I send scrap of proofs from last edition of the "Origin," with the calculation corrected.

What grand work you did at Naples! I can clearly see that you will some day become our first star in Natural History.
(249/1.

Here follows the extract from the "Origin," sixth edition, page 51: "The elephant is reckoned the slowest breeder of all known animals, and I have taken some pains to estimate its probable minimum rate of natural increase.

It will be safest to assume that it begins breeding when thirty years old, and goes on breeding till ninety years old, bringing forth six young in the interval, and surviving till one hundred years old; if this be so, after a period of from 740 to 750 years, there would be nearly nineteen million elephants alive, descended from the first pair." In the fifth edition, page 75, the passage runs: "If this be so, at the end of the fifth century, there would be alive fifteen million elephants, descended from the first pair" (see "Athenaeum," June 5, July 3, 17, 24, 1869).) LETTER 250.

TO C.LYELL.Down, May 10th [1872].
I received yesterday morning your present of that work to which I, for one, as well as so many others, owe a debt of gratitude never to be forgotten.