KENNARD : HOLOCENE NON-MARINE MOLLUSCA OF ENGLAND. 251 



and Blashenwell, Dorset, has not yet been detected living in either 

 county. 



Lauria anglica (Fer.) is now known fossil from Totland Bay 

 (Isle of Wight), Copford, Shalford, and Felstead (Essex), Harlton 

 (Cambridgeshire), Ledbury (Herefordshire), and Askern (Yorkshire), 

 and of these comital divisions it is to-day apparently absent from 

 the first three. 



Vertigo substriata (Jeff.), too, has been found in deposits at 

 Ledbury (Herefordshire), Wilstone (Hertfordshire), Mottisfont 

 (Hampshire), and Totland Bay (Isle of Wight), and is unrecorded 

 living from any of these counties. 



Vertigo moulinsiana (Dupuy) is as yet unknown in a recent state 

 from Gloucestershire, South Essex, and Kent, though occurring 

 fossil at Westbury on Severn, Walthamstow, Chingford, and Deal, 

 whilst the two fossil records for Vertigo alpestris, Aid., Wheatley 

 (Nottinghamshire), and Chignal St. James (Essex), clearly show 

 that this species was once far more widely spread than at present. 



Vertigo pusilla, Miill., has now been detected fossil at Totland 

 Bay (Isle of Wight), Blashenwell (Dorset), Ightham and Crossness 

 (Kent), Tilbury (Essex), Reigate (Surrey), and Southampton and 

 Mottisfont (Hampshire), six divisions which still remain blank in 

 the recent census. 



The former abundance of Vertigo angustior, Jeff., has often been 

 commented upon, for to-day it is one of our rarest shells. It is an 

 abundant species in the early Holocene beds of Copford, Felstead, 

 and Chignal St. James, Essex, and has occurred in a bed of similar 

 age at Harlton, Cambridgeshire, and in neither county has it yet 

 been found living. 



" Truncatellina minutissima (Hart.)," and I use this name for 

 the aggregate species since the value of the suggested segregates 

 has yet to be tested, is only known fossil from Northfleet, Green- 

 hithe, and Cuxton (Kent), near Staines (Berkshire), Westbury 

 (Gloucestershire), and Grimes Graves (Norfolk), and the recent census 

 has no record from any of these counties. 



Planorbis stroemii, Westld., is only known living from one locality 

 in Oxfordshire, yet in the Holocene beds of the Lea and the Thames 

 it is a common species, being known from Berkshire, Buckingham- 

 shire, Essex, Middlesex, Oxfordshire, and Surrey. So far it has not 

 been found in the extensive Holocene beds of the Kennett. This 

 shell was found living in a bed of Chara, and there is nearly always 

 abundant Chara debris in the beds in which it is found. Possibly 

 the cause of the almost total extinction of this species has been the 

 destruction of its natural habitats by the canalization of the rivers 

 and better drainage of the surface waters. 



Acicula lineata (Drap.) is another species common in the early 

 Holocene beds of Essex, and it must have been an abundant species 

 there in former times, a condition of things very different from that 



