Withtheincreasedordiminishedlengthofthebeakthelengthoftheslitformingtheexternalorificeofthenostrilsvaries，butnotindueproportion，for，takingtherock—pigeonasthestandard，theorificeinaShort—facedTumblerwasnotshortenedindueproportionwithitsveryshortbeak。Ontheotherhand（andthiscouldnothavebeenanticipated），theorificeinthreeEnglishCarriers，intheBagadottenCarrier，andinaRunt（pigeoncygne），waslongerbyabovethetenthofaninchthanwouldfollowfromthelengthofthebeakproportionallywiththatoftherock—pigeon。InoneCarriertheorificeofthenostrilswasthriceaslongasintherock—
　　pigeon，thoughinbodyandlengthofbeakthisbirdwasnotnearlydoublethesizeoftherock—pigeon。Thisgreatlyincreasedlengthoftheorificeofthenostrilsseemstostandpartlyincorrelationwiththeenlargementofthewattledskinontheuppermandibleandoverthenostrils;andthisisacharacterwhichisselectedbyfanciers。Soagain，thebroad，naked，andwattledskinroundtheeyesofCarriersandBarbsisaselectedcharacter;andinobviouscorrelationwiththis，theeyelids，measuredlongitudinally，areproportionallymorethandoublethelengthofthoseoftherock—pigeon。
　　Thegreatdifference（seefigure27）inthecurvatureofthelowerjawintherock—pigeon，theTumbler，andBagadottenCarrier，standsinobviousrelationtothecurvatureoftheupperjaw，andmoreespeciallytotheangleformedbythemaxillo—jugalarchwiththepremaxillarybones。ButinCarriers，Runts，andBarbsthesingularreflexionoftheuppermarginofthemiddlepartofthelowerjaw（seefigure25）isnotstrictlycorrelatedwiththewidthordivergence（asmaybeclearlyseeninfigure26）ofthepremaxillarybones，butwiththebreadthofthehornyandsoftpartsoftheuppermandible，whicharealwaysoverlappedbytheedgesofthelowermandible。
　　InPouters，theelongationofthebodyisaselectedcharacter，andtheribs，aswehaveseen，havegenerallybecomeverybroad，withtheseventhpairfurnishedwithprocesses;thesacralandcaudalvertebraehavebeenaugmentedinnumber;thesternumhaslikewiseincreasedinlength（butnotinthedepthofthecrest）by。4ofaninchmorethanwouldfollowfromthegreaterbulkofthebodyincomparisonwiththatoftherock—pigeon。InFantails，thelengthandnumberofthecaudalvertebraehaveincreased。
　　Hence，duringthegradualprogressofvariationandselection，theinternalbonyframeworkandtheexternalshapeofthebodyhavebeen，toacertainextent，modifiedinacorrelatedmanner。
　　Althoughthewingsandtailoftenvaryinlengthindependentlyofeachother，itisscarcelypossibletodoubtthattheygenerallytendtobecomeelongatedorshortenedincorrelation。ThisiswellseeninJacobins，andstillmoreplainlyinRunts，somevarietiesofwhichhavetheirwingsandtailofgreatlength，whilstothershavebothveryshort。WithJacobins，theremarkablelengthofthetailandwing—feathersisnotacharacterwhichisintentionallyselectedbyfanciers;butfanciershavebeentryingforcenturies，atleastsincetheyear1600，toincreasethelengthofthereversedfeathersontheneck，sothatthehoodmaymorecompletelyenclosethehead;anditmaybesuspectedthattheincreasedlengthofthewingandtail—feathersstandincorrelationwiththeincreasedlengthoftheneck—
　　feathers。Short—facedTumblershaveshortwingsinnearlydueproportionwiththereducedsizeoftheirbodies;butitisremarkable，seeingthatthenumberoftheprimarywing—feathersisaconstantcharacterinmostbirds，thattheseTumblersgenerallyhaveonlynineinsteadoftenprimaries。Ihavemyselfobservedthisineightbirds;andtheOriginalColumbarianSociety（5/37。J。M。Eaton’Treatise’edition1858page78。）
　　reducedthestandardforBald—headTumblersfromtentoninewhiteflight—
　　feathers，thinkingitunfairthatabirdwhichhadonlyninefeathersshouldbedisqualifiedforaprizebecauseithadnottenWHITEflight—
　　feathers。Ontheotherhand，inCarriersandRunts，whichhavelargebodiesandlongwings，elevenprimaryfeathershaveoccasionallybeenobserved。
　　Mr。Tegetmeierhasinformedmeofacuriousandinexplicablecaseofcorrelation，namely，thatyoungpigeonsofallbreedswhichwhenmaturebecomewhite，yellow，silver（i。e。，extremelypaleblue），ordun—coloured，arebornalmostnaked;whereaspigeonsofothercoloursarebornwell—
　　clothedwithdown。Mr。Esquilant，however，hasobservedthatyoungdunCarriersarenotsobareasyoungdunBarbsandTumblers。Mr。Tegetmeierhasseentwoyoungbirdsinthesamenest，producedfromdifferentlycolouredparents，whichdifferedgreatlyinthedegreetowhichtheywereatfirstclothedwithdown。
　　Ihaveobservedanothercaseofcorrelationwhichatfirstsightappearsquiteinexplicable，butonwhich，asweshallseeinafuturechapter，somelightcanbethrownbythelawofhomologouspartsvaryinginthesamemanner。Thecaseis，that，whenthefeetaremuchfeathered，therootsofthefeathersareconnectedbyawebofskin，andapparentlyincorrelationwiththisthetwooutertoesbecomeconnectedforaconsiderablespacebyskin。IhaveobservedthisinverymanyspecimensofPouters，Trumpeters，Swallows，Roller—tumblers（likewiseobservedinthisbreedbyMr。Brent），andinalesserdegreeinotherfeather—footedpigeons。
