200 
PATAGONIAN EXPEDITIONS I PALAEONTOLOGY. 
Measurements. 
P a , length .... 
. .022 
M- 2 -, length 
•055 
“ width .... 
. .022 
“ width ...... 
•045 
P-, length .... 
. .024 
Skull, length occip. crest to tip of nas. . 
•379 
“ width .... 
. .024 
Cranium, length cond. to orbit. . 
•235 
PL length .... 
. .024 
Occiput, height 
.179 
“ width .... 
. .026 
width at base .... 
•195 
Upper molar series, length . 
. .117 
Sagittal crest, length .... 
.106 
M— , length .... 
• -035 
Zygomatic arch, length 
.156 
“ width .... 
• -033 
Cranium, width at constriction . 
.050 
M-, width .... 
. .042 
Nasals, length. ..... 
.198 
Localities. — The type specimen (No. 16,012) was found by Mr. Hatcher 
at Lake Pueyrredon. The teeth show that the animal was past maturity. 
ADINOTHERIUM Ameghino. 
(Plates XII, XVII, XVIII, XX, XXI, XXVI, XXVII.) 
Nesodon Owen (in part); Phil. Trans., 1853, p. 291. 
Adinotherium Amegh. (in part); Enum. sistemat., etc., 1887, P- I 7 - 
Acrotherium Amegh. (in part) ; Ibid. 
Nesodon Lydekker (in part); Anales del Mus. de La Plata, T. II, 1893, 
p. 25. 
Noaditherium Amegh.; Anales del Mus. Nac. de Buenos Aires, T. XVI, 
1907, p. 84. 
Most writers on the subject have united this genus with Nesodon , but 
I am inclined to follow Ameghino in regarding it as distinct. The most 
characteristic features of difference maybe enumerated as follows: (1) 
The species of Adinotherium are all much smaller animals than those of 
Nesodon , with no transitions. In itself, this difference is not of generic 
value, but it is constant and not without significance. (2) The upper 
premolars are of somewhat simpler pattern, a distinction which can be 
observed only in nearly or quite unworn teeth. (3) The anterior lobe of 
the lower molars is relatively broader — the posterior lobe narrower. (4) 
The rostrum, including the anterior part of the mandible, is much more 
decidedly broadened, suggesting the form of this region in Toxodon. (5) 
In some species, at least, there is on each frontal a convex rugosity, which 
apparently indicates the presence of a small dermal horn. In addition, 
there are several constant and characteristic differences in the vertebrae 
