﻿FELIS SPELiEA. 135 



or anterior surface of the proximal end runs diagonally a shallow groove (PL XXI, fig. 2, e), 

 to the upper part of which is attached the trapezoidal ligament. The whole of the head 

 of the bone is roughened for the reception of the ligaments binding the bone to the carpus 

 and its fellow metacarpals. The shaft presents a triangular section proximally, and is 

 nearly circular in the middle and distally. At the point where it joins the distal articu- 

 lation it is flattened in front, and develops a slight palmar ridge behind. 



The distal articulation of the four outer metacarpals (Pis. XIX, fig. 6 ; XX, fig. 7; XXI, 

 figs. 2, 3, 4, 5,/) bear a strong resemblance to each other; like those of the metatarsals 

 they are bulb-shaped, and divided from the epiphysial line of the shaft by deep dorsal and 

 lateral depressions (y) ; on the palmar or inferior surface they develop a short ridge in 

 the median line (PI. XX, fig. 7), which fits into the palmar notch of the first phalanges. 

 On either side of it lies a sesamoid bone to which are fixed nearly all the tendons of the 

 adductor and flexor muscles, for the movement of the metacarpals. At the point where 

 the shaft joins the distal end is a tuberosity (PI. XXI, figs. 2, 3, 4, 5, i) which catches the 

 sides of the phalangeal articulations, and prevents these bones from bending backwards 

 beyond an angle of about 60°, and thus forms a firm fulcrum for the support of the weight 

 of the body. 



The distal terminations of the metacarpals may easily be distinguished from each 

 other by the positions of the tuberosities, and by the form of the distal articulations. 

 The distal articulation of the fifth is, as it were, cut off on the outer side (PI. XXI, fig. 5,/), 

 while that of the second (fig. 2/) is cut off on the inner side : the third and fourth are 

 symmetrica], the former having the inner, and the latter the outer, tuberosity larger, and 

 set lower on the bone. These articulations are epiphysial. 



The proximal articulation of the third metacarpal (fig. 3) is set nearly at right angles 

 to the end of the shaft, the dorsal face expanding considerably more than the posterior ; 

 it is vertically convex, transversely concavo-convex. On its inner side is a broad oval 

 surface (fig. 3, a) set on a tuberosity for articulation with the overhanging portion of the 

 second metacarpal (fig. 2, d) ; these two articular surfaces are divided from each other by a 

 well-marked ridge (c). On the external side are two concave surfaces (fig. 3, e), which 

 overhang and articulate with the fourth metacarpal : they are not so deeply concave, and 

 are more confluent than those of the second. The proximal dorsal surface of the fourth 

 (fig. 4) strongly resembles that of the third, but it is rounder and less excavated ; the 

 articulation also is altogether different, the facet for the unciform (fig. 4 d) being simply 

 convex vertically and flat transversely, while that for the third metacarpal and the os 

 magnum forms a continuous surface (fig. 4 a), partially interrupted on the inner side by a 

 ligamentary notch (PI. XX, fig. 6). It is slightly convex both vertically and transversely, 

 and usually forms one curvilinear surface with the unciform articulation, being divided 

 from it by a slight ridge. This form from Bleadon is shown in PL XX, fig. 6. In 

 that figured in PL XXI, fig. 4, these surfaces (d, a) are set at a considerable angle to 

 each other ; these two bones represent the extreme variation in the form of the proximal 



