PRESIDENTIAL ADDRESS. 13 



The commingling in New Zealand strata of types which are 

 usually found to characterize separate formations has already 

 been referred to, but in this connection I also wish to mention 

 the reported discovery in those islands of Belemnites, Belem- 

 nitella, and Plesiosaurus in strata which have usually been 

 classed as Tertiary. There seems to be little reason to doubt 

 that this is an instance of a natural transition from the Creta- 

 ceous to the Tertiary, so gradually accomplished that it cannot 

 be said where the one ends and the other begins. 



A similar survival of Mesozoic types into an epoch, the strata 

 of which bear otherwise the fullest evidence of homotaxial rela- 

 tionship to the Eocene Tertiary, occurs in California. Here 

 there is found a species of Ammonite associated with numerous 

 genera which all paleontologists have agreed in regarding as 

 characteristic of the Tertiary. The series of strata which con- 

 tains this belated Ammonite is some ten thousand feet in thick- 

 ness, the lower part of which is homotaxially related to the 

 Cretaceous, and the upper part is similarly related to the Ter- 

 tiary, with the exception just mentioned. Still, this series of 

 strata has every appearance of having been produced by continu- 

 ous sedimentation, and of presenting an intercommingling of 

 Cretaceous and Tertiary types through the greater part, if not the 

 whole, vertical range of the series. 



In the cases which have just been mentioned, the continuation 

 of ancient types among those of later origin, or of more modern 

 characteristics, the comparison was made between the different 

 members of one and the same fauna for the different portions of 

 its existence ; but in the case now to be considered, the com- 

 parison is to be made between continental faunas and floras. 

 The case referred to is that of the Laramie Group. It will be 

 remembered that in my address before this society last vear I 

 made some extended remarks upon this group, showing that it 

 was deposited in a great inland sea of brackish and fresh waters. 

 Comparison, therefore, is to be made between the aqueous fauna 



