New gastropods from the Maastrichtian of the Mexcala Formation in Guerrero, southern Mexico, part II: Archaeogastropoda, Neritimorpha and Heterostropha. Neues Jahrbuch fuer Geologie und Palaeontologie Abhandlungen, 226(3), Dezember 2002: 319-342. 328 [Zoological Record Volume 139]