not Malayan. This propor- 
tion does not differ much from that afforded by the non-peculiar 
species ; and it teaches us that, for a considerable period, Cele- 
bes has been receiving immigrants from all sides, many of which 
have had time to become modified into distinct representative 
species. These evidently belong to the period during which 
Borneo, on the one side, and the Moluccas, on the other, have oc- 
cupied very much the same relative position as now. There re- 
main the twelve peculiar Celebesian genei-a, to which we must 
look for some further clew as to the origin of the older portion 
of the fauna ; and as these are especially interesting, we must 
examine them somewhat closely. 

Bird-types Peculiar to Celebes, — First we have Artamides, 
one of the Campephagina?, or caterpillar -shrikes — a not very 
well-marked genus, and which may have been derived either 
from the Malayan or the Moluccan side of the archipelago. 
Two peculiar genera of kingfishers — Monachalcyon and Cittura 
— seem allied, the former to the wide-spread Todiramphus and 
to the Caridonax of Lombok, the latter to the Australian Meli- 
dora. Another kingfisher, Ceycopsis, combines the characters 
of the Malayan Ceyx and the African Ispidina, and thus forms 
an example of an ancient generalized form analogous to what 
occurs among the mammalia. Streptocitta is a peculiar form 



422 



ISLAND LIFE. 



[Vktn II. 



allied to the magpies ; wliilc Basilornis {found also in Ceram), 
EnodeE, and Sciesirostrum are very peculiar starlings, the latter 
altogether unlike any other bird, and perhaps forming a diBtinet 
8ub-familj-. Meropogon is a peculiar bee-eater, allied to the 
Malayau Nyctiornis ; Rhamphocoecyx is a modification of PhiB- 
iiicophaes, a Maiayau genus of cuckoos ; Prioniturus (found also 
in the Philippines) is a genus of parrots distinguished by raquet- 
formed tail-feathers, attogetlier unique in the order; while Mega- 
cephalon is a remarkable and very isolated form of the Aus- 
ti-alian Megapodiida?, or mound-builders. 

Omitting those whose affinity may be pretty clearly traced to 
groups still inhabiting the islands of the western or the eastern 
half of the archipelago, wo find four birds which have no near 
allies at all, but appear to be cither ancestral forms, or extreme 
modifications, of Asiatic or African birds — Basilornis, Euodes, 
Scissi rostrum, Ceycopsis, Tlieso may fairly be associated wi(h 
the baboon-ape, auoa, and Imbirusa, ns indicating extreme antiq- 
uity and some communication with the Asiatic continent at a 
period when the forms of life and their geographical distribu- 
tion differed considerably from what they are at the present 
time. 

But here again we meet with exactly the same difiiculty as in 
the mammalia, in the comparative poverty of the types of birds 
now inhabiting Celebes. Although the preponderance of affin- 
ity, especially in the case of its more ancient and peculiar forms, 
ia undoubtedly with Asia rather than with Australia, yet, stitl 
mora decidedly than in the case of the mammalia, are we forbid- 
den to suppose that it ever formed a part of the old Asiatic con- 
tinent, on account of the toto^ absence of so many important and 
extensive groups of Asiatic birds. It is not single species or 
even genera, hut whole families, that are thus absent, and among 
them families which are pre-eminently characteristic of all trop- 
ical Asia. Such are the Tinialiidio, or babblers, of which there 
arc twelve genera in Borneo and nearly thirty genera in the 
Oriental Regioii, but of which one species only, hardly distin- 
guishable from a Malayan form, inhabits Celebes; the Phyllor- 
nithidfc, or green hulhnls, and the Pycnonotidje, or bulbnls, 
both absolutely ubiquitous in tropical Asia and Malaya, but uu- 



Chap. XX.] CELEBES. 423 

known in Celebes; tlie Enrylsemidfie, or gapers, found every- 
where in the great Malay islands; the Megalsemidse, or barbets; 
the Trogonidse, or trogons; and the Fhasianidse, or pheasants; 
all pre-eminently Asiatic and Malayan, but all absent from Cel- 
ebes, with the exception of the common jungle- fowl, which, 
owing to the passion of Malays for cock-fighting, may have been 
introduced. To these importsint families may be added Asiatic 
and Malayan genera by the score ; but, confining ourselves to 
these seven ubiquitous families, we must ask, Is it possible that, 
at the period when the ancestore of the peculiar Celebes mam- 
mals entered the island, and when the forms of life, though dis- 
tinct, could not have been quite unlike those now living, it could 
have actually formed a part of the continent without possessing 
representatives of the greater part of these extensive and impor- 
tant families of birds ? To get rid altogether of such varied and 
dominant types of bird-life by any subsequent process of sub- 
mersion is more difficult than to exterminate mammalia ; and we 
are therefore again driven to our former conclusion — that the 
present land of Celebes has never (in Tertiary times) been united 
to the Asiatic continent, but has received its population of Asi- 
atic forms by migration across narrow straits and intervening isl- 
ands. Taking into consideration the amount of affinity, on the 
one hand, and the isolation, on the other, of the Celebesian fauna, 
we may probably place the period of tliis earlier migration in 
the early part of the latter half of the Tertiary period ; that is, 
in middle or late Miocene times. 

Celebes not iSt7n<:tly a Continental Island, — A study of the 
mammalian and of the bird fauna of Celebes thus leads us in 
both cases to the same conclusion, and forbids us to rank it as a 
strictly continental island on the Asiatic side. But facts of a 
very similar character are equally opposed to the idea of a for- 
mer land-connection with Austmlia or New Guinea, or even 
with the Moluccas. The numerous marsupials of those coun- 
tries are all wanting in Celebes, except the phalangers of the 
genus Cuscus, and these arboreal creatures are very liable to be 
carried across narrow seas on trees uprooted by earthquakes or 
fioods. The terrestrial cassowaries are equally absent ; and thus 
we can account for the presence of all the Moluccan or Austra- 



iU 



ISLASD LIFE. 



tPABT U. 



lian types actually found in Celebes without supposing nny land- 
connection on this side during the Tertiary period. Tlie pres- 
ence of the Celebes ape in the ir^Iaiid of Batchian, and of the 
baltirusa in Bouru, can bo Buliiciently explained by a eoniewliat 
closer approximation of the respective lands, or by a few inter- 
vening islands which Lave since disappeared, or it may even be 
due to human agency. 

If the explanation now given of the peculiar features present- 
ed by the fauna of Celebes be the correct one, wc are fully jus- 
tified in classing it as an "anomalous island,'' since it jiossesses 
a small but very remarkable mammalian fauna, without ever 
having been directly united witli any continent or extensive 
land ; and, both by what it lias and what it wants, occupies bucIi 
an exactly intermediate position between the Oriental and Aus- 
tralian regions that it will perhaps ever remain a mere matter 
of opinion with which it should properly be associated. Foiin- 
ing, as it does, the western limit of such typical Australian 
groups as the marsupials among ninuimalia, and the Triehoglos- 
sida; and Hclipbagidie among birds, and being so strikingly de- 
ficient i[i all the more characteristic Oriental families and genera 
of both classes, I have always placed it in the Australian licgion ; 
but it may perhaps with equal propriety he left ont of both till 
a further knowledge of its geology enables ns to determine its 
early history with more precision. 

