IfthehistoryofthesePortoSantorabbitshadnotbeenknown，mostnaturalists，onobservingtheirmuchreducedsize，theircolour，reddishaboveandgreybeneath，theirtailsandearsnottippedwithblack，wouldhaverankedthemasadistinctspecies。TheywouldhavebeenstronglyconfirmedinthisviewbyseeingthemaliveintheZoologicalGardens，andhearingthattheyrefusedtocouplewithotherrabbits。Yetthisrabbit，whichtherecanbelittledoubtwouldthushavebeenrankedasadistinctspecies，ascertainlyoriginatedsincetheyear1420。Finally，fromthethreecasesoftherabbitswhichhaverunwildinPortoSanto，Jamaica，andtheFalklandIslands，weseethattheseanimalsdonot，undernewconditionsoflife，reverttoorretaintheiraboriginalcharacter，asissogenerallyassertedtobethecasebymostauthors。
OSTEOLOGICALCHARACTERS。
Whenweremember，ontheonehand，howfrequentlyitisstatedthatimportantpartsofthestructurenevervary;and，ontheotherhand，onwhatsmalldifferencesintheskeletonfossilspecieshaveoftenbeenfounded，thevariabilityoftheskullandofsomeotherbonesinthedomesticatedrabbitwelldeservesattention。Itmustnotbesupposedthatthemoreimportantdifferencesimmediatelytobedescribedstrictlycharacteriseanyonebreed;allthatcanbesaidis，thattheyaregenerallypresentincertainbreeds。Weshouldbearinmindthatselectionhasnotbeenappliedtofixanycharacterintheskeleton，andthattheanimalshavenothadtosupportthemselvesunderuniformhabitsoflife。Wecannotaccountformostofthedifferencesintheskeleton;butweshallseethattheincreasedsizeofthebody，duetocarefulnurtureandcontinuedselection，hasaffectedtheheadinaparticularmanner。Eventheelongationandloppingoftheearshaveinfluencedinasmalldegreetheformofthewholeskull。Thewantofexercisehasapparentlymodifiedtheproportionallengthofthelimbsincomparisonwiththatofthebody。
[Asastandardofcomparison，IpreparedskeletonsoftwowildrabbitsfromKent，onefromtheShetlandIslands，andonefromAntriminIreland。Asallthebonesinthesefourspecimensfromsuchdistantlocalitiescloselyresembledeachother，presentingscarcelyanyappreciabledifference，itmaybeconcludedthatthebonesofthewildrabbitaregenerallyuniformincharacter。
SKULL。