第66章

类别:其他 作者:Charles Darwin字数:5250更新时间:18/12/21 17:23:57
Theinhabitantsbelievethattheseanimalsareabsolutelydeaf;certainlytheydonotoverhearapersonwalkingclosebehindthem。Iwasalwaysamusedwhenovertakingoneofthesegreatmonsters,asitwasquietlypacingalong,toseehowsuddenly,theinstantIpassed,itwoulddrawinitsheadandlegs,andutteringadeephissfalltothegroundwithaheavysound,asifstruckdead。Ifrequentlygotontheirbacks,andthengivingafewrapsonthehinderpartoftheirshells,theywouldriseupandwalkaway;—— butIfounditverydifficulttokeepmybalance。Thefleshofthisanimalislargelyemployed,bothfreshandsalted;andabeautifullyclearoilispreparedfromthefat。Whenatortoiseiscaught,themanmakesaslitintheskinnearitstail,soastoseeinsideitsbody,whetherthefatunderthedorsalplateisthick。Ifitisnot,theanimalisliberatedanditissaidtorecoversoonfromthisstrangeoperation。Inordertosecurethetortoise,itisnotsufficienttoturnthemliketurtle,fortheyareoftenabletogetontheirlegsagain。 TherecanbelittledoubtthatthistortoiseisanaboriginalinhabitantoftheGalapagos;foritisfoundonall,ornearlyall,theislands,evenonsomeofthesmalleroneswherethereisnowater;haditbeenanimportedspecies,thiswouldhardlyhavebeenthecaseinagroupwhichhasbeensolittlefrequented。Moreover,theoldBucaniersfoundthistortoiseingreaternumberseventhanatpresent:WoodandRogersalso,in1708,saythatitistheopinionoftheSpaniards,thatitisfoundnowhereelseinthisquarteroftheworld。Itisnowwidelydistributed;butitmaybequestionedwhetheritisinanyotherplaceanaboriginal。ThebonesofatortoiseatMauritius,associatedwiththoseoftheextinctDodo,havegenerallybeenconsideredasbelongingtothistortoise;ifthishadbeenso,undoubtedlyitmusthavebeenthereindigenous;butM。Bibroninformsmethathebelievesthatitwasdistinct,asthespeciesnowlivingtherecertainlyis。 TheAmblyrhynchus,aremarkablegenusoflizards,isconfinedtothisarchipelago;therearetwospecies,resembling[picture] eachotheringeneralform,onebeingterrestrialandtheotheraquatic。 Thislatterspecies(A。cristatus)wasfirstcharacterizedbyMr。Bell,whowellforesaw,fromitsshort,broadhead,andstrongclawsofequallength,thatitshabitsoflifewouldturnoutverypeculiar,anddifferentfromthoseofitsnearestally,theIguana。Itisextremelycommononalltheislandsthroughoutthegroup,andlivesexclusivelyontherockysea-beaches,beingneverfound,atleastIneversawone,eventenyardsin-shore。Itisahideous-lookingcreature,ofadirtyblackcolour,stupid,andsluggishinitsmovements。Theusuallengthofafull-grownoneisaboutayard,buttherearesomeevenfourfeetlong;alargeoneweighedtwentypounds: ontheislandofAlbemarletheyseemtogrowtoagreatersizethanelsewhere。 Theirtailsareflattenedsideways,andallfourfeetpartiallywebbed。 Theyareoccasionallyseensomehundredyardsfromtheshore,swimmingabout;andCaptainCollnett,inhisVoyagesays,“Theygotoseainherdsa-fishing,andsunthemselvesontherocks;andmaybecalledalligatorsinminiature。”Itmustnot,however,besupposedthattheyliveonfish。 Wheninthewaterthislizardswimswithperfecteaseandquickness,byaserpentinemovementofitsbodyandflattenedtail——thelegsbeingmotionlessandcloselycollapsedonitssides。Aseamanonboardsankone,withaheavyweightattachedtoit,thinkingthustokillitdirectly; butwhen,anhourafterwards,hedrewuptheline,itwasquiteactive。 Theirlimbsandstrongclawsareadmirablyadaptedforcrawlingovertheruggedandfissuredmassesoflava,whicheverywhereformthecoast。Insuchsituations,agroupofsixorsevenofthesehideousreptilesmayoftentimesbeseenontheblackrocks,afewfeetabovethesurf,baskinginthesunwithoutstretchedlegs。 