Peculiariti^ of the Jmt'cta of CelAes. — The only other class 
of animals in Celebes of which we have a tolerable knowledge 
is that of insects, among which we meet with peculiarities of a 
vety remarkable kind, and such as are found in no other island 
on the globe. Having already given a full account of some of 
these peculiarities in a paper read before the LinntFan Society, 
republished in my " Contributions to the Tlieory of Natural Se- 
lection," while others have been discussed in my "Geographical 
Distribution of Animals" (Vol. I,, p. 434), I will hero only briefly 
refer to them in order to see whether they accord with, or re- 
ceive any explanation from, the somewhat novel view of the 
past liistory of the island here advanced. 

The general distribution of the two best-known groups of in- 
sects — tlie buttertliea and the beetles — agrees very closely witii 



Chap. XX.] CELEBES. 425 

that of the birds and mammalia, inasmnch as Celebes forms the 
eastern limit of a number of Asiatic and Malayan genera, and at 
the same time the western limit of several Moluecan and Aus- 
tralian genera — the former perhaps preponderating, as in the 
higher animals. 

Himalayan Types of Birds and Butterflies in Celebes. — A 
curious fact of distribution, exhibited both among butterflies 
and birds, is the occurrence in Celebes of species and genera 
unknown to the adjacent islands, but only found again when 
we reach the Himalayan Mountains or the Indian Peninsula. 
Among birds we have a small yellow flycatcher {Myialestes 
helianthea)^ a flower-pecker {Pachyglossa aureolimhata\ a finch 
{Munia brumieiceps\ and a roller {Cor ados Temminckii)^ all 
closely allied to Indian (not Malayan) species — all the genera 
except Munia being, in fact, unknown in any Malay island. 
Exactly parallel cases are two butterflies of the genera Dichor- 
rhagia and Euripus, which have very close allies in the Hima- 
layas, but nothing like them in any intervening country. These 
facts call to mind the similar case of Formosa, where some of its 
birds and mammals occurred again, under identical or closely al- 
lied forms, in the Himalayas ; and in both instances they can 
only be explained by going back to a period when the distribu- 
tion of these forms was very different from what it is now. 

Peculiarities of Shape and Color in Celebesian Butterflies. — 
Even more remarkable are the peculiarities of shape and color 
in a number of Celebesian butterflies of different genera. These 
are found to vary all in the same manner, indicating some gen- 
eral cause of variation able to act upon totally distinct groups, 
and produce upon them all a common result. Nearly thirty spe- 
cies of butterflies, belonging to three different families, have a 
common modification in the shape of their wings, by which they 
can be distinguished at a glance from their allies in any other 
island or country whatever ; and all these are larger than the 
representative forms inhabiting most of the adjacent islands.* 
No such remarkable local modification as this is known to occur 



* For ontline figures of the chief types of these butterflies, see my ** Malay Archi- 
pelogo," Vol. I., p. 441, or p. 281 of the second edition. 



426 ISLAND LIFE. [Part II. 

in aoy other part of the globe ; and whatever may have been its 
cause, that cause mnst certainly have been long in action, and 
have been confined to a limited area. We have here, therefore, 
another argument in favor of the long-continued isolation of 
Celebes from all the surrounding islands and continents — an 
hypothesis which we have seen to afford the best, if not the 
only, explanation of its peculiar vertebrate fauna. 

Concluding liemarks. — If the view here given of the origin 
of the remarkable Celebesian fauna is correct, we have in this 
island a fragment of the great eastern continent which has pre- 
served to us, perhaps from Miocene times, some remnants of its 
ancient animal forms. There is no other example on the globe 
of an island so closely surrounded by other islands on every 
side, yet preserving such a marked individuality in its forms of 
life ; while, as regards the special features which characterize its 
insects, it is, so far as yet known, absolutely unique. Unfortu- 
nately, very little is known of the botany of Celebes, but it 
seems probable that its plants will to some extent partake of the 
speciality which so markedly distinguishes its animals; and 
there is here a rich field for any botanist who is able to pene- 
trate to the forest-clad mountains of its interior. 



APPENDIX TO CHAFIER XX. 427 



APPENDIX TO CHAPTER XX. 

The following list of the land birds of Celebes and the ad- 
jacent islands which partake of its zoological peculiarities, in 
which are incorporated all the species discovered up to the 
present year, has been drawn up from the following sources : 

1. A List of the Birds Known to Inhabit the Island of Celebes. By Arthur, Vis- 

count Walden, F.R.S. iTrans. ZooL Soc., 1872, Vol. VIII., pt. ii.) 

2. Intorno al Gcnere Ilermotimia. (Rchb.) Note di Tomnuiso SalvadorL (A tit 

della Reale Academia delle Scienze di Torino^ VoL X., 1874.) 

3. Intorno n Due Collezioni di Ucelli di Celebes. Note di Tommaso Salvadori. 

{Annul-: del Mm. Civ, di St. Nat. di Gtnova, Vol. VII., 1876.) 

4. Beitrage zur Omitbologie von Celebes und Sangir. Von Dr. Friedrich Briiggc- 

mann. Bremen, 1876. 
it. Intorno a Due Piccole Collezioni di Ucelli di Isole Sanghir e di Tifore. Note di 

Tommaso Salvadori. (Annali del Mus. Civ. di St. Nat, di 6'enora, Vol. IX., 

187G-77.) 
C. Intonio alle Specie di Nettarinie delle Molucche e del Gruppo di Celebes. Note 

di Tommaso Salvadori. (Atti della Reale Acad, delle Scienze di Torino^ 

Vol. XII., 1877.) 

7. Dcscrizione di Tre Nuove Specie di Ucelli, e Note intorno ad altre poco conosci- 

ulc delle Isole Sanghir. Tcr Tommaso Salvadori. (Loc. ci7.. Vol. XIII. , 
1878.) 

8. Field Notes on the Birds of Celebes. By A. B. Meyer, M.D., etc. (Ibisj 1879.) 
\K On the Collection of Birds made by Dr. Meyer during his Expedition to New 

Guinea and some Neighboring Islands. By R. Boulder Sharpe. (Mitth. d. 
kgl. Zool. Mus. Dresden, 1878. Heft 8.) New species from the Sula and 
Sanghir Islands are descnbcd. 
10. List of Birds from the Sula Islands (Elast of Celebes), >vith Descriptions of the 
New Species. By Alfred Kussel WalUce, F.Z.S. (Proc, ZooL Soc., 1862, 
p. 333.) 



428 



ISLAND LIFE. 



LIST OF LAND BIRDS OF CELEBES. 

N.B, — The Species marked with an ♦ are not included in Viscount Walden's Kst. For 

these only, an authority is usually given. 





Celebes. 


Sulals. 


SangUir I& 


Range and Remarks. 


TURDID^ 

1 . Geociclila erythronotn 

2. Monticola solitario. 

Sylviid^. 

8. Cisticola cursitans 


X 
X 

X 
X 
X 

X 
X (Meyer) 

X 

X 

X 

X 
X 
X 
X 

X 

X (Meyer) 
x' 


X 

X 

X 
X (Wall.) 


X 

X (Salv.) 


Phil., China, Japan 
Assam 


4. ** Gray! 




5. Acrocephalus orien talis. 

♦(). ** insnlaris 

7. Pratincola caprata 

*8. Gerygone flaveola (Cab.).. . 

