IN a former number of NATURE (vol. viii. p. 462), Mr. A. R. Wallace, in reviewing Sir Charles Lyell's last edition of the â Antiquity of Man.â makes use of the rate of deposits of stalagmite as data for ascertaining the age of animal remains which arefound buried in caves. It is evident that the variations of rate will render unreliable data for arriving at correct conclusions; still, calculations based thereon may be of service.