xliv PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



gists that I need not argue the question, especially with those who 

 understand the details of the intermediate Devonian fauna. 



2nd. Some one geologically quite as heterodox, in the modern 

 reading of the term, may declare that when the Silurian life was 

 driven out of this area, it is possible that it may have continued 

 to live elsewhere as late as our Carboniferous epoch ; but when the 

 latter began, it so happened that our area was repeopled, not from 

 a Silurian district, but from some other region, where life of a Car- 

 boniferous type was rife ; and this kind of argument has frequently 

 been enforced by the statement that, if the modern Australian life 

 were fossilized, we might mistake it for that of part of the Oolitic 

 epoch *. 



Such a statement is most difficult to deal with in the present 

 state of the science ; for the arguments against it can scarcely be 

 reduced to demonstration, and instinctive feeling must not be mis- 

 taken for truth. If it be true indeed that, " for anything geology or 

 palaeontology are able to show to the contrary, a Devonian fauna 

 and flora in the British Islands may have been contemporaneous 

 with Silurian life in North America, and a Carboniferous fauna and 

 flora in Africa," there will, in the opinion of some, be a risk that the 

 very foundations of geological orthodoxy are so sapped and shaken 

 that the whole column must tumble about our ears, if that column 

 be based upon a doctrine of palaeontological succession, which, as now 

 understood, has thus become " a mockery, a delusion, and a snare." 

 I shall return to the question towards the close of this Address, merely 

 at present remarking that the well-known Australian case vanishes, 

 when examined, into the region of loose generalization ; for geology 

 and palaeontology deal chiefly with sea-bottoms, and if we compare 

 that of the Australian sea with those of Oolitic age,' we shall find 

 that, though the former holds Trigonia, Lingula, Terebratula, and 

 Cestraciont Sharks, yet these form but a very small percentage of a 

 vast fauna, easily distinguishable as of late Tertiary, that is to say, 

 of modern type. If fossilized, in fact, there would be no more 

 danger of our confounding an existing Australian and an Oolitic 

 period because of the Trigonia, Terebratula, <fcc. of the former, than 

 there is of confounding an Oolite and a Carboniferous formation 

 because of the Terebratula^, the Rhynchonellw, the Spiriferce, and the 

 Nautili in both. 



3rd. It may be that mere time had effected the change in species 

 and genera in other areas, during the period in which the Old Red 

 Sandstone was deposited under conditions locally unfavourable to 

 life, such duration of time being much enhanced, if it can be proved 

 that the Old Red Sandstone consists of two or more unconformable 

 members. 



That the Old Red Sandstone of Shropshire and Wales was not 

 deposited in an area of general and unbroken depression is almost, 

 if not quite, demonstrable ; and if so, in this case change of life is 



* I use this argument here at random. It is equally applicable to every 

 other case of geological superposition and succession of life, but it is needless to 

 repeat it in each instance. 



