20. _Arcadia, De Soto County._—Many remains of horses, especially teeth, have been collected at and near this place, by Mr. Joseph Willcox, on a sand-bar at Arcadia being explored for phosphate. The first published description of these remains appears to be that of Leidy in 1889 (Trans. Wagner Inst., II, p. 19). Leidy had at hand 17 upper molars, 2 lower molars, and 2 incisors. He was, at that time, uncertain whether these teeth pertained to an indigenous species of _Equus_ or to the domestic horse. The manager of the Arcadia Phosphate Company, Mr. T. S. Moorhead, informed Mr. Willcox that the main source of the materials of the bar extended for miles along the shores of Peace Creek and was about 8 feet thick. Among the materials examined by Leidy (Proc. Acad. Nat. Sci. Phila., 1890, p. 182) was a tooth which he regarded as belonging to _Equus major_ (=_E. complicatus_), but, on the suggestion of Professor Cope, he described and figured as _Hippotherium princeps_. Later, Lucas (Trans. cit., vol. IV, p. 49, plate XIX, figs. 12, 13) concluded that Leidy’s first opinion was correct. The tooth is abnormal in having the column of the protocone free from the other cusps of the tooth for a short distance from the grinding-surface. In Bulletin No. 84 (p. 129) of the U. S. Geological Survey, Leidy referred the Peace Creek horses to his _Equus fraternus_ (=_E. leidyi_), and it is found that in size and other respects the type of _Hippotherium princeps_ agrees with this species. It is retained, however, as _Equus princeps_. In the U. S. National Museum are 6 teeth collected on Peace Creek, probably not far from Arcadia, which all apparently belong to E. leidyi. J. W. Gidley (Bull. Amer. Mus. Nat. Hist., vol. XIV, 1901, p. 121) stated that there is in the American Museum a tooth from Peace Creek, much too small to be referred to any species at that time reported from the United States, but resembling closely _Equus tau_, from Mexico. This tooth probably belongs to _Equus littoralis_. Besides the horses of the genus _Equus_, there have been found at or near Arcadia the 3–toed horse _Hipparion ingenuum_. Whether this is to be referred with the great majority of the fossils found in this region to the Aftonian fauna of the first interglacial or to the Nebraskan stage it is impossible to say. 21. _Vero, St. Lucie County._—Numerous remains of extinct horses have been found here, but they always consist of single bones or teeth, sometimes in fine condition, sometimes somewhat water-worn. The remains occur in both deposits, designated as No. 2 and No. 3, but in the latter the materials are more fragmentary and not specifically identifiable. Sellards has figured some of the teeth in his seventh Annual Report (1915, pp. 110, 111, figs. 40–43). In his eighth report, on page 149, he has recognized the occurrence here of 3 species, _Equus complicatus_, _E. leidyi_, and _E. littoralis_.