4degs。S。tolat。32degs。S。，maybedescribedasadesert；onthiswesterncoast，northwardoflat。4degs。S。，wherethetrade-windlosesitsregularity，andheavytorrentsofrainfallperiodically，theshoresofthePacific，soutterlydesertinPeru，assumenearCapeBlancothecharacterofluxuriancesocelebratedatGuyaquilandPanama。Henceinthesouthernandnorthernpartsofthecontinent，theforestanddesertlandsoccupyreversedpositionswithrespecttotheCordillera，andthesepositionsareapparentlydeterminedbythedirectionoftheprevalentwinds。Inthemiddleofthecontinentthereisabroadintermediateband，includingcentralChileandtheprovincesofLaPlata，wheretherain-bringingwindshavenottopassoverloftymountains，andwherethelandisneitheradesertnorcoveredbyforests。
Buteventherule，ifconfinedtoSouthAmerica，oftreesflourishingonlyinaclimaterenderedhumidbyrain-bearingwinds，hasastronglymarkedexceptioninthecaseoftheFalklandIslands。Theseislands，situatedinthesamelatitudewithTierradelFuegoandonlybetweentwoandthreehundredmilesdistantfromit，havinganearlysimilarclimate，withageologicalformationalmostidentical，withfavourablesituationsandthesamekindofpeatysoil，yetcanboastoffewplantsdeservingeventhetitleofbushes；whilstinTierradelFuegoitisimpossibletofindanacreoflandnotcoveredbythedensestforest。Inthiscase，boththedirectionoftheheavygalesofwindandofthecurrentsoftheseaarefavourabletothetransportofseedsfromTierradelFuego，asisshownbythecanoesandtrunksoftreesdriftedfromthatcountry，andfrequentlythrownontheshoresoftheWesternFalkland。Henceperhapsitis，thattherearemanyplantsincommontothetwocountriesbutwithrespecttothetreesofTierradelFuego，evenattemptsmadetotransplantthemhavefailed。
DuringourstayatMaldonadoIcollectedseveralquadrupeds，eightykindsofbirds，andmanyreptiles，includingninespeciesofsnakes。Oftheindigenousmammalia，theonlyonenowleftofanysize，whichiscommon，istheCervuscampestris。Thisdeerisexceedinglyabundant，ofteninsmallherds，throughoutthecountriesborderingthePlataandinNorthernPatagonia。
Ifapersoncrawlingclosealongtheground，slowlyadvancestowardsaherd，thedeerfrequently，outofcuriosity，approachtoreconnoitrehim。
Ihavebythismeans，killedfromonespot，threeoutofthesameherd。
Althoughsotameandinquisitive，yetwhenapproachedonhorseback，theyareexceedinglywary。Inthiscountrynobodygoesonfoot，andthedeerknowsmanasitsenemyonlywhenheismountedandarmedwiththebolas。
AtBahiaBlanca，arecentestablishmentinNorthernPatagonia，Iwassurprisedtofindhowlittlethedeercaredforthenoiseofagun：onedayIfiredtentimesfromwithineightyyardsatoneanimal；anditwasmuchmorestartledattheballcuttingupthegroundthanatthereportoftherifle。
Mypowderbeingexhausted，Iwasobligedtogetuptomyshameasasportsmanbeitspoken，thoughwellabletokillbirdsonthewingandhallootillthedeerranaway。
Themostcuriousfactwithrespecttothisanimal，istheoverpoweringlystrongandoffensiveodourwhichproceedsfromthebuck。Itisquiteindescribable：
severaltimeswhilstskinningthespecimenwhichisnowmountedattheZoologicalMuseum，Iwasalmostovercomebynausea。Itieduptheskininasilkpocket-handkerchief，andsocarriedithome：thishandkerchief，afterbeingwellwashed，Icontinuallyused，anditwasofcourseasrepeatedlywashed；yeteverytime，foraspaceofoneyearandsevenmonths，whenfirstunfolded，Idistinctlyperceivedtheodour。Thisappearsanastonishinginstanceofthepermanenceofsomematter，whichneverthelessinitsnaturemustbemostsubtileandvolatile。Frequently，whenpassingatthedistanceofhalfamiletoleewardofaherd，Ihaveperceivedthewholeairtaintedwiththeeffluvium。Ibelievethesmellfromthebuckismostpowerfulattheperiodwhenitshornsareperfect，orfreefromthehairyskin。
Wheninthisstatethemeatis，ofcourse，quiteuneatable；buttheGauchosassert，thatifburiedforsometimeinfreshearth，thetaintisremoved。
