MERCHANTSoccasionallygothroughawholesome，thoughtroublesomeandnotalwayssatisfactory，processwhichtheyterm\"takingstock。\"Afteralltheexcitementofspeculation，thepleasureofgain，andthepainofloss，thetradermakesuphismindtofacefactsandtolearntheexactquantityandqualityofhissolidandreliablepossessions。
Themanofsciencedoeswellsometimestoimitatethisprocedure；and，forgettingforthetimetheimportanceofhisownsmallwinnings，tore—examinethecommonstockintrade，sothathemaymakesurehowfarthestockofbullioninthecellar——onthefaithofwhoseexistencesomuchpaperhasbeencirculating——isreallythesolidgoldoftruth。
TheAnniversaryMeetingoftheGeologicalSocietyseemstobeanoccasionwellsuitedforanundertakingofthiskind——foraninquiry，infact，intothenatureandvalueofthepresentresultsofpaleontologicalinvestigation；andthemoreso，asallthosewhohavepaidcloseattentiontothelatemultitudinousdiscussionsinwhichpaleontologyisimplicated，musthavefelttheurgentnecessityofsomesuchscrutiny。
Firstinorder，asthemostdefiniteandunquestionableofalltheresultsofpaleontology，mustbementionedtheimmenseextensionandimpulsegiventobotany，zoology，andcomparativeanatomy，bytheinvestigationoffossilremains。Indeed，themassofbiologicalfactshasbeensogreatlyincreased，andtherangeofbiologicalspeculationhasbeensovastlywidened，bytheresearchesofthegeologistandpaleontologist，thatitistobefearedtherearenaturalistsinexistencewholookupongeologyasBrindleyregardedrivers。\"Rivers，\"
saidthegreatengineer，\"weremadetofeedcanals\"；andgeology，someseemtothink，wassolelycreatedtoadvancecomparativeanatomy。
Weresuchathoughtjustifiable，itcouldhardlyexpecttobereceivedwithfavourbythisassembly。Butitisnotjustifiable。Yourfavouritesciencehasherowngreataimsindependentofallothers；andif，notwithstandinghersteadydevotiontoherownprogress，shecanscattersuchrichalmsamonghersisters，itshouldberememberedthathercharityisofthesortthatdoesnotimpoverish，but\"blessethhimthatgivesandhimthattakes。\"
Regardthematteraswewill，however，thefactsremain。Nearly40，000
speciesofanimalsandplantshavebeenaddedtotheSystemaNaturaebypaleontologicresearch。Thisisalivingpopulationequivalenttothatofanewcontinentinmerenumber；equivalenttothatofanewhemisphere，ifwetakeintoaccountthesmallpopulationofinsectsasyetfoundfossil，andthelargeproportionandpeculiarorganizationofmanyoftheVertebrata。
But，beyondthis，itisperhapsnottoomuchtosaythat，exceptforthenecessityofinterpretingpaleontologicfacts，thelawsofdistributionwouldhavereceivedlesscarefulstudy；whilefewcomparativeanatomists（andthosenotofthefirstorder）wouldhavebeeninducedbymereloveofdetail，assuch，tostudytheminutiaeofosteology，wereitnotthatinsuchminutiaelietheonlykeystothemostinterestingriddlesofferedbytheextinctanimalworld。
Theseassuredlyaregreatandsolidgains。Surelyitismatterfornosmallcongratulationthatinhalfacentury（forpaleontology，thoughitdawnedearlier，cameintofulldayonlywithCuvier）asubordinatebranchofbiologyshouldhavedoubledthevalueandtheinterestofthewholegroupofsciencestowhichitbelongs。
Butthisisnotall。Alliedwithgeology，paleontologyhasestablishedtwolawsofinestimableimportance：thefirst，thatoneandthesameareaoftheearth’ssurfacehasbeensuccessivelyoccupiedbyverydifferentkindsoflivingbeings；thesecond，thattheorderofsuccessionestablishedinonelocalityholdsgood，approximately，inall。
