GEOLOGICAL EXTERMINATIONS. 



173 



Discussion. 



Dr. Henry Woodward, F.K.S. — Your Secretary has been so 

 kind as to send me an invitation to come to-day. 



I am sorry that the author took as his copy and authority the 

 text-book of Dana, because geological science is one that is always 

 progressing, and you have only to notice the fact that although 

 this work of Dana's has been a most valued text-book of geology 

 in America, and has been largely used on this side also, that it 

 began its first edition about 1859, the second was published in 

 187-t, and the third in 1879. Wei] now, between 1879 and the 

 present time a great advance in geology has occurred, and I think 

 that it is hardly possible that any geologist or palaeontologist can 

 accept the idea of the entire extermination of life in geological 

 time in the sense that Professor Dana and the author express it. 

 Whether we accept and endorse the views of Darwinian evolution, 

 or we retain the old conviction with regard to the creation of all 

 the varied forms of life, we are convinced of one thing, that from 

 the time that life first appeared upon the globe, it has never been 

 entirely exterminated. That is a fundamental principle which I 

 think one might accept without any prejudice or reserve, that life 

 having once commenced upon the earth, it has never disappeared 

 from it. 



Then with regard to the appearance of that life. All through 

 the geological periods we have a [succession of forms appearing, 

 but of the many groups that have vivilied the surface of the earth, 

 and the waters of the sea, very few indeed have been entirely 

 exterminated.* A few groups have become extinct in the course 

 of long periods of time ; such forms as the Trilobites have disappeared. 

 Hugh Miller's great " cherubims " (Pterygoti), found in the Upper 

 Silurian and Devonian rocks, have entirely ceased to live. But the 

 great class of Crustacea to which they belong remains just the 

 same and has gone on through all periods of time, different species 

 having been evolved in a regular orderly sequence up to the present 

 day. I do not think, either, that one can accept the idea of any 



* Of the invertebrata I find eighteen groups which are persistent ; 

 three are extinct ; and live groups are of comparatively modern appear- 

 ance in time. 