TiMALIID/E. 

y. Tt'icbostoma Celebense 

Pycnonotid*. 
♦10. Criniger longirostris (Wall.) 

*11. ** aureus (Wrtld.). •• • 

Oriolii).*:. 
1 2. Oi iolus Celebensis 


China, Japan 
Moluccas 
Asia, Java, Timor 
(Near G.sulphurea, 
Timor) 

Orien tal gen us (near 
Bouru sp.) 

/V.or. nf O.rnrnnn. 


* 1 3. * * formosus (Cab. ) 

*14. '* frontalis (Wall.).... 

CAMrKPHAGID.*:. 

15. Graucalus ntriccps 


1 tiis^ Java) 
X(Brugg.)(Var. of Philipp. 
ep.) 

1 

Ceram. Flores 


H>. *' leucopygius 

17. *' Temniiiifkii 

1 8. Campepliaga morio 

*li). '* melanoiis 

♦20. ** Snlvadorii (JSharpc) 

21. Lalagc leucopvgialis 

♦22. " Dominica 


Moluccas 

X 1 

— Java 


23. Artamides bicolor 




♦24, ** schistaceus (Sliarpe) 


X 







LIST OF LAND BIRDS OF CELEBES. 



429 





Celebes. 


Sula Is. 


Sanghir Is. 


Range and Remarks. 


DlCRURID^. 

25. l^icruriis leticoDS 


X 

X 
X 
X 
X 
X 

X 
X 

X 

X 
X 
X 
X 
X 

X 

X 
X 

X 

X 
X 
X 

X 
X 
X 


X 

X 

X (Wall.) 

X 

X 
X 

X var. 

X 
X 

• 

X (Wall.) 

X 
X 


X 1 X 1 X till X 




♦26. ** axillaris (Salv.). . . 
♦27. " pectoralis (Wall.) 

McSCICAPIDiE. 

28. Cvornis rafisula. 




29. ** banvuroas 


Java and Borneo 


80. Mvialestes helianthea 

31. Uypothymis puella. 

33. ** Mcnadensis?.. 

♦33. Monarclia commutata 

rBruffflr.) .... J 


(Indian ally) 


♦34. Monarclia cinerascens 

PACHYCKPHALIDiE. 

35. Hylocharis sulfurirentra.... 

♦36. Pachycephala lineolata 

(Wall.) 


Moluccas 
Bourn 


♦37. Pachycephala rufescens 

♦38. Pachycephala Clio (Wall.). 

Laniidje. 
♦39. Lanius magnirostris (Merer) 

CORVID-K. 

40. Cor^'us enca 


Bouru 
Bouru 

Java 

Java 


♦41. ** nnnectens (Briigg.). 

42. ** (Gazzola) typica.. . . 

43. Strcptocitta Caledonica 

44. " torqunta. 

♦45. (Charilonii8)Albertia(Scljl.) 

Meliphagid^. 

46. Myzomela cbloroptera 

NECTARIXIIDili:. 

47. Anthreptes Malaccensis 

(Celebensis. Shelley) 

48. Chalcostethia porpbyolsema 
*49. ** anriceps 


(Nearest M, san^wi- 
noltnta of Aus.) 

Siam, Bfulaya 
Temate 


♦oO. " Sangirensis (Meyer). 

51. Aracbnectbra franata 

52. Nectarophila Grayi ........ 

53. ^thopvga flavostriata. 

♦54. ** Beccarii (Salv.) 

♦55. ** Duyvenbodei (Scbl.). 

56. Zosterops intermedia. 

57. * ' ntrifrons 


Moluccas and K. 
Guinea. 

(An Oriental genus) 
Lombok 


58. Dicsum Celebiciim 





480 



ISLAND LIFE. 



ColobML 



•59. I>ic»am8tnghiroiiie(S«Iv.) 
60. FachygloMii aureoUmlMUa. . 



HlRUKDIHIDA 

61. Hirandogattiiralis., 

62. ** Jafanica. . 



PfX>CBIDJB. 

68. Miinia oryaifora. . . . 
6i. '* niioria. 

65. " Molucca 

66. ** branneicept.. 



•67. 



t( 



Jiigori. 



SruBinDiB. 

68. Basilornii Cdebensia. . 

69. Acridotherai cineroas. 
7<l. Starnia pyrrliogenjrt. - 
71. Calomifl neglacta 

•7S. '' metaUica.... 
78. Enodes efythrophrjs. . 
74. Scistiroatrum Fagei. . . 



ASTAMIDJB. 

75. Artamas monachus 

76. ** leiuiorhjnchns. . . . 



MOTACILLID.K. 

77. Conrdalla Gustavi 

78. Budytes viridis... 
•79. Colobatefl melanope=(Mo- 

tac. flulfurco. Bi-iigg.)* • • 

PlTTIDA. 

80. Fitta Forateni 

♦81. 

82. 
*«3. 
•84. 
•85. 



Sangliirana (Schl.). . 

Celebensis 

imlliceps (Briigg.) — 
cieruleitorqaes (Salv.) 
irena (=cra8»irostri!*) 



X 
X 



X 
X 
X 
X 



xC&Tejer) 



X 
X 
X 
X 

x{Bragg.) 

X 
X 



X 
X 



X 
X 



Bala la 



X 
X(WaU.) 



Suighlria 



X 
X 



X var. 



X 
X 



PlCID.«. 

8f>. MuUeripicus fnlvus 

87. Yungipicus Temminckii. . . . 

CuCOLIDiK. 

88. Khamphococcyx culorhyn- 

cbas i 

89. Centropus Celcbensiu. 

90. ** nffiiiis I 

91. '* Javanensis 

92. Cuculiis canoras 

98. Cacomantes lanceolatus. . . . ; 



X 

X 



X (Wall. ) 



X 
X 



X 
X 
X 
X 
X 
X 



Induin Kegion 
Indo-Malaya 



Jara 

JaTa 

Molaccfli 

(Near M, m^rmii- 

jfus, India) 
Philippine 



Range and Remarka. 



Afnlaya 
Afolaccai 



Af alaj ArcbipeL 

Java, Moluccas 
China, Fliilipp. 



Timor, Temate? 



Java 

Java, Borneo 

Java 



LIST OF LAND BIRDS OF CELEBES. 



431 





Colebca 


Sula 18. 


Sasgtair Is. 


Rango and Remarks. 


94. Cncomantcs sepulchrnlis.. . 

95. llierococcyx crassisostris.. 

96. Eudvnamis mclanorhyncha 
♦07. '" facialis (Wall.> 
♦98. ** orientalis 

99. Scvthrops Nuvsehollandis. 

CORACIIDA. 

100. Coracias Temroinckii 

101. Eurystomus orientalis 

Meropida. 

102. Meropogon Forsteni 

103. Merops Philippinus 

104. ** oniatus 


X 

X 
X 

X 

X 
X 

X 
X 
X 

X 
X 
X 

X 
X 
X 
X 
X 
X 
X 
X 

X 
X 

X 
X 
X 

X 
X 
X 
X 

X 
X 
X 

X 
X 


X 

X 

X 

X 
X 

X 
X 

X 
X 

X (Wall.) 

X 


x(Biugg.) 

X 

X 
X 

X 
X 


Moluccas ? 
Molaccas, etc. 

