ThesetwospeciesofAmblyrhynchusagree,asIhavealreadystated,intheirgeneralstructure,andinmanyoftheirhabits。Neitherhavethatrapidmovement,socharacteristicofthegeneraLacertaandIguana。Theyarebothherbivorous,althoughthekindofvegetationonwhichtheyfeedissoverydifferent。Mr。Bellhasgiventhenametothegenusfromtheshortnessofthesnout:indeed,theformofthemouthmayalmostbecomparedtothatofthetortoise:oneisledtosupposethatthisisanadaptationtotheirherbivorousappetites。Itisveryinterestingthustofindawell-characterizedgenus,havingitsmarineandterrestrialspecies,belongingtosoconfinedaportionoftheworld。Theaquaticspeciesisbyfarthemostremarkable,becauseitistheonlyexistinglizardwhichlivesonmarinevegetableproductions。AsIatfirstobserved,theseislandsarenotsoremarkableforthenumberofthespeciesofreptiles,asforthatoftheindividuals,whenwerememberthewell-beatenpathsmadebythethousandsofhugetortoises——themanyturtles——thegreatwarrensoftheterrestrialAmblyrhynchus——andthegroupsofthemarinespeciesbaskingonthecoast-rocksofeveryisland——wemustadmitthatthereisnootherquarteroftheworldwherethisOrderreplacestheherbivorousmammaliainsoextraordinaryamanner。ThegeologistonhearingthiswillprobablyreferbackinhismindtotheSecondaryepochs,whenlizards,someherbivorous,somecarnivorous,andofdimensionscomparableonlywithourexistingwhales,swarmedonthelandandinthesea。Itis,therefore,worthyofhisobservation,thatthisarchipelago,insteadofpossessingahumidclimateandrankvegetation,cannotbeconsideredotherwisethanextremelyarid,and,foranequatorialregion,remarkablytemperate。
Tofinishwiththezoology:thefifteenkindsofsea-fishwhichIprocuredhereareallnewspecies;theybelongtotwelvegenera,allwidelydistributed,withtheexceptionofPrionotus,ofwhichthefourpreviouslyknownspeciesliveontheeasternsideofAmerica。Ofland-shellsIcollectedsixteenkindsandtwomarkedvarieties,ofwhich,withtheexceptionofoneHelixfoundatTahiti,allarepeculiartothisarchipelago:asinglefresh-watershellPaludinaiscommontoTahitiandVanDiemen’sLand。Mr。Cuming,beforeourvoyageprocuredhereninetyspeciesofsea-shells,andthisdoesnotincludeseveralspeciesnotyetspecificallyexamined,ofTrochus,Turbo,Monodonta,andNassa。Hehasbeenkindenoughtogivemethefollowinginterestingresults:Oftheninetyshells,nolessthanforty-sevenareunknownelsewhere——awonderfulfact,consideringhowwidelydistributedsea-shellsgenerallyare。Oftheforty-threeshellsfoundinotherpartsoftheworld,twenty-fiveinhabitthewesterncoastofAmerica,andoftheseeightaredistinguishableasvarieties;theremainingeighteenincludingonevarietywerefoundbyMr。CumingintheLowArchipelago,andsomeofthemalsoatthePhilippines。ThisfactofshellsfromislandsinthecentralpartsofthePacificoccurringhere,deservesnotice,fornotonesinglesea-shellisknowntobecommontotheislandsofthatoceanandtothewestcoastofAmerica。Thespaceofopensearunningnorthandsouthoffthewestcoast,separatestwoquitedistinctconchologicalprovinces;
butattheGalapagosArchipelagowehaveahalting-place,wheremanynewformshavebeencreated,andwhitherthesetwogreatconchologicalprovinceshaveeachsentupseveralcolonists。TheAmericanprovincehasalsosenthererepresentativespecies;forthereisaGalapageianspeciesofMonoceros,agenusonlyfoundonthewestcoastofAmerica;andthereareGalapageianspeciesofFissurellaandCancellaria,generacommononthewestcoast,butnotfoundasIaminformedbyMr。CuminginthecentralislandsofthePacific。Ontheotherhand,thereareGalapageianspeciesofOnisciaandStylifer,generacommontotheWestIndiesandtotheChineseandIndianseas,butnotfoundeitheronthewestcoastofAmericaorinthecentralPacific。Imayhereadd,thatafterthecomparisonbyMessrs。CumingandHindsofabout2000shellsfromtheeasternandwesterncoastsofAmerica,onlyonesingleshellwasfoundincommon,namely,thePurpurapatula,whichinhabitstheWestIndies,thecoastofPanama,andtheGalapagos。
