THE NEW DOMESDAY 253 



of accommodation. Any contributions towards the enlargement 

 fund will be very gratefully accepted by the author of this volume. 



As an instance of the present status of the Society, it may here 

 be mentioned that it is affiliated to the British Association, 

 Hertfordshire Natural History Society, School Nature Study 

 Union, Selborne Society, the South-Eastern Union of Scientific 

 Societies, and the Watson Botanical Exchange Club. 



Letchworth museum is, to an extent, mapped out on the 

 space-for-time principle, so ably illustrated at the educational 

 museum at Haslemere founded by the late Sir Jonathan Hutchin- 

 son, but whilst it has not been possible in the room at disposal 

 to carry this out in its entirety at Letchworth, an attempt has 

 been made in a series of six mahogany cases. A coloured chart 

 shows the comparative duration of the geological periods illus- 

 trated by these six wall cases. 



The cases illustrate the development of life on the earth from 

 the earliest geological records to the present day. For con- 

 venience, the space behind each glass door is here referred to as 

 one case, and numbered I. -VI. from the left. The last two of 

 these cases are devoted to remains almost all local of the 

 Human Race, first in the " Stone Ages," then in the " Bronze " 

 and " Iron " Ages, thus bringing the record of man up to historical 

 times. 



It should be noted that the fossil exhibits are arranged in 

 ascending scale of life, from the Sponges, Corals, and Sea-Urchins 

 of the lowest shelf, to the Vertebrates or Backboned Animals 

 of the top shelf (in which, however, Vegetable forms are also 

 included). It is thus possible to study more easily the develop- 

 ment of a particular class or family, e.g. the Brachiopods, or the 

 Ammonites, through successive geological eras. 



Cases I. -III. correspond broadly with the three great geological 

 eras : Palceozoic, Mesozoic, and Tertiary, giving special promi- 

 nence to the Chalk Age (a subdivision of the Cretaceous period 

 of the Mesozoic era) as being the local " formation " that is, 

 the ground beneath us dates from this age, as may be seen from 

 the " section " map displayed. A series of reconstructed maps 

 inside the cases shows the successive rise and fall of the land 

 surface of what is now the British Isles, which has caused these 

 remains to be accumulated beneath the sea, and preserved by 

 the sediment falling upon them. 



Case IV. is devoted to local remains from the " Boulder -clay " 

 and " drift gravels " which have been transported by ice, and 



