A manual of the Mollusca, or, A rudimentary treatise of recent and fossil shells . rgo no apparent meta-morphosis ; when born, they differ from their parents in size only. Thewater-breathers have at first a small nautiloid shell, capable of concealingthem entirely, and closed by an operculum. Instead of creeping, they swimwith a pair of cihated fins springing from the sides of thehead; and by this means are often more mdely dispersedthan we should be led to expect from their adult habits;thus some sedentaiy species of cahjptrcea and chiton havea greater range than the paper-sailor, or the ever
A manual of the Mollusca, or, A rudimentary treatise of recent and fossil shells . rgo no apparent meta-morphosis ; when born, they differ from their parents in size only. Thewater-breathers have at first a small nautiloid shell, capable of concealingthem entirely, and closed by an operculum. Instead of creeping, they swimwith a pair of cihated fins springing from the sides of thehead; and by this means are often more mdely dispersedthan we should be led to expect from their adult habits;thus some sedentaiy species of cahjptrcea and chiton havea greater range than the paper-sailor, or the ever-driftingoceanic-snail. At this stage, w^hich may faiily be compared with thelai-val condition of insects, there is scarcely any differencebetween the young of eolis and aplysia, or buccinum andvermetm. (M. Edw.) ^^- ^^^ The development of the branchiferous gasteropods may be observed withmuch facility in the common river-snails {paludina) ; which are viviparous,and whose o^dducts in early summer contain young in all stages of growth;some being a quarter of an inch in
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Keywords: ., bookcentury1800, bookdecade1850, booksubjectmollusks, bookyear185
