72 APPENDIX. 



of it, executed by your instructions, would have illustrated 

 your description of that fossil instead of mine. 



A few words, now, with respect to your article entitled 

 * On the discovery of a portion of Opossum's jaw,' ( pp. 448 

 and 450, *Mag. Nat. Hist.,' Sept. 1839). You knew that I 

 had previously announced to Mr. Lyell, the existence of a 

 marsupial fossil in the London clay : Mr. Colchester and 

 Mr. S. Wood were also aware of that fact before you pub- 

 lished your * Discovery.' Moreover, your own conclusion, 

 that the jaw which you obtained from Mr. Colchester was 

 that of an opossum, is at variance with your description of 

 that fossil; for, if the tooth which you say (p. 450), " appears 

 to be the one immediately succeeding the true molars," had 

 been what you supposed it, then the fossil could not have 

 belonged to the genus Didelphis, for the reasons which I 

 have assigned in the * Annals of Natural History ' for No- 

 vember. 



I have reason to believe that you were aware of the general 

 result of my comparison of Mr. Colchester's London-clay fos- 

 sil molar tooth, submitted to me by Mr. Lyell, in June last, 

 before you published your own account of the opossum's 

 jaw from the same formation. It is no justification of your 

 silence with respect to my previous announcement of a fossil 

 marsupial in the London clay, that I was induced to alter my 

 opinion of it some time after the publication of your paper. 

 I remain. Sir, 



Your obedient Servant, 



RICHD. OWEN. 

 Editor Mag. Nat. Hist. 



