182 ON A NEWLY DISCOVERED EXTINCT MAMMAL FROM PATAGONIA. 
rhinocerotic than tapiroid in character. These evidently belong to some hitherto 
unknown form ; if Homalodontotherium, they are of smaller dimensions than would be 
inferred from the teeth, unless the animal had a disproportionately large and heavy head. 
3. A fragment, apparently the inner half of the lower articular extremity of a tibia of 
an animal of much larger proportions, nearly equalling the Indian Rhinoceros. If I am 
right in its determination it is rather anomalous in its characters, somewhat resembling 
in general shape the corresponding part of the Tapir, but having a deep roughened 
depression notching the inner margin of the smooth articular surface, similar to that 
seen in the Hippopotamus alone among recent Ungulates. 
4. A fragment of the shaft of a long bone, 10 inches in length, apparently the hinder 
border of an ulna of an animal as large as that to which the last-mentioned piece belonged. 
These specimens will be deposited with the teeth in the British Museum, and will 
become of greater interest when compared with others that we may hope to obtain by 
future explorations in the same locality. It is possible that they may belong to one or 
other of the species of Hesodon , of which one, A. magnus , only known from a fragment 
of a molar tooth, equals the largest Rhinoceros in size*. 
Description op the Plate. 
PLATE XVI. 
Fig. 1. Side view of the upper teeth of Homalodontotherium Cunninghami. 
Fig. 2. Side view of the lower teeth. 
Fig. 3. Grinding-surface of the left lower teeth. 
Fig. 4. Grinding-surface of the left upper teeth. 
All of the natural size. 
ae c. Anterior external cusp. 
a i c. Anterior internal cusp of the molar teeth ; the corresponding parts 
of the incisors are marked with the same letters. 
pec. Posterior external cusp. 
p i c. Posterior internal cusp. 
ar. Anterior transverse ridge. 
p r. Posterior transverse ridge. 
as. Anterior sinus. 
ms. Median sinus. 
p s. Posterior sinus. 
a t. Anterior talon or accessory cusp. 
p t. Posterior talon or accessory cusp. 
1. External wall or lamina. 
* See “ Description of some species of the extinct genus Nesodon &c.” by Professor Owen, F.R.S., Phil. Trans, 
vol. cxliii. (1853) p. 291. 
