. The ancient life-history of the earth; a comprehensive outline of the principles and leading facts of palæontological science. Paleontology. 88 HISTORICAL PAL.'EONTOLOGY. lived type. The LingulellcB and their successors, the Lingtilce, 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 Zz>/^///£'//<^ become much more abundant, the broad satchel - shaped species known as Z. Davisii {fig. 32, e) being-so abundant that one of the great divisions of the Cambrian is termed the " Ling
. The ancient life-history of the earth; a comprehensive outline of the principles and leading facts of palæontological science. Paleontology. 88 HISTORICAL PAL.'EONTOLOGY. lived type. The LingulellcB and their successors, the Lingtilce, 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 Zz>/^///£'//<^ become much more abundant, the broad satchel - shaped species known as Z. Davisii {fig. 32, e) being-so abundant that one of the great divisions of the Cambrian is termed the " Lingula ; Here, also, we meet for the first time with examples of the genus OriJiis (fig. 32,/, k^ I) a characteristic Palaeozoic type of. Fig. 32.—Cambrian Fossils : n, Protospojigia fenestraia, Menevian Group; h, Are?n- colitesdidynius, Longmynd Group ; c, Lingulella ferr7igbiea, Longmynd and Menevian, enlarged; d, Hyjueiiocaris vervikaiida, Lingula Flags; e, Lingnlella Davisii, Lingula Flags;/, 6>rM/i-/^«^/c-«/rtr/i-,'Lingula Flags; ..f, Theca Davidii, Tremadoc Slates ; h, Modiolopsis Solvetisis, Tremadoc Slates; /, Obolella sagittalis, interior of valve, Mene- vian ; j. Exterior of the same ; k, Orthis Hicksii, Menevian ; /, Cast of tfie same ; ;;/, Olenus micnirics, Lingula Flags. (Aiter Salter, Hicks, and Davidson.) the Brachiopods, which is destined to undergo a vast extension in later ages. Of the higher groups of the Molhisca 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 " {Pteropoda), of which the most characteristic is the genus Tlieca (fig. 32, 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 {Lamellibnmchiata), though these are mostly of no great dimensions (fig. 32, h). Of the chambered Cephalopoda (C
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Keywords: ., bookaut, bookcentury1800, bookdecade1870, booksubjectpaleontology
