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  <import namespace="http://xbrl.sec.gov/sic/2011-01-31" schemaLocation="http://xbrl.sec.gov/sic/2011/sic-2011-01-31.xsd"/>
  <import namespace="http://xbrl.sec.gov/stpr/2011-01-31" schemaLocation="http://xbrl.sec.gov/stpr/2011/stpr-2011-01-31.xsd"/>
  <element name="AccruedResearchAndDevelopmentExpenseCurrent" id="zfgn_AccruedResearchAndDevelopmentExpenseCurrent" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="AccruedRestructuringCostsCurrent" id="zfgn_AccruedRestructuringCostsCurrent" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="AdditionalOfficeSpaceMember" id="zfgn_AdditionalOfficeSpaceMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="AdditionalOfficeSpaceTwoMember" id="zfgn_AdditionalOfficeSpaceTwoMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="CommercialPaperNotIncludedWithCashAndCashEquivalentsDueWithinOneYearMember" id="zfgn_CommercialPaperNotIncludedWithCashAndCashEquivalentsDueWithinOneYearMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="CorporateDebtSecuritiesDueAfterOneYearThroughTwoYearsMember" id="zfgn_CorporateDebtSecuritiesDueAfterOneYearThroughTwoYearsMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="CorporateDebtSecuritiesDueWithinOneYearMember" id="zfgn_CorporateDebtSecuritiesDueWithinOneYearMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="DocumentAndEntityInformationAbstract" id="zfgn_DocumentAndEntityInformationAbstract" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="EffectiveTaxIncentiveRateRelatedToResearchAndDevelopment" id="zfgn_EffectiveTaxIncentiveRateRelatedToResearchAndDevelopment" type="num:percentItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="FinancialCovenantsUnderCreditFacility" id="zfgn_FinancialCovenantsUnderCreditFacility" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="FollowOnOfferingMember" id="zfgn_FollowOnOfferingMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="IncreaseDecreaseInTaxIncentivesReceivable" id="zfgn_IncreaseDecreaseInTaxIncentivesReceivable" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="LicensingFeesPerProductMaximum" id="zfgn_LicensingFeesPerProductMaximum" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="MilestonePaymentAmount" id="zfgn_MilestonePaymentAmount" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="NonCashMember" id="zfgn_NonCashMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="NotesPayableNetOfCurrent" id="zfgn_NotesPayableNetOfCurrent" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="OfficeSpaceLeaseMember" id="zfgn_OfficeSpaceLeaseMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="OperatingLeasesNumberOfOptionsToExtendLease" id="zfgn_OperatingLeasesNumberOfOptionsToExtendLease" type="xbrli:integerItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureLineItems" id="zfgn_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureLineItems" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTable" id="zfgn_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTable" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrldt:hypercubeItem"/>
  <element name="PercentageReductionResearchAndDevelopmentCosts" id="zfgn_PercentageReductionResearchAndDevelopmentCosts" type="num:percentItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="PreCommercializationMilestonesMember" id="zfgn_PreCommercializationMilestonesMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="PremiumOnMarketableSecurities" id="zfgn_PremiumOnMarketableSecurities" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="ProductCommercializationMilestonesMember" id="zfgn_ProductCommercializationMilestonesMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="ResearchAndDevelopmentExpensesTable" id="zfgn_ResearchAndDevelopmentExpensesTable" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrldt:hypercubeItem"/>
  <element name="ResearchAndDevelopmentTaxIncentiveLineItems" id="zfgn_ResearchAndDevelopmentTaxIncentiveLineItems" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="SubsequentLicensedProductMember" id="zfgn_SubsequentLicensedProductMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="TaxIncentiveReceivable" id="zfgn_TaxIncentiveReceivable" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="TaxIncentiveReceivableCurrent" id="zfgn_TaxIncentiveReceivableCurrent" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="TaxIncentiveReceivableNoncurrent" id="zfgn_TaxIncentiveReceivableNoncurrent" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="TaxIncentiveResearchAndDevelopmentActivities" id="zfgn_TaxIncentiveResearchAndDevelopmentActivities" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="TwoThousandAndFourteenCreditFacilityMember" id="zfgn_TwoThousandAndFourteenCreditFacilityMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="TwoThousandFourteenStockOptionMember" id="zfgn_TwoThousandFourteenStockOptionMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="UnvestedRestrictedCommonStockUnitsMember" id="zfgn_UnvestedRestrictedCommonStockUnitsMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="UsGovernmentSecuritiesDueWithinOneYearMember" id="zfgn_UsGovernmentSecuritiesDueWithinOneYearMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="UsGovernmentSecuritiesMember" id="zfgn_UsGovernmentSecuritiesMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
</schema>





