118 SKETCH OF THE HISTORY OF MAMMALIA. 



it may be that the toxodon, and even dinotherium, 

 form links between the lamantins and hippopotamus, 

 being within the pale of the group to which the former 

 belong. 



We may here observe, that the number of fossil ge- 

 nera included within the Pachydermata greatly exceeds 

 that of genera containing living species, of which latter 

 many, as Equus, Elephas, Rhinoceros, and Hippopo- 

 tamus, have fossil as well as living species : so that the 

 number of fossil or extinct species already ascertained of 

 the Pachydermatous order, taken collectively, is far 

 greater than the number of living species. In some, 

 perhaps many, instances the affinities of the fossil Pa- 

 chyderms are not understood, fragments of bones only 

 having been recovered : in some instances they cannot 

 be mistaken. 



We began our observation on the Pachydermata by 

 alluding to the unfilled intervals between the forms now 

 living on the surface of the earth, and a statement that 

 in fossil forms — some yet to be discovered, others to be 

 made out, and, as it were, re-constructed — would the 

 lost links in the chain be recovered ; and we again 

 express our opinion that ultimately the work will be, if 

 not ))erfectly, at least to a great extent, accomplished. 



That our ideas are not unreasonable we have from time 

 to time satisfactory proofs. Sir Thomas Mitchell has 

 recently transmitted from Australia some fossil bones 

 which incontestably prove the existence of at least one 

 gigantic Pachyderm, at some remote period, in that 

 region. These fossils consist of a portion of a molar 

 tooth, of the shaft of a thigh bone, with part of the 

 spine, of a scapula, and some smaller fragments of along 

 bone. They were found on the Darling Downs, those 

 extensive plains marked to the south-west of Moreton 

 Bay on most maps of Australia, at the source of the river 

 Darling, and upwards of 4000 feet above the level of 

 the sea. Sir Thomas Mitchell, in his letter to Professor 

 Owen, to whom the relics were forwarded, states that 

 these huge bones are found in some abundance. It 

 would appear from Professor Owen's examination, that 