Asia 

Oriental Region 
Java, Aastralia 

Molaccas 
Indo-Malaya 

(Allied to Mol. sp.) 


Alcedinidje. 

10.>. Alcedo Moluccensis 

106. •' Asiatica..: 


107. Pelargopsismelanorhyncliu 

♦108. Ceyx Wallacei (Shai-pe) . . 

109, CeycoDsis fallax 


110. Ualcvon cliloris 


All Archipel. 
All Archipel. 


111. ** sancta 


112. ** Forsteni 


113. ** rufa 

1 14. Monacbalcyon princeps. . 
♦115. ** cyanocephala(BrUgg.) 

1 16. Cittura cvanotis. 




♦117. " Sanghirensis (Schl.) 

BCCEUOTID^. 

118. llydrocissa exarata 

119. Crunorhinus cassidix 

CAPRIMULGIDiE. 

1 20. Capriraulgus affinis. 

121. ** sp 




122. Lyncornis macropterus 

Ctpselidje. 

123. Dendrochelidon Wallace!.. 

124. CoUocalia esculenta 

1 25. * * faciphnga. 

126. Chsetura ffimutea 


Mol. to Ara Is. 
India, Java 
India. Java 


PSITTACI. 

1 27. C/Ucatiia sulpharea 

1 28. Prionitui-us platurus 

129. " flavicans 

♦130. Platycerciis dorsalis, var.. . 

131. Tanygnatbus Mullen 

♦132. '** megalorhynchus 


Lombok, Flores 

N. Guinea? 

Moluccas. Anis.n. 
Menado (Meyer) 



432 



ISLAND LIFE. 





Celebe& 


Sula Is. 


Sanghir Is. 


Range and Remarks. 


*133. Tanygnathns Luzoniensis. 

134. Loriculus stigmatus 

♦186. ** quadricolor (Wald.) 

136. " Sclateri 


X 
X 

? 
X 

X 

X 

X 
X 

X 
X 

X 
X 
X 
X 

X 
X 
X 

X (Meyer) 

X 
X 
X 
X 

X 
X Mever 

» 

X 
X 
X 
X 
X 
X 

X 
X 
X 
X 
X 
X 


X 
X 

X 
X 

X 

X 

X 
X 

X var. 


X(Briigg.) 

X 

X 

X var. 

Sanglii- 

rensis. 

X var. 

Xanthor- 

rhoa. 

Salv. 

X (Salv.) 

X 
X 

X 
X 

X 


Togian I*., Gulf 
of Tomini 


187. ** exilis 




♦188. ** catamene (Schl.)... 

139. Trichoglossus ornatus 

♦140. " flavoviridis (Wall.) 

141. ** Meyeri 




♦142. Eos histrio = E. coccinea 

COLUMBA. 

143, Treron vernans 


MalacyJarayPhilip. 


144. ** griseicauda 

145. FtiloDas formosus 


146. ** melanocephalus.. 

147. ** gularis. 


Java, Lombok 


♦148. " Fischeri (Brugg.). 

149. Carpophaga paulina 

♦150. ** pulchella(Wald.).. 

151. ** concinna 


Togian If!. {Ann.and 
Mag. Nat, Hist, 

1874.) 
Ke Goram 


1 52. " rosacea 


Gilolo. Timor 


♦153. ** pa;cilorrhoa(Briigg.) 
154. ** luctuosa 




♦155. ** bicolor 


N. Guinea. Moluc. 


156. ** radiata 

157. ** Forsteni 




158. Macropygia albicapilla 

1 50. ** Macassariensis 

♦160. ** Sanghirensis(Salv.) 

161. Turacoeiia Menaderusis 

♦162. Keiinvardtifiias lieinwardti 

1 6.'J. Turtur tiiirina 


Moluccas and N.G. 
NlnlaviL. IVIoIurons 


164. Clialcophaps Stephani 

165. *' Indica 

1 ()6. I*liloga;nas trisiiginata 

1 ()7. ticoijclia striata 


New Guinea 
Indiaand Archipcl. 

Pbina .Tavn Tx^mb 


1 68. CaUuuas Nicobarica 

Gallina:. 

169. Gallus Bankiva 


Malacca and New 
Guinea 

•Tavn Timor 


1 70. Coturiiix minima 


{ynwofCatinensis) 


171. Turnix niHIatiis 


♦172. '* Beccnrii (Salv.)... 

173. Megapodius Gilberti 

1 74. Megaceplialoii tiialleo 





LIST OF LAND BIRDS OF CELEBES. 



433 





Celebca 


Sula la. 


Sangbir I& 


Raogo and Romarka 


ACCIPITRES. 

] 75. Circus assimilis 


X 
X 
X 
X 
X 

X 

X 

X 
X 
X 
X 
X 
X 
X 
X 
X 

X 
X 
X 
X 

X 
X 
X 
X 
X 

X 


I X I X X X 


X 


Australia 


1 76. Astiir sriseiceDs 




♦177. *' tennirostris (Briigg.) 

178. ** rhodognstra. 

179. '* trinotata 




♦180. Accipiter Sulaensis (Schl.) 

181. ** Soloensia. 

182. Neopus Malnyensis 

183. Spizaetns lanceolatas 

184. HaliaBtus leucogaster 

185. Spilomis rufipectos 

186. Butastur liventer , 


Malacca and New 

Guinea 
Nepaul, Sum., Java, 

Moluccas 

Oriental Region 
Java. Timor 


187. " Indicus. 


India. Java 


188. IXnliastnr leucostemiis. — 

189. Milvusnffinis 


MoluccaSfN.Gninea 
Australia 


1 90. Klanus hypoleacus 

191. FemU ptilorhyncha. 

(var. Cclebensis) 

192. Baza erythrothorax 

1 93. Faico severus 


? Java, Borneo 
(Var, Java, etc.) 

All Archipel. 
Java, Moluccas 
India, Malaya 


194. Cerchneis Molaccensis.. . . . 

195. PoliosBtas humilis. 

STRIOIDiE. 

196. Athene punctulata 

197 ** ochracea 


1 98. ScoDS maeicus 


Amboyna, etc. ? 
Flores.Madafirascar 


199 ** Menadensis 


200. Ninox JtiDonicus 


China, Japan 
MoIacca 


*20l. " scutulata 


202. Strix Rosenbergi 





28 



434 ISLAND LIFE. [Past II. 



CHAPTER XXI. 

ANOMALOUS ISLANDS: NEW ZEALAND. 

Position nnd Physical Featares of New Zealand. — Zoological Character of New Zen- 
land* — Mammalia. — Wingless Birds Living and Extinct. — Recent Existence of th« 
Moa. — Past Changes of New Zealand Deduced from its Wingless Birds. — Birds 
and Reptiles of New Zealand. — ConcIu.«ions from the Pecoliarities of the New Zea- 
land Fanna. 

The fauna of Xew Zealand has been so recently described, 
and its bearing on the past history of tlie islands so fully dis- 
cussed in njy large work already referred to, that it would not 
be necessary to introduce the subject again, were it not that we 
now approach it from a somewhat diflferent point of view, and 
with some important fresh material, which will enable us to ar- 
rive at more definite conclusions as to the nature and origin of 
this remarkable fauna and flora. The present work is, besides, 
addressed to a wider class of readers than my former volumes, 
and it would be manifestly incomplete if all reference to one 
of the most remarkable and interesting of insular faunas were 
omitted. 

