52 INTRODUCTION. 



portional size to these and Myrmecohius. Tlie 

 exact condition of the incisors and canines of the 

 Tht/lacotherium has not yet been displayed in the 

 fossil jaws which have been 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 Marsiqnata. 

 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. 



•\ Magazine of Natural History for September 1839, p. 

 450. 



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



