A HISTORY OF ESSEX Helix bortensis, Mttll. Buliminus montanus (Drap.). ' Essex ' (Brit. Mus.) etscurus (Mall.) Cocblicopa lubrica (Mall.) Azeca tridens (Pult.) Ctectlianella acicula (Mall.) Pupa cylindracea (Da C.) muscorum (Linn.) Sphyradium edentulum (Drap.) Vertigo anti-vertigo (Drap.) substriata (Jeff.) pygm* a (Drap.) moulinsiana (Dup.). Roydon pusilla, Mull. Bardfield (?) Balea pervena (Linn.) Clausilia laminata (Mont.) bidentata (Strom.) Succinea putris (Linn.) elegans y Risso. b. BASOMMATOPHORA Carychium minimum, Mall. Melampus denticulatus (Mont.). River Colne, Wyvenhoe Alexia myosotii (Drap.). Grays ; Purfleet ; Dovercourt Leuconia bidentata (Mont.). Brightlingsea ; Dovercourt Ancylus ftuviatilis, Mall. Velletia lacuitris (Linn.) Limntea auricularia (Linn.) pereger (Mall.) palustris (Mull.) truncatula (Mall.) stagnalis (Linn.) glabra (Mall.). Woodford ; Barking Side ; Colchester Planorbis corneus (Linn.) albus, Mull. g/aber, Jeff. Carswell Pond ; Dagenham nautileus (Linn.) carinatus, Mall. marginatus, Drap. vortex (Linn.) spirorbis, Mall. contortus (Linn.) fontanus (Lightf.) lineatus (Walker) Physa fontinalis (Linn.) hypnorum (Linn.) II. PROSOBRANCHIATA Paludestrina confusa (Frau.). Becton (probably now extinct) jenkinsi (Smith). Becton ; Rainham ; Tilbury ventrosa (Mont.). Coldharbour Point to Tilbury ; Thurrock Marsh ; between Walton and Thorpe-le-Soken stagnalis (Bast.). Grays ; Tilbury ; Wy- venhoe ; Colchester Bithynia tentaculata (Linn.) leachii (Shepp.) V'mipara vivipara (Linn.) contecta (Millett). Old River Lea ; Col- chester ; River Stour Valvata piscina/is (Mall.). cristata, Mttll. Assiminea grayana, Leach. Grays and other spots along the Thames ; River Colne, Colchester. (Becoming extinct) Pomatias elegans (Mull.). Felstead ; Coggles- hall ; Saffron Walden ; Wicken Bon- hunt ; Belchamp Neritina flwviatilii (Linn.). B. PELECYPODA Dreissensia polymorpha (Pall.). River Lea Unto pictorum (Linn.) tumulus, Retz. Anodonta cygneea (Linn.) Spharium rivicola (Leach). River Stort corneum (Linn.) male (Fir.). Woodford Spkterium lacustre (Mall.) Pisidium amnicum (Mall.) pusillum (Gmel.) nitidum, Jenyns. Colchester fontinale (Drap.) milium (Held.). Lea Marshes 90