The two great islands which mainly constitute Xew Zealand 
are together about as large as the kingdom of Italy. They 
stretch over thirteen degrees of latitude in the warmer portion 
of the south temi)erate zone, tlnn'r extreme points corresponding 
to the latitudes of Vienna and Cyprus. Their climate through- 
out is mild and efjuable, their vegetation is luxuriant, and des- 
erts or uninhabitable regions are as comjdctely unknown as in 
our own islands. 

The biological structure of these islands has a decidudlv con- 
tinental character. Ancient sedimentary rocks, granite, and mod- 
ern volcanic formations abound; gold, silver, copper, tin, iron, 
and coal are plentiful ; and there are also some considerable de- 



Caxr. TTT] 



NEW ZEALAND. 



435 



posits of earl/ or late Tertiary age. Tlie Secondary rocka aloiio 
are very scantily developed, and bucIi fragments as exist aro 
chiefly of Cretaceous age, often not clcaily separated from the 
succeeding Eocene beds. 

The position of New Zealand in the great Sonthern Ocean, 
about I'lOO miles distant from tho Anstralian continent, is very 
isolated. It is surrounded hy a modcratuly deep ocean ; hut the 
form of the sea-bottom is peculiar, and nmy help us in the sotn- 




tion of some of the anomalies presented by its living produc- 
tions. The line of 2<lU fathoms encloses the two islands and ex- 
tends their area considerably; but the lOOU-fathom line, which 
indicates the land-area that wonld be piodiiced if the sea-liottom 
were elevated fiOOO feet, has a very remarkable conformiUioii, 
extending in a broad mass wcstwai'd, and then gending out two 
great arms, one reaching to beyond Lord Howe's Island, while 
the other stretches over Norfolk Island to tho great barrier reef, 
thus forming a connecliuii witii Iropicnl Anstmlia and New 



436 ISLAND LIFE. [Part II. 

Gninea. Temperate Australia, on the other hand, is divided 
from New Zealand by an oceanic gulf about 700 miles wide and 
between 2000 and 3000 fathoms deep. The 2000-fathom line 
embraces all the islands immediately round New Zealand ; and 
a submarine plateau at a depth somewhere between one and two 
thousand fathoms stretches southward to thfe antarctic conti- 
nent. Judging from these indications, we should say that the 
most probable ancient connections of New Zealand were with 
tropical Australia and New Guinea, and perhaps, at a still more 
remote epoch, with the great southern continent by means of 
intervening lands and islands ; and we shall find that a land-con- 
nection or near approximation in these two directions at remote 
periods will serve to explain many of the remarkable anomalies 
which these islands present. 

Zoological Character of New Zealand, — ^We see, then, that 
both geologically and geographically New Zealand has more of 
the character of a "continental" than of an "oceanic" island; 
yet its zoological characteristics are such as almost to bring it 
within the latter category, and it is this which gives it its 
anomalous character. It is usually considered to possess no in- 
digenous mammalia; it has no snakes, and only one frog; it 
possesses (living or quite recently extinct) an extensive group of 
birds incapable of flight; and its productions generally are won- 
derfully isolated, and seem to bear no predominant or close rela- 
tion to those of Australia or any other continent. These are the 
characteristics of an oceanic island; and thus we find that the 
inferences from its physical structure and those from its forms 
of life directly contradict each other. Let us see how far a closer 
examination of the latter will enable us to account for this ap- 
parent contradiction. 

Mammalia of New Zealand, — The only undoubtedly indige- 
nous mammalia appear to be two species of bats, one of whicli 
{Scotoj)hllu8 tuherculatus) is, according to Mr. Dobson, identical 
with an Australian form, while the other {Myf^tachia iuhercu- 
latd) forms a very remarkable and isolated genus of Emballonu- 
ridffi, a family which extends throughout all the tropical rec^ions 
of the globe. The genus Mystacina was formerly considered to 
belong to the American Phyllostomidse, but this has been shown 



438 ISLAND LIFE. [Part II. 

tains of the South Islaud of a small otter-like animal. Dr. Haast 
has seen its tracks, resembling those of our European otter, at a 
height of 3000 feet above the sea in a region never before trod- 
den by man; and the animal itself was seen by two gentlemen 
near Lake Heron, about seventy miles due west of Cliristchurch. 
It was described as being dark-brown and the size of a large rabbit. 
On being struck at with a whip, it uttered a shrill yelping sound 
and disappeared in the water.* An animal seen so closely as to 
be struck at with a whip could hardly have been mistaken for a 
dog — the only otlier animal that it could possibly be supposed 
to have been — and a dog would certainly not have "disappeared 
in the water." This account, as well as the footsteps, points to 
an aquatic animal ; and if it now frequents only the high alpine 
lakes and streams, this might explain why it has never yet been 
captured. Hochstetter also states that it has a native name — 
Waitoteke — a striking evidence of its actual existence ; while a 
gentleman wlio lived many years in the district assures me that 
it is universally believed in by residents in that paTt of New 
Zealand. The actual capture of tliis animal, and the determi- 
nation of its characters and affinities, could not fail to aid us 
greatly in our speculations as to the nature and origin of the 
New Zealand fauna.' 

WingUssIiirds^ Living and Extinct, — Ahnost equally valuable 



* Ilochstetter's ** New Zealnnd," p. IGl, note. 

' The aiiiinnl described by Captain Cook as having been seen at Pickersgill Har- 
bor in Dusky Hay (Cook's *' Second Voyage," Vol. I., p. 08) may liave been the same 
creatiu'e. lie says, '* A four-footed animal was seen by three or four of our people ; but 
as no two gave ihe same description of it, I cannot say what kind it is. All, how- 
ever, agreed that it was about the size of a cat, with short legs, and of a mouse-color. 
One of the seamen, and he who had the best view of it, said it had a bushy tail, and 
was the most like a jackal of any animal he knew." It is suggestive that so far as 
the points on which '*all agreed" — the size and the dark color — this descri])tion 
would answer well to the animal so recently seen, while the *' short legs " corre- 
spond to the ottci-like tracks, and the thick tail of an otter like animal m:iy well have 
appeared *' bushy "' when the fur was dry. It has been suggested that it was only 
one of the native dogs ; but as none of those who saw it took it for a dog, and the 
points on which they all agreed are not dog-like, we can hardly accept this explana- 
tion ; while the actual existence of an unknown animal in New Zealand of corre- 
sponding size and color is confirmed by this account of a similar animal having been 
seen about a century ago. 



Chap. XXI.] NEW ZEALAND. 439 

with mammalia in affording indications of geographical changes 
are the wingless birds for which New 2Sealand is so remarkable. 
These consist of four species of Apteryx, called by the natives 
" kiwis " — creatures which hardly look like birds, owing to tlie 
apparent absence (externally) of tail or wings and the dense cov- 
ering of hair-like feathers. They vary in size from that of a 
small fowl up to that of a turkey, and have a long slightly 
curved bill, somewhat resembling that of the snipe or ibis. Two 
species appear to be confined to the South Island and one to the 
North Island ; but all are becoming scarce, and they will, no doubt, 
gradually become extinct. These birds are generally classed 
with the Struthiones, or ostrich tribe, but they form a distinct 
family, and in many respects differ greatly from all other known 
birds. 

