Bull. Florida St. Mus., Biol. Sci. 20(4): 187-300. 8 tabs. 39 figs. July 9, 1976.

–The material on Metaxytherium ossivallense is revised from Reinhart's Master of Science thesis in Geology (Univ. of Chicago, Dec. 1947). Synonymizes Felsinotherium and Halianassa with Metaxytherium and reviews their morphology (191-199). Recognizes M. ossivallense, M. floridanum, M. calvertense, and Hesperosiren crataegensis in the Mioc. of Florida, and describes new material referred to each (199-235). Describes Halitherium olseni, n.sp. (Mioc., Florida; 238-261; now considered Late Olig.). Reports Eoc. rib fragments from Florida (262-265); discusses fossil sir. records from Java and Australia (266-269); describes vestigial incisors in Dugong dugon (269-272); and reports a tooth of Metaxytherium sp. indet. from the Mioc. of Argentina (272-278). Discusses trichechid phylogeny (279-281), "Manatus" maeoticus (281-282), Cryptomastodon (282-283), valid and invalid records of desmostylians from Alaska, Florida, and Texas (283-287), and new specimens of Desmostylus hesperus (288-295). Morgan (1994: 264-265) concluded that the Florida Desmostylus specimens reported here have erroneous locality data and are really from California.