LETTER 158. TO JOHN LUBBOCK [LORD AVEBURY]. Down, January 23rd [1863].

I have no criticism, except one sentence not perfectly smooth. I think your introductory remarks very striking, interesting, and novel. (158/1. "On the Development of Chloeon (Ephemera) dimidiatum, Part I. By John Lubbock. "Trans. Linn. Soc." Volume XXIV., pages 61-78, 1864 [Read January 15th, 1863].) They interested me the more, because the vaguest thoughts of the same kind had passed through my head; but I had no idea that they could be so well developed, nor did I know of exceptions. Sitaris and Meloe (158/2. Sitaris and Meloe, two genera of coleopterous insects, are referred to by Lubbock (op. cit., pages 63-64) as "perhaps...the most remarkable cases...among the Coleoptera" of curious and complicated metamorphoses.) seem very good. You have put the whole case of metamorphosis in a new light; I dare say what you remark about poverty of fresh-water is very true. (158/3. "We cannot but be struck by the poverty of the fresh-water fauna when compared with that of the ocean" (op. cit., page 64).) I think you might write a memoir on fresh-water productions. I suggest that the key-note is that land-productions are higher and have advantage in general over marine; and consequently land-productions have generally been modified into fresh-water productions, instead of marine productions being directly changed into fresh-water productions, as at first seems more probable, as the chance of immigration is always open from sea to rivers and ponds.

My talk with you did me a deal of good, and I enjoyed it much.