. Elements of geology. Geology. have either these notches or canals, and all these species are, without exception, carnivorous ; v^hereas nearly all testacea hav- ing entire mouths, are plant-eaters, whether the species be marine, freshwater, or terrestrial. There is, however, one genus which affords an occasional exception to one of the above rules. The Cerithium (Fig. 42.,) although provided with a short canal, comprises some species which inhabit salt, others brackish, and others fresh water. Among the fossils very common in freshwater deposits, are the shells of Cypris, a minute crustaceou
. Elements of geology. Geology. have either these notches or canals, and all these species are, without exception, carnivorous ; v^hereas nearly all testacea hav- ing entire mouths, are plant-eaters, whether the species be marine, freshwater, or terrestrial. There is, however, one genus which affords an occasional exception to one of the above rules. The Cerithium (Fig. 42.,) although provided with a short canal, comprises some species which inhabit salt, others brackish, and others fresh water. Among the fossils very common in freshwater deposits, are the shells of Cypris, a minute crustaceous animal, having a shell much resembling that of the bivalve mollusca.* Many minute living species of this genus swarm in lakes and stagnant pools in Great Britain; but their shells are not, if considered separately, conclusive as to the freshwater origin of a deposit, because another kindred genus of the same order, the Cytherina of Fig. 49. Fig. Chara medicaginula ; Chara elastica ; recent. Italy. fossil. Isle of Wight, a, Sessile seed-vessel between the division of the a, Seed-vesels, leaves of the female plant. magnified 20 6, Transverse section of a branch, with five seed- diameters, vessels magnified, seen from below upwards. h. Stem magnified. ? See figures in chap, on Wealden, Part 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 Lyell, Charles, Sir, 1797-1875; Gibbes, Lewis Reeve, 1810-1894, former owner. DSI; Merrill, George P. (George Perkins), 1854-1929, former owner. DSI. Philadelphia : James Kay, Jun. and Brother ; Pittsburgh : C. H. Kay & Co.
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Keywords: ., bookauthorlyellcharlessir17, bookcentury1800, booksubjectgeology
