CHAP, ii.] GENERAL CONCLUSIONS. 35 



possess characters bringing them into relation with one 

 or other of the families of hoofed quadrupeds living in 

 the Eocene period (see Fig. 5). 1 



The Climate of Britain Tropical. 



The climate of Britain is proved to have been tropical 

 from the time of the London Clay down to the close of 

 the Eocene period by the concurrent testimony of the 

 flora and of the fauna. Just as a high temperature is 

 necessary for the well-being of the feather-palms (see 

 Fig. 4) and large fan-palms, so is it necessary for the 

 full development of the larger forms of reptilian life, 

 such as the alligator, crocodile, and gavial. Among 

 living mammals, the tapir, the inhabitant of the warmer 

 regions of Asia and America, is the closest represent- 

 ative of a large section of the Eocene mammalia, and 

 the lemurs of the present day are only found in' hot 

 climates. The nautilus, larger volutes, cowries, and 

 other shells, so common in the Eocene strata, are now 

 only to be met with in the tropical and sub-tropical 

 seas. 2 Mr. Starkie Gardner estimates the mean annual 

 temperature of Britain in the mid Eocene age at 70, 

 from the examination of the fossil plants. 



General Conclusions. 



It is impossible for the reader who has followed these 

 three stages of the Eocene period not to be impressed 

 with the extraordinary character of the mammalia. They 

 stand in the same relation to living species that the main 



1 In Fig. 5 I have chosen the Galago as the representative of the 

 Eocene lemurs. 2 Nature, xix. p. 125. 



