. The ancient life-history of the earth; a comprehensive outline of the principles and leading facts of palaeontological science. Paleontology. I04 HISTORICAL PALEONTOLOGY. but united together in different ways into a common mass. Simple corals, therefore, are the skeletons of siiigle and inde-. Fig. 43. — Zaphrentis Stokesi, a simple "cup-coral," Upper Silurian, Canada. (After Billings.) Fig. 44.—Upper surface of a mass of Stronibodes pentagotius. Upper Silurian, Canada. (After Billings.) pendent polypes; whilst compotmd corals are the skeletons of a;ssemblages or colonies of simila
. The ancient life-history of the earth; a comprehensive outline of the principles and leading facts of palaeontological science. Paleontology. I04 HISTORICAL PALEONTOLOGY. but united together in different ways into a common mass. Simple corals, therefore, are the skeletons of siiigle and inde-. Fig. 43. — Zaphrentis Stokesi, a simple "cup-coral," Upper Silurian, Canada. (After Billings.) Fig. 44.—Upper surface of a mass of Stronibodes pentagotius. Upper Silurian, Canada. (After Billings.) pendent polypes; whilst compotmd corals are the skeletons of a;ssemblages or colonies of similar polypes, living united with one another as an organic community. In the general details of their structure, the Lower Silurian Corals do not differ from the ordinary Corals of the present day. The latter, however, have the vertical calcareous plates of the coral ("septa") arranged in multiples of six or five; whereas the former have these structures arranged in multiples of four, and often showing a cross-hke disposition. For this reason, the common Lower Silurian Corals are separated to form a distinct group under the name of Rtigose Corals or Rugosa. They are further distinguished by the fact that the cavity of the coral (" visceral chamber ") is usually subdivided by more or less numerous Juvizontal calcareous plates or partitions, which divide the coral into so many tiers or storeys, and which are known as the "tabulae" (fig. 45). In addition to the Rugose Corals, the Lower Silurian rocks contain a number of curious compound corals, the tubes of which have either no septa at all or merely rudimentary ones, but which have the transverse partitions or " tabulae " very highly developed. These are known as the Tabulate Corals ; and recent researches on some of their existing allies (such as Heliopora) have sho\vn that they are really allied to. Please note that these images are extracted from scanned page images that may have been d
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Keywords: ., bookcentur, bookdecade1870, booksubjectpaleontology, bookyear1876
