136 THE DESEADO FORMATION OF PATAGONIA 
inclosed basin becomes a large pit. Between the posterior 
Jobe and the flaring cingulum on the posterior margin, 
there is also a small posterior bay, which, in an old tooth, 
will also appear as a pit, but being shallow, it does not 
last long. 
The lower molars, as figured by Ameghino, are of the 
same type as those of the toxodonts, consisting of two cres- 
cents with the pillar in the middle of the posterior cres- 
cent, but the crescents and pillar are very plump; so that 
with wear they form broad grinding surfaces; and the 
bays, instead of becoming pits, first appear as notches, 
then disappear entirely. Each premolar and molar has a 
cingulum on the internal and external sides. 
Fig. 93. Premolar 4 to molar 3—1/2 natural size, after Ameghino. 
MEASUREMENTS, SPECIMEN 3179 
Upper dentition, molar 1, length 46 mm., width 50 mm. 
Upper dentition, molar 2, length 51 mm., width 55 mm. 
Upper dentition, molar 3, length 50 mm., width 51 mm, 
Lower dentition, from Ameghino’s measurements 
Lower dentition, premolar 4, length 28 mm., width 23 mm. 
Lower dentition, molar 1, length 34 mm., width 24 mm. 
Lower dentition, molar 2, length 46 mm., width 24 mm. 
Lower dentition, molar 3, length 76 mm., width 23 mm. 
Only the distal end of the scapula has been found; and 
this shows a shallow glenoid cavity, which is much longer 
in the antero-posterior direction, than in the transverse. 
The spine rises close above the rim of the glenoid, and is 
unusually heavy. 
The lower half of the humerus is present, and character- 
ized by very wide epicondyles, a shallow supratrochlear 
fossa, a moderately deep anconeal fossa, no foramen, and 
a wide shallow trochlea. The ulna, according to Gaudry, 
is a long, heavy, nearly straight bone, with a shallow sig- 
