2742 Mollusks. 



also nineteen others not included in the above list, making together a total of seventy- 

 nine : twelve of the former still remain either undetected here or confined to other 

 eastern localities. Vertigo palustris and Pisidium Henslowianum have been found 

 by Mr. S. P. Woodward ; but not having been able to procure them now, I have 

 thought it best to record such only as have occurred within the last three or four 

 years. A single specimen of Aplexus Hypnorum I have also seen marked " Laken- 

 ham ; " but as this was doubtful, it too has been excluded : the only place from whence 

 I have obtained it is at Wisbech, in Cambridgeshire, and there it occurred in abun- 

 dance. 



I have given the localities and habitats with the hope of inducing others to ex- 

 amine similar situations, as I feel persuaded that if carefully sought for most of the 

 species will be found to be pretty generally distributed ; and as this highly interesting 

 branch of Natural History has comparatively but few votaries, it is far from impro- 

 bable that more new species still remain to reward the assiduous collector. The rea- 

 diest way to obtain the more minute species inhabiting the land, is to provide a few 

 small linen bags and a sheet of paper (nothing better than an old newspaper), and, 

 in dry weather, to pull up the moss, &c, and shake out the sand and earth from its 

 roots on to the paper : this may then be put into one of the bags, together with a slip 

 of paper noting the spot from whence it was taken, and, being carefully tied up, may 

 be earned home and examined at leisure. In this manner I have obtained some — as 

 Vertigo and Helix pygmsa, Helix crystallina and aculeata, Acme fusca, and several 

 others — which I have never met with in any other way ; and being compelled by my 

 professional avocation to limit tbe extent of my rambles to within a short distance of 

 " home," I have, in consequence, been led to examine more narrowly the few favor- 

 able localities within my reach, which has convinced me that a small field for opera- 

 tion, carefully and repeatedly worked, is infinitely better than a larger district only 

 visited in portions successively. 



Neritina fluviatilis. Abundant on th? submerged leaves of the Nuphar lutea, in 

 the river at Heigham. 



Paludina vivipara. Plentiful in the river and ditches adjoining. 



Paludina Achatina. Common in the river below the city. 



Bithinia tentaculata. Very common. 



Bithinia ventricosa. Sparingly with the Neritina. 



Valvata piscinalis. In ditches, at the roots of aquatic plants. 



Valvata cristata. Occasionally with the above. 



Arion ater. Common ; a chocolate-coloured variety common in the Heigham 

 marshes. 



Arion hortensis. Occasionally met with. 



Limax maximus. Frequent under stones. 



Limax Jlavus. Gardens and cellars. 



Limax ayrestis. Common everywhere. 



Vitrina pellucida. Among damp leaves under hedges, and in almost every wood. 



Testacellus Haliotoideus. In Messrs. Mackie's nursery-gardens : they appear to 

 be thoroughly naturalized, and are found far away from the buildings. Mr. Arthur 

 Mackie informed me that as many as thirty have been taken in one morning. Up- 

 wards of two dozen have been sent to me at one time. 



Helix aspersa. " Too common everywhere." 



Helix hortensis. Common in hedges. 



