. On the anatomy of vertebrates. Vertebrates; Anatomy, Comparative; 1866. &74 ANATOMY OF VERTEBRATES. 260. PorLioli of tlie jaw of Lopliiiis pisratnring, showing the lign- mciitons attaclimcnt of tlic tot'tli. v. of tliciv summits (^Sca?-?is, fig. 2,59); in Pimelodus, however, where the tcetli are thus attached, the crown is bent down in the upper teeth, and bent up in the lower ones, at right angles to the fang, so that they oppose each other by the normal surfaces. Certain teeth of recent and fossil cartilaginous fishes have their base divided into processes like fangs, but these serve f
. On the anatomy of vertebrates. Vertebrates; Anatomy, Comparative; 1866. &74 ANATOMY OF VERTEBRATES. 260. PorLioli of tlie jaw of Lopliiiis pisratnring, showing the lign- mciitons attaclimcnt of tlic tot'tli. v. of tliciv summits (^Sca?-?is, fig. 2,59); in Pimelodus, however, where the tcetli are thus attached, the crown is bent down in the upper teeth, and bent up in the lower ones, at right angles to the fang, so that they oppose each other by the normal surfaces. Certain teeth of recent and fossil cartilaginous fishes have their base divided into processes like fangs, but these serve for the attach- ment of ligaments, and are not set in bony sockets like the true fangs or roots of the teeth of Mam- mals. The base of anchylosed teeth is, at first, attached to the jawbone by liga- ment; and in the Cod-fish, AYolf-fish, and some other spe- cies, as calcification of tlie tootli })rogresses towards its base, the sul)jacent portion of the jawbone receives a stimulus, and developes a process corres- ponding in size and form with the base of the tooth : for some time a thin layer of ligamentous substance intervenes, but anchylosis usually takes pdace to a greater or less extent before the tooth is shed. Most of nhriis). \. the teeth of the Lophius re- tain the primitive connection; the ligaments, fig. 260, f?, of the large internal or posterior teetli of the upper and lower jaws, radiate on tlie corresponding sides of the bone, the base of the tooth resting on a conformable alveolar process. The ligaments do not permit tlic tooth to be bent outward beyond the vertical position, but yield to pressure in the contrary direction, by which the point of the tootli may be directed towards the back of the mouth, as at c; tlie instant, however, tliat the jiressnre is remitted, the tootli returns tlirongh the elasticity of the bent ligaments, as by the action of a spring, into its usual erect position, h ; tlio deglutition of the prey of this voracious Ksh is thus facilitated
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Keywords: ., bookauthorowenrichard18041892, bookcentury1800, bookdecade1860
