PULMONATA. 81 



The fossil species are very few. Two only have hitherto been described ; both from 

 the Pleiocene formations, and both referred to living forms, viz., S.putris and 8. oblonga, 

 from the Mammaliferous Crag, (Wood's ' Crag. Moll.,' p. 5). The latter species is also 

 given by M. Nyst, (' Coq. Foss. de Belg.,' p. 446,) as occurring in the corresponding 

 formation in Belgium. 



No. 29. Succinea imperspicua. 8. Wood. Tab. XI, fig. 3 a — d. 

 S. imperspicua, S. Wood. 1847. Lond. Geol. Jour., vol. i, p. 118. 



8. testa ovatd, ventricosd, tenui, Icevi ; spirct brevissimd, obtusd: anfractibus tribus, 

 convexis, ad suturam sub-depressis : aperturd rotundato-ovatd, sub-verticali, bessem totius 

 testes in longiiudinem superanti. 



This exceedingly rare shell is thin, smooth, ovate, and composed of three 

 ventricose volutions, rather depressed at the suture. The spire is very short and 

 obtuse ; the aperture large, nearly vertical, and in length fully equal to two thirds of 

 the whole shell. 



I have three specimens only of this shell : two from Hordwell, for which I am 

 indebted to Mr. S. Wood ; the third is from Headon Hill. 



Size. — Axis rather more than 2-10ths of an inch ; diameter, 3-10ths of an inch. 



Section |3. Aquatica, Fleming. 



Limnophila, Eartm. 

 Hygrophila, Fe'russ. 



Family — Ltmn^id^:. 



Genus 12th. Limn^a.* Lamarch. 



Buccinum, (sp.,) Muller, 1774. 



Bulimus, (sp.,) Scopoli, 1777; Bruguiere, 1792. 



Ltmnea, Lamarck, 1801 ; Risso, 1826 ; Valenc, 1833. 



Limneus, Draparnaud, 1805; Brogniart, 1810. 



Lymneus, Brard, 1809; B'Orb., 1841. 



Lymnus, Montfort, 1810. 



LiMNiEA, DeFerussac, 1821 ; Nillson, 1822; Grateloup, 1838; Bronn, 1838. 



LiMNiEES, Oken, 1815; Rossmasler, 1835; Turton, 1831. 



Stagnicola, Leach, 1820. 



Gulnaria, Leach, 1820. 



* Etym., Aiftva'tos, belonging to, or growing in, pools or marshes. 



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