84 PATAGONIAN EXPEDITIONS.: PAL/EONTOLOGY. 



distal trochlea has a much deeper median groove than that of Prozaeditis. 

 Metacarpal III is much longer and stouter, with very deep proximal con- 

 cavity for the magnum and unusually deep pit on the ulnar side for the 

 projection from metacarpal IV ; the distal trochlea is not so much grooved 

 as that of metacarpal IV, but proximal to the trochlea on the dorsal side 

 of the shaft is a large, deep fossa, which receives the "beak" of the first 

 phalanx. Metacarpal IV is hardly more than one half as long as meta- 

 carpal III ; its proximal end is extensively overlapped by the latter, so 

 that only a narrow convexity articulates with the unciform, quite as in 

 Dasypus; this convexity has a more external position than in Prozaediits, 

 giving the proximal end a bifid appearance, instead of the trifid shape seen 

 in the latter. Metacarpal V is extremely short, heavy and of pyramidal 

 shape, less quadrate than that of Dasypus, but otherwise like it. 



The phalanges differ in certain respects from those of any other Santa 

 Cruz armadillo. The proximal phalanx of the pollex is long and slender, 

 like that of Prozaeditis ; in digit II the same phalanx is very long, almost 

 equalling metacarpal II in length ; it is very slender and compressed, 

 though quite heavy at the proximal end, and the distal end is much more 

 deeply grooved than in the preceding genus. The second phalanx of 

 this digit is like the first, but even longer and more compressed, a marked 

 difference from Prozaediiis.^ The ungual is rather small, of symmetrical 

 shape, slender, decurved and pointed ; it is not cleft at the tip and has an 

 uncommonly large subungual process. Despite its small ungual, digit II 

 slightly exceeds III in length. 



In digit III the first and second phalanges are coossified, the only 

 instance of the kind yet observed among the Santa Cruz edentates. A 

 suture yet remains to show that the first is very short, while the second 

 is longer, though hardly half as long as the corresponding phalanx of digit 

 II. The ungual is much the largest in the manus and its great length 

 almost compensates for the shortness of the other two phalanges ; in 

 shape it is unlike that of any other known contemporary armadillo, being 

 narrow, moderately decurved, bluntly pointed and quite asymmetrical ; the 

 ulnar side is convex and curves gradually into the dorsal surface, while 

 the radial side is plane and forms a sharp border along its junction with 

 the dorsal side ; the end is uncleft and the subungual process large. 



In digit IV the phalanges are like those of digit III, but they are all 

 free and are shorter, especially the proximal one ; the difference in size 



