35 



NOTE ON A HOLOCENE DEPOSIT AT PENTON HOOK; 



By J. E. Cooper. 



Read 9th December, 1921. 



The section here described is at the middle of the U-shaped bend of 

 the Thames at Penton Hook, on the Middlesex bank. Mr. W. J. 

 Wintle called my attention to it some years ago, and if he had 

 remained in London he would probably have described it. 



The river bank is here about 7 feet above the normal water-level ; 

 a section in the centre shows : — 



Thin turf 



Brick earth with a few shells . 



Coarse gravel and sand . 



Fine gravel and sand with Plan. 



stroemii, and abundance of shells 

 Thin bed of fine sand without shells 

 Base hidden by talus, probably stiff 



clay as shown in the river bank 



close by . 



The following mollusca were collected from the shell-bed containing 

 Planorbis stroemii : — ■ 



A few inches. 

 About 2 feet. 

 About 15 inches. 



About 18 inches. 



A few inches. 



Vitrea crystallina (MiilL). 

 Polita niticlula (Drap.). 

 Goniodiscus rotundatus (MiilL). 

 Hygromia hispida (L.). 

 H. striolata (C. Pfr.). 

 Vallonia excentrica Sterlci. 

 Helicigona arbustorum (L.). 

 Helix nemoralis L. 

 H. hortensis Mull. 

 Cochlico'pa luhrica (Miill.). 

 Pupilla muscorum (L.). 

 Succinea putris (L.). 

 S. elegans, Risso. 

 Ancylus fluviatilis, Miill. 

 Limncea auricularia (L.). 

 L. pereger (Miill.). 

 L. palustris (Miill.). 

 L. truncatula (Miill.). 

 L. stagnalis (L.). 

 Planorbis corneus (L.). 

 P. albus Miill. 

 P. stroemii West. 

 P. crista (L.). 

 P. carinatus Miill. 



P. wnbilicatus Miill. 



P. vortex (L.). 



P. leucostoma, Millet. 



P. contortus (L.). 



Bithynia tentaculata (L.). 



B. leachi (Shepp.). 



Vivipara vivipara (L.). 



V.fasciata (MiilL). 



Valvata piscinalis (MiilL). 



V. cristata Miill. 



Theodoxus fluviatilis (L . ) . 



Unio pictorum (L.). 



U. tumidus_T^etz. 



Anodonta anatina (L.). 



Pseudanodonta elongata Hoi. 



Spkcerium corneum (L.). 



Pisidium amnicum (MiilL). 



P. supinum A. Schm. 



P. subtruncatum Malm. 



P. cinereum Alder. 



P. obtusalastrum B. B. Woodw. 



P. nitidum Jenyns. 



P. milium Held. 



P. torquatum Stelf . 



