399px-Boundary_lines_of_British_Guiana_1896
This map shows the Boundary lines of British Guiana on the map of Scottish Geographical Magazine, 1896 (page 88). Map by the Edinburgh Geographical Institute & John George Bartholomew – “Cartographer to the King” (1860-1920). A useful map for collectors and postal historians of British Guiana.

Courtesy Wiki Commons maps.