　　Thefeetofthesmallerandlargerbreedsareofcoursemuchsmallerorlargerthanthoseoftherock—pigeon;butthescutellaeorscalescoveringthetoesandtarsihavenotonlydecreasedorincreasedinsize，butlikewiseinnumber。Togiveasingleinstance，IhavecountedeightscutellaeonthehindtoeofaRunt，andonlyfiveonthatofaShort—facedTumbler。Withbirdsinastateofnaturethenumberofthescutellaeonthefeetisusuallyaconstantcharacter。Thelengthofthefeetandthelengthofthebeakapparentlystandincorrelation;butasdisuseapparentlyhasaffectedthesizeofthefeet，thiscasemaycomeunderthefollowingdiscussion。
　　ONTHEEFFECTSOFDISUSE。
　　Inthefollowingdiscussionontherelativeproportionsofthefeet，sternum，furculum，scapulae，andwings，Imaypremise，inordertogivesomeconfidencetothereader，thatallmymeasurementsweremadeinthesamemanner，andthattheyweremadewithouttheleastintentionofapplyingthemtothefollowingpurpose。
　　[TABLE5。I。
　　PIGEONSWITHTHEIRBEAKSGENERALLYSHORTERTHANTHATOFTHEROCK—PIGEON，PROPORTIONALLYTOTHESIZEOFTHEIRBODIES。
　　Column1。NameofBreed。
　　Column2。ActuallengthofFeet（inches）。
　　Column3。Differencebetweenactualandcalculatedlengthoffeet，inproportiontolengthoffeetandsizeofbodyintheRock—pigeon。
　　Column3a。Tooshortby（inches）。
　　Column3b。Toolongby（inches）。
　　1。2。3a。3b。
　　Wildrock—pigeon（meanmeasurement）。2。02
　　Short—facedTumbler，bald—head。1。570。11……
　　Short—facedTumbler，almond。1。600。16……
　　Tumbler，redmagpie。1。750。19……
　　Tumbler，redcommon（bystandardtoendoftail）。1。850。07……
　　Tumbler，commonbald—head。1。850。18……
　　Tumbler，roller。1。800。06……
　　Turbit。1。750。17……
　　Turbit。1。800。01……
　　Turbit。1。840。15……
　　Jacobin。1。900。02……
　　Trumpeter，white。2。020。06……
　　Trumpeter，mottled。1。950。18……
　　Fantail（bystandardtoendoftail）。1。850。15……
　　Fantail（bystandardtoendoftail）。1。950。15……
　　Fantailcrestedvar。Ditto。1。950。00。0
　　IndianFrill—backDitto。1。8O0。19……
　　EnglishFrill—back。2。100。03……
　　Nun。1。820。02……
　　Laugher。1。650。16……
　　Barb。2。000。03……
　　Barb。2。00……
　　0。03
　　Spot。1。900。02……
　　Spot。1。900。07……
　　Swallow，red。1。850。18……
　　Swallow，blue。2。00……
　　0。03
　　Pouter。2。42……
　　0。11
　　Pouter，German。2。30……
　　0。09
　　BussorahCarrier。2。17……
　　0。09
　　Numberofspecimens。28225
　　Imeasuredmostofthebirdswhichcameintomypossession，fromthefeatheredBASEofthebeak（thelengthofbeakitselfbeingsovariable）totheendofthetail，andtotheoil—gland，butunfortunately（exceptinafewcases）nottotherootofthetail;Imeasuredeachbirdfromtheextremetiptotipofwing;andthelengthoftheterminalfoldedpartofthewing，fromtheextremityoftheprimariestothejointoftheradius。I
　　measuredthefeetwithouttheclaws，fromtheendofthemiddletoetotheendofthehindtoe;andthetarsusandmiddletoetogether。Ihavetakenineverycasethemeanmeasurementoftwowildrock—pigeonsfromtheShetlandIslands，asthestandardofcomparison。Thefollowingtableshowstheactuallengthofthefeetineachbird;andthedifferencebetweenthelengthwhichthefeetoughttohavehadaccordingtothesizeofbodyofeach，incomparisonwiththesizeofbodyandlengthoffeetoftherock—
　　pigeon，calculated（withafewspecifiedexceptions）bythestandardofthelengthofthebodyfromthebaseofthebeaktotheoil—gland。Ihavepreferredthisstandard，owingtothevariabilityofthelengthoftail。
　　ButIhavemadesimilarcalculations，takingasthestandardthelengthfromtiptotipofwing，andlikewiseinmostcasesfromthebaseofthebeaktotheendofthetail;andtheresulthasalwaysbeencloselysimilar。Togiveanexample:thefirstbirdinthetable，beingaShort—
　　facedTumbler，ismuchsmallerthantherock—pigeon，andwouldnaturallyhaveshorterfeet;butitisfoundoncalculationtohavefeettooshortby。11ofaninch，incomparisonwiththefeetoftherock—pigeon，relativelytothesizeofthebodyinthesetwobirds，asmeasuredfromthebaseofbeaktotheoil—gland。Soagain，whenthissameTumblerandtherock—pigeonwerecomparedbythelengthoftheirwings，orbytheextremelengthoftheirbodies，thefeetoftheTumblerwerelikewisefoundtobetooshortinverynearlythesameproportion。Iamwellawarethatthemeasurementspretendtogreateraccuracythanispossible，butitwaslesstroubletowritedowntheactualmeasurementsgivenbythecompassesineachcasethananapproximation。
　　TABLE5。II。
　　PIGEONSWITHTHEIRBEAKSLONGERTHANTHATOFTHEROCK—PIGEON，PROPORTIONALLYTOTHESIZEOFTHEIRBODIES。
　　Column1。NameofBreed。
　　Column2。ActuallengthofFeet（inches）。
　　Column3。Differencebetweenactualandcalculatedlengthoffeet，inproportiontolengthoffeetandsizeofbodyintheRock—pigeon。
　　Column3a。Tooshortby（inches）。
　　Column3b。Toolongby（inches）。
　　1。2。3a。3b。
　　Wildrock—pigeon（meanmeasurement）。2。02
　　Carrier。2。60……
　　0。31
　　Carrier。2。60……
　　0。25
　　Carrier。2。40……
