1860.] LYELL'S CRITICISMS. 



133 



rare or common in the best-known countries. I have got a 

 set of notes somewhere on the inhabitants of fresh water ; 

 and it is singular how many of these are ancient, or interme- 

 diate forms ; which I think is explained by the competition 

 having been less severe, and the rate of change of organic 

 forms having been slower in small confined areas, such as all 

 the fresh waters make compared with sea or land. 



I see that you do allude in the last page, as a difficulty, to 

 Marsupials not having become Placentals in Australia ; but 

 this I think you have no right at all to expect ; for we ought 

 to look at Marsupials and Placentals as having descended 

 from some intermediate and lower form. The argument of 

 Rodents not having become highly developed in Australia 

 (supposing that they have long existed there) is much stronger. 

 I grieve to see you hint at jhe creation " of distinct succes- 

 sive types, as well as of a certain number of distinct aborigi- 

 nal types." Remember, if you admit this, you give up the 

 embryological argument (the weightiest of all to me), and the 

 morphological or homological argument. You cut my throat, 

 and your own throat; and I believe will live to be sorry for 

 it. So much for species. 



The striking extract which E. copied was your own writ- 

 ing ! ! in a note to me, many long years ago which ?he 

 copied and sent to Mme. Sismondi ; and lately my aunt, in 

 sorting her letters, found E.'s and returned them to her. 

 .... I have been of late shamefully idle, /. e. observing * 

 instead of writing, and how much better fun observing is than 

 writing. 



Yours affectionately, 



C. DARWIN. 

 C. Darwin to C. LyelL 



15 Marine Parade, Eastbourne, 



Sunday [September 23rd, 1860]. 



MY DEAR LYELL, I got your letter of the i8th just be- 

 fore starting here. You speak of saving me trouble in an' 



* Dyosera. 



