the malay archipelago-1-第34节

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prevented　the　passage　of　birds　from　one　island　to　another；　so　that　out　of　at　least　three　hundred　and　fifty　land　birds　inhabiting　Java　and　Borneo；　not　more　than　ten　have　passed　eastward　into　Celebes。　Yet　the　Straits　of　Macassar　are　not　nearly　so　wide　as　the　Java　sea；　and　at　least　a　hundred　species　are　common　to　Borneo　and　Java。

I　will　now　give　two　examples　to　show　how　a　knowledge　of　the　distribution　of　animals　may　reveal　unsuspected　facts　in　the　past　history　of　the　earth。　At　the　eastern　extremity　of　Sumatra；　and　separated　from　it　by　a　strait　about　fifteen　miles　wide；　is　the　small　rocky　island　of　Banca；　celebrated　for　its　tin　mines。　One　of　the　Dutch　residents　there　sent　some　collections　of　birds　and　animals　to　Leyden；　and　among　them　were　found　several　species　distinct　from　those　of　the　adjacent　coast　of　Sumatra。　One　of　these　was　a　squirrel　（Sciurus　bangkanus）；　closely　allied　to　three　other　species　inhabiting　respectively　the　Malay　peninsula；　Sumatra；　and　Borneo；　but　quite　as　distinct　from　them　all　as　they　are　from　each　other。　There　were　also　two　new　ground　thrushes　of　the　genus　Pitta；　closely　allied　to；　but　quite　distinct　from；　two　other　species　inhabiting　both　Sumatra　and　Borneo；　and　which　did　not　perceptibly　differ　in　these　large　and　widely　separated　islands。　This　is　just　as　if　the　Isle　of　Man　possessed　a　peculiar　species　of　thrush　and　blackbird；　distinct　from　the　birds　which　are　common　to　England　and　Ireland。

These　curious　facts　would　indicate　that　Banca　may　have　existed　as　a　distinct　island　even　longer　than　Sumatra　and　Borneo；　and　there　are　some　geological　and　geographical　facts　which　render　this　not　so　improbable　as　it　would　at　first　seem　to　be。　Although　on　the　map　Banca　appears　so　close　to　Sumatra；　this　does　not　arise　from　its　having　been　recently　separated　from　it；　for　the　adjacent　district　of　Palembang　is　new　land；　being　a　great　alluvial　swamp　formed　by　torrents　from　the　mountains　a　hundred　miles　distant。

Banca；　on　the　other　hand；　agrees　with　Malacca；　Singapore；　and　the　intervening　island　of　Lingen；　in　being　formed　of　granite　and　laterite；　and　these　have　all　most　likely　once　formed　an　extension　of　the　Malay　peninsula。　As　the　rivers　of　Borneo　and　Sumatra　have　been　for　ages　filling　up　the　intervening　sea；　we　may　be　sure　that　its　depth　has　recently　been　greater；　and　it　is　very　probable　that　those　large　islands　were　never　directly　connected　with　each　other　except　through　the　Malay　peninsula。　At　that　period　the　same　species　of　squirrel　and　Pitta　may　have　inhabited　all　these　countries；　but　when　the　subterranean　disturbances　occurred　which　led　to　the　elevation　of　the　volcanoes　of　Sumatra；　the　small　island　of　Banca　may　have　been　separated　first；　and　its　productions　being　thus　isolated　might　be　gradually　modified　before　the　separation　of　the　larger　islands　had　been　completed。

As　the　southern　part　of　Sumatra　extended　eastward　and　formed　the　narrow　straits　of　Banca；　many　birds　and　insects　and　some　Mammalia　would　cross　from　one　to　the　other；　and　thus　produce　a　general　similarity　of　productions；　while　a　few　of　the　older　inhabitants　remained；　to　reveal　by　their　distinct　forms；　their　different　origin。　Unless　we　suppose　some　such　changes　in　physical　geography　to　have　occurred；　the　presence　of　peculiar　species　of　birds　and　mammals　in　such　an　island　as　Banca　is　a　hopeless　puzzle；　and　I　think　I　have　shown　that　the　changes　required　are　by　no　means　so　improbable　as　a　mere　glance　at　the　map　would　lead　us　to　suppose。

