LIST OF ILLUSTEATIONS. 



PLATES. 



I. Map of Hertfordshii'e showing the Districts into which 



it is proposed to divide the County for the illustra- 

 tion of its Botanical Geography To face p. 65 



II. The Polarisation of Light 7b>ce p. 160 



WOODCrTS. 



PAGE 



Section showing the approximate relative thickness of the 



British Sedimentary Rocks 3 



Map showing the extension of the Cretaceous Rocks in 



England ; 5 



Poraminifera from the Chalk 9 



Eoraminifera from the Atlantic Ooze 9 



Section across the London Tertiary Basin 11 



General Section of the Tertiary Beds at Bushey KilnjWatford 94 



Ditto at Watford Heath Kiln 95 



Ditto at Hatfield Park Kiln . . .. 98 



Ditto at Mr. Lines' Brickyard, near Hertford 99 



General Section on Railway, Bushey Cutting 100 



"Wheat Mildew — Puccinia graminis 232 



Bramble Leaf Brand — Aregma hulbosum 233 



Maple Blight — JJncinula hicornis . . . . 234 



