. The conchology of Nottingham; or, A popular history of the recent land and fresh water Mollusca found in the neighborhood;. Mollusks. 44 Valvata piscinalis (The Stream Valve Shell). Muller. Figures 20 and This abundant fresh-water shell assumes two very distinct forms, so different in appearance from each other that formerly they used to be recorded under two different names. The more stunted form of which was the Valvata depressa of Pfeiffer. From an examina- tion of many specimens, Nilson Grey, and Forbes have each declared the V. depressa to be nothing more than a variation in the sh
. The conchology of Nottingham; or, A popular history of the recent land and fresh water Mollusca found in the neighborhood;. Mollusks. 44 Valvata piscinalis (The Stream Valve Shell). Muller. Figures 20 and This abundant fresh-water shell assumes two very distinct forms, so different in appearance from each other that formerly they used to be recorded under two different names. The more stunted form of which was the Valvata depressa of Pfeiffer. From an examina- tion of many specimens, Nilson Grey, and Forbes have each declared the V. depressa to be nothing more than a variation in the shape of Valvata piscinalis. In the one form the convolutions are produced and the um- bilicus comparatively small, while in the other the con- volutions are depressed, and having a large umbilicus. There are five convolutions, which are somewhat polished, and rather pellucid. The operculum is deep, and tolerably large, and the convolutions are very rounded, the apex being small, but very blunt. The aperture is round and large. It is pale horn-coloured. The size is rather less than a quarter of an inch in diameter, and about a quarter of an inch in height. In one locality in this neighbourhood (the Musco-sic dyke) the shells are mostly covered over with patches of a calcareous deposit, which gives them a mottled appearance. I have not found this deposit on speci- mens taken from any other water besides this brook, and even here only over a space of fifty yards. Valvata piscinalis was first described by Petiver. in his'* Gazophylacium," under the name of Valvata ohtusa. M. Bouchard ' Chautereaux describes this shell as laying, between the months of May and August, from. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Lowe, E. J. (Edward Joseph), 1825-1900. London, C. A. Bartlett; [etc. , etc. ]
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Keywords: ., bookcentury1800, bookdecade1850, booksubjectmollusks, bookyear185
