1817. _Geomys_ Rafinesque, Amer. Monthly Mag., 2(1):45, November. 1817. _Diplostoma_ Rafinesque, Amer. Monthly Mag., 2(1):44-45, November. Included species: _Diplostoma fusca_ Rafinesque [= _Mus bursarius_ Shaw] and _Diplostoma alba_ Rafinesque [= _Mus bursarius_ Shaw] from the Missouri River region. 1820. _Saccophorus_ Kuhl, Beitr. Zool. und Vergl. Anat., pp. 65, 66. Type: _Mus bursarius_ Shaw, from upper Mississippi Valley. 1823. _Pseudostoma_ Say, Long's Expd. Rocky Mts., I, pp. 406. Type: _Pseudostoma bursaria_ [= _Mus bursarius_ Shaw], from upper Mississippi Valley. 1825. _Ascomys_ Lichtenstein, Abh. K. Akad. Wiss. Berlin (1822), p. 20., fig. 2. Type: _Ascomys canadensis_ Lichtenstein [= _Mus bursarius_ Say], probably from upper Mississippi Valley. 1944. _Parageomys_ Hibbard, Bull. Geol. Soc. Amer., 55:735, June. Type: _Parageomys tobinensis_ Hibbard, from Pleistocene, Cudahy (Tobin) local fauna, Russell Co., Kansas. _Type._--_Geomys pinetis_ Rafinesque, 1817, restricted to Screven County, Georgia, in region of the pines. _Chronologic range._--Late Pliocene faunas of Blancan age (Rexroad, Kansas, and Sand Draw, Nebraska, local faunas) to Recent. Reported from numerous Pleistocene deposits of all stratigraphic levels, especially from the Great Plains, where common today. _Description and discussion._--Pocket gophers of this genus are medium-sized geomyids; none is so small as the average-sized _Thomomys_. The skull is generalized and lacks the dolichocephalic and platycephalic specializations seen in the genera _Orthogeomys_ and _Pappogeomys_, respectively. _Geomys_ closely resembles _Zygogeomys_, but retains fewer of the primitive characters of the ancestral stock. At the same time, _Geomys_ has several specializations. Even so, a considerable amount of parallelism is evident in the phyletic trends of the two genera.