Wehave,therefore,inthisquarteroftheworld,threegreatconchologicalsea-provinces,quitedistinct,thoughsurprisinglyneareachother,beingseparatedbylongnorthandsouthspaceseitheroflandorofopensea。
Itookgreatpainsincollectingtheinsects,butexceptingTierradelFuego,Ineversawinthisrespectsopooracountry。EvenintheupperanddampregionIprocuredveryfew,exceptingsomeminuteDipteraandHymenoptera,mostlyofcommonmundaneforms。Asbeforeremarked,theinsects,foratropicalregion,areofverysmallsizeanddullcolours。OfbeetlesIcollectedtwenty-fivespeciesexcludingaDermestesandCorynetesimported,whereverashiptouches;ofthese,twobelongtotheHarpalidae,twototheHydrophilidae,ninetothreefamiliesoftheHeteromera,andtheremainingtwelvetoasmanydifferentfamilies。ThiscircumstanceofinsectsandImayaddplants,wherefewinnumber,belongingtomanydifferentfamilies,is,Ibelieve,verygeneral。Mr。Waterhouse,whohaspublished[4]anaccountoftheinsectsofthisarchipelago,andtowhomIamindebtedfortheabovedetails,informsmethatthereareseveralnewgenera:andthatofthegeneranotnew,oneortwoareAmerican,andtherestofmundanedistribution。Withtheexceptionofawood-feedingApate,andofoneorprobablytwowater-beetlesfromtheAmericancontinent,allthespeciesappeartobenew。
Thebotanyofthisgroupisfullyasinterestingasthezoology。Dr。
J。Hookerwillsoonpublishinthe“LinneanTransactions“afullaccountoftheFlora,andIammuchindebtedtohimforthefollowingdetails。
Offloweringplantsthereare,asfarasatpresentisknown,185species,and40cryptogamicspecies,makingaltogether225;ofthisnumberIwasfortunateenoughtobringhome193。Ofthefloweringplants,100arenewspecies,andareprobablyconfinedtothisarchipelago。Dr。Hookerconceivesthat,oftheplantsnotsoconfined,atleast10speciesfoundnearthecultivatedgroundatCharlesIsland,havebeenimported。Itis,Ithink,surprisingthatmoreAmericanspecieshavenotbeenintroducednaturally,consideringthatthedistanceisonlybetween500and600milesfromthecontinent,andthataccordingtoCollnet,p。58drift-wood,bamboos,canes,andthenutsofapalm,areoftenwashedonthesouth-easternshores。
Theproportionof100floweringplantsoutof183or175excludingtheimportedweedsbeingnew,issufficient,Iconceive,tomaketheGalapagosArchipelagoadistinctbotanicalprovince;butthisFloraisnotnearlysopeculiarasthatofSt。Helena,nor,asIaminformedbyDr。Hooker,ofJuanFernandez。ThepeculiarityoftheGalapageianFloraisbestshownincertainfamilies;——thusthereare21speciesofCompositae,ofwhich20arepeculiartothisarchipelago;thesebelongtotwelvegenera,andofthesegeneranolessthantenareconfinedtothearchipelago!Dr。HookerinformsmethattheFlorahasanundoubtedlyWesternAmericancharacter;
norcanhedetectinitanyaffinitywiththatofthePacific。If,therefore,weexcepttheeighteenmarine,theonefresh-water,andoneland-shell,whichhaveapparentlycomehereascolonistsfromthecentralislandsofthePacific,andlikewisetheonedistinctPacificspeciesoftheGalapageiangroupoffinches,weseethatthisarchipelago,thoughstandinginthePacificOcean,iszoologicallypartofAmerica。
IfthischaracterwereowingmerelytoimmigrantsfromAmerica,therewouldbelittleremarkableinit;butweseethatavastmajorityofallthelandanimals,andthatmorethanhalfofthefloweringplants,areaboriginalproductionsItwasmoststrikingtobesurroundedbynewbirds,newreptiles,newshells,newinsects,newplants,andyetbyinnumerabletriflingdetailsofstructure,andevenbythetonesofvoiceandplumageofthebirds,tohavethetemperateplainsofPatagonia,orratherthehotdrydesertsofNorthernChile,vividlybroughtbeforemyeyes。Why,onthesesmallpointsofland,whichwithinalategeologicalperiodmusthavebeencoveredbytheocean,whichareformedbybasalticlava,andthereforedifferingeologicalcharacterfromtheAmericancontinent,andwhichareplacedunderapeculiarclimate,——whyweretheiraboriginalinhabitants,associated,Imayadd,indifferentproportionsbothinkindandnumberfromthoseonthecontinent,andthereforeactingoneachotherinadifferentmanner——whyweretheycreatedonAmericantypesoforganization?
