ON BIOLOGY. 25 



discovered from time to time in the various geologic 

 horizons making up the crust of the earth. This is 

 especially fortunate inasmuch as that aspect of the sub- 

 ject has thas been brought before you by one of the 

 most able of all living polaeobotanists, as it does at the 

 same time relieve me of the necessity of passing into 

 similar fields for facts for my next lecture, e'en had I 

 the ability to present the matter with that lucidity and 

 breadth that I have no manner of doubt was done for you 

 by Prof. Ward. 



Finally, to those who may be especially interested in 

 the present course of lectures and at the same time con- 

 sider themselves to be but tyros in the science of biology, 

 and desire by their reading to look into the subject of 

 each succeeding lecture, prior to my delivering it, I 

 would say that in considering the relation of biology to 

 geology we will also take into consderation the question 

 of the geographical distribution of many of the groups 

 of the world's existing vertebrata, as that is a matter of 

 prime importance to be dealt with, to the end that we 

 may attain to an understanding of the subject in chief. 