Thefirstoftheselawsisuniversalandirreversible；thesecondisaninductionfromavastnumberofobservations，thoughitmaypossibly，andevenprobably，havetoadmitofexceptions。Asaconsequenceofthesecondlaw，itfollowsthatapeculiarrelationfrequentlysubsistsbetweenseriesofstrata，containingorganicremains，indifferentlocalities。Theseriesresembleoneanother，notonlyinvirtueofageneralresemblanceoftheorganicremainsinthetwo，butalsoinvirtueofaresemblanceintheorderandcharacteroftheserialsuccessionineach。Thereisaresemblanceofarrangement；sothattheseparatetermsofeachseries，aswellasthewholeseries，exhibitacorrespondence。
Successionimpliestime；thelowermembersofaseriesofsedimentaryrocksarecertainlyolderthantheupper；andwhenthenotionofagewasonceintroducedastheequivalentofsuccession，itwasnowonderthatcorrespondenceinsuccessioncametobelookeduponasacorrespondenceinage，or\"contemporaneity。\"And，indeed，solongasrelativeageonlyisspokenof，correspondenceinsuccession’is’
correspondenceinage；itis’relative’contemporaneity。
Butitwouldhavebeenverymuchbetterforgeologyifsolooseandambiguousawordas\"contemporaneous\"hadbeenexcludedfromherterminology，andif，initsstead，sometermexpressingsimilarityofserialrelation，andexcludingthenotionoftimealtogether，hadbeenemployedtodenotecorrespondenceinpositionintwoormoreseriesofstrata。
Inanatomy，wheresuchcorrespondenceofpositionhasconstantlytobespokenof，itisdenotedbytheword\"homology\"anditsderivatives；
andforGeology（whichafterallisonlytheanatomyandphysiologyoftheearth）itmightbewelltoinventsomesingleword，suchas\"homotaxis\"（similarityoforder），inordertoexpressanessentiallysimilaridea。This，however，hasnotbeendone，andmostprobablytheinquirywillatoncebemade——Towhatendburdensciencewithanewandstrangeterminplaceofoneold，familiar，andpartofourcommonlanguage？
Thereplytothisquestionwillbecomeobviousastheinquiryintotheresultsofpaleontologyispushedfurther。
Thosewhosebusinessitistoacquaintthemselvesspeciallywiththeworksofpaleontologists，infact，willbefullyawarethatveryfew，ifany，wouldrestsatisfiedwithsuchastatementoftheconclusionsoftheirbranchofbiologyasthatwhichhasjustbeengiven。
Ourstandardrepertoriesofpaleontologyprofesstoteachusfarhigherthings——todisclosetheentiresuccessionoflivingformsuponthesurfaceoftheglobe；totellusofawhollydifferentdistributionofclimaticconditionsinancienttimes；torevealthecharacterofthefirstofalllivingexistences；andtotraceoutthelawofprogressfromthemtous。
Itmaynotbeunprofitabletobestowontheseprofessionsasomewhatmorecriticalexaminationthantheyhavehithertoreceived，inordertoascertainhowfartheyrestonanirrefragablebasis；orwhether，afterall，itmightnotbewellforpaleontologiststolearnalittlemorecarefullythatscientific\"arsartium，\"theartofsaying\"Idon’tknow。\"Andtothisendletusdefinesomewhatmoreexactlytheextentofthesepretensionsofpaleontology。
EveryoneisawarethatProfessorBronn’s’Untersuchungen’andProfessorPictet’s’TraitedePaleontologie’areworksofstandardauthority，familiarlyconsultedbyeveryworkingpaleontologist。Itisdesirabletospeakoftheseexcellentbooks，andoftheirdistinguishedauthors，withtheutmostrespect，andinatoneasfaraspossibleremovedfromcarpingcriticism；indeed，iftheyarespeciallycitedinthisplace，itismerelyinjustificationoftheassertionthatthefollowingpropositions，whichmaybefoundimplicitly，orexplicitly，intheworksinquestion，areregardedbythemassofpaleontologistsandgeologists，notonlyontheContinentbutinthiscountry，asexpressingsomeofthebest—establishedresultsofpaleontology。