　　0。21
　　Carrier，Dragon。2。25……
　　0。06
　　BagadottenCarrier。2。80……
　　0。56
　　Scanderoon，white。2。80……
　　0。37
　　Scanderoon，Pigeoncygne。2。85……
　　0。29
　　Runt。2。75……
　　0。27
　　Numberofspecimens。8……8
　　Inthesetwotables（Tables5。I。and5。II。）weseeinthefirstcolumntheactuallengthofthefeetinthirty—sixbirdsbelongingtovariousbreeds，andinthetwoothercolumnsweseebyhowmuchthefeetaretooshortortoolong，accordingtothesizeofbird，incomparisonwiththerock—
　　pigeon。Inthefirsttabletwenty—twospecimenshavetheirfeettooshort，onanaveragebyalittleabovethetenthofaninch（viz……107）;andfivespecimenshavetheirfeetonanaverageaverylittletoolong，namely，by。07ofaninch。Butsomeoftheselattercasescanbeexplained;forinstance，withPoutersthelegsandfeetareselectedforlength，andthusanynaturaltendencytoadiminutioninthelengthofthefeetwillhavebeencounteracted。IntheSwallowandBarb，whenthecalculationwasmadeonanystandardofcomparisonbesidestheoneused（viz。lengthofbodyfrombaseofbeaktooil—gland），thefeetwerefoundtobetoosmall。
　　Inthesecondtablewehaveeightbirds，withtheirbeaksmuchlongerthanintherock—pigeon，bothactuallyandproportionallywiththesizeofbody，andtheirfeetareinanequallymarkedmannerlonger，namely，inproportion，onanaverageby。29ofaninch。IshouldherestatethatinTable5。I。thereareafewpartialexceptionstothebeakbeingproportionallyshorterthanintherock—pigeon:thusthebeakoftheEnglishFrill—backisjustperceptiblylonger，andthatoftheBussorahCarrierofthesamelengthorslightlylonger，thanintherock—pigeon。ThebeaksofSpots，Swallows，andLaughersareonlyaverylittleshorter，orofthesameproportionallength，butslenderer。Nevertheless，thesetwotables，takenconjointly，indicateprettyplainlysomekindofcorrelationbetweenthelengthofthebeakandthesizeofthefeet。Breedersofcattleandhorsesbelievethatthereisananalogousconnectionbetweenthelengthofthelimbsandhead;theyassertthatarace—horsewiththeheadofadray—horse，oragrey—houndwiththeheadofabulldog，wouldbeamonstrousproduction。Asfancypigeonsaregenerallykeptinsmallaviaries，andareabundantlysuppliedwithfood，theymustwalkaboutmuchlessthanthewildrock—pigeon;anditmaybeadmittedashighlyprobablethatthereductioninthesizeofthefeetinthetwenty—twobirdsinthefirsttablehasbeencausedbydisuse（5/38。Inananalogous，butconverse，manner，certainnaturalgroupsoftheColumbidae，frombeingmoreterrestrialintheirhabitsthanotheralliedgroups，havelargerfeet。SeePrinceBonaparte’Coupd’oeilsurl’OrdredesPigeons。’），andthatthisreductionhasactedbycorrelationonthebeaksofthegreatmajorityofthebirdsinTable5。I。When，ontheotherhand，thebeakhasbeenmuchelongatedbythecontinuedselectionofsuccessiveslightincrementsoflength，thefeetbycorrelationhavelikewisebecomemuchelongatedincomparisonwiththoseofthewildrock—pigeon，notwithstandingtheirlesseneduse。
　　AsIhadtakenmeasuresfromtheendofthemiddletoetotheheelofthetarsusintherock—pigeonandintheabovethirty—sixbirds，Ihavemadecalculationsanalogouswiththoseabovegiven，andtheresultisthesame——
　　namely，thatintheshort—beakedbreeds，withequallyfewexceptionsasintheformercase，themiddletoeconjointlywiththetarsushasdecreasedinlength;whereasinthelong—beakedbreedsithasincreasedinlength，thoughnotquitesouniformlyasintheformercase，fortheleg，insomevarietiesoftheRuntvariesmuchinlength。
　　LENGTHOFSTERNUM。
　　Asfancypigeonsaregenerallyconfinedinaviariesofmoderatesize，andasevenwhennotconfinedtheydonotsearchfortheirownfood，theymustduringmanygenerationshaveusedtheirwingsincomparablylessthanthewildrock—pigeon。Henceitseemedtomeprobablethatallthepartsoftheskeletonsubservienttoflightwouldbefoundtobereducedinsize。Withrespecttothesternum，Ihavecarefullymeasureditsextremelengthintwelvebirdsofdifferentbreeds，andintwowildrock—pigeonsfromtheShetlandIslands。FortheproportionalcomparisonIhavetriedthreestandardsofmeasurement，withalltwelvebirdsnamely，thelengthfromthebaseofthebeaktotheoil—gland，totheendofthetail，andfromtheextremetiptotipofwings。Theresulthasbeenineachcasenearlythesame，thesternumbeinginvariablyfoundtobeshorterthaninthewildrock—pigeon。Iwillgiveonlyasingletable，ascalculatedbythestandardfromthebaseofthebeaktotheoil—gland;fortheresultinthiscaseisnearlythemeanbetweentheresultsobtainedbythetwootherstandards。
　　TABLE5。III。
　　LENGTHOFSTERNUM。
　　Column1。NameofBreed。
　　Column2。ActualLengthinInches。
　　Column3。Tooshortby（inches）。
　　1。2。3。
　　WildRock—pigeon。2。55
　　PiedScanderoon。2。800。60
　　BagadottenCarrier。2。800。17
　　Dragon。2。450。41
　　Carrier。2。750。35
　　Short—facedTumbler。2。050。28
　　Barb。2。350。34
　　Nun。2。270。15
　　GermanPouter。2。360。54
　　Jacobin。2。330。22
　　EnglishFrill—back。2。400。43
　　Swallow。2。450。17
