. On the anatomy of vertebrates. Vertebrates; Anatomy, Comparative; 1866. 390 ANATOMY OF TfCLli of Mcuoiiomc ; fc prcmaxiJlniy, I vomerine, X raaxlllaTy by the various sinuosities of the interblended folds of cement and processes of dentine, with the partial dilatations of the radiated pulp-cavity, produces the complicated structure which is described at p. 365, and figured in cut 244. Developement.—The teeth of Eeptiles are never completed at the first or pajiillary stage ; the pulp 265 sinks into a follicle, and becomes inclosed by a capsule; and in certain reptiles this become
. On the anatomy of vertebrates. Vertebrates; Anatomy, Comparative; 1866. 390 ANATOMY OF TfCLli of Mcuoiiomc ; fc prcmaxiJlniy, I vomerine, X raaxlllaTy by the various sinuosities of the interblended folds of cement and processes of dentine, with the partial dilatations of the radiated pulp-cavity, produces the complicated structure which is described at p. 365, and figured in cut 244. Developement.—The teeth of Eeptiles are never completed at the first or pajiillary stage ; the pulp 265 sinks into a follicle, and becomes inclosed by a capsule; and in certain reptiles this becomes more or less surrounded by bone ; but the ' eruptive' stage, in the sense in which this is usually understood, as signifying the ex- trication of the young tooth from a closed alveolus, is not exem- plified in recent Reptiles, and was rare in extinct ones.' The completion of a tooth, with the exception of the Dicy- nodont Reptiles, is soon fol- lowed by preparation for its removal and succession; the faculty of developing new tooth- germs seems to be unlimited in the present class, and the phe- nomena of dental decadence and replacement are manifested at every period of life ; the number of teeth is generally the same in each successive series, and the diflPerence of size presented by the teeth of different and distant series in the same individual is considerable. The new germ is always developed, in the first instance, at the side of the base of the old tooth, never in the cavity of the base; the crocodiles form no exception to this rule. The poison-fangs of serpents succeed each other from behind forwards; in almost every other instance the germ of the succes- sional tooth is developed at the inner side of the base of its predecessor. In the Frog the dental germ makes its appear- ance in the form of a papilla developed from the bottom and towards the outer side of a small fissure in the mucous membrane or gum that fills up the shallow groove at the inner side of the alve
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Keywords: ., bookauthorowenrichard18041892, bookcentury1800, bookdecade1860