Iopenedthestomachsofseveral,andfoundthemlargelydistendedwithmincedsea-weed(Ulvae),whichgrowsinthinfoliaceousexpansionsofabrightgreenoradullredcolour。Idonotrecollecthavingobservedthissea-weedinanyquantityonthetidalrocks;andIhavereasontobelieveitgrowsatthebottomofthesea,atsomelittledistancefromthecoast。 Ifsuchbethecase,theobjectoftheseanimalsoccasionallygoingouttoseaisexplained。Thestomachcontainednothingbutthesea-weed。Mr。 Baynoe,however,foundapieceofcrabinone;butthismighthavegotinaccidentally,inthesamemannerasIhaveseenacaterpillar,inthemidstofsomelichen,inthepaunchofatortoise。Theintestineswerelarge,asinotherherbivorousanimals。Thenatureofthislizard’sfood,aswellasthestructureofitstailandfeet,andthefactofitshavingbeenseenvoluntarilyswimmingoutatsea,absolutelyproveitsaquatichabits;yetthereisinthisrespectonestrangeanomaly,namely,thatwhenfrighteneditwillnotenterthewater。Henceitiseasytodrivetheselizardsdowntoanylittlepointoverhangingthesea,wheretheywillsoonerallowapersontocatchholdoftheirtailsthanjumpintothewater。Theydonotseemtohaveanynotionofbiting;butwhenmuchfrightenedtheysquirtadropoffluidfromeachnostril。IthrewoneseveraltimesasfarasIcould,intoadeeppoolleftbytheretiringtide;butitinvariablyreturnedinadirectlinetothespotwhereIstood。Itswamnearthebottom,withaverygracefulandrapidmovement,andoccasionallyaideditselfovertheunevengroundwithitsfeet。Assoonasitarrivedneartheedge,butstillbeingunderwater,ittriedtoconcealitselfinthetuftsofsea-weed,oritenteredsomecrevice。Assoonasitthoughtthedangerwaspast,itcrawledoutonthedryrocks,andshuffledawayasquicklyasitcould。Iseveraltimescaughtthissamelizard,bydrivingitdowntoapoint,andthoughpossessedofsuchperfectpowersofdivingandswimming,nothingwouldinduceittoenterthewater;andasoftenasIthrewitin,itreturnedinthemannerabovedescribed。Perhapsthissingularpieceofapparentstupiditymaybeaccountedforbythecircumstance,thatthisreptilehasnoenemywhateveronshore,whereasatseaitmustoftenfallapreytothenumeroussharks。Hence,probably,urgedbyafixedandhereditaryinstinctthattheshoreisitsplaceofsafety,whatevertheemergencymaybe,ittheretakesrefuge。 Duringourvisit(inOctober),Isawextremelyfewsmallindividualsofthisspecies,andnoneIshouldthinkunderayearold。Fromthiscircumstanceitseemsprobablethatthebreedingseasonhadnotthencommenced。Iaskedseveraloftheinhabitantsiftheyknewwhereitlaiditseggs:theysaidthattheyknewnothingofitspropagation,althoughwellacquaintedwiththeeggsofthelandkind——afact,consideringhowverycommonthislizardis,notalittleextraordinary。 Wewillnowturntotheterrestrialspecies(A。Demarlii),witharoundtail,andtoeswithoutwebs。Thislizard,insteadofbeingfoundliketheotheronalltheislands,isconfinedtothecentralpartofthearchipelago,namelytoAlbemarle,James,Barrington,andIndefatigableislands。Tothesouthward,inCharles,Hood,andChathamislands,andtothenorthward,inTowers,Bindloes,andAbingdon,Ineithersawnorheardofany。Itwouldappearasifithadbeencreatedinthecentreofthearchipelago,andthencehadbeendispersedonlytoacertaindistance。Someoftheselizardsinhabitthehighanddamppartsoftheislands,buttheyaremuchmorenumerousinthelowerandsteriledistrictsnearthecoast。Icannotgiveamoreforcibleproofoftheirnumbers,thanbystatingthatwhenwewereleftatJamesIsland,wecouldnotforsometimefindaspotfreefromtheirburrowsonwhichtopitchoursingletent。Liketheirbrothersthesea-kind,theyareuglyanimals,ofayellowishorangebeneath,andofabrownishredcolourabove:fromtheirlowfacialangletheyhaveasingularlystupidappearance。Theyare,perhaps,ofaratherlesssizethanthemarinespecies;butseveralofthemweighedbetweentenandfifteenpounds。