. Biology of the vertebrates : a comparative study of man and his animal allies. Vertebrates; Vertebrates -- Anatomy; Anatomy, Comparative. Pelvic Fin Fig. 526. Embryo of the dogfish Scyllium, showing myotomes sending out muscle-buds along entire trunk region. (After Goodrich.) Between successive muscle buds cartilage formation, through the activity of mesenchymal cells, takes place, giving rise to more or less parallel rows of elongate radial cartilages (Fig. 527). At approximately the same time, a concentration, or crowding of structures, in the base of the fin occurs due to the failure of t
. Biology of the vertebrates : a comparative study of man and his animal allies. Vertebrates; Vertebrates -- Anatomy; Anatomy, Comparative. Pelvic Fin Fig. 526. Embryo of the dogfish Scyllium, showing myotomes sending out muscle-buds along entire trunk region. (After Goodrich.) Between successive muscle buds cartilage formation, through the activity of mesenchymal cells, takes place, giving rise to more or less parallel rows of elongate radial cartilages (Fig. 527). At approximately the same time, a concentration, or crowding of structures, in the base of the fin occurs due to the failure of this basal region to keep pace, in its growth, with the rest of. 0<3 ⢠Pelvic Girdlex 1 511^1 0 I ffl 0 â 5 Radials fl s Fig. 527. Diagrams showing limb girdles arising by the concentration, splitting off, and fusion of basal cartilages. (After Hyman and Thacher.) the fin and with the body proper. It is believed that in the course of evolu- tion a concrescence, or fusion, of the crowded basal portions of the primitive radials gave rise to the large basal cartilages. In development these three stages are telescoped together, instead of following one after the other, so that by the time the procartilaginous stage is reached there is a continuous basal mass from which extend out finger-like processes in which the radials will develop (Fig. 528). Up to this point the development of the median fins parallels rather closely that of the paired fins, as might be expected if all of these appendages are but localized enlargements of one continuous system. The basalia of the. 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 Walter, Herbert Eugene, b. 1867; Sayles, Leonard Perkins, 1902-. New York : Macmillan Co.
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