. Bulletins of American paleontology. Cambrian Trilobites, South Dakota 259 The metaprotaspid stage differs from the anaprotaspid in hav- ing the axial lobe well delimited by a dorsal furrow and the presence of five glabellar segments. The frontal pits are elongate, and the shield becomes roundly subquadrate. Paraprotaspid stage (PL 2, jigs. 7-15; Text-jig. 2D). — The shield is roundly quadrate to oval in outline, convex, and about mm in length (sag.). The axial lobe is cylindrical, ex-. Text-figure 2. Growth series of Blountia nixonensis Lochman. A. Anapro- taspis, X 36; B, C. Metap
. Bulletins of American paleontology. Cambrian Trilobites, South Dakota 259 The metaprotaspid stage differs from the anaprotaspid in hav- ing the axial lobe well delimited by a dorsal furrow and the presence of five glabellar segments. The frontal pits are elongate, and the shield becomes roundly subquadrate. Paraprotaspid stage (PL 2, jigs. 7-15; Text-jig. 2D). — The shield is roundly quadrate to oval in outline, convex, and about mm in length (sag.). The axial lobe is cylindrical, ex-. Text-figure 2. Growth series of Blountia nixonensis Lochman. A. Anapro- taspis, X 36; B, C. Metaprotaspides, X 30, X 28; D. Paraprotaspis, X 28; E, F. Small and large-sized early meraspid cranidia, X 20, X 15; G. Late mera- spid cranidium, X 12; H. Holaspid cranidium, X 6; I. Holaspid librigena, X 30; J. Holaspid pygidium, X 5 (all drawings were made from photo- graphs.). 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 Paleontological Research Institution (Ithaca, N. Y. ); Columbia University. Ithaca, N. Y. , Paleontological Research Institution [etc. ]
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