1 857.] NOVARA EXPEDITION. 93. 



I am really very much obliged for your letter, for, though I 

 intended to put only one sentence and that vaguely, I should 

 probably have put that much too strongly. 



Ever, my dear Hooker, yours most truly, 



C. DARWIN. 



P.S. This note, as you see, has not anything requiring an 

 answer. 



The distribution of fresh-water molluscs has been a horrid 

 incubus to. me, but I think I know my way now ; when first 

 hatched they are very active, and I have had thirty or forty 

 crawl on a dead duck's foot ; and they cannot be jerked off, 

 and will live fifteen and even twenty-four hours out of water. 



[The following letter refers to the expedition of the Austrian 

 frigate Novara ; Lyell had asked my father for suggestions.] 



C Darwin to C. Lyell. 



Down, Feb. iith[i85;]. 



MY DEAR LYELL, I was glad to see in the newspapers 

 about the Austrian Expedition. I have nothing to add geolo- 

 gically to my notes in the Manual.* I do not know whether 

 the Expedition is tied down to call at only fixed spots. But 

 if there be any choice or power in the scientific men to 

 influence the places this would be most desirable. It is my 

 most deliberate conviction that nothing would aid more, 

 Natural History, than careful collecting and investigating all 

 the productions of the most isolated islands, especially of the 

 southern hemisphere. Except Tristan d'Acunha and Ker- 

 guelen Land, they are very imperfectly known ; and even at 

 Kerguelen Land, how much there is to make out about the 

 lignite beds, and whether there are signs of old Glacial action. 

 Every sea-shell and insect and plant is of value from such 

 spots. Some one in the Expedition especially ought to have 



* The article " Geology " in the Admiralty ' Manual of Scientific 

 Enquiry.' 



