LIST OF ILLUSTRATIONS. 



PLATES. 



I. Vertigo Moidinsiana, D\x]}Vlj Jb /ace p. 81 



II. Eotifera ,, 113 



III. Map of Hertfordshire showing its River Basins and the 



Positionof its Rainfall Stations, 1879-80 .. To face ^. 127 



OTHER ILLUSTRATIONS. 



PAGE 



Gravels of the two Plains of Hertfordshire 104 



Section from the Valley of the Stort, through the Chalk 



Escarpment, to the Yallcy of the Cam 104 



Section showing the Boulder-clay on the top of the Chalk 



Escarpment 105 



Section through the Valley of the Lea 106 



Section through the West of Hertfordshire showing the bare 



Chalk Escarpment 110 



Outline-Map of Hertfordshire, showing Phenological Stations 



and Places at or near to which Observers are required 257 



