MARSUPIALIA. 



Diprotodon (fig. 156). Represented by a single species, Diprotodon 

 australis, as large as a rhinoceros, being indeed the largest known marsupial. 

 The skull measures nearly a metre in length, and the greater part of the 

 >kcloton of the trunk and limbs is known. The dental formula is 



- , thus similar to that of the kangaroos, but no 

 i. 1, c. 0, pm. 1, m. 4 ' 



successional teeth have been observed. The foremost pair of upper 

 incisors is chisel-shaped, much larger than the other two pairs, and 

 growing from persistent pulps. The lower incisors resemble and oppose 

 the front upper pair, also growing from persistent pulps. The premolar 

 in both jaws is insignificant and early shed. All the molars are rooted, 

 and each crown consists of two transverse ridges, without any small 

 longitudinal ridge to connect them. There is a large downwardly directed 



FIG. 156. 



Diprotodon australis; skull and mandible, left lateral aspect, one-tenth nat. 

 size. Pleistocene ; Queensland. (After Owen.) 



process from the zygomatic arch. 9 The limbs are of nearly equal length 

 and adapted for walking.! The humerus is remarkable as wanting an 

 entepicondylar foramen ; the radius and ulna move freely upon each 

 other, and the latter bone has scarcely any olecranon process. The hind 

 foot is proved to have had five very small and short toes, each with a little 

 hoof ; the fore foot appears to have been similar. Diprotodon occurs only 

 in the supposed Pleistocene cave-deposits, fluviatile and lacustrine forma- 

 tions of New South Wales, South Australia, and Queensland. 



Nototherium, found with Diprotodon, is a smaller animal than the 

 latter, with shorter and broader skull, but a similar dental formula. The 

 snout is somewhat constricted in front of the orbit, and the nasal bones a 



