. The Bashford Dean memorial volume : archaic fishes. Fishes; Sharks; Fishes, Fossil. 286 Bashford Dean Memorial Volume others in the cloacal region, will be further considered in the article on the anatomy of the frilled shark. DERMAL DENTICLES The placoid scales or dermal denticles cover the entire body, including the fins and that part of the sclera which is exposed when the eyes are turned upward; also they line the mouth, gullet, and branchial arches. In sharks generally, the skin with its close^set denticles comprises what is called shagreen. The dermal denticles ot Chlamydoselachus have
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. The Bashford Dean memorial volume : archaic fishes. Fishes; Sharks; Fishes, Fossil. 286 Bashford Dean Memorial Volume others in the cloacal region, will be further considered in the article on the anatomy of the frilled shark. DERMAL DENTICLES The placoid scales or dermal denticles cover the entire body, including the fins and that part of the sclera which is exposed when the eyes are turned upward; also they line the mouth, gullet, and branchial arches. In sharks generally, the skin with its close^set denticles comprises what is called shagreen. The dermal denticles ot Chlamydoselachus have been studied by two investigators, Garman and Rose. The former (1885.7, pp. 6 and 7) says: Over the entire body the scales are small and irregular in size and shape. On the flank and belly they are polygonal plates, or depressed lumps . . surmountedbyone, two, or three sharp prominences, the median of which is stronger, in places becoming a keel. On the tail this keel is produced beyond the base as a spine. This spine is very sharp, has three longi- tudinal ridges, and is excavated slightly or flattened beneath. About the mouth and in particular around its angles the spines are larger, more conical, and more erect—more like teeth. [Carman's PI. VI, fig. 12 reproduced as our Text-figure 13]. Each of a few of these scales has a small cusp near its base. In the mouth, just behind the last row of teeth, there are spines which are more slender, and which have broader bases. . From each side of the lateral line elongate scales with chisel-shaped or truncate ends reach out to meet similar ones from the other side, thus forming a cover or protection for the canal. [Carman's PL VI, fig. 10—our Text-figure 18.] The scales have been studied by Rose (1895) in connection with his work on the teeth. These scales came from a 340-mm. (13.4'in.) embryo taken from the "uterus" of. Please note that these images are extracted from scanned page images that may have been digitally enh