. Text book of vertebrate zoology. Vertebrates; Anatomy, Comparative. GNA THOSTOMES. 225 ORDER II. ASPIDOCEPHALI (OSTEOSTRACI). Head covered by a large, simple, arcuate shield much like the cephalothorax of Limtdus in outline, with ' orbits ' near its centre. Tail covered with rhomboid scales of varying size. No paired appendages known. Cephalaspis, Devonian. Auchenaspis, upper Silurian. ORDER III. ANTIARCHA. Head and trunk covered with large polygo- nal plates coated with enamel; tail with small scales, ' orbits' dorsal, close together, a single pair of appendages ('pectoral fins'), covered w
. Text book of vertebrate zoology. Vertebrates; Anatomy, Comparative. GNA THOSTOMES. 225 ORDER II. ASPIDOCEPHALI (OSTEOSTRACI). Head covered by a large, simple, arcuate shield much like the cephalothorax of Limtdus in outline, with ' orbits ' near its centre. Tail covered with rhomboid scales of varying size. No paired appendages known. Cephalaspis, Devonian. Auchenaspis, upper Silurian. ORDER III. ANTIARCHA. Head and trunk covered with large polygo- nal plates coated with enamel; tail with small scales, ' orbits' dorsal, close together, a single pair of appendages ('pectoral fins'), covered with strong plates, and each jointed near the middle. Pierichthys (lower Devonian), 1-4 inches long. Asierolepis, 6 inches long (Devo- nian). Fig. 230. Cephalaspis, from Dean, aftei- 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 Kingsley, J. S. (John Sterling), 1854-1929. New York, H. Holt and Company
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