But, besides these, a number of other wingless birds, called 
"moas," inhabited New Zealand during the period of human 
occupation, and have ouly recently become extinct. These were 
much larger birds than the kiwis, and some of them were even 
larger than the ostrich, a specimen of Dinornis 7naximu8 mount- 
ed in the British Museum in its natural attitude being eleven 
feet high. They agreed, however, with the living Apteryx in 
having four toes, and in the character of the pelvis and some 
other parts of the skeleton ; while in their short bill and in some 
important structui*al features they resembled the emu of Aus- 
tralia and the cassowaries of New Guinea.* No less than eleven 
distinct species of these birds have now been discovered ; and 
their remains exist in such abundance — in recent fluviatile de- 
posits, in old native cooking -places, and even scattered on the 
surface of the ground, that complete skeletons of several of 
them have been put together, illustrating various periods of 
growth from the chick up to the adult bird. Feathers have 
also been found attached to portions of the skin, as well as the 
stones swallowed by the birds to assist digestion, and eggs, some 
containing portions of the embryo bird ; so that everything con- 



* Owen, "On the Genus Dinornis," TransactionB of thB Zoological Society j VoL 
X., p. 184; Mivart, " On the Axial Skeleton of the Strathionidae,'' Tramactiona of 
the Zoological Society , Vol. X., p. 51. 



440 ISLAND LIFa [Pakt U. 

firms the statements of the Maoris — that their ancestors foand 
these birds in abundance on the islands ; that they hnnted them 
for food ; and that they finally exterminated them only a short 
time before the arrival of Europeans.* Bones of Apteryx are 
also fonnd fossil, but apparently of the same species as the liv- 
ing birds. How far back in geological time these creatures or 
their ancestral types lived in New Zealand we have as yet no 
evidence to show. Some specimens have been found under a 
considerable depth of fluviatile deposits which may be of Qua- 
ternary or even of Pliocene age ; but this evidently affords ns 
no approximation to the time required for the origin and devel- 
opment of such highly peculiar insular forms. 

Past Changes of New Zealand Deduced from its Wingless 
Birds,-^lt has been well observed by Captain Ilutton, in his in- 
teresting paper already referred to, that the occurrence of such a 
number of species of Struthious birds living together in so small 
a country as New Zealand is altogether unparalleled elsewhere 
on tlie globe. This is even more remarkable when we con- 
sider that the species are not equally divided between the two 
islands, for remains of no less than ten out of the eleven known 
species of Dinornis have been found in a single swamp in the 
Soutli Island, where also three of the species of Apteryx oc- 



' Tlie recent existence of the mon,and its having been exterminnted by the Maoris, 
appears to Ik; at length set at rest by the statement of Mr. John White, a gentleman 
who has been collecting materials for a history of the natives for thirty-five years, who 
has been initiated by their priests into all the mysteries, and is said to **know more 
about the history, habits, and customs of the Maoris than they do themselves." His 
information on this subject was obtained fiom old natives long beftne the controversy 
on the subject arose. He says that the histories and songs of tho Maoris abound 
in allu>ions to the moa, and that they were able to give full accounts of **it8 habits, 
food, the season of the year it was killed, its api)earance, strength, and all the numer- 
ous ceremonies which were enncted by the natives liefore they began the hunt ; the 
mode of hunting, how cut up, how cooked, and what wood was used in the cooking, 
with an account of its nest, and how the nest wris made, where it usuallv lived, etc." 
Two pages are occupied by these details, but they are only given from memory, and 
Mr. White promises a full account from his MSS. Many of the details given coitc- 
spond with facts ascertained from the discovery of native cooking-places with moa's 
bones ; and it seems quite incredible that such an elaborate and detailed account 
should be all invention (see Transactions of the Xew Zealand /«.^/iV«/^r, Vol. Vlll., 
p. 75)). 



Chap. XXL] NEW ZEALAND. 441 

cur. The New Zealand Struthiones, in fact, very nearly equal in 
number those of all the rest of the world, and nowhere else do 
more than three species occur in any one continent or island, 
while no more than two ever occur in the same district. Thus 
there appear to be two closely allied species of ostriches inhab- 
iting Africa and Southwestern Asia respectively. South America 
has three species of Ehea, each in a separate district. Australia 
has an eastern and a western variety of emu, and a cassowary in 
the north ; while eight other cassowaries are known from the 
islands north of Australia — one from Ceram, two from the Am 
Islands, one from Jobie,one from New Britain, and three from 
New Guinea — but of these last," one is confined to the northern 
and another to the southern part of the island. 

This law, of the distribution of allied species in separate areas 
— which is found to apply more or less accurately to all classes 
of animals — is so entirely opposed to the crowding together of 
no less than fifteen species of wingless birds in the small area of 
New 2^aland that the idea is at once suggested of great geo- 
graphical changes. Captain Ilutton points out that if the isl- 
ands from Ceram to New Britain were to become joined togeth- 
er, we should have a large number of species of cassowary (per- 
haps several more than are yet discovered) in one land area. If, 
now, this land were gradually to be submerged, leaving a cen- 
tral elevated region, the different species would become crowded 
together in this portion, just as the moas and kiwis were in New 
Zealand. But we also require, at some remote epoch, a more 
or less complete union of the islands now inhabited by the sep- 
arate species of cassowaries, in order that the common ancestral 
form which afterwards became modified into these species could 
have reached the places where they are now found ; and this 
gives ns an idea of the complete series of changes through which 
New Zealand is believed to have passed in order to bring about 
its abnormally dense population of wingless birds. First, we 
nmst suppose a land-connection with some country inhabited 
by Struthious birds, from which the ancestral forms might be 
derived ; secondly, a separation into many considerable islands, 
in which the various distinct species might become differen- 
tiated ; thirdly, an elevation bringing about the union of these 



442 ISLAND LIFE. IT^kt II. 

ifelands to onite the distinct species in one area ; and. fourthly, a 
6ub&idcnce of a large part of the area, leaving the present islands 
with the various species crowded together. 

If New Zealand has really gone through such a series of 
clianges as here suggested, some proofs of it might perhaps be 
obtained in the outlying islands which were once, presumably, 
joined with it. And this gives great importance to the state* 
ment of the aborigines of the Chatham Islands that the Apteryx 
formerly lived there, but was exterminated about 1835. It is 
to be hoped that some search will be made here, and also in Xor- 
folk Island, in both of which it is not improbable remains of 
Apteryx or Dinomis might be discovered. 

