52 PATAGONIAN EXPEDITIONS! PALAEONTOLOGY. 



scaphoid is broad, but very short proximo-distally, and has the external 

 angle produced obliquely downward between the lunar and trapezoid to 

 a contact with the magnum ; the distal end is almost all occupied by the 

 large facet for the trapezoid, internal to which is a much smaller one for 

 the trapezium. The lunar is narrow on the dorsal side, much broader on 

 the palmar ; the facet for the radius is convex, descending well upon the 

 dorsal face ; this bone rests principally upon the extension of the scaphoid, 

 but also covers the proximal end of the magnum and has a narrow con- 

 tact with the unciform. The pyramidal is very broad and receives a 

 peculiar appearance from its numerous articular surfaces ; the ulnar facet 

 is broad transversely, narrow palmo-dorsally, and posterior to it is the 

 large, almost plane facet for the pisiform ; on the distal side is a large, 

 concave facet for the unciform and external to this, a prominent projec- 

 tion which articulates with metacarpal V. The pisiform is not unlike that 

 of Dasypus, but relatively longer ; it is laterally compressed and curved 

 and tapers to a blunt point at the free end, while the other end is broad- 

 ened to form the large facets for the ulna and pyramidal. 



The trapezium is long, narrow and quite thick, widening somewhat at 

 the distal end ; its articulation with the scaphoid is lateral rather than 

 proximal, and distally it extends somewhat below the trapezoid, so as to 

 reach metacarpal II. The trapezoid is short, but very broad, occupying 

 nearly the full width of the scaphoid ; dorsally, it has little or no contact 

 with the trapezium, but articulates with metacarpal III. The magnum is 

 the smallest bone of the distal row, its dorsal face is nearly square, with 

 rounded angles ; proximally, it articulates with the scaphoid and lunar, 

 distally, only with metacarpal III. The- unciform is quite large and its 

 dorsal face is wedge-shaped, thinning away to the ulnar side ; it is much 

 narrower than the pyramidal, but longer proximo-distally. 



As in all the recent armadillos, there is a very large palmar sesamoid 

 which is broader and has a more regularly oval shape than that of 

 Dasypus. 



The metacarpals are relatively much stouter than in Dasypus ; in order 

 of length the arrangement is III, II, IV, I, V, but this order is not that 

 of the complete digits, the phalanges of the second digit more than com- 

 pensating for its shorter metacarpal and giving the order, II, III, IV, I, V. 



Metacarpal I is much the most slender of the series ; the proximal end 

 is rather broad, the shaft narrowing to the distal end, which slightly 



