Mr. Owen's Letter to the Editors, fyc. 341 



owing to the washing down of the diluvium ; still it can be seen 

 to advantage at various points of the locality described. The 

 principal exposure presents a section of about fifty feet in height, 



which in the ascending order will stand thus, — eight feet dark 



green sand ; twelve feet mottled sand and clay, both eocene, up- 

 per surface very irregular and covered by the usual thin stratum 

 of dark colored pebbles; one foot white compact sand and clay 

 containing casts of Pectens and other fossils, and passing into 

 the infusorial stratum, which is thirty feet. 



A more particular description will appear in a notice which I 

 am preparing, of some of the localities around Petersburg, which 

 may serve as a guide to geologists visiting this interesting portion 

 of the tertiary formation of Virginia. 



Petersburg, Va., Dec. 2lst, 1842. 



Art. X. — Letter from Richard Owen, Esq., F. /?. &., F. 

 Sfc. $*c, on Dr. Harlan's Notice of New Fossil Mamm 

 published in this Journal, Vol. xliii, p. 141. 



[TO THE EDITORS OF THE AMERICAN JOURNAL OF SCIENCE.] 



London, Dec. 10th, 1842.* 



Gentlemen — Permit me to state, in reference to some observa- 

 tions in an interesting notice of some new fossil mammalia, inserted 

 in your valuable Journal, (Vol. xliii, p. 141,) by my esteemed 

 friend, Dr. R. Harlan, that my genus Mylodon was not founded 

 on the Doctor's description of the Megalonyx laqueatus, in his 

 Medical and Physical Researches, (p. 319 — 332,) nor does it in- 

 clude that species, which is a true Megalonyx. 



Dr. Harlan appears to have been led into the error by an arti- 

 cle in the Penny Cyclopaedia, which he attributes to me. In 

 justice to the accomplished naturalists who contribute the zoolo- 

 gical articles in that work, I cannot permit myself to retain the 

 credit of writings which are not mine, but which any zoologist 

 might be proud to acknowledge. The names of the contribu- 

 tors have been published by the society, to whom we owe the 

 diffusion of the useful knowledge contained in the Penny Cyclo- 

 pedia. I have never contributed any article to that work. 





* Received January 27th, 1843. 





