DAKOTA AND NEBRASKA. 259 



nous to the soil. These facts appear the more remarkable in view of the circum- 

 stance that several species of Equus, and species of closely allied genera, existed in 

 America during former geological periods, and became subsequently extinct. 



Fossil remains, referred to several species of Equvs, have been discovered in the 

 post-tertiary deposits of South America. 



Mr. Darwin, in his Journal of the Voyage of the Adventure and Beagle, vol. iii, 

 pp. 96, 149, 1839, gives an account of his discovery of two fossil teeth of a species of 

 Equus in Bahia Blanca and Eutre Rios. These specimens, found in the same forma- 

 tion as remains of extinct Edentata, of Toxodon and Mastodon, and in the same con- 

 dition of preservation, were subsequently described by Prof. Owen, in the Zoology of 

 the Voyage of the Beagle, Fossil Mammalia, page 108, 1840. Of one of them he 

 observes : " Every point of comparison that could be established proved it to differ 

 from the tooth of the common Equus cahallus only in a slight inferiority of size." Of 

 the other, which is represented in figures 13, 14, of plate xxxii, accompanying the 

 work, by the comparison of which with the teeth of the Horse, the author remarks : 

 " The anatomist can judge of its close correspondence vdth a middle molar of the left 

 side of the upper jaw." Later, in the Catalogue of the Fossils of the Museum of the 

 Royal College of Surgeons, page 236, 1845, Prof. Owen refers the two fossil teeth to 

 an extinct species, under the name of Equus curvidens, and of the specimen, figured 

 in the work before quoted, he observes : " It has a greater relative antero-posterior 

 diameter than in the recent Horse, but difiers more especially in the greater degree 

 of incurvation of the entire tooth." 



Dr. Lund, in a letter from Brazil, April 1, 1840, to the Editors of the Annales des 

 Sciences Naturelles, 2d series, vol. 13, p. 319, 1840, stated that he had found the 

 metatarsal bone of a species of Equus in the midst of an osseous breccia, including 

 bones of the extinct Canis troglodytes, Dasypus pundatus, and Chlamydotherium 

 Humholdtii. He says, " the bone is broader and more flat than those of the living 

 Horses with which he had the opportunity of comparing it," and refers it to an ex- 

 tinct species with the name of Equus neogceus. 



In the Transactions of the Royal Danish Academy of Sciences, vol. 12, pp. 89, 93, 

 plate xlix, 1840, Dr. Lund indicates and figures five teeth, from bone-caverns of 

 Brazil, which are referred to three species of Equus, including that last designated ; 

 the additional ones being named Equvs principalis and Equus cahallus. 



According to M. Gervais, Weddell, in his Voyage dans la Bolivie, page 204, which 

 work I have not seen, indicates remains of an extinct Horse, which he refers to a 

 species with the name of Equus macrognathus. M. Gervais himself, in Gay's Historia 

 de Chile, Zoologia, vol. 1, p. 146, plate viii, figure 7, 1847, describes and figures an 

 inferior molar of robust proportions, which he refers to a species with the name of 



