ALLUVIUM AT WALTHAMSTOW, ESSEX. 1 7 



Planovhis contortus (Linn.) Anodonta cygnaa (Linn.) 



,, fontanus (Lightft.) Sphcevinni corneum (Linn.) 



Physa fontinalis (Linn.) Pisidinm amnicum (Linn.) 



„ hypnovum (Linn.) „ supimim, A. Schm. 



Bithynia tentaculata (Linn.) 



„ leachii (Shepp.) 

 Vivipava vivipava (Linn.) 

 Valvatii piscinalis ( M ii 1 1 . ) 



,, cvistata, Miill. 

 Nevitina flttviatilis (Linn.) 

 Unio tumidiis, Retz. 



hensloiviamtm (Shepp.) 

 SKbtruncatum, Malm. 

 pulchelhtni, Jenyns. 

 pusilliim (Gmel.) 

 nitiduin, Jenyns. 

 ohtusale, Pfr. 

 milium, Held. 



The following species, previously recorded from these beds, 

 we did not find : — 



Acanthinula lamellata (Jeff.) Vivipava contecta (Millet) 



Helicella capevata (Mont.) Unio pictovum (Linn.) 



NOTES ON THE SPECIES. 



Arion ater (Linn). Several calcareous granules representing 

 the internal shell of this species were found. It has not hitherto 

 been detected in these, or in any other Holocene deposit in 

 Essex, though it is known from the Pleistocene of Ilford. 



Of the ten species of Vitrea living in this country, all but 

 three were met with, the exceptions being V. piiva and " glabra " 

 and V. excavata. V. alliaria is represented by a single example, 

 and is of considerable interest, since it has hitherto been only 

 known fossil in these islands from the Pleistocene of Ightham 

 and Happaway Cavern. V. nitidula was very common and is 

 separable into two forms, a larger one attaining a maximum 

 diameter of ii mm., and a smaller one of only 6.5 mm. The 

 latter is known on the Continent under the name of V. nitens 

 (Mich). 



Agriolimax agrestis (Linn) was represented by eight 

 examples. Only a single specimen has hitherto been obtained 

 from these beds. 



Punctum pygmaeum (Drap) has not previously been 

 recorded from the Lea alluvium and now but a solitary example 

 establishes its presence. 



Hygromia granulata (Alder) is another new record for 

 these beds ; but, although several specimens were found, all are 

 immature. 



