ANNIVERSAEY ADBEESS OF THE PEESIDEXT. Ixxiii 



to find it brouglit before us in recent geological times *. Apart 

 from such, an exceptional case, I consider that, if all disturbing 

 causes be properly taken into account, the percentage test is a 

 good and useful guide for the chronological arrangement of the newer 

 strata ; nor, notwithstanding its exceptional character, do I con- 

 sider that a case like the one just referred to need perplex the 

 geologist, who would seek elsewhere, in superposition or in some 

 points of physical structure, for evidence as to place. Palaeonto- 

 logy is an excellent counsellor, but it should always be kept sub- 

 ordinate to stratigraphical geology. It indicates what may be the 

 case, but it does not teU us what must be the case. The one 

 has rigid, the other flexible lines ; and these lines are rarely pa- 

 rallel. The geologist should first determine rigorously the order of 

 superposition, before he speculates on the distribution of the fauna. 

 Btedfast in that mode, there need be no cause for error, however 

 exceptional and varying the fauna may be. It is his business to 

 determine the fact, and then, with the aid of the palaeontologist, 

 to discover the cause and amount of variation, and to detect the 

 principle on which the distribution of life in the period under 

 investigation has been regulated. Palaeontology must be our guide, 

 but not our master. It is this which gives life and interest to so 

 many of the higher problems of palseontological geology. 



In one point of view, the geologist has the advantage over the 

 naturalist. The latter examines the coasts and dredges in the 

 ocean, but he can only skim the surface, whereas the former has 

 the old sea-beds opened out to him. He can see, at any given 

 time, what has been below the surface. The dredge may pene- 

 trate a few inches ; but the old shoals and sheU-banks of the 

 .Coralline Crag sea, for example, can be opened out to the depth of 

 10, 20, 30 feet or more, exposing the range of life both in time 

 and in horizontal distribution at any given epoch. What may be 

 under the surface' of the Atlantic mud we know not. Is there a 

 succession of strata extending down to the equivalents in time of 

 our chalk strata ? or would the equivalent of the latter prove to 

 be merely one part of a series, the other end of which would 

 convey us back to Oolitic, Jurassic, Triassic, or even to Carboni- 

 ferous times ? Many of the forms of life indicate a sequence in 

 this great chain. Some of our present marine Foraminifera go back 



* The absence of any known deposits in our Tertiary series of a character 

 like the present deep Atlantic mud is another proof that none of that part of the 

 old ocean-bed has been raised since the Chalk period. 



VOL. XXVII. / 



