842 PALAEONTOLOGY AND EVOLUTION xi 



existence of such forms is recorded, is small. 

 When compared with the lapse of time since 

 the first appearance of these forms, the amount 

 of change is wonderfully small. Moreover, in 

 each great group of the animal and vegetable 

 kingdoms, there are certain forms which I termed 

 Persistent Types, which have remained, with 

 but very little apparent change, from their first 

 appearance to the present time. 



6. In answer to the question " What, then, does 

 an impartial survey of the positively ascertained 

 truths of palaeontology testify in relation to the 

 common doctrines of progressive modification, 

 which suppose that modification to have 

 taken place by a necessary progress from more 

 to less embryonic forms, from more to less general- 

 ised types, within the limits of the period 

 represented by the fossiliferous rocks ? " I reply, 

 " It negatives these doctrines ; for it either 

 show us no evidence of such 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 what- 

 soever that the earlier members of any long-con- 

 tinued group were more generalised in structure 

 than the later ones." 



I think that I cannot employ my last opportu- 

 nity of addressing you, officially, more properly — > 

 I may say more dutifully — than in revising these 

 old judgments with such help as further know- 



