. The Cyathaspididae; a family of Silurian and Devonian jawless vertebrates. Cyathaspididae. DENISON: THE CYATHASPIDIDAE 317 over the orbits and branchial openings. Between the ridges are nar- row intercostal grooves that are comparable to the canals of the pore- canal system of some other fishes (Gross, 1956, p. 135).. Fig. 93. Dorsal shield of a cyathaspid, showing measurements employed. A, dorsal view, and B, lateral view. ML, median length; OL, orbital length; OW, orbital width; PEL, postbranchial length; PL, pineal length; W, maximum width. The following measurements (fig. 93) and ratios
. The Cyathaspididae; a family of Silurian and Devonian jawless vertebrates. Cyathaspididae. DENISON: THE CYATHASPIDIDAE 317 over the orbits and branchial openings. Between the ridges are nar- row intercostal grooves that are comparable to the canals of the pore- canal system of some other fishes (Gross, 1956, p. 135).. Fig. 93. Dorsal shield of a cyathaspid, showing measurements employed. A, dorsal view, and B, lateral view. ML, median length; OL, orbital length; OW, orbital width; PEL, postbranchial length; PL, pineal length; W, maximum width. The following measurements (fig. 93) and ratios have been used for the dorsal shield: Median length (or length) Maximum width (or width) Orbital width (or width at orbital notches) Orbital length (or median length from anterior border to a line between the orbital notches) Pineal length (or median length from anterior border to the center of the pineal macula) Postbranchial length (or median length from posterior border to a line between the external branchial openings) maximum width , , , , , . , . Tr. , TT . Width ratio = -medi-an length (breadtiiJen^h index of Kiaer and Heintz, orbital width Orbital width ratio = m-edian length orbital length , . , ,,,. , TT . ,„„ .„. Orbital ratio = m^dianiength (rostral index of Kiaer and Heintz, 193o, p. 46) Pineal ratio = Postbranchial ratio pineal length median length postbranchial length median length. 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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