"On certain Zoological Arguments commonly adduced in favour of the hypothesis of the Progressive Development of Animal Life," Discourse, Friday, April 20, 1855: "Proceedings R.I." (1855).

Published also in "Huxley's Scientific Memoirs." The lecturer dwelt chiefly on the argument of Agassiz, which he summarises as follows: "Homocercal fishes have in their embryonic state heterocercal tails; therefore heterocercality is, so far, a mark of an embryonic state as compared with homocercality, and the earlier heterocercal fish are embryonic as compared with the later homocercal." He shows that facts do not support this view, and concludes generally "that there is no real parallel between the successive forms assumed in the development of the life of the individual at present and those which have appeared at different epochs in the past.") I heard some time ago that before long I might congratulate you on becoming a married man.
(40/2.

Mr.Huxley was married July 21st, 1855.) From my own experience of some fifteen years, I am very sure that there is nothing in this wide world which more deserves congratulation, and most sincerely and heartily do I congratulate you, and wish you many years of as much happiness as this world can afford.
LETTER 41.

TO J.D.

HOOKER.
(41/1.