. Cassell's natural history. Animals; Animal behavior. Z, d FAMILY XVI.— The shells of this family are conical or globtdar, with a thick olive-green epidermis ; tlie aperture of the shell is rounded and entire; the operculum is horny, or shelly and concentric. The animal has ji liroad muzzle ; the eyes are placed on short pedicels outside the tentacles, which are long and slender. The Pahidiuidce inhabit fresh water in all parts of the world. The animal of Paludina has a small lobe on each side of its neck. It has a ^ ~/ long muzzle and very short eye pedicels. ^ 'sB The shell is t
. Cassell's natural history. Animals; Animal behavior. Z, d FAMILY XVI.— The shells of this family are conical or globtdar, with a thick olive-green epidermis ; tlie aperture of the shell is rounded and entire; the operculum is horny, or shelly and concentric. The animal has ji liroad muzzle ; the eyes are placed on short pedicels outside the tentacles, which are long and slender. The Pahidiuidce inhabit fresh water in all parts of the world. The animal of Paludina has a small lobe on each side of its neck. It has a ^ ~/ long muzzle and very short eye pedicels. ^ 'sB The shell is thin, turbinated, umbilicated ; LixGi-AL TEETH OF iMf S- F- ii''"Hio .,,-,1 ) tliB splrc is produccd ] the whorls are round and smooth. The development of the gill-bearing Gasteropods may be easily seen in the common River Snail (Ffdudina vivipara), which bring forth their young alive, and whose oviducts in early summer contain young in all stages of growth, some being a quarter of an inch in diameter. Embryos hardly visible to the naked eye have a well-formed shell, ornamented with epidermal fringes, a foot, and operculum. The head has long and delicate tentacles, and very distinct black eyes. Any one who is interested in mollusca may watch this for himself, as Paludina is common in our ditches and marshy waters. Sixty .species are described as abundant in rivers and lakes throughout the Northern Hemisphere, Africa, India, China, Manila, and else- where. Valvata piscinalis is a little fresh-water mollusc, which has the foot divided in front into two lobes. The shell is round and hoinj, much shorter than Paludina or Bithynia. The animal deposits hei eggs in a little leather bag, which she hangs on stones oi tlit stems of water-plants, where they remain till they are hate lit d, and liberated from their bag by the bursting of its rotting sides They all leave their prison in company, being united in a tloatini, mass of jelly. The Amjmllaria, ov "Apple Snai
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Keywords: ., bookcentury1800, bookdecade1890, booksubjecta, booksubjectanimals
