the malay archipelago-1-第4节

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h　we　possess　any　record；　been　also　slowly　changing。

It　is　not　now　necessary　to　say　anything　about　how　either　of　those　changes　took　place；　as　to　that；　opinions　may　differ；　but　as　to　the　fact　that　the　changes　themselves　have　occurred；　from　the　earliest　geological　ages　down　to　the　present　day；　and　are　still　going　on；　there　is　no　difference　of　opinion。　Every　successive　stratum　of　sedimentary　rock；　sand；　or　gravel；　is　a　proof　that　changes　of　level　have　taken　place；　and　the　different　species　of　animals　and　plants；　whose　remains　are　found　in　these　deposits；　prove　that　corresponding　changes　did　occur　in　the　organic　world。

Taking；　therefore；　these　two　series　of　changes　for　granted；　most　of　the　present　peculiarities　and　anomalies　in　the　distribution　of　species　may　be　directly　traced　to　them。　In　our　own　islands；　with　a　very　few　trifling　exceptions；　every　quadruped；　bird；　reptile；　insect；　and　plant；　is　found　also　on　the　adjacent　continent。　In　the　small　islands　of　Sardinia　and　Corsica；　there　are　some　quadrupeds　and　insects；　and　many　plants；　quite　peculiar。　In　Ceylon；　more　closely　connected　to　India　than　Britain　is　to　Europe；　many　animals　and　plants　are　different　from　those　found　in　India；　and　peculiar　to　the　island。　In　the　Galapagos　Islands；　almost　every　indigenous　living　thing　is　peculiar　to　them；　though　closely　resembling　other　kinds　found　in　the　nearest　parts　of　the　American　continent。

Most　naturalists　now　admit　that　these　facts　can　only　be　explained　by　the　greater　or　less　lapse　of　time　since　the　islands　were　upraised　from　beneath　the　ocean；　or　were　separated　from　the　nearest　land；　and　this　will　be　generally　（though　not　always）　indicated　by　the　depth　of　the　intervening　sea。　The　enormous　thickness　of　many　marine　deposits　through　wide　areas　shows　that　subsidence　has　often　continued　（with　intermitting　periods　of　repose）　during　epochs　of　immense　duration。　The　depth　of　sea　produced　by　such　subsidence　will　therefore　generally　be　a　measure　of　time；　and　in　like　manner；　the　change　which　organic　forms　have　undergone　is　a　measure　of　time。　When　we　make　proper　allowance　for　the　continued　introduction　of　new　animals　and　plants　from　surrounding　countries　by　those　natural　means　of　dispersal　which　have　been　so　well　explained　by　Sir　Charles　Lyell　and　Mr。　Darwin；　it　is　remarkable　how　closely　these　two　measures　correspond。　Britain　is　separated　from　the　continent　by　a　very　shallow　sea；　and　only　in　a　very　few　cases　have　our　animals　or　plants　begun　to　show　a　difference　from　the　corresponding　continental　species。　Corsica　and　Sardinia；　divided　from　Italy　by　a　much　deeper　sea；　present　a　much　greater　difference　in　their　organic　forms。　Cuba；　separated　from　Yucatan　by　a　wider　and　deeper　strait；　differs　more　markedly；　so　that　most　of　its　productions　are　of　distinct　and　peculiar　species；　while　Madagascar；　divided　from　Africa　by　a　deep　channel　three　hundred　miles　wide；　possesses　so　many　peculiar　features　as　to　indicate　separation　at　a　very　remote　antiquity；　or　even　to　render　it　doubtful　whether　the　two　countries　have　ever　been　absolutely　united。

Returning　now　to　the　Malay　Archipelago；　we　find　that　all　the　wide　expanse　of　sea　which　divides　Java；　Sumatra；　and　Borneo　from　each　other；　and　from　Malacca　and　Siam；　is　so　shallow　that　ships　can　anchor　in　any　part　of　it；　since　it　rarely　exceeds　forty　fathoms　in　depth；　and　if　we　go　as　far　as　the　line　of　a　hundred　fathoms；　we　shall　include　the　Philippine　Islands　and　Bali；　east　of　Java。　If；　therefore；　these　islands　have　been　separated　from　each　other　and　the　continent　by　subsidence　of　the　intervening　tracts　of　land；　we　should　conclude　that　the　separation　has　been　comparatively　recent；　since　the　depth　to　which　the　land　has　subsided　is　so　small。　It　is　also　to　be　remarked　that　the　great　chain　of　active　volcanoes　in　Sumatra　and　Java　furnishes　us　with　a　sufficient　cause　for　such　subsidence；　since　the　enormous　masses　of　matter　they　have　thrown　out　would　take　away　the　foundations　of　the　surrounding　district；　and　this　may　be　the　true　explanation　of　the　often…noticed　fact　that　volcanoes　and　volcanic　chains　are　always　near　the　sea。　The　subsidence　they　produce　around　them　will；　in　time；　make　a　sea；　if　one　does　not　already　exist。

