. The Cyathaspididae; a family of Silurian and Devonian jawless vertebrates. Cyathaspididae. DENISON: THE CYATHASPIDIDAE 425 Diagnosis.—The dorsal shield is relatively broad and weakly vaulted. There is no median process on the rostral margin, but the. Fig. 147. Homalaspidella borealis (from Denison, 1963); ventral shield, Prince- ton 17092 (X 4). preorbital processes are strongly developed. Narrow, downwardly directed lateral laminae extend from the orbits to the branchial openings and are separated from the rest of the shield by sharp an- gulations. There are no postbranchial lobes, and the
. The Cyathaspididae; a family of Silurian and Devonian jawless vertebrates. Cyathaspididae. DENISON: THE CYATHASPIDIDAE 425 Diagnosis.—The dorsal shield is relatively broad and weakly vaulted. There is no median process on the rostral margin, but the. Fig. 147. Homalaspidella borealis (from Denison, 1963); ventral shield, Prince- ton 17092 (X 4). preorbital processes are strongly developed. Narrow, downwardly directed lateral laminae extend from the orbits to the branchial openings and are separated from the rest of the shield by sharp an- gulations. There are no postbranchial lobes, and the postero-lateral corners of the shield are small points. The posterior edge of the dor- sal shield is nearly transverse except for a small, median, projecting scale that is incorporated. No epitega are distinguishable. Ariaspis ornata Denison. Figures 148-149. Ariaspis ornata Denison, 1963, Fieldiana: Geol., 14, no. 7, pp. 120-123, figs. 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 Denison, Robert H. (Robert Howland), 1911-1985; Chicago Natural History Museum. Chicago : Chicago Natural History Museum Press
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