　　Thistable（Table5。III。）showsthatinthesetwelvebreedsthesternumisofanaverageone—thirdofaninch（exactly。332）shorterthanintherock—
　　pigeon，proportionallywiththesizeoftheirbodies;sothatthesternumhasbeenreducedbybetweenone—seventhandone—eighthofitsentirelength;andthisisaconsiderablereduction。
　　Ihavealsomeasuredintwenty—onebirds，includingtheabovedozen，theprominenceofthecrestofthesternumrelativelytoitslength，independentlyofthesizeofthebody。Intwoofthetwenty—onebirdsthecrestwasprominentinthesamerelativedegreeasintherock—pigeon;insevenitwasmoreprominent;butinfiveoutoftheseseven，namely，inaFantail，twoScanderoons，andtwoEnglishCarriers，thisgreaterprominencemaytoacertainextentbeexplained，asaprominentbreastisadmiredandselectedbyfanciers;intheremainingtwelvebirdstheprominencewasless。Henceitfollowsthatthecrestexhibitsaslight，thoughuncertain，tendencytobereducedinprominenceinagreaterdegreethandoesthelengthofthesternumrelativelytothesizeofbody，incomparisonwiththerock—pigeon。
　　Ihavemeasuredthelengthofthescapulainninedifferentlargeandsmall—sizedbreeds，andinallthescapulaisproportionallyshorter（takingthesamestandardasbefore）thaninthewildrock—pigeon。Thereductioninlengthonanaverageisverynearlyone—fifthofaninch，oraboutone—ninthofthelengthofthescapulaintherock—pigeon。
　　ThearmsofthefurculainallthespecimenswhichIcompared，divergedless，proportionallywiththesizeofbody，thanintherock—pigeon;andthewholefurculumwasproportionallyshorter。ThusinaRunt，whichmeasuredfromtiptotipofwings381/2inches，thefurculumwasonlyaverylittlelonger（withthearmshardlymoredivergent）thaninarock—
　　pigeonwhichmeasuredfromtiptotip261/2inches。InaBarb，whichinallitsmeasurementswasalittlelargerthanthesamerock—pigeon，thefurculumwasaquarterofaninchshorter。InaPouter，thefurculumhadnotbeenlengthenedproportionallywiththeincreasedlengthofthebody。
　　InaShort—facedTumbler，whichmeasuredfromtiptotipofwings24
　　inches，thereforeonly21/2incheslessthantherock—pigeon，thefurculumwasbarelytwo—thirdsofthelengthofthatoftherock—pigeon。]
　　Wethusclearlyseethatthesternum，scapula，andfurculumareallreducedinproportionallength;butwhenweturntothewingswefindwhatatfirstappearsawhollydifferentandunexpectedresult。ImayhereremarkthatI
　　havenotpickedoutspecimens，buthaveusedeverymeasurementmadebyme。
　　Takingthelengthfromthebaseofbeaktotheendofthetailasthestandardofcomparison，Ifindthat，outofthirty—fivebirdsofvariousbreeds，twenty—fivehavewingsofgreater，andtenhavethemoflessproportionallength，thanintherock—pigeon。Butfromthefrequentlycorrelatedlengthofthetailandwing—feathers，itisbettertotakeasthestandardofcomparisonthelengthfromthebaseofthebeaktotheoil—
　　gland;andbythisstandard，outoftwenty—sixofthesamebirdswhichhadbeenthusmeasured，twenty—onehadwingstoolong，andonlyfivehadthemtooshort。Inthetwenty—onebirdsthewingsexceededinlengththoseoftherock—pigeon，onanaverage，by11/3inch;whilstinthefivebirdstheywerelessinlengthbyonly。8ofaninch。AsIwasmuchsurprisedthatthewingsofcloselyconfinedbirdsshouldthussofrequentlyhavebeenincreasedinlength，itoccurredtomethatitmightbesolelyduetothegreaterlengthofthewing—feathers;forthiscertainlyisthecasewiththeJacobin，whichhaswingsofunusuallength。AsinalmosteverycaseIhadmeasuredthefoldedwings，Isubtractedthelengthofthisterminalpartfromthatoftheexpandedwings，andthusIobtained，withamoderatedegreeofaccuracy，thelengthofthewingsfromtheendsofthetworadii，answeringfromwristtowristinourarms。Thewings，thusmeasuredinthesametwenty—fivebirds，nowgaveawidelydifferentresult;
　　fortheywereproportionallywiththoseoftherock—pigeontooshortinseventeenbirds，andinonlyeighttoolong。Oftheseeightbirds，fivewerelong—beaked（5/39。ItperhapsdeservesnoticethatbesidesthesefivebirdstwooftheeightwereBarbs，which，asIhaveshown，mustbeclassedinthesamegroupwiththelong—beakedCarriersandRunts。Barbsmayproperlybecalledshort—beakedCarriers。Itwould，therefore，appearasif，duringthereductionoftheirbeaks，theirwingshadretainedalittleofthatexcessoflengthwhichischaracteristicoftheirnearestrelationsandprogenitors。），andthisfactperhapsindicatesthatthereissomecorrelationofthelengthofthebeakwiththelengthofthebonesofthewings，inthesamemanneraswiththatofthefeetandtarsi。Theshorteningofthehumerusandradiusintheseventeenbirdsmayprobablybeattributedtodisuse，asinthecaseofthescapulaandfurculumtowhichthewing—bonesareattached;——thelengtheningofthewing—feathers，andconsequentlytheexpansionofthewingsfromtiptotip，being，ontheotherhand，ascompletelyindependentofuseanddisuseasisthegrowthofthehairorwoolonourlong—haireddogsorlong—woolledsheep。
