. On the anatomy of vertebrates. Vertebrates; Anatomy, Comparative; 1866. 598 ANATOMY OF VERTEBRATES. granules and granular cor]nxscles, more immediately surrounding the germ-cell; which, moving from the centre to the periphery of the yolk, there forms the ' cicatricula,' the exclusive seat of subsequent developement. In the cartilaginous Fishes the im- pregnating influence is received before the ovum quits the ovarium, or shortly after. In the ^'9 egg's passage through the oviduct the yolk is sur- rounded by fluid albumen, and finally by a case of the denser albuminous secretion of the nida-
. On the anatomy of vertebrates. Vertebrates; Anatomy, Comparative; 1866. 598 ANATOMY OF VERTEBRATES. granules and granular cor]nxscles, more immediately surrounding the germ-cell; which, moving from the centre to the periphery of the yolk, there forms the ' cicatricula,' the exclusive seat of subsequent developement. In the cartilaginous Fishes the im- pregnating influence is received before the ovum quits the ovarium, or shortly after. In the ^'9 egg's passage through the oviduct the yolk is sur- rounded by fluid albumen, and finally by a case of the denser albuminous secretion of the nida- mental gland. The form of the egg when thus invested is remarkable, and different in diflerent genera. In the Skate, fig. 419, A, it is an oblong quad- rangular flattened case, with the angles prodixced forward and backward, like those of a butcher's tray. In the Spotted Dog-fish, ib. B, the ova are also quadrangular, but longer, and the angles are extended into filamen- tary tendrils, which attach themselves to floating bodies, and thus keep the ovum near the surface, where the influence of solar heat and light is greatest. In Ahtidanus, vfith a similarly shaped cirri- gerous egg, the anterior and posterior surfaces are crossed by about twenty parallel transverse ridges.' In Cestracion the egg is pyriform, with a broad ridge, or plate, wound edge-wise round it in five spiral volutions. The eggs of Callorhpichus resemble a broad-leaved fucus, in the form of a long depressed ellipse, with a plicated and fringed margin.^ The ovum of the Myxinc (jluthwsa, fig. 419, C, is a long ellipse, terminated at each end by a tassel of slender tubular filaments, twenty-five to thirty in number, expanding at their free end (opposite d) into a funnel- shaped process.' ' XX. vol. T. p. 70, preps, nos. 3245, 3246. '^ XX. vol. V. p. 69, prcjis, nos. 3235, A. iind is. » cocviir. p. External form of ova of Oviparous CartCaginous Fisbeg. Please note that these images are extracted fro
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