Thus：——
Animalsandplantsbegantheirexistencetogether，notlongafterthecommencementofthedepositionofthesedimentaryrocks；andthensucceededoneanother，insuchamanner，thattotallydistinctfaunaeandfloraeoccupiedthewholesurfaceoftheearth，oneaftertheother，andduringdistinctepochsoftime。
Ageologicalformationisthesumofallthestratadepositedoverthewholesurfaceoftheearthduringoneoftheseepochs：ageologicalfaunaorfloraisthesumofallthespeciesofanimalsorplantswhichoccupiedthewholesurfaceoftheglobe，duringoneoftheseepochs。
Thepopulationoftheearth’ssurfacewasatfirstverysimilarinallparts，andonlyfromthemiddleoftheTertiaryepochonwards，begantoshowadistinctdistributioninzones。
Theconstitutionoftheoriginalpopulation，aswellasthenumericalproportionsofitsmembers，indicatesawarmerand，onthewhole，somewhattropicalclimate，whichremainedtolerablyequablethroughouttheyear。Thesubsequentdistributionoflivingbeingsinzonesistheresultofagradualloweringofthegeneraltemperature，whichfirstbegantobefeltatthepoles。
Itisnotnowproposedtoinquirewhetherthesedoctrinesaretrueorfalse；buttodirectyourattentiontoamuchsimplerthoughveryessentialpreliminaryquestion——Whatistheirlogicalbasis？whatarethefundamentalassumptionsuponwhichtheyalllogicallydepend？andwhatistheevidenceonwhichthosefundamentalpropositionsdemandourassent？
Theseassumptionsaretwo：thefirst，thatthecommencementofthegeologicalrecordiscoevalwiththecommencementoflifeontheglobe；
thesecond，thatgeologicalcontemporaneityisthesamethingaschronologicalsynchrony。Withoutthefirstoftheseassumptionstherewouldofcoursebenogroundforanystatementrespectingthecommencementoflife；withoutthesecond，alltheotherstatementscited，everyoneofwhichimpliesaknowledgeofthestateofdifferentpartsoftheearthatoneandthesametime，willbenolessdevoidofdemonstration。
Thefirstassumptionobviouslyrestsentirelyonnegativeevidence。
Thisis，ofcourse，theonlyevidencethatevercanbeavailabletoprovethecommencementofanyseriesofphenomena；but，atthesametime，itmustberecollectedthatthevalueofnegativeevidencedependsentirelyontheamountofpositivecorroborationitreceives。
IfABwishestoprovean’alibi’，itisofnouseforhimtogetathousandwitnessessimplytoswearthattheydidnotseehiminsuchandsuchaplace，unlessthewitnessesarepreparedtoprovethattheymusthaveseenhimhadhebeenthere。ButtheevidencethatanimallifecommencedwiththeLingula—flags，’e。g。’，wouldseemtobeexactlyofthisunsatisfactoryuncorroboratedsort。TheCambrianwitnessessimplyswearthey\"haven’tseenanybodytheirway\"；uponwhichthecounselfortheothersideimmediatelyputsintenortwelvethousandfeetofDevoniansandstonestomakeoaththeyneversawafishoramollusk，thoughalltheworldknowstherewereplentyintheirtime。
Butthenitisurgedthat，thoughtheDevonianrocksinonepartoftheworldexhibitnofossils，inanothertheydo，whilethelowerCambrianrocksnowhereexhibitfossils，andhencenolivingbeingcouldhaveexistedintheirepoch。
Tothistherearetworeplies：thefirst，thattheobservationalbasisoftheassertionthatthelowestrocksarenowherefossiliferousisanamazinglysmallone，seeinghowverysmallanarea，incomparisontothatofthewholeworld，hasyetbeenfullysearched；thesecond，thattheargumentisgoodfornothingunlesstheunfossiliferousrocksinquestionwerenotonly’contemporaneous’inthegeologicalsense，but’synchronous’inthechronologicalsense。Tousethe’alibi’
