. The ancient life-history of the earth; a comprehensive outline of the principles and leading facts of palaeontological science. Paleontology. THE JURASSIC PERIOD. 233 foreign body by means of a jointed stem, from which they detach themselves when fully grown to lead an independent existence. In this later stage of their life, therefore, they closely resemble the Brittle-stars in appearance. True Star- fishes {Asteroids) and Brittle-stars (yOphiuroids) are abundant in the Jurassic rocks, and the Sea-urchins {Echinoids) are so numerous and so well preserved as to constitute quite a marked feat
. The ancient life-history of the earth; a comprehensive outline of the principles and leading facts of palaeontological science. Paleontology. THE JURASSIC PERIOD. 233 foreign body by means of a jointed stem, from which they detach themselves when fully grown to lead an independent existence. In this later stage of their life, therefore, they closely resemble the Brittle-stars in appearance. True Star- fishes {Asteroids) and Brittle-stars (yOphiuroids) are abundant in the Jurassic rocks, and the Sea-urchins {Echinoids) are so numerous and so well preserved as to constitute quite a marked feature of some beds of the series. All the Oolitic urchins agree with the modern Echinoids in having the shell composed of no more than twenty rows of plates. Many different genera are known, and a characteristic species of the Middle Oolites {Hemicidaris crenularis^ fig. 163) is here 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 Nicholson, Henry Alleyne, 1844-1899. New York, A. L. Fowle
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Keywords: ., bookcentur, bookdecade1870, booksubjectpaleontology, bookyear1876
