On the development and succession of the teeth in the Marsupialia : (abstract) / by William Henry Flower.

  • Flower, William Henry, 1831-1899.
Date:
1867
Catalogue details

Licence: Public Domain Mark

Credit: On the development and succession of the teeth in the Marsupialia : (abstract) / by William Henry Flower. 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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    [From the Proceedings of ti Royal Society, No. 93, 1867.] ON THE __ , V ■/9? DEVELOPMENT AND SUCCE^flON^f; */ niV ft ' OF THE P 4 ##' s4fe»* TEETH IN THE MARSUPIALIA.^wii^ by WILLIAM HENRY FLOWER, F.R.S., E.R.C.S., &c., CONSERVATOR OF THE MUSEUM OF THE ROYAL COLLEGE OF SURGEONS OF ENGLAND. (Abstract.) Although the dentition of adult individuals of all the animals which con- stitute the remarkable Order or, rather, Subclass Marsupialia, have been repeatedly subjected to examination, and described with exhaustive minute- ness of detail, it is a singular circumstance that most of those peculiarities in the succession of their teeth which distinguish them from other mammals appear hitherto to have escaped observation. To supply this blank is the object of the present communication. Fortunately the materials at my disposal, although not quite so complete as might be desired, are yet amply sufficient to illustrate the main aspects of the question, and to supply a result as interesting as it was unexpected. Descriptions are given in the paper, accompanied by drawings, of several stages of the dentition of members of each of the six natural families into which the order is divided. 1. Macropodidce.—The dentition of the Kangaroo (genus Macropus), from the completely edentulous foetus to adult age, is described in detail. Contrary to what has been specially stated with regard to this genus, there are no deciduous or milk-incisors, the teeth of this group which are first formed and calcified in both jaws being those which are retained throughout the life of the animal. The rudimentary canine and first premolar have also no deciduous predecessors. The second tooth of the molar series (a true molar in form) is vertically displaced by a premolar. The four true molars have, as has long been known, no deciduous predecessors. There is thus but one tooth on each side of each jaw in which the phenomenon of diphyo- dont succession occurs. The period at which this takes place varies in different species of the family. In some forms of Hypsiprymnus, the suc- cessional premolar is not cut until after the last true molar is in place and use,—this probably having relation to the extraordinary size of the tooth, and the time consequently required for its development. A special charac- teristic of this family is the tendency to lose the canine and one or both premolars at a comparatively early period of life. 2. Phalangistidce.—Several early stages of the dentition of Phalangista vulpina are described and figured. In a young specimen in which no teeth had cut the gum, the crowns of the permanent incisors, canine, and first two molars were found to be calcified, and the germ of the permanent pre- molar was already formed beneath the milk- or deciduous molar, which, as