270 NATURAL SCIENCE [April 



description of their appearance, surroundings, habits, etc., from their 

 art remains or their written records. I don't know where in fact 

 to draw any rigid line between what is prehistoric and what is 

 historic. Nor do I think the introduction of writing can be accepted 

 as marking a geological horizon. On the other hand, I confess, 

 however paradoxical it may look at first sight, that I know of no 

 better horizon where to divide the beds in question than the in- 

 vasion of the Romans. This, I know, does not sound like a geological 

 test, but it really has a certain geological meaning. It was the 

 Eomans who first began to import into our fauna and flora a great 

 many of our non-indigenous animals and plants, our fruit trees, 

 and also some of oar best known forest trees, our garden plants, and 

 perhaps some of our best known strains of domesticated animals, 

 and if we are to choose a dividing line on biological grounds, I 

 know of none better than this one. To sum up, then, this attempt 

 to arrange the sub aerial beds of England, which intervene be- 

 tween the base of the Forest Bed and to-day, I would condense the 

 result in the following table : — 



I — Older or Forest Bed. 



Anthroijozoic Beds- 



— Theriozoic Beds- 



-The Drift 



-Pre-Roman. 



— Himerozoic Beds- 



/ Younger or Brick Earths 

 \ and Caves. 



-Post-Roman. 



I do not consider that this arrangement and nomenclature in 

 any way interfere with the arrangement and nomenclature of the 

 later beds prevailing in the text books, since it is entirely confined 

 to the subaerial beds which have hitherto been mixed up and con- 

 fused with the submarine beds whose arrangement ought to be 

 dependent on entirely different considerations. To these latter alone 

 the terms Pliocene, older and younger Pliocene, Pleistocene, etc., 

 were originally applied ; and if these terms have any virtue to 

 them they ought to be limited, and I propose to consider them and 

 to fill up some gaps in the present paper on another occasion. In 

 conclusion, it is necessary that I should apologise for the too frequent 

 use of the first personal pronoun in the foregoing pages. It is the 

 inevitable consequence of polemics of this kind. I feel sure it does 

 not mean that I am more cocky and self-asserting and impertinent than 

 the friends I love to criticise, and whose criticisms are so welcome 

 to me. If I did not greatly value their work, mistaken as I deem 

 some of it to be, I should not be creeping away from the House of 

 Commons, at the risk of being abused by the Whips, in order to 

 write this paper. Henry H. Howorth. 