illustrationagain。Ifamanwishestoprovehewasinneitheroftwoplaces，AandB，onagivenday，hiswitnessesforeachplacemustbepreparedtoanswerforthewholeday。IftheycanonlyprovethathewasnotatAinthemorning，andnotatBintheafternoon，theevidenceofhisabsencefrombothis’nil’，becausehemighthavebeenatBinthemorningandatAintheafternoon。
Thuseverythingdependsuponthevalidityofthesecondassumption。Andwemustproceedtoinquirewhatistherealmeaningoftheword\"contemporaneous\"asemployedbygeologists。Tothisendaconcreteexamplemaybetaken。
TheLiasofEnglandandtheLiasofGermany，theCretaceousrocksofBritainandtheCretaceousrocksofSouthernIndia，aretermedbygeologists\"contemporaneous\"formations；butwheneveranythoughtfulgeologistisaskedwhetherhemeanstosaythattheyweredepositedsynchronously，hesays，\"No，——onlywithinthesamegreatepoch。\"Andif，inpursuingtheinquiry，heisaskedwhatmaybetheapproximatevalueintimeofa\"greatepoch\"——whetheritmeansahundredyears，orathousand，oramillion，ortenmillionyears——hisreplyis，\"Icannottell。\"
Ifthefurtherquestionbeput，whetherphysicalgeologyisinpossessionofanymethodbywhichtheactualsynchrony（orthereverse）
ofanytwodistantdepositscanbeascertained，nosuchmethodcanbeheardof；itbeingadmittedbyallthebestauthoritiesthatneithersimilarityofmineralcomposition，norofphysicalcharacter，norevendirectcontinuityofstratum，are’absolute’proofsofthesynchronismofevenapproximatedsedimentarystrata：while，fordistantdeposits，thereseemstobenokindofphysicalevidenceattainableofanaturecompetenttodecidewhethersuchdepositswereformedsimultaneously，orwhethertheypossessanygivendifferenceofantiquity。Toreturntoanexamplealreadygiven：Allcompetentauthoritieswillprobablyassenttothepropositionthatphysicalgeologydoesnotenableusinanywaytoreplytothisquestion——WeretheBritishCretaceousrocksdepositedatthesametimeasthoseofIndia，oraretheyamillionofyearsyoungeroramillionofyearsolder？
Ispaleontologyabletosucceedwherephysicalgeologyfails？Standardwritersonpaleontology，ashasbeenseen，assumethatshecan。Theytakeitforgranted，thatdepositscontainingsimilarorganicremainsaresynchronous——atanyrateinabroadsense；andyet，thosewhowillstudytheeleventhandtwelfthchaptersofSirHenryDeLaBeche’sremarkable’ResearchesinTheoreticalGeology’，publishednownearlythirtyyearsago，andwillcarryouttheargumentstheremostluminouslystated，totheirlogicalconsequences，mayveryeasilyconvincethemselvesthatevenabsoluteidentityoforganiccontentsisnoproofofthesynchronyofdeposits，whileabsolutediversityisnoproofofdifferenceofdate。SirHenryDeLaBechegoesevenfurther，andadducesconclusiveevidencetoshowthatthedifferentpartsofoneandthesamestratum，havingasimilarcompositionthroughout，containingthesameorganicremains，andhavingsimilarbedsaboveandbelowit，mayyetdiffertoanyconceivableextentinage。
EdwardForbeswasinthehabitofassertingthatthesimilarityoftheorganiccontentsofdistantformationswas’primafacie’evidence，notoftheirsimilarity，butoftheirdifferenceofage；andholdingashedidthedoctrineofsinglespecificcentres，theconclusionwasaslegitimateasanyother；forthetwodistrictsmusthavebeenoccupiedbymigrationfromoneofthetwo，orfromanintermediatespot，andthechancesagainstexactcoincidenceofmigrationandofimbeddingareinfinite。
