THE FORE FEET. 127 



Thj: Fifth Metacarpal. (Plate XXXVII, figures 4-9.) 



The specimens of the iitth metacarpal in the Yale Museum are, 

 unfortunately, all more or less distorted b}' pressure, and hence fail to 

 fully represent this element of tlie manus. The bone is well developed, 

 scarcely smaller than the third and fourth, and considerably surpasses the 

 first in lenyth. Like the other bones of the metacarpal series, it is rough 

 and tubercular, especially toward the ends. 



The proximal end (Plate XXXVII, figure 8) presents three articular 

 faces, of which the main and middle one, for the support of the bone upon 

 the unciform, is strongly convex. The convexity is carried through a 

 considerable arc in the antero-posterior direction, to correspond with the 

 outer, and most concave facet, on the unciform bone, to which it is adapted. 

 This su!-face is bordered, on the inner, or radial side, by a face, broadest 

 anteriorly, for motion on the fourth metacarpal. Behind, and on the outer, 

 or ulnar, side of the principal articular face, is a much smaller face, which, 

 in life, moved upon a corresponding articulation on the distal end of the 

 pyramidal. 



In some specimens, the shape of the unciform, as shown on page 

 119, figure 124, would seem to make this impossible, and doubtless this 

 face will not be found to be constantly present on the fifth metacarpal. 



The distal end of the bone (Plate XXXVII, figure 9) presents, as 

 usual, a round, or oval, face for articulation with the phalanx, and sliallow 

 grooves below for a pair of sesamoids. 



The specimens preserved are so much distorted that measurements 

 would be of comparatively little value. 



The Phalanges. (Plate XXXVIII, and Plate LIV, figm-e 1.) 



The i)halanges in the fore foot of the iJinocerata are very short, and 

 comparatively ''small. Their general characters ai'e shown in the Plates 

 cited above, as well as in the restorations given in Plates LV and LVI. 



