. On the anatomy of vertebrates. Vertebrates; Anatomy, Comparative; 1866. ANATOMY OF VBRTEBKATES. 33 fluent at tlieir apices, which are perforated, and the notochord, reduced to a beaded form, is continued through them: the exterior of the bony cones is occupied Ijy a clear cartilage. In the Porbeagle Shark {Lamna cornubica) further ossification of the conical plate has reduced the central communication to a minute foramen. Os- seous plates have also been developed in the exterior clear cartilage: these plates are triangular, parallel with the axis of the vertebra, their apices converging towa
. On the anatomy of vertebrates. Vertebrates; Anatomy, Comparative; 1866. ANATOMY OF VBRTEBKATES. 33 fluent at tlieir apices, which are perforated, and the notochord, reduced to a beaded form, is continued through them: the exterior of the bony cones is occupied Ijy a clear cartilage. In the Porbeagle Shark {Lamna cornubica) further ossification of the conical plate has reduced the central communication to a minute foramen. Os- seous plates have also been developed in the exterior clear cartilage: these plates are triangular, parallel with the axis of the vertebra, their apices converging towards the centre: the interspaces are filled by v«,i™i t,,„,.^c,.. .cct.™ oj cartilage. In the great Basking Shark cuufumof,sw«<7,»™<,a:.ma CSelache maxima) fig. 26, the longitudinal bony lamina; are more numerous and shorter than in Lamna, are peripheral in position, and extend about one-third of the way towards the centre of the interspace between the terminal cones, the rest being occupied by a series of concentric cylinders of bone, interrupted by four conical converging cavities, filled by cartilage; of these, two, n, n, are closed by the bases of the neurapophyses, and two, jh Jh hy those of the parapophyses. There is a transition from the cylin- drical to the longitudinally lamellar structure, the exterior and largest of the cylinders sending out processes which join the in- ternal margins of the conver<2;ino; lamclla3. In the Monk-fish {Squatliui) the osseous jDart of the centrum between the termi- nal cones is entirely in the form of concentric layers, few in numl^er, and decreasing in breadth as they approach the centre. In the Cestracion there are no concentric cylinders, but only longitudinal lamellffi, radiating from the centre to the circumference, and giving off short lateral plates as they diverge. In the Topes (Galeus), the Blue Sharks (Carcharias), and in most sharks which possess the nictitating eyelid, may be seen the most advanced stage of
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Keywords: ., bookauthorowenrichard18041892, bookcentury1800, bookdecade1860