For　our　next　example　let　us　take　the　great　islands　of　Sumatra　and　Java。　These　approach　so　closely　together；　and　the　chain　of　volcanoes　that　runs　through　them　gives　such　an　air　of　unity　to　the　two；　that　the　idea　of　their　having　been　recently　dissevered　is　immediately　suggested。　The　natives　of　Java；　however；　go　further　than　this；　for　they　actually　have　a　tradition　of　the　catastrophe　which　broke　them　asunder；　and　fix　its　date　at　not　much　more　than　a　thousand　years　ago。　It　becomes　interesting；　therefore；　to　see　what　support　is　given　to　this　view　by　the　comparison　of　their　animal　productions。

The　Mammalia　have　not　been　collected　with　sufficient　completeness　in　both　islands　to　make　a　general　comparison　of　much　value；　and　so　many　species　have　been　obtained　only　as　live　specimens　in　captivity；　that　their　locality　has　often　been　erroneously　given；　the　island　in　which　they　were　obtained　being　substituted　for　that　from　which　they　originally　came。　Taking　into　consideration　only　those　whose　distribution　is　more　accurately　known；　we　learn　that　Sumatra　is；　in　a　zoological　sense；　more　neatly　related　to　Borneo　than　it　is　to　Java。　The　great　man…like　apes；　the　elephant；　the　tapir；　and　the　Malay　bear；　are　all　common　to　the　two　former　countries；　while　they　are　absent　from　the　latter。　Of　the　three　long…tailed　monkeys　（Semnopithecus）　inhabiting　Sumatra；　one　extends　into　Borneo；　but　the　two　species　of　Java　are　both　peculiar　to　it。　So　also　the　great　Malay　deer　（Rusa　equina）；　and　the　small　Tragulus　kanchil；　are　common　to　Sumatra　and　Borneo；　but　do　not　extend　into　Java；　where　they　are　replaced　by　Tragulas　javanicus。　The　tiger；　it　is　true；　is　found　in　Sumatra　and　Java；　but　not　in　Borneo。　But　as　this　animal　is　known　to　swim　well；　it　may　have　found　its　way　across　the　Straits　of　Sunda；　or　it　may　have　inhabited　Java　before　it　was　separated　from　the　mainland；　and　from　some　unknown　cause　have　ceased　to　exist　in　Borneo。

In　Ornithology　there　is　a　little　uncertainty　owing　to　the　birds　of　Java　and　Sumatra　being　much　better　known　than　those　of　Borneo；　but　the　ancient　separation　of　Java　as　an　island　is　well　exhibited　by　the　large　number　of　its　species　which　are　not　found　in　any　of　the　other　islands。　It　possesses　no　less　than　seven　pigeons　peculiar　to　itself；　while　Sumatra　has　only　one。　Of　its　two　parrots　one　extends　into　Borneo；　but　neither　into　Sumatra。　Of　the　fifteen　species　of　woodpeckers　inhabiting　Sumatra　only　four　reach　Java；　while　eight　of　them　are　found　in　Borneo　and　twelve　in　the　Malay　peninsula。　The　two　Trogons　found　in　Java　are　peculiar　to　it；　while　of　those　inhabiting　Sumatra　at　least　two　extend　to　Malacca　and　one　to　Borneo。　There　are　a　very　large　number　of　birds；　such　as　the　great　Argus　pheasant；　the　fire…backed　and　ocellated　pheasants；　the　crested　partridge　（Rollulus　coronatus）；　the　small　Malacca　parrot　（Psittinus　incertus）；　the　great　helmeted　hornbill　（Buceroturus　galeatus）；　the　pheasant　ground…cuckoo　（Carpococcyx　radiatus）；　the　rose…crested　bee…eater　（Nyctiornis　amicta）；　the　great　gaper　（Corydon　sumatranus）；　and　the　green…　crested　gaper　（Calyptomena　viridis）；　and　many　others；　which　are　common　to　Malacca；　Sumatra；　and　Borneo；　but　are　entirely　absent　from　Java。　On　the　other　hand　we　have　the　peacock；　the　green　jungle　cock；　two　blue　ground　thrushes　（Arrenga　cyanea　and　Myophonus　flavirostris）；　the　fine　pink…headed　dove　（Ptilonopus　porphyreus）；　three　broad…tailed　ground　pigeons　（Macropygia）；　and　many　other　interesting　birds；　which　are　found　nowhere　in　the　Archipelago　out　of　Java。

