926 



DR. A. HOPEWELL-SMITH AND DR. H. W. MARETT TIMS ON 



39. Tooth-germs in the Wallahy Macropus Ullardieri. 

 By A. Hopewell-Smith, L.R.C.P., M.E.C.S., and 

 H. W. Makett Tims, M.A., M.D., F.L.S., F.Z.S., 



King's College, Cambridge. 



[Received and Eead May 23, 1911.] 



(Plate XLYIL* and Text-figm-es 181-189.) 



The dentition of the Max-supials ofters, in some respects, points 

 of greater interest than does that of other mammals. Thongh 

 much has been already written npon this subject, there are still 

 problems awaiting solution. 



The complete history of the tooth-genesis has been Avorked out 

 in few members of this class, due no doubt to the difficulty of 

 obtaining a sufficiently complete seiies of embryos of any one 

 species. Any contribution, therefore, however small, may become 

 of importance as forming a link in completing the chain of 

 evidence. 



The material upon which these observations are based consisted 

 of three embiyos of Macj'opus hillardieri, obtained from the Seven 

 Sisters Islands by Mr. Brooke Nicholls of Melbourne, to whom 

 we are greatly indebted for his kindness in sending them for 

 examiuation. These embiyos give the following measurements : — 



Serial sections were cut in a vertical transverse direction 

 though the skulls of Stages I and II and stained with borax 

 carmine. The jaws of Stage III, which gave measurements 

 approximately equal to those of Stage II and presumably therefore 

 of an embryo of about the same age, were dissected and clarified 

 in oil of cloves after the method recommended by Huxley, to 

 show the relative positions of the calcified teeth. 



The most detailed accounts of the development of the teeth in 

 Diprotodont Marsupials are those given by M, F. Woodward (12) 



* .For explanation of the Plate see p. 942. 