So far we find nothing to object to in the speculations of 
Captain Hutton, with which, on the contrary, we almost wholly 
concur; but we cannot follow him when he goes on to suggest 
an antarctic continent uniting New Zealand and Australia vrith 
South America, and probably also with South Africa, in order 
to explain the existing distribution of Struthious birds. Our 
best anatomists, as wc have seen, agree that both Dinornis and 
Apteryx are more nearly allied to the cassowaries and emus than 
to the ostriches and rheas; and we see that the form of the 
sea-bottom su^ests a former connection with Nortli Australia 
and New Guinea — the very region where these types most 
abound, and where in all probability they originated. Tlie sug- 
gestion that all the Struthious birds of the world sprang from 
a common ancestor at no very remote period, and that their ex- 
isting distril)ution is due to direct land communication between 
the countries tliey now inhabit, is one utterly opposed to all 
sound principles of reasoning in questions of geographical dis- 
tribution ; for it depends upon two assumptions, both of which 
are at least doubtful, if not certainly false — tlie first, that their 
distribution over the globe has never in past ages been very 
different from what it is now; and the second, tJiat tlie ances- 
tral forms of these birds never liad the power of fliglit. As to the 
iirst assumption, we have found in almost every case tliat groups 
now scattered over two or more continents formerly lived in 
intervening areas of existing land. Thus, the marsupials of 
South America and Australia are connected by forms which 



Chap. XXL] NEW ZEALAND. 443 

lived in North America and Europe; the camels of Asia and 
the llamas of the Andes had many extinct common ancestors in 
North America ; the lemura of Africa and Asia had their ances- 
tors in Europe, as did the trogons of South America, Africa, 
and tropical Asia. But, besides this general evidence, we have 
direct proof that the Struthious birds had a wider range in past 
times than now. Remains of extinct rheas have been found in 
Central Brazil, and those of ostriches in North India ; while re- 
mains believed to be of Struthious birds are found in the Eo- 
cene deposits of England ; and the Cretaceous rocks of North 
America have yielded the extraordinary toothed bird Hesper- 
ornis, which Professor O. Marsh declares to have been " a car- 
nivorous swimming ostrich." 

As to the second point, we have the remarkable fact that all 
known birds of this group have not only the rudiments of wing- 
bones, but also the rudiments of wings; that is, an external 
limb bearing rigid quills or largely developed plumes. In the 
cassowary these wing-feathers are reduced to long spines like 
porcupine-quills, while even in the Apteryx the minute external 
wing beare a series of nearly twenty stiflE quill-like feathers.* 
These facts render it probable that the Struthious birds do not 
owe their imperfect wings to a direct evolution from a reptilian 
type, but to a retrograde development from some low form of 
winged birds^ analogous to that which has produced the dodo 
and the solitaire from the more highly developed pigeon-type. 
Professor Marsh has proved that, so far back as the Cretaceous 
period, the two great forms of birds — those with a keeled sternum 
and fairly developed wings, and those with a convex keelless 
sternum and rudimentary wings — already existed side by side; 
while in the still earlier Archseopteryx of the Jurassic period 
we have a bird with well-developed wings, and therefore prob- 
ably with a keeled sternum. We are evidently, therefore, very 
far from a knowledge of the earlier stages of bird-life, and our 
acquaintance with the various forms that have existed is scanty 
in the extreme ; but we may be sure that birds acquired wings 

> See iignre in Transactions of the New Zealand Institute^ Vol. 1 1 L, Plate 12 6, 
Fig. 2. 



444 ISLAND LIFE. [Past II. 

and feathers, and some power of flight, before tbev developed 
a keeled stemnni, since we see that bats with no such keel fljr 
very well. Since, therefore, the Stmthions birds all have per- 
fect feathers, and all have mdimentary wings which are ana- 
tomically those of tme birds, not the rudimentary forelegs of 
reptiles, and since we know that in many higher gronps of birds 
— as the pigeons and the rails — ^the wings have become more or 
less aborted, and the keel of the sternum greatly reduced in size 
by disuse, it seems probable that the very remote ancestors of 
the rhea, the cassowary, and the Apteryx were true flying birds, 
although not perhaps provided with a keeled sternum, or pos- 
sessing very great powers of flight. But, in addition to the pos- 
sible ancestral power of flight, we have the undoubted fact that 
the rhea and the emu both swim freely, the former having been 
seen swimming from island to island off the coast of Patagonia. 
This, taken in connection with the wonderful aquatic ostrich 
of the Cretaceous period discovered by Professor Mai'sh, opens 
up fresh possibilities of migration ; while the immense antiquity 
thus given to the group, and their universal distribution in past 
time, render all suggestions of special modes of communication 
between the parts of the globe in which their scattered remnants 
noio happen to exist altogether superfluous and misleading. 

The bearing of this argument on our present subject is that, 
so far as accounting for the presence of wingless birds in Xew 
Zc«aland is concerned, we have nothing whatever to do with any 
possible connection by way of a southern continent or antarc- 
tic islands with South America and South Africa, because the 
nearest allies of its nioas and kiwis arc tlie cassowaries and emus ; 
and we have distinct indications of a former land-extension tow- 
ards North Australia and Xew (xuinea, which is exactly what we 
require for the original entrance of the Struthious type into tlie 
New Zealand area. 

Whifjal Jilrth and Low^'r Vertehrates of Xew Z^Hiland. — Hav- 
ing given a pretty full account of the New Zealand fauna else- 
where,* I need only here point out its bearing on the hypothesis 
now advanced, of the former land-connection liavinu: been with 



1 (i 



Gcogrnphicnl Distribution of Animnl.'*," Vol. I., p. 4.'iO. 



CiiAP.XXL] NEW ZEALAND. 445 

North Australia, New Guinea, and the "Western Pacific islands, 
rather than with the temperate regions of Australia. 

Of the Australian genera of birds which are found also in 
New Zealand, almost every one ranges also into New Guinea 
or the Pacific islands, while the few that do not extend beyond 
Australia are found in its northern districts. As regards the 
peculiar New Zealand genera, all whose affinities can be traced 
ai-e allied to birds which belong to the tropical parts of the 
Australian Region ; wliile the starling family, to which four of 
tlie most remarkable New Zealand birds belong (the genera 
Creadion, Heterolocha, and Callseas), is totally wanting in tem- 
perate Australia and is comparatively scarce in the entire Aus- 
tralian Region, but is abundant in the Oriental Region, with which 
New Guinea and the Moluccas are in easy communication. It 
is certainly a most suggestive fact that there are more than six- 
ty genera of birds peculiar to the Australian continent (with 
Tasmania), many of them almost or quite confined to its tem- 
perate portions, and that no single one of these should be repre- 
sented in temperate New Zealand.* The affinities of the living 
and more liighly organized no less than those of the extinct and 
wingless birds strikingly accord with the line of communication 
indicated by the deep submarine bank connecting these temper- 
ate islands with the tropical parts of the Australian Region. 

The reptiles, so far as they go, are quite in accordance with 
the birds. The lizards belong to three genera — Hinulia and 
Mocoa, which have a wide range in the Eastern tropics and the 
Pacific and Malayan regions, as well as Australia ; and Naulti- 
nus, a genus peculiar to New Zealand, but belonging to a family 
(Geckotidae) spread over the whole of the warmer parts of the 
world. Australia, on the other hand, has three small but pecul- 
iar families, and no less than thirty-six peculiar genera of liz- 
ards, many of which are confined to its temperate regions, but 

no one of them extends to temperate New Zealand. The ex- 

t 

* In my "Geographical Distribution of Animals," Vol. I., p. 541, 1 have given two 
peculiar Australian genera (^Orthonyx and Tribonjfx) as occurring in New Zealand. 
But the former has been found in New Guinea, while the New Zealand bird is con- 
sidered to form a distinct genus, Clitonyx ; and the latter inhabits Tasmania, and 
was recorded from New Zealand through an error (see /6t5, 1873, p. 427^. 