Inpointoffact，however，whetherthehypothesisofsingleorofmultiplespecificcentresbeadopted，similarityoforganiccontentscannotpossiblyaffordanyproofofthesynchronyofthedepositswhichcontainthem；onthecontrary，itisdemonstrablycompatiblewiththelapseofthemostprodigiousintervalsoftime，andwiththeinterpositionofvastchangesintheorganicandinorganicworlds，betweentheepochsinwhichsuchdepositswereformed。
OnwhatamountofsimilarityoftheirfaunaeisthedoctrineofthecontemporaneityoftheEuropeanandoftheNorthAmericanSiluriansbased？InthelasteditionofSirCharlesLyell’s’ElementaryGeology’
itisstated，ontheauthorityofaformerPresidentofthisSociety，thelateDanielSharpe，thatbetween30and40percent。ofthespeciesofSilurianMolluscaarecommontobothsidesoftheAtlantic。Bywayofdueallowanceforfurtherdiscovery，letusdoublethelessernumberandsupposethat60percent。ofthespeciesarecommontotheNorthAmericanandtheBritishSilurians。Sixtypercent。ofspeciesincommonis，then，proofofcontemporaneity。
Nowsupposethat，amillionortwoofyearshence，whenBritainhasmadeanotherdipbeneaththeseaandhascomeupagain，somegeologistappliesthisdoctrine，incomparingthestratalaidbarebytheupheavalofthebottom，say，ofSt。George’sChannelwithwhatmaythenremainoftheSuffolkCrag。Reasoninginthesameway，hewillatoncedecidetheSuffolkCragandtheSt。George’sChannelbedstobecontemporaneous；althoughwehappentoknowthatavastperiod（eveninthegeologicalsense）oftime，andphysicalchangesofalmostunprecedentedextent，separatethetwo。
Butifitbeademonstrablefactthatstratacontainingmorethan60or70percent。ofspeciesofMolluscaincommon，andcomparativelyclosetogether，mayyetbeseparatedbyanamountofgeologicaltimesufficienttoallowofsomeofthegreatestphysicalchangestheworldhasseen，whatbecomesofthatsortofcontemporaneitythesoleevidenceofwhichisasimilarityoffacies，ortheidentityofhalfadozenspecies，orofagoodmanygenera？
Andyetthereisnobetterevidenceforthecontemporaneityassumedbyallwhoadoptthehypothesisofuniversalfaunaeandflorae，ofauniversallyuniformclimate，andofasensiblecoolingoftheglobeduringgeologicaltime。
Thereseems，then，noescapefromtheadmissionthatneitherphysicalgeology，norpaleontology，possessesanymethodbywhichtheabsolutesynchronismoftwostratacanbedemonstrated。Allthatgeologycanproveislocalorderofsuccession。Itismathematicallycertainthat，inanygivenverticallinearsectionofanundisturbedseriesofsedimentarydeposits，thebedwhichlieslowestistheoldest。Inmanyotherverticallinearsectionsofthesameseries，ofcourse，correspondingbedswilloccurinasimilarorder；but，howevergreatmaybetheprobability，nomancansaywithabsolutecertaintythatthebedsinthetwosectionsweresynchronouslydeposited。Forareasofmoderateextent，itisdoubtlesstruethatnopracticalevilislikelytoresultfromassumingthecorrespondingbedstobesynchronousorstrictlycontemporaneous；andtherearemultitudesofaccessorycircumstanceswhichmayfullyjustifytheassumptionofsuchsynchrony。Butthemomentthegeologisthastodealwithlargeareas，orwithcompletelyseparateddeposits，themischiefofconfoundingthat\"homotaxis\"or\"similarityofarrangement，\"which’can’bedemonstrated，with\"synchrony\"or\"identityofdate，\"forwhichthereisnotashadowofproof，undertheonecommontermof\"contemporaneity\"becomesincalculable，andprovestheconstantsourceofgratuitousspeculations。