ItisprobablethattheislandsoftheCapedeVerdgroupresemble,inalltheirphysicalconditions,farmorecloselytheGalapagosIslands,thantheselatterphysicallyresemblethecoastofAmerica,yettheaboriginalinhabitantsofthetwogroupsaretotallyunlike;thoseoftheCapedeVerdIslandsbearingtheimpressofAfrica,astheinhabitantsoftheGalapagosArchipelagoarestampedwiththatofAmericaIhavenotasyetnoticedbyfarthemostremarkablefeatureinthenaturalhistoryofthisarchipelago;itis,thatthedifferentislandstoaconsiderableextentareinhabitedbyadifferentsetofbeings。MyattentionwasfirstcalledtothisfactbytheVice-Governor,Mr。Lawson,declaringthatthetortoisesdifferedfromthedifferentislands,andthathecouldwithcertaintytellfromwhichislandanyonewasbrought。Ididnotforsometimepaysufficientattentiontothisstatement,andIhadalreadypartiallymingledtogetherthecollectionsfromtwooftheislands。
Ineverdreamedthatislands,about50or60milesapart,andmostoftheminsightofeachother,formedofpreciselythesamerocks,placedunderaquitesimilarclimate,risingtoanearlyequalheight,wouldhavebeendifferentlytenanted;butweshallsoonseethatthisisthecase。Itisthefateofmostvoyagers,nosoonertodiscoverwhatismostinterestinginanylocality,thantheyarehurriedfromit;butIought,perhaps,tobethankfulthatIobtainedsufficientmaterialstoestablishthismostremarkablefactinthedistributionoforganicbeings。
Theinhabitants,asIhavesaid,statethattheycandistinguishthetortoisesfromthedifferentislands;andthattheydiffernotonlyinsize,butinothercharacters。CaptainPorterhasdescribed[5]thosefromCharlesandfromthenearestislandtoit,namely,HoodIsland,ashavingtheirshellsinfrontthickandturneduplikeaSpanishsaddle,whilstthetortoisesfromJamesIslandarerounder,blacker,andhaveabettertastewhencooked。M。Bibron,moreover,informsmethathehasseenwhatheconsiderstwodistinctspeciesoftortoisefromtheGalapagos,buthedoesnotknowfromwhichislands。ThespecimensthatIbroughtfromthreeislandswereyoungones:andprobablyowingtothiscauseneitherMr。Graynormyselfcouldfindinthemanyspecificdifferences。IhaveremarkedthatthemarineAmblyrhynchuswaslargeratAlbemarleIslandthanelsewhere;andM。Bibroninformsmethathehasseentwodistinctaquaticspeciesofthisgenus;sothatthedifferentislandsprobablyhavetheirrepresentativespeciesorracesoftheAmblyrhynchus,aswellasofthetortoise。Myattentionwasfirstthoroughlyaroused,bycomparingtogetherthenumerousspecimens,shotbymyselfandseveralotherpartiesonboard,ofthemocking-thrushes,when,tomyastonishment,IdiscoveredthatallthosefromCharlesIslandbelongedtoonespeciesMimustrifasciatus
allfromAlbemarleIslandtoM。parvulus;andallfromJamesandChathamIslandsbetweenwhichtwootherislandsaresituated,asconnectinglinks
belongedtoM。melanotis。Thesetwolatterspeciesarecloselyallied,andwouldbysomeornithologistsbeconsideredasonlywell-markedracesorvarieties;buttheMimustrifasciatusisverydistinct。Unfortunatelymostofthespecimensofthefinchtribeweremingledtogether;butIhavestrongreasonstosuspectthatsomeofthespeciesofthesub-groupGeospizaareconfinedtoseparateislands。IfthedifferentislandshavetheirrepresentativesofGeospiza,itmayhelptoexplainthesingularlylargenumberofthespeciesofthissub-groupinthisonesmallarchipelago,andasaprobableconsequenceoftheirnumbers,theperfectlygraduatedseriesinthesizeoftheirbeaks。Twospeciesofthesub-groupCactornis,andtwooftheCamarhynchus,wereprocuredinthearchipelago;andofthenumerousspecimensofthesetwosub-groupsshotbyfourcollectorsatJamesIsland,allwerefoundtobelongtoonespeciesofeach;whereasthenumerousspecimensshoteitheronChathamorCharlesIslandforthetwosetsweremingledtogetherallbelongedtothetwootherspecies:hencewemayfeelalmostsurethattheseislandspossesstheirrespectivespeciesofthesetwosub-groups。
Inland-shellsthislawofdistributiondoesnotappeartoholdgood。
Inmyverysmallcollectionofinsects,Mr。Waterhouseremarks,thatofthosewhichwereticketedwiththeirlocality,notonewascommontoanytwooftheislands。
IfwenowturntotheFlora,weshallfindtheaboriginalplantsofthedifferentislandswonderfullydifferent。IgiveallthefollowingresultsonthehighauthorityofmyfriendDr。J。Hooker。ImaypremisethatI
indiscriminatelycollectedeverythinginfloweronthedifferentislands,andfortunatelykeptmycollectionsseparate。Toomuchconfidence,however,mustnotbeplacedintheproportionalresults,asthesmallcollectionsbroughthomebysomeothernaturaliststhoughinsomerespectsconfirmingtheresults,plainlyshowthatmuchremainstobedoneinthebotanyofthisgroup:theLeguminosae,moreover,hasasyetbeenonlyapproximatelyworkedout:——NumberofSpeciesconfinedtotheNumberofNumberofGalapagosspeciesspeciesNumberArchipelagoTotalfoundinconfinedconfinedbutfoundNameNumberothertothetotheonmoreofofpartsofGalapagosonethantheIslandSpeciestheworldArchipelagoislandoneislandJames