The generic allocation of American soft-shelled turtles has varied considerably in recent years: Smith (_loc. cit._) uses _Platypeltis_; Pope (Turtles of the United States and Canada, p. 343, 1939) uses _Trionyx_ Geoffroy; and Stejneger (_op. cit._, p. 8) uses _Amyda_ Geoffroy. As stated above, use of _Platypeltis_ at the present time is unwarranted, since no constant difference has been discovered that would support generic separation of Asiatic and American members of this group. New World turtles should be placed either in _Trionyx_ or in _Amyda_, depending upon the interpretation of type designation for the latter name. Malcolm Smith (Bull. Raffles Mus. 3:2, 1930) and others have considered that, as a part of the original description, Geoffroy (Ann. Mus. Hist. Nat. Paris, 14:20, 1809) designated the type species of his new generic name _Trionyx_ as _aegypticus_ E. Geoffroy (= _triunguis_ Forskål a well-recognized species). Stejneger argues that Geoffroy did not adequately designate a type from among the many species he treated in his genus _Trionyx_, and that it remained for Fitzinger (Syst. Rept., p. 30, 1843) to select one of these as a type; he chose _coromandelicus_ Geoffroy, which is a synonym of _granosa_ Schöppff, a species belonging to a different genus (as now recognized) from that to which _triunguis_ belongs, although Geoffroy had made the mistake of considering both groups as members of his genus _Trionyx_. Now if Fitzinger's type designation is accepted, the name _Trionyx_ is to be applied to that group containing _granosa_ (only one other form is known in the genus, and both forms occur only in India and Burma), whereas the name _Amyda_ of Geoffroy (_op. cit._, p. 1) is applied to the genus (as now recognized) which includes _triunguis_ and some 20 other species of Asia and North America. The type of _Amyda_ is a typical member from Asia (_cartilagineus_ Boddaert). On the other hand, if Geoffroy's type designation is accepted, the American forms (and the others of that genus) would take the generic name _Trionyx_, of which _Amyda_ would be a synonym, and the genus to which _granosa_ belongs would take the name _Lissemys_ Malcolm Smith (Fauna Brit. India, Rept. Amph., 1:154, 1931).