the malay archipelago-1- 第4部分

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　abruptly　exhibited　as　on　passing　from　the　island　of　Bali　to　that　of　Lombock；　where　the　two　regions　are　in　closest　proximity。　In　Bali　we　have　barbets；　fruit…thrushes；　and　woodpeckers；　on　passing　over　to　Lombock　these　are　seen　no　more；　but　we　have　abundance　of　cockatoos；　honeysuckers；　and　brush…　turkeys；　which　are　equally　unknown　in　Bali；　or　any　island　further　west。　＇I　was　informed；　however；　that　there　were　a　few　cockatoos　at　one　spot　on　the　west　of　Bali；　showing　that　the　intermingling　of　the　productions　of　these　islands　is　now　going　on。＇　The　strait　is　here　fifteen　miles　wide；　so　that　we　may　pass　in　two　hours　from　one　great　division　of　the　earth　to　another；　differing　as　essentially　in　their　animal　life　as　Europe　does　from　America。　If　we　travel　from　Java　or　Borneo　to　Celebes　or　the　Moluccas；　the　difference　is　still　more　striking。　In　the　first；　the　forests　abound　in　monkeys　of　many　kinds；　wild　cats；　deer；　civets；　and　otters；　and　numerous　varieties　of　squirrels　are　constantly　met　with。　In　the　latter　none　of　these　occur；　but　the　prehensile…　tailed　Cuscus　is　almost　the　only　terrestrial　mammal　seen；　except　wild　pigs；　which　are　found　in　all　the　islands；　and　deer　（which　have　probably　been　recently　introduced）　in　Celebes　and　the　Moluccas。　The　birds　which　are　most　abundant　in　the　Western　Islands　are　woodpeckers；　barbets；　trogons；　fruit…thrushes；　and　leaf…thrushes；　they　are　seen　daily；　and　form　the　great　ornithological　features　of　the　country。　In　the　Eastern　Islands　these　are　absolutely　unknown；　honeysuckers　and　small　lories　being　the　most　common　birds；　so　that　the　naturalist　feels　himself　in　a　new　world；　and　can　hardly　realize　that　he　has　passed　from　the　one　region　to　the　other　in　a　few　days；　without　ever　being　out　of　sight　of　land。

The　inference　that　we　must　draw　from　these　facts　is；　undoubtedly；　that　the　whole　of　the　islands　eastwards　beyond　Java　and　Borneo　do　essentially　form　a　part　of　a　former　Australian　or　Pacific　continent；　although　some　of　them　may　never　have　been　actually　joined　to　it。　This　continent　must　have　been　broken　up　not　only　before　the　Western　Islands　were　separated　from　Asia；　but　probably　before　the　extreme　southeastern　portion　of　Asia　was　raised　above　the　waters　of　the　ocean；　for　a　great　part　of　the　land　of　Borneo　and　Java　is　known　to　be　geologically　of　quite　recent　formation；　while　the　very　great　difference　of　species；　and　in　many　cases　of　genera　also；　between　the　productions　of　the　Eastern　Malay　Islands　and　Australia；　as　well　as　the　great　depth　of　the　sea　now　separating　them；　all　point　to　a　comparatively　long　period　of　isolation。

It　is　interesting　to　observe　among　the　islands　themselves　how　a　shallow　sea　always　intimates　a　recent　land　connexion。　The　Aru　Islands；　Mysol；　and　Waigiou；　as　well　as　Jobie；　agree　with　New　Guinea　in　their　species　of　mammalia　and　birds　much　more　closely　than　they　do　with　the　Moluccas；　and　we　find　that　they　are　all　united　to　New　Guinea　by　a　shallow　sea。　In　fact；　the　100…fathom　line　round　New　Guinea　marks　out　accurately　the　range　of　the　true　Paradise　birds。

It　is　further　to　be　notedand　this　is　a　very　interesting　point　in　connection　with　theories　of　the　dependence　of　special　forms　of　life　on　external　conditionsthat　this　division　of　the　Archipelago　into　two　regions　characterised　by　a　striking　diversity　in　their　natural　productions　does　not　in　any　way　correspond　to　the　main　physical　or　climatal　divisions　of　the　surface。　The　great　volcanic　chain　runs　through　both　parts；　and　appears　to　produce　no　effect　in　assimilating　their　productions。　Borneo　closely　resembles　New　Guinea　not　only　in　its　vast　size　and　its　freedom　from　volcanoes；　but　in　its　variety　of　geological　structure；　its　uniformity　of　climate；　and　the　general　aspect　of　the　forest　vegetation　that　clothes　its　surface。　The　Moluccas　are　the　counterpart　of　the　Philippines　in　their　volcanic　structure；　their　extreme　fertility；　their　luxuriant　forests；　and　their　frequent　earthquakes；　and　Bali　with　the　east　end　of　Java　has　a　climate　almost　as　dry　and　a　soil　almost　as　arid　as　that　of　Timor。　Yet　between　these　corresponding　groups　of　islands；