52 INTRODUCTION. 



portional size to these and Myrmecobius. The 

 exact condition of the incisors and canines of the 

 Thylacotherium has not yet heen displayed in the 

 fossil jaws which have heen discovered."* 



Besides the Stonesfield fossils alluded to, and 

 those of the Paris Plaster, Mr. Charleswortht re- 

 fers a certain fragment found in the London clay, 

 near Woodbridge, in Suffolk, to the Marsupiata. 

 This fragment consists of a portion of the right 

 ramus of a lower jaw containing one false molar 

 tooth. Mr. Charlesworth observes, " that the tooth 

 in its symmetrical form, united with the indication 

 of an anterior and posterior heel or talon, does not 

 agree with any species of Didelph with which I 

 have as yet been able to compare it ; but I think 

 no doubt can be entertained of the generic or family 

 affinities indicated by the character which it ex- 

 hibits." Mr. Owen, in a paper J on the same frag- 

 ment, regards the reference of this fragment to the 

 genus Didelphys as premature, though it bears so 

 close a resemblance to the corresponding part of the 

 Opossum, as, in his opinion, to warrant the expecta- 

 tion, that subsequent discoveries may prove the dif- 

 ferences which exist to be merely specific. 



* See Professor Owen's " Outlines of a Classification of 

 the Marsupialia," Proceedings of the Geological Society for 

 January 1839, pp. 8 and 9. 



f Magazine of Natural History for September 1839, p. 

 450. 



$ Annals of Natural History for November 1839, p. 192. 



