Alfred Russel Wallace 



commensurate with the difference in size between the muscles 

 that raise the wings and the muscles that depress them. It 

 seems to me quite out of the question that the principles of 

 flight are fundamentally different in a bat and a bird, which 

 they must be if the Duke of Argyll's interpretation is correct. 

 I write, however, not so much to reply to your argument as 

 to correct a misapprehension which my expressions seem to 

 have given you. The objections are not made by Tyndall or 

 Huxley ; but they are objections made by me, which I stated 

 to them, and in which they agreed — Tyndall expressing the 

 opinion that I ought to make them public. I name this 

 because you may otherwise some day startle Tyndall or 

 Huxley by speaking to them of their objections, and giving 

 me as the authority for so affiliating them. — Very truly 



y^^^^j Herbert Spencer. 



Sir C. Lyell to A. B. Wallace 



73 Harley Street, London, W. November, 1867. 

 Dear Wallace, — You probably remember an article by 

 Agassiz in an American periodical, the Christian 01)server, 

 on the diversity of human races, etc., to prove that each 

 distinct race was originally created for each zoological and 

 botanical province. But while he makes out a good case for 

 the circumscription of the principal races to distinct pro- 

 vinces, he evades in a singular manner the community of the 

 Red Indian race to North and South America. He takes 

 pains to show that the same American race pervades North 

 and South America, or at least all America south of the 

 Arctic region. This was Dr. Morton's opinion, and is, I 

 suppose, not to be gainsaid. In other words, while the 

 Papuan, Indo-Malayan, Negro and other races are strictly 

 limited each of them to a particular region of mammalia, 

 the Red Indian type is common to Sclater's Neo-arctic and 

 Neo-tropical regions. Have you ever considered the explana- 



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