　　Tosumup:wemayconfidentlyadmitthatthelengthofthesternum，andfrequentlytheprominenceofitscrest，thelengthofthescapulaandfurculum，haveallbeenreducedinsizeincomparisonwiththesamepartsintherock—pigeon。AndIpresumethatthismaybeattributedtodisuseorlessenedexercise。Thewings，asmeasuredfromtheendsoftheradii，havelikewisebeengenerallyreducedinlength;but，owingtotheincreasedgrowthofthewing—feathers，thewings，fromtiptotip，arecommonlylongerthanintherock—pigeon。Thefeet，aswellasthetarsiconjointlywiththemiddletoe，havelikewiseinmostcasesbecomereduced;andthisitisprobablehasbeencausedbytheirlesseneduse;buttheexistenceofsomesortofcorrelationbetweenthefeetandbeakisshownmoreplainlythantheeffectsofdisuse。Wehavealsosomefaintindicationofasimilarcorrelationbetweenthemainbonesofthewingandthebeak。
　　SUMMARYONTHEPOINTSOFDIFFERENCEBETWEENTHESEVERALDOMESTICRACES，AND
　　BETWEENTHEINDIVIDUALBIRDS。
　　Thebeak，togetherwiththebonesoftheface，differremarkablyinlength，breadth，shape，andcurvature。Theskulldiffersinshape，andgreatlyintheangleformedbytheunionofthepre—maxillary，nasal，andmaxillo—
　　jugalbones。Thecurvatureofthelowerjawandthereflectionofitsuppermargin，aswellasthegapeofthemouth，differinahighlyremarkablemanner。Thetonguevariesmuchinlength，bothindependentlyandincorrelationwiththelengthofthebeak。Thedevelopmentofthenaked，wattledskinoverthenostrilsandroundtheeyesvariesinanextremedegree。Theeyelidsandtheexternalorificesofthenostrilsvaryinlength，andaretoacertainextentcorrelatedwiththedegreeofdevelopmentofthewattle。Thesizeandformoftheoesophagusandcrop，andtheircapacityforinflation，differimmensely。Thelengthoftheneckvaries。Withthevaryingshapeofthebody，thebreadthandnumberoftheribs，thepresenceofprocesses，thenumberofthesacralvertebrae，andthelengthofthesternum，allvary。Thenumberandsizeofthecoccygealvertebraevary，apparentlyincorrelationwiththeincreasedsizeofthetail。Thesizeandshapeoftheperforationsinthesternum，andthesizeanddivergenceofthearmsofthefurculum，differ。Theoil—glandvariesindevelopment，andissometimesquiteaborted。Thedirectionandlengthofcertainfeathershavebeenmuchmodified，asinthehoodoftheJacobinandthefrilloftheTurbit。Thewingandtail—feathersgenerallyvaryinlengthtogether，butsometimesindependentlyofeachotherandofthesizeofthebody。Thenumberandpositionofthetail—feathervarytoanunparalleleddegree。Theprimaryandsecondarywing—feathersoccasionallyvaryinnumber，apparentlyincorrelationwiththelengthofthewing。Thelengthofthelegandthesizeofthefeet，and，inconnectionwiththelatter，thenumberofthescutellae，allvary。Awebofskinsometimesconnectsthebasesofthetwoinnertoes，andalmostinvariablythetwooutertoeswhenthefeetarefeathered。
　　Thesizeofthebodydiffersgreatly:aRunthasbeenknowntoweighmorethanfivetimesasmuchasaShort—facedTumbler。Theeggsdifferinsizeandshape。AccordingtoParmentier（5/40。Temminck’Hist。Nat。Gen。desPigeonsetdesGallinaces’tome11813page170。），someracesusemuchstrawinbuildingtheirnests，andothersuselittle;butIcannothearofanyrecentcorroborationofthisstatement。Thelengthoftimerequiredforhatchingtheeggsisuniforminallthebreeds。Theperiodatwhichthecharacteristicplumageofsomebreedsisacquired，andatwhichcertainchangesofcoloursupervene，differs。Thedegreetowhichtheyoungbirdsareclothedwithdownwhenfirsthatchedisdifferent，andiscorrelatedinasingularmannerwiththecolouroftheplumage。Themannerofflight，andcertaininheritedmovements，suchasclappingthewings，tumblingeitherintheairorontheground，andthemannerofcourtingthefemale，presentthemostsingulardifferences。Indispositiontheseveralracesdiffer。
　　Someracesareverysilent;otherscooinahighlypeculiarmanner。
　　Althoughmanydifferentraceshavekepttrueincharacterduringseveralcenturies，asweshallhereaftermorefullysee，yetthereisfarmoreindividualvariabilityinthemostconstantbreedsthaninbirdsinastateofnature。Thereishardlyanyexceptiontotherulethatthosecharactersvarymostwhicharenowmostvaluedandattendedtobyfanciers，andwhichconsequentlyarenowbeingimprovedbycontinuedselection。Thisisindirectlyadmittedbyfancierswhentheycomplainthatitismuchmoredifficulttobreedhighfancypigeonsuptotheproperstandardofexcellencethantheso—calledtoypigeons，whichdifferfromeachothermerelyincolour;forparticularcolourswhenonceacquiredarenotliabletocontinuedimprovementoraugmentation。Somecharactersbecomeattached，fromquiteunknowncauses，morestronglytothemalethantothefemalesex;sothatwehaveincertainraces，atendencytowardstheappearanceofsecondarysexualcharacters（5/41。ThistermwasusedbyJohnHunterforsuchdifferencesinstructurebetweenthemalesandfemales，asarenotdirectlyconnectedwiththeactofreproduction，asthetailofthepeacock，thehornsofdeer，etc。）ofwhichtheaboriginalrock—pigeondisplaysnotatrace。
