. The ancient life-history of the earth; a comprehensive outline of the principles and leading facts of palaeontological science. Paleontology. 88 HISTORICAL PALEONTOLOGY. lived type. The LingidellcB and their successors, the LingulcB, are singular in possessing a shell which is of a horny texture, and contains but a small proportion of calcareous matter. In the Upper Cambrian Rocks, the Z/;z^/^/<?//<^ become much more abundant, the broad satchel - shaped species known as Z. Davisii (lig. 32, e) being so abundant that one of the great divisions of the Cambrian is termed the " Lingul
. The ancient life-history of the earth; a comprehensive outline of the principles and leading facts of palaeontological science. Paleontology. 88 HISTORICAL PALEONTOLOGY. lived type. The LingidellcB and their successors, the LingulcB, are singular in possessing a shell which is of a horny texture, and contains but a small proportion of calcareous matter. In the Upper Cambrian Rocks, the Z/;z^/^/<?//<^ become much more abundant, the broad satchel - shaped species known as Z. Davisii (lig. 32, e) being so abundant that one of the great divisions of the Cambrian is termed the " Lingula ; Here, also, we meet for tbe first time with examples of the genus Orihis (fig. 32,7^ k^ I) a characteristic Palaeozoic type of. Fig. 32.—Cambrian Fossils : a, Protospongiafenestrata, Menevian Group; h, Areni- coUtesdidyvius, Longmynd Group ; c, Lingjilella femigi^iea, Longmynd and Menevian, enlarged; d, Hymenocaris verjuicanda, Lingula Flags; e, Li7igiilella Davisii^ Lingula Flags ;y, Orthis lenticuiaris, Lingula Flags; g, Theca Davidii, Tremadoc Slates; h, Modiolopsis Solverisis, Tremadoc Slates; i, Obolella sagittalis, interior of valve, Mene- vian ; y, Exterior of the same ; k, Orthis Hicksii, Menevian ; /, Cast of the same ; ni, Olerius muntrtis, Lingula Flags. (Alter Salter, Hicks, and Davidson.) the Brachiopods, which is destined to undergo a vast extension in later ages. Of the higher groups of the Mollusca the record is as yet but scanty. In the Lower Cambrian, we have but the thin, fragile, dagger - shaped shells of the free - swimming oceanic Molluscs or '' Winged-snails " {Fkropoda), of which the most characteristic is the genus T/ieca (fig. 7,2, g). In the Upper Cambrian, in addition to these, we have a few Univalves {Gasteropoda), and, thanks to the researches of Dr Hicks, quite a small assemblage of Bivalves {Lamelhbra?ichiata), though these are mostly of no great dimensions (fig. 32, h). Of the chambered Cephalopoda (Cuttle-fishes and their
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Keywords: ., bookcentur, bookdecade1870, booksubjectpaleontology, bookyear1876
