[Such, however, was not the case with Mr. Darwin.² When I subsequently ventured to put the similar question to the master, he at once most kindly favoured me with the following reply, which I give in his own words, in order to avoid anything like a mis-statement of his views:— After speaking of there being “some gradation in perfection with mammals in the mammery glands,” and the custom of the young in the Echidna (of the crab family), and the Ornithoptera (of the butterfly species) “to suck off the surface of its skin, to secrete milk, for there is no nipple,” Mr. Darwin added: ‘In the case of certain fish the ova are hatched in a marsupal sack on the surface of the stomach of the male, and the young when hatched feed on the mucus secreted from the skin lining the sack; and here as I believe, we see what might be the commencement of a simple mammery gland as in Echidna, &c. This is of course only an hypothesis. The exact steps in the evolutionary process could be discovered only by the observation of animals which became extinct during the earliest part of the secondary period.”³]