86 NATURAL SCIENCE. ^pril, 



race not contemporary with the valley men, but also that the former 

 belonged to a period considerably anterior to the latter — either an 

 early Glacial or a pre-Glacial period." 



The plateau race referred to by Professor Prestwich in the above 

 quotation, is supposed to have manufactured certain extremely rude 

 implements found at high levels on the Chalk Downs, near Sevenoaks. 

 These implements are thought to be as old as the " plateau drift " 

 which caps the higher part of the Downs. The plateau drift is 

 considered to be older than the oldest of the river-terraces, and older 

 than the Boulder Clay. 



If all these statements are allowed to pass without question, no 

 doubt man is pre-glacial in Britain ; but, unfortunately, many of the 

 supposed flakes yield but doubtful evidence of human agency, and 

 none of them have yet been found more than 2i feet below the 

 surface, though the Drift is said to be from 5 to 20 feet thick. At 

 present, also, there is no evidence that the plateau drift, as we now 

 see it, is in its original state ; but it rather seems that, what with 

 solution of the underlying Chalk, flood action, and other causes, it is 

 almost impossible for the Drift to have remained undisturbed during 

 a long period. 



Professor Prestwich concludes that " the rude implements would 

 appear to have been carried down, with the southern drift, on to the 

 plateau, from those Central Wealden uplands which [he has] esti- 

 mated might, in pre-glacial times, before the denudation of the 

 Weald, have formed a low mountain range 2,000 to 3,000 feet in 

 height." We should be inclined to doubt the existence, during any 

 period, of such a mountain range, formed of soft strata like those of 

 the Weald. Even granting the existence of this mountain chain, 

 and of the floods which swept the Greensand material northward on 

 to the Chalk plateau, it does not necessarily follow that the imple- 

 ments were transported in the same way, or are of contemporaneous 

 date. They may be of much later date, and only accidentally asso- 

 ciated with fragments of Greensand, such as may have been moved 

 and re-deposited, time after time, before coming to rest in the 

 now-existing red clay. 



Professor Prestwich's earlier papers form a most valuable con- 

 tribution towards a study of Palaeolithic man and his tools, but we 

 do not feel satisfied that in these latest memoirs he has advanced our 

 knowledge of the antiquity of the human race in this country. The 

 question still remains as it stood several years ago. 



Two Zoological Fables. 



In 1 719, Leuwenhoek first started the idea that Rotifers, or 

 *' Wheel-animalcules," could be completely dried and kept for years 

 in that condition, and then restored to life by being moistened with 

 water. His conclusions were supported by Spallanzani in 1776 



