GASTEROPODA. 7 



the water is brackish. The species found in the Crag are, however, such as in the 

 present day are frequenters of ponds and ditches, and were in all probability conveyed 

 to their present locality as dead and empty specimens. Hitherto this genus has not 

 been found in any older formation than the Eocene, during which period it lived and 

 flourished in great profusion. 



1. LIMN^A PALUSTRIS (?) Linn. Tab. I, fig. 9, a d. 



HELIX PALUSTRIS. Gmel. Syst. p. 3658, 1782. 



LIMNEUS PALUSTEIS. Drap. Hist. Nat. desMoll. ter. et fluv. p. 52, tab. 2, fig. 40, 1805. 



HELIX PALUSTRIS. Mont. Test. Brit. p. 373, t. 16, fig. 10, 1803. 



LYMN^A TENUIS. Woodward. Geol. of Norf. t. 3, fig. 30, 1833. 



LIMNEUS PALUSTRIS. Gray. 2d edit. Turt. p. 239, fig. 107, 1844. 



LYMNEUS PALUSTRIS. S. Wood. Catalogue 1842. 



L. Testa clongato-ovatd, tenui : spird elevatd, apice acuto ; anfractibus 4 5 converts, 

 lavigatis ; aperturd ovatd. 



Shell elongato-ovate, thin, with an elevated spire and acute apex ; whorls about 

 five, convex and smooth, aperture ovate, half the length of shell. 



Axis, | of an inch. 



Locality. Mam. Crag, Bramerton and Bulcham. Recent, Britain. 



Two or three belonging to Mr. Lyell, with one of my own, are all the fossil 

 specimens that I have been able to examine ; they do not satisfactorily agree with the 

 above recent species, although they resemble it more than any other with which I am 

 acquainted, and present a sort of intermediate form between it and L. pereger, having the 

 elevated spire of L. palustris and the convex whorls of L. pereger, or perhaps more 

 like gigantic specimens of L. truncatulus. The left lip, which in the recent shell is a good 

 deal reflected, is broken away in the Crag specimens, showing a small umbilicus. 

 This species I have found at Stutton and Clacton, precisely resembling the recent form. 



2. LIMN^A PEREGRA. Mull. Tab. I, fig, 7, a b. 



BUCCINUM PEREGRUM. Mull. Verm. p. 130, No. 324, 1774. 

 BULIMUS PEREGER. Sruffuiere. Diet. No. 10, 1789. 

 LIMNEUS PEREGER. Drap. Moll. pi. 2, fig. 34-37, 1805. 

 HELIX PEREGRA. Mont. Test. Brit. 1803. 



LIMN^EUS VULGARIS. Rossmasler. Icon. p. 97, t. 2, fig. 53-54, 1835. 

 PEREGER. S. Wood. Catalogue 1842. 



L. Testa ovato-oblongd, tenui, fragili ; anfractibus quatuor, convexis ; suturis profundis ; 

 spird mediocri, acutd ; labio reflexo, aperturd ovatd. 



Shell ovato-oblong, thin, and fragile, with four convex volutions and a deep suture ; 

 moderately elevated spire, and acute apex ; aperture elongato-ovate, with a subreflected 

 peritreme ; left lip covering the umbilicus. 



Axis, \ an inch. 



Locality. Mam. Crag, Southw r old and Bramerton. Recent, Britain. 



One specimen of my own, with a few belonging to Mr. Wigham, obligingly sent to 