　　CHAPTER1。VI。
　　PIGEONS——continued。
　　ONTHEABORIGINALPARENT—STOCKOFTHESEVERALDOMESTICRACES。
　　HABITSOFLIFE。
　　WILDRACESOFTHEROCK—PIGEON。
　　DOVECOTE—PIGEONS。
　　PROOFSOFTHEDESCENTOFTHESEVERALRACESFROMCOLUMBALIVIA。
　　FERTILITYOFTHERACESWHENCROSSED。
　　REVERSIONTOTHEPLUMAGEOFTHEWILDROCK—PIGEON。
　　CIRCUMSTANCESFAVOURABLETOTHEFORMATIONOFTHERACES。
　　ANTIQUITYANDHISTORYOFTHEPRINCIPALRACES。
　　MANNEROFTHEIRFORMATION。
　　SELECTION。
　　UNCONSCIOUSSELECTION。
　　CARETAKENBYFANCIERSINSELECTINGTHEIRBIRDS。
　　SLIGHTLYDIFFERENTSTRAINSGRADUALLYCHANGEINTOWELL—MARKEDBREEDS。
　　EXTINCTIONOFINTERMEDIATEFORMS。
　　CERTAINBREEDSREMAINPERMANENT，WHILSTOTHERSCHANGE。
　　SUMMARY。
　　Thedifferencesdescribedinthelastchapterbetweentheelevenchiefdomesticracesandbetweenindividualbirdsofthesamerace，wouldbeoflittlesignificance，iftheyhadnotalldescendedfromasinglewildstock。Thequestionoftheiroriginisthereforeoffundamentalimportance，andmustbediscussedatconsiderablelength。Noonewillthinkthissuperfluouswhoconsidersthegreatamountofdifferencebetweentheraces，whoknowshowancientmanyofthemare，andhowtrulytheybreedatthepresentday。Fanciersalmostunanimouslybelievethatthedifferentracesaredescendedfromseveralwildstocks，whereasmostnaturalistsbelievethatallaredescendedfromtheColumbaliviaorrock—pigeon。
　　Temminck（6/1。Temminck’Hist。Nat。Gen。desPigeons’etc。tome1page191。）haswellobserved，andMr。Gouldhasmadethesameremarktome，thattheaboriginalparentmusthavebeenaspecieswhichroostedandbuiltitsnestonrocks;andImayaddthatitmusthavebeenasocialbird。Forallthedomesticracesarehighlysocial，andnoneareknowntobuildorhabituallytoroostontrees。Theawkwardmannerinwhichsomepigeons，keptbymeinasummer—housenearanoldwalnut—tree，occasionallyalightedonthebarerbranches，wasevident。（6/2。IhaveheardthroughSirC。LyellfromMissBuckley，thatsomehalf—bredCarrierskeptduringmanyyearsnearLondonregularlysettledbydayonsomeadjoiningtrees，and，afterbeingdisturbedintheirloftbytheiryoungbeingtaken，roostedonthematnight。）Nevertheless，Mr。R。ScotSkirvinginformsmethatheoftensawcrowdsofpigeonsinUpperEgyptsettlingonlowtrees，butnotonpalms，inpreferencetoalightingonthemudhovelsofthenatives。InIndiaMr。
　　Blyth（6/3。’AnnalsandMag。ofNat。Hist。’2ndseriesvolume201857page509;andinalatevolumeofthe’JournaloftheAsiaticSociety。’）hasbeenassuredthatthewildC。livia，var。intermedia，sometimesroostsintrees。Imayheregiveacuriousinstanceofcompulsionleadingtochangedhabits:thebanksoftheNileabovelat。28deg30’areperpendicularforalongdistance，sothatwhentheriverisfullthepigeonscannotalightontheshoretodrink，andMr。Skirvingrepeatedlysawwholeflockssettleonthewater，anddrinkwhilsttheyfloateddownthestream。Theseflocksseenfromadistanceresembledflocksofgullsonthesurfaceofthesea。
　　Ifanydomesticracehaddescendedfromaspecieswhichwasnotsocial，orwhichbuiltitsnestandroostedintrees（6/4。InworkswrittenonthepigeonbyfanciersIhavesometimesobservedthemistakenbeliefexpressedthatthespecieswhichnaturalistscalledground—pigeons（incontradistinctiontoarborealpigeons）donotperchandbuildontrees。Inthesesameworksbyfancierswildspeciesresemblingthechiefdomesticracesareoftensaidtoexistinvariouspartsoftheworld;butsuchspeciesarequiteunknowntonaturalists。）thesharpeyesoffancierswouldassuredlyhavedetectedsomevestigeofsodifferentanaboriginalhabit。
　　Forwehavereasontobelievethataboriginalhabitsarelongretainedunderdomestication。Thuswiththecommonassweseesignsofitsoriginaldesertlifeinitsstrongdisliketocrossthesmalleststreamofwater，andinitspleasureinrollinginthedust。Thesamestrongdisliketocrossastreamiscommontothecamel，whichhasbeendomesticatedfromaveryancientperiod。Youngpigs，thoughsotame，sometimessquatwhenfrightened，andthustrytoconcealthemselvesevenonanopenandbareplace。Youngturkeys，andoccasionallyevenyoungfowls，whenthehengivesthedanger—cry，runawayandtrytohidethemselves，likeyoungpartridgesorpheasants，inorderthattheirmothermaytakeflight，ofwhichshehaslostthepower。Themusk—duck（Cairinamoschata）initsnativecountryoftenperchesandroostsontrees（6/5。SirR。Schomburgkin’JournalR。
　　Geograph。Soc。’volume131844page32。），andourdomesticatedmusk—ducks，thoughsuchsluggishbirds，"arefondofperchingonthetopsofbarns，walls，etc。，and，ifallowedtospendthenightinthehen—house，thefemalewillgenerallygotoroostbythesideofthehens，butthedrakeistooheavytomountthitherwithease。"（6/6。Rev。E。S。Dixon’OrnamentalPoultry’1848pages63，66。）Weknowthatthedog，howeverwellandregularlyfed，oftenburies，likethefox，anysuperfluousfood;andweseehimturningroundandroundonacarpet，asiftotrampledowngrasstoformabed;weseehimonbarepavementsscratchingbackwardsasiftothrowearthoverhisexcrement，although，asIbelieve，thisisnevereffectedevenwherethereisearth。Inthedelightwithwhichlambsandkidscrowdtogetherandfriskonthesmallesthillock，weseeavestigeoftheirformeralpinehabits。
