On the development and homologies of the molar teeth of the wart-hogs (Phacochoerus) : with illustrations of a system of notation for the teeth in the class Mammalia / by Professor Owen.

  • Owen, Richard, Sir, 1804-1892.
Date:
1850
Catalogue details

Licence: Public Domain Mark

Credit: On the development and homologies of the molar teeth of the wart-hogs (Phacochoerus) : with illustrations of a system of notation for the teeth in the class Mammalia / by Professor Owen. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    phical Transactions for 1801, Home states that “fig. 3 represents the jaw in a still more advanced stage of its growth, with the tooth which was only forming in the second figure now come to its full size, and in its proper place in the row of teeth: there is also a new cell formed for a succeding tooth*.” The original specimen from which the figure is taken is preserved in the Hunterian Collection, and it shows that the supposed formative cell is one of a series of the medullary cells of the cancellous structure of this part of the jaw ; it is itself subdivided into smaller cells, and is not a simple cavity like the true cell of a forming tooth. It is also represented of twice its natural size in the figure cited, not having been reduced in proportion to the other parts of the jaw. The latest author on the subject of the dentition of the Phacochcerl, has ascribed to that part of their structure a character which would have added a still more re- markable anomaly to it, viz. that the last true molar represents both that tooth and the penultimate one in the Wild Boar and other herbivorous mammals-f. To this conclusion M. de Blainville was necessarily led by his determination of the antecedent teeth. Thus in a Phacochcerus with the dentition answering to that represented in figs. 4 and 5 of the present memoir, he regards the teeth marked p 3, p 4 and m 1 as belonging to the deciduous series, ‘ dents de lait;|:,’ and the rest as be- longing to the second dentition; p 2 being described as a small, speedily lost, false molar, m 2 as the first or antepenultimate true molar, and m 3 as the penultimate and last true molars, “already blended together, although not yet protruded from their formative alveolus With regard to the five teeth in the lower jaw, the first, p 3, is described as the first tooth of the second dentition; the two following, p 4 and m 1, as milk teeth; the fourth, m 2, as the antepenultimate molar of the second dentition, and the last, wi 3, as the penultimate and last molar coalesced. The dentition ascribed to the adult Phaco- choerus is that phase which is illustrated in figs. 9 and 10, Plate XXXIV. of the pre- 4 4 sent memoir, of which the numerical formula is 3^ =14. M. de Blainville, struck by the resemblance in the degree of attrition which the molar, m2, presents to the antepenultimate molar, ml, in the adult common Hog, deems them homologous, and deduces from that resemblance another argument for the homology of the last great molar of the Phacochere with the penultimate and last molars combined of the Hog 1|. * Philosophical Transactions, 1801, p. 331. t Osteographie des Ongulogrades, Hippopotamus and Sus, 4to, 1847. + Ibid. p. 148. § Ibid. p. 148. II “ Mais quelle est la signification de cette dent par rapport a ce qui existe chez la sanglier ? C’est la une question qui, malgre son interet, n’a pas merae encore ete soulevee. “ J’ai cru un moment qu’on pourrait la considerer comme representant les trois arriere-molaires qui se seraient soudees de maniere a n’en former qu’une, les trois molaires qui la precedent etant alors celies de remplacement. Cette fa9on de voir etait surtout appuyee sur la composition de cette dent a la mandibule ou I’on pent voir dans les cannelures laterales des separations plus marquees, paraissant indiquer I’antepenultieme, la penultieme et la derniere avec sou talon. “ Mais en reflechissant sur le caractere serial des especes de ce genre, il m'a semble que cette opinion devait MDCCCL. 3 R
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