The Cambridge natural history . t would be natural to expect that we should lind thisprocess of conversion still going on, and that we should beiible to detect particular species or groups of species in processof emigration from sea to land, or from sea to fresh species will Ije intermediate between a marine and aland or fresh-water species, and difficult to classify distinctlyas one or the other. Cases of Mollusca occupying this interme-diate position occur all over the world. They inhabit brackishswamps, damp places at high-water mark, and rocks only atintervals visited by the tid
The Cambridge natural history . t would be natural to expect that we should lind thisprocess of conversion still going on, and that we should beiible to detect particular species or groups of species in processof emigration from sea to land, or from sea to fresh species will Ije intermediate between a marine and aland or fresh-water species, and difficult to classify distinctlyas one or the other. Cases of Mollusca occupying this interme-diate position occur all over the world. They inhabit brackishswamps, damp places at high-water mark, and rocks only atintervals visited by the tide. Such are Fotamides, Assiminea,Sqolionaria, Melmiqyus, Hydrohia, Truncatella, among the uni-valves, and many species of Cyrena and Area among thel»ivalves. Origin of the Fresh-water Fauna (a) Pelecypoda. — Estuarine species, which have l)ecomeaccustomed to a certain admixture of fresh water, have graduallyascended the streams or been cut off from the sea, and have atlast become habituated to water which is perfectly
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1895
