. The Bashford Dean memorial volume :. Fishes; Sharks; Fishes, Fossil. The Anatomy of Chlamydoselachus 395. Text-figure 69. Endoskeleton and musculature of male pelvic fins of Heptanchus maculatus. A—Skeleton of male left pelvic fin in dorsal view. and , connecting segments; ha., basal piece; , basipter- ygium; he., beta cartilage: pi., pelvic girdle; ra., radial cartilages. After Davidson, 1918, Fig. 8. B—Musculature of male right pelvic fin in dorsal view. ad., adductor muscle; cp., compressor muscle; d!., dilator muscle; , flexor externus; , flexor internus; p!., pelvic
. The Bashford Dean memorial volume :. Fishes; Sharks; Fishes, Fossil. The Anatomy of Chlamydoselachus 395. Text-figure 69. Endoskeleton and musculature of male pelvic fins of Heptanchus maculatus. A—Skeleton of male left pelvic fin in dorsal view. and , connecting segments; ha., basal piece; , basipter- ygium; he., beta cartilage: pi., pelvic girdle; ra., radial cartilages. After Davidson, 1918, Fig. 8. B—Musculature of male right pelvic fin in dorsal view. ad., adductor muscle; cp., compressor muscle; d!., dilator muscle; , flexor externus; , flexor internus; p!., pelvic girdle; ra., radial muscles; , muscle of sac or pocket. After Davidson, 1918, Fig. 9. detail by Goodey (, pp. 564-565) whose Figs. 20 and 21, pi. XLVI, are reproduced as my Figures 22 and 23, plate V, alongside Fig' ure 21 which shows the endoskeleton. The radial muscles {Ra., Figure 23, plate V) ex' hibit a division into bundles paralleling the radial cartilages. Concerning the ventral radial muscles Goodey says: ''On the ventral side there are the radial muscles Ra., which originate on the pelvic girdle close to the median line and extend outward to the horny fibers. Toward the anterior end the separate bundles have fused together, thus corresponding with the fusion of the radials ; The muscles of the clasper have been described in Heptanchus by Davidson (1918, pp. 165-167 and Fig. 9). Davidson's figure of the musculature is here reproduced as Text'figure 69b alongside his figure of the endoskeleton (Text-figure 69a). In both Chlamydoselachus (Figures 22 and 23, plate V) and Heptanchus (Text-figure 69b), the musculature of the myxopterygium is simple as compared with that of most elasmobranchs. Few differences are found when Chlamydoselachus and Heptanchus are compared with each other. As pointed out by Daniel (1934, p. 110), the principal difference is in the ad' ductors. In Heptanchus the adductor (ad. in Text-figure 69b) is a long muscle; in Chlamy
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