. The ancient life-history of the earth; a comprehensive outline of the principles and leading facts of palæontological science. Paleontology. THE CAMBRIAN PERIOD. 85 in some of the Cambrian Trilobites, such as the Httle Agnosti (tig. 31, g), the animal was bhnd. The lateral portions of the. Fig. 31.—Cambrian Trilobites: a, Paradoxides Boheviiciis, reduced in size; h, ElUf>- socep/tahts Hoffi ; c, Sao hirsuta ; d, Conocoryf'he Sultzcf-i (all the above, together with fig. g^, are from the Upper Cambrian or " Primordial Zone " of Bohemia); e. Head-shield oiDikellocephahis Celticiis,
. The ancient life-history of the earth; a comprehensive outline of the principles and leading facts of palæontological science. Paleontology. THE CAMBRIAN PERIOD. 85 in some of the Cambrian Trilobites, such as the Httle Agnosti (tig. 31, g), the animal was bhnd. The lateral portions of the. Fig. 31.—Cambrian Trilobites: a, Paradoxides Boheviiciis, reduced in size; h, ElUf>- socep/tahts Hoffi ; c, Sao hirsuta ; d, Conocoryf'he Sultzcf-i (all the above, together with fig. g^, are from the Upper Cambrian or " Primordial Zone " of Bohemia); e. Head-shield oiDikellocephahis Celticiis, from the Lingula Flags of Wales; f. Head-shield oiCoiio- C07yphe MattJieivi, from the Upper Cambrian (Acadian Group) of New Brunswick; ^, AguostJis rex, Bohemia ; //, Tail-shield o^Dikellocephaliis Mhinesotettsis, from the Upper Cambrian (Potsdam Sandstone) of Minnesota. (After Barrande, Dawson, Salter, and Dale Owen.) head-shield are usually separated from the central portion by a pecuHar line of division (the so-called " facial suture ") on each side; but this is also wanting in some of the Cambrian species. The backward angles of the head-shield, also, are often prolonged into spines, which sometimes reach a great length. Following the head-shield behind, we have a portion of the body which is composed of movable segments or "body- rings," and which is technically called the " ; Ordi- narily, this region is strongly trilobed, and each ring consists of a central convex portion, and of two flatter side-lobes. The number of body-rings in the thorax is very variable (from two to twenty-six), but is fixed for the adult forms of each group of the Trilobites. The young forms have much fewer rings than the full-grown ones; and it is curious to find that the Cam-. 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
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Keywords: ., bookaut, bookcentury1800, bookdecade1870, booksubjectpaleontology