IhavesomewherereadthattheislandersinthenorthofScotlandtreattherankcarcassesofthefish-eatingbirdsinthesamemanner。
TheorderRodentiaishereverynumerousinspecies：ofmicealoneI
obtainednolessthaneightkinds。[4]Thelargestgnawinganimalintheworld，theHydrochaeruscapybarathewater-hog，isherealsocommon。OnewhichIshotatMonteVideoweighedninety-eightpounds：itslengthfromtheendofthesnouttothestump-liketail，wasthreefeettwoinches；anditsgirththreefeeteight。ThesegreatRodentsoccasionallyfrequenttheislandsinthemouthofthePlata，wherethewaterisquitesalt，butarefarmoreabundantonthebordersoffresh-waterlakesandrivers。NearMaldonadothreeorfourgenerallylivetogether。
Inthedaytimetheyeitherlieamongtheaquaticplants，oropenlyfeedontheturfplain。[5]Whenviewedatadistance，fromtheirmannerofwalkingandcolourtheyresemblepigs：butwhenseatedontheirhaunches，andattentivelywatchinganyobjectwithoneeye，theyreassumetheappearanceoftheircongeners，caviesandrabbits。Boththefrontandsideviewoftheirheadhasquitealudicrousaspect，fromthegreatdepthoftheirjaw。Theseanimals，atMaldonado，wereverytame；
bycautiouslywalking，Iapproachedwithinthreeyardsoffouroldones。
Thistamenessmayprobablybeaccountedfor，bytheJaguarhavingbeenbanishedforsomeyears，andbytheGauchonotthinkingitworthhiswhiletohuntthem。AsIapproachednearerandnearertheyfrequentlymadetheirpeculiarnoise，whichisalowabruptgrunt，nothavingmuchactualsound，butratherarisingfromthesuddenexpulsionofair：theonlynoiseIknowatalllikeit，isthefirsthoarsebarkofalargedog。Havingwatchedthefourfromalmostwithinarm’slengthandtheymeforseveralminutes，theyrushedintothewateratfullgallopwiththegreatestimpetuosity，andemittedatthesametimetheirbark。Afterdivingashortdistancetheycameagaintothesurface，butonlyjustshowedtheupperpartoftheirheads。Whenthefemaleisswimminginthewater，andhasyoungones，theyaresaidtositonherback。Theseanimalsareeasilykilledinnumbers；
buttheirskinsareoftriflingvalue，andthemeatisveryindifferent。
OntheislandsintheRioParanatheyareexceedinglyabundant，andaffordtheordinarypreytotheJaguar。
TheTucutucoCtenomysBrasiliensisisacurioussmallanimal，whichmaybebrieflydescribedasaGnawer，withthehabitsofamole。Itisextremelynumerousinsomepartsofthecountry，butitisdifficulttobeprocured，andnever，Ibelieve，comesoutoftheground。Itthrowsupatthemouthofitsburrowshillocksofearthlikethoseofthemole，butsmaller。Considerabletractsofcountryaresocompletelyunderminedbytheseanimals，thathorsesinpassingover，sinkabovetheirfetlocks。
Thetucutucosappear，toacertaindegree，tobegregarious：themanwhoprocuredthespecimensformehadcaughtsixtogether，andhesaidthiswasacommonoccurrence。Theyarenocturnalintheirhabits；andtheirprincipalfoodistherootsofplants，whicharetheobjectoftheirextensiveandsuperficialburrows。Thisanimalisuniversallyknownbyaverypeculiarnoisewhichitmakeswhenbeneaththeground。Aperson，thefirsttimehehearsit，ismuchsurprised；foritisnoteasytotellwhenceitcomes，norisitpossibletoguesswhatkindofcreatureuttersit。Thenoiseconsistsinashort，butnotrough，nasalgrunt，whichismonotonouslyrepeatedaboutfourtimesinquicksuccession：[6]thenameTucutucoisgiveninimitationofthesound。Wherethisanimalisabundant，itmaybeheardatalltimesoftheday，andsometimesdirectlybeneathone’sfeet。Whenkeptinaroom，thetucutucosmovebothslowlyandclumsily，whichappearsowingtotheoutwardactionoftheirhindlegs；
andtheyarequiteincapable，fromthesocketofthethigh-bonenothavingacertainligament，ofjumpingeventhesmallestverticalheight。Theyareverystupidinmakinganyattempttoescape；whenangryorfrightenedtheyutterthetucutuco。OfthoseIkeptaliveseveral，eventhefirstday，becamequitetame，notattemptingtobiteortorunaway；otherswerealittlewilder。
