AUSTRALIAN MAMMALS 305 



remarkable modifications of its limbs. The hind pair were 

 much shortened and strengthened, compared with those of the 

 kangaroo ; the fore pair were lengthened as well as strength- 

 ened ; yet, as in the case of the Megatherium, the ulna and 

 radius were maintained free, and so articulated as to give the 

 fore paw the rotatory actions. These in Diprotodon, would be 

 needed, as in the herbivorous kangaroo, by the economy of 

 the marsupial pouch. The dental formula of Diprotodon 

 was i j^j, c -Q,p iEi>^fEi=28,* and, as in Macropus major, 

 the first of the grinding series (_p) was soon shed; but the 

 other four two-ridged teeth were longer retained, and the 

 front upper incisor (i, i) was very large and scalpriform, as in 

 the wombat. The zygomatic arch sent down a process for 

 augmenting the origin of the masseter muscle, as in the 

 kangaroo. The foregoing skull, with parts of the skeleton, 

 of the Diprotodon Australis, were discovered in a lacustrine 

 deposit, probably pleistocene, intersected by creeks, in the 

 plains of Darling Downs, Australia. 



The same formation has yielded evidence of a somewhat 

 smaller extinct herbivorous genus (Noto- 

 theriumY combining, with essential affi- 

 nities to Meter opus, some of the characters 

 of the Koala (Phascolarctusy-\ The 

 writer has recently communicated de- 

 scriptions and figures of the entire skull . , lg ' l 



t Grinding surface of molar 



of the ISototkerium Mitchelli to the Geo- f Phascolomys gigas 

 logical Society of London.^ The genus (nat. size), Pleistocene, 



Pheiscolomys was at the same period 

 represented by a wombat (P. gigas) of the magnitude of a 

 tapir, one of the grinding teeth of which is represented, of the 

 natural size, in fig. 140. 



* See that of Macropus, explained in Ency. Brit., article Odontology, p. 449. 

 f "Report on the extinct Mammals of Australia," Trans, of Brit. Assoc, 

 1844. 



% Quarterly Journal of the Geol. Soc, pt. iv., 1858. 



