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From:
Charles Robert Darwin
To:
George Robert Waterhouse
Date:
[31 July 1843]
Source of text:
DAR 185: 69
Summary:

Has no objection to uniting Monotremata and other marsupials but would object to doing so solely on ground that Monotremata consists of only two species. Members of a natural group need not share common character so long as they are linked with those which do. Believes that if every organism that ever lived were collected, a perfect series would be presented. What are reasons that unite Aptera and Diptera?

Contributor:
Darwin Correspondence Project
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From:
William Henry Smyth
To:
Sir John Herschel
Date:
[31 July 1843]
Source of text:
TxU:H/M-0493; Reel 1093
Summary:

Problems with computation of Gamma Virginis.

Contributor:
John Herschel Project