326 The Bate of Geological Change. [July, 



These quotations show that so keen an observer and so 

 thoughtful a philosopher as Professor Phillips had not allowed this 

 subject to escape him ; but I am not aware that any other geologist 

 has discussed it from precisely the same point of view. The figures 

 given by Professor Phillips show that the rate of geological change, 

 with regard to the relation "between the deposition of strata and the 

 changes in faunse, was neither uniform throughout all geological 

 times, as the Uniformitarians would have it, nor more intense in 

 the earlier periods, as the Catastrophists contend. On the contrary, 

 these figures prove, to the extent which they go, that the rate of 

 change was marvellously more rapid in the more recent periods, 

 and that the increase in rapidity was rapidly progressive, from the 

 earliest to the latest times. There are four times as many species* 

 belonging to the eight classes which are persistent through- all 

 geological periods, per 1000 feet, in the Mesozoic strata than in the 

 Palaeozoic, and there are three times the number t of such species 

 per 1000 feet in the Cainozoic strata that there are in the Mesozoic. 



In the same year (1860), Professor Phillips, as President of the 

 Geological Society, delivered the Anniversary Address to the Fellows, 

 and again adverted to this subject, and the following quotation 

 gives his conclusions, as delivered before one of the most critical 

 geological audiences in Europe : — 



" In the earlier periods of the world's history, the changes of 

 life in the sea were accomplished at a rate much less rapid than 

 that which prevailed in later times,\ which agrees with the acknow- 

 ledged very wide distribution of Palaeozoic forms in geographical 

 space. Admitting the changes of life on the whole to be equal 

 from the Palaeozoic to the Mesozoic, and from these to the Cainozoic 

 periods, we find the rate of progressive change § T Vth for Palaeozoic, 

 Tsth for Mesozoic, and ird for Cainozoic time, — a conclusion of great 

 importance, and probably indicative of the greater influence and 



or slow, in proportion as changes in climate and physical geography have been 

 frequent or seldom. In the Palaeozoic periods we have reason to believe that 

 changes in physical geography were rare, while the climate aud the nature of the 

 earth's surface were very slightly diversified. In the Tertiary epoch, on the con- 

 trary, climate and physical conditions have been very diverse, and have frequently 

 varied ; and these variations have been accompanied by proportionate changes of 

 species. If periods of small duration had been compared by Professor Phillips, it 

 is quite certain that the chances of error would have been very great ; but by put- 

 ting in contrast only the three great epochs into which Geological Time has been 

 divided, I believe that those chances of error have been reduced to a minimum, 

 according to the well-known law of averages. — H. M. J, With all defereuce to 

 so eminent a geologist as Professor Phillips, and to the author of this essay, it 

 appears to me that such a table is an unsafe guide in the present state of the 

 palseontological record. Here, for example, the fishes — the most important group 

 of all, biologically— are entirely omitted. — Editor. 



* According to my calculation, twice as many. f I make it six times. 



X The italics are mine. — H. M. J. 



§ Taking the unit of thickness such that it shall be r^th of the ascertained 

 strata in which life-traces occur. 



