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lower end, where it is rather sharp, is there a slight depression for the articu- 

 lation of a sesamoid bone. 



The distal articular surface of the fifth metacarpal (m 5) is reduced to a small, 

 vertical, oblong, nearly flat surface, below which is a convex surface for a sesa- 

 moid bone ; the surface for the digital phalanx is on the radial side of the distal 

 end, the rest of which forms a rough irregular tuberosity, the sharp margins of 

 which overhang the smooth shaft of the bone. The articular surface at the 

 proximal end of the fifth metacarpal is confined to the radial half of the base, which 

 is obliquely truncated : the rest forms part of a rough, flattened protuberance 

 on the ulnar side of the proximal expansion : the opposite side of this presents 

 the flat articulation for the fourth metacarpal. The under surface of the fifth 

 metacarpal is rough at its proximal half, and smooth in the rest of its extent, 

 the two surfaces being divided by an oblique ridge running nearly parallel with 

 that which bounds the distal protuberance: these two ridges include a wide 

 oblique channel. 



Phalanges. — The metacarpal bone of the thumb supports two phalanges ; the 

 first presents a slight and simple articular concavity at its proximal end, which is 

 produced downwards to form the small articulations for the sesamoid bones. The 

 distal articulation is a trochlea with a median vertical channel between two 

 parallel convexities for the ginglymoid joint of the second phalanx. This is a 

 very rugged bone consisting principally of an osseous sheath, extending from the 

 proximal half of the upper part of the bone and the margins of the under and 

 lateral parts of the base : this sheath arches over the upper and lateral parts of 

 the base of the supporting process of the claw, which is a short oblique, sub- 

 compressed cone with a sharp superior margin. The base of this ungual phalanx 

 is excavated by a deep double trochlear articular surface ; and the under part of 

 the base of the sheath is perforated by two large vascular foramina. 



The second digit has three phalanges, of which the terminal one is also mo- 

 dified for the support of a long and strong claw, and is double the size of the 

 preceding ungual phalanx. The proximal phalanx is very short in most Eden- 

 tata, but is unusually so in the present subject, the vertical breadth being 

 double the length of the bone. Both articular surfaces of this phalangeal 

 plate are concave transversely along their middle part ; the proximal one being 

 slightly convex in the same direction on each side, while the distal surface is 



