. Elements of geology : a text-book for colleges and for the general reader. Geology. 432 MESOZOIC ERA—AGE OF REPTILES. then the curved Gyroceras, then the coiled Nautiloids, then the simple suture became angled in Goniatite, then scalloped in Ceratite, and finally complexly frilled in Ammonite. It is remarkable, however, that one of the simpler forms, viz., the nautiloids, although also one of the earliest, has outlived them all. The corresponding figures on the left are sections showing the position of the siphuncle. The order in which these several genera appeared, and their contin- uance,
. Elements of geology : a text-book for colleges and for the general reader. Geology. 432 MESOZOIC ERA—AGE OF REPTILES. then the curved Gyroceras, then the coiled Nautiloids, then the simple suture became angled in Goniatite, then scalloped in Ceratite, and finally complexly frilled in Ammonite. It is remarkable, however, that one of the simpler forms, viz., the nautiloids, although also one of the earliest, has outlived them all. The corresponding figures on the left are sections showing the position of the siphuncle. The order in which these several genera appeared, and their contin- uance, are shown in the diagram (Fig. 669) on page 434. Belemnites.—The Belemnite (/3eAe/xvov, a dart) was nearly allied to the squid and cuttle-fish of the present day. Like the squid, it had an internal bone (the pen of the squid), except that the bone is much larger and heavier in the Belemnite. It is this bone, or the lower portion of it, which is usually fossilized (Figs. 664-667). When perfect it is expanded and hollow at the upper end, and in the hollow is a small, conical,. 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 LeConte, Joseph, 1823-1901. New York : D. Appleton and Co.
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectgeology, bookyear1892
