DAKOTA AND NEBRASKA. 



271 



varying in size. The largest are about the same size as in the recent Horse ; the 

 smallest perhaps may belong to some of the larger Hiiiparions hereafter to be indicated. 

 Their measurements are as follow : 



Greatest breadth of articular surface of condyles, 

 Width, from before backward, of inner condyle, . 

 Width of outer condyle, . . . , 



Breadth of base, . . . . . 



Breadth of scaphoid articular surface, 

 Greatest depth of do., . . . , 



Extreme length, 

 Depth at middle of tuberosity. 

 Width at middle of tuberosity, 

 Depth of extremity of tuberosity. 

 Thickness of extremity of tuberosity, 

 Depth of articular extremity. 

 Breadth of articular extremity, 



17. A fragment of a calcaneum and an astragalus, picked up by Dr. Hayden on the 

 surface of the ground near Fort Pierre, ou the Missouri River, therefore in a locality 

 remote from where the preceding specimens were obtained. The bones appear to be 

 thoroughly j^etrified or infiltrated with siliceous matter, and have spots of lichens 

 on the surface. They correspond in form and size with the same bones in smaller 

 varieties of the I'ecent Horse. The measurements of the astragalus agree pretty 

 closely with those of the above specimens, indicated in the second and third rows. 



18. A scaphoid bone, from the Niobrara River, about the size and proportions of those 

 of the common Horse. It measures twenty-eight lines from side to side, twenty-two 

 lines from before backward, and six lines in thickness. 



19. A series of four bones, together comprising a complete foot, from the Niobrara 

 River. Though all probably derived from different individuals, they hold the same 

 proportion to one another and agree in size with the corresponding bones of the 

 ordinary Horse. They consist of the left median metatarsal bone and the suc- 

 ceeding phalanges. The entire foot measures nineteen inches in length. 



The metatarsal bone is twelve and a half inches long; its circumference at middle 

 four and three-quarters inches ; the breadth of its proximal end twenty-nine lines, 

 and the antero-posterior diameter twenty-four lines ; the breadth of the distal ex- 

 tremity is twenty-five lines, and the antero-posterior diameter twenty lines. 



