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 ZOOLOGY MOLLUSCS The number of species of Mollusca recorded for Hertfordshire is 96. There being 139 known for the whole of the British Islands, this is a fair average, and the number will doubtless be increased when more attention has been paid to the slug fauna, several well-known forms that should be met with not being yet recorded. The Roman snail (Helix pomatia), a very local species, occurs in several localities, in some of which it is probably indigenous ; whilst into others it may have been introduced. It certainly lived in Britain in pre- Roman times. The pretty little Vertigo moulinsiana is at present found in the living state in but a few isolated localities ; two of these however are within the Hertfordshire area. The chief sources of information on the Mollusca of Hertfordshire are three papers read before the Hertfordshire Natural History Society in I884, 1 lists of species collected at field meetings of this Society and published in the Transactions, and a list of species collected in the neigh- bourhood of Hertford by members of the Haileybury Natural History Society. 2 Specimens of nearly all the species here recorded may be seen in the County Museum at St. Albans and in the Haileybury College Museum. A. GASTROPODA I. PULMONATA Vitrea glabra (Brit. Auct.) cellar'ia (Mall.) a. STYLOMMATOPHORA _ nMMa (Drap<) Testacella scutulum, Sby. Hemel Hempstead pura (Aid.) Umax maximus, Linn. radiatula (Aid.). Hitchin ; Berry Wood, fla-vus, Linn. Aldenham ; Ware arborum, Bouch. -Chant. nitida (Mull.). Hitchin ; Ware Agriolimax agresth (Linn.) fulva (Mull.) Icevh (Mall.). Ware Arion ater (Linn.) Amalia sowerbii (Fei.). Verulam Hills, St. kortensis, Fer. Albans ; Ware Punctual pygmisum (Drap.). Hitchin ; Hoddes- Vitrina pellucida (Mttll.) don Fields Vitrea crystallina (Mall.) Pyramidula rupestris (Drap.). Near Bushey alliaria (Miller). Hitchin ; Gallows Hill, Lodge, Watford Haileybury rotundata (Mull.) 1 Roebuck and Taylor, ' The Recorded Occurrences of Land and Freshwater Mollusca in Hertford- shire,' Trans. Herts Nat. Hist. Soc. t vol. iii. p. 10 ; Hopkinson, 'Remarks on the Land Mollusca,' op. clt. p. 17 ; and 'List of Land and Freshwater Mollusca observed in Hertfordshire,' of. ctt. p. 29. I 8l G
 * Fauna and Flora of Haileybury, part i. (1888).