ix.] PAL^ONTOLOG Y AND E VOL UTION. 183 



modification, or demonstrates such modification as has 

 occurred to have been very slight ; and, as to the nature 

 of that modification, it yields no evidence whatsoever 

 that the earlier members of any long-continued group 

 were more generalized in structure than the later ones/' 



I think that I cannot employ my last opportunity of 

 addressing you, officially, more properly I may say 

 more dutifully than in revising these old judgments 

 with such help as further knowledge and reflection, and 

 an extreme desire to get at the truth, may afford me. 



1. With respect to the first proposition, I may remark 

 that whatever may be the case among the physical 

 geologists, catastrophic palaeontologists are practically 

 extinct. It is now no part of recognized geological 

 doctrine that the species of one formation all died out 

 and were replaced by a brand-new set in the next forma- 

 tion. On the contrary, it is generally, if not universally, 

 agreed that the succession of life has been the result of 

 a slow and gradual replacement of sp.ecies by species ; 

 and that all appearances of abruptness of change are due 

 to breaks in the series of deposits, or other changes in 

 physical conditions. The continuity of living forms has 

 been unbroken from the earliest times to the present day. 



2, 3. The use of the word "homotaxis" instead of 

 "synchronism" has not, so far as I know, found much 

 favour in the eyes of geologists. I hope, therefore, that 

 it is a love for scientific caution, and not mere personal 

 affection for a bantling of my own, which leads me still 

 to think that the change of phrase is of importance, and 

 that the sooner it is made, the sooner shall we get rid of 

 a number of pitfalls which beset the reasoner upon the 

 facts and theories of geology. 



One of the latest pieces of foreign intelligence which 

 has reached us is the information that the Austrian 

 geologists have, at last, succumbed to the weighty 



