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Show 1893.] MR. M. F. WOODWARD ON MAMMALIAN DENTITION. 471 viz. m. 1. One of the most important factors in the modifications which we meet with in the Mammalian dentition is tbe shortening of the jaws, often accompanied by an enlargement of some of the teeth, thus causing a reduction and finally a suppression of some of the series. These missing teeth can be sometimes discovered through the study of Palaeontology, sometimes through the study of Abnormalities, but the surest method when possible is by the study of their development. The great variability of the anterior premolar of the living Placentalia and the insignificance of our knowledge concerning it, as to which dentition it is to be referred, alone show how futile are our attempts to homologize the dentitions of the leading orders of living Mammalia. And, reflecting upon the facts which I have herein recorded, I believe that our greatest desideratum at present is the further study of the development of the teeth of these animals, especially in its bearing upon the probable discovery and determination of vestigial teeth. My thanks are due to Prof. Howes for much valuable advice, and to Mr. Fletcher of Sydney, Dr. Symington, and Mr. Oldfield Thomas for gifts of much valuable material. IV.-LIST OF REFERENCES. 1. BAUME.-Versuch einer Entwicklungsg. d. Gebisses. Leipzig, 1882. 2. COPE.-"The Mechanical Cause of the Development of the hard parts of the Mammalia." Jour. Morph. vol. iii. 1889. 3. FLOWER, Sir W . H.-" On the Development and Succession of the Teeth in the Marsupialia." Phil. Trans, vol. 157. p. 631 (1867). 4. KUKENTHAL, W . - " Einige Bermerkungen lib. d. Saugetier- Bezahnung." Anat. Anz. 1891, p. 364. 5. KUKENTHAL, W . - " Das Gebiss v. Bidelphys." Anat. Anz. 1891, p. 658. These two papers are translated in the Ann. Mag. Nat. Hist. ser. 6, ix. pp. 279, 285 (1892). 6. LECHE.-" Studien fiber d. Entwick. d. Zahnsystems b. d. Saugethieren." M. J. xix. 1893, p. 502. 7. OWEN.-Art. " Teeth " in Todd's Cyclop. OWEN.-Mesozoic Mammals. Pal. Soc. 8. POUCHET et C H A B R T . - " Cont. a l'Odontologie d. Mammif." J. Anat. et Physiol. 1884. 9. ROSE.-" Ueber d. Zahnentwicklung d. Beuteltiere." Anat. Anz. 1892, p. 693. 10. THOMAS, 0.-" On Dr. Kiikenthal's discoveries in Mammalian Dentition." Ann. Mag. Nat. Hist. ser. 6, ix. p. 308 (1892). 11. THOMAS, 0.-"On the Homologies and Succession of the Teeth in the Basyuridce, with an attempt to trace the history of the evolution of the Mammalian Teeth in general." Phil Trans, vol. 178. pp. 443-462 (1887). 12. THOMAS, 0.-Catalogue of Marsupials Brit. Mus. 1888. 32* |