THE FORE FEET. 121 



The First Metacarpal. (Plate XXXV, figm-es 1-6.) 



The metacarpal bone of the first, or inner, digit, the pollex, is a 

 robust, and usuallv short bone, proportionally much stronger than in 

 the elephant. In all the specimens preserved, the epiphyses, whether 

 present on one end only, or on both ends, as in the elephant, are firmly 

 codssified with the shaft of the bone. The surface of the bone, as shown 

 in Plate XXXV, figures 1-4, is rough and very irregular. 



The proximal articular face (figure 5) is nearly elliptical in outline, and 

 is flattened, but elevated, near the middle of the palmar side of the margin. 

 On some specimens, there is a distinct oval face for contact with the 

 second metacarpal. This face is raised upon a large tubercular elevation, 

 and may, or may not, be in contact with the proximal articular face. 



The distal end (figure 6) presents a flattened, and somewhat concave, 

 face for the phalangeal bone, and two broad, oblique grooves for the 

 sesamoids. 



Three first metacarpals of Dinoceras have their principal dimensions 

 as follows : 



Measurements of First Metacarpal. {Dinoceras mirahile, No. 1208.) 



m. 

 Total length of first metacarpal, _ _ .063 



Diameters of proximal articular face (approximate), .025-.044 



Diameters of face for phalanx, 027-.034 



Measurements of First Metacarpal. {Dinoceras mirahile. No. 1211.) 



m. 

 Total length of first metacarpal, ._ _ .098 



Diameters of proximal articular face (approximate), .030-050 



Diameters of face for phalanx, .037-043 



Diameters of face for second metacarpal, 020-.022 



Measurements of First Metacarpal. {Dinoceras, No. 1526.) 



m. 



Total length of first metacarpal, . .056 



Diameters of proximal articular face (npproximate), 026-.044 



Diameter of face for phalanx, ,030 



16 ~ 