But；　it　is　when　we　examine　the　zoology　of　these　countries　that　we　find　what　we　most　requireevidence　of　a　very　striking　character　that　these　great　islands　must　have　once　formed　a　part　of　the　continent；　and　could　only　have　been　separated　at　a　very　recent　geological　epoch。　The　elephant　and　tapir　of　Sumatra　and　Borneo；　the　rhinoceros　of　Sumatra　and　the　allied　species　of　Java；　the　wild　cattle　of　Borneo　and　the　kind　long　supposed　to　be　peculiar　to　Java；　are　now　all　known　to　inhabit　some　part　or　other　of　Southern　Asia。　None　of　these　large　animals　could　possibly　have　passed　over　the　arms　of　the　sea　which　now　separate　these　countries；　and　their　presence　plainly　indicates　that　a　land　communication　must　have　existed　since　the　origin　of　the　species。　Among　the　smaller　mammals；　a　considerable　portion　are　common　to　each　island　and　the　continent；　but　the　vast　physical　changes　that　must　have　occurred　during　the　breaking　up　and　subsidence　of　such　extensive　regions　have　led　to　the　extinction　of　some　in　one　or　more　of　the　islands；　and　in　some　cases　there　seems　also　to　have　been　time　for　a　change　of　species　to　have　taken　place。　Birds　and　insects　illustrate　the　same　view；　for　every　family　and　almost　every　genus　of　these　groups　found　in　any　of　the　islands　occurs　also　on　the　Asiatic　continent；　and　in　a　great　number　of　cases　the　species　are　exactly　identical。　Birds　offer　us　one　of　the　best　means　of　determining　the　law　of　distribution；　for　though　at　first　sight　it　would　appear　that　the　watery　boundaries　which　keep　out　the　land　quadrupeds　could　be　easily　passed　over　by　birds；　yet　practically　it　is　not　so；　for　if　we　leave　out　the　aquatic　tribes　which　are　preeminently　wanderers；　it　is　found　that　the　others　（and　especially　the　Passeres；　or　true　perching…birds；　which　form　the　vast　majority）　are　generally　as　strictly　limited　by　straits　and　arms　of　the　sea　as　are　quadrupeds　themselves。　As　an　instance；　among　the　islands　of　which　I　am　now　speaking；　it　is　a　remarkable　fact　that　Java　possesses　numerous　birds　which　never　pass　over　to　Sumatra；　though　they　are　separated　by　a　strait　only　fifteen　miles　wide；　and　with　islands　in　mid…channel。　Java；　in　fact；　possesses　more　birds　and　insects　peculiar　to　itself　than　either　Sumatra　or　Borneo；　and　this　would　indicate　that　it　was　earliest　separated　from　the　continent；　next　in　organic　individuality　is　Borneo；　while　Sumatra　is　so　nearly　identical　in　all　its　animal　forms　with　the　peninsula　of　Malacca；　that　we　may　safely　conclude　it　to　have　been　the　most　recently　dismembered　island。

The　general　result　therefore；　at　which　we　arrive；　is　that　the　great　islands　of　Java；　Sumatra；　and　Borneo　resemble　in　their　natural　productions　the　adjacent　parts　of　the　continent；　almost　as　much　as　such　widely…separated　districts　could　be　expected　to　do　even　if　they　still　formed　a　part　of　Asia；　and　this　close　resemblance；　joined　with　the　fact　of　the　wide　extent　of　sea　which　separates　them　being　so　uniformly　and　remarkably　shallow；　and　lastly；　the　existence　of　the　extensive　range　of　volcanoes　in　Sumatra　and　Java；　which　have　poured　out　vast　quantities　of　subterranean　matter　and　have　built　up　extensive　plateaux　and　lofty　mountain　ranges；　thus　furnishing　a　vera　causa　for　a　parallel　line　of　subsidenceall　lead　irresistibly　to　the　conclusion　that　at　a　very　recent　geological　epoch；　the　continent　of　Asia　extended　far　beyond　its　present　limits　in　a　south…　easterly　direction；　including　the　islands　of　Java；　Sumatra；　and　Borneo；　and　probably　reaching　as　far　as　the　present　100…fathom　line　of　soundings。

The　Philippine　Islands　agree　in　many　respects　with　Asia　and　the　other　islands；　but　present　some　anomalies；　which　seem　to　indicate　that　they　were　separated　at　an　earlier　period；　and　have　since　been　subject　to　many　revolutions　in　their　physical　geography。

Turning　our　attention　now　to　the　remaining　portion　of　the　Archipelago；　we　shall　find　that　all　the　islands　from　Celebes　and　Lombock　eastward　exhibit　almost　as　close　a　resemblance　to　Australia　and　New　Guinea　as　the　Western　Islands　do　to　Asia。　It　is　well　known　that　the　natural　productions　of　Australia　differ　from　those　of　Asia　more　than　those　of　any　of　the　four　ancient　quarters　of　the　world　differ　from　each　other。　Australia；　in　fact；　stands　alone：　it　possesses　no　apes　or　monkeys；　no　cats　or　tigers；　wolves；　bears；　or　hyenas；　no　deer　or　antelopes；　sheep　or　oxen；　no　elephant；　horse；　squirrel；　or　rabbit；　none；　in　short；　of　those　familiar　types　of　quadruped　which　are　met　with　in　every　other　part　of　the　world。　Instead　of　these；　it　has　Marsupials　only：　kangaroos　and　opossums；　wombats　and　the　duckbilled　Platypus。　In　birds　it　is　almost　as　peculiar。　It　has　no　woodpeckers　and　no　pheasantsfamilies　which　exist　in　every　other　part　of　the　world；　but　instead　of　them　it　has　the　mound…making　brush…turkeys；　the　honeysuckers；　the　cockatoos；　and　the　brush…tongued　lories；　which　are　found　nowhere　else　upon　the　globe。　All　these　striking　peculiarities　are　found　also　in　those　islands　which　form　the　Austro…Malayan　division　of　the　Archipelago。

The　great　contrast　between　the　two　divisions　of　the　Archipelago　is　nowhere　so　abr