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PATAGONIAN EXPEDITIONS : PALAEONTOLOGY. 
laries have almost the same proportions as in the latter, while the lachry- 
mals are distinctly smaller, though of similar shape, and have quite 
prominent spines. Owing to the posterior height of the zygomatic 
arches, where they rise almost to the level of the sagittal crest, the 
descent of the arches forward is steeper than in Nesodon and the jugal 
has a more distinct postorbital process or angulation. 
The hard palate differs in some particulars from that of Nesodon , though 
the difference can be fully appreciated only when the comparison is made 
between skulls which are quite free from lateral crushing. In such skulls, 
the most obvious difference in the palate is its much more triangular form 
in Adinotherium, being relatively broader behind and narrowing forward 
more strongly to the line between the foremost premolars, thence widen- 
ing again to the muzzle, which, as already frequently mentioned, is 
decidedly broader than in Nesodon. Individually, the various elements 
of the bony palate differ very little from those of the last named genus, 
save as such difference is conditioned by the general form of the whole. 
The two rows of grinding teeth converge forward much more strongly 
than in Nesodon. The posterior nares, palatines and pterygoids are so 
nearly as in the latter that no particular description of these parts is 
required. 
The mandible differs in some respects from that of Nesodon. As in 
the latter, the two halves are, in the adult, indistinguishably fused into a 
single bone and form a long symphysis which is deeply channelled on 
the dorsal side. One of the most obvious differences from Nesodon is in 
the shape of the symphysial region, which, when viewed from above, is 
seen to be more distinctly constricted at the line of p2 and to widen 
more from this point to the incisive alveoli, in correlation with the similar 
broadening of the upper jaw. The ventral profile of the chin also differs 
in being somewhat less steeply inclined and more procumbent. The 
horizontal ramus has a relatively greater dorso-ventral depth than in 
Nesodon , though the difference is not a striking one, while the propor- 
tions of length and thickness are nearly identical in both genera. In 
Adinotherium, however, the ventral border is more strongly and simply 
convex, less sinuous, and the ascending ramus has a considerably greater 
antero-posterior breadth in proportion to the length of the tooth-row. 
The sigmoid notch is shallower than in Nesodon and the coronoid is 
reduced, not rising above the level of the condyle, which is much as in 
