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PATAGONIAN EXPEDITIONS : PALAEONTOLOGY. 
concave and very shallow and is not grooved for the carina, but has 
merely a slight notch on the plantar border. Distally, the phalanx 
becomes somewhat narrower and thinner and the distal trochlea is nearly 
plane, with only a shallow emargination of the plantar border to indicate 
the usual division into two facets. The second phalanx is very small, 
especially in proximo-distal length, but is quite broad and thick in pro- 
portion to the length. The proximal articular surface is nearly plane, 
but the distal one is divided by a shallow, median groove into two parts 
and is reflected upon the dorsal side of the bone. The ungual is a small, 
asymmetrical hoof, not unlike that of the tapir ; the proximal trochlea is 
a very shallow concavity, divided by an obscurely marked, median ridge 
into two depressions. There is no subungual process. 
In the manus, the first phalanx of digit II is larger than that of the pes 
and broader relatively to its length ; the proximal trochlea is rather more 
concave, with plantar margin more distinctly notched for the metacarpal 
carina ; the distal trochlea is a little more convex and a very small area 
of it appears on the dorsal face. The second phalanx is very like that in 
the hind foot, except for its larger size and slightly more concave proximal 
articular surface. I have seen no example of the ungual phalanx. 
In the pes, the first phalanx of the third digit is very much larger than 
the corresponding one of the second digit and is proportionately broader 
and more depressed, and is also slightly asymmetrical. The very shallow 
concavity of the proximal end is not grooved for the carina, but the notch 
for it on the plantar margin is much more distinct and is continued dis- 
tally as a median depression between two rugose eminences on the 
plantar face. The distal trochlea is very nearly plane, but is a trifle 
more convex than in digit II. The second phalanx is likewise much 
larger than in digit II and proportionately broader and more depressed ; 
the distal articular surface is decidedly saddle-shaped and is reflected 
upon the dorsal side of the bone, but in a more symmetrical manner 
than in digit II. The ungual phalanx is large and quite symmetrical, 
and much depressed, with thin, rugose free border, but without any trace 
of the median cleft, which is replaced by a low ridge. In appearance, 
there is considerable resemblance to the median ungual of such Eocene 
Perissodactyla as Palceosyops. The trochlea has two continuous facets, 
of which that on the tibial side is distinctly the more concave. 
Of digit III in the manus, I have only the second phalanx. This is 
