ABSTRACT Decapod crustaceans from the Mesozoic of Madagascar have been studied by a number of authors during the last century. One of the largest sets of specimens was collected by the French General Maurice Collignon between 1930 and 1950; this was subsequently studied by Secretan (1964) who described numerous species of macrurans, brachyurans, and axiideans. These crustaceans originate from the Upper Jurassic and the Upper Cretaceous of the Mahajanga Basin (NW Madagascar) and, especially, from the Morondava Basin (central-SW Madagascar). The purpose of the present study is twofold: to furnish an update of the stratigraphy and geology of the studied areas and, above all, to revise the Secretan's species, employing current systematic nomenclature, supplying for each detailed geographic and stratigraphic data since such were either cursory or incomplete in previous papers. The present revision considers 13 species recorded by Secretan as valid, namely: Enoploclytia collignoni Secretan, 1964, Eryma granulif...