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THE AUEIFEKOTTS GEAYELS OF THE SIEBEA NEVADA. 



as has been repeatedly noticed to be the case with the mastodon remains. 

 Further remarks on this point and on the probable relative geological age of 

 the mastodon and elephant may be found in the following section. 



Next to those of the mastodon and elephant, the most abundant fossil 

 remains found in the gravel region are those of the horse, and of this animal 

 several species have been recognized by Dr. Leidy among the specimens col- 

 lected from different parts of the State and submitted to him by the Geologi- 

 cal Survey. It seems proper to publish in fall the notes furnished by him 

 in regard to the equine remains examined, although some years have elapsed 

 since they were written. These notes do not appear to have been rendered 

 any the less valuable by what has since been published on this subject. They 

 will be followed by some general remarks on the probable geological position 

 of the different species mentioned, which will be introduced when discussing 

 the age of the human remains discovered in the same deposits with the 

 various animals which have been described. 





Equus excelsus. Leidy : Proc. Ac. Nat. Sci., Phila. 1858, 26. 



Equus occidentalis. Leidy : Ibidem, 1862, 94. 



An extinct species supposed to be different from other North American species, and about the 

 size of ordinary varieties of the recent domestic horse. It is indicated by the following specimens : 



a. The greater portions of both jaws of an individual of mature age. The specimens are thor- 

 oughly imbued with bitumen, and were obtained near Buena Vista Lake.* 



The portions of the upper jaw contain the incisors, canines, and the anterior four large molars 

 of the left side. The teeth, resemble in their size and relationship those of the living horse. The 

 course of the enamel lines on the triturating surfaces of the molars presents an extreme condition 

 of simplicity. The bottom of the principal internal valley is devoid of the inflection of enamel 

 seen in the recent horse, and in this respect the fossil teeth resemble more those of the ass. 



The portions of the lower jaw contain all the teeth of both sides except one last molar. The 

 teeth present nothing peculiar distinguishing them from those of the recent horse. 



b. Portion of the left ramus of a lower jaw of another individual from the same locality. It 

 belonged to an older but somewhat smaller animal, and like the preceding specimens is imbued 

 with bitumen. It contains the anterior five molars. 



c. An isolated upper molar, from the same locality and in the same condition. It exhibits the 

 peculiarities already mentioned in the scries of upper molars. (>' ■ 



The collection of the Academy of Natural Science also contains a portion of an upper jaw 

 with the anterior five molars, from the same locality and in the same condition, presented by 

 Dr. George II. Horn. The teeth likewise exhibit the peculiarities above mentioned, distinguishing 

 them from those of the recent horse. 



d. An isolated upper molar, from auriferous clay, twenty feet below the surface, Columbia, 

 Tuolumne County. It is a second of the series, is hardly changed in texture, and is only partially 

 stained with iron. The tooth exhibits the same peculiarities as the upper molars above indicated. 



,/ e. Two upper molars, from different individuals, with no locality indicated [but probably from 

 Sonora]. They both exhibit the peculiarities above mentioned* 



* The exact locality is believed to be the "Sta. Maria Oil Springs," about twelve miles northwest of 

 the north end of Buena Vista Lake. 



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