284 THE ZOOLOGIST. 



teacece), similar to those which at the present day flourish in 

 Australia.* Many shells, "though they belong to extinct ani- 

 mals, resemble those which are confined at the present day to 

 warmer seas," including a fossil Nautilus, a genus which is 

 represented by several species in the London clay.t Even our 

 roads are sometimes paved with the remains of " extinct mon- 

 sters." I remember some years ago, near Street, a village in 

 Somersetshire, watching some stone-breakers at their melan- 

 choly occupation, and, as they broke up the Blue Lias with 

 their hammers, the teeth of some old Saurians were exposed. 

 Our coal-scuttles contain the remains of extinct plants, and the 

 hideous pall of black smoke vomited from the industrial centres 

 of which our pseudo-civilization is so proud proclaims the com- 

 bustion of a flora no longer existant. The fossil resin from 

 extinct Couiferce supplies the amber mouth-piece of the pipe we 

 smoke ; we ourselves are living species surrounded by and making 

 use of the remains of others long extinct. 



The effects of glacial epochs are perhaps now beginning to be 

 understood as of a sometimes more exterminative and of a less 

 distributive character than was formerly the general opinion. It 

 was quite simple to invoke a glacial epoch as a giant spectre 

 which first drove living nature south, and then attracted its 

 return by the genial influences which attended glacial retreat. 

 Eetreating forms of life through glacial influences, and their 

 subsequent return when such phenomena were alleviated, was a 

 common argument in all distributive essays ; it is now becoming 

 an axiom in the study of evolution that these icy visitations often 

 caused wholesale extermination. Many animals and plants 

 stayed to die before they endeavoured to flee and live — at least, 

 very often so. The gradually approaching conditions of a severe 

 environment insidiously weakened plant and animal life ; 

 lethargy anticipated death, sudden changes of temperature 

 effected wholesale slaughter, and, as in our own casual and 

 unusually severe winters, there are swift swings of the pendulum 

 which determine the effacement of much that would have sur- 

 vived had the stress been gradual. In these glacial spasms the 

 intensified effects took place of what we can only realize in the 



* Huxley, ' Physiography,' p. 229. 

 f Id., loc. cit., pp. 28S-9. 



