. The Bashford Dean memorial volume :. Fishes; Sharks; Fishes, Fossil. Text-figure 58. Section through the tropeic folds (x 25) of a 210 mm. embryo of Chlamydoselachus, showing the keel muscle {\.m.). The section was taken about 15 mm. in front of the pelvis. Drawn from a specimen collected in Japan by Dr. Bashford Dean, and now in the American Museum. under consideration. It is clearly derived as a simple inpocketing of the ventral muscula' ture of the body wall, in the region where the ventral bundles of the two sides of the body meet. Furthermore, it is segmented after the fashion of the me
. The Bashford Dean memorial volume :. Fishes; Sharks; Fishes, Fossil. Text-figure 58. Section through the tropeic folds (x 25) of a 210 mm. embryo of Chlamydoselachus, showing the keel muscle {\.m.). The section was taken about 15 mm. in front of the pelvis. Drawn from a specimen collected in Japan by Dr. Bashford Dean, and now in the American Museum. under consideration. It is clearly derived as a simple inpocketing of the ventral muscula' ture of the body wall, in the region where the ventral bundles of the two sides of the body meet. Furthermore, it is segmented after the fashion of the metameric muscles of the body wall—a feature that is entirely lacking in Carman's drawings and is not men' tioned in his text. Earlier stages would be required to show continuity of the muscula' ture in this region. Evidence regarding the manner of origin of the keel muscle was obtained by Braus (1898, Fig. 2, pi. XIII) in connection with his studies of the innervation. In this case the depth of the "keel" is remarkable. Braus appUes the term rectus to the thin muscle of the body wall in the region of the ventral mid'line—a muscle which is interrupted by. MohL iM. 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 Dean, Bashford, 1867-1928; Gudger, E. W. (Eugene Willis), 1866-1956. New York : [American Museum of Natural History],
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