British Guiana. 1864. stamp-less envelope to France written from Cayenne (French) dated '11 April 64' cancelled on reverse be British Post Office Demerara cds (116/4) endorsed 'via Anglaise' with Anglo-French accountancy 'GB/2f' routed via St Louis, Senegal with London transit and French entry cachet, rated '10' with Marseille receiver. Very rare item of accountancy mail from Guiana.