Intheirmovementstheyarelazyandhalftorpid。Whennotfrightened,theyslowlycrawlalongwiththeirtailsandbelliesdraggingontheground。 Theyoftenstop,anddozeforaminuteortwo,withclosedeyesandhindlegsspreadoutontheparchedsoil。 Theyinhabitburrows,whichtheysometimesmakebetweenfragmentsoflava,butmoregenerallyonlevelpatchesofthesoftsandstone-liketuff。 Theholesdonotappeartobeverydeep,andtheyenterthegroundatasmallangle;sothatwhenwalkingovertheselizard-warrens,thesoilisconstantlygivingway,muchtotheannoyanceofthetiredwalker。Thisanimal,whenmakingitsburrow,worksalternatelytheoppositesidesofitsbody。Onefrontlegforashorttimescratchesupthesoil,andthrowsittowardsthehindfoot,whichiswellplacedsoastoheaveitbeyondthemouthofthehole。Thatsideofthebodybeingtired,theothertakesupthetask,andsoonalternately。Iwatchedoneforalongtime,tillhalfitsbodywasburied;Ithenwalkedupandpulleditbythetail,atthisitwasgreatlyastonished,andsoonshuffleduptoseewhatwasthematter;andthenstaredmeintheface,asmuchastosay,“Whatmadeyoupullmytail?” Theyfeedbyday,anddonotwanderfarfromtheirburrows;iffrightened,theyrushtothemwithamostawkwardgait。Exceptwhenrunningdownhill,theycannotmoveveryfast,apparentlyfromthelateralpositionoftheirlegs。Theyarenotatalltimorous:whenattentivelywatchinganyone,theycurltheirtails,and,raisingthemselvesontheirfrontlegs,nodtheirheadsvertically,withaquickmovement,andtrytolookveryfierce; butinrealitytheyarenotatallso:ifonejuststampsontheground,downgotheirtails,andofftheyshuffleasquicklyastheycan。Ihavefrequentlyobservedsmallfly-eatinglizards,whenwatchinganything,nodtheirheadsinpreciselythesamemanner;butIdonotatallknowforwhatpurpose。IfthisAmblyrhynchusisheldandplaguedwithastick,itwillbiteitveryseverely;butIcaughtmanybythetail,andtheynevertriedtobiteme。Iftwoareplacedonthegroundandheldtogether,theywillfight,andbiteeachothertillbloodisdrawn。 Theindividuals,andtheyarethegreaternumber,whichinhabitthelowercountry,canscarcelytasteadropofwaterthroughouttheyear; buttheyconsumemuchofthesucculentcactus,thebranchesofwhichareoccasionallybrokenoffbythewind。Iseveraltimesthrewapiecetotwoorthreeofthemwhentogether;anditwasamusingenoughtoseethemtryingtoseizeandcarryitawayintheirmouths,likesomanyhungrydogswithabone。Theyeatverydeliberately,butdonotchewtheirfood。Thelittlebirdsareawarehowharmlessthesecreaturesare:Ihaveseenoneofthethick-billedfinchespickingatoneendofapieceofcactus(whichismuchrelishedbyalltheanimalsofthelowerregion),whilstalizardwaseatingattheotherend;andafterwardsthelittlebirdwiththeutmostindifferencehoppedonthebackofthereptile。 Iopenedthestomachsofseveral,andfoundthemfullofvegetablefibresandleavesofdifferenttrees,especiallyofanacacia。Intheupperregiontheylivechieflyontheacidandastringentberriesoftheguayavita,underwhichtreesIhaveseentheselizardsandthehugetortoisesfeedingtogether。Toobtaintheacacia-leavestheycrawlupthelowstuntedtrees; anditisnotuncommontoseeapairquietlybrowsing,whilstseatedonabranchseveralfeetabovetheground。Theselizards,whencooked,yieldawhitemeat,whichislikedbythosewhosestomachssoaraboveallprejudices。 HumboldthasremarkedthatinintertropicalSouthAmerica,alllizardswhichinhabitdryregionsareesteemeddelicaciesforthetable。Theinhabitantsstatethatthosewhichinhabittheupperdamppartsdrinkwater,butthattheothersdonot,likethetortoises,travelupforitfromthelowersterilecountry。Atthetimeofourvisit,thefemaleshadwithintheirbodiesnumerous,large,elongatedeggs,whichtheylayintheirburrows: theinhabitantsseekthemforfood。