VIEWS OF HUXLEY AND GEIKIE 139 



Huxley,* in his anniversary address before the Geological Society of 

 London in 1862, said : 



" Paleontology has established two laws of inestimable importance: The first, that 

 one and the same area of the earth's surface has been successively occupied by very 

 different kinds of living beings; the second, that the order of succession estab- 

 lished in one locality holds good, approximately, in all. . . . As a consequence of 

 the second law, it follows that a peculiar relation frequently subsists between series 

 of strata, containing organic remains, in different localities. The series resemble 

 one another, not only in virtue of a general resemblance of the organic remains in 

 the two, but also in virtue of a resemblance in the order and character of the serial 

 succession in each. There is a resemblance of arrangement ; so that the separate 

 terms of each series, as well as the whole series, exhibit a correspondence. Succes- 

 sion implies time ; the lower members of a series of sedimentary rocks are certainly 

 older than the upper ; and when the notion of age was once introduced as the 

 equivalent of succession, it was no wonder that correspondence in succession came 

 to be looked upon as correspondence in age, or 'contemporaneity.' And, indeed, 

 so long as relative age only is spoken of, correspondence in succession is correspond- 

 ence in age ; it is relative contemporaneity. Bat it would have been better for 

 geology if so loose and ambiguous a word as ' contemporaneous ' had been excluded 

 from her terminology, and if, in its stead, some term expressing similarity of serial 

 relation, and excluding the notion of time altogether, had been employed to denote 

 correspondence in position in two or more series of strata. In anatomy, where such 

 correspondence of position has constantly to be spoken of, it is denoted by the 

 word ■ homology,' and its derivatives ; and for geology (which, after all, is only the 

 anatomy and physiology of the earth), it might be well to invent some single word, 

 such as ' homotaxis ' (similarity of order), in order to express an essentially similar 

 idea." 



Huxley further called attention to the fact that it is generally admitted 

 by all the best authorities 



" that neither similarity of mineral composition, nor of physical character, nor 

 even direct continuity of stratum, are absolute proofs of the synchronism of even 

 approximated sedimentary strata; while for distant deposits, there seems to be no 

 kind of physical evidence attainable of a nature competent to decide whether such 

 deposits were formed simultaneously, or whether they possess any given difference 

 of antiquity. f 



" Edward Forbes was in the habit of insisting that the similarity of the organic 

 contents of distant formations was prima facie evidence, not of their similarity, but 

 of their difference of age. "J 



His conclusion was that 



"There seems, then, no escape from the admission that neither physical geol- 

 ogy nor paleontology possesses any method by which the absolute synchronism of 

 two strata can be demonstrated. . . . For areas of moderate extent it is 



*Q. G. G. S., London, vol. xviii, p. xli. 

 fLoc. cit., p. xliv. 

 X Loc. cit., p. xlv. 



