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.
The writer has examined a large canine tooth found in the stratum of sand, No. 2. From its size it is referred to Equus complicatus. Its fore-and-aft diameter is 14 mm. Another tooth from the stratum, an upper right third true molar, finely preserved and retaining some of the cement, is regarded as belonging to E. leidyi. Two lower teeth from No. 2 are water-worn, but retain their structure. The fore-and-aft diameter of each is 21 mm. They must have belonged to the little horse called E. littoralis. A fragment of an upper tooth is referred to this species. It is not water-worn, but has been split from the crown to the root. A hinder first phalangeal bone found in the canal (No. 1802 of the Florida Geological Survey) is 96 mm. long. This indicates a horse as large as our ordinary domestic horses and it probably belonged to Equus complicatus.
22. Labelle, Lee County.—In 1889 (Trans. Wagner Inst., vol. II, p. 17), Leidy stated that Mr. Joseph Willcox had obtained, from a Pliocene shell-bed on Caloosahatchee River, some remains of a fossil horse, consisting of two cervical vertebræ and a part of a lower jaw, which contained the first and second molar teeth. These teeth are probably what would be called premolars 2 and 3. Leidy referred the remains to his Equus fraternus (=E. leidyi).
Dall (Bull. No. 84, U. S. Geol. Surv., p. 129) stated that Equus fraternus, Bison latifrons, and Elephas columbi were found in Pliocene beds on the Caloosahatchee, but Sellards (8th Rep. Florida Geol. Surv., p. 102) corrects this error as to the age.
The writer has received a letter from Mr. Willcox in which he states that the fragment of lower jaw was found about 2 or 3 miles below Labelle.
23. Palm Beach, Palm Beach County.—In 1916 (8th Ann. Rep. Florida Geol. Surv., p. 105), Sellards wrote that Mr. J. L. Hayes had secured for the Florida State Geological Survey, from the Palm Beach Canal, teeth of Elephas columbi and Equus complicatus and a femur of a species of Bison.