Insects　furnish　us　with　similar　facts　wherever　sufficient　data　are　to　be　had；　but　owing　to　the　abundant　collections　that　have　been　made　in　Java；　an　unfair　preponderance　may　be　given　to　that　island。　This　does　not；　however；　seem　to　be　the　case　with　the　true　Papilionidae　or　swallow…tailed　butterflies；　whose　large　size　and　gorgeous　colouring　has　led　to　their　being　collected　more　frequently　than　other　insects。　Twenty…seven　species　are　known　from　Java；　twenty…nine　from　Borneo；　and　only　twenty…one　from　Sumatra。　Four　are　entirely　confined　to　Java；　while　only　two　are　peculiar　to　Borneo　and　one　to　Sumatra。　The　isolation　of　Java　will；　however；　be　best　shown　by　grouping　the　islands　in　pairs；　and　indicating　the　number　of　species　common　to　each　pair。　Thus：


Borneo　　。　。　　。　　。　。　29　species　Sumatra　。　。　　。　　。　。　21　　do。　　　　20　species　common　to　both　islands。

Borneo　　。　。　　。　　。　。　29　　do。　　　Java　。　　。　。　　。　　。　。　27　　do。　　　　20　　　　do。　　　　do。

Sumatra　。　。　　。　　。　。　21　　do。　Java　。　　。　。　　。　　。　。　27　　do。　　　　11　　　　do。　　　　do。

Making　some　allowance　for　our　imperfect　knowledge　of　the　Sumatran　species；　we　see　that　Java　is　more　isolated　from　the　two　larger　islands　than　they　are　from　each　other；　thus　entirely　confirming　the　results　given　by　the　distribution　of　birds　and　Mammalia；　and　rendering　it　almost　certain　that　the　last…named　island　was　the　first　to　be　completely　separated　from　the　Asiatic　continent；　and　that　the　native　tradition　of　its　having　been　recently　separated　from　Sumatra　is　entirely　without　foundation。

We　are　now　able　to　trace　out　with　some　probability　the　course　of　events。　Beginning　at　the　time　when　the　whole　of　the　Java　sea；　the　Gulf　of　Siam；　and　the　Straits　of　Malacca　were　dry　land；　forming　with　Borneo；　Sumatra；　and　Java；　a　vast　southern　prolongation　of　the　Asiatic　continent；　the　first　movement　would　be　the　sinking　down　of　the　Java　sea；　and　the　Straits　of　Sunda；　consequent　on　the　activity　of　the　Javanese　volcanoes　along　the　southern　extremity　of　the　land；　and　leading　to　the　complete　separation　of　that　island。　As　the　volcanic　belt　of　Java　and　Sumatra　increased　in　activity；　more　and　more　of　the　land　was　submerged；　until　first　Borneo；　and　afterwards　Sumatra；　became　entirely　severed。　Since　the　epoch　of　the　first　disturbance；　several　distinct　elevations　and　depressions　may　have　taken　pl