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XI. Description of some Species of the extinct Genus Nesodon, with Remarks on the 
primary Group (Toxodontia) of Hoofed Quadrupeds, to which that Genus is 
referable. By Professor Owen, F.R.S. 8fc. 
Received Nov. 25, 1852, — Read January 13, 1853. 
The application of part of the Government Grant, allotted to procuring drawings 
of rare and nondescript fossil remains, has furnished the requisite illustrations of 
the following Memoir on some extinct Herbivorous animals, which indicate a 
primary group of the Ungulata, distinct from and probably equivalent to one of the 
great divisions called Proboscidia, Artiodactyla, and Perissodactylu. 
Genus Nesodon*, O. 
The genus so called, from most of the enamel-folds penetrating the crown of the 
molars being, when exposed by use, of an insular form, was founded by me in 1846'f', 
on portions of an upper and lower jaw, with teeth, transmitted by Captain Sulivan, 
R.N., from the S.W. coast of Patagonia. 
I have since received from the same zealous contributor of materials towards the 
advancement of our knowledge of the ancient zoology of South America, more exten- 
sive portions of both upper and lower jaws with teeth of the generic character of 
Nesodon, but belonging to a smaller species than that of which the first described 
specimens formed part; the second collection also contained detached teeth, indi- 
cating much larger species than either of the two above indicated. 
I propose to commence with the description of the remains of the smaller species, 
which from its size may be termed — 
Nesodo7i ovinus. Plates XV. and XVI. 
With the upper jaw of this species (figs. 1-5) are preserved the articular surface 
(figs. 1 and 3, g) for the right ramus of the lower jaw, the zygomatic arch (figs. 1 
and 2 , 26 and 27) and part of the nasal bones (figs. 1 and 2 , is). 
The total length of this portion of skull from the post-glenoid process (figs. 1 
and 3, pg) to the anterior incisor (fig. 1, di 1 ) is 6 inches 4 lines. The breadth of the 
* vijffos insula, odovs dens. 
t Abstracts of Papers in ' Reports of the British Association’ for 1846, vol. xvi. p. 66. 
+ The process, sometimes much developed, as in the Rhinoceros, e.g., is so called in my Catalogue of the 
Osteology in the Mus. Coll. Chir., which answers to the part described as the “ middle root of the zygoma ” 
in Anthropotomy (Bourgery, Traitd Complet de 1’ Anatomic de I’Homme, tom. R', plate 23, fig. 10, c.) 
MDCCCLIII. 2 Q 
