EQUINE FOSSILS.— Leidy. 103 



A similar blackened tooth, represented in figure 6, Plate XV, was obtained from the same 

 formation, at Doctor's Swamp, John's Island. 



Figures 2-5, represent four superior molars of the extinct Horse, from the Post-Pleio- 

 cene bed of the Ashley river, all exhibiting a greater complexity of the enamel folding 

 than is the case in the recent Horse. These specimens are hard, brown in color, and 

 range from two, to about three and a half inches in length, and measure from one inch two 

 lines, to one and a quarter inches in antero-posterior diameter, and from one inch, to one 

 inch and two lines in transverse diameter. 



Figure 7, Plate XV, represents a last upper molar of the right side, also from the Post- 

 Pleiocene bed of the Ashley river. The specimen is dense, brown in color, and well 

 preserved, except having lost its exterior cement. Its enamel folding is quite complex ; 

 and it measures two and a quarter inches in length, sixteen lines in antero-posterior 

 diameter, and eleven lines transversely. 



The Museum of the Academy of Natural Sciences, of Philadelphia, contains a number 

 of teeth of the extinct Horse, of which six upper and seven lower molars were found in 

 association with remains of Mastodon, Elephas, Megalonijx, Mylodon, Ereptodon, Bison 

 latifrons, Ursus, Felis atrox, etc., in ravines in the vicinity of Natchez, Mississippi ; two 

 upper molars, were obtained by Dr. Dickeson from one of the islands of the Mississippi, 

 near Natchez ; and an inferior molar was found in association with remains of Mastodon, 

 Elephas, Megatherium, etc., in the excavation of the Brunswick canal, near Darien, Georgia. 



The teeth from the vicinity of Natchez are usually well preserved, except that they are 

 generally deprived of their exterior cement, and the dentine is more or less friable. They 

 vary considerably in point of comparative size and degree of complexity. 



Figures 24-26, Plate XVI, represent specimens of inferior molars of the extinct Horse, 

 obtained by Dr. Dickeson from the ravines of Natchez. They vary from two and a half, 

 to four and a quarter inches in length, thirteen and a half, to fifteen lines in breadth, and 

 six and a half, to eight lines in width. The tooth represented by figure 25, appears to 

 have belonged to the temporary series, which are larger than their permanent successors. 



Figure 27 represents an inferior fourth molar, which, with a portion of the jaw and the 

 impress of the third, fifth, and sixth molars, are preserved in a thick fragment of compact 

 peroxide of iron. The specimen, together with an upper molar of the same animal, and a 

 portion of the lower jaw of Felis atrox, similarly preserved, were obtained by W. H. 

 Huntington, Esq., from the vicinity of Natchez, and presented to the American Philo- 

 sophical Society. The fourth molar, above referred to, is about three and three-quarter 

 inches long, and does not differ from its correspondent in the recent Horse. 



Figures 11-15, Plate XV, represent specimens of superior molars, from the Natchez 

 ravines, all with the enamel more complexly folded than in the corresponding teeth of the 

 domestic Horse, as may be seen by comparing them with figure 1, representing the upper 

 molar series of the latter. Figure 13, apparently represents an upper molar of the tempo- 

 rary series. The others measure three and a half, to three and three-quarter inches long ; 

 fourteen, to sixteen lines broad ; and twelve, to fourteen lines wide. 

 27 



