Hardwicke's science-gossip : an illustrated medium of interchange and gossip for students and lovers of nature . Fig:. 64. Pedicellaria, x 60. Fig. 65. Section of Tooth. rodent; they have the same chisel-shaped form,but they have an addition in the shape of a keelwhich runs along the back. If a longitudinal sec-tion of one of these teeth be examined, it will beseen to bear a striking resemblance in its structureto the teeth of the higher animals. The keel is composed of rods of carbonate oflime, lying obliquely to the axis of the tooth. Thechisel-shaped edge consists firstly of a series oftria
Hardwicke's science-gossip : an illustrated medium of interchange and gossip for students and lovers of nature . Fig:. 64. Pedicellaria, x 60. Fig. 65. Section of Tooth. rodent; they have the same chisel-shaped form,but they have an addition in the shape of a keelwhich runs along the back. If a longitudinal sec-tion of one of these teeth be examined, it will beseen to bear a striking resemblance in its structureto the teeth of the higher animals. The keel is composed of rods of carbonate oflime, lying obliquely to the axis of the tooth. Thechisel-shaped edge consists firstly of a series oftriangular calcareous plates, called the primaryplates; these constitute a framework with whichthe other parts become connected. To these plates,at some distance from the base, are attached a. Fig-. 66. Longitudinal Section of Tooth. series of lappet-shaped lamina;, called by Mr. Salterthe secondary plates To these again are added athird set of appendages named the flabelliformprocesses; these last consist of reticulations ofcalcareous fibres, having a fan-shaped flabelliform processes are succeeded nearer theapex by an appearance closely resembling the tubuli of bone or dentine. This is caused by thedifferent portions of the tooth being more or lessclosely cemented together by minute particles ofcalcareous matter, which bear the name of the sol-dering particles. Thus a longitudinal section ofthe tooth presents somewhat the appearance ofbone with its lacunae, canaliculi, and laminae. Theedge of the chisel-shaped portion of this tooth iscoated with a layer of enamel. The tooth is shownin longitudinal section in Figs. G5 and 66. The plates and processes of the lantern par-take of the general network structure of the shell,and therefore call for no particular r
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Keywords: ., bookcentury1800, booksubjectnaturalhistory, booksubjectscience