MOLLUSCS Limntea glabra (Mtill.). Very rare : two speci- mens have been found near Derby Planorbts corneus (Linn.). Plentiful in all the canals in the south of the county a/bus, Mull. Common in the south of the county g/ater, Jeff. Cresswell Crags, in rejecta- menta ; pits at Wellington nauti/eus (Linn.). Cresswell Crags, in rejectamenta carinatus, Mttll. Derby ; Clifton marginatus, Drap. Derby vortex (Linn.). Derby ; Clifton spirorbis, Mttll. Derby contortus (Linn.) fintanus (Lightfoot). Marple ; canals at Derby ; Cromford canal Physa fontinalis (Linn.) Physa bypnorum (Linn.). Rare : canal at Little Eaton ; Darley Dale ; river Dove, near Repton Bithynia tentaculata (Linn.) leachii (Shepp.). Canals at Weston-on- Trent ; Eggington ; Shardlow Vvulpara vivlpara (Linn.). Canals round Derby contecta (Millet). Rare : two specimens in canal at Wellington ; one in the canal at Cromford Valvata piscina/is (Mttll.). Derby ; Crom- ford ; two reversed specimens were found at Cresswell cristata, Mttll. Eggington ; Derby Achilla lineata (Drap.). Cresswell Crags in rejectamenta Neritina fluviatilh (Linn.). Canals at Bor- roughash ; Sawley ; Pyebridge B. PELECYPODA Dreissensia polymorpha (Pall.). Derby and Nottinghamshire canal ; Willington canal ; Butterley Unio pictorum (Linn.). Derby, in canals tumidus, Retz. Canals round Derby ; Repton, where a specimen was found measuring 4f x 2f in., and weighing 4i z - Anodonta cygntea (Linn.). Plentiful in canals round Derby Sphesrium rivicola (Leach). Canal between Shardlow and Chellaston ; Cromford corneum (Linn.) Sphcsrium ovale (Fdr.). Peak Forest canal ; one specimen in the canal near Sawley at its junction with the river Trent lacustre (Mttll.). In canals at Derby and Ambergate Pisidium amnicum (Mttll.) pusillum (Gmel.) nitidum, Jenyns. Cresswell rejectamenta fontinale (Drap.). River Wye Dale and Monsall Dale ; Clifton ; Matlock milium (Held). Clifton Crags, in Ash wood Stanton ; 53
