3914 Mollusks. 



which, on examination, is found to be rich in shells, not only of the 

 aquatic species, but of the smaller terrestrial kinds also. Many, per- 

 haps most, are, as might be expected, bleached or imperfect; but still 

 a large number of specimens may be thus obtained, as perfect and 

 transparent as if found alive in their natural abode, although the ani- 

 mal inhabitant has, in general, wholly disappeared : thus sparing the 

 collector the unpleasant business of killing and extracting it. I have 

 been much puzzled to account for this circumstance, as it can hardly 

 arise from gradual decay. Is there any race of insects which prey 

 upon these mollusks, either in a dead or a living state, thus leaving 

 the shells in a beautifully perfect condition ? If so, my cabinet is 

 much indebted to them for their labours. 



I have entirely omitted the slugs from this list, not having collected 

 or studied them ; as well as several of the more obscure species, espe- 

 cially of Zonites and Pisidium, from my not feeling sure of being able 

 to distinguish them in their different stages of growth, though I have 

 but little doubt of their occurrence here. 



Neritina fluviatilis. Numerous in the river, and extremely varia- 

 ble ; when alive, always encrusted with mud, the removal of which 

 appears to destroy the beautiful coloured markings, so ornamental 

 when the shell is found dead and empty. 



Paludina vivipara. Very fine and tolerably abundant in the Stour. 

 I have kept these curious creatures in a pail of water, and had a large 

 accession of young ones, their delicate shells adorned with spines, 

 which disappear as they become mature. 

 Bithinia tentaculata. Common. 



„ ventricosa. Not rare. 

 Valvata piscinalis and cristata. Common. 

 Vitrina pellucida. Now and then found in moss. 

 Helix aspersa. One picked up in my garden had the whorls much 

 produced. 



„ hortensis and nemoralis. Abundant. 



„ hybrida. Two or three specimens I believe to be of this 

 intermediate species. 



„ arbustorum. In some moist mossy hedges near the town. 

 „ lapicida. Not uncommon. 



„ pulchella. Excessively abundant in the drift, and, I think, 

 inhabiting the meadow close to the river. 



„ Cantiana. Common on the chalky banks, white, pale pink, 

 and of a rufous colour. 



