1893.] Mil. >r. F. AVOODWAltD OS MAMMALIAN DEXTITIOX. 471 



viz. m. 1. One ot" the most important factors in tlie modifica- 

 tions which we meet with in tlie Mammalian dentition is tlie 

 shortening of the jaws, often accompanied by an enlargement of 

 some of the teeth, thus causing a reduction and finally a suppres- 

 sion 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 farther study of the development of the teeth of 

 these animals, especiall}' 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 Eefekexces. 



1. Baume. — ^Yersuch einer Entwdcklungsg. d. Gebisses. Leipzig, 



18S2. 



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. KiJKEXTHAL, "W. — "Einige Bermerkungen lib. d. Siiugetier- 



Bezahnung." Anat. Anz. 1891, p. 364. 



5. KtJKENTHAL, W. — " Das Gebiss v. Didelj>hi/s." Anat. Anz. 



1891, p. 658. 

 These two papers are translated in the Ann. Mag. Xat. Hist, 

 ser. 6, ix. pp. 279, 285 (1892). 



6. Leche. — " Studien iibcr d. Entwick. d. Zahnsystems b. d. 



Saugethieren." M. J. xix. 1893, p. 502. 



7. Owen. — Art. " Teeth " in Todd's Cyclop. 

 Oavex. — Mesozoic Mammals. Pal. Soc. 



8. PoucHET et CiiAiiHY. — " Cout. a rOdonfologie d. Mannnif." 



J. Anat. et Physiol. 1884. 



9. Rose " Ueber d, Zahnentwicklung d. Beuteltiere." Anat. 



Anz. 1892, p. 693. 



10. TiroMAs, O. — " On Dr. Kiikenthal's discoveries in JNTammalian 



Dentition." Ann. Mag. Nat. Hist. ser. 6, ix. p. 308 (1«92). 



11. Thom.vs, O. — "On the Homologies and Succession of the 



Teeth in the Dasifi'ri(/ii', with an attempt to trace the 

 history of flie evolution of the Mammalian Teeth iu 

 general." Phil Trans, vol. 17s. pp. 443-462 (1887). 



12. Thomas, O.— Catalogue of Marsupials Brit. Mus. 1888, 



32* 



