A manual of dental anatomy : human and comparative / by Charles S. Tomes.

  • Tomes, Charles S. (Charles Sissmore), Sir, 1846-1928.
Date:
1904
Catalogue details

Licence: In copyright

Credit: A manual of dental anatomy : human and comparative / by Charles S. Tomes. Source: Wellcome Collection.

Provider: This material has been provided by The University of Leeds Library. The original may be consulted at The University of Leeds Library.

    627/668 (page 615)
    The deutal formula is— i cheek teeth The first pair of upper incisors are sharply pointed, are directed nearly vertically downwards, and grow from per- sistent pulps. The second and third do not grow from pei-sistent pulps, and their worn crowns do not attain to the same level as those of the hrst pair. All three paii-s are antagonised by the single pair of large procumbent low incisors, of which the sharp points meet the fii-st pair of upper incisors, while the obliquely-worn sm-face behind the cutting edges impinges against the second and third upper incisors. The arrangement of the incisors aud the sharpness of their cutting edges are calculated to effect the same objects as those attained by the incisors of a rodent; a still closer resemblance would be brought about by the dwindling (which occurs in other genera) and final disappearance of the second aud third upper incisors, and a compensating extra development of the first paiv. The canines are not large, yet they are not so small as to be termed rudimentary ; in the lower jaw they are absent. Only one premolar exists in the adult, aud this is a very pecidiar tooth; its crown is vei-y long from back to front (at least twice as long as any of the molars, and in some species as long as three of the molars), aud consists of a finely furrowed blade with a sharp edge; the blades of the upper and lower teeth slide over one another. Behind this there are four (?) true molars, with square quadricuspid crowns, which become much worn down by use. The ]a.st and only(?) premolar, the tooth to which attention ha.s alrcfidy been drawn on account of its size and other peculiarities, by virtue of its great size displaces not only the usually deciduous molar, to which it is the legitimate Hucces.sor, but also turns out the premolar in front of it (^). (') The old nomenclature ha« been here retiiiiied. If Lydekkers view be accepted these teeth would he two premolars and only three trueinohirs.