　　Wehavethereforegoodreasontobelievethatallthedomesticracesofthepigeonaredescendedeitherfromsomeoneorfromseveralspecieswhichbothroostedandbuilttheirnestsonrocks，andweresocialindisposition。Asonlyfiveorsixwildspecieshavethesehabits，andmakeanynearapproachinstructuretothedomesticatedpigeon，Iwillenumeratethem。
　　[Firstly，theColumbaleuconotaresemblescertaindomesticvarietiesinitsplumage，withtheonemarkedandnever—failingdifferenceofawhitebandwhichcrossesthetailatsomedistancefromtheextremity。Thisspecies，moreover，inhabitstheHimalaya，closetothelimitofperpetualsnow;andtherefore，asMr。Blythhasremarked，isnotlikelytohavebeentheparentofourdomesticbreeds，whichthriveinthehottestcountries。Secondly，theC。rupestris，ofCentralAsia，whichisintermediate（6/7。’Proc。
　　Zoolog。Soc。’1859page400。）betweentheC。leuconotaandlivia;buthasnearlythesamecolouredtailastheformerspecies。Thirdly，theColumbalittoralisbuildsandroosts，accordingtoTemminck，onrocksintheMalayanarchipelago;itiswhite，exceptingpartsofthewingandthetipofthetail，whichareblack;itslegsarelivid—coloured，andthisisacharacternotobservedinanyadultdomesticpigeon;butIneednothavementionedthisspeciesortheclosely—alliedC。luctuosa，astheyinfactbelongtothegenusCarpophaga。Fourthly，Columbaguinea，whichrangesfromGuinea（6/8。Temminck’Hist。Nat。Gen。desPigeons’tome1;also’LesPigeons’parMme。KnipandTemminck。Bonaparte，however，inhis’Coup—
　　d’oeil’believesthattwocloselyalliedspeciesareconfoundedtogetherunderthisname。TheC。leucocephalaoftheWestIndiesisstatedbyTemmincktobearock—pigeon;butIaminformedbyMr。Gossethatthisisanerror。）totheCapeofGoodHope，androostseitherontreesorrocks，accordingtothenatureofthecountry。ThisspeciesbelongstothegenusStrictoenasofReichenbach，butiscloselyalliedtoColumba;itistosomeextentcolouredlikecertaindomesticraces，andhasbeensaidtobedomesticatedinAbyssinia;butMr。MansfieldParkyns，whocollectedthebirdsofthatcountryandknowsthespecies，informsmethatthisisamistake。Moreover，theC。guineaischaracterisedbythefeathersoftheneckhavingpeculiarnotchedtips，——acharacternotobservedinanydomesticrace。Fifthly，theColumbaoenasofEurope，whichroostsontrees，andbuildsitsnestinholes，eitherintreesortheground;thisspecies，asfarasexternalcharactersgo，mightbetheparentofseveraldomesticraces;but，thoughitcrossesreadilywiththetruerock—pigeon，theoffspring，asweshallpresentlysee，aresterilehybrids，andofsuchsterilitythereisnotatracewhenthedomesticracesareintercrossed。Itshouldalsobeobservedthatifweweretoadmit，againstallprobability，thatanyoftheforegoingfiveorsixspeciesweretheparentsofsomeofourdomesticpigeons，nottheleastlightwouldbethrownonthechiefdifferencesbetweentheelevenmoststrongly—markedraces。
　　Wenowcometothebestknownrock—pigeon，theColumbalivia，whichisoftendesignatedinEuropepre—eminentlyastheRock—pigeon，andwhichnaturalistsbelievetobetheparentofallthedomesticatedbreeds。Thisbirdagreesineveryessentialcharacterwiththebreedswhichhavebeenonlyslightlymodified。Itdiffersfromallotherspeciesinbeingofaslaty—bluecolour，withtwoblackbarsonthewings，andwiththecroup（orloins）white。OccasionallybirdsareseeninFaroeandtheHebrideswiththeblackbarsreplacedbytwoorthreeblackspots;thisformhasbeennamedbyBrehm（6/9。’HandbuchderNaturgesch。VogelDeutschlands。’）C。
　　amaliae，butthisspecieshasnotbeenadmittedasdistinctbyotherornithologists。Graba（6/10。’Tagebuch，ReisenachFaro’1830s。62。）evenfoundadifferenceinthebarsontherightandleftwingsofthesamebirdinFaroe。AnotherandrathermoredistinctformiseithertrulywildorhasbecomeferalonthecliffsofEnglandandwasdoubtfullynamedbyMr。Blyth（6/11。’AnnalsandMag。ofNat。Hist。’volume191847page102。Thisexcellentpaperonpigeonsiswellworthconsulting。）asC。affinis，butisnownolongerconsideredbyhimasadistinctspecies。C。affinisisrathersmallerthantherock—pigeonoftheScottishislands，andhasaverydifferentappearanceowingtothewing—covertsbeingchequeredwithblack，withsimilarmarksoftenextendingovertheback。Thechequeringconsistsofalargeblackspotonthetwosides，butchieflyontheouterside，ofeachfeather。Thewing—barsinthetruerock—pigeonandinthechequeredvarietyare，infact，duetosimilarthoughlargerspotssymmetricallycrossingthesecondarywing—featherandthelargercoverts。Hencethechequeringarisesmerelyfromanextensionofthesemarkstootherpartsoftheplumage。ChequeredbirdsarenotconfinedtothecoastsofEngland;fortheywerefoundbyGrabaatFaroe;andW。Thompson（6/12。’NaturalHistoryofIreland’Birdsvolume21850page11。ForGrabaseepreviousreference。）