Foranythingthatgeologyorpaleontologyareabletoshowtothecontrary，aDevonianfaunaandfloraintheBritishIslandsmayhavebeencontemporaneouswithSilurianlifeinNorthAmerica，andwithaCarboniferousfaunaandflorainAfrica。GeographicalprovincesandzonesmayhavebeenasdistinctlymarkedinthePaleozoicepochasatpresent，andthoseseeminglysuddenappearancesofnewgeneraandspecies，whichweascribetonewcreation，maybesimpleresultsofmigration。
Itmaybeso；itmaybeotherwise。Inthepresentconditionofourknowledgeandofourmethods，oneverdict——\"notproven，andnotprovable\"——mustberecordedagainstallthegrandhypothesesofthepaleontologistrespectingthegeneralsuccessionoflifeontheglobe。
Theorderandnatureofterrestriallife，asawhole，areopenquestions。Geologyatpresentprovidesuswithmostvaluabletopographicalrecords，butshehasnotthemeansofworkingthemintoauniversalhistory。Issuchauniversalhistory，then，toberegardedasunattainable？Areallthegrandestandmostinterestingproblemswhichofferthemselvestothegeologicalstudentessentiallyinsoluble？IsheinthepositionofascientificTantalus——doomedalwaystothirstforaknowledgewhichhecannotobtain？Thereverseistobehoped；
nay，itmaynotbeimpossibletoindicatethesourcewhencehelpwillcome。
Incommencingtheseremarks，mentionwasmadeofthegreatobligationsunderwhichthenaturalistliestothegeologistandpaleontologist。
Assuredlythetimewillcomewhentheseobligationswillberepaidtenfold，andwhenthemazeoftheworld’spasthistory，throughwhichthepuregeologistandthepurepaleontologistfindnoguidance，willbesecurelythreadedbythecluefurnishedbythenaturalist。
Allwhoarecompetenttoexpressanopiniononthesubjectare，atpresent，agreedthatthemanifoldvarietiesofanimalandvegetableformhavenoteithercomeintoexistencebychance，norresultfromcapriciousexertionsofcreativepower；butthattheyhavetakenplaceinadefiniteorder，thestatementofwhichorderiswhatmenofsciencetermanaturallaw。Whethersuchalawistoberegardedasanexpressionofthemodeofoperationofnaturalforces，orwhetheritissimplyastatementofthemannerinwhichasupernaturalpowerhasthoughtfittoact，isasecondaryquestion，solongastheexistenceofthelawandthepossibilityofitsdiscoverybythehumanintellectaregranted。Buthemustbeahalf—heartedphilosopherwho，believinginthatpossibility，andhavingwatchedthegiganticstridesofthebiologicalsciencesduringthelasttwentyyears，doubtsthatsciencewillsoonerorlatermakethisfurtherstep，soastobecomepossessedofthelawofevolutionoforganicforms——oftheunvaryingorderofthatgreatchainofcausesandeffectsofwhichallorganicforms，ancientandmodern，arethelinks。Andthen，ifever，weshallbeabletobegintodiscuss，withprofit，thequestionsrespectingthecommencementoflife，andthenatureofthesuccessivepopulationsoftheglobe，whichsomanyseemtothinkarealreadyanswered。
Theprecedingargumentsmakenoparticularclaimtonovelty；indeedtheyhavebeenfloatingmoreorlessdistinctlybeforethemindsofgeologistsforthelastthirtyyears；andif，atthepresenttime，ithasseemeddesirabletogivethemmoredefiniteandsystematicexpression，itisbecausepaleontologyiseverydayassumingagreaterimportance，andnowrequirestorestonabasisthefirmnessofwhichisthoroughlywellassured。Amongitsfundamentalconceptions，theremustbenoconfusionbetweenwhatiscertainandwhatismoreorlessprobable。*But，pendingtheconstructionofasurerfoundationthanpaleontologynowpossesses，itmaybeinstructive，assumingforthenoncethegeneralcorrectnessoftheordinaryhypothesisofgeologicalcontemporaneity，toconsiderwhetherthedeductionswhichareordinarilydrawnfromthewholebodyofpaleontologicfactsarejustifiable。