produced by great Geographical Changes, 393 



have reduced the once great families to which these animals be- 

 longed to a few and scattered members*. 



It has been demonstrated by Professor Owen, that in the 

 earlier types of Vertebrata there were blended in one animal cha- 

 racters which have now become the peculiarities of suborders ; 

 and all the observations of naturalists conspire to show that as 

 we recede iu order of time, the confluence of types tends to a 

 junction of branches with stems, and these again at remoter 

 points with trunks conducting towards a root common to the 

 animal and vegetable kingdoms. If, therefore, it can be shown 

 with any degree of probability that there exist remnants of an 

 earlier state of being, preserved in a state of complete isolation, 

 which belong exclusively to one or more of the simpler forms, as 

 is the case with the implacental mammalia of Australia, another 

 link is added to the chain of evidence that all forms of life have 

 originated, by a natural course of reproduction and slow varia- 

 tion, from one common root. 



I would also lastly add that the unequal rate of change in 

 some families of mammalia compared with others, and particu- 

 larly the remarkable constancy of character exhibited by the 

 Macacus since the eocene period, while entire suborders of Un- 

 gulata, which were coexistent with that genus, have disappeared, 

 may serve to elucidate the antiquity of man, and seems to me to 

 lead us to the presumption of a far greater antiquity for our race 

 than has hitherto been accorded to it, reaching perhaps far back 

 into the tertiary period. 



Whether the inferences I have ventured to draw as to the 

 alignement of the lands during the three periods into which geo- 

 logical formations are divided, and the preservation of portions of 

 that land and of its inhabitants in an isolated condition, be or 

 be not well founded, it will be my endeavour to collect all new 

 facts bearing on the subject which the labours of geologists are 

 constantly accumulating, and to collate them with impartialitj', 

 whether they support or militate against these inferences, and I 

 hope at some future day to embody them in another paper. 



* This process of the isolation and subsequent incorporation of detached 

 lands taking place at very remote dates may perhaps afford an explanation 

 of the much debated and apparently anomalous case of the anthraxiferous 

 beds of the Alps, where, alternating with beds containing remains of plants 

 all belonging to palaeozoic genera, and in many cases to well-known car- 

 boniferous species, occur beds with true liassic forms of mollusca. See S. 

 Gras, Bull. vol. xii. p. 273. 