44^ ISLAND LUX. [Par II. 



traordinarr Ifzard-like Hatteria punctata of Xew Zealand forms 
of itself a distinct order of reptiles, in some respects intermedi- 
ate between lizards and crocodiles, and having therefore no af- 
finity with any living animaL 

The only representative of the Amphibia in New Zealand is 
a fiolitarj frog of a peculiar genus (Liopelma Hochiftetterh ; bot 
it has no affinity for any of the Australian frogs, which are nu- 
merous, and belong to eleven distinct families : while the Lio- 
pelma belongs to a Tery different family (BombinatoridseK con- 
fined to Europe and temperate South America. 

Of the fresh-water fishes we need onlv sav here that none 
Ijelong to peculiar Australian types, but are relateil to those of 
temperate South America or of Asia. 

T^e Invertebrate classes are comparatively little known, and 
their modes of dispersal are so varied and exceptional that the 
facts presented by their distribution can add little weight to 
those already adduced. We will therefore now proceed to the 
conclusions wliich can fairly be drawn from the general facts of 
New Zealand mitural historv alreadv known to us. 

Jjeductiormfroia the Peculiarities of the Xc^c Zt aland Fauna. 
— The total absence Tor extreme scarcitv) of mammals in New 
Ze'dland obliires us to place its union with North Australia and 
Ncv/ Guinea at a very remote epoch. AVe must either go back 
to a time when Australia itself liad not vet received the ances- 
tral forms of its present marsupials and niouotrenies. (»r we must 
suppose that the portion of Australia with which New Zealand 
was coimected was then itself isolated from the mainland, and 
was thus without a mammalian population. We shall sec in 
our next chapter that there are certain facts in the distribution 
of plants, no less than in the geoloo^ieal structure of the country, 
which favor the latter view. iJut we must on any supposition 
plaee the union very far back, to account for the total want of 
identity between the winged birds of New Zealand and those 
]>eculiar to Australia, and a similar want of accordance in the 
lizards, the fresh-water lishes, an<l the more important insect- 
groups of the two countries. From what we know of the lonir 
ge(dogical duration of the generic types of these groups, we 
must certainly go back to the earlier portion of the Tertiary 



Chap. XXL] NEW ZEALAND. 447 

period at least, in order that there should be such a complete 
disseverance as exists between the characteristic animals of the 
two countries ; and we must further suppose that, since their 
separation, there has been no subsequent union or sufiScientlj 
near approach to allow of any important intermigration, even 
of winged birds, between them. It seems probable, therefore, 
that the Bampton shoal, west of New Caledonia, and Lord Howe's 
Island farther south, formed the western limits of that exten- 
sive land in which the great wingless birds and other isolated 
members of the New Zealand fauna were developed. Whether 
this early land extended eastward to the Chatham Islands and 
southward to the Macquaries, we have no means of ascertaining ; 
but as the intervening sea appears to be not more than about 
1500 fathoms deep, it is quite possible that such an amount of 
subsidence may have occurred. It is possible, too, that there 
may have been an extension northward to the Kcrmadec Islands, 
and even farther to the Tonga and Fiji Islands, though this is 
hardly probable, or we should find more community between 
their productions and those of New Zealand. 

A southern extension towards the antarctic continent at a 
somewhat later period seems more probable, as affording an easy 
passage for the numerous species of South American and ant- 
arctic plants, and also for the identical and closely allied fresh- 
water fishes of these countries. 

The subsequent breaking -up of this extensive land into a 
number of separate islands in which the distinct species of moa 
and kiwi were developed, their union at a later period, and the 
final submergence of all but the existing islands, are pure hy- 
potheses, which seem necessary to explain the occurrence of so 
many species of these birds in a small area, but of which we have 
no independent proof. There are, however, some other facts 
which would be explained by it, as the presence of three peculiar 
but alh'cd genera of starlings, the three species of parrots of the 
genus Nestor, and the six distinct rails of the genus Ocydromus, 
as well as the numerous species in some of the peculiar New 
Zealand genera of plants, which seem less likely to have been 
developed in a single area than when isolated, and thus pre- 
served from the counteracting influence of intercrossing. 



448 ISL^VND LIFE. [Part II. 

In the present state of onr knowledge, those seem all the con- 
clusions we can arrive at from a study of the New Zealand fauna ; 
but as we fortunately possess a very full and accui*ate knowledge 
of the flora of New Zealand, as well as of that of Australia and 
the south temperate lands generally, it will be well to see liow 
far these conclusions are supported by the facts of plant-distri- 
bution, and what further indications they aflford us of the early 
history of these most interesting countries. This inquiry is of 
sufficient importance to occupy a separate chapter. 



Chap.XXIL] the flora OF NEW ZEALAND. 449 



CHAPTER XXII. 

THE FLORA OF NEW ZEALAND : ITS AFFINITIES AND PROBABLE 

ORIGIN. 

lielations of the New Zealund Flora to that of Australia. — General Features of the 
Australian Flora. — The Floras of Southeastern and Southwestern Australia. — Geo- 
logical Explanation of the Differences of these two Floras. — The Origin of the Aus- 
tralian Element in the New Zealand Flora. — Tropical Character of the New Zea- 
land Flora Explained. — Species Common to New Zealand and Austrolia mostly 
Temperate Forms. — Why Easily Dispersed Plants have often Restricted Ranges. — 
Summary and Conclusion on the New Zealand Flora. 

Although plants have means of dispersal far exceeding those 
possessed by animals, yet as a matter of fact comparatively few 
species are carried for very great distances, and the flora of a 
country taken as a whole usually affords trustworthy indications 
of its past history. Plants, too, are more numerous in species 
than the higher animals, and are almost always better known ; 
their affinities have been more systematically studied ; and it 
may be safely affirmed that no explanation of the origin of the 
fauna of a country can be sound which does not also explain, 
or at least harmonize with, the distribution and relations of its 
flora. 

The relations of the flora of New Zealand to that of Australia 
have long formed an insoluble enigma for botanists. Sir Joseph 
Hooker, in his most instructive and masterly essay on the flora 
of Australia, says, " Under whatever aspect I regard the flora 
of Australia and of New Zealand, I find all attempts to theorize 
on the possible causes of their community of feature frustrated 
by anomalies in distribution such as I believe no two other simi- 
larly situated countries in the globe present. Everywhere else 
I recognize a parallelism or harmony in the main common feat- 
ures of contiguous floras, which conveys the impression of their 
generic affinity, at least, being affected by migration from centres 

29 



450 ISLAND LIFE. [Paiit IL 

of dispersion in one of tliem, or in some adjacent country. In 
this case it is widely different. Kcgarding the question from 
the Australian point of view, it is impossible, in the present state 
of science, to reconcile the fact of Acacia, Eucalyptus, Casuarina, 
Callitris, etc., being absent in New Zealand with any theory of 
transoceanic migration that may be adopted to explain the pres- 
ence of other Australian plants in New Zealand ; and it is very 
diflScult to conceive of a time or of conditions that could ex- 
plain these anomalies, except by going back to epochs when the 
prevalent botanical as well as geographical features of each were 
widely different from what they are now. On the other hand, 
if I regard the question from the New Zealand point of view, I 
find such broad features of resemblance, and so many connect- 
ing-links that afford irresistible evidence of a close botanical 
connection, that I cannot abandon the conviction that these great 
differences will present the least dif