198 PROCEEDINGS OF THE ACADEMY OF [1883, 



where there may have been a reversal of the strata themselves, 

 was there evidence of a reversed i)osition. Corresponding strata, 

 as indicated by the contained fossils, had tlierefore been supposed 

 to belong to the same age, althougli occurring in widely separated 

 regions. This view, for a long time maintained undisturbed by 

 the earlier geologists %nd palaeontologists, had, however, been 

 dissented from by Edward Forbes, Huxley, and other advocates 

 of the doctrine of faunal dispersion from localized areas or centres 

 of distribution (opponents of independent creation), on the obvious 

 ground, that faunas starting from a given point of origination 

 could only spread by migration, and that such migration must 

 consume time, proportional to the distance traveled and the ph3's- 

 ical and phj'siographical facilities afforded for traveling. Hence 

 it was argued that widely separated formations showing an 

 equivalent faunal facies, as, for example, the Silurian of America 

 and the Silurian of Europe or eastern Asia, or the Cretaceous of 

 Europe and South America, could not be of identical age, and, 

 with a fair show of probability, not even appi'oxiraately so. In 

 support of this position it has been urged that during the present 

 age of the world the faunas of the several continents are widely 

 distinct, and could, under geological conditions, be considered as 

 indicating different zoological (geological) eras. In conformity 

 with this view, Professor Huxley had proposed (Anniversary 

 Address, Geol. Soc, 1862. Q. J. Geol. Soc, xviii, p. xlvi) the term 

 " homotaxis," indicating similarity of arrangement, in place of 

 sjaichrony, to describe the relations of distant areas of the same 

 formation. 



Pushing his conclusion to what appeared to be its furthest legit- 

 imate point. Professor Huxley deduced therefrom two important 

 considerations : 



I. That formations exhibiting the same faunal facies may belong 

 to two or more very distinct periods of the geological scale as 

 now recognized ;and conversely, formations whose faunal elements 

 are quite distinct, may be absolutely contemporaneous ; e. g. : 

 " For anything that geology or palaeontology is able to show to 

 the contrary, a Devonian fauna and flora in the British Islands 

 may have been contemporaneous with Silurian life in North Amer- 

 ica, and with a Carboniferous fauna and flora in Africa " (loc. cit.). 



II. That, granting this disparity of age between closely related 

 faunas, all evidence as to the uniformity of physical conditions 

 over the surface of the earth during the same geological period 

 {i. e., the periods of the geological scale), as would appear to be 

 indicated by the similarity of the fossil remains belonging to that 

 period, falls to the ground. " Geogi'aphical provinces and zones 

 may have been as distinctl}' marked in the Palseozoic epoch as at 

 present, and those seemingly sudden appearances of new genera 

 and species, which we ascribe to new creation, ma}' be simple 

 results of migration." 



These views, enunciated b}- Prof. Huxley, were still largely 