　　saysthatatIslayfullyhalfthewildrock—pigeonswerechequered。ColonelKing，ofHythe，stockedhisdovecotewithyoungwildbirdswhichhehimselfprocuredfromnestsattheOrkneyIslands;andseveralspecimens，kindlysenttomebyhim，wereallplainlychequered。Aswethusseethatchequeredbirdsoccurmingledwiththetruerock—pigeonatthreedistinctsites，namely，Faroe，theOrkneyIslands，andIslay，noimportancecanbeattachedtothisnaturalvariationintheplumage。
　　PrinceC。L。Bonaparte（6/13。’Coup—d’oeilsurl’OrdredesPigeons’’ComptesRendus’1854—55。），agreatdividerofspecies，enumerates，withamarkofinterrogation，asdistinctfromC。livia，theC。turricolaofItaly，theC。
　　rupestrisofDaouria，andtheC。schimperiofAbyssinia;butthesebirdsdifferfromC。liviaincharactersofthemosttriflingvalue。IntheBritishMuseumthereisachequeredpigeon，probablytheC。schimperiofBonaparte，fromAbyssinia。TothesemaybeaddedtheC。gymnocyclusofG。R。
　　GrayfromW。Africa，whichisslightlymoredistinct，andhasrathermorenakedskinroundtheeyesthantherock—pigeon;butfrominformationgivenmebyDr。Daniell，itisdoubtfulwhetherthisisawildbird，fordovecote—pigeons（whichIhaveexamined）arekeptonthecoastofGuinea。
　　Thewildrock—pigeonofIndia（C。intermediaofStrickland）hasbeenmoregenerallyacceptedasadistinctspecies。Itdifferschieflyinthecroupbeingblueinsteadofsnow—white;butasMr。Blythinformsme，thetintvaries，beingsometimesalbescent。Whenthisformisdomesticatedchequeredbirdsappear，justasoccursinEuropewiththetrulywildC。livia。
　　Moreoverweshallimmediatelyhaveproofthattheblueandwhitecroupisahighlyvariablecharacter;andBechstein（6/14。’NaturgeschichteDeutschlands’b。41795s。14。）assertsthatwithdovecote—pigeonsinGermanythisisthemostvariableofallthecharactersoftheplumage。
　　HenceitmaybeconcludedthatC。intermediacannotberankedasspecificallydistinctfromC。livia。
　　InMadeirathereisarock—pigeonwhichafewornithologistshavesuspectedtobedistinctfromC。livia。IhaveexaminednumerousspecimenscollectedbyMr。E。V。HarcourtandMr。Mason。Theyarerathersmallerthantherock—
　　pigeonfromtheShetlandIslands，andtheirbeaksareplainlythinner，butthethicknessofthebeakvariedintheseveralspecimens。Inplumagethereisremarkablediversity;somespecimensareidenticalineveryfeather（I
　　speakafteractualcomparison）withtherock—pigeonoftheShetlandIslands;othersarechequered，likeC。affinisfromthecliffsofEngland，butgenerallytoagreaterdegree，beingalmostblackoverthewholeback;
　　othersareidenticalwiththeso—calledC。intermediaofIndiainthedegreeofbluenessofthecroup;whilstothershavethispartverypaleorverydarkblue，andarelikewisechequered。Somuchvariabilityraisesastrongsuspicionthatthesebirdsaredomesticpigeonswhichhavebecomeferal。
　　FromthesefactsitcanhardlybedoubtedthatC。livia，affinis，intermedia，andtheformsmarkedwithaninterrogationbyBonaparteoughtalltobeincludedunderasinglespecies。Butitisquiteimmaterialwhetherornottheyarethusranked，andwhethersomeoneoftheseformsorallaretheprogenitorsofthevariousdomestickinds，asfarasanylightcanthusbethrownonthedifferencesbetweenthemorestrongly—markedraces。Thatcommondovecote—pigeons，whicharekeptinvariouspartsoftheworld，aredescendedfromoneorfromseveraloftheabove—mentionedwildvarietiesofC。livia，noonewhocomparesthemwilldoubt。Butbeforemakingafewremarksondovecote—pigeons，itshouldbestatedthatthewildrock—pigeonhasbeenfoundeasytotameinseveralcountries。WehaveseenthatColonelKingatHythestockedhisdovecotemorethantwentyyearsagowithyoungwildbirdstakenattheOrkneyIslands，andsincethentheyhavegreatlymultiplied。TheaccurateMacgillivray（6/15。’HistoryofBritishBirds’volume1pages275—284。Mr。AndrewDuncantamedarock—pigeonintheShetlandIslands。Mr。JamesBarclay，andMr。SmithofUyeaSound，bothsaythatthewildrock—pigeoncanbeeasilytamed;andtheformergentlemanassertsthatthetamedbirdsbreedfourtimesayear。Dr。LawrenceEdmondstoneinformsmethatawildrock—pigeoncameandsettledinhisdovecoteinBaltaSoundintheShetlandIslands，andbredwithhispigeons;
　　hehasalsogivenmeotherinstancesofthewildrock—pigeonhavingbeentakenyoungandbreedingincaptivity。）assertsthathecompletelytamedawildrock—pigeonintheHebrides;andseveralaccountsareonrecordsofthesepigeonshavingbredindovecotesintheShetlandIslands。InIndia，asCaptainHuttoninformsme，thewildrock—pigeoniseasilytamed，andbreedsreadilywiththedomestickind;andMr。Blyth（6/16。’AnnalsandMag。ofNat。History’volume191847page103andvolumefor1857page512。）assertsthatwildbirdscomefrequentlytothedovecotesandminglefreelywiththeirinhabitants。Intheancient’AyeenAkbery’itiswrittenthat，ifafewwildpigeonsbetaken，"theyarespeedilyjoinedbyathousandothersoftheirkind。"
　　Dovecote—pigeonsarethosewhicharekeptindovecotesinasemi—