190 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Mar. 10, 



Pupa anglica (W.). Vertigo substriata (W.). 



Vertigo palustris (W.E.). Clausilia bidens (W.). 



pusilla (W.E.). nigricans ("W.). 



edentula (W.E.). Rolphii (W.). 



pygmsea (W.). Achatina acicula ? (W.). 



angustior (W,). Carychium minimum (W.E.). 



alpestris (W.). Acme fusca, and var., reversed (W.). 



Freshwater Shells. 



Succinea putris (W.E.). Planorbis nitidus (W.). 



Pfeifferi (W.E.). albus (W.). 



Limneus truncatulus (W.E.). vortex (W.). 



pereger (W.). Bithinia tentaculata (W.E.). 



palustris (W.E.). ventricosa (W.). 



stagnalis ? (W.). Valvata piscinalis (W.E.). 



Physa hypnorum (W.). cristata (E.). 



Planorbis spirorbis (W.E.). Pisidium obtusale (E.). 



contortus (W.). pulchellum (E.). 



marginatus (W.). pusillum (W.). 



imbricatus (W.). Unio or Anodon, fragments of, ? (W.). 



Entomostraca. 

 Valves of Candona lucens (W.). 



In this marl the horn-core and bones of Ox, antlers of Stag, and 

 bones of Elephant have been met with. 



It may be observed that the shell-marl does not appear to be of 

 much use to the agriculturist as a top-dressing, it having failed to 

 produce the effects which result from the application of chalk to the 

 land. 



Figures of the two extinct land-shells above-mentioned are given 

 in the accompanying woodcut, fig. 4. 



Fig. 4. — Extinct Shells from the Freshwater Beds at Copford. 



^ 



a b c d e 



a—c. Helix incamata. d, e. Helix ruderata (magnified). 



Overlying the white marl is an unstratified deposit of reddish- 

 brown clay (No. 1 of the section), containing chalk-nodules, rounded 

 and angular flints, boulders of greywether and other sandstones, 

 limestones, conglomerates, and porphyritic rocks. This clay is from 

 1 to 6 feet thick ; the greatest thickness occurring in the northern 

 part of the field. To the south it passes over the limit of the marl- 

 beds, and rests on the yellow bed into which the blue clay or brick- 

 earth passes. No organic remains have been found in this brown 

 clay, excepting a molar tooth of a Horse, and this was obtained near 

 its junction with the white marl. 



At the western and northern parts of the field there is a superficial 

 bed of peat, about 1 foot in thickness, with recent land and fresh- 

 water shells, many of which retain their epidermis. 



