ON A PIECE OF CHALK 69 



which existed at that remote epoch. The Globige- 

 rina of the present day, for example, is not different 

 specifically from that of the chalk ; and the same may 

 be said of many other Foraminifera. I think it prob- 

 able that critical and unprejudiced examination will 

 show that more than one species of much higher ani- 

 mals have had a similar longevity; but the only ex- 

 ample, which I can at present give confidently is the 

 snake's-head lamp-shell (Terebratulina caput serpentis) , 

 which lives in our English seas and abounded (as Tere- 

 bratulina striata of authors) in the chalk. 



The longest line of human ancestry must hide its 

 diminished head before the pedigree of this insignifi- 

 cant shell-fish. We Englishmen are proud to have an 

 ancestor who was present at the Battle of Hastings. 

 The ancestors of Terebratulina caput serpentis may 

 have been present at a battle of Ichthyosauria in that 

 part of the sea which, when the chalk was forming, 

 flowed over the site of Hastings. While all around has 

 changed, this Terebratulina has peacefully propagated 

 its species from generation to generation, and stands 

 to this day, as a living testimony to the continuity of 

 the present with the past history of the globe. 



Up to this moment I have stated, so far as I know, 

 nothing but well-authenticated facts, and the imme- 

 diate conclusions which they force upon the mind. 



But the mind is so constituted that it does not wil- 

 lingly rest in facts and immediate causes, but seeks 

 always after a knowledge of the remoter links in the 

 chain of causation. 



Taking the many changes of any given spot of the 

 earth's surface, from sea to land and from land to sea, 

 as an established fact, we cannot refrain from asking 