Themanwhocaughtthemassertedthatverymanyareinvariablyfoundblind。AspecimenwhichIpreservedinspiritswasinthisstate；Mr。Reidconsidersittobetheeffectofinflammationinthenictitatingmembrane。
WhentheanimalwasaliveIplacedmyfingerwithinhalfaninchofitshead，andnottheslightestnoticewastaken：itmadeitsway，however，abouttheroomnearlyaswellastheothers。Consideringthestrictlysubterraneanhabitsofthetucutuco，theblindness，thoughsocommon，cannotbeaveryseriousevil；yetitappearsstrangethatanyanimalshouldpossessanorganfrequentlysubjecttobeinjured。Lamarckwouldhavebeendelightedwiththisfact，hadheknownit，whenspeculating[7]probablywithmoretruththanusualwithhimonthegradually_acquired_
blindnessoftheAsphalax，aGnawerlivingunderground，andoftheProteus，areptilelivingindarkcavernsfilledwithwater；inbothofwhichanimalstheeyeisinanalmostrudimentarystate，andiscoveredbyatendinousmembraneandskin。Inthecommonmoletheeyeisextraordinarilysmallbutperfect，thoughmanyanatomistsdoubtwhetheritisconnectedwiththetrueopticnerve；itsvisionmustcertainlybeimperfect，thoughprobablyusefultotheanimalwhenitleavesitsburrow。Inthetucutuco，whichIbelievenevercomestothesurfaceoftheground，theeyeisratherlarger，butoftenrenderedblindanduseless，thoughwithoutapparentlycausinganyinconveniencetotheanimal；nodoubtLamarckwouldhavesaidthatthetucutucoisnowpassingintothestateoftheAsphalaxandProteus。
Birdsofmanykindsareextremelyabundantontheundulating，grassyplainsaroundMaldonado。ThereareseveralspeciesofafamilyalliedinstructureandmannerstoourStarling：oneoftheseMolothrusnigerisremarkablefromitshabits。Severalmayoftenbeseenstandingtogetherontbebackofacoworhorse；andwhileperchedonahedge，plumingthemselvesinthesun，theysometimesattempttosing，orrathertohiss；thenoisebeingverypeculiar，resemblingthatofbubblesofairpassingrapidlyfromasmallorificeunderwater，soastoproduceanacutesound。AccordingtoAzara，thisbird，likethecuckoo，depositsitseggsinotherbirds’
nests。Iwasseveraltimestoldbythecountrypeoplethattherecertainlyissomebirdhavingthishabit；andmyassistantincollecting，whoisaveryaccurateperson，foundanestofthesparrowofthiscountryZonotrichiamatutina，withoneegginitlargerthantheothers，andofadifferentcolourandshape。InNorthAmericathereisanotherspeciesofMolothrusM。pecoris，whichhasasimilarcuckoo-likehabit，andwhichismostcloselyalliedineveryrespecttothespeciesfromthePlata，eveninsuchtriflingpeculiaritiesasstandingonthebacksofcattle；itdiffersonlyinbeingalittlesmaller，andinitsplumageandeggsbeingofaslightlydifferentshadeofcolour。Thiscloseagreementinstructureandhabits，inrepresentativespeciescomingfromoppositequartersofagreatcontinent，alwaysstrikesoneasinteresting，thoughofcommonoccurrence。
Mr。Swainsonhaswellremarked，[8]thatwiththeexceptionoftheMolothruspecoris，towhichmustbeaddedtheM。niger，thecuckoosaretheonlybirdswhichcanbecalledtrulyparasitical；namely，suchas“fastenthemselves，asitwere，onanotherlivinganimal，whoseanimalheatbringstheiryoungintolife，whosefoodtheyliveupon，andwhosedeathwouldcausetheirsduringtheperiodofinfancy。”Itisremarkablethatsomeofthespecies，butnotall，bothoftheCuckooandMolothrus，shouldagreeinthisonestrangehabitoftheirparasiticalpropagation，whilstopposedtoeachotherinalmosteveryotherhabit：themolothrus，likeourstarling，iseminentlysociable，andlivesontheopenplainswithoutartordisguise：thecuckoo，aseveryoneknows，isasingularlyshybird；itfrequentsthemostretiredthickets，andfeedsonfruitandcaterpillars。Instructurealsothesetwogeneraarewidelyremovedfromeachother。Manytheories，evenphrenologicaltheories，havebeenadvancedtoexplaintheoriginofthecuckoolayingitseggsinotherbirds’nests。